KR100965590B1 - Organic Light Emitting Display Device - Google Patents

Abstract

The present invention relates to an organic light emitting diode display, and more particularly, to a white organic light emitting diode display having high color reproducibility while reducing power consumption.

An organic light emitting diode display according to the present invention includes a first electrode formed on a substrate; A first common layer formed by sequentially stacking a first hole injection layer and a first hole transporting layer with an organic material on the first electrode; A first light emitting layer formed by sequentially stacking a blue light emitting layer and a green light emitting layer as an organic material on the first hole transport layer; A second common layer formed by sequentially stacking a first electron transport layer, a charge generation layer, a second hole injection layer, and a second hole transport layer on the first light emitting layer; A second light emitting layer formed by stacking a red light emitting layer with an organic material on the second hole transport layer; A third common layer formed by sequentially stacking a second electron transport layer and an electron injection layer on the second light emitting layer; And a second electrode formed on the third common layer, wherein the charge generating layer generates charge supplied to the first light emitting layer and the second light emitting layer, and the blue light emitting layer and the green light emitting layer of the first light emitting layer are the same. And a host material.

Organic light emitting display, white organic light emitting display, charge generating layer

Description

Organic Light Emitting Display Device

The present invention relates to an organic light emitting diode display, and more particularly, to a white organic light emitting diode display having high color reproducibility while reducing power consumption.

With the development of the information society, it is required to develop a new image display device that improves disadvantages such as heavy weight and large volume of the conventional CRT (Cathode Ray Tube).

Accordingly, liquid crystal display devices (LCDs), organic light emitting diode display devices (OLEDs), plasma panel display devices (PDPs), surface-conduction electron-emitter display devices (SEDs), and the like. The same various flat panel display devices are attracting attention.

Among them, the organic light emitting diode display is an organic light emitting device that is a self-luminous device in which light of a specific wavelength is generated by recombination of electrons and holes to form excitons and energy from the formed excitons. Using a diode, the display characteristics such as contrast ratio and response time are excellent, and a flexible display can be easily implemented to attract attention as an ideal next-generation display.

In general, an organic light emitting display device has a cathode electrode for injecting electrons and an anode electrode for injecting holes, and emits electrons and holes from the cathode and anode electrodes, respectively. The device emits light, and emits light when an exciton, which is a combination of injected electrons and holes, drops from an excited state to a ground state.

Due to this principle, unlike the conventional thin film liquid crystal display, since a separate light source is not required, there is an advantage in that the volume and weight of the device can be reduced. In addition, the organic EL device exhibits high quality panel characteristics (low power, high brightness, high reaction rate, low weight).

Due to these characteristics, the organic light emitting display device is used in portable digital applications such as a mobile communication terminal, a car navigation system (CNS), a camcorder, a digital camera, and the like. It is considered a powerful next generation display.

In addition, since the manufacturing process is simple, there is an advantage that can reduce the production cost more than the conventional liquid crystal display.

However, conventional organic light emitting display devices have a structure in which pixels emitting red, green, and blue light are formed separately. In this case, as the lifespan of each color is not constant, a specific color of the organic light emitting display device may be changed over time. There is a problem that the wavelength is changed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a white organic light emitting display device in which each pixel emits white light without emitting a separate color.

An organic light emitting diode display according to the present invention includes a first electrode formed on a substrate; A first common layer formed by sequentially stacking a first hole injection layer and a first hole transporting layer with an organic material on the first electrode; A first light emitting layer formed by sequentially stacking a blue light emitting layer and a green light emitting layer as an organic material on the first hole transport layer; A second common layer formed by sequentially stacking a first electron transport layer, a charge generation layer, a second hole injection layer, and a second hole transport layer on the first light emitting layer; A second light emitting layer formed by stacking a red light emitting layer with an organic material on the second hole transport layer; A third common layer formed by sequentially stacking a second electron transport layer and an electron injection layer on the second light emitting layer; And a second electrode formed on the third common layer, wherein the charge generating layer generates charge supplied to the first light emitting layer and the second light emitting layer, and the blue light emitting layer and the green light emitting layer of the first light emitting layer are the same. And a host material.

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An organic light emitting diode display according to an exemplary embodiment of the present invention may be formed by stacking a first emission layer and a second emission layer that emit light of different colors, and may emit white light by mixing light emitted from the first emission layer and the second emission layer. Has the effect. At this time, the light emitting mechanism of the first light emitting layer emits light through the fluorescence mechanism, and the light emitting mechanism of the second light emitting layer emits light through the phosphorescence mechanism to realize high color reproducibility.

In addition, in the organic light emitting diode display according to the embodiment of the present invention, the first light emitting layer, in particular, the first light emitting layer emitting blue and green light, and the second light emitting layer emitting the second light emitting layer, in particular red light, phosphorescent light emission, respectively, High color reproduction is achieved.

Next, an organic light emitting diode display according to an exemplary embodiment of the present invention will be described in detail.

An organic light emitting display device according to an embodiment of the present invention includes a first electrode formed on a substrate, a first common layer formed on the first electrode, a first light emitting layer on the first common layer, and the first electrode. A second common layer formed on the emission layer, a second emission layer formed on the second common layer, a third common layer formed on the second emission layer, and a second electrode formed on the third common layer It is characterized by.

In the organic light emitting diode display according to the exemplary embodiment of the present invention, the second common layer includes a charge generating layer, and the charge generating layer is formed of lithium.

The organic light emitting diode display according to the embodiment of the present invention is characterized in that the first light emitting layer is a fluorescent light emitting layer and the second light emitting layer is a phosphorescent light emitting layer.

The organic light emitting diode display according to the exemplary embodiment of the present invention is characterized in that the first light emitting layer is formed by sequentially stacking a blue light emitting layer and a green light emitting layer, and the second light emitting layer is a red light emitting layer. At this time, the blue light emitting layer and the green light emitting layer is characterized in that formed using the same host material.

Next, an organic light emitting diode display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a configuration of an organic light emitting diode display according to an exemplary embodiment of the present invention.

As shown in FIG. 1, an organic light emitting diode display according to an exemplary embodiment of the present invention includes a first electrode 200 formed on a substrate 100 and a first common layer formed on the first electrode 200. 300, the first light emitting layer 400 on the first common layer 300, the second common layer 500 formed on the first light emitting layer 400, and the second common layer 500. The second light emitting layer 600 formed on the upper portion, the third common layer 700 formed on the second light emitting layer 600, and the second electrode 800 formed on the third common layer 700, It features.

The substrate 100 may be a transparent substrate having a high transmittance, for example, a glass substrate made of glass, and a plastic substrate may also be used to implement a flexible display. .

The first electrode 200 formed on the substrate 100 may be, for example, an anode electrode. When the first electrode is an anode electrode, the first electrode 200 may be formed of, for example, indium-tin oxide (ITO), indium-zinc oxide (IZO), or indium-tin-. It may be desirable to form a transparent and electrically conductive metal such as indium tin zinc oxide (ITZO) or aluminum oxide doped zinc oxide (AZO).

The first common layer 300 formed on the first electrode 200 serves to transfer holes supplied from the first electrode to the first light emitting layer 400 to be described later, for example. It may be configured to include a layer 310, the first hole transport layer 320.

As the first hole injection layer 310 (HIL: Hole Injection Layer), for example, DNTPD ((N, N ')-[p-di (m-tolyl) aminophenyl] -N, N'-diphenyl benzidine ), m-2 TNATA (4,4 ', 4' '-tris (N- (2-naphthyl) -N-phenyl-amino) triphenylamine), CuPc (Copper Phthalocyanine), etc. Preferably, it may be formed using a pyrazin derivative such as 2,3-di (pyrazin-2-yl).

For example, NPB (4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl) or tri-biphenyl may be used as the first hole transporting layer 320 (HTL). It is possible to select and use from a tri-biphenyl-amine derivative, etc., preferably NPD (N, N'-di-1-naphthyl-N, N'-diphenyl-1,1'-biphenyl -4,4'diamine) may be used. For reference, the chemical formula of NPD is shown in Chemical Formula 1 below.

For example, the first light emitting layer 400 may be formed by sequentially stacking the blue light emitting layer 410 and the green light emitting layer 420.

The blue light emitting layer 410 may include, for example, MADN (2-methyl-9,10-di (2-naphthyl) anthracene), ADN (9,10-di (2-naphthyl) anthracene), or 10- (naphthalen). -3-yl) -9- (3- (bi-phenyl) anthracene, 10- (naphthalen-3-yl) -9- (4- (naphthalen-3-yl) phenyl) anthracene, 9- (naphthalen-2 -yl) -1- (naphthalen-3-yl) anthracene derivatives may be used as the host material, and a dopant material may be used as a pyrene derivative.

Preferably, a 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative is used as a host material, and a pyrene derivative is used as a dopant material. It can also be implemented.

In addition, the green light emitting layer 420 is, for example, MADN (2-methyl-9,10-di (2-naphthyl) anthracene), ADN (9,10-di (2-naphthyl) anthracene), 10- (naphthalen-3-yl) -9- (3- (bi-phenyl) anthracene, 10- (naphthalen-3-yl) -9- (4- (naphthalen-3-yl) phenyl) anthracene, N2- (9 , 9-dimethyl-9H-fluoren-2-yl) -9,10-di (naphthalen-2-yl) anthracene), 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative It may be selected from a material such as and used as a host material. Preferably, a 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative is used as the host material, and 2, N2, N6, N6,9,10-hexaphenyl Anthracene-2,6-diamine may be used as the dopant material.

Preferably, 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative is used as the host material, and 2, N2, N6, N6,9,10-hexaphenyl anthracene is used as the dopant material. -2,6-diamine will be available.

That is, in the first light emitting layer of the organic light emitting diode display according to the exemplary embodiment of the present invention, it is preferable to use the same material as the host material of each of the light emitting layers sequentially stacked. As such, by using the same material as the host material of the light emitting layers having different colors successively stacked, not only the lifespan of the two colors but also the effect of making the intensity of each wavelength of the light emitted to be similar are similar. In other words, when the lifespan of the two colors are similar, abnormal color defects due to the change of intensity of a specific color over time can be reduced, and the two colors have a similar lifespan, thereby facilitating device management.

In addition, the blue light emitting layer and the green light emitting layer is characterized in that the light emission through a fluorescence mechanism (fluorescence mechanism).

The second common layer 500 formed on the first emission layer 400 may include, for example, a first electron transport layer (ETL) 510 and a charge generation layer 520 (CGL). ), A second hole injection layer 530, and a second hole transport layer 540. The second common layer 500 transmits electrons to the first common layer and also plays a role of transferring holes to the second emission layer, which will be described later.

The first electron transport layer 510 is selected from, for example, Alq3 (8-hydroxyquinoline aluminum), 2,6,9,10-tetraphenyl anthracene derivative, Bphen (4,7-diphenyl-1,10-phenanthroline), and the like. Can be formed. Preferably, Phenanthroline derivatives may be used.

The charge generating layer 520 is positioned between the first light emitting layer 400 and the second light emitting layer 600, and when a voltage is applied between the first electrode 200 and the second electrode 800, holes are provided. And separating and supplying electrons to each light emitting layer. In other words, the charge generation layer 520 generates charges, that is, electrons and holes so as to be smoothly supplied to the two light emitting layers while being connected to the first light emitting layer 400 and the second light emitting layer 600 in series. do.

In particular, in the organic light emitting diode display according to the exemplary embodiment of the present invention, the charge generation layer is formed by selecting from lithium (Li), lithium (Magnesium, Mg), aluminum (Aluminium, Al), silver (Ag), Preferably it may be formed of lithium (Lithium, Li), in this case the thickness is formed to less than 30Å. As such, when lithium is used as the charge generation layer, it is possible to implement an organic light emitting display device having higher efficiency.

The second hole injection layer 530, like the first hole injection layer 310, is NTPD ((N, N ′)-[p-di (m-tolyl) aminophenyl-N, N'-diphenyl benzidine) , m-2TNATA (4,4 ', 4-tris (N- (2-naphthyl) -N-phenyl-amino) triphenylamine), CuPc (Copper Phthalocyanine) and the like can be selected and used. It would be desirable to form using 2,3-di (pyrazin-2-yl) pyrazin derivatives.

Similar to the first hole transport layer 320, the second hole transport layer 540 may also be NPB (4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl) or tri-biphenyl. It is possible to select and use from a tri-biphenyl-amine derivative, etc., preferably NPD (N, N'-di-1-naphthyl-N, N'-diphenyl-1,1'-biphenyl -4,4'diamine) may be used.

The second emission layer 600 formed on the second common layer 500 may be formed of, for example, a red emission layer. That is, in the organic light emitting diode display according to the exemplary embodiment of the present invention, the first light emitting part and the second light emitting part formed by stacking the first light emitting part and the common layer between the light emitting different light and the first light emitting part The light emitted from and the light emitted from the second light emitter are mixed with each other to realize white light.

In addition, the red light emitting layer will be preferable to emit light through a phosphorescence mechanism (phosphorescence mechanism). As such, the blue and green light emitting layers emit light through the fluorescence mechanism, and the red light emitting layer emits light through the phosphorescence mechanism, resulting in high color reproducibility.

In addition, the red light-emitting layer is BAlq (bis (2-methyl-8-quinolinolato) (para-phenylphenolato) aluminum (III)), CBP (4,4′-N, N′-dicarbozole biphenyl), BCP (2,9 -dimethyl-4,7-dipheny-1,10-phenanthroline), bis (2-methyl-8-quinolinolato derivatives, etc.) can be selected as a host material, dopant material as iridium complex (biio) 2Ir (acac) , DCJTB (4- (dicyanomethylene) -2-t-butyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl) -4 H-pyran), etc. Preferably, Bis (2-methyl-8-quinolinolato derivatives may be used as the host material, and iridium complex (biio) 2Ir (acac) may be used as the dopant material.

The third common layer 700 formed on the second emission layer 600 includes, for example, a second electron transport layer 710 formed on the second emission layer and an electron injection layer 720 formed on the second electron transport layer. It may be configured to include). For example, the third common layer serves to transfer electrons supplied from the second electrode, which will be described later, to the second emission layer.

The second electron transport layer 710 is, for example, Alq3 (8-hydroxyquinoline aluminum), 2,6,9,10-tetraphenyl anthracene derivative, Bphen (4,7-diphenyl-), like the first electron transport layer. 1,10-phenanthroline) may be formed. Preferably, Phenanthroline derivatives may be used.

The electron injection layer 720 may be selected from, for example, Liq (8-hydroxyquinolatolithium), Li, or the like, and preferably LiF may be used.

The second electrode 800 formed on the third common layer 700 may be, for example, a cathode electrode. When the second electrode is a cathode, the second electrode 800 may be formed of a single layer selected from, for example, aluminum (Al), silver (Ag), or the like, and may have a multilayer structure formed by stacking them.

Although not shown, the first light emitting layer and the second light emitting layer may be connected in series and connected to one power source. That is, compared with the case where the red, green, and blue light emitting layers are connected to separate power sources, the driving voltage can be lowered.

In addition, the organic light emitting diode display according to the exemplary embodiment of the present invention preferably has a bottom emission structure so that white light is emitted toward the transparent electrode.

Although not shown, the organic light emitting diode display according to the exemplary embodiment of the present invention may further include a color filter formed on an upper surface or a lower surface of the substrate.

FIG. 2 is a graph illustrating an intensity peak of light for each wavelength of each sample after fabricating a sample of an organic light emitting diode display according to an exemplary embodiment of the present invention. At this time, the sample was made of two types, sample 1 (BG / R_1) and sample 2 (BG_R_2).

Sample 1 used a glass substrate, and ITO was used as the first electrode and aluminum (1500 mV) as the second electrode. Further, the first hole injection layer and the second hole injection layer were formed by depositing 50 Å of a (2,3-di (pyrazin-2-yl) pyrazin derivative. The first hole transport layer and the second hole transport layer formed NPD. It was formed using, the thickness was formed to 800Å.

In addition, the blue light-emitting layer formed a 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative to have a thickness of 100 로 as a host material, and the pyrene-based derivative was formed as a dopant material ( 4.5% as a dopant material. The green light-emitting layer also formed a 9- (naphthalen-2-yl) -1- (naphthalen-3-yl) anthracene derivative to have a thickness of 300 로 as a host material, and a pyrene derivative was used as a dopant material. 3.6% of the material was added. The red light-emitting layer was formed with a bis (2-methyl-8-quinolinolato derivative) having a thickness of 350 유도체 as a host material, and 9% of iridium complex (biio) 2Ir (acac) was added as a dopant material.

The charge generating layer was made of lithium and had a thickness of 10 kPa.

As the first electron transporting layer and the second electron transporting layer, a Phenanthroline derivative was used. The first electron transporting layer was formed to have a thickness of 400 GPa and the second electron transporting layer was 200 GPa. The electron injection layer was formed of LiF, and formed to have a thickness of 5 μs.

On the other hand, Sample 2 was produced to have the same constitution as in Sample 1 except that the addition ratios of the dopants of the blue light emitting layer and the green light emitting layer were 3.5% and 3.3%, respectively.

As can be seen from FIG. 2, it was found that Sample 1 and Sample 2 both have poles at about 460 nm, 530 nm, and 630 nm.

Table 1 shows the conditions for measuring driving voltage, efficiency, and color coordinates of Sample 1 and Sample 2 at 25 ° C, 1 atm, and 1000 nits of brightness.

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Driving voltage (V)

efficiency

Color coordinates (CIE)
cd / A lm / W x y Sample 1 6.0 25.7 13.4 0.377 0.343 Sample 2 6.3 31.3 15.6 0.360 0.397

As can be seen from Table 1, in the organic light emitting diode display according to the exemplary embodiment of the present invention, the efficiency of the device reaches 31.3 cd / A, and the driving voltage also has a driving voltage that is not high near 6.0V. And it was found.

3 illustrates a life curve of the organic light emitting diode display according to the exemplary embodiment of the present invention.

The life curve of FIG. 3 was measured at 5000 nits, in which case the life was 1450 hours. If the acceleration factor based on luminance 1000nit is 1.7, it has a life span of 22000 or more.

 As described above, in the organic light emitting diode display according to the exemplary embodiment of the present invention, the light emitting layers emitting different light are connected in series, and the light emitted from each light emitting layer is mixed to realize white light. A light emitting display device can be implemented.

In addition, the organic light emitting diode display according to the exemplary embodiment may implement a device having a long lifespan by optimizing a combination of materials used in the organic layer and the charge generation layer. In addition, each light emitting layer has an effect of obtaining a high color reproducibility by allowing the light emitting layer to emit light by different mechanisms.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is a cross-sectional view illustrating an example of an organic light emitting diode display according to an exemplary embodiment of the present invention.

2 is a graph illustrating intensity peaks of wavelengths of Samples 1 and 2 of the organic light emitting diode display according to the exemplary embodiment of the present invention.

3 is a graph illustrating a life curve of an organic light emitting diode display according to an exemplary embodiment of the present invention.

Claims (8)

A first electrode formed on the substrate; A first common layer formed by sequentially stacking a first hole injection layer and a first hole transporting layer with an organic material on the first electrode; A first light emitting layer formed by sequentially stacking a blue light emitting layer and a green light emitting layer as an organic material on the first hole transport layer; A second common layer formed by sequentially stacking a first electron transport layer, a charge generation layer, a second hole injection layer, and a second hole transport layer on the first light emitting layer; A second light emitting layer formed by stacking a red light emitting layer with an organic material on the second hole transport layer; A third common layer formed by sequentially stacking a second electron transport layer and an electron injection layer on the second light emitting layer; And A second electrode formed on the third common layer, The charge generating layer generates a charge supplied to the first light emitting layer and the second light emitting layer, And the blue light emitting layer and the green light emitting layer of the first light emitting layer include the same host material. delete The method of claim 1, And the first light emitting layer emits light by a fluorescence mechanism and the second light emitting layer emits light by a phosphorescence mechanism. delete The method of claim 1, The charge generation layer is formed by selecting from lithium (Li), Li, magnesium (Magnesium, Mg), aluminum (Aluminium, Al), silver (Ag). delete The method of claim 1, The first emission layer and the second emission layer are connected to each other between the first electrode and the second electrode through the second common layer. delete

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