Flexible TFT substrate, flexible display panel and flexible display device

Abstract

The embodiments of the present application provide a flexible TFT substrate, a flexible display panel, and a flexible display device. The flexible TFT substrate provided by the embodiments of the present application has a recessed structure in the binding area and an organic material in the recessed structure. When the binding area of ​​the flexible TFT substrate is bent, the organic material in the recessed structure can play a role in buffering stress, thereby preventing the flexible TFT substrate from being damaged or broken, etc., especially when the bending position directly corresponds to the recessed structure, the stress generated by the bending is concentrated in the organic material in the recessed structure. Since the organic material has good bending resistance, the bending resistance of the flexible TFT substrate can be improved; when the binding area is bent, the width of the binding area can be reduced, thereby reducing the border width of the flexible display panel including the flexible TFT substrate, and realizing a narrow border design.

Description

Technical Field

[0001] The present application relates to the field of display, and in particular to a flexible TFT substrate, a flexible display panel and a flexible display device. Background Art

[0002] With the development of display devices, people have higher and higher requirements for the appearance of display devices. Compared with wide-border display devices, narrow-border display devices have better visual effects and can make users feel more immersed and the pictures are more direct and shocking. In addition, when a large screen is spliced ​​with multiple display screens, the narrow-border display screens can be almost seamlessly connected, thereby achieving a better splicing effect. Therefore, narrow-border display devices have gradually become the development trend of future display devices.

[0003] At present, the narrow-frame display products of flexible display panels are usually realized in the following manner: the binding area located at the edge of the flexible display panel is bent to reduce the width of the binding area. Since the width of the binding area is an important factor in determining the width of the display panel frame, when the width of the binding area is reduced, the frame of the flexible display panel will also be reduced, thereby realizing a narrow-frame design. However, in the process of bending the binding area of ​​the flexible display panel, the panel is easily damaged or broken. Summary of the invention

[0004] The embodiments of the present application provide a flexible TFT substrate, a flexible display panel, and a flexible display device. The flexible TFT substrate can be applied to the flexible display panel to enable the flexible display panel to achieve a narrow frame design, and the flexible TFT substrate has good anti-bending performance, thereby improving the anti-bending performance of the flexible display panel including the flexible TFT substrate.

[0005] In a first aspect, an embodiment of the present application provides a flexible TFT substrate, wherein a display area and a binding area are defined on the flexible TFT substrate, wherein the binding area is arranged at the periphery of the display area, wherein the display area includes a TFT area, wherein a thin film transistor is arranged in the TFT area, wherein a recess structure is arranged in the binding area, and wherein an organic material is arranged in the recess structure.

[0006] In some embodiments, the flexible TFT substrate includes a first flexible substrate, a first barrier layer, a second flexible substrate, a first adhesive layer, a second barrier layer, a second adhesive layer, a buffer layer, a semiconductor layer, a gate insulating layer, a gate, an interlayer dielectric layer, and a conductive layer stacked in sequence;

[0007] Among them, the conductive layer includes a source and a drain located in the TFT area; the semiconductor layer includes an active layer located in the TFT area, the active layer and the gate are arranged correspondingly, the active layer includes a channel area and a source contact area and a drain contact area located at both ends of the channel area, the source is electrically connected to the source contact area via a source contact hole located on the interlayer dielectric layer, the drain is electrically connected to the drain contact area via a drain contact hole located on the interlayer dielectric layer, and the gate, the active layer, the source and the drain together constitute the thin film transistor.

[0008] In some embodiments, the recessed structure includes a first groove, the first groove passes through the interlayer dielectric layer, the buffer layer, the second adhesive layer, the second barrier layer and the first adhesive layer, and the bottom of the first groove is a side surface of the second flexible substrate away from the first barrier layer.

[0009] In some embodiments, the recessed structure includes a second groove, which passes through the interlayer dielectric layer, the buffer layer, the second adhesive layer, the second barrier layer, the first adhesive layer, the second flexible substrate and the first barrier layer, and the bottom of the second groove is a side surface of the first flexible substrate facing the first adhesive layer.

[0010] In some embodiments, the display area also includes a capacitor area, the conductive layer also includes a first storage capacitor electrode located in the capacitor area, the semiconductor layer includes a second storage capacitor electrode located in the capacitor area, and the first storage capacitor electrode and the second storage capacitor electrode are arranged correspondingly to form a first storage capacitor between the first storage capacitor electrode and the second storage capacitor electrode.

[0011] In some embodiments, a metal layer is provided between the second adhesive layer and the buffer layer, the metal layer includes a shading member located in the TFT area and a third storage capacitor electrode located in the capacitor area, the shading member is provided corresponding to the active layer to shield the active layer, the third storage capacitor electrode is an ion-doped semiconductor material, the third storage capacitor electrode is provided corresponding to the second storage capacitor electrode, so that a second storage capacitor is formed between the third storage capacitor electrode and the second storage capacitor electrode.

[0012] In some embodiments, the material of the first barrier layer includes silicon oxide, the material of the first bonding layer includes silicon oxide, the material of the second barrier layer includes silicon nitride, and the material of the second bonding layer includes silicon oxide.

[0013] In some embodiments, a connector is provided on the surface of the binding area, the connector is used to connect to a circuit board, the connector is arranged corresponding to the recessed structure and is disposed above the organic material, and the connector is electrically connected to the thin film transistor.

[0014] In some embodiments, a plurality of the recessed structures are arranged in sequence on the binding area in a direction from the display area to the binding area.

[0015] In some embodiments, among the plurality of recessed structures arranged in sequence, the connecting member is correspondingly disposed above the recessed structure farthest from the display area.

[0016] In some embodiments, the organic material disposed within the recessed structure includes polyimide.

[0017] In a second aspect, an embodiment of the present application provides a flexible display panel, including:

[0018] A flexible TFT substrate, wherein the flexible TFT substrate is the flexible TFT substrate as described above;

[0019] A light emitting device is electrically connected to the thin film transistor in the flexible TFT substrate.

[0020] In a third aspect, an embodiment of the present application provides a flexible display device, comprising the flexible display panel as described above.

[0021] The flexible TFT substrate provided in the embodiment of the present application has a recessed structure in the binding area and an organic material in the recessed structure. When the binding area of ​​the flexible TFT substrate is bent, the organic material in the recessed structure can buffer the stress and avoid damage or breakage of the flexible TFT substrate. In particular, when the bending position directly corresponds to the recessed structure, the stress generated by the bending is concentrated in the organic material in the recessed structure. Since the organic material has good bending resistance, the bending resistance of the flexible TFT substrate can be improved. When the binding area is bent, the width of the binding area can be reduced, thereby reducing the border width of the flexible display panel including the flexible TFT substrate, thereby realizing a narrow border design. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0023] Figure 1A schematic diagram of the first structure of a flexible TFT substrate provided in an embodiment of the present application.

[0024] Figure 2 A second structural schematic diagram of the flexible TFT substrate provided in an embodiment of the present application.

[0025] Figure 3 A schematic diagram of the first structure of a flexible display panel provided in an embodiment of the present application.

[0026] Figure 4 A second structural schematic diagram of the flexible display panel provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0028] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of a first structure of a flexible TFT substrate provided in an embodiment of the present application, Figure 2 A second structural schematic diagram of a flexible TFT substrate provided in an embodiment of the present application. The embodiment of the present application provides a flexible TFT substrate 100, on which a display area and a binding area are defined, the binding area is arranged at the periphery of the display area, the display area includes a TFT area, a thin film transistor is arranged in the TFT area, a recessed structure 10 is arranged in the binding area, and an organic material 15 is arranged in the recessed structure 10.

[0029] It is understood that the binding area refers to an area on the flexible TFT substrate 100 for connecting with the circuit board, and is usually located at the edge of the flexible TFT substrate 100. Exemplarily, the circuit board may be a chip on film (COF).

[0030] Exemplarily, the number of the recessed structures 10 provided in the binding area may be one or more.

[0031] It should be noted that the flexible TFT substrate 100 of the embodiment of the present application is provided with a recessed structure 10 in the binding area, and an organic material 15 is filled in the recessed structure 10. When the binding area of ​​the flexible TFT substrate 100 is bent, the organic material 15 in the recessed structure 10 can play a role in buffering stress, thereby preventing the flexible TFT substrate 100 from being damaged or broken, etc., especially when the bending position directly corresponds to the recessed structure 10, the stress generated by the bending is concentrated in the organic material 15 in the recessed structure 10. Since the organic material 15 has good bending resistance, the bending resistance of the flexible TFT substrate 100 can be improved; when the binding area is bent, the width of the binding area can be reduced, thereby reducing the border width of the flexible display panel 200 including the flexible TFT substrate 100, thereby realizing a narrow border design.

[0032] Please combine Figure 1 and Figure 2 A connector 19 is provided on the surface of the binding area. The connector 19 is used to connect the circuit board. The connector 19 is provided corresponding to the recessed structure 10 and is provided above the organic material 15. The connector 19 is electrically connected to the thin film transistor.

[0033] Please combine Figure 1 and Figure 2 The flexible TFT substrate 100 may include a first flexible substrate 21, a first barrier layer 22, a second flexible substrate 23, a first adhesive layer 24, a second barrier layer 25, a second adhesive layer 26, a buffer layer 28, a semiconductor layer 30, a gate insulating layer 39, a gate 41, an interlayer dielectric layer 49 and a conductive layer 50 which are sequentially stacked;

[0034] Among them, the conductive layer 50 includes a source 52 and a drain 51 located in the TFT area; the semiconductor layer 30 includes an active layer 31 located in the TFT area, the active layer 31 and the gate 41 are arranged correspondingly, the active layer 31 includes a channel area and a source contact area and a drain contact area located at both ends of the channel area, the source 52 is electrically connected to the source contact area via a source contact hole located on the interlayer dielectric layer 49, the drain 51 is electrically connected to the drain contact area via a drain contact hole located on the interlayer dielectric layer 49, and the gate 41, the active layer 31, the source 52 and the drain 51 together constitute a thin film transistor.

[0035] Exemplarily, the material of the semiconductor layer 30 is an oxide semiconductor. In some embodiments, the material of the semiconductor layer 30 may include one or more of indium gallium zinc oxide (IGZO), zinc tin oxide (ZTO), and indium tin zinc oxide (ITZO). In the embodiments of the present application, multiple refers to two or more, such as three, four, five, six, etc.

[0036] Exemplarily, the source contact region and the drain contact region in the active layer 31 are both ion-doped regions, the doped ions in the ion-doped regions may be N-type ions (such as phosphorus ions and arsenic ions), and the channel region is a non-doped region.

[0037] Exemplarily, the material of the first flexible substrate 21 and the material of the second flexible substrate 23 are both polymer materials, such as polyimide (PI).

[0038] Please combine Figure 1 and Figure 2 , the recessed structure 10 may include one or more of the first groove 11 and the second groove 12. That is to say, when the number of the recessed structure 10 in the binding area is one, the recessed structure 10 may be the first groove 11 or the second groove 12; when the number of the recessed structures 10 in the binding area is multiple, the multiple recessed structures 10 may all be the first groove 11, or the multiple recessed structures 10 may all be the second groove 12, or the multiple recessed structures 10 may include the first groove 11 and the second groove 12.

[0039] Please combine Figure 1 The first groove 11 can penetrate the interlayer dielectric layer 49, the buffer layer 28, the second adhesive layer 26, the second barrier layer 25 and the first adhesive layer 24, and the bottom of the first groove 11 is a side surface of the second flexible substrate 23 away from the first barrier layer 22.

[0040] It can be understood that since the interlayer dielectric layer 49, buffer layer 28, second bonding layer 26, second barrier layer 25 and first bonding layer 24 penetrated by the first groove 11 are all inorganic layers, the first groove 11 can be formed by a single etching process, and the manufacturing process is relatively simple and low-cost.

[0041] Please combine Figure 2 The second groove 12 can penetrate the interlayer dielectric layer 49, the buffer layer 28, the second adhesive layer 26, the second barrier layer 25, the first adhesive layer 24, the second flexible substrate 23 and the first barrier layer 22, and the bottom of the second groove 12 is the side surface of the first flexible substrate 21 facing the first adhesive layer 24.

[0042] It can be understood that, since the second groove 12 penetrates all inorganic layers (interlayer dielectric layer 49, buffer layer 28, second adhesive layer 26, second barrier layer 25, first adhesive layer 24, and first barrier layer 22) in the binding area of ​​the flexible TFT substrate 100, and penetrates the second flexible substrate 23, at the location of the second groove 12, only the first flexible substrate 21 and the organic material 15 located above the first flexible substrate 21 are provided on the flexible TFT substrate 100. Since both the first flexible substrate 21 and the organic material 15 have strong bending resistance, when the bending position of the flexible TFT substrate 100 corresponds to the second groove 12, the bending-resistant material (first flexible substrate 21 and organic material 15) at this position can effectively buffer the bending stress and avoid damage or breakage of the flexible TFT substrate 100.

[0043] It is understandable that due to Figure 1 The first groove 11 in the structure penetrates through five structural layers (interlayer dielectric layer 49, buffer layer 28, second bonding layer 26, second barrier layer 25 and first bonding layer 24), and Figure 2 The second groove 12 in the embodiment of the present invention penetrates through seven structural layers (interlayer dielectric layer 49, buffer layer 28, second bonding layer 26, second barrier layer 25, first bonding layer 24, second flexible substrate 23 and first barrier layer 22), that is, Figure 1 Compared with the first groove 11, Figure 2 The second groove 12 penetrates more structural layers, that is, the second groove 12 is deeper. Since the first groove 11 and the second groove 12 are both filled with organic materials, and the organic material can buffer the stress when being bent, the second groove 12 has better bending resistance than the first groove 11.

[0044] In some embodiments, the recessed structure 10 may also be a through hole, which passes through the interlayer dielectric layer 49, the buffer layer 28, the second adhesive layer 26, the second barrier layer 25, the first adhesive layer 24, the second flexible substrate 23, the first barrier layer 22 and the first flexible substrate 21, and an organic material is provided in the through hole.

[0045] Please combine Figure 2 , a plurality of recessed structures 10 arranged in sequence may be provided on the binding area in the direction from the display area to the binding area. It can be understood that by providing a plurality of recessed structures 10 arranged in sequence, the bending stress can be sequentially transmitted between the plurality of recessed structures 10, that is, the stress generated by bending can be dispersed by means of the plurality of recessed structures 10. Compared with the solution of providing only one recessed structure 10 in the direction from the display area to the binding area on the binding area, the solution of the plurality of recessed structures 10 can better improve the anti-bending performance of the flexible TFT substrate 100.

[0046] In the embodiment of the present application, a plurality refers to two or more than two, for example, three, four, five, six, seven, eight, etc.

[0047] In some embodiments, among the plurality of recessed structures 10 arranged in sequence, the connecting member 19 is correspondingly disposed above the recessed structure 10 farthest from the display area. In this way, when the flexible TFT substrate 100 is bent, the bending position can be set to correspond to other recessed structures 10 closer to the display area, thereby avoiding the occurrence of the situation where the connecting member 19 is damaged or falls off from the flexible TFT substrate 100 when the bending position is set to correspond to the connecting member 19.

[0048] Please combine Figure 2 It can be understood that when a plurality of recessed structures 10 are arranged in sequence on the binding area in the direction from the display area to the binding area in the flexible TFT substrate 100, and the plurality of recessed structures 10 are all second grooves 12, the strong bending resistance of the second grooves 12 and the dispersion effect of the plurality of second grooves 12 on the bending stress can be utilized to maximize the bending resistance of the flexible TFT substrate 100.

[0049] Please combine Figure 1 and Figure 2 The display area also includes a capacitor area, the conductive layer 50 also includes a first storage capacitor electrode 53 located in the capacitor area, the semiconductor layer 30 includes a second storage capacitor electrode 32 located in the capacitor area, the first storage capacitor electrode 53 and the second storage capacitor electrode 32 are arranged correspondingly, so that a first storage capacitor is formed between the first storage capacitor electrode 53 and the second storage capacitor electrode 32.

[0050] It can be understood that the first storage capacitor electrode 53 is electrically connected to the source electrode 52 , so that the first storage capacitor can charge the thin film transistor to maintain the thin film transistor in an on state.

[0051] Please combine Figure 1 and Figure 2 A metal layer 70 is provided between the second adhesive layer 26 and the buffer layer 28. The metal layer 70 includes a shading member 71 located in the TFT area and a third storage capacitor electrode 72 located in the capacitor area. The shading member 71 is provided corresponding to the active layer 31 to shield the active layer 31. The third storage capacitor electrode 72 is an ion-doped semiconductor material. The third storage capacitor electrode 72 is provided corresponding to the second storage capacitor electrode 32, so that a second storage capacitor is formed between the third storage capacitor electrode 72 and the second storage capacitor electrode 32.

[0052] It is understandable that the third storage capacitor electrode 72 is electrically connected to the source electrode 52, so that the second storage capacitor can charge the thin film transistor to maintain the on state of the thin film transistor. In the embodiment of the present application, the first storage capacitor and the second storage capacitor are simultaneously provided to charge the thin film transistor, so as to reduce or eliminate the influence of leakage on the thin film transistor.

[0053] Please combine Figure 1 and Figure 2 The connector 19 may be a part of the conductive layer 50, that is, the conductive layer 50 may include a source 52 and a drain 51 located in the TFT region, a first storage capacitor electrode 53 located in the capacitor region, and a connector 19 located in the binding region.

[0054] Exemplarily, the source electrode 52 may also be electrically connected to the light shielding member 71 through vias disposed on the interlayer dielectric layer 49 and the buffer layer 28 to improve the electrical performance of the thin film transistor and make the channel current more stable.

[0055] For example, the organic material 15 disposed in the recessed structure 10 may be polyimide (PI). It is understood that since polyimide has good flexibility and strong bending resistance, it can effectively buffer the stress generated by bending and improve the bending resistance of the flexible TFT substrate 100.

[0056] For example, the organic material 15 can be filled into the recessed structure 10 by coating, and then the organic material coated on the surface of the flexible TFT substrate 100 (ie, the surface of the interlayer dielectric layer 49 ) is removed by exposure and development.

[0057] For example, the material of the first barrier layer 22 is silicon oxide (SiO2), the material of the first bonding layer 24 is silicon oxide (SiO2), and the material of the second barrier layer 25 is silicon nitride (SiN x ), the material of the second bonding layer 26 is silicon oxide (SiO2).

[0058] It can be understood that by setting the material of the first barrier layer 22 between the first flexible substrate 21 and the second flexible substrate 23 to be silicon oxide, not only can silicon oxide be used to block water, oxygen and impurity ions, but also the strong adhesion of silicon oxide can be used to improve the bonding effect between the first flexible substrate 21 and the second flexible substrate 23; in addition, by setting the first adhesive layer 24 between the second flexible substrate 23 and the second barrier layer 25, the bonding effect between the second flexible substrate 23 and the second barrier layer 25 can be improved; by setting the second adhesive layer 26 between the second barrier layer 25 and the buffer layer 28, the bonding effect between the second barrier layer 25 and the buffer layer 28 can be improved; in addition, by setting the material of the second barrier layer 25 to silicon nitride, since the water and oxygen blocking ability of silicon nitride is greater than that of silicon oxide, the water and oxygen blocking ability of the flexible TFT substrate 100 can be further improved on the basis of setting the first barrier layer 22.

[0059] For example, the material of the buffer layer 28, the material of the gate insulating layer 39, and the material of the interlayer dielectric layer 49 all include silicon nitride (SiN x ), silicon oxide (SiO x ) and silicon oxynitride (SiO x N y )

[0060] Exemplarily, the material of the gate 41 and the material of the conductive layer 50 are both metals. In some embodiments, the material of the gate 41, the material of the conductive layer 50, and the material of the metal layer 70 include one or more of molybdenum (Mo), titanium (Ti), copper (Cu), and aluminum (Al).

[0061] See also Figure 3 and Figure 4 , Figure 3 A schematic diagram of a first structure of a flexible display panel provided in an embodiment of the present application, Figure 4 A second structural schematic diagram of a flexible display panel provided in an embodiment of the present application. The embodiment of the present application also provides a flexible display panel 200, including a flexible TFT substrate 100 and a light-emitting device 61, wherein the flexible TFT substrate 100 may be the flexible TFT substrate 100 in any of the above embodiments, and the light-emitting device 61 is electrically connected to the thin film transistor in the flexible TFT substrate 100, so that the light-emitting device 61 is driven by the thin film transistor.

[0062] Please combine Figure 3 and Figure 4The flexible display panel 200 may further include a passivation layer 62, a planar layer 63, a pixel definition layer 64, an anode 66, and a cathode 65, wherein the passivation layer 62 is arranged on a side of the conductive layer 50 and the interlayer dielectric layer 49 away from the buffer layer 28, the planar layer 63 is arranged on a side of the passivation layer 62 away from the interlayer dielectric layer 49, and the pixel definition layer 64 is arranged on a side of the planar layer 63 away from the passivation layer 62, wherein an opening 641 is provided on the pixel definition layer 64, and the light-emitting device 61 is arranged in the opening 641, and the anode 66 and the cathode 65 are respectively arranged on both sides of the light-emitting device 61, wherein the anode 66 is arranged between the light-emitting device 61 and the planar layer 63, and the anode 66 is connected to the source 52 through a via located on the planar layer 63 and the passivation layer 62, and the cathode 65 is arranged on a side of the light-emitting device 61 away from the anode 66.

[0063] Exemplarily, the light emitting device 61 is an OLED (Organic Light-Emitting Diode) device. In this case, the flexible display panel 200 is a flexible OLED display panel.

[0064] Exemplarily, the material of the planarization layer 63 and the material of the pixel definition layer 64 are both organic materials, such as organic photoresist materials.

[0065] For example, the material of the passivation layer 62 may include silicon nitride (SiN x ), silicon oxide (SiO x ) and silicon oxynitride (SiO x N y )

[0066] For example, the material of the anode 66 and the material of the cathode 65 may both include one or more of a transparent conductive metal oxide and a metal. For example, the transparent conductive metal oxide may be indium tin oxide (ITO), and the metal may be silver.

[0067] For example, the flexible display panel 200 can be prepared on a rigid substrate (e.g., a glass substrate). After preparation, a laser is used to irradiate the flexible display panel 200 from the side of the rigid substrate facing away from the flexible display panel 200, so that the adhesion between the flexible display panel 200 and the rigid substrate is reduced (that is, the adhesion between the first flexible substrate 21 and the rigid substrate is reduced), and then the rigid substrate is peeled off from the flexible display panel 200.

[0068] An embodiment of the present application further provides a flexible display device, comprising the flexible display panel 200 in any of the above embodiments.

[0069] Exemplarily, the flexible display device may further include a flexible circuit board, which is electrically connected to the connector 19. When the flexible display panel 200 is bent, the flexible circuit board and the binding area of ​​the flexible display panel 200 can be bent together, thereby reducing the width of the binding area of ​​the flexible display panel 200 and achieving a narrow frame design.

[0070] Exemplarily, the flexible circuit board may be a chip on film.

[0071] Exemplarily, the flexible display device can be a television, a mobile phone, a computer monitor, a tablet computer, an advertising display screen, a gaming device, an augmented reality (AR) device, a virtual reality (VR) device, a data storage device, an audio playback device, a video playback device, a wearable device, or other device with a display screen, wherein the wearable device can be a smart bracelet, smart glasses, a smart watch, smart decoration, etc.

[0072] The flexible TFT substrate, flexible display panel and flexible display device provided in the embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A flexible TFT substrate, characterized in that: The flexible TFT substrate is defined with a display area and a binding area, wherein the binding area is arranged at the periphery of the display area, the display area includes a TFT area, a thin film transistor is arranged in the TFT area, a recessed structure is arranged in the binding area, and an organic material is arranged in the recessed structure; The flexible TFT substrate comprises a first flexible substrate, a first barrier layer, a second flexible substrate, a first adhesive layer, a second barrier layer, a second adhesive layer, a buffer layer, a semiconductor layer, a gate insulating layer, a gate, an interlayer dielectric layer and a conductive layer which are sequentially stacked, wherein the conductive layer comprises a source electrode and a drain electrode located in the TFT region; the semiconductor layer comprises an active layer located in the TFT region; The recessed structure comprises a first groove, the first groove penetrates the interlayer dielectric layer, the buffer layer, the second adhesive layer, the second barrier layer and the first adhesive layer, and the bottom of the first groove is a side surface of the second flexible substrate away from the first barrier layer; And / or, the recessed structure includes a second groove, the second groove passes through the interlayer dielectric layer, the buffer layer, the second adhesive layer, the second barrier layer, the first adhesive layer, the second flexible substrate and the first barrier layer, and the bottom of the second groove is a side surface of the first flexible substrate facing the first adhesive layer.

2. The flexible TFT substrate according to claim 1, characterized in that: The active layer and the gate are arranged correspondingly, the active layer includes a channel region and a source contact region and a drain contact region located at both ends of the channel region, the source is electrically connected to the source contact region via a source contact hole located on the interlayer dielectric layer, the drain is electrically connected to the drain contact region via a drain contact hole located on the interlayer dielectric layer, and the gate, the active layer, the source and the drain together constitute the thin film transistor.

3. The flexible TFT substrate according to claim 2, characterized in that: The display area also includes a capacitor area, the conductive layer also includes a first storage capacitor electrode located in the capacitor area, the semiconductor layer includes a second storage capacitor electrode located in the capacitor area, and the first storage capacitor electrode and the second storage capacitor electrode are arranged correspondingly to form a first storage capacitor between the first storage capacitor electrode and the second storage capacitor electrode.

4. The flexible TFT substrate according to claim 3, characterized in that: A metal layer is provided between the second adhesive layer and the buffer layer, the metal layer includes a shading member located in the TFT area and a third storage capacitor electrode located in the capacitor area, the shading member is provided corresponding to the active layer to shield the active layer, the third storage capacitor electrode is an ion-doped semiconductor material, the third storage capacitor electrode is provided corresponding to the second storage capacitor electrode, so that a second storage capacitor is formed between the third storage capacitor electrode and the second storage capacitor electrode.

5. The flexible TFT substrate according to claim 2, characterized in that: The material of the first barrier layer includes silicon oxide, the material of the first bonding layer includes silicon oxide, the material of the second barrier layer includes silicon nitride, and the material of the second bonding layer includes silicon oxide.

6. The flexible TFT substrate according to claim 1, characterized in that: A connector is provided on the surface of the binding area, the connector is used to connect to a circuit board, the connector is arranged corresponding to the recessed structure and is arranged above the organic material, and the connector is electrically connected to the thin film transistor.

7. The flexible TFT substrate according to claim 6, characterized in that: A plurality of recessed structures are arranged in sequence on the binding area in a direction from the display area to the binding area.

8. The flexible TFT substrate according to claim 7, characterized in that: Among the plurality of recessed structures arranged in sequence, the connecting member is correspondingly arranged above the recessed structure farthest from the display area.

9. The flexible TFT substrate according to any one of claims 1 to 8, characterized in that: The organic material disposed in the recessed structure includes polyimide.

10. A flexible display panel, characterized in that: include: A flexible TFT substrate, wherein the flexible TFT substrate is the flexible TFT substrate according to any one of claims 1 to 9; A light emitting device is electrically connected to the thin film transistor in the flexible TFT substrate.

11. A flexible display device, characterized in that: Comprising the flexible display panel as claimed in claim 10.

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