阅读说明：本技术 一种空穴注入材料及有机电致发光器件 (Hole injection material and organic electroluminescent device ) 是由 张双 俞云海 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及有机电致发光器件,此空穴注入材料是富瓦烯类化合物,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基团,能够赋予分子较强的还原电位及较好的热稳定性,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 and an organic electroluminescent device, wherein the hole injection material is a fulvalene compound and contains cyano, fluoro, trifluoromethyl and the like. The technical scheme of the invention has good cross super-conjugation characteristic, combines strong electroabsorption groups such as cyano-group and fluoro-group, and can endow molecules with stronger reduction potential and better thermal stability, 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:

r-R

formula I

Wherein r isR is selected from a group containing a cyano group, a fluoro group or a trifluoromethyl group.

2. The hole injection material according to claim 1, wherein: and R is selected from cyano, fluoro, trifluoromethyl or substituted alkyl, alkoxy, aryl, heteroaryl and aryloxy thereof.

3. The hole injection material according to claim 1, wherein: a compound having the structure shown in formula I:

wherein R is₁-R₁₆Each independently selected from hydrogen, cyano, fluoro, trifluoromethyl, or cyano, fluoro, trifluoromethyl-substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁-R₁₆At least one of which contains a cyano group or a fluoro group.

4. The hole injection material according to claim 3, wherein: the compound with the structure shown in the formula I is:

5. the hole injection material according to claim 1, wherein: a compound having the structure shown in formula I:

wherein R is₁₇-R₃₀Each independently selected from hydrogen, cyano, fluoro, trifluoromethyl, or cyano, fluoro, trifluoromethyl-substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁₇-R₃₀At least one of which contains a cyano group or a fluoro group.

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

7. the hole injection material according to claim 1, wherein: a compound having the structure shown in formula I:

wherein R is₃₁-R₄₂Each independently selected from hydrogen, cyano, fluoro, trifluoromethyl, or cyano, fluoro, trifluoromethyl-substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₃₁-R₄₂At least one ofContaining cyano or fluoro groups.

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

9. an organic electroluminescent device, characterized in that: the organic electroluminescent device doped with the hole injection material according to any one of claims 1 to 8.

10. The organic electroluminescent device according to claim 9, wherein: the hole transport layer of the organic electroluminescent device is doped with the hole injection material according to any one of claims 1 to 8.

Technical Field

The invention relates to the field of organic electroluminescent devices, in particular to a hole injection material and an organic electroluminescent device with the hole injection material.

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. Therefore, the present invention provides a novel hole injection material and an organic electroluminescent device having the same.

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 and an organic electroluminescent device having the same, wherein the material has good cross-hyperconjugate characteristics, and can impart a strong reduction potential and good thermal stability to a molecule by combining with a strong electron-withdrawing group such as a cyano group, a fluoro group, a trifluoromethyl group, etc., thereby assisting a hole transport layer to efficiently inject holes.

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:

r-R

formula I

Wherein r isR is selected from a group containing a cyano group, a fluoro group or a trifluoromethyl group.

Preferably: and R is selected from cyano, fluoro, trifluoromethyl or substituted alkyl, alkoxy, aryl, heteroaryl and aryloxy thereof.

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

wherein R is₁-R₁₆Each independently selected from hydrogen, cyano, fluoro, or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁-R₁₆At least one of which contains a cyano group or a fluoro group.

Preferably: the compound with the structure shown in the formula I is:

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

wherein R is₁₇-R₃₀Each independently selected from hydrogen, cyano, fluoroOr cyano, fluoro, trifluoromethyl-substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁₇-R₃₀At least one of which contains a cyano group or a fluoro group.

Preferably: the compound with the structure shown in the formula I is:

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

wherein R is₃₁-R₄₂Each independently selected from hydrogen, cyano, fluoro, or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₃₁-R₄₂At least one of which contains a cyano group or a fluoro group.

Preferably: the compound with the structure shown in the formula I is:

according to another aspect of the present invention, there is also provided an organic electroluminescent device doped with the above hole injection material.

Preferably: the hole transport layer of the organic electroluminescent device is doped with the hole injection material.

The hole injection material and the organic electroluminescent device with the hole injection material have good cross super-conjugation characteristics, and can endow molecules with better thermal stability and stronger reduction potential by combining strong electron-absorbing groups such as cyano-group, fluoro-group, trifluoromethyl and the like, so that a hole transport layer is assisted 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 and an organic electroluminescent device having the same, having a compound of the structure represented by formula I:

a compound:

r-R

formula I

Wherein r isR is selected from a group containing a cyano group, a fluoro group or a trifluoromethyl group.

Wherein R is selected from cyano, fluoro, trifluoromethyl, or cyano, fluoro, trifluoromethyl 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 and good thermal stability by combining with strong electron-absorbing 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:

wherein R is₁-R₁₆Can be the same or different from each other and are each independently selected from hydrogen, cyano, fluoro, or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁-R₁₆At least one of which contains a cyano group or a fluoro group.

Preferred compounds of the structure shown in formula I are:

wherein R is₁₇-R₃₀Can be the same or different from each other and are each independently selected from hydrogen, cyano, fluoro, or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₁₇-R₃₀At least one of which contains a cyano group or a fluoro group.

Preferred compounds of the structure shown in formula I are:

wherein R is₃₁-R₄₂Can be the same or different from each other and are each independently selected from hydrogen, cyano, fluoro, or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy, and R₃₁-R₄₂At least one of which contains a cyano group or a fluoro group.

In the embodiments of the present invention, preferred R₁-R₄₂At least 1 of which contains a cyano group or a fluoro group, the others each independently being selected from hydrogen; or, cyano or cyano-substituted alkyl, alkoxy, aryl, heteroaryl, or aryloxy; or, fluoro or fluoro-substituted alkyl, alkoxy, aryl, heteroaryl, or aryloxy; alternatively, trifluoromethyl or trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl or aryloxy. Strong electron-withdrawing groups such as cyano groups and fluoro groups can impart a strong reduction potential to molecules, thereby assisting the hole transport layer in efficiently injecting holes.

And preferably the compound of formula I is:

the following specific examples describe the invention:

example 1

The preparation equation is as follows:

the method comprises the following steps:

adding TiCl to the reaction flask₃(65mg, 10% mmol), a-1(1.36g, 4.19mmol), Zn powder (1.37g,21.04mmol) and 18mL MeCN, Then (TMS) Cl (trimethylchlorosilane) (2.29g,21.04mmol) was added dropwise via syringe, heated at reflux for 1 hour under nitrogen, cooled, MeCN 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 eluent to give compound a-2.

The final product was determined to be MS: 615;

13C-NMR：(4C,119.6),(4C,120.1),(2C,126.3),(4C,136.5),(4C,137.4),(4C,144.5),(4C,145.1)。

example 2

The preparation equation is as follows:

the method comprises the following steps:

to the reaction flask were added b-1(92.7mg,0.126mmol), 3.7mL dry K₂CO₃(134.0mg,0.970mmol),n-Bu₄NHSO₄(82.0mg,0.240mmol) and Pd (OAc)₂(5.4mg,0.025mmol) was stirred at 122 ℃ for 51 h. Cooling, removing toluene, adding dichloromethane, washing with water, drying, passing the crude product through a column, using hexane/ethyl acetate (10:1) as eluent, and finally purifying to obtain compound b-2.

The final product was determined to be MS: 577;

13C-NMR：(2C,112.5),(4C,114.3),(2C,116.1),(2C,126.6),(2C,128.9),(4C,137.7),(2C,133.9),(2C,144.6),(4C,146.3),(2C,148.5)。

example 3

The preparation equation is as follows:

the method comprises the following steps:

to the reaction flask were added c-1(94.5mg,0.126mmol), 3.7mL dry K₂CO₃(134.0mg,0.970mmol),n-Bu₄NHSO₄(82.0mg,0.240mmol) and Pd (OAc)₂(5.4mg,0.025mmol) was stirred at 122 ℃ for 51 h. Cooling, removing toluene, adding dichloromethane, washing with water, drying, passing the crude product through a column, using hexane/ethyl acetate (10:1) as eluent, and finally purifying to obtain compound c-2.

The final product was determined to be MS: 591 of;

13C-NMR:(2C,96.7),(2C,112.5),(2C,113.4),(2C,116.1),(2C,116.5),(2C,126.6),(2C,128.9),(2C,130.8),(2C,133.9),(2C,136.8),(2C,144.6),(2C,148.5),(2C,154.2),(2C,155.0)。

example 4

The preparation equation is as follows:

the method comprises the following steps:

to the reaction flask were added d-1(107.8mg,0.126mmol), 7.4mL dry K₂CO₃(268.0mg,1.94mmol),n-Bu₄NHSO₄(164.0mg,0.48mmol) and Pd (OAc)₂(10.8mg,0.050mmol) was stirred at 130 ℃ for 100 h. Cooling, removing toluene, adding dichloromethane, washing with water, drying, passing the crude product through a column, using hexane/ethyl acetate (10:1) as eluent, and finally purifying to obtain compound d-2.

The final product was determined to be MS: 540;

13C-NMR:(4C,106.6),(4C,123.3),(4C,127.0),(2C,131),(4C,133.9),(4C,148.5),(4C,150.5)。

example 5

The preparation equation is as follows:

the method comprises the following steps:

adding TiCl to the reaction flask₃(65mg, 10% mmol), e-1(1.33g, 4.19mmol), Zn powder (1.37g,21.04mmol) and 18mL MeCN, Then (TMS) Cl (2.29g,21.04mmol) was added dropwise via syringe, heated under reflux for 1 hour under nitrogen, cooled, MeCN removed, dichloromethane added, water washed, dried, the crude product was passed through a column, hexane/ethyl acetate (10:1) was used as eluent, and the final purification afforded Compound e-2.

The final product was determined to be MS: 600, preparing a mixture;

13C-NMR：(4C,119.6),(8C,124.1),(2C,126.3),(4C,127.0),(4C,130.7),(4C,134.6),(4C,137.1)。

example 6

The preparation equation is as follows:

the method comprises the following steps:

to the reaction flask were added f-1(53.68mg,0.126mmol), 7.4mL dry K₂CO₃(268.0mg,1.94mmol),n-Bu₄NHSO₄(164mg,0.48mmol) and Pd (OAc)₂(10.8mg,0.050mmol) was stirred at 122 ℃ for 51 h. Cooling, removing toluene, adding dichloromethane, washing with water, drying, passing the crude product through a column, using hexane/ethyl acetate (10:1) as eluent, and finally purifying to obtain compound f-2.

The final product was determined to be MS: 426, respectively;

13C-NMR：(1C,110.3),(1C,116.5),(2C,121.5),(3C,122.4),(1C,122.9),((1C,123.1),1C,124.7),(6C,126.3),(2C,126.6),(1C,126.7),(3C,128.3),(1C,129.8),(2C,130.1),(1C,131.8),(2C,131.9),(1C,135.9),(1C,148.1),(2C,150.2)。

example 7

The preparation equation is as follows:

the method comprises the following steps:

adding g-1(52.80mg,0.126mmol) and sodium chloride into a reaction bottle,7.4mL of dried K₂CO₃(268.0mg,1.94mmol),n-Bu₄NHSO₄(164mg,0.48mmol) and Pd (OAc)₂(10.8mg,0.050mmol) was stirred at 122 ℃ for 51 h. Cooling, toluene removal, addition of dichloromethane, water washing, drying, column chromatography of the crude product, using hexane/ethyl acetate (10:1) as eluent, final purification gives compound g-2.

The final product was determined to be MS: 419;

13C-NMR：(1C,118.2),(1C,120.2),(4C,122.4),(1C,122.6),(8C,126.3),(2C,126.6),(4C,128.3),(2C,130.1),(2C,131.9),(1C,136),(2C,136.6),(2C,161.8)。

example 8

The preparation equation is as follows:

the method comprises the following steps:

to the reaction flask were added h-1(57.71mg,0.126mmol), 7.4mL dry K₂CO₃(134.0mg,0.970mmol),n-Bu₄NHSO₄(82mg,0.24mmol) and Pd (OAc)₂(5.4mg,0.025mmol) was stirred at 122 ℃ for 51 h. Cooling, toluene removal, addition of dichloromethane, water washing, drying, column chromatography of the crude product, using hexane/ethyl acetate (10:1) as eluent, final purification gives compound h-2.

The final product was determined to be MS: 458;

13C-NMR：(2C,109.4),(2C,113.3),(2C,115.5),(1C,124.1),(2C,125.7),(2C,126.6),(2C,127.0),(1C,128.5),(2C,129.0),(2C,129.9),(2C,130.1),(2C,133.5),(1C,136.5),(1C,141.8),(1C,143.7),(1C,145.1),(1C,152.5),(2C,159.9),(1C,162.1)。

LUMO energy level and thermal stability test method:

the final products of examples 1 to 8 described above 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 calculated from the relationship between HOMO, LUMO and Eg, specifically: LUMO HOMO + Eg) and a thermal stability test (thermogravimetric analysis TGA test step: sample mass 2 to 5mg, test temperature range 50 to 600 ℃, temperature increase rate: 10 ℃/min, taking 0.5% weight loss as representative of thermal stability of the material), and the test results are shown in table 1 below:

table 1: EXAMPLES product energy levels and thermal stability

Product source	Lumo energy level (eV)	Thermal stability (. degree. C.)
			Example 1	5.36	368
Example 2	5.29	384
			Example 3	5.35	379
Example 4	5.23	421
			Example 5	5.42	354
Example 6	5.22	407
			Example 7	5.18	411
Example 8	5.20	362

As can be seen from the above table, the more electron-withdrawing groups, such as fluorine atoms, are contained in the fulvic structure, the better the hole injection property of the compound is, and meanwhile, the stronger the electron-withdrawing property of the connected group is, the stronger the reduction potential of the compound is, the lower the LUMO energy level is; the rigidity of the molecule is increased, and the thermal stability of the molecule can be improved.

Therefore, the compound having a fullerene-rich structure in the embodiment of the present invention has both good thermal stability and hole injection property.

Control test

Examples 1 to 8

Light-emitting element structures 1 to 8 were prepared from the products prepared in examples 1 to 8 of the present invention, respectively:

the transparent anode electrode ITO substrate was ultrasonically cleaned in isopropanol for 10min and exposed to ultraviolet light for 30min, followed by plasma treatment for 10 min. And then putting the processed ITO substrate into evaporation equipment.

Firstly, a layer of NPB with the thickness of 50nm is mixed and evaporatedAnd the hole-injecting materials prepared in examples 1 to 8 of the present invention (the molar ratio of the hole-injecting material and NPB prepared in examples 1 to 8 was 1:33.3, the hole-injecting layer), followed by vapor deposition of NPB with a film thickness of 30nm on the mixed film layer, and then mixed vapor deposition of CBPAnd 5% of Ir (ppy)₃ The film thickness was 30nm (light-emitting layer), and then 30nm of Alq was evaporated₃(8-HydroxyquinolinylaluminumElectron transport layer), then 2nm LiF (electron injection layer) is evaporated, and finally 150nm metal Al is evaporated to form a metal cathode, thereby manufacturing the organic light emitting devices 1 to 8 according to the embodiments of the present invention.

The organic light-emitting elements 1 to 8 prepared based on examples 1 to 8 of the present invention had the structures:

ITO/NPB hole injection Material/NPB/CBP of examples 1-8 Ir (ppy)₃/Alq₃/LiF/Al。

Comparative example 1

The differences from the organic light-emitting elements 1 to 8 prepared in examples 1 to 8 are: the same applies to examples 1 to 8, in which only one layer of 50nm NPB was deposited, without performing hybrid deposition of the hole injection material, when one layer of 50nm NPB and one layer of the hole injection material of examples 1 to 8 were mixed deposited.

The structure of the organic light emitting element 9 prepared in comparative example 1 was:

ITO/NPB/CBP:Ir(ppy)₃/Alq₃/LiF/Al。

comparative example 2

The differences from the organic light-emitting elements 1 to 8 prepared in examples 1 to 8 are: in the case of mixed evaporation of NPB of 50nm in one layer in examples 1 to 8 and the hole injection materials in examples 1 to 8, a radialene compound was usedThe same applies to the hole injection materials of examples 1 to 8.

The structure of the organic light emitting element 10 prepared in comparative example 2 was:

ITO/NPB Axis Compound/CBP Ir (ppy)₃/Alq₃/LiF/Al。

Performance testing

The organic light emitting elements 1 to 8 prepared in examples 1 to 8 of the present invention and the organic light emitting elements 9 to 10 prepared in comparative examples 1 to 2 were subjected to the following performance tests:

(1) driving voltage: the test method is to measure the current density of 10mA/cm²A lower drive voltage;

(2) service life: the test method is the half-life of the luminescence at an initial brightness of 1000nits at 25 ℃.

The test results are shown in table 2:

table 2: comparison of Driving Voltage and half-Life

As can be seen from the results of table 2, the organic light emitting devices 1 to 8 formed a hole injection layer by doping the hole injection material prepared in examples 1 to 8, and thus, the driving voltage was lower than that of the organic light emitting device 9. The reason is that the hole injection materials prepared in embodiments 1 to 8 of the present invention have strong electron-withdrawing groups, and the molecules have strong reduction potentials by matching with cross-conjugated pi bonds, so as to assist the hole transport layer to efficiently inject holes, so that holes can appear in a larger area, form free holes, and obtain a higher hole extraction rate.

Meanwhile, compared with the organic light-emitting element 10, the organic light-emitting elements 1-8 have better thermal stability due to the doping of the hole injection materials prepared in the embodiments 1-8, and the service life of the device is prolonged.

In summary, the hole injection material and the organic electroluminescent device having the same have good cross-over super-conjugation characteristics, and can give a strong reduction potential to a molecule by combining with a strong electron-absorbing group such as a cyano group and a fluorine group, thereby assisting a hole transport layer to efficiently inject holes. Meanwhile, the hole injection material disclosed by the invention has good thermal stability and good film-forming property.

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.