Electrowetting display panel, display device and preparation method thereof

Abstract

The invention discloses a novel electrowetting display panel and a display device thereof. The display panel comprises a substrate, a supporting structure arranged on the substrate and a pixel electrode formed on the supporting structure. The supporting structure is provided with a slope surface, so that the working surface of the pixel electrode covering the supporting structure presents a corresponding inclined or arched geometrical morphology, and the inclination angle of the slope surface is preferably 10-30 degrees. The support structure can be formed by photoresist through halftone mask exposure, development and hot reflux processes. The preparation method comprises the steps of forming the supporting structure with the slope surface, and sequentially forming the pixel electrode and the hydrophobic insulating layer on the supporting structure. Effective directional guiding force is provided for ink shrinkage through the slope electrode structure, and rapid and complete resetting of ink can be realized under low driving voltage, so that the response speed and the contrast ratio of the display panel are remarkably improved, the power consumption is reduced, and the key problem that the electrowetting display performance of a traditional planar electrode is limited is solved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically, to a novel electrowetting display panel and display device thereof. Background Technology

[0002] Electrowetting display technology, due to its low power consumption, high reflectivity, and paper-like texture, has become one of the ideal display solutions for e-readers, wearable devices, and other fields. Its basic principle is to apply an electric field to change the wettability of the surface of the hydrophobic insulating layer, thereby driving the coloring ink to shrink or spread, and realizing the switching between the bright and dark states of the pixels.

[0003] However, traditional electrowetting display panels generally employ a planar electrode design. In this structure, when the driving voltage is removed, the ink mainly relies on its own surface tension and the recovery of the interfacial energy difference with the hydrophobic layer to shrink towards the pixel edge. This shrinkage process lacks sufficient driving force and has a relatively long path, resulting in incomplete ink shrinkage and slow speed, which in turn causes problems such as decreased display contrast, image retention (trailing), and difficulty in improving response speed. To improve performance, existing technologies mostly focus on optimizing the driving waveform, increasing the driving voltage, or improving the ink formulation, but these methods often have limitations in terms of energy consumption, material cost, or performance improvement. For example, increasing the driving voltage will significantly increase power consumption and may affect device reliability; while the optimization of ink formulation is limited by the physicochemical properties of materials, and there is a ceiling to the improvement of response speed.

[0004] Chinese invention patent CN111522138B discloses a structure with an independent ink storage tank, aiming to improve ink movement and solve the trailing problem through physical structural separation. This solution increases structural complexity and process steps, and does not fundamentally change the influence of electrode surface geometry on the ink shrinkage driving force.

[0005] Therefore, there is an urgent need to develop a new type of electrowetting display panel that can provide an effective directional driving force for the ink shrinkage process after power failure, thereby achieving rapid and thorough ink reset while ensuring low power consumption, in order to solve the key technical problem of current electrowetting display panels in terms of performance improvement. Summary of the Invention

[0006] Therefore, it is necessary to provide an electrowetting display panel, a display device, and a method for manufacturing the above-mentioned technical problems.

[0007] To address the aforementioned technical problems, a first aspect of the present invention provides an electrowetting display panel, comprising: lower base plate; A support structure disposed on the lower substrate has a sloping surface. Pixel electrodes formed on the sloping surface of the support structure.

[0008] Furthermore, it also includes a hydrophobic insulating layer disposed on the pixel electrode.

[0009] Furthermore, the sloping surface of the supporting structure is arched.

[0010] Furthermore, the slope surface of the support structure is inclined in a single direction.

[0011] Furthermore, the inclination angle of the slope surface of the support structure is 10°~30°.

[0012] Furthermore, the material of the support structure includes photoresist, and the slope surface is formed by exposure, development and thermal reflow of the photoresist through a halftone mask.

[0013] Furthermore, the pixel electrode is an indium tin oxide thin film with a thickness of 10 nm to 150 nm.

[0014] Furthermore, the support structure is formed by photoresist through thermal reflow, and the thickness of the support structure is 0.1~5μm.

[0015] A second aspect of this invention provides a method for preparing an electrowetting display panel, comprising the following steps: Photoresist is coated onto the lower substrate; The photoresist is exposed and developed using a halftone mask to form a stepped pattern; The developed photoresist is subjected to thermal reflow treatment to form a support structure with a sloping surface; Pixel electrodes are formed on the sloping surface of the support structure. A hydrophobic insulating layer is formed on the pixel electrode.

[0016] A third aspect of the present invention provides a display device comprising an electrowetting display panel as described in any of the preceding claims, which is particularly suitable for applications such as e-readers, wearable devices, and electronic price tags that have high requirements for power consumption and display performance.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a novel electrowetting display panel and its display device. By constructing a ramp or arch support structure with a specific tilt angle, the working surface of the pixel electrode presents a directional tilt morphology. Utilizing the directional guiding force such as the gravitational component and capillary action generated after pressure release, the ink shrinkage speed and thoroughness are improved, achieving millisecond-level fast response and effectively avoiding image trailing. By coordinating the electric field force and the pre-set tendency force of the ramp, the ink spreading and resetting efficiency are improved, thereby avoiding the need for high driving voltage and significantly reducing power consumption. By ensuring that the ink completely shrinks to the edge area, the brightness and darkness contrast of the pixels are improved. By adopting mature photoresist halftone masks and thermal reflow processes, the process compatibility with existing production lines is improved, avoiding complex processes and high costs. By flexibly designing symmetrical / asymmetrical arches or unidirectional ramps and their angles, the adaptability of the structure to different display performance requirements is improved. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the electrowetting display panel with symmetrical arched slope electrodes provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the state of ink spreading (pixel activation) of the electrowetting display panel of Example 1 after a driving voltage is applied; Figure 3 This is a schematic diagram of the state of ink shrinkage (pixel shutdown) of the electrowetting display panel of Example 1 after the driving voltage is removed; Figures 4 to 7 This is a cross-sectional schematic diagram of the fabrication process steps of the arched slope electrode structure in the electrowetting display panel of Embodiment 1 of the present invention; wherein: Figure 4 This is a schematic diagram of coating photoresist on a substrate; Figure 5 This is a schematic diagram illustrating the step-like pattern formed after exposure and development using a halftone mask. Figure 6 This is a schematic diagram of a smooth arched ramp support structure formed after hot reflow treatment of a stepped pattern. Figure 7 A schematic diagram showing the formation of pixel electrodes and hydrophobic insulating layers on an arched sloping support structure; Figure 8 This is a schematic diagram of the structure of the electrowetting display panel with asymmetric arched slope electrodes provided in Embodiment 2 of the present invention; Figure 9 This is a schematic diagram of the structure of the electrowetting display panel with a unidirectional ramp electrode provided in Embodiment 3 of the present invention; Figure 10 This is a schematic diagram of the state of ink spreading (pixel activation) of the electrowetting display panel in Example 3 after a driving voltage is applied; Figure 11This is a schematic diagram of the state of ink shrinkage (pixel shutdown) of the electrowetting display panel in Example 3 after the driving voltage is removed; Figure 12 A schematic diagram of the ink spreading (pixel activation) state of a conventional planar electrode electrowetting display panel provided for Comparative Example 1 after the application of a driving voltage; Figure 13 This is a schematic diagram of a conventional planar electrode electrowetting display panel provided for Comparative Example 1, showing incomplete ink shrinkage (pixel shutdown) after the driving voltage is removed.

[0019] The markings in the diagram are explained as follows: Lower base plate 10; First electrode structure 20, first pixel electrode 21, first hydrophobic insulating layer 22; Ink 30; Pixel wall 40; upper base plate 50; Second electrode structure 60, second pixel electrode 61, second hydrophobic insulating layer 62; Third electrode structure 70. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] Example 1 This embodiment provides an electrowetting display panel, which includes a lower substrate 10, a first electrode structure 20 disposed on the lower substrate 10, a pixel wall 40 disposed around the first electrode structure 20, and ink 30 located in a cavity surrounded by the pixel wall 40 and an upper substrate 50. The first electrode structure 20 includes a first pixel electrode 21 and a first hydrophobic insulating layer 22 covering the first pixel electrode 21. The first pixel electrode 21 is formed on an arched slope support structure symmetrical about the pixel center, such that at least a portion of the working surface of the electrode exhibits a corresponding arched slope morphology. The arched slope support structure is composed of two symmetrical inclined planes, with the angles between the left and right inclined planes and the plane of the lower substrate 10 being inclination angles θ1 and θ2, respectively. In this embodiment, both θ1 and θ2 are 15°.

[0022] The method for preparing the electrowetting display panel includes the following steps: S1. Substrate preparation: Provide a clean glass under-substrate 10.

[0023] S2. Forming a symmetrical arched support structure: A layer of positive photoresist (AZ®1500 in this embodiment) is spin-coated onto the lower substrate 10, with a wet film thickness controlled at 3.0 μm. Pre-baking is then performed to remove the solvent. A specially designed halftone mask (HTM) is used for ultraviolet (i-line) exposure. Within a single pixel area, the transmittance distribution of this mask is designed such that, along the pixel width direction, the transmittance is lowest in the center line region (approximately 10%), linearly increasing to 100% towards the left and right pixel edges. After exposure, development is performed to form a stepped relief pattern with a higher center and lower sides.

[0024] S3. Hot Reflow Molding: The developed substrate is placed in an oven at 155°C for hot reflow treatment for 6 minutes. The photoresist flows under heat, eventually forming a smooth and continuous arched ramp support structure symmetrical about the pixel centerline. Measurements using a profilometer show that the inclination angles θ1 and θ2 of the ramps on both sides of the arched support structure are both 15°.

[0025] S4. Forming the arched slope pixel electrode: An indium tin oxide (ITO) thin film with a thickness of 70 nm is deposited on the arched slope structure using a magnetron sputtering process. Subsequently, the ITO thin film is patterned using standard photolithography and wet etching processes to form the first pixel electrode 21 that is completely aligned with the arched morphology below.

[0026] S5. Forming a hydrophobic insulating layer: A polytetrafluoroethylene (PTFE) solution is coated onto the surface of the first pixel electrode 21 by spin coating and cured to form a first hydrophobic insulating layer 22 with a thickness of approximately 1.0 μm. This constitutes the first electrode structure 20 with a symmetrical arched working surface.

[0027] S6. Formation of pixel walls and subsequent assembly: Pixel walls 40 for separating pixels are formed on the first electrode structure 20 using a photolithography process. Subsequently, they are assembled and sealed with the upper substrate 50 with a common electrode, and then an aqueous solution and ink 30 are injected to complete the fabrication of the display panel.

[0028] When a voltage is applied between the first pixel electrode 21 and the common electrode, the ink 30 contracts, and the pixel opens. When the voltage is removed, the symmetrical arched ramp structure simultaneously generates a directional guiding force pointing towards the pixel edge on both sides. This guiding force originates from the surface tension gradient generated by the ramp structure and works in conjunction with the component of gravity to form a capillary force that drives the directional movement of the ink. This effectively overcomes the viscous resistance of the ink, driving the ink 30 to contract rapidly and completely from the pixel center to the two side edges, significantly shortening the phase change path and contraction time of the ink.

[0029] Example 2 This embodiment provides an electrowetting display panel, the structure of which differs from that of Embodiment 1 in that: the first pixel electrode 21 is formed on an asymmetrical arched slope support structure with respect to the pixel center, such that at least a portion of the working surface of the electrode exhibits a corresponding asymmetrical arched slope morphology. The apex of the arched slope is biased towards one side of the pixel and is composed of two planes with different inclination angles, wherein the slope inclination angle θ1 towards one edge of the pixel is 10°, and the slope inclination angle θ2 towards the other edge is 25°.

[0030] S1. Substrate preparation: Same as in Example 1.

[0031] S2. Forming an asymmetric arched support structure: A layer of positive photoresist is spin-coated onto the lower substrate 10, with a wet film thickness controlled at 1.5 μm. A specially designed halftone mask (HTM) is used for exposure. The transmittance distribution of this mask is reverse-designed based on the asymmetric morphology of the target support structure (one side tilt angle is approximately 10°, and the other side tilt angle is approximately 25°). Its distribution within the pixel area is non-linear and asymmetric, resulting in an asymmetric stepped pattern with corresponding height differences on the photoresist layer after exposure and development. The substrate is then subjected to a thermal reflow treatment at 150°C for 7 minutes. The photoresist flows under heat, forming a smooth, asymmetric arched ramp support structure. Measurements show that the ramp angles θ1 are 10° and θ2 are 25°.

[0032] S3. Forming an asymmetric arched slope pixel electrode: An ITO thin film with a thickness of 50 nm is deposited on the above-mentioned support structure using a magnetron sputtering process. Subsequently, it is patterned using photolithography and etching processes to form the first pixel electrode 21.

[0033] S4. Forming a hydrophobic insulating layer: The steps are the same as in Example 1, forming a first hydrophobic insulating layer 22.

[0034] S5. Forming pixel walls and subsequent assembly: The steps are the same as in Example 1.

[0035] When the voltage is removed, the asymmetric arched ramp structure generates directional guiding forces pointing towards their respective edges on both sides simultaneously. Due to the different inclination angles of the two ramps, the resulting surface tension gradient and gravitational component differ, leading to different magnitudes of capillary forces driving ink contraction. The capillary driving force generated on the steeper side (θ2 = 25°) is significantly stronger, while the gentler side (θ1 = 10°) also provides guiding forces within the optimization range of this invention. Under the combined action of these asymmetric driving forces, the ink primarily contracts and gathers rapidly and completely towards the 25° side, while also coordinating its movement along the 10° side, thus achieving rapid and complete removal of the ink from the pixel display area.

[0036] Example 3 This embodiment provides an electrowetting display panel, which includes a lower substrate 10, a second electrode structure 60 disposed on the lower substrate 10, a pixel wall 40 disposed around the second electrode structure 60, and ink 30 located within a cavity. The second electrode structure 60 includes a second pixel electrode 61 and a second hydrophobic insulating layer 62 completely covering the second pixel electrode 61. The second pixel electrode 61 is formed on a slope support structure inclined in a single direction, such that at least a portion of the working surface of the electrode exhibits a corresponding unidirectional inclined slope morphology. Its tilt angle θ is 20°.

[0037] The method for preparing the electrowetting display panel includes the following steps: S1. Substrate preparation: Same as in Example 1.

[0038] S2. Forming a 20° unidirectional ramp support structure: A layer of positive photoresist is spin-coated onto the lower substrate 10, with the wet film thickness controlled at 5.0 μm. An HTM mask with a linearly gradient transmittance from one pixel side (0%) to the other (100%) is used for UV exposure and development. Subsequently, a thermal reflow treatment is performed at 148°C for 6.5 minutes to form a smooth unidirectional ramp support structure. The tilt angle θ of this support structure is measured to be 20° using a profilometer.

[0039] S3. Forming a 20° unidirectional slope pixel electrode: A 100nm thick ITO film is deposited on the aforementioned unidirectional slope support structure using magnetron sputtering. The film is then patterned using standard photolithography and etching processes to form the second pixel electrode 61.

[0040] S4. Forming a hydrophobic insulating layer covering the electrode: On the surface of the second pixel electrode 61, a PTFE solution is coated by spin coating and cured to form a second hydrophobic insulating layer 62.

[0041] S5. Forming pixel walls and completing device assembly: Pixel walls 40 are formed on the second electrode structure 60 using photolithography. Subsequently, they are assembled and sealed with the upper substrate 50 containing the common electrode, and then an aqueous solution and ink 30 are injected to complete the fabrication of the display panel.

[0042] When the voltage is removed, the 20° unidirectional ramp structure generates a directional guiding force pointing towards the low edge of the pixel, driving the ink 30 to shrink rapidly and completely towards that side.

[0043] Example 4 This embodiment provides an electrowetting display panel, which has a structure similar to that of embodiment 3, except that the slope tilt angle θ of the working surface of the second pixel electrode 61 in the second electrode structure 60 is 10°.

[0044] Its preparation method is as follows: S1: Same as Example 1.

[0045] S2: Form a 10° unidirectional sloping support structure. The process is the same as in Example 3, except that the transmittance gradient of the HTM mask and the reflow conditions are adjusted to 152°C for 7.5 minutes, so that the final support structure tilt angle θ is 10°. The wet film thickness is 2.2μm.

[0046] S3: Form a 10° unidirectional slope pixel electrode. Deposit an ITO film with a thickness of 150 nm.

[0047] S4~S5: Same as Example 3.

[0048] When the voltage is removed, the directional guiding force generated by the 10° unidirectional ramp structure, pointing towards the low edge of the pixel, can provide effective driving while maintaining low ink flow resistance, thereby achieving rapid and complete ink shrinkage at a lower driving voltage. This demonstrates the advantage of a smaller tilt angle in balancing low driving voltage and effective reset.

[0049] Example 5: Display panel with 30° unidirectional ramp electrode This embodiment provides an electrowetting display panel, which has a structure similar to that of embodiment 3, except that the slope tilt angle θ of the working surface of the second pixel electrode 61 in the second electrode structure 60 is 30°.

[0050] Its preparation method is as follows: S1: Same as Example 1.

[0051] S2: Form a 30° unidirectional sloping support structure. The process is the same as in Example 3, except that the transmittance gradient of the HTM mask and the reflow conditions are adjusted to 160°C for 5.5 minutes, so that the final support structure tilt angle θ is 30° and the wet film thickness is 4.0μm.

[0052] S3: Form a 30° unidirectional slope pixel electrode. Deposit an ITO film with a thickness of 40 nm.

[0053] S4~S5: Same as Example 3.

[0054] When the voltage is removed, the directional guiding force generated by the 30° unidirectional ramp structure pointing towards the low edge of the pixel becomes more significant. It can overcome ink stickiness with a stronger driving force, thereby achieving complete and high-speed ink reset in application scenarios that require faster response. This demonstrates the value of a larger tilt angle in pursuing extreme response speed.

[0055] Comparative Example 1: Traditional planar electrode structure This comparative example provides an electrowetting display panel, which includes a lower substrate 10, a third electrode structure 70 disposed on the lower substrate 10, a pixel wall 40, and ink 30. The third electrode structure 70 includes a planar pixel electrode and a hydrophobic insulating layer covering it; the working surface of the pixel electrode is planar and has no tilt angle.

[0056] Its preparation method is as follows: S1: Provides the lower substrate 10.

[0057] S2: A 70nm thick planar ITO pixel electrode is directly deposited and patterned on the lower substrate 10.

[0058] S3: A hydrophobic insulating layer is formed on the planar pixel electrode, thereby completing the fabrication of the third electrode structure 70.

[0059] S4~S5: Same as in Example 1, form pixel wall 40 and complete assembly.

[0060] When the voltage is removed from the comparative sample, the planar electrode structure cannot provide directional guiding force. The ink shrinkage depends entirely on the natural recovery of the interfacial tension difference. The path is long and the driving force is weak, resulting in slow and incomplete ink shrinkage. This leads to a slow response speed and low contrast in the off state of the display panel, and requires a higher driving voltage to compensate.

[0061] Comparative Example 2 This comparative example provides an electrowetting display panel, which has a structure similar to that of Embodiment 3, except that the slope tilt angle θ of the working surface of the second pixel electrode 61 in the second electrode structure 60 is only about 5°.

[0062] Its preparation method is as follows: S1~S2: The process is the same as in Example 3, but the parameters are adjusted so that the slope angle of the final support structure is θ≈5°. The wet film thickness is 0.5μm, and the heat reflow conditions are 140℃ for 9 minutes.

[0063] S3~S5: Same as Example 3. The ITO film thickness is 120nm.

[0064] When the voltage was removed, the relatively small tilt angle of about 5° in this comparative sample resulted in extremely weak directional guiding force generated by the ramp structure, which was insufficient to effectively overcome the viscous resistance of the ink. Therefore, the improvement in ink shrinkage speed and integrity was limited, and the fast response and high contrast effect expected by this invention could not be achieved, proving the shortcomings of the excessively small tilt angle.

[0065] Comparative Example 3 This comparative example provides an electrowetting display panel, the structure of which is similar to that of Embodiment 3, except that the slope tilt angle θ of the working surface of the second pixel electrode 61 in the second electrode structure 60 is 40°.

[0066] Its preparation method is as follows: S1~S2: The process is the same as in Example 3, but the parameters are adjusted so that the slope angle θ of the final support structure is 40°. The wet film thickness is 5.0 μm, and the heat reflow conditions are 165°C for 5 minutes.

[0067] S3~S5: Same as Example 3. The ITO film thickness is 20nm.

[0068] When the voltage is removed, the excessive tilt angle of 40° in this comparative sample can generate a large component of gravity, but it also increases the flow resistance and instability due to the change in the ink spreading state and the steep flow path. This makes the ink shrinkage process prone to rebound or unevenness, which is not conducive to achieving stable and rapid complete reset.

[0069] Comparative Example 4 This comparative example provides an electrowetting display panel whose structure differs from that of Example 3 only in that the step of forming the second hydrophobic insulating layer 62 is omitted.

[0070] Its preparation method is as follows: S1~S3: Process parameters are the same as in Example 3.

[0071] S4, Omit the hydrophobic insulating layer: Do not coat any hydrophobic insulating material.

[0072] S5: Same as Example 3.

[0073] In this comparative sample, the lack of a hydrophobic insulating layer significantly increased the adhesion between the ink and the electrode surface. Even with a 20° unidirectional slope structure, some of the directional guiding force it provided was offset by interfacial adhesion resistance, resulting in slower ink shrinkage and increased driving voltage requirements.

[0074] Based on the differences between the above embodiments and comparative examples in electrode structure and hydrophobic layer configuration, it can be concluded that: First, the core of this invention lies in the introduction of a support structure with a sloping surface. Compared to the conventional planar electrode in Comparative Example 1, this sloping structure, after the driving voltage is removed, can utilize the component of the gravitational force on the ink in the sloping direction and the surface tension gradient caused by the change in surface morphology to jointly form a directional capillary force pointing towards the pixel edge. This directional driving force provides an active reset path for ink shrinkage, thereby helping to reduce the driving voltage requirement, shorten the ink shut-off response time, and improve contrast by promoting more complete ink withdrawal from the display area.

[0075] Secondly, the slope angle is a key parameter for controlling the driving force. Examples 1-5 show that when the slope angle is set within the range of 10° to 30°, the resulting directional capillary force is moderate, providing sufficient driving force while avoiding difficulties in initial ink spreading or unstable flow due to excessive angle. Comparative Examples 2 (approximately 5° slope angle) and 3 (approximately 40° slope angle) serve as counterexamples: too small a slope angle results in a weak directional driving force, making it difficult to effectively overcome ink viscosity resistance; too large a slope angle hinders normal ink spreading and increases flow resistance.

[0076] Finally, the hydrophobic insulating layer is a key synergistic element in achieving the superior performance of the ramp structure. Comparing Example 3 and Comparative Example 4, it is evident that under identical ramp geometry, the hydrophobic insulating layer effectively reduces the solid-liquid interface adhesion between the ink and the electrode surface. Without this layer (as in Comparative Example 4), the resistance to ink flow on the ramp would significantly increase, thereby weakening or even negating the directional driving force advantage provided by the ramp structure. Therefore, the ramp structure and the hydrophobic insulating layer constitute a synergistic whole in this invention, jointly ensuring efficient and rapid electrowetting response under low voltage.

[0077] In summary, this invention provides a new solution for improving electrowetting display performance from a physical perspective through the synergistic design of a sloped electrode structure with a hydrophobic insulating layer within a specific tilt angle range. This effectively overcomes the limitations of traditional planar structures in terms of driving voltage, response speed, and contrast.

[0078] Obviously, the embodiments described above are merely some embodiments of this application, not all embodiments, and do not limit the patent scope of this application. This application can be implemented in many different forms; on the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this application.

Claims

1. An electrowetting display panel, characterized in that, include: lower base plate; A support structure disposed on the lower substrate has a sloping surface. Pixel electrodes formed on the sloping surface of the support structure.

2. The electrowetting display panel according to claim 1, characterized in that, The slope surface of the supporting structure is arched.

3. The electrowetting display panel according to claim 1, characterized in that, The slope surface of the supporting structure is inclined in a single direction.

4. The electrowetting display panel according to claim 1, characterized in that, The slope surface of the supporting structure has an inclination angle of 10° to 30°.

5. The electrowetting display panel according to claim 1, characterized in that, It also includes a hydrophobic insulating layer disposed on the pixel electrode.

6. The electrowetting display panel according to claim 5, characterized in that, The material of the support structure includes photoresist, and the slope surface is formed by exposure, development and thermal reflow of the photoresist through a halftone mask.

7. The electrowetting display panel according to claim 6, characterized in that, The pixel electrode is an indium tin oxide thin film with a thickness of 10~150 nm.

8. The electrowetting display panel according to claim 7, characterized in that, The support structure is formed by photoresist through thermal reflow, and the thickness of the support structure is 0.1~5μm.

9. A method for preparing an electrowetting display panel, characterized in that, Includes the following steps: Photoresist is coated onto the lower substrate; The photoresist is exposed and developed using a halftone mask to form a stepped pattern; The developed photoresist is subjected to thermal reflow treatment to form a support structure with a sloping surface; Pixel electrodes are formed on the sloping surface of the support structure. A hydrophobic insulating layer is formed on the pixel electrode.

10. A display device, characterized in that, Including the electrowetting display panel as described in any one of claims 1 to 8.

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