Transparent electrode and organic light emitting diode device including the transparent electrode and method of manufacturing the same

Disclosed are a transparent electrode including a first light-transmission layer, a metal layer, and a second light-transmission layer sequentially formed, an organic light emitting device including the transparent electrode, and a method of manufacturing the same. The second light-transmission layer includes a conductive oxide and a metal catalyst.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on 30 Dec. 2010 and there duly assigned Serial No. 10-2010-0139431.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure is related to a transparent electrode, an organic light emitting diode device including the transparent electrode, and a method of manufacturing the same.

2. Description of the Related Art

Recently, an organic light emitting diode device (OLED device) has been paid attention to as a display device and an illumination device.

An organic light emitting diode device in general includes two electrodes and an emission layer disposed therebetween and emits light when electrons injected from one electrode are combined with holes injected from the other electrode and thus, forms excitons and releases energy.

Herein, at least either of the two electrodes may be a transparent electrode that may externally emit light.

The transparent electrode may include a conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), and the like. The conductive oxide becomes crystalline during the process and thus, may form a pin hole in a predetermined region of the transparent electrode. The pin hole may play a role of being a passage for a chemical solution such as an etchant and the like flown inside the transparent electrode during the subsequent process, resulting in display defects.

SUMMARY OF THE INVENTION

An exemplary aspect of the present invention provides a transparent electrode that prevents display defects.

Another aspect of the present invention provides an organic light emitting device including the transparent electrode.

Yet another aspect of the present invention provides a method of manufacturing an organic light emitting device.

According to one embodiment, a transparent electrode is provided that includes a first light-transmission layer, a metal layer formed on the first light-transmission layer, and a second light-transmission layer formed on the metal layer. The second light-transmission layer includes a conductive oxide and a metal catalyst.

The second light-transmission layer may include two conductive oxide layers including the conductive oxide and a metal catalyst layer positioned between the two conductive oxide layers and including the metal catalyst.

The second light-transmission layer may be a single layer including the conductive oxide and the metal catalyst.

The metal layer may be thinner than the first and second light-transmission layers.

The metal layer may include silver (Ag), aluminum (Al), molybdenum (Mo), or an alloy thereof.

The first and second light-transmission layers may include indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

According to another embodiment, an organic light emitting device is provided that includes a substrate, a first electrode disposed on the substrate, an emission layer disposed on the first electrode, and a second electrode disposed on the emission layer. The first electrode may include a first light-transmission layer, a metal layer formed on the first light-transmission layer, and a second light-transmission layer formed on the metal layer. The second light-transmission layer may include a conductive oxide and a metal catalyst.

The second light-transmission layer may include two conductive oxide layers including the conductive oxide and a metal catalyst layer positioned between the two conductive oxide layers and including the metal catalyst.

The second light-transmission layer may be a single layer including the conductive oxide and the metal catalyst.

The metal layer may include silver (Ag), aluminum (Al), molybdenum (Mo), or alloys thereof.

The first and second light-transmission layers may include indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The organic light emitting device may further include a thin film transistor electrically connected to the first electrode. The thin film transistor may include a semiconductor layer including a source region, a channel region, and a drain region, a gate electrode overlapped with the channel region of the semiconductor layer, and a source electrode and a drain electrode respectively connected to the source region and the drain region of the semiconductor layer. The gate electrode may further include a first light-transmission layer, a metal layer, and a second light-transmission layer formed at the same layer as the first electrode. The second light-transmission layer may include a conductive oxide and a metal catalyst.

The organic light emitting device may further include a gate insulating layer disposed between the semiconductor layer and the gate electrode. The gate insulating layer may contact the first electrode.

The second electrode may be a reflective electrode.

According to yet another embodiment, a method of manufacturing an organic light emitting device is provided that includes forming a semiconductor layer on a substrate, forming a gate insulating layer on the semiconductor layer, sequentially laminating and patterning a first light-transmission layer, a metal layer, and a second light-transmission layer including a conductive oxide and a metal catalyst on the gate insulating layer to form a gate electrode and a first electrode, forming a source region, a channel region, and a drain region in the semiconductor layer, forming a source electrode and a drain electrode respectively connected to the source region and the drain region of the semiconductor layer, forming an emission layer on the first electrode, and forming a second electrode on the emission layer.

The second light-transmission layer may be formed by sequentially laminating a first conductive oxide layer, a metal catalyst layer, and a second conductive oxide layer.

The second light-transmission layer may be formed into a single layer by sputtering the conductive oxide and the metal catalyst together

Accordingly, the transparent electrode made of a conductive oxide may have no pin hole and thus, prevent display defects.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of this disclosure are shown. This disclosure may, however, be embodied in many different forms and is not construed as limited to the exemplary embodiments set forth herein.

Hereinafter, illustrated is a transparent electrode according to one embodiment referring toFIG. 1.

FIG. 1is a cross-sectional view showing a transparent electrode according to one embodiment.

Referring toFIG. 1, a transparent electrode190according to one embodiment includes a lower light-transmission layer191, a metal layer192, and an upper light-transmission layer193.

The lower light-transmission layer191may be formed of a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The metal layer192may be made of a thin metal and thus, has semi-transmission characteristic. For example, a metal with low resistance such as silver (Ag), aluminum (Al), molybdenum (Mo), or alloys thereof may be made to be about 20 Å to about 250 Å-thick. The metal layer192may improve conductivity of the transparent electrode190and thus, prevent a signal delay.

The upper light-transmission layer193may include two conductive oxide layers193pand193rand a metal catalyst layer193qpositioned between the two conductive oxide layers193pand93r.

The conductive oxide layers193pand193rmay be formed of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The metal catalyst layer193qis positioned between the conductive oxide layers193pand193rand may be formed of metal particles. The metal particle may include, for example, nickel (Ni), palladium (Pd), titanium (Ti), silver (Ag), gold (Au), aluminum (Al), tin (Sn), antimony (Sb), copper (Cu), cobalt (Co), molybdenum (Mo), tritium (Tr), ruthenium (Ru), rhodium (Rh), cadmium (Cd), platinum (Pt), or a combination thereof.

The upper light-transmission layer193includes a metal catalyst layer193qbetween conductive oxide layers193pand193rto prevent corrosion of the metal layer192due to a chemical solution such as an etchant during the process. In particular, a conductive oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO) for the lower and upper light-transmission layers191and193becomes crystalline during the process and thus, forms a plurality of grain boundaries in which a plurality of pin holes are generally generated. The pin holes may play a role of passing a chemical solution such as an etchant during the subsequent process. Thus, the chemical solution may contact with the lower layer and corrode a metal.

In the present embodiment, the transparent electrode190includes a metal catalyst layer193qto prevent generation of a pin hole, resultantly preventing defects due to the pin holes during the process.

Hereinbefore, a metal catalyst is formed into a metal catalyst layer193qas an upper light-transmission layer193between conductive oxide layers193pand193r. However, the upper light-transmission layer193may be formed into a single layer including a conductive oxide and a metal catalyst. When the upper light-transmission layer193is formed as a single layer, it may be prepared by co-sputtering a conductive oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO) and a metal catalyst.

The metal catalyst may be included sufficiently enough to remove the pin holes, for example, in a concentration of about 1×1013atoms/□ to about 1×1015atoms/□.

The lower light-transmission layer191, the metal layer192, and the upper light-transmission layer193are sequentially laminated into a transparent electrode that entirely transmits a light. Herein, the metal layer192may be thinner than the lower and upper light-transmission layers191and193. For example, the lower and upper light-transmission layers191and193may have a thickness ranging from about 50 Å to about 1000 Å. The metal layer192may have a thickness ranging from about 20 Å to about 250 Å.

Hereinafter, a transparent electrode according to another embodiment is illustrated referring toFIG. 2.

FIG. 2is a cross-sectional view showing a transparent electrode according to another embodiment.

Referring toFIG. 2, the transparent electrode190according to the present embodiment includes a lower light-transmission layer191a, a metal layer192a, a lower light-transmission layer191b, a metal layer192b, and an upper light-transmission layer193.

The lower light-transmission layers191aand191bmay be formed of a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The metal layers192aand192bmay be thin enough and thus, have semi-transmission characteristic. For example, a metal with low resistance such as silver (Ag), aluminum (Al), molybdenum (Mo), or alloys thereof may be formed to be about 20 Å to about 250 Å thick. The metal layer192may improve conductivity of the transparent electrode190and thus, prevent a signal delay.

According to the embodiment, the lower light-transmission layers191aand191band the metal layers192aand192bare twice laminated unlike the aforementioned embodiment. When the lower light-transmission layers191aand191band the metal layers192aand192bare more than once laminated, the laminated product may be easily patterned.

In addition, the lower light-transmission layers191aand191band the metal layers192aand192bmay be more than 2 times laminated.

The upper light-transmission layer193may include two conductive oxide layers193pand193rand a metal catalyst layer193qdisposed between the two conductive oxide layers193pand193ras aforementioned.

The conductive oxide layers193pand193rmay be formed of, for example, indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The metal catalyst layer193qmay be positioned between the conductive oxide layers193pand193rand formed of metal particles. The metal particle may include, for example, nickel (Ni), palladium (Pd), titanium (Ti), silver (Ag), gold (Au), aluminum (Al), tin (Sn), antimony (Sb), copper (Cu), cobalt (Co), molybdenum (Mo), tritium (Tr), ruthenium (Ru), rhodium (Rh), cadmium (Cd), platinum (Pt), or a combination thereof.

Since the upper light-transmission layer193includes a metal catalyst layer193qbetween the conductive oxide layers193pand193ras aforementioned, it may prevent corrosion of the metal layer192due to a chemical solution such as an etchant during the process.

Hereinafter, illustrated is an organic light emitting device including the transparent electrode referring toFIG. 3.FIG. 3is a cross-sectional view showing one pixel in an organic light emitting device according to one embodiment.

According to one embodiment, an organic light emitting device may include a switching transistor region (Qs) including a switching thin film transistor, a driving transistor region (Qd) including a driving thin film transistor, and a light emitting region (LD) including an organic light emitting diode (OLED) in each pixel.

The switching thin film transistor has a control terminal, an input terminal, and an output terminal. The control terminal is connected to a gate line (not shown). The input terminal is connected to a data line (not shown). The output terminal is connected to a driving thin film transistor. The switching thin film transistor responds to a scan signal applied to the gate line and transfers the data signal to the driving thin film transistor.

The driving thin film transistor also has a control terminal, an input terminal, and an output terminal. The control terminal is connected to the switching thin film transistor. The input terminal is connected to a driving voltage line (not shown). The output terminal is connected to an organic light emitting diode (OLED). The driving thin film transistor may shed an output current (ILD) with a different size depending on a voltage between the control and output terminals.

The organic light emitting diode (OLED) includes an anode connected to the output terminal of the driving thin film transistor and a cathode connected to a common voltage. The organic light emitting diode (OLED) emits a light depending on strength of the output current (ILD) of the driving thin film transistor and displays an image.

Referring toFIG. 3, a buffer layer111is disposed on a transparent substrate110such as a glass substrate, a polymer layer, silicon wafer, or the like.

The buffer layer111may be made of, for example, silicon oxide, silicon nitride, or the like. It may play a role of preventing moisture or impurity generated from the transparent substrate110from moving up and controlling a heat delivery speed during the crystallization of the following semiconductor layer and thus, increasing its crystalline.

On the buffer layer111, each semiconductor layer154aand154bis respectively formed on in the switching transistor region Qs and the driving transistor region Qd. The semiconductor layers154aand154bmay include channel regions154a1and154b1and source regions154a2and154b2and drain regions154a3and154b3at both sides of the channel regions154a1and154b1.

The semiconductor layers154aand154bmay include a polycrystalline semiconductor. The source regions154a2and154b2and the drain regions154a3and154b3are doped with an n-type or p-type impurity.

Then, a gate insulating layer140is disposed on the semiconductor layers154aand154b.

On the gate insulating layer140, a pixel electrode190is formed in the light emitting region LD. Each gate electrode120aand120bis respectively formed in the switching transistor region Qs and the driving transistor region Qd.

The pixel electrode190and the gate electrodes120aand120bmay have a stacking structure having a plurality of layers.

The stacking structure of the pixel electrode190and the gate electrodes120aand120bare illustrated referring toFIGS. 4A to 4C.

FIG. 4Ais a cross-sectional view enlarging the pixel electrode190of the organic light emitting device inFIG. 3.FIG. 4Bis a cross-sectional view enlarging the gate electrode120aof the switching transistor region (Qs) in the organic light emitting device inFIG. 3.FIG. 4Cis a cross-sectional view enlarging the gate electrode120bof the driving transistor region (Qd) in the organic light emitting device inFIG. 3.

First of all, referring toFIG. 4A, the pixel electrode190may include a lower light-transmission layer191, a metal layer192, and an upper light-transmission layer193.

The lower light-transmission layer191may be made of a transparent conductive oxide. The transparent conductive oxide may be made of, for example, indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), gallium indium zinc oxide (GIZO), zinc oxide (ZnO), or a combination thereof.

The metal layer192may be made of a thin metal and have semi-transmission characteristic. For example, a metal with low resistance such as silver (Ag), aluminum (Al), molybdenum (Mo), or alloys thereof may be made to be about 20 Å to about 250 Å thick. The metal layer192may improve conductivity of the pixel electrode190and prevent a signal delay.

The upper light-transmission layer193may include two conductive oxide layers193pand193rand a metal catalyst layer193qpositioned between the two conductive oxide layers193pand193r.

Since the upper light-transmission layer193includes a metal catalyst layer193qbetween the conductive oxide layers193pand193r, it may prevent corrosion of the metal layer192due to a chemical solution such as an etchant.

For example, when the lower light-transmission layer191, the metal layer192, and the upper light-transmission layer193are sequentially laminated, a plurality of pin holes are generated in a conductive oxide when the lower and upper light-transmission layers191and193are formed. Herein, when the laminated lower light-transmission layer191, metal layer192, and upper light-transmission layer193are patterned by using an etchant etching all of them or an etchant etching each layer, the etching solution is flown in through the pin holes and corrodes the metal layer192, resulting in display defects.

According to the embodiment, an upper light-transmission layer193includes a metal catalyst layer193qand thus, decreases the number of pin holes and prevents an etchant from flowing into the metal layer192.

Referring toFIGS. 4B and 4C, gate electrodes120aand120bare laminated through the same process as the pixel electrode190and patterned by using the same mask and thus, have the same stacking structure as the pixel electrode190. Accordingly, the gate electrodes120aand120bmay include lower light-transmission layers121aand121b, metal layers122aand122b, and upper light-transmission layers123aand123b. The specific illustration is the same as aforementioned. The upper light-transmission layer123aincludes two conductive oxide layers123paand123raand a metal catalyst layer123qapositioned between the two conductive oxide layers123paand123ra. The upper light-transmission layer123bincludes two conductive oxide layers123pband123rband a metal catalyst layer123qbpositioned between the two conductive oxide layers123pband123rb.

Next, an insulation layer160is formed to cover gate electrodes124aand124band a gate insulating layer140in the region except for the light emitting region LD. The insulation layer160may include a lower insulation layer160pof an inorganic material and an upper insulation layer160qmade of an organic material. Either of the lower and upper insulation layer insulation layers160pand160qmay be omitted.

The insulation layer160may have a plurality of contact holes exposing source regions154a2and154b2and drain regions154a3and154b3of semiconductor layers154aand154bbut may be removed in the light emitting region LD thereof.

On the insulation layer160, each source electrode173aand173band each drain electrode175aand175bare respectively formed in the switching transistor region Qs and the driving transistor region Qd.

The source electrode173aand the drain electrode175ain the switching transistor region (Qs) are respectively connected to the source region154a2and the drain region154a3of the semiconductor layer154athrough a contact hole. The source electrode173band the drain electrode175bin the driving transistor region Qd are respectively connected to the source region154b2and the drain region154b3of the semiconductor layer154bthrough a contact hole.

Then, a partition361is formed on the whole of the substrate including source electrodes173aand173band drain electrodes175aand175b. The partition361has an opening exposing a pixel electrode190in the light emitting region. LD.

Then, an organic emission layer370is formed on the pixel electrode190in the light emitting region LD.

The organic emission layer370may be formed of an organic material expressing a light such as red, green, blue, and the like and a white light by combining them. Then, an emitting auxiliary layer (not shown) may be formed on at least either of lower and upper organic emission layers370. The light emitting auxiliary layer may be a hole injection layer HIL, a hole transport layer HTL, an electron injection layer EIL, and/or an electron transport layer ETL.

On the partition361and the organic emission layer370, formed is a common electrode270. The common electrode270may be made of a metal with a high reflectivity and may be a reflective electrode.

In the aforementioned organic light emitting device, either of the pixel electrode190and the common electrode270may be an anode. The other one may be a cathode. The anode and cathode as a pair may shed a current into an organic emission layer370.

In addition, the pixel electrode190and the common electrode270may have a micro cavity structure. The microcavity structure may amplify a light with a particular wavelength region due to reinforcement interference, as a light repetitively reflects between a reflection layer with an optical length apart from a light and a (semi)transparent layer. According to the embodiment, a common electrode270may play a role of a reflective layer, while the pixel electrode190plays a role of a (semi)transparent layer. The optical length may be adjusted by changing a distance between the common electrode270and the pixel electrode190per each pixel.

The common electrode270may modify light emitting characteristic of an organic emission layer370. A light around a wavelength corresponding to the resonance wavelength region of microcavity among the modified lights is reinforced through the pixel electrode190and emits toward the transparent substrate110, while lights with other wavelength regions may be suppressed.

According to the embodiment, an organic light emitting device includes a pixel electrode190as a transparent electrode and a common electrode270as a reflective electrode and thus, has a bottom emission structure in which a light emitted from the emission layer370emits toward a substrate110.

Hereinafter, illustrated is a method of manufacturing the aforementioned organic light emitting device referring toFIGS. 5 to 14along withFIG. 3.

FIGS. 5 to 14are a cross-sectional view sequentially showing a method of manufacturing the organic light emitting device inFIG. 3.

First of all, referring toFIG. 5, a buffer layer111is formed on a transparent substrate110by a chemical vapor deposition (CVD) method.

Next, referring toFIG. 6, an amorphous silicon layer is deposited on the buffer layer111by a chemical vapor deposition (CVD) or PVD method and crystallized. The crystallization may be performed in a method of, for example, excimer laser annealing (ELA), sequential lateral solidification (SLS), metal induced crystallization (MIC), metal induced lateral crystallization (MILC), super grain silicon (SGS), or the like.

The crystallized semiconductor layer is patterned to form semiconductor layers154aand154b.

Then, referring toFIG. 7, a gate insulating layer140is formed on the whole of the substrate including semiconductor layers154aand154b.

Referring toFIG. 8, a transparent conductive layer120g, a metal layer120h, a transparent conductive layer120i, a metal catalyst layer120j, and a transparent conductive layer120kare sequentially laminated on the gate insulating layer140.

Referring toFIG. 9, the transparent conductive layer120g, the metal layer120h, the transparent conductive layer120i, the metal catalyst layer120j, and the transparent conductive layer120kare etched all together by using an etchant to form gate electrodes120aand120band a pixel electrode190. However, the transparent conductive layer120g, the metal layer120h, the transparent conductive layer120i, the metal catalyst layer120j, and the transparent conductive layer120kmay be etched by using each etchant.

In addition, the gate electrodes120aand120band the pixel electrode190may be formed by respectively laminating a transparent conductive layer120i, a metal catalyst layer120j, and a transparent conductive layer120kor by co-sputtering a conductive oxide and a metal catalyst as a single transparent layer containing the metal catalyst.

Next, the gate electrodes120aand120bare used as a mask to inject n-type or p-type impurity into the semiconductor layers154aand154band form source regions154a2and154b2and drain regions154a3and154b3doped with an impurity and channel regions154a1and154b1doped with no impurity.

Referring toFIG. 10, an inorganic material is deposited on the whole of the substrate including the gate electrodes120aand120bto form a lower insulation layer160p. Then, an organic material is coated on the lower insulation layer160pto form an upper insulation layer160q.

Referring toFIG. 11, the upper insulation layer160qis patterned. Then, the lower insulation layer160pand the gate insulating layer140are patterned to form a plurality of contact holes exposing the source regions154a2and154b2and drain regions154a3and154b3and simultaneously, exposing the pixel electrode190.

Referring toFIG. 12, a metal layer is laminated on the upper insulation layer160qand then, patterned to form source electrodes173aand173bconnected to the source regions154a2and154b2and drain electrodes175aand175bconnected to the drain regions154a3and154b3.

Referring toFIG. 13, a partition361is formed by coating an organic layer on the whole of the substrate and patterning it.

InFIG. 14, an organic emission layer370is disposed on the pixel electrode190.

Referring toFIG. 3, a common electrode270is formed on the organic emission layer370.

Hereinafter, the embodiments are illustrated in more detail with reference to examples. These examples, however, should not in any sense be interpreted as limiting the scope of the present invention.

EXAMPLE

Fabricated was a thin film transistor according to the aforementioned embodiment. Then, a pixel electrode was formed thereon by respectively laminating ITO/Ag/ITO/Ni/ITO to respectively have a thickness or a concentration of 70 Å, 150 Å, 150 Å, 1×1015atoms/cm2, and 150 Å, respectively and then, patterned using a nitric acid-based etching solution to fabricate a transparent electrode.

Comparative Example

A thin film transistor and a transparent electrode were formed according to the same method as Example except for laminating 70 Å, 150 Å, and 300 Å thick ITO/Ag/ITO to form a pixel electrode.

The thin film transistor and the transparent electrode fabricated according to Example and Comparative Example was evaluated regarding display characteristic.

FIG. 15Ais a photograph showing the pattern of the thin film transistor and the transparent electrode according to Example.FIG. 15Bis a photograph showing the pattern of the thin film transistor and the transparent electrode Comparative Example.

Referring toFIGS. 15A and 15B, the transparent electrode according to Example had remarkably less stains due to damage on a metal layer (Ag) than the transparent electrode according to Comparative Example.

Accordingly, the transparent electrode of Example had improved display characteristic.