Organic light emitting display device and method of fabricating the same

The present disclosure relates to an organic light emitting display device including a substrate having an outer part and a display part, a driving thin film transistor on each of a plurality of pixel regions within the display part of the substrate, a pixel electrode on each pixel region of the display part, an organic light emitting unit on each pixel region of the display part to emit light, a common electrode on the organic light emitting unit and a bank layer to apply a signal to the organic light emitting layer, and a first passivation layer, an organic insulating layer and a second passivation layer on the outer part and the display part, wherein the first passivation layer and the second passivation layer are removed from the outermost region of the outer part, so that the substrate is exposed to the outside.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

This specification relates to an organic light emitting display device and a fabricating method thereof, and more particularly, to an organic light emitting display device capable of preventing an occurrence of deterioration or defect due to permeation of air or moisture through cracks formed on a passivation layer, and a fabricating method thereof.

2. Background of the Disclosure

In recent time, various types of flat panel display devices capable of reducing weights and volumes, which are disadvantages of a cathode ray tube, are being developed. Examples of the flat panel display device include a liquid crystal display (LCD) device, a field emission display device, a plasma display panel, an organic light emitting display device, and the like.

Among those flat panel display devices, the plasma display device is focused on as a display device, which is light, thin, short and small and the most advantageous for providing a large-scaled screen, by virtue of simplified structure and fabricating processes. However, the plasma display device also has disadvantages in view of low luminous efficiency and brightness and high power consumption. On the other hand, the LCD device has disadvantages in view of being difficult to implement a large screen due to the use of a semiconductor process and causing high power consumption due to a backlight unit. Also, the LCD device exhibits a great optical loss and a narrow viewing angle due to optical elements, such as a polarizing filter, a prism sheet, a diffusion plate and the like.

On the contrary, light emitting display devices are classified into an inorganic light emitting display device and an organic light emitting display device according to a material of a light emitting layer. The organic light emitting display device is a self-light emitting device, which has great advantages in the aspects of fast response speed, high luminous efficiency, high brightness, and a large viewing angle. The inorganic light emitting display device causes high power consumption and is unable to obtain high brightness, as compared with the organic light emitting display device. Also, the inorganic light emitting display device cannot emit light with various colors of red (R), green (G) and blue (B). On the other hand, the organic light emitting display device is actively being studied by virtue of several advantages, such as being able to be driven by a low DC voltage, which is several tens of volts, having a fast response speed, providing high brightness, and emitting various colors of R, G and B.

Meanwhile, a flexible display device using a flexible substrate, such as a plastic substrate, has been proposed for portability and convenience in use. However, when the flexible substrate is applied to the organic light emitting display device, impurities or foreign materials, such as moisture or air may easily permeate through an upper substrate of the organic light emitting display device because the upper substrate of the display device is also formed of a flexible protection film or the like. Due to the permeation of the impurities such as moisture or air, a defective organic light emitting display device is fabricated and a lifespan of the device is reduced.

SUMMARY OF THE DISCLOSURE

Therefore, to obviate those drawbacks of the related art, an aspect of the detailed description is to provide an organic light emitting display device capable of preventing permeation of moisture, through a crack, which is generated on a passivation layer during cutting of a mother substrate due to non-formation of the passivation layer between adjacent panel regions of a plurality of panel regions of the mother substrate, and a fabricating method thereof.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided an organic light emitting display device including a substrate having an outer part and a display part, a driving thin film transistor formed on each of a plurality of pixel regions within the display part of the substrate, a pixel electrode formed on each pixel region of the display part, an organic light emitting unit formed on each pixel region of the display part, the organic light emitting unit emitting light, a common electrode formed on the organic light emitting unit and a bank layer to apply a signal to the organic light emitting layer, and a first passivation layer, an organic insulating layer and a second passivation layer formed on the outer part and the display part, wherein the first passivation layer and the second passivation layer are removed from the outermost region of the outer part, so that the substrate is exposed to the outside.

The first and second passivation layers may be made of an inorganic material, and the substrate may be a flexible substrate made of polyimide

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided a method for fabricating an organic light emitting display device including providing a mother substrate having a plurality of panel regions, attaching a substrate having a display part and an outer part onto each panel region of the mother substrate, forming an organic light emitting structure of the display part of the substrate, forming a first passivation layer on the display part of the substrate and a partial region of the outer part, forming an organic layer on the first passivation layer, forming a second passivation layer on the display part on the organic layer and a partial region of the outer part, dividing the mother substrate into a plurality of panel regions by cutting the mother substrate exposed to the outside between the adjacent panel regions of the mother substrate, and separating the mother substrate from the substrate.

The forming of the organic light emitting structure may include forming a thin film transistor on each pixel, forming a first electrode on each pixel, forming an organic light emitting unit on the first electrode, the organic light emitting unit emitting light, and forming a second electrode on the organic light emitting unit.

In accordance with the present disclosure, when a plurality of display panels are formed on a large-scaled mother substrate, various electrodes and light emitting layers may be formed on a flexible plastic substrate, without forming a passivation layer on a region between the adjacent display panels. This may prevent a production of cracks on the passivation layer during a cutting process when individual organic light emitting display devices are separated by cutting the mother substrate with a plurality of panel regions. Therefore, a defective organic light emitting display device, which may be caused due to permeation of moisture or foreign materials into the organic light emitting display device along into cracks produced on the passivation layer, can be prevented.

DETAILED DESCRIPTION OF THE DISCLOSURE

In an organic light emitting display device according to the present disclosure, upon forming a plurality of display panels on a large mother substrate, various electrodes and light emitting layers may be formed on a flexible plastic substrate, without forming a passivation layer on a region between the adjacent display panels. This may prevent a production of cracks on the passivation layer during a cutting process of cutting the mother substrate, which may result in prevention of permeation of moisture or foreign materials through the cracks.

FIG. 1is a view of a structure of an organic light emitting display device in accordance with the present disclosure. In general, an organic light emitting display device may include a plurality of R, G and B pixels which emit red light, green light and blue light. In the drawing, the outermost region and an outer part of pixels of two panels which are adjacent to each other are illustrated for the sake of explanation.

Referring toFIG. 1, an organic light emitting display device101according to the present disclosure may include a display part having a plurality of pixel regions for implementing a real image, and a pad part (or outer part) having a pad which is formed on an outer side of the display part for transferring an external signal into the display part.

A driving thin film transistor (TFT) may be formed on the display part of a substrate110which is made of a flexible material such as plastic. Although not shown, the driving TFT may be formed on each of the R, G and B pixel regions, and include a buffer layer122formed on the substrate110, a semiconductor layer112formed on the R, G and B pixel regions on the buffer layer122, a first insulating layer123formed on the entire substrate110having the semiconductor layer112, a gate electrode111formed on the first insulating layer123, a second insulating layer124formed on the entire substrate110to cover the gate electrode111, and a source electrode114and a drain electrode115which come in contact with the semiconductor layer112through contact holes formed through the first insulating layer123and the second insulating layer124.

The buffer layer122may be implemented into a single layer or a plurality of layers. The semiconductor layer112may be made of a transparent oxide semiconductor such as crystalline silicon or indium gallium zinc oxide (IGZO). The semiconductor layer112may include a channel layer on a central region thereof and doped layers on both sides thereof. The source electrode114and the drain electrode115may come in contact with the doped layers, respectively.

The gate electrode111may be made of a metal such as Cr, Mo, Ta, Cu, Ti, Al or Al alloy. The first insulating layer123and the second insulating layer124may have a single layer made of an inorganic insulating material such as SiO2or SiNx, or a dual layer made of SiO2and SiNx. Also, the source electrode114and the drain electrode115may be made of Cr, Mo, Ta, Cu, Ti, Al or Al alloy.

On the substrate110having the driving TFT may be formed a third insulating layer126. The third insulating layer126may be made of an inorganic insulating material such as SiO2.

Although not shown, an overcoat layer for planarizing the substrate110may be formed on the third insulating layer126.

Also, a common pad117may be formed on the second insulating layer124of the substrate110located on the pad part or the outer part. The common pad117may be formed to transfer a signal applied from the exterior into a common electrode within the display part. The common pad117may be formed by the same process as the source electrode114and the drain electrode115of the driving TFT.

Although not shown, the outer part may be provided with a gate pad for applying a scan signal to the gate electrode111of the driving TFT, and a data pad for applying a signal to a pixel electrode.

A first contact hole129amay be formed through the third insulating layer126on the drain electrode115of the driving TFT, which is formed on each pixel region of the display part. Accordingly, a pixel electrode120formed on the third insulating layer126may electrically come in contact with the drain electrode115of the driving TFT through the first contact hole129a.

A second contact hole129bmay also be formed through the third insulating layer126on the common pad117of the outer part, to externally expose the common pad117.

A bank layer128may be formed on a boundary between the adjacent pixel regions on the third insulating layer126within the display part. The bank layer128may be a type of barrier wall, which partitions each pixel region to prevent light of specific colors, output from adjacent pixel regions, from being output in a mixed state. Also, the bank layer128may reduce a stepped portion by filling a part of the contact hole129a. This may prevent the occurrence of a defective organic light emitting unit due to an excessive stepped portion during formation of the organic light emitting unit.

The bank layer128may extend to the outer part. Here, a contact hole may also be formed on the bank layer128located on the pad117of the outer part. Accordingly, the pad117may be externally exposed through the bank layer128. Meanwhile, an outer end portion of the bank layer128may be located on almost the same line with an end portion of the third insulating layer126, which may prevent a formation of a stepped portion between the third insulating layer126and the bank layer128.

The pixel electrode120may be formed on the display part and a metal layer121may be formed on the outer part. The pixel electrode120may be made of a metal, such as Ca, Ba, Mg, Al, Ag and the like, and connected to the drain electrode115of the driving TFT so as to allow for reception of an image signal applied from the exterior. The metal layer121, similar to the pixel electrode120, may be made of the metal, such as Ca, Ba, Mg, Al, Ag and the like. The metal layer121may reduce contact resistance between the common electrode, which is to be formed later, and the common pad117, allowing a signal to be transferred to the common electrode without delay.

The pixel electrode120and the metal layer121may be formed of the same metal by the same process. However, they may also be formed of different types of metals by different processes.

An organic light emitting unit125may be formed on the pixel electrode120on the bank layer128. The organic light emitting unit125may include an R-organic light emitting layer emitting red light, a G-organic light emitting layer emitting green light, and a B-organic light emitting layer emitting blue light. Although not shown, the organic light emitting unit125may also include, in addition to the organic light emitting layers, an electron injection layer and a hole injection layer formed on the organic light emitting layers for injecting electrons and holes into the organic light emitting layers, respectively, and an electron transport layer and a hole transport layer for transporting the injected electrons and holes to the organic light emitting layers, respectively.

Also, the organic light emitting layers may be implemented as a white organic light emitting layer for emitting white light. Here, R, G and B color filter layers may be formed below the white organic light emitting layer, for example, on R, G and B sub pixels regions on the insulating layer124, respectively, to convert the white light emitted from the white organic light emitting layer into red light, green light and blue light. The white organic light emitting layer may be formed by mixing a plurality of organic materials which emit RGB monochromic light, respectively, or by depositing a plurality of light emitting layers which emit RGB monochromic light, respectively.

A common electrode130may be formed on the organic light emitting unit125of the display part. The common electrode130may be made of transparent metal oxide, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

Here, the common electrode130may be an anode of the organic light emitting unit125and the pixel electrode120may be a cathode of the organic light emitting unit125. When a voltage is applied to the common electrode130and the pixel region120, electrons may be injected from the pixel electrode120into the organic light emitting unit125, and holes may be injected from the common electrode130into the organic light emitting unit125. The electrons and the holes may then be excited in the organic light emitting layer so as to generate excitons. As the excitons decay, light corresponding to an energy difference between lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the light emitting layer may be generated and emitted to the outside (toward an upper side of the common electrode130in the drawing).

Also, the common electrode130may also be formed on the second contact hole129bof the outer part. The common electrode130of the outer part may be connected to the common pad117through the metal layer121within the second contact hole129band also connected to the common electrode130of the display part, so as to allow an external signal to be applied to the common electrode130through the common pad117.

A first passivation layer141may be formed on the common electrode130of the outer part and the display part and on the bank layer128throughout the substrate110. The first passivation layer141may be made of an inorganic material such as SiO2or SiNx.

An organic layer142made of an organic material such as polymer or the like may be formed on the first passivation layer141, and a second passivation layer144made of an inorganic material such as SiO2or SiNx may be formed on the organic layer142.

An adhesive may be coated on the second passivation layer144to form an adhesive layer146, and a protection film148may be disposed on the adhesive layer146. Accordingly, the protection film148may be attached by virtue of the adhesive layer146.

Any material may be used as the adhesive if it has a high adhesive force, high thermal resistance, and high water resistance. The present disclosure may generally use thermosetting resin, such as epoxy-based compound, acrylate-based compound or acryl-based rubber. Here, the adhesive layer146may be coated by a thickness of about 5 to 100 μm, and cured (hardened) at temperature of about 80 to 170° C. Photocurable resin may also be used as the adhesive. In this case, the adhesive layer146may be cured by irradiating light such as ultraviolet rays.

The adhesive layer146may also serve as a sealing member for preventing permeation of moisture into the organic light emitting display device, as well as bonding the substrate110and the protection film148. Therefore, the reference numeral146is represented by the adhesive in the detailed description of the present disclosure but it is merely the sake for explanation. The adhesive layer may also be referred to as a sealing member.

The protection film148, an encapsulation cap for sealing (encapsulating) the adhesive layer146, may be implemented as polystyrene (PS) film polyethylene (PE) film, polyethylene naphthalate (PEN) film, polyimide (PI) film or the like.

A polarizing plate149may be attached onto the protection film148. The polarizing plate149may improve quality of image by allowing light emitted from the organic light emitting display device to be transmitted therethrough and prevent external incident light from being reflected thereby.

In the meantime, in the organic light emitting display device having the configuration, the driving TFT, the organic light emitting unit125, the pixel electrode120, the common electrode130, the various insulating layers and passivation layers may be formed on the display part, and various pads, insulating layers and passivation layers may be formed on the outer part. Here, any insulating layer and passivation layer may not be formed on an edge region of the outer part, namely, the outermost region of the organic light emitting display device. This will be explained hereinafter.

Referring toFIG. 2, the organic light emitting display device may be formed in a unit of mother substrate180. That is, as illustrated inFIG. 2, after forming a plurality of display panels181by forming the driving TFTs, various electrodes and various insulating layers on the mother substrate180through a variety of processes, the mother substrate180may be cut at dashed lines182by a cutting tool such as a cutting wheel or the like into unit display panels, thereby completely fabricating the organic light emitting display device.

FIG. 3is a sectional view taken along the line I-I′ ofFIG. 2, which illustrates that the mother substrate180is cut into unit panels by a cutting wheel. Here, the drawing merely illustrates only the outer parts of two adjacent display panels without the display part, for the sake of explanation.

Referring toFIG. 3, when the first passivation layer141and the second passivation layer144are formed on the outermost region of the organic light emitting display device, namely, between the adjacent display panels when being fabricated in the unit of mother substrate, upon cutting the mother substrate180having the first passivation layer141and the second passivation layer144by use of a cutting wheel184, the cutting wheel184may go down even into the mother substrate180through the first and second passivation layers141and144and the first substrate110.

Accordingly, cracks C may be generated on the first and second passivation layers141and144by the cutting wheel184. The cracks C may extend even down to the organic layer142located within the outer part along the first and second passivation layers141and144. The cracks C may become a permeating path of moisture and foreign materials. When the organic light emitting display device is fabricated, such moisture and foreign materials may permeate into the organic light emitting display device through the cracks C to cause a reduction of lifespan and a defect of the organic light emitting display device.

The applicant has executed several times a test of cutting a 4.3-inch organic light emitting display device formed as the unit of mother substrate under conditions that a temperature is 85° C. and moisture is 85%. It has been noticed from the repetitive test that probability that the cracks C, which are formed on the first and second passivation layers141and144by cutting the fabricated organic light emitting display device, reach the organic layer142is about 50%, and permeation of moisture and foreign materials is observed from all of the organic light emitting display devices having cracks.

As such, when the first passivation layer141and the second passivation layer144are formed between the adjacent panels, moisture may permeate into about 50% of organic light emitting display devices. The permeation of moisture may cause many problems in reliability of the organic light emitting display device.

On the other hand, the present disclosure may not form the first passivation layer141and the second passivation layer144between panels. Accordingly, cutting of the first and second passivation layers141and144by the cutting tool may not be needed to be executed when separating the organic light emitting display device into panel units by cutting the mother substrate. Therefore, any crack may not be formed on the first and second passivation layers141and144, which may result in preventing permeation of moisture through the crack.

When the test for cutting the 4.3-inch organic light emitting display device formed as the unit of mother substrate was executed by the applicant several times under a temperature of 85° C. and 85% moisture, any crack was not found in the organic light emitting display device fabricated according to the present disclosure and permeation of moisture and foreign materials was not observed.

FIGS. 4A to 4Hare views illustrating a method of fabricating an organic light emitting display device in accordance with the present disclosure.

As illustrated inFIG. 4A, a substrate110made of a plastic material such as polyimide (PI) may be attached onto a large mother substrate180made of glass or the like by using an adhesive. Here, the drawing merely illustrates two adjacent panel regions but the mother substrate180may include N×M (N, M≥2) panel regions. Therefore, N×M substrates110may be attached by a preset interval. Also, the substrates110having substantially the same area as that of the mother substrate180may be attached onto the mother substrate180.

Afterwards, a buffer layer122made of an inorganic material or the like may be formed on the substrate110. Here, the buffer layer122may be implemented into a single layer or a plurality of layers. Afterwards, transparent oxide semiconductor or crystalline silicon may be deposited on the entire substrate110by chemical vapor deposition (CVD), followed by etching, thereby forming a semiconductor layer112on the buffer layer122. Here, the crystalline silicon layer may be formed by depositing the crystalline silicon or by depositing amorphous silicon and crystallizing the amorphous silicon by various crystallization methods such as laser crystallization and the like. n+or p+type impurity may be doped on both side surfaces of the crystalline silicon layer, forming doped layers.

Afterwards, an inorganic insulating material such as SiO2or SiNx may be deposited on the semiconductor layer112by CVD to form a first insulating layer123. A non-transparent metal having high conductivity, such as Cr, Mo, Ta, Cu, Ti, Al or Al alloy may be deposited on the first insulating layer123by a sputtering process and etched by a photolithography process, thereby forming a gate electrode111on each pixel region of a display part. Then, an inorganic insulating material may be deposited on the entire substrate110having the gate electrode111by the CVD, thereby forming a second insulating layer124.

Here, the buffer layer122, the first insulating layer123and the second insulating layer124may also be formed on the outer part, except for the outermost region of the outer part, namely, on a region which is adjacent to another organic light emitting display panel and is to be cut later.

After forming contact holes for exposing the semiconductor layer112by etching the first and second insulating layers123and124, a non-transparent metal having high conductivity, such as Cr, Mo, Ta, Cu, Ti, Al or Al alloy may be deposited on the entire substrate110by the sputtering process and then etched, thereby forming a source electrode114and a drain electrode115, which are electrically connected to the semiconductor layer112through the contact holes, on the display part, and a pad117on the outer part.

As illustrated inFIG. 4B, an inorganic insulating material may be deposited on the entire substrate110having the source and drain electrode114and115and the pad117to form a third insulating layer126. The third insulating layer126may be partially etched to form a first contact hole129aand a second contact hole129b(seeFIG. 4D) on the display part and the outer part, respectively. Here, the third insulating layer126may be formed by depositing SiO2. Accordingly, the drain electrode115may be externally exposed through the first contact hole129a, and the pad117may be externally exposed through the second contact hole129b. The third insulating layer126may not be formed on the outermost region of the outer part, namely, a region which is adjacent to another organic light emitting display panel and is to be cut later.

Afterwards, a metal such as Ca, Ba, Mg, Al, or Ag may be deposited on the entire substrate110and then etched, thereby forming on the display part a pixel electrode120, which is connected to the drain electrode115of the driving TFT through the first contact hole129a, and the metal layer121on the outer part.

As illustrated inFIG. 4C, the bank layer128may be formed along the display part and the outer part. The bank layer128within the display part may partition each pixel region to prevent light of specific colors, output from adjacent pixel regions, from being output in a mixed state, and serve to reduce a stepped portion by filling a part of the first contact hole129a. Here, the bank layer128may be formed by depositing and etching an organic insulating material, or by depositing an inorganic insulating material by CVD and etching the material.

As illustrated inFIG. 4C, a transparent conductive material such as ITO or IZO may be deposited on the bank layer128and an organic light emitting unit125located at the bank layer128by the sputtering process, and then etched, to form a common electrode130. Here, the common electrode130may be connected to the pad117through the second contact hole129bvia the metal layer121, so as to allow a signal to be applied to the pad117within the display part. Then, as illustrated inFIG. 4D, an inorganic material may be deposited on the common electrode130and the bank layer128to form a first passivation layer141.

Here, the first passivation layer141may cover the insulating layers122and123of the outer part and a part of the first passivation layer141may further extend to be disposed directly on the substrate110. However, the first passivation layer141may not be formed on a region P which is adjacent to another organic light emitting display panel and is to be cut later.

Afterwards, as illustrated inFIG. 4E, an organic material such as polymer or the like may be deposited on the first passivation layer141to form an organic layer142. Here, the organic layer142may be formed by screen printing. That is, although not shown, after a screen is placed on the substrate110and polymer is deposited on the screen, pressure may be applied onto the polymer by a doctor blade or a roll, thereby forming the organic layer142.

The organic layer142may be about 8 to 10 μm thick and extend up to a preset region of the outer part, so as to completely cover the bank layer128. Or, the organic layer142may cover only a part of the bank layer128of the outer part or only up to an end portion of the bank layer128.

Afterwards, an inorganic material such as SiO2or SiNx may be deposited on the organic layer142, thereby forming a second passivation layer144on the organic layer142. Here, the second passivation layer144may extend up to an end portion of the first passivation layer141, but may not be formed on a region P which is adjacent to another organic light emitting display panel and is to be cut later.

As illustrated inFIG. 4F, an adhesive layer146may be formed by depositing an adhesive onto the second passivation layer144. A protection film148may be laid on the adhesive layer146to be pressed to adhere the protection film148. Here, thermosetting resin or photocurable resin may be used as the adhesive. For use of the thermosetting resin, heat may be applied after adhering the protection film148. For use of the photocurable resin, the protection film148may be adhered and light may be irradiated to cure the adhesive layer146.

Afterwards, a polarizing plate149may be attached onto the protection film148, thereby fabricating N×M organic light emitting electrode display panels on the mother substrate180.

Here, as illustrated, since the insulating layers and the passivation layers are not formed at all on a boundary area between the organic light emitting panels formed on the mother substrate180, a region P where the substrate110is exposed to the outside may be generated. When a plastic substrate110such as polyimide having a similar area to a display panel is attached onto the mother substrate180and a structure is formed on each substrate110, the plastic substrate may not be disposed between the adjacent panels. Therefore, glass of the mother substrate180may be exposed directly through the exposed region P.

Afterwards, as illustrated inFIG. 4G, a cutting wheel184may be aligned on the exposed region P between the adjacent panels. The cutting wheel184may then be driven to cut the mother substrate180and the substrate110to divide the mother substrate180into a plurality of unit panels. Here, since any passivation layers141and144are not formed on the exposed region P, cutting of the passivation layers141and144may not be caused. This may result in preventing generation of a crack on the passivation layer141and144during the cutting process.

The drawing merely illustrates that the cutting wheel is used to cut the mother substrate180. However, the present disclosure can also use a laser, such as a YAG laser or CO2laser, without being limited to the mechanical cutting wheel and.

As illustrated inFIG. 4H, the substrate110may be separated from the mother substrate180by irradiating laser beams L in a direction from the mother substrate180to each separated organic light emitting display panel or applying heat onto the display panel, thereby completely fabricating a flexible organic light emitting display device.

As described, a passivation layer may be removed from the outermost region of an outer part of a flexible organic light emitting display device. This may prevent cutting of any passivation layer by a cutting tool when a plurality of organic light emitting display devices are separated by cutting a mother substrate. This may prevent the production of cracks on the passivation layer due to the cutting, resulting in preventing permeation of moisture or foreign materials through the cracks.

Meanwhile, the detailed description illustrates an organic light emitting display device having a specific structure, but the present disclosure may not be limited to this. For example, the aforementioned organic light emitting display device merely has a structure that light is emitted upwardly, namely, through a protection film. However, the present disclosure may not be limited to the structure but be applicable to a structure that light is emitted downwardly, namely, through a substrate. In this case, a transparent conductive material may be used as a pixel electrode and a non-transparent metal may be used as a common electrode.

Also, the detailed description merely illustrates a driving TFT with a top-gate structure, but the present disclosure may also be applicable to a bottom gate structure and other various structures of TFTs.

In other words, the detailed description illustrates specific structures for a driving TFT, electrodes, and an organic light emitting unit, but the present disclosure may also be applicable to different structures without being limited to those specific structures. That is, if a passivation layer is not formed on an outermost region of an organic light emitting display device to expose a substrate, structures of a driving TFT, electrodes, and an organic light emitting unit, which have currently well known, may all be applied.