阅读说明：本技术 一种电子传输材料及有机电致发光器件 (Electron transport material and organic electroluminescent device ) 是由 黄雪明 于 2020-06-04 设计创作，主要内容包括：本发明提供了一种电子传输材料及有机电致发光器件,具有氮杂环结构的化合物。本发明的技术方案不仅具较高的稳定性,也具有高电荷转移能力和高玻璃化转变温度。(The invention provides an electron transport material and an organic electroluminescent device, which are compounds with nitrogen heterocyclic structures. The technical scheme of the invention not only has higher stability, but also has high charge transfer capacity and high glass transition temperature.)

1. An electron transport material, characterized by a compound having a structure represented by formula I:

wherein R is₁-R₄Independently of one another, hydrogen, deuterium, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 heteroaryl group, or a substituted or unsubstituted C1-C50 alkyl group.

2. The electron transport material of claim 1, wherein: the R is₁-R₄Each independently is phenyl, naphthyl, anthryl, phenanthryl, quinonyl, fluorenyl, spirofluorenyl, or furyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolinyl, isoquinolinyl, or methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolyl, isoquinolyl, orButyl, cyclopentyl, cyclohexyl, or combinations thereof.

3. The electron transport material of claim 1, wherein: the R is₁-R₄Each independently is a substituted or unsubstituted C6-C60 aryl group.

4. The electron transport material of claim 3, wherein: the R is₁-R₄Respectively and independently phenyl, naphthyl, anthryl, phenanthryl, quinonyl, fluorenyl and spirofluorenyl.

5. The electron transport material of claim 4, wherein: the compound of the structure shown in the formula I is:

6. the electron transport material of claim 1, wherein: the R is₁-R₄Is a combination of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C6-C60 heteroaryl group.

7. The electron transport material of claim 6, wherein: the R is₁-R₄Is a combination of phenyl, naphthyl, anthryl, phenanthryl, quinonyl, fluorenyl, spirofluorenyl and furyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolinyl, isoquinolinyl.

8. The electron transport material of claim 7, wherein: the compound of the structure shown in the formula I is:

9. the electron transport material of claim 1, wherein: the R is₁-R₄Each independently is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.

10. An organic electroluminescent device, characterized in that: the organic electroluminescent device doped with the electron transport material according to any one of claims 1 to 9.

Technical Field

The invention relates to the field of organic electroluminescent devices, in particular to an electron transport material and an organic electroluminescent device with the same.

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 an electron transport 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 lifetime of the device can be improved.

Of course, doping some strong oxidant into the hole transport layer as an electron transport layer is also another way to improve the electron transport efficiency of the organic electroluminescent device. However, this method has a requirement on the energy levels of the host material and the dopant material, and generally, the HOMO (Highest Occupied Molecular Orbital) energy level of the host material needs to be close to the 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 the hole transport layer forms free holes, thereby improving the conductivity of the device. Meanwhile, the doping can bend the interface energy band, and holes can be injected in a tunneling mode. As for the selection of the dopant, lewis acid type metal complexes, halogens, allenes and quinones are common, but the metal complexes and halogens have disadvantages such as instability in device processing. The allyl compounds have more steps in the synthesis and higher cost. Therefore, the method cannot improve the electron transport efficiency of the organic electroluminescent device well.

Therefore, the present invention provides a stable and efficient electron transport 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 an electron transport material and an organic electroluminescent device having the same, which have high stability, high charge transfer capability and high glass transition temperature.

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

wherein R is₁-R₄Independently of each other is hydrogenDeuterium, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 heteroaryl group, a substituted or unsubstituted C1-C50 alkyl group.

Preferably: the R is₁-R₄Each independently is phenyl, naphthyl, anthracenyl, phenanthrenyl, quinonyl, fluorenyl, spirofluorenyl, or furyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolinyl, isoquinolinyl, or methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or combinations thereof.

Preferably: the R is₁-R₄Each independently is a substituted or unsubstituted C6-C60 aryl group.

Preferably: the R is₁-R₄Respectively and independently phenyl, naphthyl, anthryl, phenanthryl, quinonyl, fluorenyl and spirofluorenyl.

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

preferably: the R is₁-R₄Is a combination of a substituted or unsubstituted C6-C60 aryl group and a substituted or unsubstituted C6-C60 heteroaryl group.

Preferably: the R is₁-R₄Is a combination of phenyl, naphthyl, anthryl, phenanthryl, quinonyl, fluorenyl, spirofluorenyl and furyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolinyl, isoquinolinyl.

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

preferably: the R is₁-R₄Are respectively independent from each other asAlkyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.

According to another aspect of the present invention, there is also provided an organic electroluminescent device doped with the above electron transport material.

The electron transport material and the organic electroluminescent device with the same have high stability, high charge transfer capacity and high glass transition temperature.

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 an electron transport material and an organic electroluminescent device having the same, the compound having a structure represented by formula I:

wherein R is₁-R₄Independently of one another, hydrogen, deuterium, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 heteroaryl group, or a substituted or unsubstituted C1-C50 alkyl group.

The electron transport material and the organic electroluminescent device with the same provided by the embodiment of the invention have the advantages of higher stability, high charge transfer capacity and high glass transition temperature.

The synthesis of the compound of formula I is as follows:

the synthesis of the compound structure of the general formula I comprises the following three steps:

1) compound 1(87.0mmol) and compound 2(87.0mmol) were suspended in 1, 4-dioxane (200mL) and acetic acid (20 mL). The resulting mixture was stirred and refluxed for about 6 hours, and cooled to normal temperature. The mixture was diluted with water (100mL), and the resulting solid was filtered and washed with water and ether to give compound 3.

2) Compound 3(5.10mmol), compound 4(5.10mmol), sodium tert-butoxide (6.01mmol) and Pd [ P (t-Bu)3]2(2 mol%) were suspended in toluene (50 mL). The resulting mixture was stirred and refluxed for about 6 hours, and cooled to normal temperature. Distilled water was added to the reaction solution to terminate the reaction, and the organic layer was extracted, dried over anhydrous magnesium sulfate, and then filtered. The filtrate was concentrated under reduced pressure and chromatographed at a tetrahydrofuran: hexane: 1:5 ratio to give compound 5.

3) Compound 5(152mmol) was dissolved in 300mL of dry THF (tetrahydrofuran) in a flask that had been dried by heating. The reaction mixture was cooled to-78 ℃. At this temperature, 75mL of a 15% solution of n-BuLi (119mmol) in hexane was slowly added dropwise over a period of about 1 hour. Then stirred at-70 ℃ for 1 hour. Compound 6(119mmol) was then dissolved in THF (100mL) and added dropwise at-70 ℃. When the addition is complete, the reaction mixture is slowly warmed to room temperature to bring the NH₄The Cl was quenched and then evaporated in a rotary evaporator. 510mL of acetic acid was slowly added to the evaporated solution, followed by 100mL of fuming hydrochloric acid. Then heated to 75 ℃ and held at this temperature for 4 hours, during which time a white solid precipitated. It was then cooled to room temperature and the precipitated solid was filtered off with suction and rinsed with methanol. The residue was dried under vacuum at 40 ℃ to give compound of formula I.

In an embodiment of the present invention, it is,

R₁-R₄preferably phenyl, naphthyl, anthracenyl, phenanthrenyl, quinonyl, fluorenyl, spirofluorenyl, or furyl, thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzofuryl, benzimidazolyl, quinolinyl, isoquinolinyl, or methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or combinations thereof.

Compounds of formula I are particularly preferably compound A, B, C, D, E below:

the following specific examples describe the invention:

example 1

The synthetic method for preparing compound a is the same as the synthetic method for preparing the compound of formula I. Wherein the structures of compounds 2, 3, 4, 5 and 6 are respectively

The yield of compound a was 82%. Characterization data: melting point (DSC)289 deg.C, purity 99.9%;¹H NMR(400MHz,CDCl₃)δ(ppm)：8.06(m,1H),7.80(s,1H),7.61(m,1H),7.56(m,1H),7.48(m,2H),7.44(m,1H),7.32(m,2H),7.30(m,5H),7.24(m,1H),7.22(m,1H),7.14(m,4H),7.08(m,2H),7.06(m,4H).

example 2

The synthetic method for preparing compound B is the same as the synthetic method for synthesizing the compound of formula I. Wherein the structures of compounds 2, 3, 4, 5 and 6 are respectively

The yield of compound B was 76%. Characterization data: melting point (DSC)342 ℃, purity 99.9%;¹H NMR(400MHz,CDCl₃)δ(ppm)：8.06(m,1H),7.80(s,1H),7.61(m,1H),7.56(m,1H),7.48(m,6H),7.44(m,1H),7.32(m,6H),7.24(m,1H),7.22(m,3H),7.14(m,4H),7.08(m,2H),7.06(m,4H).

example 3

The synthetic method for preparing compound C is the same as the synthetic method for synthesizing the compound of formula I. Wherein the structures of compounds 2, 3, 4, 5 and 6 are respectively

The yield of compound C was 79%. Characterization data: melting point (DSC) of 302 ℃ and purity of 99.9 percent;¹H NMR(400MHz,CDCl₃)δ(ppm)：8.41(m,2H),8.06(m,1H),7.80(s,1H),7.61(s,1H),7.56(m,1H),7.48(m,4H),7.44(m,1H),7.32(m,4H),7.30(m,5H),7.24(m,1H),7.22(m,2H),7.14(m,2H),7.08(m,1H),7.06(m,2H).

example 4

The synthetic method for preparing compound D is the same as the synthetic method for synthesizing the compound of formula I. Wherein the structures of compounds 2, 3, 4, 5 and 6 are respectively

The yield of compound D was 81%. Characterization data: melting Point (DSC)296 deg.CThe purity is 99.9%;¹H NMR(400MHz,CDCl₃)δ(ppm)：8.06(m,1H),7.80(s,1H),7.68(m,1H),7.64(m,1H),7.61(m,2H),7.56(m,1H),7.48(m,2H),7.46(m,1H),7.44(m,1H),7.32(m,2H),7.31(m,1H),7.30(m,5H),7.28(m,1H),7.24(m,1H),7.22(m,1H),7.18(d,1H),7.14(m,2H),7.08(m,1H),7.06(m,2H).

example 5

The synthetic method for preparing compound E is the same as the synthetic method for synthesizing the compound of formula I. Wherein the structures of compounds 2, 3, 4, 5 and 6 are respectively

The yield of compound E was 80%. Characterization data: melting point (DSC) of 321 ℃ and purity of 99.9 percent;¹H NMR(400MHz,CDCl₃)δ(ppm)：8.32(s,1H),8.28(s,1H),8.06(m,1H),7.91(m,2H),7.85(m,1H),7.80(s,1H),7.70(m,1H),7.61(s,1H),7.56(m,1H),7.48(m,2H),7.44(m,1H),7.39(m,2H),7.32(m,2H),7.30(m,5H),7.25(m,1H),7.24(m,1H),7.22(m,1H),7.14(m,2H),7.08(m,1H),7.06(m,2H).

control test

Examples 1 to 5

Organic light-emitting elements 1 to 5 were produced from the products produced in examples 1 to 5 of the present invention, respectively.

The organic light emitting element 1-5 includes an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode in this order from bottom to top.

The electron transport layer included host materials and guest materials, and the host materials were the compounds prepared in examples 1 to 5.

The constituent materials of the layers were as follows:

anode: ITO (indium tin oxide) with a thickness of 80 nm;

hole injection layer: the material comprises a host material NPB and a guest material F4-TCNQ, wherein the mole percentage content of the guest material is 3%; the thickness of the hole injection layer is 10 nm;

hole transport layer: NPB with thickness of 110 nm;

light-emitting layer: a host material TCTA and a guest material Ir (ppy)3, wherein the molar percentage content of the guest material is 6%; the thickness is 40 nm;

electron transport layer: the thickness is 40nm, and the host material and the guest material and the molar percentage content thereof are shown in the following table 1;

cathode: Mg/Ag with a thickness of 20 nm.

TABLE 1

Serial number	Host and guest materials for electron transport layers
		Organic light emitting element 1	The compound A (50%) comprises LiQ (50%)
Organic light emitting element 2	The compound B (50%) comprises LiQ (50%)
		Organic light emitting element 3	The compound C (50%) is LiQ (50%)
Organic light emitting element 4	Compound D (50%) LiQ (50%)
		Organic light emitting element 5	Compound E (50%) LiQ (50%)

In the above organic light emitting element 1-5, the structural formula corresponding to the abbreviation of the material is as follows:

comparative example 1

An organic light-emitting element 6 was prepared. The differences from the organic light-emitting elements 1 to 5 prepared in examples 1 to 5 are: the material of the electron transport layer in the organic light emitting element 6 was BPhen (50%): LiQ (50%), and the rest was the same.

Performance testing

The organic light-emitting elements 1 to 5 prepared in examples 1 to 5 of the present invention and the organic light-emitting element 6 prepared in comparative example 1 were subjected to the following performance tests:

the test items include current efficiency (LE), driving voltage (V), and lifetime (LT95, time for luminance to decay to 95%).

Wherein the device performance (LE, V) data is measured at a luminance of 1000nits and the lifetime (LT95) data is measured at a current density of 30mA/cm²Calculated under the condition.

The performance test results are shown in table 2:

TABLE 2

Item	Color of light emission	LE(Cd/A)	V(V)	LT95(hr)
					Organic light emitting element 1	Green colour	64	6.6	112
Organic light emitting element 2	Green colour	91	5.0	102
					Organic light emitting element 3	Green colour	68	5.8	135
Organic light emitting element 4	Green colour	70	5.5	186
					Organic light emitting element 5	Green colour	76	5.3	204
Organic light emitting element 6	Green colour	48	7.2	72

As can be seen from the performance data of table 2, the materials of the embodiments of the present invention are highly suitable for use as electron transport materials in OLED devices and have very good electron transport properties. Compared with the BPhen material of the comparative example, the material of the embodiment of the invention has higher efficiency (not lower than 64Cd/A), lower voltage (not higher than 6.6V) and longer service life (not lower than 102 h).

In conclusion, the electron transport material and the organic electroluminescent device with the same have high stability, high charge transfer capacity and high glass transition temperature.

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.