KR101407579B1 - Organic light emitting device and method of driving the same - Google Patents

Organic light emitting device and method of driving the same Download PDF

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KR101407579B1
KR101407579B1 KR1020070094210A KR20070094210A KR101407579B1 KR 101407579 B1 KR101407579 B1 KR 101407579B1 KR 1020070094210 A KR1020070094210 A KR 1020070094210A KR 20070094210 A KR20070094210 A KR 20070094210A KR 101407579 B1 KR101407579 B1 KR 101407579B1
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light emitting
green
red
layer
formed
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KR1020070094210A
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Korean (ko)
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KR20090029007A (en
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김무겸
김상열
이성훈
송정배
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삼성디스플레이 주식회사
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Abstract

An organic light emitting element and a driving method thereof are disclosed. The disclosed organic light emitting device has red, green and red pixels repeatedly formed on the same plane, and the pixels of each color include first and second electrodes arranged to be vertically spaced apart from each other; A plurality of light emitting elements which are sequentially stacked between the first electrode and the second electrode and emit light of the same color; And at least one transparent electrode formed between the light emitting elements.

Description

[0001] The present invention relates to an organic light emitting device and a driving method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device and a driving method thereof that can increase lifetime.

2. Description of the Related Art In general, an organic light emitting device (OLED) has a structure in which a hole supplied from an anode electrode and an electron supplied from a cathode electrode are combined in an organic light emitting layer formed between an anode electrode and a cathode electrode, Emitting device. In order to obtain better light emitting characteristics, a hole injection layer (HIL) and a hole transport layer (HTL) are formed between the anode electrode and the organic light emitting layer, and between the cathode electrode and the organic light emitting layer Layer structure in which an electron injection layer (EIL) and an electron transporting layer (ETL) are formed.

The organic light emitting device can be driven at a low voltage with a driving voltage of about 5 V, can realize a high luminance surface emission, has a very high response speed, and can be manufactured with a thin thickness. Besides, it has an excellent color reproducibility, has a wide viewing angle, and has an advantage that the luminescent color can be easily changed by appropriately selecting the fluorescent material. Accordingly, the organic light emitting device can be used in various fields such as a full color display device, a backlight unit for a liquid crystal display (LCD), an information display device, a vehicle display device, a lighting device and the like.

In order to improve the performance of such an organic light emitting device, a method of improving charge injection using p-type and n-type dopants, a method of blocking electrons between a red light emitting layer and a blue light emitting layer A method of inserting a buffer layer, and a method of forming a tandem structure by connecting the same elements in series have been proposed. However, the method using the p-type and n-type dopants is disadvantageous in that the dopant is expensive, and the method of inserting the buffer layer has a problem in that the lifetime of each light emitting layer varies so that the color changes with time. In addition, the method of fabricating with a tantrum structure has a problem that the driving voltage and the voltage change become large.

Meanwhile, in recent years, as the display device is gradually enlarged, the lifetime of the organic light emitting device also needs to be increased. However, in order to achieve this, the stability of the material constituting the organic light emitting device must be secured. However, the material used in the organic light emitting device has not secured such stability. Therefore, if a large-sized display device is manufactured using an existing organic light-emitting device, the lifetime of the display device is shorter than that of other display devices.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an organic light emitting device and a driving method thereof that can increase lifetime.

In order to achieve the above object,

According to an embodiment of the present invention,

Green, and red pixels that are repeatedly formed on the same plane,

The pixels of the respective colors are,

First and second electrodes spaced apart from each other;

A plurality of light emitting devices which are sequentially stacked between the first electrode and the second electrode and emit light of the same color; And

And at least one transparent electrode formed between the light emitting elements.

The material layers constituting the light emitting devices are preferably formed symmetrically with respect to the transparent electrode.

Each of the light emitting elements includes a light emitting layer of a predetermined color; A hole injection layer formed on one surface of the light emitting layer; And an electron injection layer formed on the other surface of the light emitting layer. In this case, a hole transporting layer may be further formed between the light emitting layer and the hole injecting layer, and an electron transporting layer may be further formed between the light emitting layer and the electron injecting layer.

The light transmittance of the transparent electrode may be 70% or more.

The transparent electrode may be made of indium tin oxide (ITO), indium zinc oxide (IZO), SnO 2 or ZnO. The transparent electrode may be formed of a predetermined thickness of aluminum (Al), silver (Ag), magnesium (Mg), aluminum-silver (Al-Ag) alloy or aluminum-magnesium (Al-Mg) alloy. In this case, the thickness of the transparent electrode may be 30 ANGSTROM to 200 ANGSTROM.

According to another embodiment of the present invention,

In the above-described method of driving an organic light emitting element,

(a) selecting and driving any one of red, green and blue light emitting elements among a plurality of red, green and blue light emitting elements constituting the red, green and blue pixels;

(b) selecting and driving another red, green, and blue light emitting element after a predetermined time elapses; And

(c) repeating the step (b) to select and drive the remaining red, green, and blue light emitting devices.

The selected red, green, and blue light emitting elements can be driven until a predetermined luminance required for an image is satisfied. The selected red, green, and blue light emitting devices may be formed on the same plane.

According to the organic light emitting device of the present invention, the pixels of each color include a plurality of light emitting devices, and by sequentially driving them, lifetime can be increased compared with the conventional organic light emitting device. Accordingly, a large-sized display device having an increased lifetime can be realized by using the organic light emitting device according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements, and the size and thickness of each element in the drawings may be exaggerated for clarity of explanation.

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

Referring to FIG. 1, an organic light emitting diode according to an exemplary embodiment of the present invention includes a plurality of red, green, and blue pixels 100R, 100G, and 100B repeatedly formed on the same plane. The red, green, and blue pixels 100R, 100G, and 100B may be formed on a transparent substrate (not shown) made of glass or plastic. Here, the red, green, and blue pixels 100R, 100G, and 100B include a plurality of red, green, and blue light emitting elements, respectively.

The red pixel 100R includes first and second electrodes 101 and 104 which are vertically spaced apart from each other and first and second electrodes 101 and 104 which are sequentially stacked between the first and second electrodes 101 and 104, And first and second transparent electrodes 102 and 103 formed between the third red light emitting devices 110R, 120R and 130R and the red light emitting devices 110R, 120R and 130R.

The first electrode 101 may be an anode electrode. In the bottom emission organic light emitting diode, the first electrode 101 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), SnO 2, or ZnO. The first electrode 101 may be formed of aluminum (Al), silver (Ag), magnesium (Mg), aluminum-silver (Al-Ag) alloy or aluminum- Alloys, and the like. In this case, the light transmittance of the first electrode 101 may be about 70% or more. Meanwhile, in the top emission organic light emitting device, the first electrode 101 may be a reflective electrode made of metal. The second electrode 104 may be a cathode electrode. In the bottom emission organic light emitting device, the second electrode 104 may be a reflective electrode made of a metal. Meanwhile, in the top emission organic light emitting diode, the second electrode 104 may be formed of a transparent conductive material such as ITO (indium tin oxide), IZO (indium zinc oxide), SnO 2, or ZnO, Al, Ag, Mg, Al-Ag alloy, Al-Mg alloy, or the like.

The first, second, and third red light emitting devices 110R, 120R, and 130R are sequentially stacked between the first electrode 101 and the second electrode 104. [ A first transparent electrode 102 is formed between the first red light emitting device 110R and the second red light emitting device 120R and the second red light emitting device 120R and the third red light emitting device 130R The second transparent electrode 103 is formed. The first red light emitting device 110R includes a first hole injection layer (HIL) 113, a first red light emitting layer 115R, and a first electron injection layer And an electron injection layer (EIL) 117. The first hole injection layer 113 formed on the first electrode 101 as an anode electrode is for facilitating the injection of holes. For example, MTDATA (4,4 ', 4 "-tris (3-methylphenylphenylamino ) triphenylamine, copper phthalocyanine (CuPc), poly (3,4-ethylenedioxythiophene, polystyrene sulfonate) or the like, but the present invention is not limited thereto, and the first hole- ≪ / RTI >

On the first hole injection layer 113, a first red light emitting layer 115R is formed. The first red light emitting layer 115R is a light emitting material layer that combines holes injected from the first electrode 101 and electrons injected from the first transparent electrode 102 to emit red light. The first red light emitting layer 115R may be formed by using a red dopant for the host material. A first electron injection layer 117 may be formed on the first red light emitting layer 115R. The electron injection layer 117 may be formed of, for example, LIF or LiQ (lithium quinolate). However, the present invention is not limited thereto, and the first electron injection layer 117 may be formed of various materials.

A hole transporting layer (HIL) is formed between the first hole injection layer 113 and the first red light emitting layer 115R to facilitate transport of holes, though not shown in the figure. . The first hole transport layer may be, for example, TPD (N, N'-diphenyl-N, N'-bis (3- N, N'-diphenyl-benzidine), and the like. Further, a first electron transporting layer (ETL) may be further formed between the first electron injection layer 117 and the first red emission layer 115R to facilitate transport of electrons. The first electron transporting layer may be composed of, for example, oxadiazole, triazole, phenanthroline, benzoxazole or benzthiazole, ≪ / RTI >

A first transparent electrode 102 is formed on the first electron injection layer 117. Here, the first transparent electrode 102 may be made of a material having a light transmittance of about 70% or more as a cathode electrode. The first transparent electrode 102 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), SnO 2, or ZnO. The first transparent electrode 102 may be formed of aluminum (Al), silver (Ag), magnesium (Mg), aluminum-silver (Al-Ag) ) Alloy and the like.

On the first transparent electrode 102, a second red light emitting device 120R is formed. Here, the material layers constituting the second red light emitting device 120R are formed symmetrically with the material layers constituting the first red light emitting device 110R with the first transparent electrode 102 as a center. Accordingly, the second red light emitting device 120R includes a second electron injection layer 127, a second red light emitting layer 125R, and a second hole injection layer 123 (hereinafter, referred to as " first electron injection layer ") sequentially stacked on the first transparent electrode 102 ). The second electron injection layer 127, the second red emission layer 125R and the second hole injection layer 123 are formed on the first electron injection layer 117, the first red emission layer 115R, It may be the same material layer as the injection layer 113. [ A second electron transport layer (not shown) may be further formed between the second electron injection layer 127 and the second red emission layer 125R. The second hole injection layer 123, the second red emission layer 125R, And a second hole transport layer (not shown) may be further formed between the pixel electrodes 125R.

A second transparent electrode 103 is formed on the second hole injection layer 123. Here, the second transparent electrode 103 may be made of a material having a light transmittance of about 70% or more as an anode electrode. The second transparent electrode 103 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), SnO 2, or ZnO. The second transparent electrode 103 may be formed of aluminum (Al), silver (Ag), magnesium (Mg), aluminum-silver (Al-Ag) alloy or aluminum- ) Alloy and the like.

On the second transparent electrode 103, a third red light emitting device 130R is formed. Here, the material layers constituting the third red light emitting device 130R are formed symmetrically with the material layers constituting the second red light emitting device 120R with the second transparent electrode 103 as a center. Accordingly, the third red light emitting device 130R includes a third hole injection layer 133, a third red light emitting layer 135R, and a third electron injection layer (not shown) sequentially stacked on the second transparent electrode 103 137). The third hole injection layer 133, the third red emission layer 135R and the third electron injection layer 137 are formed on the first hole injection layer 113, the first red emission layer 115R, It may be the same material layer as the injection layer 117. [ A third hole transport layer (not shown) may be further formed between the third hole injection layer 133 and the third red emission layer 135R. The third electron injection layer 137 and the third red emission layer And a third electron transporting layer (not shown) may be further formed between the first electron transporting layer 135R.

A green pixel 100G is provided on one side of the red pixel 100R on the same plane as the red pixel 100R. The green pixel 100G has the same stacking structure as the red pixel 100R described above. That is, the green pixel 100G includes first and second electrodes 101 and 104 that are vertically spaced apart from each other, and first and second electrodes 101 and 104 that are sequentially stacked between the first and second electrodes 101 and 104, Second and third green light emitting devices 110G, 120G and 130G and first and second transparent electrodes 102 and 103 formed between the green light emitting devices 110G, 120G and 130G.

The first and second electrodes 102 and 103 may be an anode electrode and a cathode electrode, respectively, like the first and second electrodes 102 and 103 constituting the red pixel 100R. The first and second electrodes 102 and 103 may be formed on the same plane as the first and second electrodes 102 and 103 constituting the red pixel 100R, respectively. Since the first and second electrodes 102 and 103 are the same electrodes as the first and second electrodes 102 and 103 constituting the red pixel 100R described above, a detailed description thereof will be omitted. The first, second and third green light emitting devices 110G, 120G and 130G are respectively connected to the first, second and third red light emitting devices 110R, 120R and 130R constituting the red pixel 100R, As shown in FIG.

The first green light emitting device 110G includes a first hole injection layer 113, a first green light emitting layer 115R, and a first electron injection layer 117 sequentially formed on the first electrode 101 . The first hole injection layer 113 and the first electron injection layer 117 may be formed of the same material as the first hole injection layer 113 and the first electron injection layer 117 constituting the red pixel 100R, Layer. The first green light emitting layer 115G is a light emitting material layer that emits green light by combining holes injected from the first electrode 101 and electrons injected from the first transparent electrode 102, . ≪ / RTI > A first hole transport layer (not shown) may be further formed between the first hole injection layer 113 and the first green emission layer 115G. The first electron injection layer 117 and the first green emission layer A first electron transporting layer (not shown) may be further formed between the pixel electrodes 115G.

A first transparent electrode 102 is formed on the first electron injection layer 117. The first transparent electrode 102 is a cathode electrode and is formed on the same plane as the first transparent electrode 102 constituting the red pixel 100R. Since the first transparent electrode 102 is the same as the first transparent electrode 102 constituting the red pixel 100R described above, detailed description thereof will be omitted. A second green light emitting device 120G is formed on the first transparent electrode 102 and material layers constituting the second green light emitting device 120G are formed on the first transparent electrode 102, And is formed symmetrically with the material layers constituting the green light emitting element 110G. The second green light emitting device 120G includes a second electron injection layer 127, a second green light emitting layer 125G, and a second hole injection layer 123 ). Here, the second electron injection layer 127, the second green emission layer 125G, and the second hole injection layer 123 are formed on the first electron injection layer 117, the first green emission layer 115G, It may be the same material layer as the injection layer 113. [ A second electron transport layer (not shown) may be further formed between the second electron injection layer 127 and the second green emission layer 125G. The second hole injection layer 123, And a second hole transport layer (not shown) may be further formed between the pixel electrodes 125G.

A second transparent electrode 103 is formed on the second hole injection layer 123. The second transparent electrode 103 is formed on the same plane as the second transparent electrode 103 constituting the red pixel 100R as the anode electrode. Since the second transparent electrode 103 is the same as the second transparent electrode 103 constituting the red pixel 100R described above, detailed description thereof will be omitted. A third green light emitting device 130G is formed on the second transparent electrode 103 and material layers constituting the third green light emitting device 130G are formed on the second transparent electrode 103, And is formed symmetrically with the material layers constituting the green light emitting element 120G. Accordingly, the third green light emitting device 130G includes a third hole injection layer 133, a third green light emitting layer 135G and a third electron injection layer 137 sequentially stacked on the second transparent electrode 103 ). The third hole injection layer 133, the third green emission layer 135G, and the third electron injection layer 137 are formed on the first hole injection layer 113, the first green emission layer 115G, It may be the same material layer as the injection layer 117. [ A third hole transport layer (not shown) may be further formed between the third hole injection layer 133 and the third green emission layer 135G. The third electron injection layer 137 and the third green emission layer And a third electron transporting layer (not shown) may be further formed between the pixel electrode 135G.

On one side of the green pixel 100G, a blue pixel 100B is provided on the same plane as the red and green pixels 100R and 100G. The blue pixel 100B has the same lamination structure as the red and green pixels 100R and 100G described above. The blue pixel 100B includes first and second electrodes 101 and 104 that are vertically spaced apart from each other and first and second electrodes 101 and 104 that are sequentially stacked between the first and second electrodes 101 and 104, And first and second transparent electrodes 102 and 103 formed between the first and second blue light emitting devices 110B and 120B and the blue light emitting devices 110B and 120B.

The first and second electrodes 102 and 103 may be an anode electrode and a cathode electrode as described above and the first and second electrodes 101 and 104 may be formed of a red pixel 100R or a green pixel 100G The first and second electrodes 101 and 104 may be formed on the same plane as the first and second electrodes 101 and 104. The first blue light emitting device 110B includes a first hole injection layer 113, a first blue light emitting layer 115B, and a first electron injection layer 117 sequentially formed on the first electrode 101 . Here, the first blue light emitting device 110B may be formed on the same plane as the first red light emitting device 110R and the first green light emitting device 110G. The first hole injection layer 113 and the first electron injection layer 117 are respectively connected to a first hole injection layer 113 and a first electron injection layer 117 constituting a red pixel 100R or a green pixel 100G, ). ≪ / RTI > The first blue light emitting layer 115B is a light emitting material layer that couples holes injected from the first electrode 101 and electrons injected from the first transparent electrode 102 to emit blue light. . ≪ / RTI > A first hole transport layer (not shown) may be further formed between the first hole injection layer 113 and the first blue emission layer 115B. The first electron injection layer 117 and the first blue emission layer And a first electron transport layer (not shown) may be further formed between the second electrode 115B.

A first transparent electrode 102 is formed on the first electron injection layer 117. The first transparent electrode 102 is a cathode electrode and is formed on the same plane as the first transparent electrode 102 constituting the red pixel 100R or the green pixel 100G. A second blue light emitting device 120B is formed on the first transparent electrode 102 and material layers constituting the second blue light emitting device 120B are formed on the first transparent electrode 102, And is formed symmetrically with the material layers constituting the blue light emitting element 110B. Accordingly, the second blue light emitting device 120B includes a second electron injection layer 127, a second blue light emitting layer 125B, and a second hole injection layer 123, which are sequentially stacked on the first transparent electrode 102 ). Here, the second electron injection layer 127, the second blue emission layer 125B, and the second hole injection layer 123 may include a first electron injection layer 117, a first blue emission layer 115B, It may be the same material layer as the injection layer 113. [ A second electron transport layer (not shown) may be further formed between the second electron injection layer 127 and the second blue emission layer 125B. The second hole injection layer 123 and the second blue emission layer And a second hole transporting layer (not shown) may be further formed between the pixel electrodes 125B.

A second transparent electrode 103 is formed on the second hole injection layer 123. The second transparent electrode 103 is formed on the same plane as the red pixel 100R as the anode electrode or the second transparent electrode 103 constituting the green pixel 100G. A third blue light emitting device 130B is formed on the second transparent electrode 103 and material layers constituting the third blue light emitting device 130B are formed on the second transparent electrode 103, And is formed symmetrically with the material layers constituting the second blue light emitting device 120B. The third blue light emitting device 130B includes a third hole injection layer 133, a third blue light emitting layer 135B, and a third electron injection layer 137 sequentially stacked on the second transparent electrode 103 ). The third hole injection layer 133, the third blue emission layer 135B, and the third electron injection layer 137 are formed on the first hole injection layer 113, the first green emission layer 115B, It may be the same material layer as the injection layer 117. [ A third hole transport layer (not shown) may be further formed between the third hole injection layer 133 and the third blue emission layer 135B. The third electron injection layer 137 and the third blue emission layer And a third electron transporting layer (not shown) may be further formed between the second electrode 135B.

Hereinafter, a method of driving an organic light emitting diode according to an embodiment of the present invention shown in FIG. 1 will be described. FIGS. 2 to 4 are views for explaining a driving method of an organic light emitting diode according to an embodiment of the present invention shown in FIG. 2 to 4 show an example of a bottom emission type organic light emitting device.

Referring to FIG. 2, three red, green, and blue light emitting devices 110R, 120R, 130R, 110G, 120G, 130G, 110B, 120B, and 120B, respectively constituting red, green, and blue pixels 100R, The first red light emitting element 110R, the first green light emitting element 110G, and the first blue light emitting element 110B among the red, The driving of the first red light emitting device 110R, the first green light emitting device 110G and the first blue light emitting device 110B includes driving the first electrode 101 as the anode electrode and the first transparent electrode 102 as the cathode electrode, By applying a predetermined voltage. When a voltage is applied between the first electrode 101 and the first transparent electrode 102, holes and electrons are emitted from the first electrode 101 and the first transparent electrode 102, respectively, The first green light emitting layer 115G and the first blue light emitting layer 115B so that the red light R, the green light G and the blue light B are emitted. The emitted red light R, green light G and blue light B are emitted to the outside through the first electrode 101 to form an image.

The first red light emitting element 110R, the first green light emitting element 110G and the first blue light emitting element 110B may emit red light R, green light R, and blue light R, G, and B emitted from the respective light emitting elements 110R, 110G, G) and the blue light B are continuously driven to form an image until the luminance required for the image is satisfied. After a predetermined time has elapsed, the red light R, the green light G and the blue light B emitted from the first red light emitting element 110R, the first green light emitting element 110G and the first blue light emitting element 110B, If the luminance required for the image is not satisfied, the driving of the first red light emitting device 110R, the first green light emitting device 110G, and the first blue light emitting device 110B is terminated. Accordingly, the first red light emitting device 110R, the first green light emitting device 110G, and the first blue light emitting device 110B have a lifetime.

3, after the driving of the first red light emitting device 110R, the first green light emitting device 110G, and the first blue light emitting device 110B is completed, the second red light emitting device 120R, The second green light emitting element 120G and the second blue light emitting element 120B are selected and driven. The driving of the second red light emitting device 120R, the second green light emitting device 120G and the second blue light emitting device 120B is performed by driving the first transparent electrode 102 which is a cathode electrode and the second transparent electrode 103 Quot;). ≪ / RTI > When a voltage is applied between the first transparent electrode 102 and the second transparent electrode 103 as described above, electrons and holes from the first transparent electrode 102 and the second transparent electrode 103, respectively, Red light R, green light G and blue light B are emitted as they are injected into the red light emitting layer 125R, the second green light emitting layer 125G and the second blue light emitting layer 125B. The emitted red light R, green light G and blue light B are emitted to the outside through the first transparent electrode 102 and the first electrode 101 to form an image.

The second red light emitting device 120R, the second green light emitting device 120G and the second blue light emitting device 120B may emit red light R, green light R, and blue light R, G, and B emitted from the respective light emitting devices 120R, 120G, G) and the blue light B are continuously driven to form an image until the luminance required for the image is satisfied. After a predetermined time has elapsed, the red light R, the green light G and the blue light B emitted from the second red light emitting device 120R, the second green light emitting device 120G and the second blue light emitting device 120B, If the luminance required for the image is not satisfied, the driving of the second red light emitting device 120R, the second green light emitting device 120G and the second blue light emitting device 120B is terminated. Accordingly, the second red light emitting device 120R, the second green light emitting device 120G, and the second blue light emitting device 120B have a lifetime.

4, after the driving of the second red light emitting device 120R, the second green light emitting device 120G, and the second blue light emitting device 120B is completed, the third red light emitting device 130R, The third green light emitting element 130G and the third blue light emitting element 130B are finally selected and driven. The driving of the third red light emitting device 130R, the third green light emitting device 130G and the third blue light emitting device 130B is performed by driving the second transparent electrode 103, which is an anode electrode, and the second electrode 104, By applying a predetermined voltage. When a voltage is applied between the second transparent electrode 103 and the second electrode 104 as described above, holes and electrons from the second transparent electrode 103 and the second electrode 104, respectively, The third green light emitting layer 135G and the third blue light emitting layer 135B so that the red light R, the green light G and the blue light B are emitted. The red light R, the green light G and the blue light B emitted as described above are emitted to the outside through the second and first transparent electrodes 103 and 102 and the first electrode 101 to form an image.

As described above, in the organic light emitting device according to the embodiment of the present invention, the red, green, and blue pixels 100R, 100G, and 100B are repeatedly formed on the same plane, and each of the red, 100G and 100B include three red, green and blue light emitting devices 110R, 120R, 130R, 110G, 120G, 130G, 110B, 120B and 120B, respectively. The first red light emitting device 110R, the first green light emitting device 110G, and the first blue light emitting device 110B are first selected and driven in the organic light emitting device having such a structure, When the lifetime of the device 110R, the first green light emitting device 110G and the first blue light emitting device 110B is shortened, the second red light emitting device 120R, the second green light emitting device 120G, The blue light emitting element 120B is selected and driven. When the lifetime of the second red, green, and blue light emitting devices 120R, 120G, and 120B is shortened, the third red light emitting device 130R, 130G and the third blue light emitting device 130B. Therefore, the organic light emitting diode according to the embodiment of the present invention can increase its lifetime three times as compared with the conventional organic light emitting device in which the red, green, and blue pixels each include one red, green, and blue light emitting devices.

In the above embodiments, the first and second electrodes 101 and 104 are an anode electrode and a cathode electrode, respectively. However, the first and second electrodes 101 and 104 may be a cathode electrode and an anode electrode, respectively . In this case, the first and second transparent electrodes 102 and 103 are respectively an anode electrode and a cathode electrode. Although the case where the pixels 100R, 100G, and 100B of each color include three light emitting devices has been described in the above embodiments, the present invention is not limited to this, Or four or more light emitting elements. Also in this case, transparent electrodes are formed between the light emitting elements as in the above-described embodiment, and the constituent material layers of the light emitting elements adjacent to each other with the transparent electrode therebetween are formed symmetrically with respect to the transparent electrode. When the pixels 100R, 100G, and 100B of the respective colors include even number of light emitting devices, the first and second electrodes 101 and 104 may all be anode electrodes, or both may be cathode electrodes.

 While the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, the true scope of the present invention should be determined by the appended claims.

1 is a schematic cross-sectional view of an organic light emitting device according to an embodiment of the present invention.

FIGS. 2 to 4 are views for explaining a driving method of an organic light emitting diode according to an embodiment of the present invention shown in FIG.

Description of the Related Art

100R ... red pixel 100G ... green pixel

100B ... blue pixel 101 ... first electrode

102 ... first transparent electrode 103 ... second transparent electrode

104 ... second electrode 110R ... first red light emitting element

110G ... first green light emitting element 110B ... first blue light emitting element

113 ... first hole injection layer 115R ... first red light emitting layer

115G ... first green light emitting layer 115B ... first blue light emitting layer

117 ... first electron injection layer 120R ... second red light emitting element

120G ... second green light emitting element 120B ... second blue light emitting element

123 ... second hole injection layer 125R ... second red light emitting layer

125G ... second green light emitting layer 125B ... second blue light emitting layer

127 ... second electron injection layer 130R ... third red light emitting element

130G ... second green light emitting element 130B ... third blue light emitting element

133 ... third hole injection layer 135R ... third red light emitting layer

135G ... third green light emitting layer 135B ... third blue light emitting layer

137 ... third electron injection layer

Claims (11)

  1. Green, and blue pixels that are repeatedly formed on the same plane,
    The pixels of the respective colors are,
    First and second electrodes spaced apart from each other;
    A plurality of light emitting devices which are sequentially stacked between the first electrode and the second electrode and emit light of the same color; And
    And at least one transparent electrode formed between the light emitting elements,
    Wherein the material layers constituting the light emitting devices are formed symmetrically with respect to the transparent electrode.
  2. delete
  3. The method according to claim 1,
    Each of the light emitting elements includes a light emitting layer of a predetermined color; A hole injection layer formed on one surface of the light emitting layer; And an electron injection layer formed on the other surface of the light emitting layer.
  4.  The method of claim 3,
    A hole transport layer formed between the light emitting layer and the hole injection layer; And an electron transport layer formed between the light emitting layer and the electron injection layer.
  5. The method according to claim 1,
    Wherein the transparent electrode has a light transmittance of 70% or more.
  6. The method according to claim 1,
    Wherein the transparent electrode is made of ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), SnO 2 or ZnO.
  7.  The method according to claim 1,
    Wherein the transparent electrode is made of aluminum (Al), silver (Ag), magnesium (Mg), aluminum-silver (Al-Ag) alloy or aluminum- .
  8.  8. The method of claim 7,
    Wherein the thickness of the transparent electrode is 30 ANGSTROM to 200 ANGSTROM.
  9. Green, and blue pixels repeatedly formed on the same plane, wherein the pixels of the respective colors include first and second electrodes provided so as to be vertically spaced apart from each other, and first and second electrodes disposed between the first and second electrodes, A method of driving an organic light emitting diode comprising a plurality of light emitting devices that sequentially emit light of the same color and at least one transparent electrode formed between the light emitting devices,
    (a) selecting and driving any one of red, green and blue light emitting elements among a plurality of red, green and blue light emitting elements constituting the red, green and blue pixels;
    (b) selecting and driving another red, green, and blue light emitting element after a predetermined time elapses; And
    (c) repeating the step (b) to select and drive the remaining red, green, and blue light emitting devices.
  10. 10. The method of claim 9,
    Wherein the selected red, green, and blue light emitting elements are driven until a predetermined luminance required for an image is satisfied.
  11. 10. The method of claim 9,
    Wherein the selected red, green, and blue light emitting devices are formed on the same plane.
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JPH06302383A (en) * 1993-04-16 1994-10-28 Sharp Corp El element and liquid crystal display device
JP2002287668A (en) * 2001-03-27 2002-10-04 Seiko Epson Corp Organic el display device and electronic appliance
KR20070067155A (en) * 2004-10-22 2007-06-27 이스트맨 코닥 캄파니 White oleds having color-compensated electroluminescent unit
KR20070076521A (en) * 2006-01-18 2007-07-24 주식회사 엘지화학 Oled having stacked organic light-emitting units

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Publication number Priority date Publication date Assignee Title
JPH06302383A (en) * 1993-04-16 1994-10-28 Sharp Corp El element and liquid crystal display device
JP2002287668A (en) * 2001-03-27 2002-10-04 Seiko Epson Corp Organic el display device and electronic appliance
KR20070067155A (en) * 2004-10-22 2007-06-27 이스트맨 코닥 캄파니 White oleds having color-compensated electroluminescent unit
KR20070076521A (en) * 2006-01-18 2007-07-24 주식회사 엘지화학 Oled having stacked organic light-emitting units

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