阅读说明：本技术 具有空穴阻挡层的有机电致发光器件 (Organic electroluminescent device with hole blocking layer ) 是由 李轶文 邢其锋 吴俊宇 邵爽 于 2018-08-22 设计创作，主要内容包括：本发明提供一种有机电致发光器件,包含阴极、电子传输层、空穴传输层、空穴阻挡层、发光层、和阳极,所述空穴阻挡层包含一种或多种式(I)所示的化合物：<Image he="1000" wi="673" file="DDA0001773637080000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>其中,L<Sup>1</Sup>、L<Sup>2</Sup>和L<Sup>3</Sup>分别独立地选自单键、C<Sub>1</Sub>-C<Sub>12</Sub>的亚烷基、C<Sub>1</Sub>-C<Sub>8</Sub>的亚烷氧基、C<Sub>6</Sub>-C<Sub>30</Sub>的亚芳基、C<Sub>5</Sub>-C<Sub>30</Sub>的含氮亚杂芳基；Ar<Sup>1</Sup>、Ar<Sup>2</Sup>和Ar<Sup>3</Sup>分别独立地选自C<Sub>6</Sub>-C<Sub>30</Sub>的芳基、C<Sub>5</Sub>-C<Sub>30</Sub>的杂芳基,Ar<Sup>1</Sup>可以取代于它连接的苯环的任意取代位点,当L<Sup>1</Sup>、L<Sup>2</Sup>、L<Sup>3</Sup>、Ar<Sup>1</Sup>、Ar<Sup>2</Sup>、Ar<Sup>3</Sup>中的任意一个或几个具有取代基时,所述取代基独立地选自卤素、C<Sub>1</Sub>-C<Sub>10</Sub>的烷基或环烷基、烯基、C<Sub>1</Sub>-C<Sub>6</Sub>的烷氧基或硫代烷氧基、C<Sub>6</Sub>-C<Sub>30</Sub>的芳基、含有选自N、O、S、Si的杂原子且C<Sub>6</Sub>-C<Sub>30</Sub>的芳基；X选自O、S或Se。(The invention provides an organic electroluminescence deviceA light-emitting device comprising a cathode, an electron-transporting layer, a hole-blocking layer, a light-emitting layer, and an anode, the hole-blocking layer comprising one or more compounds of formula (I): wherein L is 1 、L 2 And L 3 Each independently selected from the group consisting of a single bond, C 1 ‑C 12 Alkylene of (C) 1 ‑C 8 Alkylene oxide of (A), C 6 ‑C 30 Arylene of, C 5 ‑C 30 The nitrogen-containing heteroarylene of (1); ar (Ar) 1 、Ar 2 And Ar 3 Are each independently selected from C 6 ‑C 30 Aryl of (C) 5 ‑C 30 Heteroaryl of Ar 1 Can be substituted at any substitution site of the benzene ring to which it is attached, when L is 1 、L 2 、L 3 、Ar 1 、Ar 2 、Ar 3 When any one or more of them has a substituent, the substituent is independently selected from halogen and C 1 ‑C 10 Alkyl or cycloalkyl, alkenyl, C 1 ‑C 6 Alkoxy or thioalkoxy of C 6 ‑C 30 Aryl radical of (a) C containing a heteroatom selected from N, O, S, Si 6 ‑C 30 Aryl of (a); x is selected from O, S or Se.)

1. An organic electroluminescent device comprising a cathode, an electron transport layer, a hole blocking layer, a light emitting layer, and an anode, the hole blocking layer comprising one or more compounds of formula (I):

wherein L is¹、L²And L³Each independently selected from the group consisting of a single bond, C₁-C₁₂Alkylene of (C)₁-C₈Alkylene oxide of (A), C₆-C₃₀Substituted or unsubstituted arylene of, C₅-C₃₀Substituted or unsubstituted nitrogen-containing heteroarylene of (a);

Ar¹、Ar²and Ar³Are each independently selected from C₆-C₃₀Substituted or unsubstituted aryl of (1), C₅-C₃₀Substituted or unsubstituted heteroaryl of, Ar¹Can be substituted at any substitution site of the benzene ring to which it is attached,

when L is¹、L²、L³、Ar¹、Ar²、Ar³When any one or more of them has a substituent, the substituent is independently selected from halogen and C₁-C₁₀Alkyl or cycloalkyl, alkenyl, C₁-C₆Alkoxy or thioalkoxy of C₆-C₃₀Aryl radical of (a) C containing a heteroatom selected from N, O, S, Si₆-C₃₀Aryl of (a);

x is selected from O, S or Se.

2. The organic electroluminescent device according to claim 1, wherein the compound of formula (I) has a HOMO > 5.6eV, a LUMO < 2.9eV, and a T1 level > 2.5 eV.

3. The organic electroluminescent device according to claim 1, wherein the hole blocking layer has a thickness of 0.3nm to 20nm, preferably 0.5nm to 10nm, and more preferably 5nm to 10 nm.

4. The organic electroluminescent device according to claim 1, wherein in the formula (I), L¹、L²And L³Each independently selected from a single bond, or a group selected from phenylene, biphenylene, pyridylene, pyrimidylene and pyrazinylene which may have a substituent, or any combination of these groups, as the substituent, selected from halogen and C₁-C₁₀Alkyl or cycloalkyl, alkenyl, C₁-C₆Alkoxy or thioalkoxy of C₆-C₂₀Aryl radical of (a) C containing a heteroatom selected from N, O, S, Si₆-C₂₀Aryl group of (1).

5. The organic electroluminescent device according to claim 1, wherein in the formula (I), L¹And L²Is a single bond, L³Selected from a single bond or a group wherein the dotted line drawn through the aromatic ring indicates that the bondable position of the aromatic ring may serve as a linking site:

6. the organic electroluminescent device according to claim 4, wherein in the formula (I), L¹And L²Is a single bond, L³Selected from a single bond or a group wherein the dotted line drawn through the aromatic ring indicates that the bondable position of the aromatic ring may serve as a linking site:

7. the organic electroluminescent element as claimed in claim 1, wherein in the formula (I), Ar¹、Ar²And Ar³Each independently selected from phenylBiphenyl, terphenyl, naphthyl, phenanthryl, benzophenanthryl, pyridyl, pyrimidinyl, quinolinyl, isoquinolinyl, pyrazinyl, fluorenyl, spirofluorenyl, phenanthrolinyl, dibenzothiapyrrol, and any combination thereof, preferably Ar¹Selected from the group consisting of terphenyl, naphthyl, phenanthryl, benzophenanthryl, pyridyl, pyrimidinyl, quinolinyl, quinoxalinyl, isoquinolinyl, pyrazinyl, fluorenyl, spirofluorenyl, dibenzothiapyrrolyl, phenanthrolinyl, and any combination thereof.

8. The organic electroluminescent device according to claim 1, wherein the content of the compound represented by formula (I) is 10% to 100%, preferably 30% to 100%, more preferably 40% to 80% of the entire hole blocking layer.

9. The organic electroluminescent device according to claim 8, when the content of the compound represented by formula (I) in the hole blocking layer is not 100%, the hole blocking layer further comprises other compounds as a dopant selected from the group consisting of:

10. an organic electroluminescent device according to any one of claims 1 to 9, wherein the compound represented by formula (I) is one of the following compounds:

11. the organic electroluminescent device according to claim 1, further comprising a hole injection layer.

12. The organic electroluminescent device according to claim 1, further comprising an electron blocking layer.

Technical Field

The invention relates to the field of organic electroluminescent materials, in particular to an organic electroluminescent device with a hole blocking layer.

Background

The basic structure and technology of Organic Light-Emitting Diodes (OLEDs) was first discovered by professor dungeon (china w.tang) in 1979 in kodak corporation. The OLED technology has the advantages of self-luminescence, wide viewing angle, high contrast, low power consumption, fast response speed, etc., and is widely applied to high-end products in the fields of flat panel display, lamp illumination, micro-display, etc. Since the OLED has a unique multi-layer organic film structure, the construction of thin film materials with different functional layers is always the research focus of the OLED industry, which restricts the production process and application range of OLED products and affects the industrialization process of OLED products in the fields of display, illumination and the like.

In a plurality of functional layers of the organic electroluminescent device, the hole blocking layer is generally applied between the light emitting layer and the electron transport layer to play a role in connecting the light emitting layer and the electron transport layer, so that the potential barrier of electron transport can be effectively reduced, the electron injection performance can be enhanced, meanwhile, the transfer of excitons and holes in the light emitting layer can be blocked, and the occurrence of leakage current can be reduced. In the OLED structure with the multiple light-emitting layers, the hole blocking layer can control the light-emitting state of the light-emitting layer by controlling the material properties and the film thickness. Therefore, the method has very important significance for the practical application of the OLED.

Disclosure of Invention

Problems to be solved by the invention

With the development of organic electroluminescent devices, the demand for them is also increasing. By increasing the number of organic layers in the OLED device and building an ideal energy level structure, the efficiency of the device can be effectively improved, the driving voltage of the device can be reduced, and the like, for example, a hole blocking layer is added between a light emitting layer and an electron transporting layer, however, the HOMO and LUMO energy levels and the triplet T1 energy levels of the hole blocking layer material are strictly limited, and the material is required to have good stability. At present, common hole blocking layers of organic electroluminescent devices, such as TPBi or R1, have good energy levels but poor stability, which further affects the lifetime of the devices. There is therefore room for great improvement in the properties of hole transport materials.

Means for solving the problems

As a result of intensive studies, the inventors of the present invention have designed an organic electroluminescent device using a novel organic compound as a hole blocking layer material. According to the material, the dibenzothiophene bridged triazine derivative is introduced to serve as a mother core structure, and the dibenzothiophene bridged triazine derivative and the mother core formed by bridging the dibenzothiophene bridged triazine derivative and the mother core in different modes can reduce the migration of holes and excitons from a light emitting layer to an electron transport layer, so that the efficiency of a device is improved, and the stability of the device is improved.

Specifically, the invention provides an organic electroluminescent device comprising a cathode, an electron transport layer, a hole blocking layer, a light emitting layer, and an anode, the hole blocking layer comprising one or more compounds represented by formula (I):

wherein L is¹、L²And L³Each independently selected from the group consisting of a single bond, C₁-C₁₂Alkylene of (C)₁-C₈Alkylene oxide of (A), C₆-C₃₀Substituted or unsubstituted arylene of, C₅-C₃₀Substituted or unsubstituted nitrogen-containing heteroarylene of (a); ar (Ar)¹、Ar²And Ar³Are each independently selected from C₆-C₃₀Substituted or unsubstituted aryl of (1), C₅-C₃₀Substituted or unsubstituted heteroaryl of, Ar¹Can be substituted at any substitution site of the benzene ring to which it is attached, when L is¹、L²、L³、Ar¹、Ar²、Ar³When any one or more of them has a substituent, the substituent is independently selected from halogen and C₁-C₁₀Alkyl or cycloalkyl, alkenyl, C₁-C₆Alkoxy or thioalkoxy of C₆-C₃₀Aryl radical of (a) C containing a heteroatom selected from N, O, S, Si₆-C₃₀Aryl of (a); x is selected from O, S or Se.

When each of the above groups has a substituent, the number of carbons does not include the number of carbons of the substituent; aryl, arylene, heteroaryl, heteroarylene, all including no single ring, but also including fused rings; alkyleneoxy groups include both oxygen on the backbone and oxygen on the side chains.

The inventors found that by mixing L¹、L²And L³The organic electroluminescent device prepared by connecting dibenzothiophene (or dibenzofuran or dibenzoselenocyclopentadiene) and triazine derivative as parent nucleus in different modes has high efficiency and long service life. The principle is not clear, presumably because dibenzothiophene has a stable rigid structure, and triazine derivatives are good electron transport groups, both of which have high triplet energyThe organic electroluminescent device has the advantages that the organic electroluminescent device has high service life due to the fact that the organic electroluminescent device has excellent stability and the organic electroluminescent device has high stability. Furthermore, the inventors believe that Ar attached to the parent nucleus via a bridged benzene ring¹The structure may contribute to the formation of a stable pi system, which leads to an improvement in the stability of the compound, or may contribute to the provision of a hole-blocking layer having high stability, which leads to the prolongation of the lifetime of the device, since the structure makes the steric conformation of the compound more suitable for film formation.

In the above organic electroluminescent device, the compound represented by the formula (I) preferably has a HOMO > 5.6eV, a LUMO < 2.9eV, and a T1 level > 2.5 eV.

By limiting the HOMO, LUMO, and T1 energy levels of the compound represented by formula (I) to the above ranges, the diffusion of holes can be more effectively suppressed, the barrier for electron transport can be reduced, and the electron injection performance can be enhanced, so that the efficiency of an organic electroluminescent device fabricated using the compound as a hole blocking layer material is further improved. Meanwhile, the inventors have found that the lifetime of the organic electroluminescent device can be improved by limiting the HOMO, LUMO and T1 energy levels of the compound represented by formula (I) to the above ranges.

In the above organic electroluminescent device, the thickness of the hole blocking layer is preferably 0.3nm to 20nm, more preferably 0.5nm to 10nm, and most preferably 5nm to 10 nm.

Further, in the formula (I), L is preferred¹、L²And L³Each independently selected from a single bond, or a group selected from phenylene, biphenylene, pyridylene, pyrimidylene and pyrazinylene, which may have a substituent, or any combination thereof, as the substituent, selected from halogen and C₁-C₁₀Alkyl or cycloalkyl, alkenyl, C₁-C₆Alkoxy or thioalkoxy of C₆-C₂₀OfRadical, containing a heteroatom selected from N, O, S, Si and C₆-C₂₀Aryl group of (1).

Further, in the formula (I), L¹And L²Preferably a single bond; l is³Preferably a single bond or the following groups:

wherein the dashed line drawn through the aromatic ring indicates that the bondable position of the aromatic ring can be used as a linking site, e.g., the two dashed lines drawn above on the pyridine ring, i.e., indicates that a linkage is formed at any two substitution sites of pyridine.

Further, in the formula (I), L³The above groups are preferred.

By mixing L¹And L²Is limited to a single bond and L³The organic electroluminescent device is further limited to the groups, namely the dibenzothiophene segment and the triazine segment are connected through different electron-withdrawing bridging groups to serve as a mother core, so that the luminous efficiency of the obtained organic electroluminescent device can be further improved. The principle is not clear, and it is presumed that this can improve the transport ability of electrons in the molecule of the compound, and that the molecule has a higher triplet level due to the distorted molecular structure, whereby the hole blocking ability is further improved, and the potential barrier for electron injection can be further reduced.

Further, Ar¹、Ar²And Ar³Preferably each independently selected from phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, benzophenanthryl, pyridyl, pyrimidinyl, quinolinyl, isoquinolinyl, pyrazinyl, fluorenyl, spirofluorenyl, phenanthrolinyl, dibenzothiapyrrol, and any combination thereof.

By introducing Ar¹、Ar²And Ar³The above groups are respectively used to further improve the hole blocking performance of the compound represented by the formula (I), thereby improving the service life of the organic electroluminescent device.

Further, Ar¹More preferably selected from terphenyl, naphthyl, phenanthrylBenzophenanthryl, pyridyl, pyrimidinyl, quinolinyl, quinoxalinyl, isoquinolinyl, pyrazinyl, fluorenyl, spirofluorenyl, dibenzothiapyrrolyl, phenanthrolinyl, and any combination thereof.

Ar¹The reason why the above groups are preferred is that the inventors found that Ar is substituted in comparison with monocyclic aryl and aliphatic hydrocarbon groups¹When the above group is used, the stability of the obtained compound is greatly improved, and the life of the obtained device is further increased when the compound is used for an organic electroluminescent device. The principle is not clear, and it is presumed that the group is linked to dibenzothiophene via a bridged benzene ring, which is advantageous in forming a stable pi system and further improving the stability of the compound, and that the group makes the steric conformation of the compound more suitable for film formation, and therefore, a hole blocking layer having higher stability can be provided, which is advantageous in extending the life of the device.

Further, X is preferably O and S, more preferably S.

Further, Ar linked by bridged benzene rings¹Preferably in meta relationship to the dibenzothiophene group.

The inventor finds that a benzene ring is introduced at the adjacent position of the other end of dibenzothiophene as a bridging group, and a substituent group Ar is introduced at the meta position of the bridging benzene ring¹The luminous efficiency and the service life of the obtained organic electroluminescent device are further improved. The reason is not clear, and it is presumed that the electron cloud distribution of the HOMO orbital in the molecule is reduced and the HOMO energy level is increased due to the fact that a meta-position substituent group structure of the bridged benzene ring is designed in the transport group, and when the compound is applied to a light emitting layer of an OLED device as a hole blocking layer material, the starting voltage of the device can be effectively reduced, joule heat in the operation of the device is reduced, and therefore fatal damage such as compound decomposition caused by joule heat in the device is reduced, and on the other hand, introduction of the substituent group in the meta position of the bridged benzene ring is beneficial to balancing carrier transport in the device.

Further, in the organic electroluminescent device, the hole blocking layer may be one of the compounds represented by formula (I) alone, two or more of them may be used simultaneously, or may be used by doping with other compounds, and the content of the compound represented by formula (I) is preferably 10% to 100%, preferably 30% to 100%, more preferably 40% to 80% of the mass of the entire hole blocking layer. The content of the compound represented by the formula (I) is referred to as a doping concentration, and since it is achieved by controlling the evaporation rate, it is common in the art to express the doping concentration as a ratio of the evaporation rate.

Further, in the above organic electroluminescent device, when the content of the compound represented by formula (I) in the hole blocking layer is not 100%, it is preferable that the hole blocking layer further comprises other compounds as a dopant selected from, but not limited to, the following compounds:

further, in the organic electroluminescent device, the thickness of the hole blocking layer is preferably 0.3nm to 20nm, more preferably 0.5nm to 10nm, and still more preferably 5nm to 10 nm.

Further, in the above organic electroluminescent device, the total thickness of all the organic layers is preferably 1nm to 1000nm, more preferably 50nm to 500 nm.

Further, the above compound in the organic electroluminescent device of the present invention is preferably one of the following compounds:

the above organic electroluminescent device preferably further comprises an electron injection layer.

The above organic electroluminescent device preferably further comprises an electron blocking layer.

When the compound of formula (I) of the present invention is used in the organic electroluminescent device, other materials may be used in combination in, for example, the light-emitting layer, the electron transport layer, the electron injection layer, etc. to obtain blue light, green light, yellow light, red light, or white light.

The specific layer materials described in this invention that can be used in organic light emitting devices can be used in combination with a variety of other materials present in the device. The materials described or referenced below are non-limiting examples of materials that can be used in combination with the compounds disclosed herein, and one skilled in the art can readily review the literature to identify other materials that can be used in combination.

Drawings

Fig. 1 is a schematic structural diagram of an organic electroluminescent device according to the present invention. Wherein 110 represents a glass substrate, 120 represents an anode, 130 represents a hole injection layer, 140 represents a hole transport layer, 150 represents a light emitting layer, 160 represents a hole blocking layer, 170 represents an electron transport layer, 180 represents an electron injection layer, and 190 represents a cathode.

FIG. 2 is the Highest Occupied Molecular Orbital (HOMO) of the compound of formula (I) according to the present invention.

FIG. 3 is the Lowest Unoccupied Molecular Orbital (LUMO) of a compound of formula (I) according to the present invention.

FIG. 4 is a thermogravimetric analysis of the compound represented by formula (I) of the present invention.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments in order to make the present invention better understood by those skilled in the art.