KR102268119B1 - Pyrene compound and organic light emitting diode device comprising the same - Google Patents

Abstract

[화학식 2]

상기 화학식 1 및 2에서, X는 C, N, S, O를 하나 또는 그 이상을 포함한 아릴, 방향족 화합물, 헤테로 아릴, 헤테로 방향족 화합물이고, R₁은 치환되거나 치환되지 않은 알킬, 아릴, 헤테로 아릴, 방향족 화합물, 헤테로 방향족 화합물, 아릴 아민 및 헤테로 아릴 아민으로 이루어진 군에서 선택된 어느 하나이고, n은 1 내지 4의 정수이며, 상기 화학식 2에서 상기 R₂는 치환되거나 치환되지 않은 알킬, 아릴, 헤테로 아릴, 방향족 화합물, 헤테로 방향족 화합물, 아릴 아민 및 헤테로 아릴 아민으로 이루어진 군에서 선택된 어느 하나이다.The pyrene compound according to an embodiment of the present invention is characterized in that it is represented by the following Chemical Formula 1 or 2.
[Formula 1]

[Formula 2]

In Formulas 1 and 2, X is an aryl, aromatic compound, heteroaryl, or heteroaromatic compound containing one or more C, N, S, and O, and R ₁ is substituted or unsubstituted alkyl, aryl, heteroaryl , an aromatic compound, a heteroaromatic compound, any one selected from the group consisting of arylamine and heteroarylamine, n is an integer from 1 to 4, wherein R ₂ is substituted or unsubstituted alkyl, aryl, hetero Any one selected from the group consisting of aryl, aromatic compounds, heteroaromatic compounds, arylamines and heteroarylamines.

Description

Pyrene compound and organic electroluminescent device comprising same {PYRENE COMPOUND AND ORGANIC LIGHT EMITTING DIODE DEVICE COMPRISING THE SAME}

The present invention relates to a pyrene compound and an organic electroluminescent device including the same, and more particularly, to a pyrene compound capable of improving luminous efficiency and lifespan and lowering a driving voltage of an organic electroluminescent device, and an organic electroluminescent device comprising the same It's about the little ones.

A video display device that implements various information on a screen is a key technology in the information and communication era, which is developing in the direction of thinner, lighter, more portable and high-performance. With the recent development of the information society, as the demand for various types of display devices increases, LCD (Liquid Crystal Display), PDP (Plasma Display Panel), ELD (Electro Luminescent Display), FED (Field Emission Display), OLED ( Organic Light Emitting Diode) and other flat panel display devices are being actively researched.

Among them, the organic light emitting device is a device that emits light while electrons and holes are paired and then disappear when electric charges are injected into the organic light emitting layer formed between the anode and the cathode. The organic electroluminescent device can be formed on a flexible transparent substrate such as plastic, and can be driven at a lower voltage than a plasma display panel or an inorganic electroluminescent (EL) display, and power consumption is relatively low. It has the advantage of being small and the color is excellent. In particular, the organic electroluminescent device for realizing white color is a device that is used for various purposes, such as a thin light source, a backlight of a liquid crystal display device, or a full-color display device employing a color filter as well as lighting.

In the development of white organic light emitting diodes, research and development are in progress according to each method because high efficiency and long lifespan, as well as color purity, color stability according to changes in current and voltage, and ease of device manufacturing are important. There are various structures of the white organic light emitting device, and it can be broadly divided into a single layer light emitting structure, a multilayer light emitting structure, and the like. Among them, a multilayer light emitting structure in which a fluorescent blue light emitting layer and a phosphorescent yellow light emitting layer are stacked (tandem) is mainly adopted for a long-life white device.

Specifically, a phosphorescent stack structure in which a first stack using a blue fluorescent device as a light emitting layer and a second stack structure using a yellow-green phosphor as a light emitting layer are stacked is used. In such a white organic light emitting device, white light is realized by a mixing effect of blue light emitted from a blue fluorescent device and yellow light emitted from a yellow phosphorescent device. Here, a charge generation layer is provided between the first stack and the second stack to double the efficiency of the current generated in the light emitting layer and to facilitate charge distribution. The charge generation layer is a layer that generates electric charges, that is, electrons and holes inside, doubles the efficiency of current generated in the light emitting layer, and facilitates charge distribution, thereby preventing the driving voltage from being increased.

However, in the conventional charge generation layer, the N-type charge generation layer and the P-type charge generation layer have a PN junction structure. Due to the energy level difference between the N-type charge generation layer and the P-type charge generation layer, the P-type charge generation layer is adjacent to the P-type charge generation layer Due to the charge generation at the hole injection layer interface, the electron injection property into the N-type charge generation layer is deteriorated. In addition, when the N-type charge generation layer is doped with an alkali metal, the alkali metal diffuses into the P-type charge generation layer, thereby reducing the lifetime of the device.

The present invention provides a pyrene compound capable of improving the luminous efficiency and lifespan of the organic light emitting device and lowering the driving voltage, and an organic light emitting device including the same.

In order to achieve the above object, the pyrene compound according to an embodiment of the present invention is characterized in that it is represented by the following Chemical Formula 1 or 2.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, X is an aryl, aromatic compound, heteroaryl, or heteroaromatic compound containing one or more C, N, S, and O, and R ₁ is substituted or unsubstituted alkyl, aryl, heteroaryl , aromatic compound, heteroaromatic compound, any one selected from the group consisting of arylamine and heteroarylamine, n is an integer from 1 to 4, wherein R ₂ is substituted or unsubstituted alkyl, aryl, hetero Any one selected from the group consisting of aryl, aromatic compounds, heteroaromatic compounds, arylamines and heteroarylamines.

The pyrene compound is characterized in that any one selected from the compounds shown below.

In addition, the organic light emitting diode according to an embodiment of the present invention is formed between an anode and a cathode, and includes a first stack including a blue light emitting layer, a second stack including a yellow light emitting layer, and the first stack and the second stack In the organic electroluminescent device including a charge generation layer positioned between stacks, the charge generation layer is characterized in that it includes the pyrene compound.

The charge generation layer includes an N-type charge generation layer and a P-type charge generation layer, wherein the N-type charge generation layer includes the pyrene compound.

The first stack further includes a hole injection layer and a hole transport layer between the anode and the blue emission layer, and further includes an electron transport layer between the blue emission layer and the charge generation layer.

The second stack further includes a hole transport layer between the charge generation layer and the yellow emission layer, and further includes an electron transport layer and an electron injection layer between the yellow emission layer and the cathode.

The pyrene compound and the organic electroluminescent device including the same according to an embodiment of the present invention have the advantage of improving the driving voltage, current efficiency, color coordinates and lifespan characteristics of the organic electroluminescent device.

1 is a view showing an organic electroluminescent device according to an embodiment of the present invention.
Figure 2 is a graph showing the measurement of the current density according to the driving voltage of the organic light emitting device manufactured according to an embodiment of the present invention.
3 is a graph showing the reduction rate of luminance according to time of an organic light emitting diode manufactured according to an embodiment of the present invention.
4 is a graph showing the measurement of the emission spectrum of the organic light emitting device manufactured according to an embodiment of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing an organic electroluminescent device according to an embodiment of the present invention.

Referring to FIG. 1 , in the organic light emitting device 100 of the present invention, stacks ST1 and ST2 positioned between an anode 110 and a cathode 210 and charges positioned between stacks ST1 and ST2 and a generation layer 160 . The anode 110 is an electrode for injecting holes and may be any one of indium tin oxide (ITO), indium zinc oxide (IZO), and zinc oxide (ZnO) having a high work function. In addition, when the anode 110 is a reflective electrode, the anode 110 includes a reflective layer made of any one of aluminum (Al), silver (Ag), or nickel (Ni) under the layer made of any one of ITO, IZO, and ZnO. may include more.

The first stack ST1 constitutes one light emitting device unit, and includes a hole injection layer 120 , a first hole transport layer 130 , a blue light emitting layer 140 , and a first electron transport layer 150 .

The hole injection layer 120 may serve to smoothly inject holes from the anode 110 to the blue light emitting layer 140 , and may include cupper phthalocyanine (CuPc), poly(3,4)-ethylenedioxythiophene (PEDOT), and PANI. (polyaniline) and NPD (N,N-dinaphthyl-N,N'-diphenyl benzidine) may consist of any one or more selected from the group consisting of, but is not limited thereto. The hole injection layer 120 may have a thickness of 1 to 150 nm. Here, if the thickness of the hole injection layer 120 is 1 nm or more, there is an advantage in that the hole injection characteristics are prevented from being deteriorated, and if it is 150 nm or less, the thickness of the hole injection layer 120 is too thick to prevent the movement of holes. There is an advantage in that it is possible to prevent the driving voltage from being increased in order to improve it.

The first hole transport layer 130 serves to facilitate hole transport, and NPD (N,N-dinaphthyl-N,N'-diphenyl benzidine), TPD (N,N'-bis-(3-methylphenyl) )-N,N'-bis-(phenyl)-benzidine), s-TAD and MTDATA(4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine) may be made of any one or more selected from, but is not limited thereto. The thickness of the first hole transport layer 130 may be 1 to 150 nm. Here, if the thickness of the first hole transport layer 130 is 5 nm or more, the hole There is an advantage that the transport characteristics can be prevented from being lowered, and when it is 150 nm or less, the thickness of the first hole transport layer 130 is too thick, and there is an advantage that the driving voltage can be prevented from increasing to improve hole movement. .

The blue light emitting layer 140 may include a host material including CBP or mCP, and may be formed of a phosphor material including a dopant material including _{(4,6-F 2} ppy) _{2 Irpic.} DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), may be made of a fluorescent material including any one selected from the group consisting of PFO-based polymers and PPV-based polymers, but is not limited thereto.

The first electron transport layer 150 serves to facilitate the transport of electrons, and is made of at least one selected from the group consisting of Alq3 (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. may be made, but is not limited thereto. The thickness of the first electron transport layer 150 may be 1 to 50 nm. Here, if the thickness of the first electron transport layer 150 is 1 nm or more, there is an advantage that can prevent the electron transport properties from being lowered, and if it is 50 nm or less, the thickness of the first electron transport layer 150 is too thick, so the electrons are moved There is an advantage in that it is possible to prevent the driving voltage from being increased in order to improve . Accordingly, the first stack ST1 including the hole injection layer 120 , the first hole transport layer 130 , the blue light emitting layer 140 , and the first electron transport layer 150 is formed on the anode 110 .

A charge generation layer (CGL) 160 is positioned on the first stack ST1 . The charge generation layer 160 may be a PN junction charge generation layer in which the N-type charge generation layer 160N and the P-type charge generation layer 160P are joined. At this time, the PN junction charge generation layer 160 generates charges or separates them into holes and electrons to inject charges into each of the light emitting layers. That is, the N-type charge generation layer 160N supplies electrons to the blue light-emitting layer 140 adjacent to the anode, and the P-type charge generation layer 160P supplies holes to the light-emitting layer of the second stack ST2. It is possible to further increase the luminous efficiency of the organic electroluminescent device having the light emitting layer of the emitting layer, and also to lower the driving voltage.

Here, the N-type charge generation layer 160N may be formed of a pyrene compound represented by the following Chemical Formula 1 or 2.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, X is an aryl, aromatic compound, heteroaryl, or heteroaromatic compound containing one or more C, N, S, and O, and R ₁ is substituted or unsubstituted alkyl, aryl, heteroaryl , an aromatic compound, a heteroaromatic compound, any one selected from the group consisting of arylamine and heteroarylamine, n is an integer from 1 to 4, wherein R ₂ is substituted or unsubstituted alkyl, aryl, hetero It may be any one selected from the group consisting of aryl, aromatic compound, heteroaromatic compound, arylamine and heteroarylamine.

The above-mentioned pyrene compound may be any one selected from among the compounds shown below.

The P-type charge generation layer 160P may be formed of a metal or an organic material doped with P-type. Here, the metal may be made of one or two or more alloys selected from the group consisting of Al, Cu, Fe, Pb, Zn, Au, Pt, W, In, Mo, Ni and Ti. In addition, as the P-type dopant and the host material used in the P-type doped organic material, a commonly used material may be used. For example, the P-type dopant may include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), a derivative of tetracyanoquinodimethane, iodine , FeCl ₃ , FeF ₃ and SbCl _{5 It} may be one material selected from the group consisting of. In addition, the host is N,N'-di(naphthalen-1-yl)-N,N-diphenyl-benzidine (NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl) It may be one material selected from the group consisting of -1,1-biphenyl-4,4'-diamine (TPD) and N,N',N'-tetranaphthyl-benzidine (TNB).

On the other hand, the second hole transport layer 170, the electron block layer 180, the yellow light emitting layer 190, the second electron transport layer 200 and the electron injection layer 210 on the charge generation layer 160, including Two stacks ST2 are located. The second hole transport layer 170 and the second electron transport layer 200 may have the same configuration as that of the first hole transport layer 130 and the first electron transport layer 150 of the first stack ST1, respectively. The electron block layer 180 includes a material of the hole transport layer and a metal or a metal compound to prevent electrons generated in the light emitting layer from passing to the hole transport layer. Accordingly, the LUMO level of the electron block layer is increased so that electrons cannot pass over.

The yellow light emitting layer 190 may be formed of a yellow green light emitting layer or a multilayer structure of a yellow green light emitting layer and a green light emitting layer. In this embodiment, a single-layer structure of a yellow light emitting layer emitting yellow green will be described as an example. The yellow light emitting layer 190 is CBP (4,4'-N,N'-dicarbazolebiphenyl) or Balq (Bis(2-methyl-8-quinlinolato-N1,O8)-(1,1'-Biphenyl-4-olato) aluminum) and may be made of a phosphorescent yellow-green dopant that emits yellow green to at least one host selected from among them.

The electron injection layer 210 serves to facilitate electron injection, and Alq ₃ (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, or SAlq may be used, but is not limited thereto. . The electron injection layer 210 may have a thickness of 1 to 50 nm. Here, if the thickness of the electron injection layer 210 is 1 nm or more, there is an advantage in that the electron injection characteristics can be prevented from being deteriorated, and if it is 50 nm or less, the thickness of the electron injection layer 210 is too thick to prevent electron movement. There is an advantage in that it is possible to prevent the driving voltage from being increased in order to improve it. Accordingly, the second hole transport layer 170 , the electron block layer 180 , the yellow light emitting layer 190 , the second electron transport layer 200 and the electron injection layer 210 on the charge generation layer 160 . A stack ST2 is constituted.

The cathode 220 is positioned on the second stack ST2 . The cathode 220 is an electron injection electrode, and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof having a low work function. Here, the cathode 220 may be formed to be thin enough to transmit light when the organic light emitting device has a front or double-sided light emitting structure, and when the organic light emitting device has a rear light emitting structure, it can reflect light. It can be formed as thick as possible.

As described above, the present invention provides an energy level between the P-type charge generation layer and the N-type charge generation layer by using the N-type charge generation layer as a pyrene compound while the charge generation layer is positioned between the first stack and the second stack. There are advantages to reducing the difference.

Hereinafter, the synthesis examples of the pyrene compound used in the N-type charge generation layer of the present invention and the organic electroluminescent device including the compound will be described in detail in the following Synthesis Examples and Examples. However, the examples disclosed below are only examples of the present invention, and the present invention is not limited to the following examples.

Synthesis example

1) Synthesis of 2-(4'-bromobiphenyl-4-yl)-1,10-phenanthroline (2-(4'-bromobiphenyl-4-yl)-1,10-phenanthroline)

2-Bromo-1,10-phenanthroline (10g, 39mmol) and 4'-bromo-4-biphenylboronic acid (11.8g, 42mmol) were added to 100mL of anhydrous tetrahydrofuran and stirred. Tetrakis(triphenylphosphine)palladium (2.4g, 2mmol), potassium carbonate (K2CO3, 12g, 85mmol), and 50mL of distilled water were added and refluxed at 80°C for 24 hours. When the reaction is complete, the reaction solution is cooled, the water layer is removed, and tetrahydrofuran is concentrated under reduced pressure to remove solid content. The solid was separated by column and recrystallized using dichloromethane and methanol to 2-(4'-bromobiphenyl-4-yl)-1,10-phenanthroline (2-(4'-bromobiphenyl-4-yl) -1,10-phenanthroline) (10.8 g, 26 mmol, 62%) was obtained.

2) Preparation of compound NC-35

To the synthesized 2-(4'-bromobiphenyl-4-yl)-1,10-phenanthroline (10.8 g, 26 mmol), pyrene-1-boronic acid (7.2 g, 29 mmol) was added to anhydrous tetrahydrofuran Add 100mL and stir. Tetrakis (triphenylphosphine) palladium (1.3 g, 1.2 mmol), potassium carbonate (K ₂ CO ₃ , 8 g, 58 mmol), and 50 mL of distilled water were added and refluxed at 80° C. for 24 hours. After the reaction is completed, the reaction solution is cooled, tetrahydrofuran is concentrated under reduced pressure to remove, and the generated solid is filtered. The resulting solid was purified by column and recrystallized using dichloromethane and methanol to obtain NC35 (9.1 g, 1.7 mmol, 59%).

Example

Hereinafter, an embodiment in which an organic electroluminescent device is fabricated using the above-described pyrene compound as an N-type charge generating layer is disclosed.

Example 1

After patterning so that the light emitting area of the ITO glass has a size of 2 mm × 2 mm, it was washed. After mounting the substrate in a vacuum chamber, the base pressure was set to 1×10 ^-6 torr, and HAT-CN was deposited as a hole injection layer on the anode ITO to a thickness of 50 Å, followed by the hole transport layer NPD (4,4'- Formed by depositing bis[N-(1-naphthyl)-N-phenylamino]-biphenyl) to a thickness of 1200 Å, and as a blue fluorescent light emitting layer, 250 Å of an anthracene-based material as a host and a pyrene-based material as a dopant have a doping concentration of 5% was formed with Then, as an electron transport layer, a heteroaryl-based material is formed to a thickness of 200 Å to form a first stack, and an alkali metal lithium is doped into a pyrene compound represented by NC-20 as an N-type charge generation layer to a thickness of 100 Å. was formed into a film, and a heteroaryl-based material was formed to a thickness of 200 Å as a P-type charge generating layer. An arylamine-based material was formed to a thickness of 200 Å as a hole transport layer, and a carbazole-based material was formed to a thickness of 200 Å as an electron blocking layer. Next, an Iridium compound as a dopant was formed at a dopant concentration of 20% on a heteroaryl-based host 150 Å as a phosphorescent yellow light emitting layer. On it, a heteroaryl-based material was formed to a thickness of 200 Å as an electron transport layer, LiF was formed to a thickness of 10 Å as an electron injection layer to form a second stack, and Al was formed to a thickness of 2000 Å as a cathode. An electroluminescent device was fabricated.

Example 2

An organic electroluminescent device was manufactured under the same conditions as in Example 1, except that a pyrene compound represented by NC-26 was used as a material of the N-type charge generation layer.

Example 3

An organic electroluminescent device was manufactured under the same conditions as in Example 1, except that a pyrene compound represented by NC-35 was used as a material of the N-type charge generation layer.

comparative example

An organic electroluminescent device was manufactured under the same conditions as in Example 1, except that the Bphen compound was used as a material for the N-type charge generation layer.

The driving voltage, current efficiency and color coordinates of the organic light emitting diodes manufactured according to Examples 1 to 3 and Comparative Examples were measured and shown in Table 1 below. In addition, the current density according to the driving voltage was measured and shown in FIG. 2 , the decrease rate of the luminance with time was measured and shown in FIG. 3 , and the emission spectrum was measured and shown in FIG. 4 .

Driving voltage (V)
current efficiency
(Cd/A) color coordinates CIE_x CIE_y comparative example 8.9 86.5 0.324 0.338 Example 1 8.4 87.2 0.329 0.341 Example 2 8.4 88.6 0.330 0.339 Example 3 8.5 86.7 0.327 0.335

As shown in Table 1, the organic electroluminescent devices manufactured according to Examples 1 to 3 of the present invention exhibited superior color coordinates than Comparative Examples, reduced driving voltage, and improved current efficiency. In particular, referring to FIG. 2 , the current density according to the driving voltage is improved in the embodiments of the present invention compared to the comparative example, and referring to FIG. 3 , the lifespan characteristics are remarkably increased. Referring to FIG. 4 , the luminescence intensity is also It was found to be increased compared to the comparative example.

Accordingly, the pyrene compound according to an embodiment of the present invention and the organic electroluminescent device including the same have advantages in that the driving voltage, current efficiency, color coordinates and lifespan characteristics can be improved, compared to the conventional organic electroluminescent device.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention can be changed to other specific forms by those skilled in the art to which the present invention pertains without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. In addition, the scope of the present invention is indicated by the claims to be described later rather than the above detailed description. In addition, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

100: organic electroluminescent device 110: anode
120: hole injection layer 130: first hole transport layer
140: blue light emitting layer 150: first electron transport layer
160: charge generation layer 160N: N-type charge generation layer
160P: P-type charge generation layer 170: second hole transport layer
180: electron block layer 190: yellow light emitting layer
200: second electron transport layer 210: electron injection layer
220: cathode

Claims (6)

An organic electroluminescent device formed between an anode and a cathode and including a first stack including a blue light emitting layer, a second stack including a yellow light emitting layer, and a charge generation layer positioned between the first stack and the second stack In
The first stack includes an electron transport layer between the blue light emitting layer and the charge generation layer, and the second stack includes an electron transport layer and an electron injection layer between the yellow light emitting layer and the cathode,
The charge generation layer includes an N-type charge generation layer and a P-type charge generation layer, The N-type charge generation layer is an organic electroluminescent device, characterized in that it comprises a pyrene compound represented by the following formula (1) or (2).
[Formula 1]

[Formula 2]

In Formulas 1 and 2,
n is 1 or 2, R ₁ is a phenanthroline group, and in Formula 2, R ₂ is any one selected from the group consisting of substituted or unsubstituted alkyl, aromatic compounds, heteroaromatic compounds, arylamines and heteroarylamines ego,
when n is 1, X is pyridinylene;
When n is 2, X is an aromatic compound or heteroaromatic compound containing at least one of C and N, and the substituent is bonded to the 1st and 6th positions of the pyrene.
According to claim 1,
The pyrene compound is an organic electroluminescent device, characterized in that any one selected from the compounds shown below.

delete delete According to claim 1,
The first stack may further include a hole injection layer and a hole transport layer between the anode and the blue light emitting layer.
According to claim 1,
The second stack is an organic electroluminescent device, characterized in that it further comprises a hole transport layer between the charge generation layer and the yellow light emitting layer.

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