KR101800658B1 - Organic light emitting device - Google Patents

Abstract

The present invention relates to an organic light emitting device for improving luminance nonuniformity. The organic light emitting device comprising: a substrate; A first electrode layer formed on the substrate and supplied with a first power; An organic light emitting layer on the first electrode layer; A second electrode layer formed on the organic light emitting layer and supplied with a second power supply having an opposite polarity to the first power supply; One or more conductors spaced apart from the second electrode layer and positioned adjacent to the second electrode layer and supplied with a third power supply having an opposite polarity to the second power supply; And a control unit.
According to this configuration, it is possible to provide an organic light emitting device capable of improving luminance non-uniformity by forming an electric field in a portion where the luminance is reduced in the organic light emitting device.

Description

[0001] The present invention relates to an organic light emitting device,

The present invention relates to an organic light emitting device for improving luminance nonuniformity.

Generally, an organic light emitting device includes an anode, an organic light emitting layer positioned on the anode, and a cathode located on the organic light emitting layer. In the organic light emitting device, when a voltage is applied between the anode and the cathode, holes are injected from the anode into the organic light emitting layer, and electrons are injected from the cathode into the organic light emitting layer. The holes and electrons injected into the organic luminescent layer are recombined in the organic luminescent layer to generate an exciton. The exciton transitions from the excited state to the ground state and emits light. When the anode, the cathode, and the organic light emitting layer are brought into contact with moisture, oxygen, NOx, etc. in the air, the performance and lifetime of the anode, cathode, and organic light emitting layer are remarkably lowered.

The organic light emitting device can be manufactured as a thin film by itself, which can drastically reduce the thickness of the light source, and has low temperature rising tendency and low power driving capability. In addition, the organic light emitting device can function as a panel of a display device by using various kinds of organic light emitting materials capable of realizing various color lights, and is widely used for a backlight of a liquid crystal display device, various lighting devices, display devices and the like .

In recent years, techniques have been developed to increase the size of the organic light emitting device. However, as the size of the organic light emitting device increases, it is difficult to increase the size due to the difference in luminance between the center and the edge.

FIG. 1 is a diagram illustrating a mode in which a positive power source and a negative power source are supplied in a conventional organic light emitting device.

In the organic light emitting device 10, a positive power source is supplied to the electrode pad positioned at the left and right sides of the organic light emitting element 20, and a negative power is supplied to the electrode pad positioned at the upper and lower sides of the organic light emitting element 20.

However, the charge density is high around each edge and edge of the organic light emitting element 20, but as shown by the arrow, the charge density becomes lower toward the center portion due to electric resistance or the like. Therefore, in the organic light emitter 20, the edge portion having the highest density of positive and negative charges has the highest voltage and the highest luminance. In the center portion of the organic light emitter 20 having the lowest density of positive and negative charges, the lowest voltage and the lowest luminance are obtained. If such luminance unevenness occurs, it is difficult to emit a high luminance and the lifetime of the organic light emitting device is adversely affected.

2 is a view showing another conventional organic light emitting device.

The organic light emitting element 30 includes an auxiliary wiring 31 arranged on the anode or cathode side in a checkered pattern in order to mitigate the difference between the center and the edge luminance. The auxiliary wiring 31 may be made of, for example, silver (Ag).

However, even if the auxiliary wiring 31 is used, the resistance difference between the center and the edge can not be reduced. Therefore, there is a limit in reducing the luminance difference between the center and the edge. Further, there is a problem in that a process is added to provide the auxiliary wiring 31 and the material cost of the organic light emitting element 30 is increased.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an organic light emitting device capable of improving the unevenness of luminance in an organic light emitting device with a simple structure.

According to an aspect of the present invention, an organic light emitting device includes a substrate; A first electrode layer formed on the substrate and supplied with a first power; An organic light emitting layer on the first electrode layer; A second electrode layer formed on the organic light emitting layer and supplied with a second power supply having an opposite polarity to the first power supply; One or more conductors spaced apart from the second electrode layer and positioned adjacent to the second electrode layer and supplied with a third power supply having an opposite polarity to the second power supply; And a control unit.

The first power source and the third power source have the same polarity.

A protective cover spaced apart from the second electrode layer and positioned on the second electrode layer; And the conductor is exposed toward the second electrode layer through an opening formed in the protective cover.

A protective cover spaced apart from the second electrode layer and positioned on the second electrode layer; And the conductor is attached to the lower surface of the protective cover.

In addition, a predetermined space is included between the protective cover and the second electrode layer, and the predetermined space is filled with a high thermal conductive gas.

Also, the high thermal conductive gas may include at least one of air, helium, and hydrogen.

Further, the conductor is located on a central portion of the second electrode layer.

Further, a plurality of the conductors are arranged in a cross shape on the central portion of the second electrode layer.

Further, a plurality of the conductors are arranged on the central portion of the second electrode layer in a triangular or rectangular shape.

The conductor further includes a first conductor located on a central portion of the second electrode layer and a second conductor spaced apart around the periphery of the first conductor, Are different from each other.

Further, the first power source and the third power source are electrically connected to each other

Further, the conductor is connected to the voltage regulating means.

The voltage regulating means may be an OP AMP.

The conductive material may be at least one of zinc, tin, indium, cadmium, gallium, nickel, iron, cobalt, tungsten, titanium, chromium, molybdenum, gold, platinum, calcium, barium, magnesium, silver, copper, aluminum, indium tin oxide, indium Zinc oxide, or an alloy thereof.

The first electrode layer and the second electrode layer may be formed of at least one selected from the group consisting of zinc, tin, indium, cadmium, gallium, nickel, iron, cobalt, tungsten, titanium, chromium, molybdenum, gold, platinum, calcium, barium, Aluminum, indium tin oxide, indium zinc oxide, or an alloy thereof.

According to the present invention, it is possible to provide an organic light emitting device capable of improving luminance non-uniformity by forming an electric field in a portion where the luminance is reduced in the organic light emitting device.

FIG. 1 is a diagram illustrating a mode in which a positive power source and a negative power source are supplied in a conventional organic light emitting device.
2 is a view showing another conventional organic light emitting device.
FIG. 3 is a view showing a schematic structure of an organic light emitting device according to an embodiment of the present invention.
4 is a plan view showing the organic light emitting device of FIG.
FIG. 5 is a graph showing the difference in luminance between the center and the edge in the conventional organic light emitting device.
FIG. 6 is a graph showing a current difference between a center and an edge in a conventional organic light emitting device. Referring to FIG.
7 is a view showing a schematic structure of an organic light emitting device according to another embodiment of the present invention.
8A to 8D are views showing an embodiment in which conductors are arranged in the organic light emitting device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same reference numerals in the drawings denote like elements throughout the drawings.

FIG. 3 is a view showing a schematic structure of an organic light emitting device according to an embodiment of the present invention. 4 is a plan view showing the organic light emitting device of FIG. FIG. 5 is a graph showing the difference in luminance between the center and the edge in the conventional organic light emitting device. FIG. 6 is a graph showing a current difference between a center and an edge in a conventional organic light emitting device. Referring to FIG.

The organic light emitting element includes an anode and a cathode, and an organic light emitting layer between the anode and the cathode. When a voltage is applied between the anode and the cathode, holes are injected from the anode into the organic light emitting layer, and electrons are injected from the cathode into the organic light emitting layer. The holes and electrons injected into the organic luminescent layer are recombined in the organic luminescent layer to generate an exciton. The exciton transitions from the excited state to the ground state and emits light.

Such an organic light emitting device can be manufactured as a thin film and widely used for a light source, a backlight of a liquid crystal display device, various lighting devices, and a display device. However, although the charge density is high around each edge and edge of the organic light emitting element, the charge density is lowered due to electric resistance or the like toward the center, resulting in unevenness of luminance.

Referring to FIG. 5, in the organic light emitting device, the luminance decreases from the edge toward the center, and then tends to increase toward the edge. This luminance difference is caused by the difference of the current. Referring to FIG. 6, it can be seen that the current difference is considerably generated at the center and the edge of the organic light emitting device.

As described above, the difference in luminance between the center and the edge of the organic light emitting element is due to the fact that the electric current (charge density) at the center is lowered due to electrical resistance or the like. In this embodiment, the non-uniformity of the current at the center and the edge of the organic light emitting element is improved, so that the luminance difference can be mitigated.

3 and 4, the organic light emitting device 100 includes a substrate 110, a first electrode layer 120, an organic light emitting material 130, a second electrode layer 140, a protective cover 150, a conductor 160 ).

The substrate 110 may be a transparent substrate or an opaque substrate. In addition, the substrate 110 may be made of a flexible material having flexibility. In one example, the substrate 110 is made of a transparent glass substrate. The substrate 110 may have a polygonal shape, a circular shape, an elliptical shape, a star shape, an arbitrary curved shape, or the like.

A first electrode layer 120 is formed on the substrate 110. The first electrode layer 120 may be formed by depositing or applying a conductive material on the substrate 110. The first electrode layer 120 may include an opaque metal material such as zinc (Zn), tin (Sn), indium (In), cadmium (Cd), gallium (Ga), nickel (Ni) , Cobalt (Co), tungsten (W), titanium (Ti), chromium (Cr), molybdenum (Mo), gold (Au), platinum (Pt), calcium (Ca), barium (Ba) , Silver (Ag), copper (Cu), aluminum (Al), or an alloy thereof. The first electrode layer 120 may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). For example, the first electrode layer 120 may be made of ITO. A first power source 121 is supplied to the first electrode layer 120. In this embodiment, the first power source 121 may be a positive power source, and the first electrode layer 120 may be used as an anode electrode.

An organic light emitting material 130 is disposed on the first electrode layer 120. The organic light emitter 130 has an emissive layer that emits light as a result of recombination of electron-hole pairs. The light emitting layer may include a red light emitting material, a green light emitting material, or a blue light emitting material. The organic light emitting device 130 may include a hole injecting layer, a hole transporting layer, an electron transporting layer, and an electron injecting layer.

The hole-injecting layer may be formed of at least one selected from the group consisting of phthalocyanine copper complex (CuPc), m-MTDATA (4,4 ', 4 "tris (3-methylphenylphenylamino) triphenlamine can be used.

On the hole injection layer, a hole transport layer having a HOMO value of a level (± 5%) similar to that of the hole injection layer is formed. As the hole transport layer, TPD (N, N-dipheny] -N, N-bis (3-methylphenyl) -1,1- biphenyl- 1-naphtyl) -N-phenyl-amino] biphenyl] may be used.

On the hole transporting layer, a light emitting layer which emits light by the combination of electrons and holes is formed. Molecular-weight substances such as Alq3 (Tris- (8-hydroxyquinoline) aluminum) and DPVBi (4,4-bis (2,2-diphenylvinyl) -1,1- biphenyl), or PPV (p-phenylenevinylene) PPV (2-methoxy-5- (2-ethylhexyloxy) -1,4-phen-xylenvinylene) and PT (polythiophene).

Holes injected into the hole injecting layer can be injected into the light emitting layer through the hole transporting layer.

An electron transport layer for providing electrons to the light emitting layer is formed on the light emitting layer. The electron transport layer uses a material having a low LUMO (Lowest Unoccupied Molecular Orbital) value. As the electron transporting layer, any one of Alq3 (Tris- (8-hydroxyquinoline) aluminum) and Bebq2 (bis (benzoquinoline) berellium) may be used.

An electron injection layer is formed on the electron transporting layer. Electrons having a high energy through the electron injection layer are transferred to the light emitting layer through an electron transporting layer serving as a channel.

A second electrode layer 140 is formed on the organic light emitting layer 130. The second electrode layer 140 may be formed of an opaque metal material such as zinc (Zn), tin (Sn), indium (In), cadmium (Cd), gallium (Ga), nickel (Ni) , Cobalt (Co), tungsten (W), titanium (Ti), chromium (Cr), molybdenum (Mo), gold (Au), platinum (Pt), calcium (Ca), barium (Ba) , Silver (Ag), copper (Cu), aluminum (Al), or an alloy thereof. The second electrode layer 140 may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). For example, the second electrode layer 140 is made of aluminum. A second power source 141 having a polarity opposite to that of the first power source 121 is supplied to the second electrode layer 140. In this embodiment, the second power source 141 may be a negative power source, and the second electrode layer 140 may be used as a cathode electrode.

When the organic light emitting device emits light on one side, either the first electrode layer 120 or the second electrode layer 140 is formed of a transparent electrode. When the organic light emitting device emits light on both sides, the first electrode layer 120 And the second electrode layer 140 are both formed as transparent electrodes.

A protective cover 150 may be formed on the second electrode layer 140 so as to be spaced apart from the second electrode layer 140. The protective cover 150 covers the entirety of the second electrode layer 140 to prevent moisture and foreign substances from penetrating into the second electrode layer 140 and the like. The protective cover 150 may be formed of, for example, glass.

A sealing material 145 may be applied between the protective cover 150 and the laminate of the first electrode layer 120, the organic light emitting material 130, and the second electrode layer 140. The sealing material 145 may be applied along the periphery of the laminate using dispensing or the like. The sealing material 145 is applied so as to protrude from the upper surface of the second electrode layer 140 so that the protective cover 150 is spaced apart from the second electrode layer 140 at a predetermined interval.

The protective cover 150 is spaced apart from the second electrode layer 140 so that a predetermined space may be formed between the protective cover 150 and the second electrode layer 140. A high thermal conductive gas (that is, a gas having excellent thermal conductivity) is filled in the predetermined space. In order to keep the high thermal conductive gas in the predetermined space, an encapsulation process may be performed on the organic light emitting device so as to surround the protective cover and the entire substrate.

In this manner, by filling the high thermal conductive gas into the predetermined space formed between the second electrode layer and the protective cover, the resistance heat generated from the second electrode layer can be efficiently transferred through the protective cover in a noncontact heat transfer (for example, convective heat transfer) Emitting device. This can reduce the deterioration of the organic light-emitting device due to heat generation, thereby improving the lifetime of the organic light-emitting device.

Preferably, the high thermal conductive gas may comprise at least one of air, helium and hydrogen.

An opening 151 is formed in the protective cover 150 and the conductor 160 is seated on the seating portion 152 formed on the protective cover 150 and exposed to the second electrode layer 140 through the opening 151 have. The seating part 152 may form a step so that the conductor 160 can be seated.

The conductor 160 is spaced apart from the second electrode layer 140 and positioned adjacent to the second electrode layer 140. The conductor 160 is supplied with a third power source 161 having a polarity opposite to that of the second power source 141. Accordingly, the third power source 161 has the same polarity as the first power source 121. [ The third power source 161 may be electrically connected to the first power source 121. A power supply line for supplying the third power source 161 to the conductor 160 may be embedded in the protection cover 150 or may extend along the protection cover 150.

The conductor 160 may have a constant shape and volume. The conductor 160 may be formed of a metal material such as Zn, Sn, In, Cd, Ga, Ni, Fe, Co, ), Tungsten (W), titanium (Ti), chrome (Cr), molybdenum (Mo), gold (Au), platinum (Pt), calcium (Ca), barium (Ba), magnesium ), Copper (Cu), aluminum (Al), or an alloy thereof. In addition, the conductor 160 may be formed of, for example, ITO or IZO.

The conductor 160 is supplied with a power supply having a polarity opposite to that of the power supplied to the second electrode layer 140. For example, when negative power is supplied to the second electrode layer 140, a positive power source is supplied to the conductor 160.

In the second electrode layer 140, the electrons e are emitted through the electron injecting layer and the electron transporting layer of the organic light emitter 130, About 30% of the electrons meet the holes in the light emitting body and do not contribute to the light emission, and pass through the hole transporting layer and the hole injecting layer. In this embodiment, by locating the conductor 160 adjacent to the second electrode layer 140, it is possible to reduce loss of electrons that can not contribute to light emission.

The conductor 160 is charged in the opposite polarity to the second electrode layer 140 so that electrons escaping through the hole transport layer and the hole injection layer due to the electric field effect are confined to a portion adjacent to the conductor 160, Increase the probability of meeting and responding. Accordingly, the luminous efficiency of the organic light emitting diode can be improved at the portion where the conductor 160 is located.

Particularly, when the conductor 160 is positioned at the central portion where the brightness of the organic light emitting device is lowered, the luminance of the center portion can be improved. Although the conductor 160 is not a central portion of the organic light emitting element, it may be arbitrarily located at least one portion to improve brightness.

The conductor 160 may be connected to the voltage regulating means 170 to adjust the magnitude of the voltage supplied to the conductor 160. The voltage regulating means 170 may be, for example, an OP AMP.

7 is a view showing a schematic structure of an organic light emitting device according to another embodiment of the present invention. In Fig. 7, the same components as those in the embodiment of Fig. 3 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In this embodiment, no opening is formed in the protective cover 250, and the conductor 260 is attached to the lower surface of the protective cover 250. [ A second power source 141 supplied to the second electrode layer 140 and a third power source 261 having an opposite polarity are supplied to the conductor 260.

The conductor 260 may be connected to the voltage regulating means 270 to adjust the magnitude of the voltage supplied to the conductor 260. This voltage regulating means 270 may be, for example, an OP AMP.

8A to 8D are views showing an embodiment in which conductors are arranged in the organic light emitting device of the present invention.

Referring to FIG. 8A, the conductors 160 may be disposed at a plurality of positions spaced apart from each other in the longitudinal direction in the organic light emitting device. For example, the conductors 160 may be disposed at three centers in the center of the organic light emitting device. The conductor 160 includes a first conductor 160a positioned on a central portion of the organic light emitting element (or the second electrode layer), and a second conductor 160b and 160c spaced along the periphery of the first conductor 160a ). At this time, voltages supplied to the first conductor 160a and the second conductors 160b and 160c may be different from each other. This is because the voltage supplied to each of the conductors 160 can be controlled differently according to the luminance characteristics of the organic light emitting device so that a desired luminance characteristic can be exhibited.

Referring to FIG. 8B, the conductors 160 may be disposed in the center of the organic light emitting device, and may be arranged in a plurality of crosses. The conductor 160 includes a first conductor 160a positioned on a central portion of the organic light emitting device and second conductors 160b, 160c, 160d, and 160e spaced along the periphery of the first conductor 160a . Here, voltages supplied to the first conductor 160a and the second conductors 160b, 160c, 160d, and 160e may be different from each other.

Referring to FIG. 8C, the conductors 160 may be disposed in a plurality of triangular shapes at the center of the organic light emitting device.

Referring to FIG. 8D, the conductors 160 may be spaced apart in a rectangular shape at the center of the organic light emitting device.

As such, the conductor 160 can be freely arranged in an arbitrary form in a portion where the luminance is to be improved in the organic light emitting element. In addition, when a plurality of conductors 160 are disposed, the voltages supplied to the respective conductors 160 can be configured differently.

As described above, the conductor according to the embodiment of the present invention has a polarity different from that of the power supplied to the second electrode layer and is disposed on the second electrode layer, thereby improving the brightness of the portion where the conductor is disposed by the electric field effect . Accordingly, by disposing the conductor in the portion where the luminance is lowered in the organic light emitting element, uniformity of luminance can be improved by a simple method.

Further, since the conductors can be arranged in arbitrary positions and shapes in a portion where the luminance is to be improved in the organic light emitting device, even when the shape of the organic light emitting device is changed, the conductor can be disposed at a desired position to easily ensure uniformity of brightness . Further, when a plurality of conductors are arranged, a desired luminance characteristic can be realized by changing the voltages supplied to the respective conductors.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention will be.

100: Organic light emitting device
110: substrate
120: first electrode layer
121: First power
130: organic phosphor
140: Second electrode layer
141: Second power source
145: Seal material
150: protective cover
160: Conductor
161: Third power source
170: voltage regulating means

Claims (16)

In the organic light emitting device,
Board;
A first electrode layer formed on the substrate and supplied with a first power;
An organic light emitting layer on the first electrode layer;
A second electrode layer formed on the organic light emitting layer and supplied with a second power supply having an opposite polarity to the first power supply;
One or more conductors positioned at a central portion of the organic light emitting device and spaced apart from the second electrode layer to be adjacent to the second electrode layer and supplied with a third power supply having an opposite polarity to the second power supply;
And an organic light emitting layer. The method according to claim 1,
And the polarities of the first power source and the third power source are of the same polarity. The method according to claim 1,
A protective cover spaced apart from the second electrode layer and positioned on the second electrode layer;
Further comprising:
And the conductor is exposed toward the second electrode layer through an opening formed in the protective cover. The method according to claim 1,
A protective cover spaced apart from the second electrode layer and positioned on the second electrode layer;
Further comprising:
Wherein the conductor is attached to the lower surface of the protective cover. The method according to claim 3 or 4,
A predetermined space is included between the protective cover and the second electrode layer,
Wherein the predetermined space is filled with a high thermal conductive gas. 6. The method of claim 5,
Wherein the high thermal conductive gas comprises at least one of air, helium, and hydrogen. 5. The method according to any one of claims 1 to 4,
And the conductor is located on a central portion of the second electrode layer. delete delete 5. The method according to any one of claims 1 to 4,
Wherein the conductor comprises a first conductor located on a central portion of the second electrode layer and a second conductor spaced along a periphery of the first conductor,
Wherein voltages applied to the first conductor and the second conductor are different from each other. 5. The method according to any one of claims 1 to 4,
Wherein the first power source and the third power source are electrically connected to each other. 5. The method according to any one of claims 1 to 4,
Wherein the conductor is connected to a voltage regulating means. delete 5. The method according to any one of claims 1 to 4,
Wherein the conductor is selected from the group consisting of zinc, tin, indium, cadmium, gallium, nickel, iron, cobalt, tungsten, titanium, chromium, molybdenum, gold, platinum, calcium, barium, magnesium, silver, copper, aluminum, indium tin oxide, Or an alloy thereof. 5. The method according to any one of claims 1 to 4,
Wherein the first electrode layer and the second electrode layer are formed of at least one selected from the group consisting of zinc, tin, indium, cadmium, gallium, nickel, iron, cobalt, tungsten, titanium, chromium, molybdenum, gold, platinum, calcium, barium, magnesium, Indium tin oxide, indium zinc oxide, or an alloy thereof. Board;
A first electrode layer formed on the substrate and supplied with a first power;
An organic light emitting layer on the first electrode layer;
A second electrode layer formed on the organic light emitting layer and supplied with a second power supply having an opposite polarity to the first power supply;
One or more conductors spaced apart from the second electrode layer and positioned adjacent to the second electrode layer and supplied with a third power supply having an opposite polarity to the second power supply;
Lt; / RTI >
The conductor,
A first conductor located on a central portion of the second electrode layer, and a second conductor spaced apart from the first conductor.

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