KR20100128794A - Organic light emitting display device and method for fabricating the same - Google Patents

Abstract

PURPOSE: An organic light emitting display device and a fabricating method thereof are provided to prevent the voltage drop according to the increase of the sheet resistance by reducing the resistance of a second electrode by contacting an auxiliary electrode on the top of a bank insulation layer and the second electrode. CONSTITUTION: A first electrode(132) is formed on the fixed region of the light emission region and non-emitting area on a substrate(110). A bank insulating layer(138) is formed in the non-emitting area of the substrate. An auxiliary electrode(150) is formed on the top of the bank insulation layer of the non-emitting area.

Description

Organic Light Emitting Display Device and Method for fabricating the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, to an organic light emitting display device and a method of manufacturing the same, which can prevent an increase in power consumption and luminance unevenness of the organic light emitting display device.

Video display devices that realize various information as screens are the core technologies of the information and communication era, and are developing in a direction of thinner, lighter, portable and high performance. With the development of the information society in recent years, various forms of display devices have increased, and flat displays such as liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD), and field emission display (FED) There is an active research on the device. Among them, an organic light emitting display device that displays an image by controlling an emission amount of an organic light emitting layer as a flat panel display device that can reduce weight and volume, which is a disadvantage of a cathode ray tube (CRT), has been in the spotlight.

An organic light emitting display device is a self-luminous device using a thin light emitting layer between electrodes, and has an advantage of thinning like a paper. In an active matrix organic light emitting display device (AMOLED), pixels composed of three color (R, G, B) sub-pixels are arranged in a matrix to display an image. Each sub pixel includes an organic light emitting diode and a cell driver for independently driving the organic light emitting diode. The cell driver includes at least two thin film transistors and a storage capacitor to control the amount of current supplied to the organic light emitting display according to the data signal to control the brightness of the organic light emitting display.

The conventional organic light emitting device includes a second electrode, an organic light emitting layer, and a first electrode, and in the case of top emission, forms a second electrode formed of a translucent or transparent conductive layer on the light emitting surface side. The second electrode toward the light emitting surface is formed on the entire surface of the lower material layers. The area of the second electrode increases as the large surface increases, and accordingly, the resistance value further increases to generate a voltage drop (IR drop). In this case, power consumption increases due to an increase in voltage drop due to an increase in resistance of the second electrode, resulting in uneven brightness of the organic light emitting display device, thereby decreasing reliability.

An object of the present invention is to provide an organic light emitting display device and a method of manufacturing the same, which can prevent an increase in power consumption and luminance unevenness of the organic light emitting display device.

A method of manufacturing an organic light emitting display device according to the present invention includes forming a first electrode on a predetermined area of the light emitting area and the non-light emitting area on a substrate defined as a light emitting area and a non-light emitting area; Forming a bank insulating layer in the non-emitting region of the substrate to expose a first electrode, forming an auxiliary electrode on an upper surface of the bank insulating layer of the non-emitting region, and forming the substrate on which the auxiliary electrode is formed Forming an organic light emitting layer in the light emitting region and the non-light emitting region of, forming a second electrode in the light emitting region and the non-light emitting region of the substrate on which the organic light emitting layer is formed, and irradiating a laser to the auxiliary electrode And removing the organic emission layer formed on the upper portion and contacting the auxiliary electrode and the second electrode.

Here, the laser is irradiated to the organic light emitting layer of the upper surface of the auxiliary electrode.

The wavelength range of the laser is 500 nm to 650 nm.

The auxiliary electrode is formed of silver, copper, gold, aluminum, magnesium, neodymium, alloys thereof, or a stack thereof.

A method of manufacturing an organic light emitting display device includes forming a driving transistor in the non-light emitting region of the substrate before forming the first electrode, and exposing a predetermined region of the driving transistor to the entire surface of the substrate. The method further includes forming a planarization film.

In this case, the auxiliary electrode is formed of a conductive material used in forming the driving transistor.

The bank insulating layer is formed of polyimide.

In this case, the auxiliary electrode is formed such that the width of the auxiliary electrode is smaller than the width of the bank insulating layer.

The organic light emitting display device according to the present invention includes a first electrode electrically connected to a driving transistor formed in the non-light emitting area of a substrate defined as a light emitting area and a non-light emitting area, and the first electrode of the light emitting area is exposed. A bank insulating layer formed in the non-light emitting region of the substrate to separate sub-pixel units, an auxiliary electrode formed on an upper surface of the bank insulating layer of the non-light emitting region, and an organic layer formed on the first electrode of the light emitting region And a second electrode formed on the substrate including a light emitting layer and the auxiliary electrode and the organic light emitting layer.

According to the present invention, the auxiliary electrode on the bank insulating layer is brought into contact with the second electrode to lower the resistance of the second electrode, thereby preventing a voltage drop caused by an increase in sheet resistance and preventing an increase in power consumption of the organic light emitting display device.

In addition, the luminance unevenness of the large area organic light emitting display device can be prevented to improve the reliability of the organic light emitting display device.

Hereinafter, an organic light emitting display device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

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

The organic light emitting display device according to the present invention includes a plurality of sub pixels, and one sub pixel includes a sub pixel driver formed on a substrate 110 defined as a light emitting area and a non-light emitting area, an organic light emitting device, A bank insulating layer 138 defining a sub pixel and an auxiliary electrode 150 formed on the bank insulating layer 138 are included.

The sub pixel driver includes a plurality of signal lines, thin film transistors, and insulating layers, and the sub pixel driver formed in each sub pixel mainly includes a switching transistor (not shown), a driving transistor 120, and a storage capacitor 160. do. The switching transistor supplies a data signal from the data line in response to the scan signal of the gate line, and the driving transistor 120 controls the amount of current flowing through the organic light emitting element in response to the data signal from the switching transistor. The storage capacitor 160 serves to allow a constant current to flow through the driving transistor 120 even when the switching transistor is turned off.

The driving transistor 120 overlaps the channel portion of the semiconductor layer 122 with the semiconductor layer 122 formed on the buffer layer 112 of the non-light emitting region of the substrate 110 and the gate insulating layer 114 interposed therebetween. The formed gate electrode 124 is included. In addition, the driving transistor 120 includes contact holes formed in the interlayer insulating layer 116 and the gate insulating layer 114 in the source and drain regions in which the impurity ions are injected into the semiconductor layer 122 at both sides of the gate electrode 124. It further includes a source electrode 126 and a drain electrode 127 contacted through.

In this case, the lower electrode of the capacitor 160 is made of the same material as the semiconductor layer 122, and the upper electrode is made of the same material as the gate electrode 124. Although not shown, the lower electrode of the capacitor 160 may be made of the same material as the gate electrode, and the upper electrode may be made of the same material as the source electrode 126 and the drain electrode 127.

The driving transistor 120 is electrically connected to the first electrode 132 through a contact hole 119 formed in the planarization layer 118 to apply an electric field to the organic light emitting diode.

The organic light emitting device emits red, green, and blue light according to the flow of current to display predetermined image information. The organic light emitting device displays the first electrode 132, the second electrode 136, which is the opposite electrode, and the gap between them. The organic light emitting layer 134 is disposed to emit light. The first electrode 132 and the second electrode 136 are insulated from each other, and light is emitted by applying voltages of different polarities to the organic light emitting layer 134.

The first electrode 132 is formed on the planarization layer 118 to be electrically connected to the drain electrode 127 of the driving transistor 120 through the contact hole 119 formed in the planarization layer 118. In this case, the first electrode 132 may be formed of Cr, Al, AlNd, Mo, Cu, W, Au, Ni, Ag, or the like, and may be formed of an alloy or an oxide thereof. Alternatively, the light emitting color of the organic light emitting layer 134 may be turned upward by the reflective layer by forming a multilayer of ITO / reflective layer / ITO. The first electrode 132 is formed so as not to be connected to the first electrode 132 of an adjacent sub pixel by a predetermined distance from the boundary of the sub pixel.

The organic emission layer 134 is a layer in which light is emitted while the axtone formed by combining holes and electrons injected from the first electrode 132 and the second electrode 136 falls to the ground state. The organic light emitting layer 134 may include a hole injection layer (HIL), a hole transporting layer (HTL), an emission layer (EL), an electron transporting layer (ETL), and an electron injection layer (HTL). electron injection layer (EIL). In this case, the organic light emitting layer 134 extends from the sidewall of the bank insulating layer 138 to be formed in the light emitting region other than the non-light emitting region in which the driving transistor 120 is formed, and is formed on the substrate 110 of the light emitting region.

The second electrode 136 is formed of a transparent conductive layer so that light emitted from the organic light emitting layer 134 can come out of the device. As the transparent conductive layer, indium tin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), or these It is formed by the combination of. The second electrode 136 is formed on the entire surface of the substrate 110 in a plate shape.

The organic light emitting diode formed as described above is separated into sub pixel units by the bank insulating layer 138, and red, green, and blue light may be emitted in sub pixel units to represent an image.

Meanwhile, the bank insulating layer 138 also insulates the second electrode 136 of the organic light emitting diode and other wirings or elements formed under the organic light emitting diode from interfering with each other. To this end, the bank insulating layer 138 covers the first electrode 132 on the driving transistor 120 in the non-light emitting region and exposes the first electrode 132 of the light emitting region to expose the non-light emitting region of the substrate 110. Is formed.

As the material of the bank insulating layer 138, an organic material or an inorganic material may be used. Examples of the organic material may include polyimide and the like, and the inorganic material may include a silicon nitride film or a silicon oxide film. When the bank insulating layer 138 is formed using a silicon nitride film or a silicon oxide film, a peeling phenomenon may occur in which the bank insulating layer 138 is lifted from the planarization film 118 in a subsequent process of forming the auxiliary electrode 150. have. Therefore, it is more preferable to use polyimide as the bank insulating layer 138 in order to prevent deterioration of the organic light emitting device such as the occurrence of peeling phenomenon.

An auxiliary electrode 150 is formed between the bank insulating layer 138 and the second electrode 136 to lower the sheet resistance of the second electrode 136.

The auxiliary electrode 150 is formed on the top surface of the bank insulating layer 138 to be electrically connected to the second electrode 136. The auxiliary electrode 150 may be formed using various conductive materials used for wiring of the sub pixel driver. Examples of the auxiliary electrode 150 include silver (Ag), copper (Cu), gold (AU), aluminum (Al), and magnesium (Mg), which have lower electrical resistance than the second electrode 136 and have high electrical conductivity. , Neodymium (Nd), alloys thereof, or laminations thereof.

At this time, the thickness of the auxiliary electrode 150 is 1000 kPa ~ 3000 kPa. As the width of the auxiliary electrode 150 is wider, the resistance of the second electrode 136 may be lowered, but the width of the auxiliary electrode 150 is smaller than the width of the bank insulating layer 138. The auxiliary electrode 150 is formed to be narrower than the width of the bank insulating layer 138 in order to prevent a decrease in the aperture ratio by not affecting the light emitting area even if a margin is errored.

As such, when the auxiliary electrode 150 that is electrically connected to the second electrode 136 is formed below the second electrode 136, the surface resistance of the second electrode 136 is lowered to thereby lower the voltage of the second electrode 136. The occurrence of a drop can be suppressed. In addition, it is possible to effectively suppress the luminance unevenness caused by the voltage drop of the second electrode 136. Therefore, the organic light emitting display device according to the present invention can be driven with a low driving voltage and can improve the reliability by making the luminance uniform.

On the other hand, although the organic light emitting display of the top emission is shown in the drawing, the organic light emitting display of the bottom emission may be implemented by changing the materials of the first electrode and the second electrode.

Hereinafter, a method of manufacturing the organic light emitting display device illustrated in FIG. 1 will be described with reference to FIGS. 2A to 2F.

Referring to FIG. 2A, a method of manufacturing an organic light emitting display device according to an exemplary embodiment of the present invention may include a substrate on which a driving transistor 120 formed in sub pixel units and a planarization film 118 covering the driving transistor 120 are formed. Prepare 110. In this case, the substrate 110 is defined as a light emitting area and a non-light emitting area, and the driving transistor 120 is formed in the non-light emitting area of the substrate 110. The storage capacitor 160 is formed at the side of the driving transistor 120 to allow a constant current to flow through the driving transistor 120. Although not shown, a switching transistor serving as a switch in addition to the driving transistor 120 and a plurality of wirings (not shown) for supplying power and driving signals to the device may be further formed on the substrate 110.

Specifically, the semiconductor layer is formed by patterning the polycrystalline silicon film in an island shape on the substrate 110 in the non-light emitting region by photo and etching processes. After the gate insulating film and the metal film are sequentially stacked on the entire surface including the semiconductor layer, the metal film is patterned by a photo and etching process to form a gate electrode at an overlapping position corresponding to the central portion of the semiconductor layer.

Next, a source-drain region is formed in the semiconductor layer using the gate electrode as a mask, a channel region in which impurity ions are not implanted, and a source electrode and a drain electrode respectively connected to the source-drain region are formed. As shown in FIG. 1, the driving transistor 120 is formed on the substrate 110 in sub pixel units.

Next, a planarization film 118 having a contact hole 119 exposing the drain electrode of the driving transistor 120 is formed on the substrate 110. As the planarization layer 118, an inorganic material such as a silicon nitride layer, a silicon oxide layer, or a laminated layer of a silicon oxide layer / silicon nitride layer may be used.

Referring to FIG. 2B, a first electrode 132 electrically connected to the drain electrode of the driving transistor 120 exposed through the contact hole 119 is formed on the planarization layer 118. The first electrode 132 may be formed of Cr, Al, AlNd, Mo, Cu, W, Au, Ni, Ag, or the like by sputtering or the like, and may include an alloy, an oxide thereof, or a multilayer of ITO / reflective film / ITO. It may also be formed as a multilayer.

Referring to FIG. 2C, a bank insulating layer 138 that separates the organic light emitting diodes for each sub pixel unit is formed.

Specifically, the bank insulating layer 138 is applied to the non-light emitting region of the substrate 110 on which the driving transistor 120 is formed by applying an insulating material to the entire surface of the substrate 110 on which the first electrode 132 is formed and then selectively removing the insulating material. To form. In this case, an organic material or an inorganic material may be used as the bank insulating layer 138, and polyimide may be used as the organic material, and a silicon nitride film or a silicon oxide film may be used as the inorganic material. On the other hand, it is preferable to use polyimide as the bank insulating layer 138 in order to prevent the peeling phenomenon that the bank insulating layer 138 is lifted from the planarization film 118 in a subsequent process.

Referring to FIG. 2D, the auxiliary electrode 150 is formed on the bank insulating layer 138.

Specifically, the conductive material is deposited on the entire surface of the substrate 110 including the bank insulating layer 138 by a deposition method such as sputtering, and then selectively removed so that the conductive material remains only on the upper surface of the bank insulating layer 138. 150 is formed.

As the conductive material constituting the auxiliary electrode 150, various conductive materials used for wiring of the sub-pixel driver may be used. For example, the conductive material has a low electrical resistance and high electrical conductivity compared to the second electrode to be formed in a subsequent process. Conductive materials can be used. Specifically, the auxiliary electrode 150 is formed using silver (Ag), copper (Cu), gold (AU), aluminum (Al), magnesium (Mg), neodymium (Nd), alloys thereof, or a stack thereof. do.

At this time, the thickness of the auxiliary electrode 150 is 1000 kPa ~ 3000 kPa. As the width of the auxiliary electrode 150 is wider, the resistance of the second electrode 136 may be lowered, but the width of the auxiliary electrode 150 is smaller than the width of the bank insulating layer 138. The formation of the auxiliary electrode 150 to be narrower than the width of the bank insulating layer 138 is taken into consideration in order to prevent a decrease in the aperture ratio by not affecting the light emitting area even if an error occurs in the margin.

On the other hand, if the auxiliary electrode is formed after the organic light emitting layer is formed, the material forming the auxiliary electrode is filled in the transparent portion of the mask used for forming the auxiliary electrode there is a problem that the mask can no longer be used and disposed of. However, since the auxiliary electrode 150 is formed after the bank insulating layer 138 forming process before forming the organic light emitting layer 134 to be formed in a subsequent process, the mask can be used continuously without the aforementioned problem. This can reduce the cost of the process.

Referring to FIG. 2E, the organic emission layer 134 and the second electrode 136 are sequentially stacked on the entire surface of the substrate 110 in the emission area and the non-emission area.

Specifically, the organic light emitting layer laminated with the organic material through a deposition method such as thermal deposition on the auxiliary electrode 150, the sidewall of the bank insulating layer 138, and the first electrode 132 exposed by the bank insulating layer 138. 132 is formed. The organic light emitting layer 132 includes a hole injection layer (HIL), a hole transporting layer (HTL), an emission layer (EL), an electron transporting layer (ETL), and an electron injection layer (HTL). electron injection layer (EIL). Here, the light emitting layer is separated by the bank insulating layer 138 in sub pixel units, and is formed to emit red, green, and blue light in the sub pixel units.

Subsequently, after the transparent conductive layer is deposited on the organic light emitting layer 134, the second electrode 136 is formed through a photolithography process and an etching process using a mask. Indium Tin Oxide (ITO), Tin Oxide (TO), Indium Zinc Oxide (IZO), Indium Tin Zinc Oxide (ITZO), or a transparent conductive layer Combination is used.

On the other hand, although the organic light emitting display of the top emission is shown in the drawing, the organic light emitting display of the bottom emission can be manufactured by changing the materials of the first electrode and the second electrode.

Referring to FIG. 2F, the organic light emitting layer 134 formed on the auxiliary electrode 150 is removed to electrically connect the auxiliary electrode 150 and the second electrode 136.

Specifically, the organic light emitting layer 134 is removed by irradiating a laser to the organic light emitting layer 134 formed on the auxiliary electrode 150 on the upper surface of the bank insulating layer 138, and the auxiliary electrode is melted by melting the second electrode 136. The 150 and the second electrode 136 are electrically connected to each other.

In this case, when the laser is irradiated with a short wavelength of less than 500nm, a large amount of foreign substances such as splashing of the thin film due to strong energy may occur, and may affect the bank insulation layer formed under the auxiliary electrode. When the laser is irradiated with a long wavelength of more than 650 nm, the energy is weak and the organic light emitting layer cannot be completely removed. Therefore, the organic light emitting layer 134 is completely removed so that the front surface of the auxiliary electrode 150 is in contact with the second electrode 136 and the laser is not affected in the bank insulating layer 138 under the auxiliary electrode 150. The wavelength range of is 500nm ~ 650nm.

As a specific experimental example, the surface resistance of the organic light emitting diode including the auxiliary electrode (AlNd; 2000 Hz) / organic light emitting layer (1000 Hz) / second electrode (Al, 10 mA / Ag, 150 Hz) before laser irradiation was 7.8 Ω, and the laser irradiation was performed. The surface resistance after this was 0.3 Ω. At this time, the wavelength range of the laser was 532nm, it was confirmed that there is no effect on the film quality of the bank insulating layer under the auxiliary electrode. As described above, according to the present invention, by providing the auxiliary electrode 150 electrically connected to the second electrode 136 on the bank insulating layer 138 in the non-light emitting area, the surface resistance of the second electrode 136 may be lowered.

As a result, the driving voltage of the driving transistor 120 may be prevented from increasing, thereby reducing power consumption. In addition, since the voltage drop can be prevented by compensating the surface resistance component of the second electrode 136, the luminance can be improved.

The above-described techniques represent presently preferred embodiments, and the present invention is not limited to the above-described embodiments and the accompanying drawings. Modifications and other uses of the embodiments will be apparent to those skilled in the art, and such changes and other uses are defined by the scope of the claims contained within or appended to the spirit of the invention.

1 is a cross-sectional view illustrating an organic light emitting display device according to the present invention.

2A through 2F are cross-sectional views illustrating a method of manufacturing the organic light emitting display device illustrated in FIG. 1.

<< Explanation of symbols for main part of drawing >>

110: substrate 118: planarization film

120: driving transistor 132: first electrode

134: organic light emitting layer 136: second electrode

138: bank insulating layer 150: auxiliary electrode

Claims (10)

Forming a first electrode on a predetermined area of the light emitting area and the non-light emitting area on a substrate defined as a light emitting area and a non-light emitting area; Forming a bank insulating layer on the non-light emitting area of the substrate to expose the first electrode of the light emitting area; Forming an auxiliary electrode on an upper surface of the bank insulating layer in the non-light emitting region; Forming an organic emission layer on the emission area and the non-emission area of the substrate on which the auxiliary electrode is formed; Forming a second electrode in the light emitting region and the non-light emitting region of the substrate on which the organic light emitting layer is formed; And Irradiating a laser to remove the organic light emitting layer formed on the auxiliary electrode, and contacting the auxiliary electrode with the second electrode. The method of claim 1, wherein the laser is irradiated to the organic light emitting layer on an upper surface of the auxiliary electrode. The method of claim 1, wherein the wavelength range of the laser is 500 nm to 650 nm. The method of claim 1, wherein the auxiliary electrode is formed of silver, copper, gold, aluminum, magnesium, neodymium, an alloy thereof, or a stack thereof. The method of claim 1, further comprising: forming a driving transistor in the non-light emitting region of the substrate before forming the first electrode; And forming a planarization film on the entire surface of the substrate to expose a predetermined region of the driving transistor. The method of claim 5, wherein the auxiliary electrode is formed of a conductive material used in forming the driving transistor. The method of claim 1, wherein the bank insulating layer is formed of polyimide. The method of claim 1, wherein the auxiliary electrode is formed such that a width of the auxiliary electrode is smaller than a width of the bank insulating layer. A first electrode electrically connected to a driving transistor formed in the non-light emitting area of the substrate defined as a light emitting area and a non-light emitting area; A bank insulating layer formed in the non-light emitting area of the substrate to expose the first electrode of the light emitting area to separate sub pixel units; An auxiliary electrode formed on an upper surface of the bank insulating layer in the non-light emitting region; An organic emission layer formed on the first electrode of the emission region; And And a second electrode formed on the substrate including the auxiliary electrode and the organic light emitting layer. The method of claim 9, wherein the width of the auxiliary electrode is smaller than the width of the bank insulating layer, The auxiliary electrode is formed of silver, copper, gold, aluminum, magnesium, neodymium, alloys thereof, or a stack thereof. The bank insulating layer is formed of polyimide.

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