Display panel, method for manufacturing display panel, and electronic device

Abstract

The embodiments of the present application provide a display panel, a method for manufacturing a display panel, and an electronic device, wherein the display panel includes a bending display area, the bending display area has a bending axis, a plurality of first thin film transistors are arranged on the bending display area, each of the first thin film transistors includes a first source and a first drain, a first conductive channel is formed between the first source and the first drain of each first thin film transistor, and the angle between the direction of the first conductive channel and the bending axis is less than 90 degrees; wherein the total length of each part of the first conductive channel in the direction of the first conductive channel is greater than the total length of each part of the first conductive channel in any other direction. The above-mentioned display panel can reduce the display brightness difference between the bending display area and the non-bending display area.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display panel, a method for manufacturing a display panel, and an electronic device. Background Art

[0002] Flexible display refers to a display screen that can be bent, curved, folded or rolled up without significant damage and is made using a thin and flexible substrate, unlike a flat panel display.

[0003] With the increasing number of flexible display screens, active-matrix organic light-emitting diode (AMOLED) display panels based on low temperature polysilicon (LTPS) are widely used. However, during the bending process of the LTPS-based flexible display screen, there will be a brightness difference between the bent display area and the non-bent display area, and as the display time of the bent display area increases, the difference in display brightness between the bent display area and the non-bent display area becomes larger. Summary of the invention

[0004] The present application provides a display panel, a method for manufacturing a display panel, and an electronic device to reduce the difference in display brightness between a bent display area and a non-bent display area.

[0005] In a first aspect, the present application provides a display panel, comprising a bending display area, the bending display area having a bending axis, a plurality of first thin film transistors being arranged on the bending display area, each of the first thin film transistors comprising a first source and a first drain, a first conductive channel being formed between the first source and the first drain of each first thin film transistor, and an angle formed between the direction of the first conductive channel and the bending axis being less than 90 degrees; wherein the total length of each portion of the first conductive channel in the direction of the first conductive channel is greater than the total length of each portion of the first conductive channel in any other direction.

[0006] The above-mentioned display panel, by setting the direction of the first conductive channel of the first thin film transistor in the bent display area to have an angle less than 90 degrees with the bending axis, so that the angle between the direction of the first conductive channel and the strain direction of the first conductive channel is not 0 degrees, the strain along the direction of the first conductive channel of the first conductive channel is reduced compared to when the direction of the first conductive channel is parallel to the strain direction of the first conductive channel, the carrier mobility change in the first conductive channel is reduced, the turn-on current change of the first thin film transistor is reduced, the driving current change of the bent display area is reduced, and the display brightness difference between the bent display area and the non-bent display area is reduced, thereby improving the display effect of the display panel.

[0007] In a possible design, when the display panel is bent so that the first thin film transistor is subjected to compressive strain, an angle between a first conductive channel direction of the first thin film transistor and the bending axis is 0 to 5 degrees.

[0008] In a possible design, the angle between the first conductive channel direction of the first thin film transistor and the bending axis is 0 degrees. Through the solution provided by this embodiment, the compressive strain on the first conductive channel is perpendicular to the direction of the first conductive channel, the length of the first conductive channel in the direction of the first conductive channel does not change with the change of the compressive strain on the first conductive channel, the carrier mobility in the first conductive channel does not change with the change of the compressive strain on the first conductive channel, so that the turn-on current of the first thin film transistor does not change with the change of the compressive strain on the first conductive channel, the driving current of the bent display area is the same as the driving current of the non-bent display area, and the display brightness of the bent display area is consistent with that of the non-bent display area.

[0009] In a possible design, when the bending of the display panel causes the first thin film transistor to be subjected to tensile strain, the angle between the first conductive channel direction of the first thin film transistor and the bending axis is 65 to 75 degrees. Through the solution provided in this embodiment, the angle between the first conductive channel direction of the first thin film transistor and the bending axis is set to 65 to 75 degrees, the tensile strain on the first conductive channel is mostly perpendicular to the direction of the first conductive channel, the length of the first conductive channel in the direction of the first conductive channel changes less with the tensile strain on the first conductive channel, the carrier mobility in the first conductive channel changes less with the tensile strain on the first conductive channel, so that the turn-on current of the first thin film transistor changes less with the tensile strain on the first conductive channel, the driving current of the bent display area is less different from the driving current of the non-bent display area, and the display brightness difference between the bent display area and the non-bent display area is smaller.

[0010] In a possible design, a plurality of second thin film transistors are further provided on the bent display area, each of the second thin film transistors includes a second source and a second drain, a second conductive channel is formed between the second source and the second drain of each second thin film transistor, and the direction of the second conductive channel is consistent with the direction of the first conductive channel, wherein the total length of each part of the second conductive channel in the direction of the second conductive channel is greater than the total length of each part of the second conductive channel in any other direction. Through the solution provided in this embodiment, the direction of the second conductive channel of the second thin film transistor in the bent display area is set to be the same as the direction of the first conductive channel, thereby simplifying the manufacturing process of the thin film transistor of the display panel and saving costs.

[0011] In a possible design, both the first thin film transistor and the second thin film transistor are low temperature polysilicon thin film transistors.

[0012] In a possible design, it also includes a non-bending display area, on which a plurality of third thin film transistors are arranged, each of the third thin film transistors includes a third source and a third drain, a third conductive channel is formed between the third source and the third drain of each of the third thin film transistors, and the direction of the third conductive channel is inconsistent with the direction of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction.

[0013] In a possible design, a non-bending display area is also included, and a plurality of third thin film transistors are arranged on the non-bending display area, each of the third thin film transistors includes a third source and a third drain, and a third conductive channel is formed between the third source and the third drain of each of the third thin film transistors, and the direction of the third conductive channel is consistent with the direction of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction. Through the solution provided in this embodiment, the direction of the third conductive channel of the third thin film transistor in the non-bending display area is set to be the same as the direction of the first conductive channel, thereby simplifying the manufacturing process of the thin film transistor of the display panel and saving costs.

[0014] In a possible design, the third thin film transistor is a low temperature polysilicon thin film transistor.

[0015] In a second aspect, the present application provides an electronic device, comprising the display panel described in the first aspect.

[0016] In a third aspect, the present application provides a method for manufacturing a display panel, comprising:

[0017] Providing a substrate, wherein the substrate comprises a bending display area, and the bending display area has a bending axis;

[0018] forming a buffer layer on the substrate;

[0019] Depositing an amorphous silicon film on the buffer layer, performing polycrystallization on the amorphous silicon film to form a polycrystalline silicon film, and performing patterning on the polycrystalline silicon film to form an active layer located on the buffer layer;

[0020] forming a gate insulating layer on the patterned active layer;

[0021] forming a first metal layer on the gate insulating layer, and patterning the first metal layer to form a gate located above the active layer;

[0022] In which, in the process of forming the gate, ion implantation is performed on the active layer so that the active layer includes a first conductive channel, a first source region and a first drain region, the first conductive channel is formed between the first source region and the first drain region, the angle between the direction of the first conductive channel and the bending axis is less than 90 degrees, and the total length of each part of the first conductive channel in the direction of the first conductive channel is greater than the total length of each part of the first conductive channel in any other direction.

[0023] In the manufacturing method of the above-mentioned display panel, when manufacturing the first thin film transistor in the bent display area of ​​the display panel, the direction of the first conductive channel of the first thin film transistor in the bent display area is set to have an angle less than 90 degrees with the bending axis, so that the angle between the direction of the first conductive channel and the strain direction of the first conductive channel is not 0 degrees, and the strain along the direction of the first conductive channel of the first conductive channel is reduced compared to when the direction of the first conductive channel is parallel to the strain direction of the first conductive channel, the carrier mobility in the first conductive channel changes less, the turn-on current of the first thin film transistor changes less, the driving current of the bent display area changes less, and the display brightness difference between the bent display area and the non-bent display area is reduced, thereby improving the display effect of the display panel.

[0024] In one possible design, it also includes:

[0025] forming a gate dielectric layer on the patterned first metal layer;

[0026] forming an interlayer insulating layer on the gate dielectric layer;

[0027] forming a first via hole and a second via hole, wherein the first via hole and the second via hole respectively expose the first source region and the first drain region;

[0028] A patterned source-drain metal layer is formed, and the first source and the first drain are overlapped, wherein the source-drain metal layer includes the first source and the first drain.

[0029] In a possible design, when the bending of the substrate causes the first conductive channel to be subjected to compressive strain, an angle between the direction of the first conductive channel and the bending axis is 0 degrees to 5 degrees.

[0030] In a possible design, an angle between the first conductive channel direction and the bending axis is 0 degree.

[0031] In a possible design, when the bending of the substrate causes the first conductive channel to be subjected to tensile strain, an angle between the direction of the first conductive channel and the bending axis is 65 degrees to 75 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A curve diagram showing the variation of carrier mobility with compressive strain in an existing thin film transistor;

[0033] Figure 2 A curve diagram showing the variation of carrier mobility with tensile strain in an existing thin film transistor;

[0034] Figure 3 A schematic diagram of the structure of a display panel provided in one embodiment of the present application;

[0035] Figure 4 A schematic diagram of a first source, a first drain and a first conductive channel provided in one embodiment of the present application;

[0036] Figure 5 A schematic diagram of a first source, a first drain, and a first conductive channel provided in another embodiment of the present application;

[0037] Figure 6 A curve diagram showing the variation of carrier mobility with compressive strain in a first thin film transistor provided in an embodiment of the present application;

[0038] Figure 7 A curve diagram showing the variation of carrier mobility with tensile strain in a first thin film transistor provided in an embodiment of the present application;

[0039] Figure 8 A flowchart of a method for manufacturing a display panel provided in one embodiment of the present application;

[0040] Fig. 9 A cross-sectional view of a display panel provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0043] Thin film transistors are divided into polycrystalline silicon (poly-Si, p-Si) TFT and amorphous silicon (a-Si) TFT. The difference between the two lies in the different transistor characteristics. The molecular structure of p-Si TFT is arranged neatly and directional in a grain, so the electron mobility is 200-300 times faster than that of a-Si TFT with disordered arrangement. p-Si mainly includes high temperature polycrystalline silicon (high temperature p-Si, HTPS) and low temperature polycrystalline silicon (lowtemperature p-Si, LTPS).

[0044] LTPS technology is a process that can be applied to the new generation of TFT display screens. It mainly transforms a-Si thin film into p-Si thin film through excimer laser annealing, metal optimized crystallization or solid phase crystallization. LTPS TFT display screens have faster response time and higher resolution, so they have better picture display quality. Using LTPS technology when forming the circuit around the display device can reduce integrated circuits, simplify the periphery of the display device, and thus achieve narrow frame technology.

[0045] Flexible displays refer to displays that can be bent, curved, folded or rolled up without significant damage and are made using thin and flexible substrates, unlike flat displays. In recent years, with the development of new material technologies, the application of flexible displays to electronic devices has become a reality. Flexible displays can be used in a variety of applications such as e-paper, e-books, televisions, computers, PDAs, car displays, tablets, smartphones, and wearable devices.

[0046] With the increasing number of flexible display screens, active-matrix organic light-emitting diode (AMOLED) display panels based on LTPS are widely used. However, during the bending process of the flexible display screen based on LTPS, there will be a brightness difference between the bent display area and the non-bent display area. The applicant found that when the LTPS TFT is subjected to compressive strain, the carrier mobility of the LTPS TFT increases (such as 0.3‰ compressive strain can cause the carrier mobility to increase by 10%), and the turn-on current of the LTPS TFT increases. The increase in the turn-on current of the LTPS TFT will cause the driving current of the bent display area to increase, thereby increasing the brightness of the screen; when the LTPS TFT is subjected to tensile strain, the carrier mobility of the LTPS TFT decreases (0.3‰ tensile strain can cause the carrier mobility to decrease by 2% to 5%), the turn-on current of the LTPS TFT decreases, and the increase in the turn-on current of the LTPS TFT will cause the driving current of the bent display area to decrease, thereby reducing the brightness of the screen. And as the display time of the bent display area increases, the difference between the display brightness of the bent display area and the display brightness of the non-bent display area becomes larger.

[0047] A thin film transistor generally includes a source electrode and a drain electrode, and a conductive channel is provided between the source electrode and the drain electrode. Figure 1 The graph is a graph showing the change of carrier mobility in the thin film transistor with the amount of compressive strain applied to the thin film transistor when the thin film transistor is subjected to compressive strain and the direction of the compressive strain is parallel to the direction of the conductive channel. Figure 1 It can be seen that when the thin film transistor is subjected to compressive strain and the direction of the compressive strain is parallel to the direction of the conductive channel, the carrier mobility in the thin film transistor increases with the increase of the amount of compressive strain to which the thin film transistor is subjected. The total length of each part of the conductive channel in the conductive channel direction is greater than the total length of each part of the conductive channel in any other direction.

[0048] Figure 2 The graph is a graph showing the change of carrier mobility in the thin film transistor with the amount of tensile strain applied to the thin film transistor when the thin film transistor is subjected to tensile strain and the direction of the tensile strain is parallel to the direction of the conductive channel. Figure 2 It can be seen that when the thin film transistor is subjected to tensile strain and the direction of the tensile strain is parallel to the direction of the conductive channel, the carrier mobility in the thin film transistor decreases as the tensile strain increases.

[0049] Please refer to Figures 3 to 5, an embodiment of the present application provides a display panel, including a bending display area 20, and the bending display area 20 has a bending axis 21. A plurality of first thin film transistors 22 are arranged on the bending display area 20. Each first thin film transistor 22 includes a first source 222 and a first drain 224, and a first conductive channel 226 is formed between the first source 222 and the first drain 224 of each first thin film transistor 22. The angle between the first conductive channel direction s and the bending axis 21 is less than 90 degrees. Among them, the total length of each part of the first conductive channel 226 in the first conductive channel direction s is greater than the total length of each part of the first conductive channel 226 in any other direction.

[0050] For the scroll display panel, the scroll display panel has a length and a width. The scroll display panel can be scrolled along the bending axis in the length direction, and the bending axis is perpendicular to the length direction of the scroll display panel. In this case, each area of ​​the display panel along the length direction can be bent, and each area of ​​the display panel is a bent display area 20. Alternatively, the scroll display panel can be scrolled along the bending axis in the width direction, and the bending axis is perpendicular to the width direction of the scroll display panel. In this case, each area of ​​the display panel along the width direction can be bent, and each area of ​​the display panel is a bent display area 20.

[0051] For the foldable display panel, the bending display area 20 only occupies a part of the display panel, and the bending display area 20 has a length and a width. The foldable display panel can be folded along the bending axis in the length direction, and the bending axis is perpendicular to the length direction of the foldable display panel. Alternatively, the foldable display panel can be folded along the bending axis in the width direction, and the bending axis is perpendicular to the width direction of the foldable display panel.

[0052] It should be noted that, regardless of whether it is a roll-up display panel or a folding display panel, the bending axis of the display panel is fixed.

[0053] The bending display area 20 is an area where stress and strain are generated in various structures in the display panel when the display panel is bent along the bending axis 21. The strain direction of each structure in the display panel is perpendicular to the bending axis 21. The various structures specifically refer to that the display panel includes a substrate and thin film transistors and pixels formed on the substrate. The projection of the first conductive channel 226 on the substrate can be bent or straight. Since the angle between the first conductive channel direction s and the bending axis 21 is less than 90 degrees, the angle between the first conductive channel direction s and the strain direction of the first conductive channel 226 is not 0 degrees, that is, the first conductive channel direction s and the strain direction of the first conductive channel 226 are not parallel to each other. Figure 4 and Figure 5 The first direction x is the direction of the strain on the first thin film transistor 22 , and the second direction y is parallel to the bending axis 21 .

[0054] The mobility characterizes the speed at which carriers move in the first conductive channel 226 between the first source 222 and the first drain 224. When the first conductive channel 226 is strained along the first conductive channel direction s, the length of the first conductive channel 226 in the first conductive channel direction s changes. When the first conductive channel direction s is parallel to the strain direction of the first thin film transistor 22, the first conductive channel 226 is strained the most along the first conductive channel direction s, and the length change of the first conductive channel 226 in the first conductive channel direction s is the largest. When the first conductive channel 226 is subjected to compressive strain along the first conductive channel direction s, the length of the first conductive channel 226 in the first conductive channel direction s decreases; when the first conductive channel 226 is subjected to tensile strain along the first conductive channel direction s, the length of the first conductive channel 226 in the first conductive channel direction s increases.

[0055] When the first conductive channel direction s of the first thin film transistor 22 is not parallel to the strain direction of the first thin film transistor 22, compared with when the first conductive channel direction s is parallel to the strain direction of the first thin film transistor 22, the strain on the first conductive channel 226 along the first conductive channel direction s is reduced, the length change of the first conductive channel 226 in the first conductive channel direction s is reduced, and the carrier mobility change in the first conductive channel 226 is reduced.

[0056] The display panel may further include a non-bending display area, and the display brightness of the non-bending display area is not affected by the bending of the bent display area 20 .

[0057] The display panel of the embodiment of the present application sets the first conductive channel direction s of the first thin film transistor 22 of the bending display area 20 to form an angle less than 90 degrees with the bending axis 21, so that the angle between the first conductive channel direction s and the strain direction of the first conductive channel 226 is not 0 degrees. Compared with when the first conductive channel direction s is parallel to the strain direction of the first conductive channel 226, the strain along the first conductive channel direction s of the first conductive channel 226 is reduced, the carrier mobility change in the first conductive channel 226 is reduced, the turn-on current change of the first thin film transistor 22 is reduced, the driving current change of the bending display area 20 is reduced, and the display brightness difference between the bending display area 20 and the non-bending display area is reduced, thereby improving the display effect of the display panel.

[0058] In one embodiment, when the bending of the display panel causes the first thin film transistor 22 of the bent display area 20 to be subjected to compressive strain, the angle between the first conductive channel direction s of the first thin film transistor 22 and the bending axis 21 is 0 degrees to 5 degrees. Preferably, when the angle between the first conductive channel direction s of the first thin film transistor 22 and the bending axis 21 is 0 degrees, the compressive strain on the first conductive channel 226 is perpendicular to the first conductive channel direction s, the length of the first conductive channel 226 in the first conductive channel direction s does not change with the change of the compressive strain on the first conductive channel 226, the carrier mobility in the first conductive channel 226 does not change with the change of the compressive strain on the first conductive channel 226, so that the turn-on current of the first thin film transistor 22 does not change with the change of the compressive strain on the first conductive channel 226, the driving current of the bent display area 20 is the same as the driving current of the non-bending display area, and the display brightness of the bent display area 20 is consistent with that of the non-bending display area.

[0059] It can be understood that when the angle between the first conductive channel direction s and the bending axis 21 is 0 degrees, the angle between the first conductive channel direction s and the compressive strain on the first conductive channel 226 is 90 degrees. When the angle between the first conductive channel direction s and the bending axis 21 is 45 degrees, the angle between the first conductive channel direction s and the compressive strain on the first conductive channel 226 is 45 degrees. When the angle between the first conductive channel direction s and the bending axis 21 is 90 degrees, the angle between the first conductive channel direction s and the compressive strain on the first conductive channel 226 is 0 degrees.

[0060] See also Figure 6 , Figure 6 A curve diagram showing the change of carrier mobility in the first thin film transistor 22 with the amount of compressive strain provided in an embodiment of the present application, specifically, a curve diagram showing the change of carrier mobility in the first thin film transistor 22 with the amount of compressive strain when the first thin film transistor 22 is subjected to compressive strain and the angles between the direction of the compressive strain and the direction s of the first conductive channel are 0 degrees, 45 degrees and 90 degrees respectively. Figure 6It can be seen that when the angle between the first conductive channel direction s and the compressive strain to which the first conductive channel 226 is subjected is 0 degrees, the carrier mobility in the first conductive channel 226 increases with the increase of the compressive strain to which the first conductive channel 226 is subjected. When the angle between the first conductive channel direction s and the compressive strain to which the first conductive channel 226 is subjected is 45 degrees, the carrier mobility in the first conductive channel 226 increases with the increase of the compressive strain to which the first conductive channel 226 is subjected. When the compressive strain to which the first conductive channel 226 is subjected changes in the same amount, the carrier mobility in the first conductive channel 226 changes more when the angle between the first conductive channel direction s and the compressive strain to which the first conductive channel 226 is subjected is 0 degrees than when the angle between the first conductive channel direction s and the compressive strain to which the first conductive channel 226 is subjected is 45 degrees. When the angle between the first conductive channel direction s and the compressive strain on the first conductive channel 226 is 90 degrees, the carrier mobility in the first conductive channel 226 does not substantially change with the change in the amount of the compressive strain on the first conductive channel 226 .

[0061] In one embodiment, when the display panel is bent so that the first thin film transistor 22 of the bent display area 20 is subjected to tensile strain, the angle between the first conductive channel direction s of the first thin film transistor 22 and the bending axis 21 is 65 degrees to 75 degrees. When the bending of the display panel causes the first thin film transistor 22 of the bent display area 20 to be subjected to tensile strain, the angle between the first conductive channel direction s of the first thin film transistor 22 and the bending axis 21 is set to 65 degrees to 75 degrees, and the tensile strain borne by the first conductive channel 226 is mostly perpendicular to the first conductive channel direction s. The length of the first conductive channel 226 in the first conductive channel direction s changes less with the tensile strain borne by the first conductive channel 226, and the carrier mobility in the first conductive channel 226 changes less with the tensile strain borne by the first conductive channel 226. Therefore, the turn-on current of the first thin film transistor 22 changes less with the tensile strain borne by the first conductive channel 226, the driving current of the bent display area 20 is less different from that of the non-bending display area, and the display brightness difference between the bent display area 20 and the non-bending display area is smaller.

[0062] It can be understood that when the angle between the first conductive channel direction s and the bending axis 21 is 65 degrees to 75 degrees, the angle between the first conductive channel direction s and the tensile strain on the first conductive channel 226 is 15 degrees to 25 degrees. When the angle between the first conductive channel direction s and the bending axis 21 is 90 degrees, the angle between the first conductive channel direction s and the tensile strain on the first conductive channel 226 is 0 degrees. When the angle between the first conductive channel direction s and the bending axis 21 is 45 degrees, the angle between the first conductive channel direction s and the tensile strain on the first conductive channel 226 is 45 degrees. When the angle between the first conductive channel direction s and the bending axis 21 is 0 degrees, the angle between the first conductive channel direction s and the tensile strain on the first conductive channel 226 is 90 degrees.

[0063] See also Figure 7 , Figure 7 A curve diagram showing the change of carrier mobility in the first thin film transistor 22 with the tensile strain provided in an embodiment of the present application, specifically, a curve diagram showing the change of carrier mobility in the first thin film transistor 22 with the tensile strain when the first thin film transistor 22 is subjected to tensile strain and the angle between the tensile strain direction and the first conductive channel direction s is 0 degrees, 15 degrees to 25 degrees, 45 degrees and 90 degrees respectively. Figure 7 It can be seen that when the angle between the first conductive channel direction s and the tensile strain to which the first conductive channel 226 is subjected is 0 degrees, the carrier mobility in the first conductive channel 226 decreases as the tensile strain to which the first conductive channel 226 is subjected increases. When the angle between the first conductive channel direction s and the tensile strain to which the first conductive channel 226 is subjected is 45 degrees, the carrier mobility in the first conductive channel 226 increases as the tensile strain to which the first conductive channel 226 is subjected increases. When the angle between the first conductive channel direction s and the tensile strain to which the first conductive channel 226 is subjected is 90 degrees, the carrier mobility in the first conductive channel 226 increases as the tensile strain to which the first conductive channel 226 is subjected increases. When the angle between the first conductive channel direction s and the tensile strain on the first conductive channel 226 is 15 to 25 degrees, the carrier mobility in the first conductive channel 226 remains substantially unchanged as the tensile strain on the first conductive channel 226 changes.

[0064] In one embodiment, a plurality of second thin film transistors are further provided on the bent display area, each second thin film transistor includes a second source and a second drain, a second conductive channel is formed between the second source and the second drain of each second thin film transistor, and the direction of the second conductive channel is consistent with the direction s of the first conductive channel, wherein the total length of each part of the second conductive channel in the direction of the second conductive channel is greater than the total length of each part of the second conductive channel in any other direction.

[0065] A first thin film transistor 22 can form a 2T1C structure TFT driving circuit with two second thin film transistors and a capacitor, a first thin film transistor 22 can also form a 6T1C structure TFT driving circuit with six second thin film transistors and a capacitor, a first thin film transistor 22 can also form a 7T1C structure TFT driving circuit with seven second thin film transistors and a capacitor, or a first thin film transistor 22 can also form a 5T2C structure TFT driving circuit with five second thin film transistors and two capacitors, and so on, and a TFT driving circuit is used to drive a sub-pixel to emit light. The second thin film transistor of the above-mentioned TFT driving circuit is used as a switch thin film transistor to control whether the current enters the driving circuit, and the first thin film transistor 22 is used as a driving thin film transistor, which is connected to the power supply voltage and provides a driving current for the sub-pixel within a certain period of time.

[0066] By setting the direction of the second conductive channel of the second thin film transistor in the bent display area to be the same as the direction s of the first conductive channel, the manufacturing process of the thin film transistor of the display panel can be simplified and the cost can be saved.

[0067] In other embodiments, the second conductive channel direction may also be different from the first conductive channel direction s.

[0068] Please refer to Figure 1 In one embodiment, a plurality of third thin film transistors 42 are disposed on the non-bending display area 40. Each third thin film transistor 42 includes a third source and a third drain, and a third conductive channel is formed between the third source and the third drain of each third thin film transistor 42. The direction of the third conductive channel is inconsistent with the direction s of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction. The third thin film transistor 42 includes a switch thin film transistor and a drive thin film transistor.

[0069] In one embodiment, a plurality of third thin film transistors 42 are disposed on the non-bending display area 40. Each third thin film transistor 42 includes a third source and a third drain, and a third conductive channel is formed between the third source and the third drain of each third thin film transistor 42. The direction of the third conductive channel is consistent with the direction s of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction. The third thin film transistor 42 includes a switch thin film transistor and a drive thin film transistor.

[0070] In this embodiment, by setting the third conductive channel direction of the third thin film transistor 42 of the non-bending display area 40 to be the same as the first conductive channel direction s, the manufacturing process of the thin film transistor of the display panel can be simplified and the cost can be saved.

[0071] The first thin film transistor 22, the second thin film transistor, and the third thin film transistor 42 are all polysilicon thin film transistors. Further, the first thin film transistor 22, the second thin film transistor, and the third thin film transistor 42 are all low-temperature polysilicon thin film transistors. The use of low-temperature polysilicon thin film transistors can make the flexible screen including the above display panel have the advantages of high mobility, fast response speed, high resolution, high brightness, high aperture ratio, etc.

[0072] The embodiment of the present application also provides an electronic device, the electronic device includes a display screen, and the display screen includes the display panel described in any of the above embodiments. The electronic device can be an e-book, a television, a computer, a handheld computer, a car display, a tablet computer, a smart phone, a wearable device, etc.

[0073] Please refer to Figure 8 The present application also provides a method for manufacturing a display panel, specifically a method for manufacturing a first thin film transistor in a bent display area, comprising the following steps:

[0074] Step S10, providing a substrate 50, wherein the substrate comprises a bending display area, and the bending display area has a bending axis. The substrate 50 can be a polymer plastic substrate or other suitable materials.

[0075] Please also refer to Fig. 9 , step S20 , forming a buffer layer 51 on the substrate 50 .

[0076] Specifically, the buffer layer 51 can be deposited by physical vapor deposition, chemical vapor deposition or plasma assisted chemical vapor deposition. The material of the buffer layer 51 can be silicon oxide (SiOX), silicon nitride (SiNx) or a combination of the two. The buffer layer 51 can be a one-layer or multi-layer structure. When the buffer layer 51 is a one-layer structure, its material can be, for example, silicon oxide (SiOX) or silicon nitride (SiNx). When the buffer layer 51 is a two-layer or more structure, it can be a composite film layer of a silicon oxide layer and a silicon nitride layer.

[0077] Step S30 , depositing an amorphous silicon film on the buffer layer 51 , performing polycrystallization on the amorphous silicon film to form a polycrystalline silicon film, and performing patterning on the polycrystalline silicon film to form an active layer 52 on the buffer layer 51 .

[0078] For example, the amorphous silicon film is deposited on the buffer layer 51 by plasma enhanced chemical vapor deposition (PECVD) to deposit a layer of amorphous silicon film on the buffer layer 51, and a high-temperature oven is used to perform a dehydrogenation process on the amorphous silicon film to prevent hydrogen explosion during the crystallization process and reduce the defect state density inside the film after crystallization. After the dehydrogenation process is completed, a low-temperature polysilicon process is performed, and a crystallization method such as laser annealing (ELA), metal induced crystallization (MIC), and solid phase crystallization (SPC) is used to crystallize the amorphous silicon film to form an active layer 52 on the buffer layer 51.

[0079] Alternatively, an amorphous silicon film may be deposited on the substrate formed with the buffer layer 51, and a patterning process may be performed to form a reserved pattern in a predetermined area, and then the reserved pattern may be polycrystallized to form a channel region pattern. The patterning process includes steps such as masking, exposure, development, etching, and photoresist stripping.

[0080] Step S40 , forming a gate insulating layer 53 on the patterned active layer 52 .

[0081] The material of the gate insulating layer 53 may include at least one of silicon oxide and silicon nitride.

[0082] Step S50 , forming a first metal layer on the gate insulating layer 53 , and patterning the first metal layer to form a gate 54 located above the active layer 52 .

[0083] In the process of forming the gate 54, ions are implanted into the active layer 52, so that the active layer 52 includes a first conductive channel, a first source region and a first drain region, and the first conductive channel is formed between the first source region and the first drain region. The angle between the first conductive channel direction and the bending axis is less than 90 degrees. The total length of each part of the first conductive channel in the direction of the first conductive channel is greater than the total length of each part of the first conductive channel in any other direction.

[0084] When the first source region and the first drain region do not distinguish between lightly doped regions and heavily doped regions, after forming the gate 54, ion implantation can be performed on the active layer 52 with the gate 54 as a barrier, so that the active layer 52 includes a first conductive channel, a first source region and a first drain region located on both sides of the first conductive channel.

[0085] When the first source region and the first drain region include a lightly doped region and a heavily doped region, a half-tone mask can be used to expose the photoresist when forming the gate 54, and the completely reserved portion of the photoresist covers the region corresponding to the gate 54, the half-reserved portion of the photoresist covers the region corresponding to the lightly doped region to be formed in the polysilicon film, and the unreserved portion of the photoresist covers the region corresponding to the heavily doped region to be formed in the polysilicon film. In this way, after the photoresist is developed, ion implantation can be performed on the exposed polysilicon film to form a heavily doped region; then an ashing process is performed to remove the half-reserved portion of the photoresist, and the exposed first metal layer is etched to form the gate 54, and then the gate 54 is used as a barrier to implant ions into the exposed active layer 52, so that the active layer 52 forms a lightly doped region except for the heavily doped region and the first conductive channel corresponding to the gate 54.

[0086] The material of the gate 54 may be, for example, molybdenum (Mo), aluminum (Al) / molybdenum, copper (Cu), etc.

[0087] Step S60 , forming a gate dielectric layer 56 on the patterned first metal layer.

[0088] The material of the gate dielectric layer 56 may be, for example, silicon nitride.

[0089] Step S70 , forming an interlayer insulating layer 58 on the gate dielectric layer 56 .

[0090] The material of the interlayer insulating layer 58 may be, for example, silicon nitride.

[0091] Step S80 , forming a first via hole 61 and a second via hole 62 , wherein the first via hole 61 and the second via hole 62 expose the first source region and the first drain region respectively.

[0092] The first via hole 61 and the second via hole 62 may be formed simultaneously or separately by a wet etching process or a plasma dry etching process.

[0093] In step S90 , a patterned source-drain metal layer 64 is formed, and the first source and the first drain are overlapped. The source-drain metal layer 64 includes the first source and the first drain.

[0094] The material of the source-drain metal layer 64 may be, for example, Mo, Al / Mo, Cu, etc.

[0095] The above-mentioned method for manufacturing the display panel is also applicable to the manufacturing of the second thin film transistor in the bent display area and the third thin film transistor on the non-bent display area of ​​the display panel, and each step of the manufacturing process of the second thin film transistor in the bent display area and the third thin film transistor on the non-bent display area can be carried out simultaneously with the corresponding manufacturing process of the first thin film transistor on the bent area, which will not be elaborated here.

[0096] After the TFT of the display panel is manufactured, the manufacturing method of the display panel may further include:

[0097] A passivation layer and a planarization layer are formed in sequence; an indium tin oxide semiconductor transparent conductive layer is formed; a pixel definition layer is formed and a pattern definition is performed; and a display panel is formed by evaporation packaging.

[0098] The manufacturing method of the display panel of the embodiment of the present application, when manufacturing the first thin film transistor of the bent display area of ​​the display panel, by setting the direction of the first conductive channel of the first thin film transistor in the bent display area to an angle less than 90 degrees with the bending axis, so that the angle between the direction of the first conductive channel and the strain direction of the first conductive channel is not 0 degrees, the strain along the direction of the first conductive channel of the first conductive channel is reduced compared to when the direction of the first conductive channel is parallel to the strain direction of the first conductive channel, the carrier mobility in the first conductive channel changes less, the turn-on current of the first thin film transistor changes less, the driving current of the bent display area changes less, the display brightness difference between the bent display area and the non-bent display area is reduced, and the display effect of the display panel is improved.

[0099] In one of the embodiments, when the bending of the substrate causes the first conductive channel to be subjected to compressive strain, the angle between the direction of the first conductive channel and the bending axis is 0 to 5 degrees. Preferably, when the angle between the direction of the first conductive channel and the bending axis is 0 degrees, the compressive strain on the first conductive channel is perpendicular to the direction of the first conductive channel, the length of the first conductive channel in the direction of the first conductive channel does not change with the change of the compressive strain on the first conductive channel, the carrier mobility in the first conductive channel does not change with the change of the compressive strain on the first conductive channel, and thus the turn-on current of the first thin film transistor does not change with the change of the compressive strain on the first conductive channel, the driving current of the bent display area is the same as the driving current of the non-bent display area, and the display brightness of the bent display area is consistent with that of the non-bent display area.

[0100] In one of the embodiments, when the bending of the substrate causes the first conductive channel to be subjected to tensile strain, the angle between the direction of the first conductive channel and the bending axis is 65 to 75 degrees. When the bending of the substrate causes the first conductive channel to be subjected to tensile strain, the angle between the direction of the first conductive channel and the bending axis is set to 65 to 75 degrees, the tensile strain to which the first conductive channel is subjected is mostly perpendicular to the direction of the first conductive channel, the length of the first conductive channel in the direction of the first conductive channel changes less with the tensile strain to which the first conductive channel is subjected, the carrier mobility in the first conductive channel changes less with the tensile strain to which the first conductive channel is subjected, and thus the turn-on current of the first thin film transistor changes less with the tensile strain to which the first conductive channel is subjected, the driving current of the bent display area is less different from the driving current of the non-bent display area, and the display brightness difference between the bent display area and the non-bent display area is less.

[0101] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A display panel, characterized in that: The device comprises a bending display area, the bending display area has a bending axis, a plurality of first thin film transistors are arranged on the bending display area, each of the first thin film transistors comprises a first source electrode and a first drain electrode, a first conductive channel is formed between the first source electrode and the first drain electrode of each of the first thin film transistors, and an angle formed between the direction of the first conductive channel and the bending axis is less than 90 degrees; wherein the total length of each part of the first conductive channel in the direction of the first conductive channel is greater than the total length of each part of the first conductive channel in any other direction; When the display panel is bent so that the first thin film transistor is subjected to tensile strain, an angle formed between a first conductive channel direction of the first thin film transistor and the bending axis is 65 degrees to 75 degrees.

2. The display panel according to claim 1, wherein: When the display panel is bent so that the first thin film transistor is subjected to compressive strain, an angle formed between a first conductive channel direction of the first thin film transistor and the bending axis is 0 degrees to 5 degrees.

3. The display panel according to claim 2, wherein: The angle formed between the first conductive channel direction of the first thin film transistor and the bending axis is 0 degree.

4. The display panel according to claim 1, wherein: A plurality of second thin film transistors are also arranged on the bent display area, each of the second thin film transistors includes a second source and a second drain, a second conductive channel is formed between the second source and the second drain of each second thin film transistor, and the direction of the second conductive channel is consistent with the direction of the first conductive channel, wherein the total length of each part of the second conductive channel in the direction of the second conductive channel is greater than the total length of each part of the second conductive channel in any other direction.

5. The display panel according to claim 4, wherein: The first thin film transistor and the second thin film transistor are both low temperature polysilicon thin film transistors.

6. The display panel according to claim 1, wherein: It also includes a non-bending display area, on which a plurality of third thin film transistors are arranged, each of the third thin film transistors includes a third source and a third drain, a third conductive channel is formed between the third source and the third drain of each of the third thin film transistors, and the direction of the third conductive channel is inconsistent with the direction of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction.

7. The display panel according to claim 1, wherein: It also includes a non-bending display area, on which a plurality of third thin film transistors are arranged, each of the third thin film transistors includes a third source and a third drain, a third conductive channel is formed between the third source and the third drain of each of the third thin film transistors, and the direction of the third conductive channel is consistent with the direction of the first conductive channel, wherein the total length of each part of the third conductive channel in the direction of the third conductive channel is greater than the total length of each part of the third conductive channel in any other direction.

8. The display panel according to claim 6 or 7, characterized in that: The third thin film transistor is a low temperature polysilicon thin film transistor.

9. An electronic device, characterized in that: Comprising a display panel as described in any one of claims 1-8.

10. A method for manufacturing a display panel, characterized in that: include: Providing a substrate, wherein the substrate comprises a bending display area, and the bending display area has a bending axis; forming a buffer layer on the substrate; Depositing an amorphous silicon film on the buffer layer, performing polycrystallization on the amorphous silicon film to form a polycrystalline silicon film, and performing patterning on the polycrystalline silicon film to form an active layer located on the buffer layer; forming a gate insulating layer on the patterned active layer; forming a first metal layer on the gate insulating layer, and patterning the first metal layer to form a gate located above the active layer; Wherein, in the process of forming the gate, ion implantation is performed on the active layer so that the active layer includes a first conductive channel, a first source region and a first drain region, the first conductive channel is formed between the first source region and the first drain region, the angle between the first conductive channel direction and the bending axis is less than 90 degrees, and the total length of each part of the first conductive channel in the direction of the first conductive channel is greater than the total length of each part of the first conductive channel in any other direction; When the bending of the substrate causes the first conductive channel to be subjected to tensile strain, an angle between the direction of the first conductive channel and the bending axis is 65 degrees to 75 degrees.

11. The method for manufacturing a display panel according to claim 10, wherein: Also includes: forming a gate dielectric layer on the patterned first metal layer; forming an interlayer insulating layer on the gate dielectric layer; forming a first via hole and a second via hole, wherein the first via hole and the second via hole respectively expose the first source region and the first drain region; A patterned source-drain metal layer is formed, and the first source and the first drain are overlapped, wherein the source-drain metal layer includes the first source and the first drain.

12. The method for manufacturing a display panel according to claim 10, wherein: When the bending of the substrate causes the first conductive channel to be subjected to compressive strain, an angle between the direction of the first conductive channel and the bending axis is 0 degrees to 5 degrees.

13. The method for manufacturing a display panel according to claim 12, wherein: The angle between the first conductive channel direction and the bending axis is 0 degree.

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