KR100581640B1 - Organic Electroluminescent Device - Google Patents

Abstract

The present invention discloses an organic electroluminescent device of a type having an emission band and comprising an organic layer provided between an anode and a cathode, wherein the organic layer comprises a distyryl compound represented by the following formula (1).

Where

At least one of R ¹ , R ² , R ³ and R ⁴ represents an aryl group represented by the following formula (2),

R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represent a hydrogen atom, a cyano group, a nitro group or a halogen atom.

Wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ may be the same or different and each is a saturated or unsaturated alkylamino group.

Organic electroluminescent device, anode, cathode, distyryl compound, luminance, voltage, hole transport layer, electron transport layer, light emitting layer

Description

Organic Electroluminescent Device

1 is a schematic cross-sectional view of an essential part of an organic electroluminescent device according to the present invention.

2 is a schematic cross-sectional view of a major part of another type of organic electroluminescent device according to the invention.

3 is a schematic cross-sectional view of an essential part of another type of organic electroluminescent device according to the invention.

4 is a schematic cross-sectional view of an essential part of another type of organic electroluminescent device according to the invention.

5 is a layout view of a full color flat panel display using the organic electroluminescent device according to the present invention;

6 is an emission spectrum diagram of the organic electroluminescent device of Example 1 according to the present invention;

7 is an emission spectrum diagram of the organic electroluminescent device of Example 2 according to the present invention;

8 is a graph showing the voltage-luminance characteristics of the organic electroluminescent device of Example 1 according to the present invention.

9 is a graph showing the voltage-luminance characteristics of the organic electroluminescent device of Example 2 according to the present invention.

<Explanation of symbols for the main parts of the drawings>

(1): substrate (2): transparent electrode (anode)

(3): cathode (4): protective (sealing) layer

(5), (5a), (5b): organic layer (6), (10): hole transport layer

(7), (12): electron transport layer 8; power

(11): light emitting layer 14: luminance signal circuit

(15) control circuit 20: emitting light

A, B, C, D: organic electroluminescent device

The present invention relates to an organic electroluminescent device (organic EL device) in which an organic layer having an emission band is provided between an anode and a cathode.

For example, research and development are being extensively conducted on high-efficiency, lightweight flat panel displays for computer and television image displays.

CRTs are the most widely used for displays because of their high brightness and excellent color reproducibility. However, pipes are problematic in that they are bulky, heavy, and have high power consumption.

As high-efficiency, lightweight flat panel displays, liquid crystal displays such as active matrix driving type are commercially available. However, since liquid crystal displays have a narrow viewing angle and do not rely on self-luminescence, they require a lot of power consumption for backlight when placed in a dark environment, and the response to high-speed video signals with high precision expected to be practical in the future is difficult. It has a problem that is not satisfactory. In particular, it is difficult to manufacture a liquid crystal display having a large screen size, and there is a problem due to high manufacturing cost.

As a substitute for this, a type of display using a light emitting diode may be possible, but such a display is also expensive to manufacture and has another problem that it is difficult to form a matrix structure of the light emitting diode on a substrate. Thus, when considered as a low cost display alternative to CRTs, this type of display suffers from many problems that must be addressed prior to actual use.

As a flat panel display that can solve these problems, attention has recently been focused on organic electroluminescent devices (organic EL devices) using organic light emitting materials. More specifically, it is expected that by using an organic compound as the light emitting material, it is possible to realize a flat panel display using self-luminous, having a high reaction rate and independent of the viewing angle.

The organic electroluminescent device has a structure for forming an organic thin film containing a light emitting material capable of emitting light through charge of a current between an optically transparent anode and a metallic cathode. The research report (Applied Physics Letters, Vol. 51, No. 12, pages 913-915 (1987), C. Tang and SA VanSlyke) contains organic thin films. A device structure having a two-layer structure comprising a thin film composed of a hole transporting material and a thin film composed of an electron transporting material, and emitting light by recombination of holes and electrons injected from each electrode into an organic film (single heterogeneous) An organic EL device having a structure) is disclosed.

In this element, a hole transport material or an electron transport material also acts as a light emitting material. Light emission occurs in a wavelength band corresponding to the energy difference between the ground state and the energized state of the luminescent material. By using such a two-layer structure, the driving voltage can be greatly reduced while improving the luminous efficiency.

Later, published in a research report (Japanese Journal of Applied Physics, Vol. 27, No. 2, L269-L271 pages (1988), C. Adachi, S. Tokita, T. A three-layer structure (organic EL device having a double heterostructure) of hole transport material, light emitting material and electron transport material as disclosed in T. Tsutsui and S. Saito has been developed. In addition, published in a research report (Journal of Applied Physics, Vol. 65, No. 9, 3610-3616 pages (1989), C. W. Tang, S. A. Van Sliche and C. H. Chen A device structure has been developed that includes a luminescent material present in an electron transport material as disclosed in &lt; RTI ID = 0.0 &gt; These studies have demonstrated high luminance luminescence at low voltage, resulting in extensive research and development in recent years.

The organic compound used as the light emitting material is advantageous because of the variety of kinds, which can theoretically change the emission color by changing the molecular structure. Therefore, compared to thin film EL devices using inorganic materials, it may be easier to provide three colors of R (red), G (green) and B (blue) as appropriate molecular designs, which have excellent color purity essential for full-color display. have.

However, organic electroluminescent devices still have problems to be solved. More specifically, there is a difficulty in developing a stable red light emitting device having high brightness. Tris (8-quinolinol) aluminum (hereinafter referred to as Alq ₃ ) used as the currently reported electron transport material in DCM [4-dicyanomethylene-6- (p-dimethylaminostyryl) -2-methyl-4H In the case of red light emission obtained by doping -pyran, this electron transporting material is not satisfactory as a display material in terms of maximum brightness and reliability.

tea. Tsutsui and D. U. BSB-BCN, as reported by D. U. Kim (Inorganic and Organic Electroluminescence Conference (Berlin 1996)), can achieve high brightness of more than 1000 cd / m 2, but is not always perfect as red for full-color displays.

Therefore, there is a demand for a red light emitting element having high luminance, stability, and high color purity.

In Japanese Laid-open Patent Application Hei 7-188649 (Japanese Patent Application Hei 6-148798), it has been proposed to use a specific type of distyryl compound as an organic electroluminescent material. However, the intended emission color was blue rather than red.

Therefore, there is a need for an organic electroluminescent element that ensures high luminance and stable red light emission.

Intensive investigation has been made to solve the above problems, and as a result, when using a specific type of distyryl compound as a light emitting material, a reliable red light emitting device which is very useful for realizing a high brightness stable full color display can be provided. It has been found that this has led to the completion of the present invention.

Accordingly, an object of the present invention includes an anode and a cathode, an organic layer having an emission band is disposed between the anode and the cathode, the organic layer is an organic electric field comprising an organic light emitting material comprising a distyryl compound of formula (1) It is to provide a light emitting device.

<Formula 1>

Where

At least one of R ¹ , R ² , R ³ and R ⁴ is an aryl group represented by the following formula (2),

The remaining (s) of R ¹ , R ² , R ³ and R ⁴ are unsubstituted phenyl groups,

R ⁵ , R ⁶ , R ⁷ and R ⁸ are selected from the group consisting of hydrogen atom, cyano group, nitro group and halogen atom.

<Formula 2>

Where

R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are saturated or unsaturated alkylamino groups.

Another object of the present invention comprises an anode and a cathode, an organic layer having an emission band is disposed between the anode and the cathode, the organic layer is one or more represented by a formula selected from the group consisting of the following formulas 3a to 3e An organic electroluminescent device comprising an organic light emitting material containing a distyryl compound is provided.

More specifically, the present invention relates to an organic electroluminescent device of the type comprising an organic layer having an emission band and provided between an anode and a cathode, and which contains, as an essential component, an organic material capable of generating light emission by charging an electric current. As an organic light emitting material, the organic layer contains a distyryl compound represented by the following Formula (1).

<Formula 1>

Where

At least one of R ¹ , R ² , R ³ and R ⁴ represents an aryl group represented by the following formula (2),

The remaining (s) represent an unsubstituted phenyl group,

R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and represent a hydrogen atom, a cyano group, a nitro group or a halogen atom (including F, Cl, Br or I), respectively.

<Formula 2>

Where

R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ may be the same or different and each may be saturated or unsaturated alkylamino group, preferably at least 2 carbon atoms, more preferably at 2 to 12 carbon atoms, or A group which may be one or more of those consisting of unsaturated dialkylamino groups.

By using the distyryl compound of the formula (1) as a light emitting material, it is possible not only to provide a device having excellent stability electrically, thermally or chemically, but also to obtain stable red light emission of high luminance.

The distyryl compound used for the organic electroluminescent element of this invention is described.

As the distyryl compound represented by Chemical Formula 1 and used as a light emitting material in the organic electroluminescent device of the present invention, for example, one or more of molecular structures of the following Chemical Formulas 3a, 3b, 3c, 3d or 3e may be used.

<Formula 3a>

<Formula 3b>

<Formula 3c>

<Formula 3d>

<Formula 3e>

Other objects and advantages of the present invention will become apparent upon reading the following detailed description and the appended claims, and with reference to the drawings.

It is to be understood that the drawings do not need to be drawn to scale, and that embodiments are often illustrated by graphical symbols, dotted lines, diagram symbols, and fragment drawings. In certain instances, details may be omitted that are not necessary to understand the invention or that may make it difficult to understand other details. It should be understood, of course, that the present invention need not be limited to the particular embodiments illustrated herein.

1 to 4 show examples of organic electroluminescent devices according to the present invention, respectively.

FIG. 1 shows a transmissive organic electroluminescent element A in which luminescent light 20 passes through a cathode 3 and can be observed from the side of the protective layer 4. 2 shows a reflective organic electroluminescent element B in which the light reflected from the cathode 3 can also be obtained as the luminescent light 20.

In the figure, reference numeral 1 denotes a substrate for forming an organic electroluminescent element, which can be made of glass, plastic and other suitable materials. When using organic electroluminescent devices in combination with other types of display devices, the substrate can be shared. Reference numeral 2 denotes a transparent electrode (anode), and ITO (indium tin oxide), SnO ₂ , or the like can be used.

Reference numeral (5) represents an organic light emitting layer and contains the above-described distyryl compound as a light emitting material. For the layer arrangement for obtaining the luminescent light 20, the luminescent layer may have various types of layer arrangements known so far. As described later, if the material for the hole transport layer or the electron transport layer has a luminescent property, for example, a laminated structure of these thin films can be used. Further, in order to increase charge transportability within the scope of meeting the object of the present invention, one or both of the hole transport layer and the electron transport layer may have a laminated structure of a thin film made of different types of materials, or different types of materials Thin films consisting of mixtures of can be used without limitation. In addition, in order to improve the luminescence properties, one or more fluorescent materials may be used to provide a structure in which a thin film of fluorescent material is interposed between the hole transport layer and the electron transport layer. Alternatively, a structure in which at least one fluorescent material is present in one or both of the hole transport layer or the electron transport layer can be used. In this case, a thin film for controlling hole or electron transport can be introduced into the layer configuration in order to improve the fluorescence efficiency.

The distyryl compound represented by Formula 3 has both hole transporting properties and electron transporting properties, and may be used as a light emitting layer serving as an electron transporting layer in an element arrangement or as a light emitting layer serving as a hole transporting layer. It is also possible to provide an arrangement in which the distyryl compound is formed as a light emitting layer interposed between the electron transport layer and the hole transport layer.

It can be seen from FIGS. 1 and 2 that the symbol (3) represents the cathode, and the electrode material can be made of an alloy of an active metal such as Li, Mg, Ca, etc. and a metal such as Ag, Al, In, or these metals. The laminated structure of the thin film can be used. In the transmissive organic electroluminescent device, the optical transmittance required for the intended use can be obtained by controlling the thickness of the cathode. Reference numeral 4 in the drawing denotes a sealing / protective layer, and its effect increases when the entire organic electroluminescent element is covered with the sealing / protective layer. Any suitable material that ensures airtightness can be used as the sealing / protective layer. Reference numeral 8 denotes a drive power supply for current charging.

In the organic electroluminescent device of the present invention, the organic layer may have an organic laminated structure (single heterostructure) in which a hole transporting layer and an electron transporting layer are stacked, and a material for forming the hole transporting layer or the electron transporting layer is composed of the distyryl compound. Alternatively, the organic layer may have an organic stacked structure (double heterostructure) in which a hole transporting layer, a light emitting layer, and an electron transporting layer are sequentially stacked, and the light emitting layer is formed of the distyryl compound.

An example of an organic electroluminescent device having an organic laminated structure is shown. FIG. 3 is composed of a laminated structure in which an organic layer 5a composed of an optically transmissive anode 2, a hole transport layer 6 and an electron transport layer 7, and a cathode 3 are sequentially stacked on the optically transmissive substrate 1, An organic electroluminescent device C of a single heterostructure in which the laminated structure is sealed with the protective layer 4 is shown.

In the layer configuration as shown in FIG. 3 (omiting the light emitting layer), the emitted light 20 having a predetermined wavelength is emitted from the interface between the hole transporting layer 6 and the electron transporting layer 7 and the substrate 1 Is observed in terms of.

4 is a stack in which an organic layer 5b composed of an optically transmissive anode 2, a hole transport layer 10, a light emitting layer 11, and an electron transport layer 12 and a cathode 3 are sequentially stacked on an optically transmissive substrate 1. Structure, and the laminated structure shows an organic electroluminescent element D having a double heterostructure sealed with a protective layer 4.

In the organic electroluminescent device as shown in FIG. 4, when DC voltage is applied between the anode 2 and the cathode 3, holes injected from the anode 2 are transferred to the light emitting layer 11 through the hole transport layer 10. Electrons injected from the cathode 3 reach the light emitting layer 11 through the electron transport layer 12. As a result, the electrons / holes are recombined in the light emitting layer 11 to generate singlet excitons, thereby generating light having a predetermined wavelength generated from the singlet excitons.

In the aforementioned organic electroluminescent elements C and D, optically transmissive materials such as glass and plastic can be suitably used for the substrate 1. The substrate can be shared when the device is used in combination with other types of display devices, or when the stack structure shown in FIGS. 3 and 4 is arranged in the form of a matrix. Both devices C and D can have a transmissive or reflective structure.

The anode 2 is composed of a transmissive electrode in which ITO (indium tin oxide) or SnO ₂ or the like can be used. In order to improve the charge injection rate, a thin film made of an organic material or an organometallic compound may be provided between the anode 2 and the hole transport layer 6 (or the hole transport layer 10). It is to be understood that when the protective layer 4 is formed of a conductive material such as a metal, an insulating film may be provided on the side of the anode 2.

The organic layer 5a of the organic electroluminescent element C is composed of a laminated organic layer of the hole transporting layer 6 and the electron transporting layer 7, and the above-described distyryl compound is contained in one or both of these layers to emit light. Alternatively, the electron transport layer 7 can be provided. The organic layer 5b of the organic electroluminescent element D is composed of a hole transport layer 10, a light emitting layer 11 containing the above-described distyryl compound, and a laminated organic layer of the electron transport layer 12, and in the form of other various types of stacked structures. There may be. For example, one or both of the hole transport layer and the electron transport layer may have luminescence.

In particular, it is preferable that the hole transport layer 6 or the electron transport layer 7 and the light emitting layer 11 each consist of a layer made of the distyryl compound used in the present invention. These layers may be formed solely of the aforementioned distyryl compounds or may be formed through the co-deposition of the aforementioned distyryl compounds and other types of hole or electron transport materials (eg, aromatic amines or pyrazolines, etc.). . Further, in order to improve the hole transporting property of the hole transporting layer, a hole transporting layer composed of a plurality of hole transporting materials to be laminated may be formed.

In the organic electroluminescent element C, the light emitting layer may be the electron transporting light emitting layer 7, but light may be emitted from the hole transporting layer 6 or an interface thereof, depending on the voltage applied from the power source 8. Likewise, in the organic electroluminescent device D, the light emitting layer may be the electron transport layer 12 or the hole transport layer 10 in addition to the layer 11. In order to improve the light emission performance, it is desirable to provide a structure in which the light emitting layer 11 containing at least one fluorescent material is interposed between the hole transport layer and the electron transport layer. Alternatively, the fluorescent material may be contained in one or both of the hole transport layer or the electron transport layer. In such a case, in order to improve the luminous efficiency, a thin film (hole blocking layer or exciton generating layer) for controlling the transport of holes or electrons may be provided in the layer configuration.

The material used as the cathode 3 may be an alloy of an active metal such as Li, Mg, and Ca and a metal such as Ag, Al, In, or the like, or a laminated structure of these metal layers may be used. With the appropriate choice of cathode thickness and alloy type, it is possible to fabricate organic electroluminescent devices adapted for the application.

The protective layer 4 acts as a sealing film and is configured to cover the entire organic electroluminescent device, thereby improving the charge injection rate and the luminous efficiency. When the airtightness is ensured, a material containing a single metal or an alloy thereof, such as aluminum, gold or chromium, can be appropriately selected for this purpose.

The current applied to each of the organic electroluminescent elements disclosed above is typically direct current, but pulse current or AC current may also be used. The values of current and voltage are not important as long as they do not destroy the device. However, in consideration of the power consumption and lifespan of the organic electroluminescent device, it is desirable to generate light emission efficiently by using as little electric energy as possible.

Next, FIG. 5 shows a configuration of a flat panel display using the organic electroluminescent device of the present invention. As can be seen from the figure, for example, in the case of a full-color display, the organic layer 5 (5a, 5b) capable of emitting three primary colors of red (R), green (G) and blue (B) is the cathode 3 ) And the anode 2. The cathode 3 and the anode 2 can be provided in the form of a strip in which they cross each other, and a signal voltage selected by the luminance signal circuit 14 and the control circuit with a shift register 15 is applied, respectively. As a result, the organic layer at the position (pixel) where the selected cathode 3 and anode 2 intersect, emits light.

More specifically, FIG. 5 shows, for example, a hole 5 and a laminate 5 of at least one of a light emitting layer and an electron transporting layer provided between a cathode 3 and an anode 2 (see FIG. 3 or 4) 8 Shows a x 3 RGB simple matrix. The cathode and anode are patterned in strip form and cross each other in the matrix, where signal voltage is applied in time series from the control circuits 15 and 14 with shift registers, whereby electroluminescence or Causes luminescence. The EL element having such a configuration can be used not only as a display for character / signal but also as an image reproducing apparatus. Moreover, the stripped patterns of the anode 3 and the cathode 2 can be arranged for each color of red (R), green (G) and blue (B) to produce a solid color or full color solid flat panel display.

<Example>

The invention is described in more detail by way of example and should not be construed as limiting the invention.

<Example 1>

This example uses a compound of formula (3a), which is a distyryl compound of formula (1) in which R ² and R ³ each represent a 4-dimethylaminophenyl group, and R ⁶ and R ⁸ each represent a cyano group, as a hole transporting luminescent material. Illustrates the fabrication of an electroluminescent device having a single heterostructure.

<Formula 3a>

A 30 mm x 30 mm glass substrate, on which a 100 nm thick anode made of ITO was formed, was placed in a vacuum deposition apparatus. A metallic mask having a plurality of 2.0 mm by 2.0 mm unit openings was placed adjacent the substrate as a deposition mask. The compound of Formula 3a was subjected to vacuum deposition in a vacuum of 10 ⁻⁴ Pa or less to form, for example, a 50 nm thick hole transport layer (also acting as a light emitting layer). The deposition rate was 0.1 nm / second.

Also, the chemical formula

Alq ₃ (tris (8-quinolinol) aluminum) was provided as an electron transport material and deposited in contact with the hole transport layer. The electron transport layer made of Alq ₃ was, for example, adjusted to a thickness of 50 nm and the deposition rate was adjusted to 0.2 nm / second.

A laminated film of Mg and Ag used as the cathode material was used. Mg and Ag were respectively deposited at a deposition rate of 1 nm / second to form, for example, a 50 nm thick Mg film and a 150 nm thick Ag film. By this method, the organic electroluminescent element shown in FIG. 3 was produced in Example 1.

The emission characteristics of the device were evaluated by applying a forward bias DC voltage to the organic electroluminescent device fabricated in Example 1 under a nitrogen atmosphere. The emission color was red, and then the device was measured for spectrum. As a result, a spectrum having an emission peak at 640 nm was obtained as shown in FIG. Spectral measurements were performed using a spectrometer (manufactured by Otsuka Electronic Co., Ltd.) using a photodiode array as a detector. In addition, when the device was measured for voltage-luminance, a luminance of 6000 cd / m &lt; 2 &gt; was obtained, particularly at 8 V as shown in FIG.

After fabricating the organic electroluminescent device, the device was left under a nitrogen atmosphere for one month, but no deterioration of the device was observed. In addition, the device was deteriorated by performing continuous light emission while maintaining a predetermined level of current at an initial luminance of 300 cd / m 2. As a result, it took 3800 hours for the luminance to decrease by half.

<Example 2>

This embodiment is a single electron using a compound of formula 3a wherein R ² and R ³ each represent a 4-dimethylaminophenyl group, and R ⁶ and R ⁸ each represent a distyryl compound of formula 1 representing a cyano group. The manufacture of the electroluminescent element which has a heterogeneous structure is illustrated.

A 30 mm x 30 mm glass substrate, on which a 100 nm thick anode made of ITO was formed on one surface, was installed in a vacuum deposition apparatus. A metallic mask having a plurality of 2.0 mm by 2.0 mm unit openings was placed adjacent the substrate as a deposition mask. Chemical formula

Α-NPD (α-naphthylphenyldiamine) was subjected to vacuum deposition in a vacuum of 10 ⁻⁴ Pa or less to form, for example, a hole transport layer having a thickness of 50 nm. The deposition rate was 0.1 nm / second.

In addition, the compound of formula 3a used as the electron transporting material was vacuum deposited by contacting with the hole transporting layer. The thickness of the electron transporting layer (also serving as the light emitting layer) consisting of the compound of formula 3a was adjusted to 50 nm, for example, and the deposition rate was adjusted to 0.2 nm / second.

A laminated film of Mg and Ag used as the cathode material was used. More specifically, Mg and Ag were respectively deposited at a deposition rate of 1 nm / sec to form, for example, a 50 nm thick Mg film and a 150 nm thick Ag film. By this method, the organic electroluminescent element shown in FIG. 3 was produced in Example 2.

The emission characteristics of the device were evaluated by applying a forward bias DC voltage to the organic electroluminescent device fabricated in Example 2 under a nitrogen atmosphere. The emission color was red, and then the device was measured for spectrum, and the result was a spectrum having an emission peak at 640 nm as shown in FIG. In addition, when the device was measured for voltage-luminance, it was possible to obtain a luminance of 5300 cd / m 2 at 8 V, especially as shown in FIG. 9.

After fabricating the organic electroluminescent device, the device was left under a nitrogen atmosphere for one month, but no deterioration of the device was observed. In addition, the device was deteriorated by performing continuous light emission while maintaining a predetermined level of current at an initial luminance of 300 cd / m 2. As a result, it took 3200 hours for the luminance to decrease by half.

<Example 3>

This example is a double heterostructure using a compound of formula 3a, wherein the light emitting material is a distyryl compound of formula 1 wherein R ² and R ³ each represent a 4-dimethylaminophenyl group, and R ⁶ and R ⁸ each represent a cyano group. It illustrates the assembly of the electroluminescent device having a.

A 30 mm x 30 mm glass substrate, on which a 100 nm thick anode made of ITO was formed on one surface, was installed in a vacuum deposition apparatus. A metallic mask having a plurality of 2.0 mm by 2.0 mm unit openings was placed adjacent the substrate as a deposition mask. The α-NPD of the above formula was subjected to vacuum deposition in a vacuum of 10 ⁻⁴ Pa or less to form, for example, a hole transport layer having a thickness of 30 nm. The deposition rate was 0.2 nm / second.

In addition, the compound of formula 3a used as the pore material was vacuum deposited by contacting with the hole transport layer. The thickness of the light emitting layer consisting of the compound of formula 3a was adjusted to 30 nm, for example, and the deposition rate was adjusted to 0.2 nm / second.

Alq ₃ of the above formula used as the electron transporting material was contacted with the light emitting layer and vacuum deposited. The thickness of Alq ₃ was adjusted to 30 nm, for example, and the deposition rate was adjusted to 0.2 nm / second.

A laminated film of Mg and Ag used as the cathode material was used. More specifically, Mg and Ag were respectively deposited at a deposition rate of 1 nm / second to form, for example, a 50 nm thick Mg film and a 150 nm thick Ag film. By this method, the organic electroluminescent element of Example 3 shown in FIG. 4 was produced.

The emission characteristics of the device were evaluated by applying a forward bias DC voltage to the organic electroluminescent device fabricated in Example 3 under a nitrogen atmosphere. The emission color was red, and then the device was measured for spectrum, and the result was a spectrum having an emission peak at 640 nm. In addition, when the device was measured for voltage-luminance, a luminance of 6800 cd / m 2 was obtained at 8V.

After fabricating the organic electroluminescent device, the device was left under a nitrogen atmosphere for one month, but no deterioration of the device was observed. In addition, the device was deteriorated by performing continuous light emission while maintaining a predetermined level of current at an initial luminance of 300 cd / m 2. As a result, it took 4500 hours for the luminance to drop in half.

<Example 4>

Chemical formula instead of α-NPD

An organic electroluminescent device was obtained in accordance with Example 2 except that TPD (triphenyldiamine derivative) was used as the hole transporting material.

The organic electroluminescent device of this example was considered to have a red colored light as in Example 1. The results of the spectral measurements showed that the spectrum was consistent with that of the organic electroluminescent device of Example 2.

It is clear from the foregoing that the object of the present invention has been achieved. While only certain embodiments have been disclosed, alternative embodiments and various modifications will be apparent to those skilled in the art from the foregoing description. These and other alternatives are equivalents and are considered to be within the spirit and scope of the present invention.

According to the organic electroluminescent device of the present invention in which an organic layer having an emission band is provided between the anode and the cathode, the organic layer contains a distyryl compound represented by Formula 1, thereby providing an organic electroluminescent device having high luminance and ensuring stable red light emission. can do.

Claims (8)

An organic electroluminescent device comprising an anode and a cathode, and an organic layer having an emission band is disposed between the anode and the cathode, wherein the organic layer comprises an organic light emitting material including a distyryl compound of Formula 1 below. <Formula 1>

Where At least one of R ¹ , R ² , R ³ and R ⁴ is an aryl group represented by the following formula (2), The remaining (s) of R ¹ , R ² , R ³ and R ⁴ are unsubstituted phenyl groups, R ⁵ , R ⁶ , R ⁷ and R ⁸ are selected from the group consisting of hydrogen atom, cyano group, nitro group and halogen atom, provided that R ⁵ , R ⁶ , R ⁷ and R ⁸ At least one is a cyano group, a nitro group or a halogen atom. <Formula 2>

Where R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are saturated or unsaturated alkylamino groups. The organic electroluminescent device according to claim 1, wherein the organic layer comprises an electron transport layer and a hole transport layer comprising a distyryl compound of Formula 1. The organic electroluminescent device according to claim 1, wherein the organic layer comprises an organic hole transport layer and an electron transport layer including the distyryl compound of Formula 1. The organic electroluminescent device according to claim 1, wherein the organic layer comprises a hole transporting layer, a light emitting layer including the distyryl compound of Formula 1, and an electron transporting layer. An organic layer including an anode and a cathode, and an organic layer having an emission band is disposed between the anode and the cathode, and the organic layer comprises an organic light emitting material including at least one distyryl compound selected from the group consisting of Formulas 3a to 3e. An organic electroluminescent device comprising. <Formula 3a>

<Formula 3b>

<Formula 3c>

<Formula 3d>

<Formula 3e>

The organic electroluminescent device according to claim 5, wherein the organic layer comprises a hole transport layer and an electron transport layer including at least one distyryl compound selected from the group consisting of the compounds of Formulas 3a to 3e. The organic electroluminescent device according to claim 5, wherein the organic layer comprises an electron transport layer including a hole transport layer and at least one distyryl compound selected from the group consisting of the compounds of Formulas 3a to 3e. The organic electroluminescent device according to claim 5, wherein the organic layer comprises a hole transporting layer, a light emitting layer including at least one distyryl compound selected from the group consisting of compounds of Formulas 3a to 3e, and an electron transporting layer.

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