KR102134704B1 - Blue phosphorescence composition and organic light emitting diode comprising the same - Google Patents

Abstract

,

,

및

중 선택된 어느 하나이고, 상기 C₁ 및 C₂는 각각 독립적으로 안트라센, 페난트렌 및 파이렌 중 선택된 어느 하나이며, 상기 S₁ 및 S₂는 각각 독립적으로 방향족 화합물 또는 헤테로고리 화합물로 이루어진다.The blue fluorescent compound according to an embodiment of the present invention is characterized by being represented by the following formula (1).
[Formula 1]
S ₁ -C ₁ -LC ₂ -S ₂
In Chemical Formula 1,
L is

,

,

And

C ₁ and C ₂ are each independently selected one of anthracene, phenanthrene and pyrene, and S ₁ and S ₂ are each independently composed of an aromatic compound or a heterocyclic compound.

Description

Blue fluorescent compound and organic light emitting device including the same{BLUE PHOSPHORESCENCE COMPOSITION AND ORGANIC LIGHT EMITTING DIODE COMPRISING THE SAME}

The present invention relates to an organic electroluminescent device, and more particularly to a novel blue fluorescent compound and an organic electroluminescent device comprising the same.

Recently, the importance of a display device (FPD: Flat Panel Display) has increased with the development of multimedia. In response, Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), Organic Light Emitting Diode Display Device, etc. Many of the same displays have been put to practical use.

Among them, the organic light emitting device is a self-luminous device that emits light while extinguishing after pairing electrons and holes when a charge is injected into an organic light emitting layer formed between a cathode, an electron injection electrode, and an anode, a hole injection electrode.

Not only can the organic light emitting device form a device on a flexible substrate such as plastic, but it can be driven at a voltage lower than 10V, compared to a plasma display panel or an inorganic electroluminescent display, it consumes less power and has excellent color sense. There are advantages. In addition, the organic light emitting device can represent three colors of red, green, and blue, and is a target of interest of many people as a next-generation display device expressing rich colors.

The organic light emitting device may be formed by sequentially stacking an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode. In the light emitting layer, electrons and holes are combined to form excitons, and the excitons excited to fall to the ground state and emit light. The organic electroluminescent device has an external quantum efficiency and an internal quantum efficiency, and the external quantum efficiency (η _ext ) can be expressed by the following equation.

η _ext = η _int × Г × Φ × η _out-coupling

(Where η _int is the internal quantum efficiency, Г is the charge balance factor, Φ is the radiative quantum efficiency, and η _out-coupling is the out coupling efficiency). )

In the above equation, the recombination index means the balance of holes and electrons when excitons are formed, and generally has a value of '1' assuming 1:1 matching of 100%. Since the radiative quantum efficiency is a value related to the luminous efficiency of the actual luminous body, it relies on the photoluminescence of the dopant in the host-dopant system. The external binding efficiency is a value of how efficiently the light of the luminescent molecule can be extracted. Generally, when an isotropic molecule is deposited through thermal evaporation to form a thin film, individual luminescent molecules do not have a certain directionality and exist in a disordered state. The external coupling efficiency in this irregularly oriented state is generally assumed to be 0.2. The internal quantum efficiency generally has a limit value of up to 0.25 in the case of fluorescence. In theory, when holes and electrons meet to form excitons, singlet excitons and triplet excitons are generated in a ratio of 1:3, and only singlet excitons participate in fluorescence, and the remaining 75% of triplet excitons are used for fluorescence. Because you can not participate.

Combining the above four elements, the maximum element efficiency of the final fluorescent organic electroluminescent element is only 5% or less. In particular, in the case of the proposed phosphorescence as an alternative to the limited fluorescence efficiency, the development of a high-efficiency fluorescent material is required with the development of the blue light-emitting material very insufficient.

The present invention provides a high-efficiency organic electroluminescent device by providing a novel blue fluorescent compound.

In order to achieve the above object, the blue fluorescent compound according to an embodiment of the present invention is characterized in that represented by the following formula (1).

[Formula 1]

S ₁ -C ₁ -LC ₂ -S ₂

In Chemical Formula 1,

,

,

및

중 선택된 어느 하나이고, 상기 C₁ 및 C₂는 각각 독립적으로 안트라센, 페난트렌 및 파이렌 중 선택된 어느 하나이며, 상기 S₁ 및 S₂는 각각 독립적으로 방향족 화합물 또는 헤테로고리 화합물로 이루어진다.L is

,

,

And

C ₁ and C ₂ are each independently selected one of anthracene, phenanthrene and pyrene, and S ₁ and S ₂ are each independently composed of an aromatic compound or a heterocyclic compound.

,

,

및

중 선택된 어느 하나인 것을 특징으로 한다.The aromatic compound

,

,

And

It is characterized in that any one selected from.

The heterocyclic compound is characterized by comprising S or O.

또는

로 이루어진 것을 특징으로 한다.The heterocyclic compound

or

It is characterized by consisting of.

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

In addition, the organic light emitting device according to an embodiment of the present invention is characterized in that in the organic light emitting device including an organic film formed between the anode and the cathode, the organic film includes the blue fluorescent compound.

It is characterized in that the organic film is a light emitting layer.

It is characterized in that the blue fluorescent compound is used as a host for the light emitting layer.

It characterized in that it further comprises any one or more selected from the hole injection layer, the hole transport layer, the electron transport layer and the electron injection layer between the anode and the cathode.

The blue fluorescent compound and the organic light emitting device including the same according to an embodiment of the present invention have the advantage of reducing the driving voltage of the device and improving current efficiency, power efficiency and life.

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

Referring to FIG. 1, the organic light emitting device 100 according to an embodiment of the present invention includes an anode 110, a hole injection layer 120, a hole transport layer 130, a light emitting layer 140, and an electron transport layer 150 , An electron injection layer 160 and a cathode 170.

The anode 110 is an electrode for injecting holes and may be any one of indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO). In addition, when the anode 110 is a reflective electrode, the anode 110 has a reflective layer made of any one of aluminum (Al), silver (Ag), or nickel (Ni) under a layer made of any one of ITO, IZO, or ZnO. It may further include.

The hole injection layer 120 may serve to facilitate the injection of holes from the anode 110 to the light emitting layer 140, cupper phthalocyanine (CuPc), poly(3,4)-ethylenedioxythiophene (PEDOT), PANI (polyaniline) and NPD (N,N-dinaphthyl-N,N'-diphenyl benzidine).

The hole injection layer 120 may have a thickness of 1 to 150 nm. Here, when the thickness of the hole injection layer 120 is 1 nm or more, there is an advantage of preventing the hole injection characteristics from being deteriorated. If it is 150 nm or less, the hole injection layer 120 is too thick to move holes. In order to improve, there is an advantage that can prevent the driving voltage from rising.

The hole transport layer 130 serves to facilitate the transport of holes, 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) It may be made of any one or more, but is not limited thereto.

The hole transport layer 130 may have a thickness of 1 to 150 nm. Here, when the thickness of the hole transport layer 130 is 5 nm or more, there is an advantage of preventing the hole transport properties from being deteriorated, and when 150 nm or less, the thickness of the hole transport layer 130 is too thick to improve the movement of holes In order to prevent the driving voltage from rising, there is an advantage.

The light emitting layer 140 may be made of a material that emits blue light, and may be formed using a fluorescent material. In this embodiment, a material emitting blue light will be described.

The light emitting layer 140 of the present invention may be made of a blue fluorescent compound represented by the following Chemical Formula 1.

[Formula 1]

S ₁ -C ₁ -LC ₂ -S ₂

,

,

및

중 선택된 어느 하나이고, 상기 C₁ 및 C₂는 각각 독립적으로 안트라센, 페난트렌 및 파이렌 중 선택된 어느 하나이며, 상기 S₁ 및 S₂는 각각 독립적으로 방향족 화합물 또는 헤테로고리 화합물로 이루어진다.In Chemical Formula 1, L is

,

,

And

C ₁ and C ₂ are each independently selected one of anthracene, phenanthrene and pyrene, and S ₁ and S ₂ are each independently composed of an aromatic compound or a heterocyclic compound.

,

,

및

중 선택된 어느 하나로 이루어진다. 또한, 상기 헤테로고리 화합물은 S 또는 O를 포함하는 물질일 수 있으며, 구체적으로 헤테로고리 화합물은

또는

로 이루어진다.Here, the aromatic compound

,

,

And

It is made of any one selected. In addition, the heterocyclic compound may be a material containing S or O, specifically the heterocyclic compound

or

Is made of

Therefore, the blue fluorescent compound of the present invention is made of any one of the compounds shown below.

The blue fluorescent compound of the present invention described above introduces triplet-triplet annihilation (TTA) substances, anthracene, phenanthrene, or pyrene, into the core, thereby fluorescing triplet excitons. Participation in the conventional quantum efficiency limit of 0.25 can be exceeded. In addition, these cores are synthesized in a dual core form to increase the molecular weight to secure thermal stability. In addition, by designing molecules in a two-dimensional planar and anisotropic form, the molecules are aligned in a horizontal direction to the substrate and the external bonding efficiency is improved.

The blue fluorescent compound of the present invention described above is used as a host among the host and the dopant of the light emitting layer 140.

The electron transport layer 150 serves to facilitate the transport of electrons, and is made of any one or more selected from the group consisting of Alq3 (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. However, it is not limited thereto. The electron transport layer 150 may have a thickness of 1 to 50 nm. Here, when the thickness of the electron transport layer 150 is 1 nm or more, there is an advantage of preventing the electron transport properties from being deteriorated, and when it is 50 nm or less, the thickness of the electron transport layer 150 is too thick to improve electron movement. In order to prevent the driving voltage from rising, there is an advantage.

The electron injection layer 160 serves to facilitate the injection of electrons, and may use, but is not limited to, Alq3 (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq. The electron injection layer 160 may have a thickness of 1 to 50 nm. Here, when the thickness of the electron injection layer 160 is 1 nm or more, there is an advantage of preventing the electron injection characteristics from deteriorating, and when it is 50 nm or less, the thickness of the electron injection layer 150 is too thick to move electrons. In order to improve, there is an advantage that can prevent the driving voltage from rising.

The cathode 170 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 anode 170 may be formed to have a thickness that is thin enough to transmit light when the organic light emitting device is a front or both sides light emitting structure, and reflect light when the organic light emitting device is a back light emitting structure. It can be formed to be thick enough.

Hereinafter, a synthesis example of the blue fluorescent compound of the present invention and an organic electroluminescent device comprising the compound will be described in detail in the following synthesis examples and examples. However, the following examples are only illustrative of the present invention, and the present invention is not limited to the following examples.

Synthetic example

1) Preparation of compound E

Compound A (29mmol) was added to a round-bottom flask, and 1,4-dioxane (1,4-dioxane) was added and stirred at room temperature. When compound A is completely dissolved in 1,4-dioxane, compound D (62 mmol) is added, stirred for 3 hours, and then the reaction is quenched using ice water and hydrochloric acid (HCl). After extraction, washed with hexane, and then filtered to obtain 8.0 g of compound E.

2) Preparation of compound F

Compound B (20 mmol), compound C (22 mmol), tetrakis (triphenylphosphine) palladium (0.5 mmol) and potassium carbonate (12 g) toluene in a two-necked round bottom flask (Toluene) (30ml), dissolved in water (H ₂ O) (10ml), and stirred for 24 hours in a bath of 100 ℃. After the reaction is completed, toluene is removed, followed by extraction with ethyl ether and water, followed by distillation under reduced pressure to perform a silica gel column. Thereafter, the solvent was distilled under reduced pressure, and then recrystallized using dichloromethane and petroleum ether to filter to obtain 6.0 g of Compound F solid.

3) Preparation of compound G

Compound F (19mmol) and chloroform (30ml) were added to the round-bottom flask, stirred, and bromine (23 mmol) was slowly added. After stirring for 3 hours, the reaction was quenched with sodium thiosulfate dissolved in deionized water and 6.5 g of powder G was obtained using dichloromethane and methanol.

4) Preparation of compound H

Compound G (13mmol) was added to a nitrogen-circulated round-bottom flask and dissolved in tetrahydrofuran (THF). When compound G is completely dissolved in tetrahydrofuran, a dry ice bath is used to create a temperature environment of -80 °C. Slowly add Bu-Li at -80°C and stir for 4 hours, then slowly add borolane (15 mmol). After stirring Overnight, raise the temperature to room temperature and stir for 2 hours. After stirring, hydrochloric acid and water were added, stirred for 1 hour, extracted, washed with hexane, and filtered to obtain 3.0 g of Compound H as a solid.

5) Preparation of compound AT-1

After dissolving Compound E (3mmol), Compound H (4mmol), tetrakis(triphenylphosphine)palladium (0.5mmol) and potassium carbonate (12g) in a round-bottom flask in toluene (30ml) and water (10ml) , It was stirred for 24 hours in a bath of 100 ℃. After the reaction was completed, toluene was removed, followed by extraction with ethyl ether and water, followed by distillation under reduced pressure to perform a silica gel column. After distilling off the solvent under reduced pressure, the mixture was recrystallized using dichloromethane and petroleum ether, and filtered to obtain 2.0 g of a solid compound AT-1.

Hereinafter, an embodiment in which an organic electroluminescent device is manufactured using the blue fluorescent compound of the present invention represented by AT-1 prepared in the above-mentioned Synthesis Example as a host of a blue light emitting layer will be described.

Example

The ITO glass was patterned to have a light emitting area of 3 mm x 3 mm, and then washed. After the substrate was mounted in the vacuum chamber, the basic pressure was 1×10 ^-6 torr, and then DNTPD was deposited as a hole injection layer on the anode ITO to a thickness of 700 MPa, and the hole transport layer was formed to form NPD to a thickness of 300 MPa, As a light emitting layer, the compound AT-1 250Å as a host and DPAVBi as a dopant were deposited at a doping concentration of 4%. Alq ₃ was formed to a thickness of 350 으로 as an electron transport layer, LiF was formed to a thickness of 5 으로 as an electron injection layer, and Al was formed as a thickness of 1000 Å as a cathode to produce an organic electroluminescent device.

AT-1

_

Comparative example

An organic electroluminescent device was manufactured under the same process conditions as the above-described embodiment, except that AND was used as the host.

The driving voltage, driving current, luminance, current efficiency, power efficiency, color coordinates and lifetime of the organic light emitting device manufactured according to the above-described examples and comparative examples are measured and are shown in Table 1 below.

Driving voltage (V) Driving current (mA) Luminance (cd/㎡) Current efficiency (cd/A) Power efficiency (lm/W) Color coordinate Life (h)
CIE_x CIE_y Comparative example 5.4 0.9 724 7.2 4.2 0.144 0.205 650 Example 4.3 0.9 725 8.9 6.5 0.142 0.203 1080

Referring to Table 1, the organic light emitting device manufactured according to the embodiment of the present invention exhibits driving current, luminance, and color coordinates at the same level as the comparative example, while driving voltage is reduced, and current efficiency, power efficiency, and lifetime This was significantly improved.

Therefore, the blue fluorescent compound and the organic light emitting device including the same according to an embodiment of the present invention have the advantage of reducing the driving voltage of the device and improving the current efficiency, power efficiency and life.

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

100: organic electroluminescent element 110: anode
120: hole injection layer 130: hole transport layer
140: light emitting layer 150: electron transport layer
160: electron injection layer 170: cathode

Claims (9)

Blue fluorescent compound, characterized in that represented by the formula (1).
[Formula 1]
S ₁ -C ₁ -LC ₂ -S ₂
In Chemical Formula 1,
L is

ego,
C ₁ and C ₂ are each independently selected from anthracene, phenanthrene, and pyrene,
The S ₁ and S ₂ are each independently composed of an aromatic compound or a heterocyclic compound. According to claim 1,
The aromatic compound

,

,

And

Blue fluorescent compound, characterized in that any one selected from.
According to claim 1,
The heterocyclic compound is a blue fluorescent compound comprising S or O.
According to claim 3,
The heterocyclic compound

or

Blue fluorescent compound, characterized in that consisting of.
According to claim 1,
The blue fluorescent compound is a blue fluorescent compound, characterized in that any one selected from the following compounds.

In the organic electroluminescent device comprising an organic film formed between the anode and the cathode,
An organic electroluminescent device, characterized in that the organic film comprises the blue fluorescent compound of any one of claims 1 to 5.
The method of claim 6,
An organic electroluminescent device characterized in that the organic film is a light emitting layer.
The method of claim 7,
An organic electroluminescent device characterized in that the blue fluorescent compound is used as a host for the light emitting layer.
The method of claim 6,
An organic electroluminescent device further comprising any one or more selected from a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer between the anode and the cathode.

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