Display panel having a recess disposed in the transistion area

A display panel and a display device are provided. The display panel is divided into a display area, a transition area, and a bending area. The display panel includes a first recess and a second recess. The first recess is disposed in the bending area, and the second recess is disposed in the transition area.

RELATED APPLICATIONS

This application is a National Phase of PCT Patent Application No. PCT/CN2019/115516 having International filing date of Nov. 5, 2019, which claims the benefit of priority of Chinese Patent Application No. 201910800472.8 filed on Aug. 28, 2019. The contents of the above applications are all incorporated by reference as if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present disclosure relates to the field of display technologies, and more particularly to a display panel and a display device.

Organic light emitting diode (OLED) display panels are display panels made of organic self-illuminating diodes. Because the OLED display panels have self-illuminating organic electroluminescent diodes, the OLED display panels have characteristics of no backlight, high contrast, thin thickness, wide viewing angles, fast response speed, being used for flexible panels, wide temperature ranges, simple structures, and simple processes.

Specifically, the reason why the OLED display panels are flexible is that glass substrates of conventional OLED panels are not used, but a material such as plastic or metal is used as substrates. In addition to the flexibility of the OLED display panels, due to the difference in the material and composition of the substrates, the OLED display panels have large shatterproof capability and are also lighter and thinner. In addition, since the OLED display panels are self-illuminating, the OLED display panels can be pure black when displaying the darkest color. Regarding viewing angles of the OLED display panels, the OLED display panels are not distorted even under large viewing angles. The OLED display panels still have good color uniformity, good color accuracy, and good visual experience in a flexible state and thus become a new generation of trend technology that replaces liquid crystal displays.

At present, full-screen borderless display products can enable users to get a better viewing experience, which will definitely ignite a new consumer market. Pad Bending is a core technology of full-screen borderless OLED display products, so each company is developing pad bending technology to reduce a size of a frame and achieve a larger screen ratio.

As shown inFIG. 1, a display panel includes a flexible substrate1, a buffer layer2, an array substrate3, a pixel defining layer5, a supporting layer6, and a thin film encapsulation layer9. The array substrate includes a gate insulating layer32, a first source drain layer35, and a first planarization layer36. The thin film encapsulation layer9includes a first inorganic layer91, an organic layer92, and a second inorganic layer93. The display panel is divided into a display area100, a transition area200, and a bending area300. In the prior art, an organic filling layer (ODH)101is disposed at a position corresponding to the buffer layer2and the gate insulating layer32of the bending area300. Thereby, stress in the bending area is lowered, while a dam102is disposed in the transition area between the bending area and the display ara, thereby preventing overflow of the inkjet printing (IJP) material in the organic layer92. However, setting the dam102tends to cause an increase in a width of the transition area200, so that a frame of the display panel is increased, which is disadvantageous for achieving a narrow frame.

SUMMARY OF THE INVENTION

An object of the present invention provides a display panel and a display device to solve technical problems that a transition area has a large width and is disadvantageous for the display panel to realize a narrow frame.

In order to achieve the above object, an embodiment of the present invention provides a display panel. The display panel is divided into a display area, a transition area, and a bending area. The display panel includes a flexible substrate, a buffer layer, an array substrate, a pixel defining layer, a support layer, and a thin film encapsulation layer which are stacked in a stack, a first recess, and a second recess. The array substrate includes a gate insulating layer, a dielectric layer, a first planarization layer, a second source drain layer, and a second planarization layer. The first recess is disposed in the bending area, the first recess penetrates through the dielectric layer, the gate insulating layer, and the buffer layer, and is recessed in a side surface of the flexible substrate. The second recess is disposed in the transition area, and the second recess penetrates through the support layer, the pixel defining layer, the second planarization layer, and the first planarization layer.

In an embodiment of the present invention, the first planarization layer fills the first recess, and the thin film encapsulation layer fills the second recess.

In an embodiment of the present invention, the buffer layer is provided with a buffer through hole in the bending area, the array substrate is provided with a gate insulating through hole and an electrical layer through hole in the bending area, and the buffer through hole is opposite to the gate insulating through hole and the dielectric through hole.

In an embodiment of the present invention, the array substrate is provided with a first planarization through hole and a second planarization through hole in the transition area, the pixel defining layer is provided with a pixel defining through hole in the transition area, the support layer is provided with a support through hole in the transition area, and the first planarization through hole is opposite to the second planarization through hole, the pixel defining through hole, and the support through hole.

In an embodiment of the present invention, the flexible substrate includes a first substrate, an insulating layer disposed on a surface of a side of the first substrate, and a second substrate disposed on a surface of the insulating layer away from a side of the first substrate. A recess of the second substrate is recessed on a surface of a side of the second substrate and is disposed opposite to the buffer through hole in the bending area.

In an embodiment of the present invention, a thickness of the second substrate in the bending area is less than a thickness of the second substrate in the display area or the transition area, and the thickness of the second substrate in the bending area ranges between 2 um and 8 um.

In an embodiment of the present invention, the array substrate further includes a first source drain layer, the first source drain layer extends from the transition area to the bending area, and the second source drain layer extends from the transition area to the bending area.

In an embodiment of the present invention, the first source drain layer is disposed on an upper surface of the dielectric layer in the transition area, and the second source drain layer is disposed on an upper surface of the first planarization layer and connected to the first source drain layer in the transition area.

In an embodiment of the present invention, the first source drain layer is disposed on a sidewall and a bottom surface of the first recess in the bending area, and the second source drain layer is disposed on an upper surface of the first planarization layer in the bending area.

An embodiment of the present invention further provides a display device including the above display panel.

Beneficial effects of an embodiment of the present disclosure are that, the display panel and the display device are provided. On one hand, providing the first recess in the bending area can improve the bending characteristics of the display panel, reduce risk of disconnection, and increase a service life. On another hand, providing the second recess in the transition area can reduce a width of the transition area, so that the display panel realizes an ultra-narrow frame, thereby further increasing a screen ratio of the display panel.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The preferred embodiments of the present invention are described below with reference to the accompanying drawings, which are used to exemplify the embodiments of the present invention, which can fully describe the technical contents of the present invention to make the technical content of the present invention clearer and easy to understand. However, the present invention may be embodied in many different forms of embodiments, and the scope of the present invention is not limited to the embodiments set forth herein.

As shown inFIG. 2, an embodiment of the present invention provides a display panel, which is divided into a display area100, a transition area200, and a bending area300from a left side to a right side inFIG. 2. The display area100is used to implement a display function. The bending area300is provided with a relevant circuit module, and is bent below the display panel to place the relevant circuit module in a space below the display panel. The transition area200is disposed between the display area100and the bending area300for connecting the display area100with the bending area300. In this embodiment, a first recess120is disposed in the bending area300to improve a bending property of the display panel and reduce a risk of wire breakage of a metal trace in the bending area300. A second recess121is disposed in the transition area200to implement an ultra-narrow frame of the display panel.

The display panel includes a flexible substrate1, a buffer layer2, an array substrate3, a first electrode4, a pixel defining layer5, a support layer6, a light emitting layer7, a second electrode8, and a thin film encapsulation layer9, in an order from a bottom to a top inFIG. 2.

The flexible substrate1includes a first substrate11, an insulating layer12, a second substrate13, and a second substrate recess110. The first substrate11is a PI substrate made of polyimide and having a thickness of 10 μm. The insulating layer12is provided on an upper surface of the first substrate11, and a material of the insulating layer12is a material having water absorption properties such as silicon nitride (SiNx) or silicon oxide (SiOx). The second substrate13is provided on an upper surface of the insulating layer12, and the second substrate13is a PI substrate made of polyimide. The second substrate recess110is recessed to an upper surface of the second substrate13located in the bending area300. In the embodiment, a thickness of the second substrate13is not uniform. A thickness of the second substrate13in the bending area300is less than a thickness of the second substrate13in the display area100or the transition area200. In one embodiment, the second substrate13located in the display area100and the transition area200has a thickness of 10 um, and the second substrate13located in the bending area300has a thickness of 2 um to 8 um.

The buffer layer2is disposed on an upper surface of the flexible substrate1, and the buffer layer2located in the bending area300forms a buffer through hole111. The buffer through hole111is disposed opposite to the second substrate recess110.

The array substrate3is provided on an upper surface of the buffer layer2. The array substrate3is formed with a plurality of through holes. The array substrate3includes an active layer31, a gate insulating layer32, a gate layer33, a dielectric layer34, a first source drain layer35, a first planarization layer36, a second source drain layer37, and a second planarization layer38. The through holes include a gate insulating through hole1121, a dielectric through hole1122, a first planarization through hole115, and a second planarization through hole116.

The active layer31, the gate insulating layer32, and the gate layer33are sequentially provided on the upper surface of the buffer layer2. The gate insulating layer32forms the gate insulating through hole1121which is disposed opposite to the buffer through hole111.

The dielectric layer34is disposed on upper surfaces of the gate insulating layer32and the gate layer33, and the dielectric layer34forms the dielectric through hole1122. The dielectric through hole1122is disposed opposite to the gate insulating through hole1121, and the gate insulating through hole1121is disposed opposite to the buffer through hole111.

The first source drain layer35is disposed on an upper surface of the dielectric layer34, a hole wall of the dielectric through hole1122, a hole wall of the gate insulating through hole1121, a hole wall of the buffer layer hole111, and side walls and a bottom surface of the second substrate recess110.

The first planarization layer36is disposed on upper surfaces of the first source and drain layer35and the dielectric layer34. The first planarization layer36forms the first planarization through hole115. The first planarization layer36fills the first recess120. The first planarization layer36fills the second substrate recess110, the buffer through hole111, the gate insulating through hole1121, and the dielectric through hole1122.

The second source drain layer37is disposed on an upper surface of the first planarization layer36and is connected to the first source drain layer35. The second planarization layer38is provided on upper surfaces of the second source drain layer37and the first planarization layer36. The second planarization layer38forms the second planarization through hole116that is disposed opposite the first planarization through hole115.

It should be noted that the first source drain layer35is disposed on the upper surface of the dielectric layer34in the display area100and the transition area200. The first source drain layer35is disposed on the sidewalls and the bottom surface of the first recess120in the bending area300. The first planarization layer36fills the first recess120. The second source drain layer37is disposed on the upper surface of the first planarization layer36in the transition area200and is connected to the first source drain layer35. The second source drain layer37is disposed on the upper surface of the first planarization layer36in the bending area300. Further, the first source drain layer35extends from the transition area200to the bending region300, the second source drain layer37extends from the transition area200to the bending area300, and the second source drain layer37is electrically connected to the first source drain layer35to implement a dual source drain trace (SD) to improve a performance of the display panel.

The first electrode4is provided on the upper surface of the array substrate3, and the first electrode4is an anode made of indium tin oxide (ITO), silver (Ag) or the like.

The pixel defining layer5is provided on upper surfaces of the first electrode4and the array substrate3. A pixel defining through hole113is formed in the pixel defining layer5of the transition area200, which is disposed opposite to the second planarization through hole116. A material of the pixel defining layer5includes, but is not limited to, polyimide, and a thickness thereof is preferably 1 um to 2 um.

The support layer6is provided on the upper surface of the pixel defining layer5. A support through hole114is formed in the support layer6of the transition area200, which is disposed opposite to the pixel defining through hole113. A material of the support layer6includes, but is not limited to, polyimide, and the thickness thereof is preferably 1 um to 2 um.

The light emitting layer7is provided on the upper surfaces of the first electrode4and the pixel defining layer5. A material of the light emitting layer7is an organic light emitting material, and the thickness thereof is preferably 0.2 μm to 0.5 μm.

The second electrode8is provided on the upper surfaces of the light emitting layer7and the pixel defining layer5. The second electrode8is a cathode.

The thin film encapsulation layer9is provided on upper surfaces of the second electrode8and the pixel defining layer5. The thin film encapsulation layer9fills the first planarization through hole115, the second planarization through hole116, the pixel defining through hole113, and the support through hole114. The thin film encapsulation layer9includes a first inorganic layer91, an organic layer92, and a second inorganic layer93. The first inorganic layer91is provided on the upper surfaces of the second electrode8and the pixel defining layer5. The material of the first inorganic layer91includes transparent oxide, fluoride, and silicon nitride, has a thickness of 0.5 um to 2 um, and has water-blocking oxygen resistance. The organic layer92is provided on the upper surface of the first inorganic layer91, and the material thereof is preferably an acryl material, and the thickness thereof is 6 um to 10 um. The second inorganic layer93is provided on the upper surface of the organic layer92, and the material thereof comprises transparent oxide, fluoride and silicon nitride, and has a thickness of 0.5 um to 2 um, and has water-blocking oxygen property.

As shown inFIG. 2toFIG. 3, in the embodiment, the first recess120is disposed in the bending area300, and the second recess121is disposed in the transition area200. The first recess120penetrates through the dielectric layer34, the gate insulating layer32, and the buffer layer2, and is recessed on a surface of a side of the flexible substrate1. Specifically, the first recess120includes a second substrate recess110, a buffer through hole111, a gate insulating through hole1121, and a dielectric through hole1122. Therefore, the first recess120is filled with the first planarization layer36. In the process of disposing the first recess120, the thickness of the second substrate13located in the bending area300is smaller than the thickness of the second substrate13of the display area100or the transition area200. This is equivalent to thinning the thickness of the second substrate13located in the bending area300. Since an elastic modulus of the second substrate13is relatively large, the display panel has better bending characteristics.

Specifically, when the display panel is bent, a neutral layer301is formed in the bending area300. Since the thickness of the second substrate13located in the bending area300is thinned, the neutral layer301moves upward and approaches the second source drain layer37, thereby reducing the bending stress of the second source drain layer37. The risk of disconnection of the traces of the second source drain layer37is prevented, and the bending characteristics of the display panel are improved, thereby improving the yield of the display panel. In addition, most of the first source drain layer35is disposed on the upper surface of the second substrate13, and the first substrate11and the second substrate13have good flexibility. Therefore, the risk of disconnection of the traces of the first source drain layer35can be prevented, and the yield of the display panel can be improved.

In the prior art, referring toFIG. 1, a single-layer first source drain electrode35is disposed in the display panel, and an organic filling layer (ODH)101is disposed at a position corresponding to the buffer layer2and the gate insulating layer32located in the bending area, this improves the flexibility of the bending area, thereby reducing the stress generated after the bending area is bent. However, during the bending process of the display panel, the generated neutral layer301is away from the first source drain layer35, which easily causes the trace of the first source and drain layer35to be easily broken, thereby affecting bending characteristics of the display panel. However, in this embodiment, a double-layer source drain layer is used, and the second substrate located in the bending area is thinned, such that the neutral layer is close to the second source drain layer, thereby further improving the flexibility of the bending area, reducing the stress generated after the bending area is bent, improving the bending characteristics of the display panel, reducing the risk of disconnection, and increasing the service life of the display panel.

It should be noted that the neutral layer in the embodiment refers to a position where the display panel is neither subjected to compressive stress nor tensile stress when bent, where the bending stress is zero. The closer the metal trace (source drain) is to the neutral plane, the less likely it is to break after the bend zone is bent.

As shown inFIGS. 2 to 3, the second recess121is disposed in the transition area200, and the second recess121penetrates through the support layer6, the pixel defining layer5, the second planarization layer38, and the first planarization layer37. Specifically, the second recess121includes a first planarization through hole115, a second planarization through hole116, a pixel defining through hole113, and a support through hole114. The second recess121is filled with the thin film encapsulation layer9. In the process of disposing the second recess121, the dam existing in the prior art is removed. The subsequently formed organic layer92is blocked by the first planarization layer36, the second planarization layer38, the pixel defining layer5, and the support layer6located in the transition area200to prevent the organic material from overflowing. Compared with the prior art, the embodiment removes the dam and shortens the width of the transition area200, thereby facilitating the display panel to achieve a narrow frame and further increasing a screen ratio of the display panel.

An embodiment of the present invention provides a display panel. On one hand, the first recess is disposed in the bending area, which can improve the bending characteristics of the display panel, reduce the risk of disconnection, and increase the service life. On Another hand, by providing the second recess in the transition area, the width of the transition area can be shortened, thereby enabling the display panel to achieve an ultra-narrow frame.

As shown inFIG. 4, the embodiment provides a method for preparing a display panel, which includes the following steps S1to S9.

As shown inFIG. 5, S1a flexible substrate preparation step is performed to prepare a flexible substrate. The flexible substrate includes the following steps S11to S13.

Specifically, In S11, a first substrate preparation step is performed to apply a polyimide solution on a surface of a glass cover to form a first substrate having a thickness of 10 um. In S12, an insulating layer preparation step, an insulating layer is prepared on an upper surface of the first substrate, and the insulating layer is made of a material having water absorption properties such as silicon nitride (SiNx) or silicon oxide (SiOx). In S13, a second substrate preparation step is performed to coat a polyimide solution on the upper surface of the insulating layer to form a second substrate, wherein the second substrate forms a second substrate recess, and the second substrate recess is located at the bending area of the display panel. The thickness of the second substrate located in the bending area is less than the thickness of the second substrate located in the display area or transition area. The second substrate located in the bending area has a thickness of 2 um to 8 um, preferably 4 um, 5 um, and 6 um. The thickness of the second substrate located in the display area and the thickness of the second substrate located in the transition area are 10 um.

In S2, a buffer layer preparation step, a buffer layer is formed on the upper surface of the flexible substrate, and the buffer layer forms a buffer through hole. The buffer through hole is opposite to the second substrate recess.

As shown inFIG. 6, in S3, an array substrate preparation step, an array substrate is prepared on the upper surface of the buffer layer, and the array substrate forms a through hole. The array substrate preparation step includes steps S31to S38.

In S31, an active layer preparation step, an active layer is prepared on the upper surface of the buffer layer by chemical vapor deposition (CVD).

In S32, a gate insulating layer preparation step, a gate insulating layer is formed on an upper surface of the active layer by a CVD process, the gate insulating layer forms a gate insulating through hole, and the gate insulating through hole is disposed opposite to the buffer through hole.

In S33, a gate layer preparation step is performed by using a physical vapor deposition (PVD) process to prepare a gate layer on the upper surface of the gate insulating layer.

In S34, a dielectric layer preparation step is performed by using a CVD process to form a dielectric layer on the upper surfaces of the first gate insulating layer and the gate layer, the dielectric layer forms a dielectric through hole, and the dielectric through hole is disposed opposite to the gate insulating through hole.

In S35, a first source drain layer preparation step is performed by using a PVD process to prepare a first source drain layer, wherein the first source drain layer is disposed on an upper surface of the dielectric layer, a hole wall of the dielectric through hole, a hole wall of the gate insulating through hole, a hole wall of the buffer through hole, and sidewalls and a bottom surface of the second substrate recess.

In S36, a first planarization layer preparation step is performed by preparing a first planarization layer on the first source drain layer and an upper surface of the dielectric layer by a PVD process, wherein the first planarization layer forms a first planarization through hole. The first planarization layer fills the second substrate recess, the buffer through hole, the gate insulating through hole, and the dielectric through hole.

In S37, a second source drain layer preparation step is performed to prepare a second source drain layer on the upper surface of the first planarization layer.

In S38, a second planarization layer preparation step is performed to prepare a second planarization layer on the upper surfaces of the second source drain layer and the first planarization layer. The second planarization layer forms a second planarization through hole that is disposed opposite the first planarization through hole.

In S4, a first electrode preparation step is performed to prepare a first electrode on the upper surface of the array substrate.

In S5, a pixel defining layer preparation step is performed to deposit a polyimide material on the first electrode and the upper surface of the array substrate by a CVD process to form a pixel defining layer. The pixel defining layer forms a pixel defining through hole that is disposed opposite to the second planarization through hole. A thickness of the pixel defining layer is preferably 1 um to 2 um.

In S6, a support layer preparation step is performed by depositing a polyimide material on the upper surface of the pixel defining layer by a CVD process to form a support layer. The support layer forms a support through hole that is disposed opposite to the pixel defining through hole.

In S7, a light emitting layer preparation step is performed to deposit an organic light emitting material on the upper surface of the first electrode and the pixel defining layer to form a light emitting layer, and the thickness thereof is preferably 0.2 um to 0.5 um.

In S8, a second electrode preparation step is performed by preparing a second electrode on the light emitting layer and the upper surface of the pixel defining layer.

As shown inFIG. 7, in S9, a thin film encapsulation layer preparation step is performed to prepare a thin film encapsulation layer on the light emitting layer, the pixel defining layer, and the upper surface of the second electrode. The thin film encapsulation layer fills the first planarization through hole, the second planarization through hole, the pixel defining through hole, and the support through hole. The thin film encapsulation layer preparation step includes the following steps S91to S93.

In S91, a first inorganic layer preparation step is performed by depositing an inorganic material on the upper surface of the second electrode and the pixel defining layer by a CVD process to form a first inorganic layer. The first inorganic layer extends to the support layer. The material of the first inorganic layer includes a transparent oxide, a fluoride, and a silicon nitride. The first inorganic layer has a thickness of 0.5 um to 2 um and has water-blocking oxygen properties.

In S92, an organic layer preparation step is performed by ink-jet printing (IJP) the organic material on the upper surface of the first inorganic layer to form an organic layer having a thickness of 6 um to 10 um.

In S93, a second inorganic layer preparation step is performed by depositing an inorganic material on the upper surface of the organic layer by a CVD process to form a second inorganic layer. The second inorganic layer extends to the upper surfaces of the first inorganic layer and the support layer. The material of the second inorganic layer includes transparent oxide, fluoride, and silicon nitride. The second inorganic layer has a thickness of 0.5 um to 2 um and has water-blocking oxygen property.

In this embodiment, the through holes includes the gate insulating through hole, the dielectric through hole, the first planarization through hole, and the second planarization through hole. The second substrate recess is disposed opposite to the buffer through hole, the gate insulating through hole, and the dielectric through hole. The first planarization through hole is disposed opposite to the second planarization through hole, the pixel defining layer, and the support through hole.

Further, the second substrate recess, the buffer through hole, the gate insulating through hole, and the dielectric through hole form the first recess. The first recess is disposed in the bending area of the display panel. In this embodiment, the first recess is filled by the first planarization layer. In the process of disposing the first recess, the thickness of the second substrate located in the bending area is smaller than the thickness of the second substrate of the display area or the transition area. This is equivalent to thinning the thickness of the second substrate located in the bending area. Since the elastic modulus of the second substrate is relatively large, the display panel has better bending characteristics.

Specifically, when the display panel is bent, the neutral layer is formed in the bending area. Since the thickness of the second substrate located in the bending area is thinned, the neutral layer moves upward and approaches the second source drain layer, thereby reducing the bending stress of the second source drain layer. The risk of disconnection of the traces of the second source drain layer is prevented, and the bending characteristics of the display panel are improved, thereby improving the yield of the display panel. In addition, most of the first source drain layer is disposed on the upper surface of the second substrate, and the first substrate and the second substrate have good flexibility. Therefore, the risk of disconnection of the traces of the first source and drain layers can be prevented, and the yield of the display panel can be improved.

The second recess includes a first planarization through hole, a second planarization through hole, a pixel defining through hole, and a support through hole to form the second recess. The second recess is disposed in the transition area of the display panel. In the embodiment, the dam existing in the prior art is removed. The subsequently formed organic layer is blocked by the first planarization layer, the second planarization layer, the pixel defining layer, and the support layer located in the transition area to prevent the organic material from overflowing. Compared with the prior art, the embodiment removes the dam and shortens the width of the transition area, thereby facilitating the display panel to achieve a narrow frame and further increasing a screen ratio of the display panel.

An embodiment of the present invention provides a display panel. On one hand, the first recess is disposed in the bending area, which can improve the bending characteristics of the display panel, reduce the risk of disconnection, and increase the service life. On Another hand, by providing the second recess in the transition area, the width of the transition area can be shortened, thereby enabling the display panel to achieve an ultra-narrow frame and further increase a screen ratio of the display panel.

The embodiment further provides a display device including the display panel as described above and a preparation method thereof. The display device can be any product or component having display function such as electronic paper, mobile phone, tablet computer, television, display, notebook computer, digital photo frame, navigator and the like. The display device improves the performance of the display device by realizing a display panel of an ultra-narrow frame, thereby improving the user experience.

In summary, although the preferable embodiments of the present disclosure have been disclosed above. It should be noted that those of ordinary skill in the art can make a variety of improvements and substitutions on the premise of not deviating from the technical principle of the present disclosure, and these improvements and substitutions should be encompassed within the protection scope of the present disclosure.