KR102351024B1 - Organic Light Emitting Diode Display - Google Patents

Abstract

The organic light emitting diode display device according to the present invention includes a substrate, a display element layer, a first inorganic layer, an organic layer, and a second inorganic layer. The substrate has a curved portion and a flat portion. The display element layer is disposed on the substrate. The first inorganic layer is disposed on the substrate to cover the display element layer. The organic layer is disposed on the first inorganic layer and has a concave-convex pattern provided on the curved portion. The second inorganic layer is laminated on the organic layer along the concave-convex pattern.

Description

Organic Light Emitting Diode Display

The present invention relates to an organic light emitting diode display in which a protective layer is formed to protect an internal element from moisture and oxygen. In particular, the present invention relates to an organic light emitting diode display having a concave-convex pattern on the protective layer in order to prevent cracks from occurring in the protective layer in a side bending structure.

Various flat display devices capable of reducing weight and volume, which are disadvantages of a cathode ray tube, are being developed. Such flat panel displays include a liquid crystal display device (LCD), a plasma display panel (PDP), an electrophoretic display device (EPD), and an organic light emitting diode display (OLED). Diode Display Device (OLED), etc.

Since the flat panel display device is thin and light in weight, it is widely used as a display means in a mobile communication terminal or a portable information processor. In particular, in portable or mobile devices, there is an increasing demand for a display panel that is thinner, lighter, and consumes less power. In particular, the organic light emitting diode display device is a self-emission type, and has advantages in that the luminance and viewing angle are large, the contrast ratio is excellent, and the response speed is fast.

A liquid crystal display or a plasma display has limitations in developing a self-luminous device having high flexibility and elasticity, and thus there is a limit to its application as a flexible display device. However, since the organic light emitting diode display device is formed using an organic thin film, interest is being focused on it as an optimal material that can be applied to a flexible display device using the flexibility and elasticity characteristic of the organic thin film.

Hereinafter, an organic light emitting diode display according to the related art will be described with reference to FIGS. 1 and 2 . 1 and 2 are cross-sectional views showing a schematic structure of an organic light emitting diode display device according to the related art, before and after bending the display device.

Referring to FIG. 1 , a conventional organic light emitting diode display device includes a substrate 1 , a display element layer 3 disposed on the substrate 1 , and a protective layer disposed to cover the display element layer 3 ( 4) is included.

The substrate 1 includes a display area AA displaying an image to be implemented, a non-display area NA disposed outside the display area AA to surround the display area AA, and the substrate 1 in contact with the substrate 1 . or includes a curved portion BA that can be bent. The substrate 1 may be formed of a plastic material having flexible properties. For example, the substrate 1 is PI (polyimide), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PC (polycarbonate), PES (polyethersulfone), PAR (polyarylate), PSF (polysulfone), COC (ciclic- It may be formed of a material such as olefin copolymer).

The display element layer 3 provided on the display area AA of the substrate 1 includes a plurality of pixel areas. Each pixel area includes at least one organic light emitting diode. The organic light emitting diode display may be driven by an active matrix (AM) or a passive matrix (PM). In the case of an active organic light emitting diode display, thin film transistors electrically connected to the organic light emitting diode may be disposed in the pixel region to drive the organic light emitting diode. An organic light emitting diode includes an anode electrode and a cathode electrode, and an organic light emitting layer interposed between the two electrodes.

Various devices such as thin film transistors and organic light emitting diodes provided in the display device layer 3 are very vulnerable to oxygen and moisture. Oxygen and moisture introduced into the inside may cause a shrinkage of the light emitting area due to deterioration of organic materials, shortening the lifespan of the devices, and may oxidize or corrode the devices, thereby causing current leakage and short circuit. Accordingly, the protective layer 4 capable of protecting the devices from ingress of moisture and oxygen is essential.

The protective layer 4 is formed to cover the display element layer 3 to prevent moisture and oxygen from flowing into the internal element. The protective layer 4 includes at least one inorganic layer, and an inorganic layer and an organic layer may be alternately disposed. For example, the protective layer 4 may include a first inorganic layer 5 , an organic layer 7 , and a second inorganic layer 9 that are sequentially stacked. The first and second inorganic layers 5 and 9 _{may be formed of silicon oxide (SiO 2} ) or silicon nitride (SiNx), which are inorganic materials, and function to block the inflow of moisture and oxygen.

In spite of the formation of the protective layer 4 to protect the devices from moisture and oxygen, the protective layer 4, in particular, when microcracks occur in the inorganic film constituting the protective layer 4, cracks As a result, oxygen and moisture may flow into the interior, which may cause device failure. For example, referring to FIG. 2 , when the curved portion BA is folded or bent in a bending direction, a large tensile stress is applied in the second inorganic layer 9 . In particular, the tensile stress may be concentrated on the curved portion BA to generate cracks in the second inorganic layer 9 of the curved portion BA. Cracks generated in the second inorganic layer 9 may propagate to the inside by deformation of the curved portion BA, and moisture and oxygen introduced according to the propagated cracks cause black spots and black line stains.

As such, the organic light emitting diode display device according to the prior art cannot prevent cracks that may occur on the inorganic film during bending, and can prevent device defects inside the display device due to moisture and oxygen introduced along the propagated cracks. There is a problem in that the reliability and stability of the product are lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic light emitting diode display in which a structure pattern of a protective layer is modified in order to prevent cracks in the protective layer when a substrate is bent or folded. In particular, it is an object of the present invention to provide an organic light emitting diode display device having a concave-convex pattern on the inorganic film to prevent cracks from occurring on the surface of the inorganic film constituting the protective layer.

In order to achieve the above object, an organic light emitting diode display device according to the present invention includes a substrate, a display element layer, a first inorganic film, an organic film, and a second inorganic film. The substrate has a curved portion and a flat portion. The display element layer is disposed on the substrate. The first inorganic layer is disposed on the substrate to cover the display element layer. The organic layer is disposed on the first inorganic layer and has a concave-convex pattern provided on the curved portion. The second inorganic layer is laminated on the organic layer along the concave-convex pattern.

The uneven pattern may be plural.

The concavo-convex pattern may have a trench shape extending along a bending axis direction that is a central axis of the bending direction.

The vertical cross-sectional shape of the concave-convex pattern may be a planar shape including a rectangle, a square, and a semicircle.

The horizontal cross-sectional shape of the concave-convex pattern may be at least one dot shape or a stripe shape extending in one direction.

The substrate may have a display area and a non-display area, and the curved portion may include a part of the display area and a part of the non-display area.

The display element layer may be disposed on a flat portion and may extend to a portion of the curved portion or all of the curved portion.

The present invention has an effect of preventing cracks from occurring in the inorganic film during bending by forming a concave-convex pattern on the inorganic film constituting the protective layer. Accordingly, the present invention can protect the internal elements of the organic light emitting diode display from moisture and oxygen that may be introduced through cracks, thereby improving the reliability and stability of the product.

1 and 2 are cross-sectional views showing a schematic structure of an organic light emitting diode display device according to the related art, before and after bending the display device.
3 is a plan view showing a schematic structure of an organic light emitting diode display device according to the present invention.
4 is a cross-sectional view showing the schematic structure of an organic light emitting diode display device according to the present invention, taken along line I-I' of FIG. 3 .
5 is a view for explaining an embodiment of the present invention, showing only the organic layer of the curved portion in FIG. 3 .
6 and 7 are enlarged views of only the R region in FIG. 3 and are views for explaining another embodiment of the present invention.
FIG. 8 is a view for explaining another embodiment of the present invention, showing only the organic layer of the curved portion in FIG. 3 .

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to substantially identical elements throughout. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the component names used in the following description may be selected in consideration of ease of writing the specification, and may be different from the component names of the actual product.

Hereinafter, an organic light emitting diode display according to the present invention will be described with reference to FIGS. 3 to 5 . 3 is a plan view showing a schematic structure of an organic light emitting diode display device according to the present invention. 4 is a cross-sectional view showing the schematic structure of an organic light emitting diode display device according to the present invention, taken along line I-I' of FIG. 3 . 5 is a view for explaining an embodiment of the present invention, showing only the organic layer of the curved portion in FIG. 4 .

Referring to FIG. 3 , an organic light emitting diode display according to the present invention includes a display area AA in which display elements for displaying image information are disposed, and a driving element for driving the display elements in the periphery of the display area AA. and a substrate SUB having a non-display area NA on which the elements are disposed. In addition, the substrate SUB has a curved portion BA capable of folding or bending the substrate SUB, and a flat portion FA maintaining the substrate SUB in a flat state.

The substrate SUB may be formed of a plastic material having a flexible characteristic. For example, the substrate is PI (Polyimide), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PC (polycarbonate), PES (polyethersulfone), PAR (polyarylate), PSF (polysulfone), COC (ciclic-olefin copolymer) It may be formed of a material such as

The display area AA is an area for displaying image information to be implemented. The non-display area NA is an area in which various circuits for displaying image information are disposed in the display area AA. In FIG. 3 , the display area AA is defined in the central portion of the substrate SUB and the non-display area NA surrounds the display area AA, but is not limited thereto, and the display area AA is not limited thereto. ) may be defined by extending to at least one side of the substrate SUB.

The curved portion BA is an area in which the substrate SUB can be bent or folded, and may be defined on any one side, both sides, or top, bottom, left, and right sides of the substrate SUB. As illustrated in FIG. 3 , the curved portion BA may be defined as an area including a part of the non-display area NA and a part of the display area AA. In this case, image information can be displayed not only on the flat portion FA but also on the curved portion BA. However, the present invention is not limited thereto, and the curved portion BA does not include the display area AA and may be defined in various ways as needed, such as defined within the non-display area NA. Hereinafter, for convenience of description, the display area AA is defined in the central portion of the substrate SUB, and the non-display area NA is defined to surround the display area AA at the outside of the display area AA, and A case in which the curved portion BA is defined on at least one side of the substrate SUB including a portion of the display area NA and a portion of the display area AA will be described as an example.

In the non-display area NA, a data driver (or Data Driving Integrated Circuit, not shown) for supplying a signal corresponding to image information to the data lines, and a gate driver (or a data driving integrated circuit, not shown) for supplying a scan signal to the gate lines , Gate Driving Integrated Circuit (not shown) may be disposed. In the case of high resolution in which the number of data lines and driving current lines increases, the data driver may be mounted on the outside of the substrate SUB, and data connection pads may be disposed instead of the data driver.

A display device layer DPL in which a plurality of pixel areas PA arranged in a matrix manner is defined is disposed in the display area AA. For example, the pixel areas PA may be defined as an MxN rectangle. However, it is not necessarily limited to this method, and may be arranged in various ways. Each of the pixel areas PA may have the same size or different sizes. In addition, three sub-pixels representing RGB (red, green, blue) colors may be regularly arranged as one unit. In the simplest structure, the pixel areas PA include a plurality of gate wires (not shown) running in a horizontal direction, a plurality of data wires (not shown) and a driving current wire (not shown) running in a vertical direction. It can be defined as the intersecting structure of

In each pixel area PA, an organic light emitting diode, which is a key component of an organic light emitting diode display, and thin film transistors for driving the organic light emitting diode are disposed. The thin film transistors may be formed in a thin film transistor area defined at one side of the pixel area PA. An organic light emitting diode includes an anode electrode and a cathode electrode, and an organic light emitting layer interposed between the two electrodes.

The anode electrode is formed to occupy a partial area in the pixel area PA, and is connected to the thin film transistor formed in the thin film transistor area. An organic light emitting layer is applied on the anode electrode, and the area where the anode electrode and the organic light emitting layer overlap is determined as the actual light emitting area. A cathode electrode is formed over the organic light emitting layer.

A passivation layer PASSI is formed to protect devices such as a thin film transistor and an organic light emitting diode disposed on the display device layer DPL from moisture and oxygen. The passivation layer PASSI is disposed to cover the devices.

Referring further to FIG. 4 to explain the present invention in more detail, the organic light emitting diode display according to the present invention includes a substrate SUB, a display element layer DPL disposed on the substrate, and a display element layer DPL. and a protective layer PASSI disposed to cover the .

The substrate SUB includes a display area AA displaying an image to be implemented, and a non-display area NA in which driving elements for displaying an image are disposed in the display area AA. In addition, the substrate SUB includes a curved portion BA capable of folding or bending the substrate, and a flat portion FA maintaining a flat state of the substrate SUB.

The display element layer DPL is disposed on the display area AA of the substrate SUB. The display element layer DPL may be disposed on the flat portion FA and may extend to a portion or all of the curved portion BA. The display element layer DPL includes a thin film transistor and a display element such as an organic light emitting diode electrically connected to the thin film transistor.

The present invention is not limited to the structure of the thin film transistor formed in the organic light emitting diode display. That is, the present invention may include a thin film transistor having various structures such as a bottom gate structure, a top gate structure, or a double gate structure.

An organic light emitting diode includes an anode electrode, a cathode electrode, and an organic light emitting layer interposed between the anode electrode and the cathode electrode. The organic light emitting layer includes at least one emission layer (EML), and a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and electrons. It may further include at least one or more of an electron injection layer (EIL).

A passivation layer PASSI is formed on the display element layer DPL to protect internal elements such as a thin film transistor and an organic light emitting diode from moisture and oxygen. The passivation layer PASSI covers the display element layer DPL and is formed to extend to the non-display area NA.

The passivation layer PASSI includes a first inorganic layer PAS1 , an organic layer PCL, and a second inorganic layer PAS2 . The first inorganic layer PAS1 and the second inorganic layer PAS2 may include inorganic insulating materials such as silicon nitride (SiNx) or silicon oxide (SiO ₂ ), and have a function of blocking the inflow of moisture and oxygen. do. The organic film (PCL) may include a polymer-based material such as an acrylic resin, an epoxy resin, or polyimide, and is interposed between the first inorganic film PAS1 and the second inorganic film PAS2 to form the inorganic film. It can function to relieve internal stress. The second inorganic layer PAS2 is formed to completely cover the organic layer PCL.

The passivation layer PASSI in FIG. 4 is exemplified as including only the first inorganic layer PAS1 , the organic layer PCL, and the second inorganic layer PAS2 , but is not limited thereto. Any structure that can be protected from For example, the passivation layer PASSI may have a structure in which a plurality of inorganic layers and organic layers are alternately stacked to block penetration of moisture and oxygen. The inorganic film formed on the organic film is preferably arranged so as to cover the organic film. That is, by forming the inorganic film to cover the sidewall of the organic film, it is possible to prevent in advance the penetration of defects or moisture into the internal element along the organic film from the outside. Hereinafter, a case in which the structure of the passivation layer PASSI is a structure in which the first inorganic layer PAS1 , the organic layer PCL, and the second inorganic layer PAS2 are sequentially stacked will be described as an example.

The first inorganic layer PAS1 covers the display element layer DPL and extends to the non-display area NA. An organic layer PCL is disposed on the first inorganic layer PAS1 . At least one concavo-convex pattern PTN is formed on the organic layer PCL of the curved portion BA. 5 , the concave-convex pattern PTN on the organic layer PCL may have a trench shape extending along the bending axis direction BAD, which is the central axis of the bending direction BD. When a plurality of concave-convex patterns PTN are formed, each concave-convex pattern PTN is disposed to be spaced apart from each other by a predetermined distance. In the present invention, in order to form the concave-convex pattern (PTN) on the organic layer (PCL), various processes such as screen printing and stamping may be used.

A second inorganic layer PAS2 is disposed on the organic layer PCL. Since the second inorganic layer PAS2 is formed by coating an inorganic material on the organic layer PCL, the second inorganic layer PAS2 of the curved portion BA has a concave-convex pattern PTN shape of the organic layer PCL. It is laminated along the ridges and has the concave-convex pattern PTN having the same shape as the concavo-convex pattern PTN of the organic layer PCL. According to the present invention, by forming the concave-convex pattern PTN on the second inorganic layer PAS2 , it is possible to prevent cracks that may occur during bending of the substrate SUB, compared to the case in which the concave-convex pattern PTN is not present.

In detail, when an external force for bending the substrate SUB is applied, tensile stress is generated in the second inorganic layer PAS2 to resist the external force. When the tensile stress exceeds the ultimate stress due to an increase in the external force, a crack occurs in the second inorganic layer PAS2 . In particular, since the second inorganic layer PAS2 corresponds to the outer surface of the passivation layer PASSI, the tensile stress is more severe. As a result, cracks are likely to occur on the upper surface of the second inorganic layer PAS2 .

In order to prevent this, in the present invention, a concave-convex pattern PTN is formed on the organic layer PCL of the curved portion BA, and an inorganic material is applied thereon to form a second inorganic layer PAS2 having the concave-convex pattern PTN. to form As the uneven pattern PTN is formed, the cross-sectional area of the second inorganic layer PAS2 is increased. As the cross-sectional area increases, the tensile stress acting on the second inorganic layer PAS2 may decrease, and thus cracks may be prevented from occurring in the second inorganic layer PAS2 .

(σ=인장 응력, P=외력, A=단면적)

(σ = tensile stress, P = external force, A = cross-sectional area)

For example, even when an external force equal to an external force capable of generating cracks in the inorganic film without the uneven pattern PTN is applied to the second inorganic film PAS2 of the present invention, the second inorganic film PAS2 of the present invention ), since the cross-sectional area is increased due to the formation of the concavo-convex pattern PTN, the tensile stress acting in the second inorganic layer PAS2 is reduced to less than the ultimate stress, thereby preventing cracks in the second inorganic layer PAS2 .

4 and 5 illustrate that two concave-convex patterns PTN are formed on the second inorganic layer PAS2 on the curved portion BA, but is not limited thereto, and includes at least one concave-convex pattern PTN. can do. Since the cross-sectional area of the second inorganic layer PAS2 increases as the number of the concave-convex patterns PTN increases, the present invention further reduces cracking of the second inorganic layer PAS2 by increasing the number of the concavo-convex patterns PTN. can be effectively prevented.

Although not shown in the drawings, a barrier film may be further disposed on the passivation layer PASSI to cover the passivation layer PASSI. The barrier film may be formed of a base layer and an adhesive layer made of a material such as a cycloolefin polymer or a PET polymer. The material of the base layer is not limited thereto, and any material capable of protecting the internal element from moisture and oxygen may be used.

On the base film, a touch screen panel through which a user directly contacts the screen with a hand or a conductive material to input information as needed may be disposed on the base film. A polarizing film may be disposed above or below the touch screen panel. The polarizing film may function to prevent reflection of light incident from the outside. A cover glass may be disposed on the touch screen panel.

Hereinafter, an organic light emitting diode display according to another embodiment of the present invention will be described with reference to FIGS. 6 and 7 . 6 and 7 are enlarged views of only the R region in FIG. 4 and are views for explaining another embodiment of the present invention.

The vertical cross-sectional shape of the concave-convex pattern PTN formed on the second inorganic layer PAS2 may be a rectangle or a square as shown in FIG. 4 , or a semicircular shape as shown in FIG. 6 . The vertical cross-sectional shape of the concave-convex pattern PTN is not limited thereto, and may include various planar shapes. That is, the vertical cross-sectional shape of the concavo-convex pattern PTN formed on the second inorganic layer PAS2 may include any shape capable of increasing the cross-sectional area of the second inorganic layer PAS2 .

Referring to FIG. 7 , when a plurality of concave-convex patterns PTNs are formed, each of the concave-convex patterns PTN may be formed to have different widths and/or lengths. For example, the width and/or length of the concave-convex pattern PTN formed in the region where the maximum tensile stress is applied during bending may be larger than the width and/or length of the adjacent concave-convex pattern PTN.

Hereinafter, an organic light emitting diode display according to another embodiment of the present invention will be described with reference to FIG. 8 . FIG. 8 illustrates only the organic layer of the curved portion in FIG. 4 , and is a view for explaining another embodiment of the present invention.

The horizontal cross-sectional shape of the concave-convex pattern PTN formed on the organic layer PCL may be a stripe shape extending in one direction as shown in FIG. 5 . Alternatively, referring to FIG. 8 , the concave-convex pattern PTN on the organic layer PCL may have a shape in which a plurality of dot patterns are arranged in the bending axis direction BAD, which is the central axis of the bending direction BD. In this case, the horizontal cross-sectional shape of the dot pattern may be various planar shapes including a square, a rectangle, a circle, and the like. The horizontal cross-sectional shape of the concave-convex pattern PTN is not limited thereto, and any shape capable of increasing the cross-sectional area of the second inorganic layer PAS2 may be included.

The structure of the pixel area PA of the organic light emitting diode display according to the present invention may be as follows. 9 is an example of an equivalent circuit diagram showing the structure of one pixel in the organic light emitting diode display according to the present invention. 10 is an example of a plan view showing the structure of one pixel in the organic light emitting diode display according to the present invention.

9 and 10 , the organic light emitting diode display includes a switching thin film transistor ST, a driving thin film transistor DT connected to the switching thin film transistor, and an organic light emitting diode OLED connected to the driving thin film transistor DT. do. The organic light emitting diode OLED includes an anode electrode ANO, a cathode electrode, and an organic light emitting layer OLE interposed between the anode electrode ANO and the cathode electrode.

A scan line SL, a data line DL, and a driving current line VDD are disposed on the substrate SUB to define a pixel area. An organic light emitting diode (OLED) is formed in the pixel area to define the light emitting area.

The switching thin film transistor ST is formed at an intersection of the scan line SL and the data line DL. The switching thin film transistor ST functions to select a pixel. The switching thin film transistor ST includes a gate electrode SG branching from the scan line SL, a source electrode SS, and a drain electrode SD. In addition, the driving thin film transistor DT serves to drive the organic light emitting diode OLED of the pixel selected by the switching thin film transistor ST. The driving thin film transistor DT includes a gate electrode DG connected to the drain electrode SD of the switching thin film transistor ST, a source electrode DS connected to the driving current line VDD, and a drain electrode DD do. The drain electrode DD of the driving thin film transistor DT is connected to the anode electrode ANO of the organic light emitting diode OLED. A bank BN is formed to expose the central portion of the anode electrode ANO. An organic light emitting layer OLE is formed on the exposed central portion of the anode electrode ANO. A cathode electrode is formed on the organic light emitting layer OLE. The cathode electrode is connected to the ground voltage (VSS). The storage capacitor is between the gate electrode DG of the driving thin film transistor DT and the driving current line VDD or between the gate electrode DG of the driving thin film transistor DT and the drain electrode DD of the driving thin film transistor DT. (Cst) is placed.

Those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Accordingly, the present invention should not be limited to the contents described in the detailed description, but should be defined by the claims.

SUB : Substrate BA : Curved part
FA : Flat part AA : Display area
NA: non-display area DPL: display element layer
PASSI: protective layer PAS1: first inorganic film
PCL: organic film PAS2: second inorganic film
PTN: Concave-convex pattern BD: Bending direction
BAD : bending axis direction PA : pixel area

Claims (7)

a substrate having a curved portion and a flat portion;
a display element layer disposed on the substrate;
a first inorganic layer disposed on the substrate to cover the display element layer;
an organic layer disposed on the first inorganic layer and having an uneven pattern provided on the curved portion; and
a second inorganic film laminated on the organic film along the concave-convex pattern;
The substrate has a display area and a non-display area;
The curved portion includes a portion of the display area and a portion of the non-display area.
The method of claim 1,
An organic light emitting diode display having a plurality of concavo-convex patterns.
The method of claim 1,
The concave-convex pattern has a trench shape extending along a bending axis direction serving as a central axis of the bending direction.
The method of claim 1,
The vertical cross-sectional shape of the concave-convex pattern is an organic light emitting diode display having a planar shape including a rectangle, a square, and a semicircle.
The method of claim 1,
The horizontal cross-sectional shape of the concave-convex pattern is a stripe shape extending in one direction or at least one dot type organic light emitting diode display.
delete The method of claim 1,
The display element layer is disposed on the flat portion, and the organic light emitting diode display is disposed to extend to a portion of the curved portion or all of the curved portion.

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