KR102623200B1 - Flexible substrate and flexible display device including the same - Google Patents

Abstract

The present invention relates to a flexible substrate and a flexible display device including the same. The flexible substrate of the present invention includes a first base layer and a second base layer, and the first base layer includes a resin and an organic-inorganic hybrid material. , the content of the organic-inorganic hybrid material is 30 to 70 wt% of the resin content, and the surface hardness of the first base layer is higher than that of the second base layer. Therefore, by omitting the back plate, the thickness of the flexible display device can be reduced, flexibility can be improved, and the area limitation problem can be solved.

Description

Flexible substrate and flexible display device including the same}

The present invention relates to a flexible display device, and more specifically, to a flexible substrate having light weight, thinness, and high rigidity characteristics, and a flexible display device including the same.

As society has entered a full-fledged information age, the display field, which processes and displays large amounts of information, has developed rapidly, and in response to this, liquid crystal display devices (LCDs) and organic light emitting displays (OLEDs) have developed rapidly. Various flat panel display devices such as Light Emitting display device (OLED) have been developed and are receiving attention.

Among these flat panel displays, the liquid crystal display device includes as its essential components a liquid crystal panel including an upper substrate and a lower substrate bonded with a liquid crystal layer containing liquid crystal molecules in between, and an electric field formed between the pixel electrode and the common electrode. The liquid crystal layer is driven by this to display an image.

In addition, the organic light emitting display device includes a light emitting diode including an anode and a cathode facing each other with an organic light emitting layer in between, and the holes and electrons injected from each of the anode and cathode combine in the organic light emitting layer to emit light. The video is displayed.

Meanwhile, recently, the demand for flexible display devices using flexible substrates is increasing. Flexible display devices are portable in a folded state and display images in an unfolded state, so they have the advantage of being able to display on a large screen and being easy to carry.

1 is a schematic cross-sectional view of a conventional flexible display device.

As shown in FIG. 1, a conventional flexible display device includes a display panel 10, a back plate 20 located below the display panel 10, and a cover window located above the display panel 10. Includes (30).

The display panel 10 is formed by forming an element layer including a plurality of elements on the flexible substrate (not shown) with a carrier substrate (not shown) attached to the bottom of the flexible substrate (not shown) and separating the carrier substrate. You can get it by (release) it.

In order to protect the display panel 10 from external shock, the cover window 30 is attached to the top of the display panel 10.

Additionally, since the flexible substrate of the display panel 10 is very thin, a back plate 20 is attached to the rear surface of the flexible substrate to protect the flexible substrate from the external environment.

Generally, the back plate 20 is made of polyethylene terephthalate. This back plate 20 has a thickness of 100 ㎛ or more to prevent damage such as scratches, which increases the thickness of the flexible display device and reduces the flexibility of the flexible display device.

In addition, the back plate 20 is attached to the flexible substrate of the display panel 10 through a lamination process, but the lamination process is not easy to apply to large-area display devices. Therefore, the conventional flexible display device including the back plate 20 has limitations in increasing the area.

Meanwhile, in order to improve adhesion between the flexible substrate and the carrier substrate during the manufacturing process of the display panel 10, the flexible substrate includes a silane coupling agent. However, this silane coupling agent may cause outgassing during a high temperature process, which causes defects in the display panel 10.

The present invention seeks to solve the problems of increased thickness and decreased flexibility of conventional flexible display devices.

Additionally, the present invention seeks to solve the area limitation problem of conventional flexible display devices.

Additionally, the present invention seeks to solve the problem of defects caused by gas ejection in conventional flexible display devices.

In order to achieve the above object, the flexible substrate according to the present invention includes a first base layer and a second base layer, the first base layer includes a resin and an organic-inorganic hybrid material, and the surface of the first base layer The hardness is higher than the surface hardness of the second base layer. At this time, the organic-inorganic hybrid material is a siloxane compound, and the content is 30 to 70 wt% of the resin content.

The resin may be made of melamine, acrylic, urethane, epoxy, or polyimide, and the second base layer may be made of polyimide.

Meanwhile, the flexible display device of the present invention includes a flexible substrate including a first base layer and a second base layer, a thin film transistor on the second base layer, and an organic light emitting diode or liquid crystal capacitor connected to the thin film transistor, and a first base layer. The base layer includes a resin and an organic-inorganic hybrid material, and the surface hardness of the first base layer is higher than that of the second base layer.

A flexible display device including a flexible substrate according to an embodiment of the present invention can reduce thickness and prevent deterioration of flexibility by omitting a back plate.

Additionally, since a lamination process for attaching a back plate is not required, the area limitation problem can be solved.

In addition, while not containing a silane coupling agent, adhesion with the sacrificial layer on the top of the carrier substrate can be improved, and defects caused by gas ejection due to the use of the silane coupling agent can be prevented.

1 is a schematic cross-sectional view of a conventional flexible display device.
Figure 2 is a schematic cross-sectional view of a flexible display device according to an embodiment of the present invention.
3A and 3B are schematic cross-sectional views showing an example of a display panel of a flexible display device according to an embodiment of the present invention.
Figure 4 is a schematic cross-sectional view of a flexible substrate according to an embodiment of the present invention.
Figure 5 is a graph showing the adhesive strength of a flexible substrate according to an embodiment of the present invention.
Figure 6 is a graph showing the adhesive strength of a flexible substrate according to an embodiment of the present invention depending on the content of the organic-inorganic hybrid material.
7A to 7F are cross-sectional views schematically showing the manufacturing process of a flexible display device according to an embodiment of the present invention.

The flexible substrate according to the present invention includes a first base layer and a second base layer on top of the first base layer, wherein the first base layer includes a resin and an organic-inorganic hybrid material, and the first base layer The surface hardness is higher than that of the second base layer.

The content of the organic-inorganic hybrid material is 30 to 70 wt% of the resin content.

The organic-inorganic hybrid material is a siloxane compound.

The siloxane compound is represented by the following formula, and R1 is epoxy acrylate or urethane acrylate.

The resin is made of melamine, acrylic, urethane, epoxy, or polyimide.

The second base layer is made of polyimide.

Meanwhile, the flexible display device of the present invention includes a flexible substrate including a first base layer and a second base layer, a thin film transistor on the flexible substrate, and an organic light emitting diode or liquid crystal capacitor connected to the thin film transistor, One base layer includes a resin and an organic-inorganic hybrid material, and the surface hardness of the first base layer is higher than that of the second base layer.

The second base layer is located between the first base layer and the thin film transistor.

Hereinafter, a flexible substrate and a flexible display device including the same according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic cross-sectional view of a flexible display device according to an embodiment of the present invention, and FIGS. 3A and 3B are schematic cross-sectional views showing an example of a display panel of a flexible display device according to an embodiment of the present invention.

As shown in FIGS. 2, 3A, and 3B, a display device according to an embodiment of the present invention includes a display panel 100 and a cover window 130 located on an upper portion of the display panel 100. The display panel 100 includes a flexible substrate 110 and a device layer 120 on the flexible substrate 110.

As shown in FIG. 3A, the display panel 100 may be an organic light emitting diode panel.

That is, the display panel 100 includes a flexible substrate 110, the device layer 120, a thin film transistor (Tr) located on the flexible substrate 110, and a light emitting device connected to the thin film transistor (Tr). It may include a diode (D) and an encapsulation film 180 covering the light emitting diode (D).

Here, the lower surface of the flexible substrate 110 has a higher surface hardness than the upper surface, and the flexible substrate 110 has a multi-layer structure, which will be described in detail later.

In more detail, a buffer layer 142 is formed on the flexible substrate 110, and a thin film transistor (Tr) is formed on the buffer layer 142. The buffer layer 142 may be made of an inorganic insulating material such as silicon oxide or silicon nitride. The buffer layer 142 may be omitted.

A semiconductor layer 144 is formed on the buffer layer 142. The semiconductor layer 144 may be made of an oxide semiconductor material or polycrystalline silicon.

When the semiconductor layer 144 is made of an oxide semiconductor material, a light blocking pattern (not shown) may be formed under the semiconductor layer 144, and the light blocking pattern prevents light from entering the semiconductor layer 144. This prevents the semiconductor layer 144 from being deteriorated by light. Alternatively, the semiconductor layer 144 may be made of polycrystalline silicon, and in this case, both edges of the semiconductor layer 144 may be doped with impurities.

A gate insulating film 146 made of an insulating material is formed on the semiconductor layer 144. The gate insulating film 146 may be made of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 150 made of a conductive material such as metal is formed on the gate insulating film 146 corresponding to the center of the semiconductor layer 144.

In FIG. 3A, the gate insulating film 146 is formed on the entire surface of the flexible substrate 110, but the gate insulating film 146 may be patterned to have the same shape as the gate electrode 150.

An interlayer insulating film 152 made of an insulating material is formed on the gate electrode 150. The interlayer insulating film 152 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or may be formed of an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating film 152 has first and second contact holes 154 and 156 exposing both sides of the semiconductor layer 144. The first and second contact holes 154 and 156 are located on both sides of the gate electrode 150 and are spaced apart from the gate electrode 150 .

Here, the first and second contact holes 154 and 156 are also formed within the gate insulating film 146. Alternatively, when the gate insulating layer 146 is patterned to have the same shape as the gate electrode 150, the first and second contact holes 154 and 156 may be formed only in the interlayer insulating layer 152.

A source electrode 160 and a drain electrode 162 made of a conductive material such as metal are formed on the interlayer insulating film 152.

The source electrode 160 and the drain electrode 162 are positioned spaced apart from each other around the gate electrode 150, and are provided on both sides of the semiconductor layer 144 through the first and second contact holes 154 and 156, respectively. come into contact with

The semiconductor layer 144, the gate electrode 150, the source electrode 160, and the drain electrode 162 form the thin film transistor (Tr), and the thin film transistor (Tr) is a driving element. ) functions as

The thin film transistor (Tr) has a coplanar structure in which the gate electrode 150, the source electrode 160, and the drain electrode 162 are located on the semiconductor layer 144.

In contrast, the thin film transistor (Tr) may have an inverted staggered structure in which the gate electrode is located at the bottom of the semiconductor layer and the source electrode and drain electrode are located at the top of the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Although not shown, gate wires and data wires intersect each other to define a pixel area, and a switching element connected to the gate wire and data wire is further formed. The switching element is connected to a thin film transistor (Tr), which is a driving element.

In addition, a power wire is formed parallel to and spaced apart from the gate wire or the data wire, and a storage capacitor is further provided to maintain the voltage of the gate electrode of the thin film transistor (Tr), which is a driving element, constant during one frame. It can be configured.

A protective layer 164 having a drain contact hole 166 exposing the drain electrode 162 of the thin film transistor Tr is formed to cover the thin film transistor Tr.

On the protective layer 164, a first electrode 170 connected to the drain electrode 162 of the thin film transistor (Tr) through the drain contact hole 166 is formed separately for each pixel area. The first electrode 170 may be an anode and may be made of a conductive material with a relatively high work function value. For example, the first electrode 170 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). .

Meanwhile, when the display panel 100 of the present invention is a top-emission type organic light emitting diode panel, a reflective electrode or a reflective layer may be further formed below the first electrode 170. For example, the reflective electrode or the reflective layer may be made of aluminum-palladium-copper (APC) alloy.

Additionally, a bank layer 176 covering the edge of the first electrode 170 is formed on the protective layer 164. The bank layer 176 exposes the center of the first electrode 170 corresponding to the pixel area.

An organic light-emitting layer 172 is formed on the first electrode 170. The organic light-emitting layer 172 may have a single-layer structure of an emitting material layer made of a light-emitting material. On the other hand, in order to increase luminous efficiency, the organic light-emitting layer 172 includes a hole injection layer, a hole transporting layer, a light-emitting material layer, and an electronic layer sequentially stacked on the first electrode 170. It may have a multi-layer structure of an electron transporting layer and an electron injection layer.

A second electrode 174 is formed on the flexible substrate 110 on which the organic light emitting layer 172 is formed. The second electrode 174 is located in front of the display area and is made of a conductive material with a relatively low work function value and can be used as a cathode. For example, the second electrode 174 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

The first electrode 170, the organic light emitting layer 172, and the second electrode 174 form a light emitting diode (D).

An encapsulation film 180 is formed on the second electrode 174 to prevent external moisture from penetrating into the light emitting diode (D). The encapsulation film 180 may have a stacked structure of a first inorganic insulating layer 182, an organic insulating layer 184, and a second inorganic insulating layer 186, but is not limited to this.

Additionally, a polarizing plate (not shown) may be attached to the encapsulation film 180 to reduce external light reflection. For example, the polarizer may be a circular polarizer.

Meanwhile, as shown in FIG. 3B, the display panel 100 may be a reflective liquid crystal panel.

That is, the display panel 100 includes first and second flexible substrates 110 and 250 facing each other, and is interposed between the first and second flexible substrates 110 and 250 and includes liquid crystal molecules 262. It may include a liquid crystal layer 260. In addition, although not shown, a reflective layer is located between the liquid crystal layer 260 and the first flexible substrate 110.

Here, the lower surface of the flexible substrate 110 has a higher surface hardness than the upper surface, and the flexible substrate 110 has a multi-layer structure, which will be described in detail later.

A first buffer layer 220 is formed on the first flexible substrate 110, and a thin film transistor (Tr) is formed on the first buffer layer 220. The first buffer layer 220 may be omitted.

A gate electrode 222 is formed on the first buffer layer 220, and a gate insulating film 224 is formed covering the gate electrode 222. Additionally, a gate wire (not shown) connected to the gate electrode 222 is formed on the buffer layer 220.

A semiconductor layer 226 is formed on the gate insulating film 224 to correspond to the gate electrode 222. The semiconductor layer 226 may be made of an oxide semiconductor material. Meanwhile, the semiconductor layer 226 may include an active layer made of amorphous silicon and an ohmic contact layer made of impurity amorphous silicon.

A source electrode 230 and a drain electrode 232 are formed on the semiconductor layer 226 and are spaced apart from each other. Additionally, a data wire (not shown) connected to the source electrode 230 is formed to intersect the gate wire to define a pixel area.

The gate electrode 222, the semiconductor layer 226, the source electrode 230, and the drain electrode 232 constitute a thin film transistor (Tr).

A protective layer 234 having a drain contact hole 236 exposing the drain electrode 232 is formed on the thin film transistor Tr.

On the protective layer 234, a pixel electrode 240 is connected to the drain electrode 232 through the drain contact hole 236, and a common electrode 242 is alternately arranged with the pixel electrode 240. is formed

A second buffer layer 252 is formed on the second flexible substrate 250, and on the second buffer layer 252, a black matrix ( 254) is formed. Additionally, a color filter layer 256 is formed corresponding to the pixel area. The second buffer layer 252 and the black matrix 254 may be omitted.

The first and second flexible substrates 110 and 250 are bonded with a liquid crystal layer 260 therebetween, and the liquid crystal layer ( The liquid crystal molecules 262 of 260 are driven. The pixel electrode 240, the common electrode 242, and the liquid crystal layer 260 form a liquid crystal capacitor, and the liquid crystal capacitor is connected to the thin film transistor (Tr).

Although not shown, an alignment film may be formed on the top of each of the first and second flexible substrates 110 and 250 in contact with the liquid crystal layer 260, and an alignment layer may be formed on the outside of the second flexible substrate 250 in a specific direction. A polarizing plate that transmits only linearly polarized light may be attached.

Here, the common electrode 242 is alternately arranged with the pixel electrode 240 on the top of the first flexible substrate 110. The common electrode is formed on the front surface of the second flexible substrate 250, and the pixel electrode 242 is formed on the front of the second flexible substrate 250. The electrode 240 may be formed in a plate shape in the pixel area.

As mentioned earlier, this liquid crystal panel 100 uses external light as a light source and may be a reflective liquid crystal panel that reflects external light and outputs the output.

Referring again to FIG. 1, the cover window 130 is located above the display panel 100. For example, the cover window 130 may be made of transparent plastic and may be attached to the display panel 100 using an adhesive layer (not shown).

As such, the lower surface of the flexible substrate 110 has a higher surface strength than the upper surface, and the flexible display device according to an embodiment of the present invention does not include a back plate. At this time, the surface hardness of the lower surface of the flexible substrate 110 may be 4H or more.

A flexible substrate according to an embodiment of the present invention will be described in detail with reference to the drawings.

Figure 4 is a schematic cross-sectional view of a flexible substrate according to an embodiment of the present invention.

As shown in FIG. 4, the flexible substrate 110 according to an embodiment of the present invention includes a first base layer 112 and a second base layer 114 on top of the first base layer 112. .

The first base layer 112 includes a resin and an organic-inorganic hybrid material, and the first base layer 112 has a higher surface hardness than the second base layer 114.

Here, the second base layer 114 is made of an organic material. For example, it may be made of polyimide, but is not limited thereto.

Meanwhile, the resin of the first base layer 112 may be made of melamine, acryl, urethane, epoxy, or polyimide, but is not limited thereto.

Additionally, the organic-inorganic hybrid material of the first base layer 112 may be a siloxane compound, and the siloxane compound may be represented by Formula 1 below.

Formula 1

Here, R1 may be epoxy acrylate or urethane acrylate, but is not limited thereto.

The content of the organic-inorganic hybrid material may preferably be 30 to 70 wt% of the resin content, and more preferably 50 to 70 wt%. That is, the content of the organic-inorganic hybrid material may be greater than the resin content. When the content of the organic-inorganic hybrid material is less than 30 wt%, the adhesive strength of the first base layer 112 to the inorganic film is lowered, so that when forming the device layer (120 in FIG. 2), it is separated from the carrier substrate to the flexible substrate. There is a problem with (110) being peeled off. On the other hand, if the content of the organic-inorganic hybrid material is more than 70 wt%, the elasticity of the first base layer 112 decreases and becomes brittle, which poses a problem in applying it to a flexible display device.

This flexible substrate 110 has a thickness of 20 to 70 ㎛. At this time, the first base layer 112 may have a thickness of 10 to 20 ㎛, and the second base layer 114 may have a thickness of 10 to 50 ㎛.

As previously mentioned, the first base layer 112 has a higher surface hardness than the second base layer 114. At this time, the surface hardness of the first base layer 112 may be equal to or greater than 4H. Since the surface hardness of the first base layer 112 is higher than that of the conventional back plate (20 in FIG. 1) of 2H or less, the thickness of the flexible display device can be reduced and flexibility increased by omitting the back plate. , scratch resistance can be improved.

In addition, the water vapor transmission rate (WVTR) of the first base layer 112 is about 10 ^-4 g/m ² ·day, compared to the conventional back plate (FIG. 1) which is about 10 ¹ g/m ² ·day Because it is lower than the moisture permeability of 20), the moisture barrier properties are improved.

Meanwhile, the transmittance of the first base layer 112 is less than 90%, and the haze value is greater than 1.

Additionally, the adhesive strength of the first base layer 112 to the inorganic film is greater than that of the second base layer 114. For example, the inorganic film may be an amorphous silicon film, and the adhesive strength of the first base layer 112 to the inorganic film may be 0.3 N/cm or more, preferably 0.3 to 1.6 N/cm.

Figure 5 is a graph showing the adhesive strength of a flexible substrate according to an embodiment of the present invention, showing the adhesive strength to an inorganic film. Here, the flexible substrate according to an embodiment of the present invention includes a first base layer made of resin and an organic-inorganic hybrid material of Formula 1 above, and a second base layer made of polyimide without a silane coupling agent.

As shown in Figure 5, the flexible substrate according to an embodiment of the present invention has an adhesive strength of 0.3 N/cm or more.

On the other hand, the flexible substrate of Comparative Example 1 was made of polyimide without a silane coupling agent, and the flexible substrate of Comparative Example 1 had an adhesive strength of 0.05 to 0.07 N/cm.

In addition, the flexible substrate of Comparative Example 2 is made of polyimide containing a silane coupling agent, and the flexible substrate of Comparative Example 2 has an adhesive strength of 0.3 to 0.4 N/cm.

As such, the flexible substrate according to an embodiment of the present invention does not contain a silane coupling agent, but has an adhesive strength higher than that of Comparative Example 2, which includes a silane coupling agent. Accordingly, when forming a device layer on a flexible substrate, peeling of the flexible substrate from the carrier substrate can be prevented and defects caused by the silane coupling agent can be prevented.

Figure 6 is a graph showing the adhesive strength of the flexible substrate according to an embodiment of the present invention according to the content of the organic-inorganic hybrid material, showing the adhesive strength to the inorganic film.

Here, the flexible substrate according to an embodiment of the present invention includes a first base layer made of resin and an organic-inorganic hybrid material of Formula 1 above, and a second base layer made of polyimide without a silane coupling agent. In Experiment 1, the content of the organic-inorganic hybrid material is 30 wt%, in Experiment 2, the content of the organic-inorganic hybrid material is 50 wt%, and in Experiment 3, the content of the organic-inorganic hybrid material is 70 wt%.

Meanwhile, the flexible substrate of the comparative example has an organic-inorganic hybrid material content of 10 wt%.

As shown in Figure 6, the flexible substrate according to an embodiment of the present invention has an adhesive strength of 0.3 N/cm or more.

More specifically, the flexible substrate of Experimental Example 1 had an adhesive strength of 0.37 to 0.45 N/cm, the flexible substrate of Experimental Example 2 had an adhesive strength of 0.74 to 0.80 N/cm, and the flexible substrate of Experimental Example 3 had an adhesive strength of 1.51 N/cm. It has an adhesive strength of 1.56 N/cm.

On the other hand, the flexible substrate of the comparative example had an adhesive strength of 0.07 to 0.09 N/cm.

As such, the flexible substrate according to the embodiment of the present invention has a higher adhesive strength than the comparative example, and as the content of the organic-inorganic hybrid material increases, the adhesive strength increases.

Meanwhile, as the content of the organic-inorganic hybrid material increases, surface hardness also increases. More specifically, the surface hardness of Experimental Example 1 is 4H, the surface hardness of Experimental Example 2 is 5 to 6H, and the surface hardness of Experimental Example 3 is 8 to 9H. On the other hand, the surface hardness of the comparative example was 3 to 4H.

Additionally, as the content of the organic-inorganic hybrid material increases, the transmittance decreases and the haze value increases. More specifically, the transmittance of Experimental Example 1 is 89% and the haze value is 1.18, the transmittance of Experimental Example 2 is 87% and the haze value is 2.04, and the transmittance of Experimental Example 3 is 86% and the haze value is 2.99. On the other hand, the transmittance of the comparative example was 91% and the haze value was 0.63.

The manufacturing process of a flexible display device including a flexible substrate according to an embodiment of the present invention will be described with reference to FIGS. 7A to 7F.

7A to 7F are cross-sectional views schematically showing the manufacturing process of a flexible display device according to an embodiment of the present invention.

As shown in FIG. 7A, a sacrificial layer 320 is formed on the carrier substrate 310. Here, the sacrificial layer 320 is an inorganic film and may be formed through a deposition process. For example, the sacrificial layer 320 may be made of amorphous silicon. Additionally, the carrier substrate 310 may be made of glass.

Next, as shown in FIG. 7B, a resin containing an organic-inorganic hybrid material is coated on the sacrificial layer 320 and then cured to form a first base layer 112.

Next, as shown in FIG. 7C, polyimide resin is coated on the first base layer 112 and then cured to form the second base layer 114. The first base layer 112 and the second base layer 114 form the flexible substrate 110.

Next, as shown in FIG. 7D, a device layer 120 is formed on the second base layer 114 of the flexible substrate 110. The device layer 120 includes a thin film transistor and an organic light emitting diode or liquid crystal capacitor connected to the thin film transistor.

At this time, the first base layer 112 has an adhesive strength of 0.3 to 1.6 N/cm to the inorganic film, and the flexible substrate 110 peels off from the sacrificial layer 320 during the device layer 120 forming process. ) can be prevented.

Next, as shown in FIG. 7E, a laser is irradiated from the back of the carrier substrate 310 to change the crystallinity of the sacrificial layer 320. Accordingly, the flexible substrate 110 on which the device layer 120 is formed is separated from the sacrificial layer 320 on the carrier substrate 310.

Therefore, as shown in FIG. 7F, a display panel consisting of a flexible substrate 110 and a device layer 120 is manufactured. Next, the flexible display device can be completed by attaching a cover window (130 in FIG. 2) on top of the device layer 120.

In this way, the flexible display device including the flexible substrate 110 according to an embodiment of the present invention can reduce the thickness and prevent a decrease in flexibility by omitting the back plate. Additionally, since a lamination process is not required, the area limitation problem can be solved. In addition, without containing a silane coupling agent, adhesion with the sacrificial layer 320 can be improved, and defects caused by the silane coupling agent can be prevented.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may modify the present invention in various ways without departing from the technical spirit and scope of the present invention as set forth in the claims below. and that it can be changed.

100: display panel 110: flexible substrate
120: device layer 130: cover window
112: first base layer 114: second base layer

Claims (8)

a flexible substrate;
A thin film transistor on the flexible substrate; and
Organic light emitting diode or liquid crystal capacitor connected to the thin film transistor
Including,
The flexible substrate includes a first base layer; It includes only a second base layer on top of the first base layer, and the second base layer is located between the first base layer and the thin film transistor,
The second base layer is made of polyimide resin,
The first base layer includes a resin and an organic-inorganic hybrid material,
The surface hardness of the first base layer is higher than the surface hardness of the second base layer,
The organic-inorganic hybrid material is a siloxane compound represented by the following formula,

R1 is epoxy acrylate or urethane acrylate,
A flexible display device wherein the first base layer has an adhesive strength to an inorganic layer of 0.3 to 1.6 N/cm.
According to paragraph 1,
A flexible display device wherein the content of the organic-inorganic hybrid material is 30 to 70 wt% of the resin content.
According to paragraph 1,
A flexible display device wherein the inorganic layer is an amorphous silicon layer.
According to paragraph 1,
The first base layer is a flexible display device having a transmittance of less than 90% and a haze value of more than 1.
According to paragraph 1,
A flexible display device in which the resin is made of melamine, acrylic, urethane, epoxy, or polyimide.
According to paragraph 1,
The second base layer is a flexible display device made of polyimide resin that does not contain a silane coupling agent.
According to paragraph 1,
The flexible substrate is,
The resin containing the organic-inorganic hybrid material is coated on the inorganic film formed through a deposition process on the carrier substrate and then cured to form the first base layer,
The polyimide resin is coated on top of the first base layer and cured to form the second base layer,
After forming the thin film transistor and the organic light-emitting diode or liquid crystal capacitor on the second base layer, a laser is irradiated from the back of the carrier substrate to change the crystallinity of the inorganic film, thereby converting the first base layer into the inorganic film. A flexible display device formed by separating from.
According to paragraph 1,
A flexible display device wherein the first surface of the first base layer is in contact with the second base layer, and the second surface of the first base layer is exposed to the outside.

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