Organic light emitting device and manufacturing method thereof

An organic light emitting device and a manufacturing method thereof are provided. The organic light emitting device includes a first display substrate, a second display substrate, and a first adhesive force improving member. The first display substrate includes a first substrate, a first electrode, organic light emitting patterns, a first spacer, and a second electrode. The first electrode is formed on an entire surface of the first substrate, and the organic light emitting patterns are disposed on the first electrode. The first spacer corresponds to the organic light emitting pattern and is disposed on the first electrode. The second electrode covers the organic light emitting patterns and the first spacer. The second display substrate includes a second substrate, and a first driving signal delivery part. The first adhesive force improving member electrically/physically couples the second electrode to the first driving signal delivery part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic light emitting device and a manufacturing method of the organic light emitting device.

2. Description of the Related Art

Recently, an information processing apparatus that capable of processing a large amount of data within a short time and a display device for displaying data processed by the information processing apparatus have been developed.

Generally, display devices may are classified into analog display devices and digital display devices. Cathode ray tubes (CRTs) is a representative the analog display device, and a liquid crystal display device (LCD), an organic light emitting device (OLED), and a plasma display panel (PDP) are representative the digital display devices

Recently, the digital display devices having a small volume and lightweight compared to analog display devices are widely used.

Furthermore, recently, technology development for OLEDs of digital display devices is under rapid development.

A related OLED displays an image using an organic light emitting layer interposed between a pair of electrodes. Also, to display a full color image using a related art organic light emitting layer, the related art OLED includes a switching transistor, a driving transistor, and a capacitor. Also, since two transistors, a capacitor, and organic light emitting elements are formed on the same substrate, a manufacturing method thereof is complicated, and an aperture ratio of the organic light emitting layer may reduce.

To solve these disadvantages, there has developed an OLED where a switching transistor, a driving transistor, and a capacitor are formed on one substrate, while organic light emitting elements are formed on the other substrate. In detail, the switching transistor, the driving transistor, and the capacitor are disposed on a lower substrate, while the organic light emitting elements are formed on an upper substrate facing the lower substrate.

In an organic light emitting device having the above-described construction, a drive signal is transferred from a conductor connected to a driving transistor of a lower substrate to an electrode of an organic light emitting element of an upper substrate, so that an image is displayed from the organic light emitting device.

However, an image generated from an OLED where elements are formed on two substrates, respectively, may be frequently interrupted by a factor such as temperature rise, impact, vibration, and humidity absorption. The reason an image is interrupted is that a conductor connected to a driving transistor of a lower substrate is separated from an electrode of an organic light emitting element of an upper substrate as an interval between the two substrates is widened.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an organic light emitting device and a manufacturing method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an organic light emitting device that prevents elements emitting light and formed on two substrates facing each other from being separated from one another when the substrates are deformed.

Another object of the present invention is to provide a method for manufacturing an organic light emitting device having the above-described construction.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an organic light emitting device including a first display substrate, a second display substrate, a first adhesive force improving member, a second adhesive force improving member, and a sealing member. The first display substrate includes a first substrate, a first electrode formed on an entire surface of the first substrate, an organic light emitting pattern disposed on the first electrode, a first spacer corresponding to the organic light emitting pattern and disposed on the first electrode, a second electrode covering the organic light emitting pattern and the first spacer, a second spacer disposed on the first electrode, and a connecting member covering the second spacer and connected to the first electrode. The second display substrate includes a second substrate facing the first substrate, a first driving signal delivery part disposed on the second substrate and facing the first spacer, and a second driving signal delivery part facing the second spacer. The first adhesive force improving member couples the second electrode to the first driving signal delivery part. The second adhesive force improving member couples the first electrode to the second driving signal delivery part. The sealing member seals the first and second display substrates.

In another aspect of the present invention, there is provided a method for manufacturing an organic light emitting device, the method including: manufacturing a first display substrate by forming a first electrode over an entire surface of a first substrate, forming a first spacer on the first electrode and a second spacer separated from the first spacer, forming organic light emitting patterns corresponding to the first spacer on the first electrode, forming a second electrode covering the organic light emitting pattern and the first spacer, forming a connecting member covering a second spacer and connected to the first electrode; manufacturing a second display substrate by forming a first driving signal delivering part facing the first spacer on a second substrate facing the first substrate, and forming a second driving signal delivering part facing the second spacer; bonding the second electrode and the first driving signal delivering part using a first adhesive force improving member, and bonding the first electrode and the second driving signal delivering part using a second adhesive force improving member; and sealing the first and second display substrates using a sealing member.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The present invention is not limited to the following embodiments but a person of ordinary skill in the art would realize the present invention in various other forms within the scope of the present invention. In the accompanying drawings, a first display substrate, a second display substrate, a first adhesive force improving member, a second adhesive force improving member, a sealing member, and other structures are exaggerated in size for clarity of the present invention. It will also be understood that when a first display substrate, a second display substrate, a first adhesive force improving member, a second adhesive force improving member, a sealing member, and other elements are referred to as being ‘on’ or ‘under’ a substrate, they may be directly ‘on’ or ‘under’ the substrate, or another first display substrate, second display substrate, first adhesive force improving member, second adhesive force improving member, sealing member, and other elements may be additionally formed on the substrate. Also, though terms like a first, a second, and a third are used to describe various regions and layers in various embodiments of the present invention, the regions and the layers are not limited to these terms. These terms are used only to tell one region or layer from another region or layer. Therefore, the terms like a first and a second may be selectively or exchangeably used for a first display substrate, a second display substrate, a first adhesive force improving member, a second adhesive force improving member, and other structures.

Organic Light Emitting Device

FIG. 1is a block diagram illustrating an organic light emitting device according to a first embodiment of the present invention.FIG. 2is a cross-sectional view ofFIG. 1.

Referring toFIG. 1, the organic light emitting device includes at least one switching transistor STR, a driving transistor DTR, a capacitor, an organic light emitting element EL, a data line DL, and a power line PW in order to display an image.

The data line DL and the gate line GL are insulated from each other by an insulating layer (not shown). For example, the gate line GL is disposed under the insulating layer, and the data line DL is disposed on the insulating layer. The gate line GL and the data line DL are disposed to substantially perpendicular to each other In a plan view. The power line PW is disposed in parallel to the data line DL.

The switching transistor STR includes a gate electrode G1, a channel layer C1, a source electrode S1, and a drain electrode D1.

The gate electrode G1is disposed under the insulating layer and branches off from the gate line GL. The channel layer C1is disposed on the insulating layer and formed at a position corresponding to the gate electrode G1. The source electrode S1is disposed on the insulating layer. The source electrode S1branches off from the data line DL. An end portion of the source electrode S1is electrically contacted to the channel layer C1. The drain electrode D1is disposed on the insulating layer and electrically contacted to the channel layer C1. The source electrode S1and the drain electrode D1are spaced apart from each other by a predetermined distance.

The driving transistor DTR includes a gate electrode G2, a channel layer C2, a source electrode S2, and a drain electrode D2.

The gate electrode G2is disposed under the insulating layer and electrically connected to the drain electrode D1of the switching transistor STR. The channel layer C1is disposed on the insulating layer and formed at a position corresponding to the gate electrode G2. The source electrode S2is disposed on the insulating layer. A first end portion of the source electrode S2is electrically contacted to the channel layer C2, and a second end portion opposite to the first end portion is electrically connected to the power line PW. A first end portion of the drain electrode D2is disposed on the channel layer C2. The first end portion of the drain electrode D2is spaced apart from the first end portion of the source electrode S2. A second end portion of the drain electrode D2is connected earth potentials.

A pair of electrodes of a capacitor is electrically connected to the drain electrode D1of the switching transistor STR and the drain electrode D2of the driving transistor DTR, respectively.

The organic light emitting element EL is electrically connected to the source electrode S2of the driving transistor DTR.

Referring toFIGS. 1 and 2, elements of the organic light emitting device600descried with reference toFIG. 1are formed on a first display substrate100and a second display substrate200, respectively. Meanwhile, the organic light emitting device600includes a first adhesive force improving member300and a second adhesive force improving member400for improving adhesive force between elements distributed on the first and second display substrates100and200.

The elements formed on the first display substrate100are described below.

Referring toFIGS. 1 and 2, the organic light emitting element EL is formed on the first display substrate100. The switching transistor STR, the driving transistor DRT, a capacitor C, the data line DL, the gate line GL, and the power line PW are formed on the second display substrate200as illustrated inFIG. 1.

The organic light emitting element EL formed on the first display substrate100includes a first substrate10, a first electrode20, organic light emitting patterns30, a first spacer40, a second electrode50, a second spacer60, and a connecting member70.

The first substrate10includes a transparent substrate, for example. In detail, the first substrate10may be a glass substrate having a plate shape. One face of the first substrate10that faces the second display substrate200is defined as a first face11. The other face of the first substrate10that faces the first face11is defined as a second face12.

The first electrode20is disposed on the first face of the first substrate10. In the present embodiment, the first electrode20includes a transparent conductive material. Examples of a material that may be used as the first electrode20include Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), and amorphous Indium Tin Oxide (a-ITO), etc. In the present embodiment, the first electrode20is formed over an entire area of the first face11of the first substrate10.

FIG. 3is a detailed cross-sectional view of the organic light emitting patterns ofFIG. 2.

Referring toFIG. 3, the organic light emitting patterns30are disposed on the first electrode20. The plurality of organic light emitting patterns30may be disposed on the first electrode20in a matrix shape. To dispose the organic light emitting patterns30in a matrix shape, a partition wall (not shown) having a lattice shape may be disposed on the first electrode20.

The organic light emitting patterns30may include a hole injection layer (HIL), a hole transport layer (HTL), an organic electroluminescent layer (OEL), an electron transport layer (ETL), and an electron injection layer (EIL). The organic light emitting patterns30according to the present embodiment may be formed by a vacuum deposition method, for example.

Referring again toFIG. 2, the first spacer40may be disposed on the first electrode20. In detail, the first spacer includes an insulating material, and is disposed at an adjacent position to each organic light emitting pattern30.

The second electrode50is disposed on the organic light emitting patterns30and the first spacer40located at a position close to the organic light emitting patterns30. In the present embodiment, the second electrode50includes a conductor having a relatively small work function compared to that of the first electrode20. In the present embodiment, examples of a material that may be used as the second electrode50include aluminum and an aluminum alloy, etc. The second spacer60is disposed on the first electrode20. The second spacer60is disposed at a position spaced apart from the first spacer40. In the present embodiment, heights of the first and second spacers40and60measured from the first electrode20are substantially the same.

The connecting member70covers the second spacer60and the connecting member70is electrically connected to the first electrode20. In the present embodiment, examples of a material that may be used as the connecting member70include aluminum and an aluminum alloy, etc.

Elements disposed on the second display substrate200are described below.

Referring again toFIG. 2, the switching transistor STR, the driving transistor DRT, a capacitor C, the data line DL, the gate line GL, and the power line PW are formed on the second display substrate200as described in detail with reference toFIG. 1.

A first driving signal delivery part210, which is a portion of the source electrode S2of the driving transistor DTR disposed on the second display substrate200is disposed to face the first spacer40. A second driving signal delivery part220, which is a portion of the power line PW, is disposed to face the second spacer60.

In detail, the first driving signal delivery part210, which is a portion of the source electrode S2of the driving transistor DTR is electrically connected to the second electrode covering the first spacer40. The second driving signal delivery part220, which is a portion of the power line PW, is electrically connected to the connecting member70covering the second spacer60.

An operation of the organic light emitting device600including elements distributed over the first and second display substrates100and200will be briefly described with reference toFIGS. 1 and 2.

First, a driving signal for displaying an image is applied via the data line DL, so that a drive signal is applied to the source electrode S1of the switching transistor STR. Subsequently, a turn-on signal for turning on the switching transistor STR is applied to the gate line GL, so that the driving signal applied to the source electrode S1is provided to the drain electrode D1via the channel layer C1where a channel is formed.

The driving signal provided to the drain electrode D1is applied to the gate electrode G2of the driving transistor DTR to form a channel at the channel layer C2of the driving transistor DTR and simultaneously charges the capacitor C.

Meanwhile, since a second driving signal delivery part220, which is a portion of the power line PW, is connected to the conductive connecting member70covering the second spacer60, power is applied to the first electrode20of the first display substrate100from the second display substrate200via the power line PW.

Therefore, in the case that a channel is formed in the channel layer C2of the driving transistor DTR, a forward current is applied to the organic light emitting element EL, so that light is emitted from the organic light emitting element EL.

The first adhesive force improving member300not only electrically connects the second electrode50of the first display substrate100to the first driving signal delivery part210of the second display substrate200, but also solidly couples the second electrode50to the first driving signal delivery part210physically and chemically. In detail, the first adhesive force improving member300may be molten to couple to the second electrode50and the first driving signal delivery part210. Particularly, the first adhesive force improving member300prevents the second electrode50and the first driving signal delivery part210from being separated from each other even when an interval between the first and second display substrates100and200is widened due to twisting, impact, vibration, and thermal expansion caused by temperature rise.

In the present embodiment, the first adhesive force improving member300may be formed of metal of a low melting point molten at a temperature range of about 300° C. to about 450° C. Examples of metal of a low melting point that may be used as the first adhesive force improving member300include In, Zn, Pb, Ca, Mg, and Sn, etc.

Referring again toFIG. 2, the first adhesive force improving member300may entirely cover the second electrode50. The second adhesive force improving member400not only electrically connect the connecting member70of the first display substrate100to the second driving signal delivery part220of the second display substrate200, but also solidly couples them physically and chemically. In detail, the second adhesive force improving member400is molten to electrically connect the connecting member70to the second driving signal delivery part220. The second adhesive force improving member400prevents the connecting member70and the second driving signal delivery part220from being separated from each other even when an interval between the first and second display substrates100and200is widened due to twisting, impact, vibration, and thermal expansion caused by temperature rise.

In the present embodiment, the second adhesive force improving member400may be formed of metal of a low melting point molten at a temperature range of about 300° C. to about 450° C. Examples of metal of a low melting point that may be used as the second adhesive force improving member400include In, Zn, Pb, Ca, Mg, and Sn, etc.

Referring again toFIG. 2, the second adhesive force improving member300may entirely cover the connecting member70.

A sealing member500is interposed between the first display substrate100and the second display substrate200to prevent harmful materials such as oxygen, moisture, and hydrogen from penetrating between the first and second display substrates100and200.

A porous member capable of adsorbing harmful materials using plurality of holes may be mixed into the sealing member500according to the present embodiment.

FIG. 4is a cross-sectional view of an organic light emitting device according to a second embodiment of the present invention. An organic light emitting device according to the second embodiment of the present invention has substantially the same construction of the above-described organic light emitting device according to the first embodiment except the first and second adhesive force improving members. Therefore, same names and reference numerals are used for the same construction as that of the first embodiment.

Referring toFIGS. 1 and 4, the organic light emitting device600includes a first display substrate100including an organic light emitting element EL, and a second display substrate200including a switching transistor STR, a driving transistor DTR, a capacitor, a data line DL, a gate line GL, and a power line PW.

Also, the organic light emitting device600further includes a first adhesive force improving member310and a second adhesive force improving member410.

In the present embodiment, the first adhesive force improving member310may be disposed between the second electrode50and a first driving signal delivery part210. Also, the second adhesive force improving member410may be locally disposed between a connecting member70and a second driving signal delivery part220.

In detail, the first adhesive force improving member310may be locally disposed on an upper end of the protruding second electrode50that corresponds to a first spacer40. The second adhesive force improving member410may be locally disposed on an upper end of the connecting member70that corresponds to the second spacer60.

FIG. 5is a cross-sectional view of an organic light emitting device according to a third embodiment of the present invention. The organic light emitting device according to the third embodiment of the present invention has substantially the same construction of the above-described organic light emitting device according to the second embodiment except the first and second adhesive force improving members. Therefore, same names and reference numerals are used for the same construction as that of the second embodiment.

Referring toFIGS. 1 and 5, the organic light emitting device600includes a first display substrate100including an organic light emitting element EL, and a second display substrate200including a switching transistor STR, a driving transistor DTR, a capacitor, a data line DL, a gate line GL, and a power line PW.

Also, the organic light emitting device600further includes a first adhesive force improving member320and a second adhesive force improving member420.

In the present embodiment, the first adhesive force improving member320may be locally disposed on an upper surface of a first driving signal delivery part210, which is a portion of a source electrode S2of the drain transistor DTR disposed on the second display substrate200. Unlike this, the first adhesive force improving member320may completely cover the surface of the first driving signal delivery part210. Also, the second adhesive force improving member420is disposed to face a second spacer60, and locally disposed on an upper surface of the second driving signal delivery part220, which is a portion of the power line PW. Unlike this, the second adhesive force improving member420may completely cover the surface of the second driving signal delivery part220.

Method for Manufacturing Organic Light Emitting Device

FIG. 6is a flowchart illustrating a method for manufacturing an organic light emitting device according to a fourth embodiment of the present invention, andFIGS. 7 to 10are cross-sectional views illustrating a process for manufacturing a first display substrate.

Referring toFIG. 6, a first display substrate100is manufactured in order to manufacture an organic light emitting device in S10. Of course, a second display substrate in S20, which will be described later, may be manufactured prior to the first display substrate.

Referring toFIGS. 6 and 7, a first electrode20is formed on an entire surface of the first substrate10. In the present embodiment, the first substrate10may be a transparent glass substrate, for example. To form the first electrode20, a transparent conductive layer (not shown) is formed on an entire surface of the first substrate10. The transparent conductive layer may be formed on the first substrate10using chemical vapor deposition (CVD) or sputtering. After formed on the first substrate10, the transparent conductive layer is patterned using photolithography to form the transparent and conductive first electrode20on the first substrate10.

Referring toFIG. 8, after the first electrode20is formed on the first substrate10, a first spacer40and a second spacer60separated from the first spacer40are formed on the first electrode20.

To form the first spacer40and the second spacer60, a thin insulating layer (not shown) covering the first electrode20is formed on the first substrate10. In the present embodiment, the insulating layer may include an organic material including photoresist.

The thin insulating layer covering the first electrode is patterned using photolithography including an exposure process and a developing process to simultaneously form the first spacer40and the second spacer60protruding from the first substrate10on the first substrate10.

In the present embodiment, since the first spacer40and the second spacer60are formed by patterning the insulating layer, they have substantially the same height. In the present embodiment, the first spacer40is formed at every position corresponding to a plurality of organic light emitting patterns, which will be described below.

Referring toFIG. 9, after the first and second spacers40and60are formed on the first electrode20, organic light emitting patterns30are formed on the first electrode20.

In the present embodiment, an EIL is formed on the first electrode20, an ETL is formed on the EIL, an organic electroluminescent layer OEL is formed on the ETL, an HTL is formed on the OEL, and a HIL is formed on the HTL, so that the organic light emitting patterns30are manufactured. In the present embodiment, the first electrode20provides electrons to the EIL.

Referring toFIG. 10, after the organic light emitting patterns30is manufactured, a metal layer (not shown) having a small work function compared to that of the first electrode10is formed over an entire surface of the first substrate10to cover the organic light emitting patterns30. In the present embodiment, the metal layer is formed using sputtering. Examples of a material that is used as the metal layer include aluminum and an aluminum alloy.

Subsequently, the metal layer is etched using photolithography to form a second electrode50and a connecting member70on the first substrate10. In the present embodiment, the second electrode50is insulated from the first electrode20, and covers the organic light emitting patterns30and the first spacer40. The connecting member70covers the second spacer40and is electrically connected to the first electrode20. Through the above process, the first display substrate100is manufactured. In the present embodiment, the second electrode50and the connecting member70are electrically insulated when they are etched using photolithography.

FIG. 11is a cross-sectional view explaining manufacturing of a second display substrate according to a fourth embodiment of the present invention.

Referring toFIGS. 1,6, and11, the switching transistor STR, the driving transistor DTR, the capacitor, the data line DL, the gate line GL, and the power line PW are formed on the second substrate205in S20as described with reference toFIG. 1.

A first driving signal delivery part210, which is a portion of the source electrode S1of the driving transistor DTR, is formed on the second substrate205to face the first spacer40. A second driving signal delivery part220, which is a portion of the power line PW, is disposed to face the second spacer60. Through the above process, the second display substrate200is manufactured.

FIG. 12is a cross-sectional view explaining elements of a first display substrate are electrically connected to elements of a second display substrate according to a fourth embodiment of the present invention.

Referring toFIGS. 1,6, and12, a first adhesive force improving member300is formed on the second electrode50, and a second adhesive force improving member400is formed on the connecting member70to electrically connect and physically couple the second electrode50and the connecting member70, which are the elements of the first display substrate, to the first driving signal delivery part210and the second driving signal delivery part220, which are the elements of the second display substrate in S30.

In the present embodiment, each of the first and second adhesive force improving members300and400includes metal of a low melting point that is molten at a temperature range of about 300-450° C. In the present embodiment, examples of a material that may be used as the first and second adhesive force improving members300and400include In, Zn, Pb, Ca, Mg, and Sn.

In the present embodiment, the first and second adhesive force improving members300and400may be selectively formed on the second electrode50and the connecting member70through evaporation using a shadow mask, for example.

In the present embodiment, the first and second adhesive force improving members300and400may be formed over entire surfaces of the second electrode50and the connecting member70of the first display substrate100, for example. Unlike this, the first and second adhesive force improving members300and400may be selectively formed only on a surface of the second electrode50of the first display substrate100, and portions of the connecting member70that contact the first and second driving signal delivery parts210and220. Unlike this, the first and second adhesive force improving members300and400may be formed on the first and second driving signal delivery parts210and220of the second display substrate200.

After the first and second adhesive force improving members300and400are formed on the second electrode50and the connecting member70, a sealing member500is disposed on an edge of the second display substrate200. Subsequently, the first adhesive force improving member300of the first display substrate100contacts the first driving signal delivery part210of the second display substrate200, and the second adhesive force improving member300of the first display substrate100contacts the second driving signal delivery part210of the second display substrate200.

Subsequently, the first and second display substrates100and200are heated to a temperature range of about 300-450° C., so that the first and second adhesive force improving members300and400disposed on the second electrode50and the connecting member70of the first display substrate100are molten. Through the above process, the second electrode50of the first display substrate100is electrically connected and physically coupled to the first driving signal delivery part210of the second display substrate200. The connecting member70of the first display substrate100is electrically connected and physically coupled to the second driving signal delivery part220of the second display substrate200.

As described above in detail, two display substrates are not separated from each other when elements of an organic light emitting device are distributed on the two display substrates, so that interruption of an image is prevented.

It will be apparent to those skilled in the art that various modifications and variations may be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.