Electrowetting display device and preparation method and application thereof
By setting an adhesive layer between the dielectric layer and the bottom electrode, the problem of insufficient film bonding force during long-term use of the electrowetting display device is solved, and the stability and electrical performance of the device are improved.
Patent Information
- Application Number
- CN202510416394.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-08-15
AI Technical Summary
During the long-term use of existing electrowetted display devices, due to environmental factors, the bonding force between the film layers is insufficient, resulting in problems such as peeling and leakage of the film layers, affecting the reliability and service life of the device.
An adhesive layer is provided between the dielectric layer and the bottom electrode, and an adhesive layer composed of materials such as polyether-based polyurethane, aliphatic isocyanate-based polyurethane, and the thickness is 15-25 nm, which enhances the bonding force between the film layers.
Effectively reduce the peeling phenomenon between the film layers, improve the stability and aging electrical properties of the electrowetted display devices, and reduce leakage current and equivalent capacitance.
Smart Images
Figure CN120491304A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to an electrowetting display device, a preparation method thereof, and applications thereof. Background Art
[0002] Electrowetting refers to the phenomenon of changing the surface tension between the interface of liquid droplets and solids through an electric field, thereby changing the wettability between the two, causing the droplets to deform or displace. In the prior art, thin film layer structures are often used to enhance the performance of electrowetting display devices or improve the stability of the device. However, during long-term use, due to various external factors such as changes in ambient temperature and humidity, the bonding force between the film bases is affected, which in turn leads to problems such as film peeling, leakage or performance degradation, which greatly affects the reliability and service life of the device. Although the prior art improves the bonding force between the film bases by optimizing the film material or adopting a surface treatment process, the effect is limited. Although certain high-viscosity materials improve the bonding force between the film bases, they may introduce new problems, such as increasing the complexity of the process or affecting the display performance of the device. Summary of the Invention
[0003] To overcome at least one of the problems existing in the aforementioned prior art, one object of the present invention is to provide an electrowetting display device. A second object of the present invention is to provide a method for preparing the electrowetting display device. A third object of the present invention is to provide applications of the electrowetting display device. The electrowetting display device of the present invention effectively increases the bonding force between the dielectric layer and the bottom electrode of the electrowetting display device, reduces delamination between the film layers, and exhibits excellent stability and aging electrical properties.
[0004] To this end, the present invention adopts the following technical solutions:
[0005] A first aspect of the present invention provides an electrowetting display device, comprising a bottom electrode, an adhesive layer, a dielectric layer, a perfluoropolymer layer, a high-pixel wall structure, and a top electrode stacked in sequence; the high-pixel wall structure is filled with ink.
[0006] Preferably, the adhesive layer is composed of at least one material selected from polyether polyurethane, aliphatic isocyanate polyurethane, and diphenyldihydroxysilane. Further preferably, the adhesive layer is composed of at least one material selected from polyether polyurethane and aliphatic isocyanate polyurethane. Even more preferably, the adhesive layer is composed of SurPass3000.
[0007] Preferably, the thickness of the adhesive layer is 15 to 25 nm. More preferably, the thickness of the adhesive layer is 15 to 20 nm.
[0008] Preferably, the material composition of the dielectric layer is photoresist. Further preferably, the material composition of the dielectric layer is ultraviolet photoresist. Even more preferably, the material composition of the dielectric layer is HN-018N.
[0009] Preferably, the thickness of the dielectric layer is 350 to 480 nm. Further preferably, the thickness of the dielectric layer is 350 to 450 nm. Even more preferably, the thickness of the dielectric layer is 350 to 400 nm.
[0010] Preferably, the material composition of the perfluoropolymer layer is perfluoropolymer. Further preferably, the material composition of the perfluoropolymer layer is amorphous polytetrafluoroethylene. Even more preferably, the material composition of the perfluoropolymer layer is Hyflon AD 40.
[0011] Preferably, the thickness of the perfluoropolymer layer is 300 to 480 nm. More preferably, the thickness of the perfluoropolymer layer is 350 to 420 nm. Even more preferably, the thickness of the perfluoropolymer layer is 400 to 420 nm.
[0012] Preferably, the material composition of the high-pixel wall structure is photoresist. Further preferably, the material composition of the high-pixel wall structure is UV photoresist. Even more preferably, the material composition of the high-pixel wall structure is HN-008N.
[0013] Preferably, the thickness of the high-pixel wall structure is 2.5 to 4.0 μm. Further preferably, the thickness of the high-pixel wall structure is 2.5 to 3.5 μm. Even more preferably, the thickness of the high-pixel wall structure is 3.5 μm.
[0014] Preferably, the bottom electrode and the top electrode are both made of tin-doped indium oxide (ITO) glass, and both have a thickness of 20 to 30 nm.
[0015] A second aspect of the present invention provides a method for preparing the electrowetting display device according to the first aspect of the present invention, comprising the following steps:
[0016] (1) preparing an adhesive layer on the bottom electrode by spin coating;
[0017] (2) coating the adhesive layer with a conductive solution, pre-curing the solution, and curing the solution by ultraviolet light exposure using a photoresist to obtain a dielectric layer;
[0018] (3) applying a perfluoropolymer (Hyflon) solution on the dielectric layer by spin coating, curing, and etching to obtain a perfluoropolymer layer;
[0019] (4) applying a photoresist on the perfluoropolymer layer by spin coating, curing, and developing to obtain a high-pixel wall structure;
[0020] (5) The ink is pushed into the pixel grid of the high pixel wall structure, and tin-doped indium oxide glass is used as the top electrode. The ink is fixed with a glue frame, and UV glue is applied to the periphery of the glue frame and UV-cured to obtain the electrowetting display device.
[0021] Preferably, in step (1), the spin coating speed of the spin coating method is 3000-3500 rpm, and the spin coating acceleration of the spin coating method is 1000-1200 rad / s 2 , the spin coating time of the spin coating method is 30 to 40 seconds. Further preferably, in step (1), the spin coating speed of the spin coating method is 3000 to 3200 rpm, and the spin coating acceleration of the spin coating method is 1000 to 1100 rad / s 2 The spin coating time of the spin coating method is 30 to 35 seconds.
[0022] Preferably, in step (2), the pre-curing temperature is 100-120°C, and the pre-curing time is 3-5 minutes. Further preferably, in step (2), the pre-curing temperature is 100-110°C, and the pre-curing time is 3-4 minutes.
[0023] Preferably, in step (3), the spin coating speed of the spin coating method is 720-850 rpm, and the spin coating acceleration of the spin coating method is 300-400 rad / s 2 The spin coating time of the spin coating method is 60 to 70 seconds. Further preferably, the spin coating speed of the spin coating method is 720 to 800 rpm, and the spin coating acceleration of the spin coating method is 300 to 350 rad / s 2 The spin coating time of the spin coating method is 60 to 65 seconds.
[0024] The third aspect of the present invention provides an application of the electrowetting display device according to the first aspect of the present invention or the electrowetting display device prepared according to the method for preparing the electrowetting display device according to the second aspect of the present invention in the semiconductor field.
[0025] Compared with the prior art, the present invention has the following beneficial effects:
[0026] The present invention connects an adhesive layer between the dielectric layer and the bottom electrode. The leakage current and equivalent capacitance of the electrowetting display device with an adhesive layer are lower than those of the device without an adhesive layer, indicating that the adhesive layer can effectively increase the bonding force between the film layers and reduce the structural defects of the device. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention will be further described below with reference to the accompanying drawings, embodiments and comparative examples, wherein:
[0028] Figure 1These are static contact angle photos of ITO surfaces of ITO, Comparative Example 1, and Examples 1 to 4.
[0029] Figure 2 Graph showing transmittance of the ITO glass of Example 1, Example 3, and Comparative Example 1.
[0030] Figure 3 These are optical capture images of the pixel grids of the electrowetting display devices of Examples 1 to 4 and Comparative Example 1 when a DC voltage of 16V is applied.
[0031] Figure 4 1 and 2 are IV characteristic curves of the electrowetting display devices of Examples 1 to 4 and Comparative Example 1.
[0032] Figure 5 CV characteristic curves of the electrowetting display devices of Examples 1 to 4 and Comparative Example 1.
[0033] Figure 6 These are surface morphologies of the electrowetting display devices of Comparative Example 1, Example 1, and Example 4 after aging for 0 h, 24 h, and 48 h.
[0034] Figure 7 The IV characteristic curves of the electrowetting display devices of Comparative Example 1, Example 1, and Example 4 after aging for 0 h, 24 h, and 48 h. DETAILED DESCRIPTION
[0035] The present invention is further described in detail below through specific examples, comparative examples and tables, but is not limited to all discussions and data.
[0036] It is particularly important to emphasize that, unless otherwise specified, the raw materials, reagents, or devices in the present invention can be obtained from conventional commercial channels.
[0037] Example 1:
[0038] A method for preparing an electrowetting display device (using SurPass 3000 solution as a bonding layer) comprises the following steps:
[0039] (1) Spin coating the SurPass 3000 solution evenly on the ITO glass at a speed of 3000 rpm and an acceleration of 1000 rad / s. 2 The spin coating time was 30s. After rinsing the surface with water for 30s, the surface was blown dry with a nitrogen gun and placed on a hot plate for curing. The curing temperature was 180°C and the curing time was 5min to obtain a 15nm thick bonding layer.
[0040] (2) Spin coating the HN-018N solution evenly on the adhesive layer at a speed of 1750 rpm and an acceleration of 800 rad / s. 2 The spin coating time is 65s, and the film is placed on a hot plate for pre-curing. The pre-curing temperature is 110°C, and the pre-curing time is 3min10s. After pre-curing, the photoresist is exposed to UV light for curing. The UV wavelength is 365nm and the exposure intensity is 17W / cm 2 , curing time 35s, and then put it into a dust-free oven for main curing. The main curing temperature is 210℃, and the main curing time is 60min to obtain a 400nm HN-018N film.
[0041] (3) Hyflon powder was dissolved in perfluoropolyether (Galden D02) solvent to prepare a 3% mass concentration of Hyflon solution; the Hyflon solution was evenly coated on the HN-018N film by spin coating at a spin coating speed of 720 rpm and a spin coating acceleration of 300 rad / s. 2 The spin coating time was 65s. After the spin coating was completed, it was allowed to stand for 5 minutes and placed on a hot plate for pre-curing. The pre-curing temperature was 85°C and the pre-curing time was 1.5 minutes. After pre-curing, it was placed in a dust-free oven for main curing. The main curing temperature was 185°C and the main curing time was 30 minutes. A 400nm Hyflon film was obtained. Oxygen was introduced and the entire surface of the Hyflon was modified using an ion etcher (RIE). The etching power was 5W and the etching time was 6s to obtain a hydrophilic Hyflon layer.
[0042] (4) HN-008N photoresist was evenly coated on the hydrophilic Hyflon layer using a multi-step spin coating method, with the first step spin coating speed being 500 rpm and the second step spin coating speed being 1100 rpm. The layer was then placed on a hot plate for pre-curing at a temperature of 110°C for 2.5 minutes. A pixel wall was produced using a photolithography machine and a mask, with a photolithography time of 18 seconds and a pixel grid size of 170 μm*170 μm. A secondary curing was then performed at a temperature of 110°C for 2.5 minutes. After the secondary curing, a development operation was performed. The photoresist was immersed in a 0.4% KOH solution for 1 minute and shaken for 1 minute to fully dissolve the photoresist in the pixel grid. The photoresist was taken out and immersed in a new 0.4% KOH solution for secondary development. After the secondary development, the photoresist was deep cleaned by RIE. The photoresist was then placed in a new 0.4% KOH solution for a third development. After the development was completed, the photoresist was transferred to a dust-free oven for high-temperature reflow at a temperature of 210°C and a baking time of 1 hour. After the high-temperature reflow, the hydrophobicity of the Hyflon layer was restored to obtain a 3.5μm high-pixel wall structure.
[0043] (5) The device structure prepared above was placed in a tilted container, and the ink was slowly pushed into the pixel grid using pure water. An ITO glass that had been irradiated with ultraviolet light for 10 minutes was then used as the top electrode and fixed on top of the device using a plastic frame of appropriate size. UV glue was then applied to the outer periphery of the plastic frame for secondary packaging. The device was then placed under ultraviolet light for 10 minutes to cure, resulting in an electrowetting display device. This device was labeled SurPass 3000.
[0044] Example 2:
[0045] A method for preparing an electrowetting display device (ITO glass is treated with an ultraviolet process (UV process) and SurPass 3000 solution is used as a bonding layer), comprising the following steps:
[0046] (1) ITO glass is exposed to ultraviolet light for 10 minutes, i.e., UV process, to increase the hydrophilicity of the ITO glass surface.
[0047] (2) Spin coating the SurPass 3000 solution evenly on the ITO glass at a speed of 3000 rpm and an acceleration of 1000 rad / s. 2 The spin coating time was 30s. After rinsing the surface with water for 30s, the surface was blown dry with a nitrogen gun and placed on a hot plate for curing. The curing temperature was 180°C and the curing time was 5min to obtain a 15nm thick bonding layer.
[0048] (3) Spin coating the HN-018N solution evenly on the adhesive layer at a speed of 1750 rpm and an acceleration of 800 rad / s. 2 The spin coating time is 65s, and the film is placed on a hot plate for pre-curing. The pre-curing temperature is 110°C, and the pre-curing time is 3min10s. After pre-curing, the photoresist is exposed to UV light for curing. The UV wavelength is 365nm and the exposure intensity is 17W / cm 2 , curing time 35s, and then put it into a dust-free oven for main curing. The main curing temperature is 210℃, and the main curing time is 60min to obtain a 400nm HN-018N film.
[0049] (4) Hyflon powder was dissolved in perfluoropolyether (Galden D02) solvent to prepare a 3% mass concentration of Hyflon solution; the Hyflon solution was evenly coated on the HN-018N film by spin coating at a spin coating speed of 720 rpm and a spin coating acceleration of 300 rad / s. 2The spin coating time was 65s. After the spin coating was completed, it was allowed to stand for 5 minutes and placed on a hot plate for pre-curing. The pre-curing temperature was 85°C and the pre-curing time was 1.5 minutes. After pre-curing, it was placed in a dust-free oven for main curing. The main curing temperature was 185°C and the main curing time was 30 minutes. A 400nm Hyflon film was obtained. Oxygen was introduced and the entire surface of the Hyflon was modified using an ion etcher (RIE). The etching power was 5W and the etching time was 6s to obtain a hydrophilic Hyflon layer.
[0050] (5) HN-008N photoresist was evenly coated on the hydrophilic Hyflon layer using a multi-step spin coating method, with the first step spin coating speed being 500 rpm and the second step spin coating speed being 1100 rpm. The layer was then placed on a hot plate for pre-curing at a temperature of 110°C for 2.5 minutes. A pixel wall was prepared using a photolithography machine and a mask, with a photolithography time of 18 seconds and a pixel grid size of 170 μm*170 μm. A secondary curing was then performed at a temperature of 110°C for 2.5 minutes. After the secondary curing, a development operation was performed. The photoresist was immersed in a 0.4% KOH solution for 1 minute and shaken for 1 minute to fully dissolve the photoresist in the pixel grid. The photoresist was taken out and immersed in a new 0.4% KOH solution for secondary development. After the secondary development, the photoresist was deep cleaned by RIE. The photoresist was then placed in a new 0.4% KOH solution for a third development. After the development was completed, the photoresist was transferred to a dust-free oven for high-temperature reflow at a temperature of 210°C and a baking time of 1 hour. After the high-temperature reflow, the hydrophobicity of the Hyflon layer was restored to obtain a 3.5μm high-pixel wall structure.
[0051] (6) The device structure prepared above was placed in a tilted container, and the ink was slowly pushed into the pixel grid using pure water. An ITO glass that had been irradiated with UV light for 10 minutes was then used as the top electrode and fixed to the top of the device using a plastic frame of appropriate size. UV glue was then applied to the outer periphery of the plastic frame for secondary packaging. The device was then placed under UV light for 10 minutes to cure, resulting in an electrowetting display device. This was labeled UV_SurPass 3000.
[0052] Example 3:
[0053] A method for preparing an electrowetting display device (using AR 300-80new solution as a bonding layer) comprises the following steps:
[0054] (1) Use spin coating to evenly coat AR 300-80new solution on ITO glass at a spin coating speed of 4000 rpm and a spin coating acceleration of 1000 rad / s 2The spin coating time was 60s, and the film was placed on a hot plate for curing at a curing temperature of 100°C and a curing time of 3min to obtain a 15nm thick bonding layer.
[0055] (2) Spin coating the HN-018N solution evenly on the adhesive layer at a speed of 1750 rpm and an acceleration of 800 rad / s. 2 The spin coating time is 65s, and the film is placed on a hot plate for pre-curing. The pre-curing temperature is 110°C, and the pre-curing time is 3min10s. After pre-curing, the photoresist is exposed to UV light for curing. The UV wavelength is 365nm and the exposure intensity is 17W / cm 2 , curing time 35s, and then put it into a dust-free oven for main curing. The main curing temperature is 210℃, and the main curing time is 60min to obtain a 400nm HN-018N film.
[0056] (3) Hyflon powder was dissolved in Galden D02 solvent to prepare a 3% mass concentration of Hyflon solution; the Hyflon solution was evenly coated on the HN-018N film by spin coating at a spin coating speed of 720 rpm and a spin coating acceleration of 300 rad / s. 2 , the spin coating time is 65s; after the spin coating is completed, let it stand for 5 minutes, and then place the device on a hot plate for pre-curing, the pre-curing temperature is 85℃, and the pre-curing time is 1.5min; after pre-curing, place it in a dust-free oven for main curing, the main curing temperature is 185℃, and the main curing time is 30min to obtain a 400nm Hyflon film. Use RIE to introduce oxygen and modify the entire surface of the Hyflon. The etching power is 5W and the etching time is 6s to obtain a hydrophilic Hyflon layer.
[0057] (4) HN-008N photoresist was evenly coated on the hydrophilic Hyflon layer using a multi-step spin coating method, with the first step spin coating speed being 500 rpm and the second step spin coating speed being 1100 rpm; the layer was then placed on a hot plate for pre-curing, with the pre-curing temperature being 110°C and the pre-curing time being 2.5 min; a photolithography machine and a mask were then used to produce a pixel wall, with the photolithography time being 18 s and the pixel grid size of the mask being 170 μm*170 μm; a secondary curing was performed, with the curing temperature being 110°C and the curing time being 2.5 min; a development operation was performed after the secondary curing. The photoresist was immersed in a 0.4% KOH solution for 1 minute, shaken for 1 minute to fully dissolve the photoresist in the pixel grid, taken out, and immersed in a new 0.4% KOH solution for secondary development; after the secondary development, it was subjected to RIE for deep cleaning; and then placed in a new 0.4% KOH solution for a third development operation; after the development was completed, it was transferred to a dust-free oven for high-temperature reflow at an oven temperature of 210°C and a baking time of 1 hour. After high-temperature reflow, the Hyflon layer regained its hydrophobicity; and a 3.5μm high-pixel wall structure was obtained.
[0058] (5) The resulting high-pixel wall structure was placed in a tilted container, and the ink was slowly pushed into the pixel grid using pure water. An ITO glass that had been irradiated with UV light for 10 minutes was used as the top electrode and fixed on top using a plastic frame of appropriate size. UV glue was applied to the outer periphery of the plastic frame for secondary packaging, and the device was cured under UV light for 10 minutes to produce an electrowetting display device. This device was labeled AR 300-80new.
[0059] Example 4:
[0060] A method for preparing an electrowetting display device (ITO glass is treated with an ultraviolet process (UV process) and an AR 300-80 new solution is used as a bonding layer), comprising the following steps:
[0061] (1) ITO glass is exposed to ultraviolet light for 10 minutes, i.e., UV process, to increase the hydrophilicity of the ITO glass surface.
[0062] (2) Use spin coating to evenly coat the AR 300-80 new solution on the above ITO glass at a spin coating speed of 4000 rpm and a spin coating acceleration of 1000 rad / s. 2 The spin coating time was 60s, and the film was placed on a hot plate for curing at a curing temperature of 100°C and a curing time of 3min to obtain a 15nm thick bonding layer.
[0063] (3) Spin coating the HN-018N solution evenly on the adhesive layer at a speed of 1750 rpm and an acceleration of 800 rad / s. 2The spin coating time is 65s, and the film is placed on a hot plate for pre-curing. The pre-curing temperature is 110°C, and the pre-curing time is 3min10s. After pre-curing, the photoresist is exposed to UV light for curing. The UV wavelength is 365nm and the exposure intensity is 17W / cm 2 , curing time is 35s; then put it into a dust-free oven for main curing, the main curing temperature is 210℃, the main curing time is 60min, and a 400nm HN-018N film is obtained.
[0064] (4) Hyflon powder was dissolved in Galden D02 solvent to prepare a 3% mass concentration of Hyflon solution; the Hyflon solution was evenly coated on the HN-018N film by spin coating at a spin coating speed of 720 rpm and a spin coating acceleration of 300 rad / s. 2 , the spin coating time is 65s; after the spin coating is completed, let it stand for 5 minutes, and then place the device on a hot plate for pre-curing, the pre-curing temperature is 85℃, and the pre-curing time is 1.5min; after pre-curing, place it in a dust-free oven for main curing, the main curing temperature is 185℃, and the main curing time is 30min to obtain a 400nm Hyflon film. Use RIE to introduce oxygen and modify the entire surface of the Hyflon. The etching power is 5W and the etching time is 6s to obtain a hydrophilic Hyflon layer.
[0065] (5) HN-008N photoresist was evenly coated on the hydrophilic Hyflon layer using a multi-step spin coating method, with the first step spin coating speed being 500 rpm and the second step spin coating speed being 1100 rpm; the layer was then placed on a hot plate for pre-curing, with the pre-curing temperature being 110°C and the pre-curing time being 2.5 min; a photolithography machine and a mask were then used to produce a pixel wall, with the photolithography time being 18 s and the pixel grid size of the mask being 170 μm*170 μm; a secondary curing was performed, with the curing temperature being 110°C and the curing time being 2.5 min; a development operation was performed after the secondary curing. The photoresist was immersed in a 0.4% KOH solution for 1 minute, shaken for 1 minute to fully dissolve the photoresist in the pixel grid, taken out, and immersed in a new 0.4% KOH solution for secondary development; after the secondary development, it was subjected to RIE for deep cleaning; and then placed in a new 0.4% KOH solution for a third development operation; after the development was completed, it was transferred to a dust-free oven for high-temperature reflow at an oven temperature of 210°C and a baking time of 1 hour. After high-temperature reflow, the Hyflon layer regained its hydrophobicity; and a 3.5μm high-pixel wall structure was obtained.
[0066] (6) The resulting high-pixel wall structure was placed in a tilted container, and pure water was used to slowly push ink into the pixel grid. An ITO glass that had been irradiated with UV light for 10 minutes was used as the top electrode and fixed on top using a plastic frame of appropriate size. UV glue was applied to the outer periphery of the plastic frame for secondary packaging, and the device was cured under UV light for 10 minutes to produce an electrowetting display device. This device was labeled UV_AR 300-80new.
[0067] Comparative Example 1:
[0068] A method for preparing an electrowetting display device, omitting step (2) of Example 2. The remaining steps and amounts are the same as those of Example 2. Labeled as UV_ITO.
[0069] Material performance test:
[0070] The static contact angle, transmittance test, aperture ratio test, IV test, CV test, and aging electrical properties of the ITO surface of the electrowetting display devices obtained in Examples 1 to 4 and Comparative Example 1 were tested. The test standards are as follows:
[0071] (1) The static contact angles of ITO, Comparative Example 1, and ITO surfaces obtained from Examples 1 to 4 were measured. Figure 1 Shown, wherein UV process is not carried out, and the ITO surface static contact angle of the ITO of bonding layer is not set is 36.5 °.Comparative example 1 has carried out UV process, and bonding layer is not set, and ITO surface static contact angle is 8.1 °, is super hydrophilic state.Example 3 does not carry out UV process, but arranges AR 800-30new bonding layer, and its ITO surface static contact angle is 50.5 °, more than carrying out UV process, the ITO surface of the ITO of bonding layer is not set is more hydrophobic (contact angle increases 14 °).Example 1 does not carry out UV process, but arranges SurPass 3000 bonding layer, and ITO surface static contact angle is 26.7 °, more than carrying out UV process, the ITO surface of the ITO of bonding layer is not set is more hydrophilic (contact angle reduces 9.8 °).Example 2, embodiment 4 carry out UV process, and bonding layer is set, and ITO surface static contact angle all increases, and surface all becomes more hydrophobic.
[0072] (2) The transmittance of the ITO glass of the electrowetting display device of Example 1, Example 3 and Comparative Example 1 was tested. The test results are as follows: Figure 2 After analysis, the transmittance of the electrowetting display devices of Example 1, Example 3, and Comparative Example 1 is about 90% in the visible light wavelength range, and the transmittance overlap at each wavelength is very high, proving that setting the adhesive layer will not affect the transmittance of the device.
[0073] (3) The aperture ratio of the electrowetting display devices of Examples 1 to 4 and Comparative Example 1 was tested and optical photos were taken, as shown in FIG. Figure 3 As shown, when a 16V DC voltage was applied to the upper and lower plates of the electrowetting display devices of Examples 1 to 4 and Comparative Example 1, the aperture ratio of each device was about 56%. The electrowetting display devices of Examples 1 to 4 and Comparative Example 1 were subjected to IV and CV tests, that is, a DC voltage of 0-16V was applied to the devices, and the leakage current and equivalent capacitance of the devices were measured. The results are shown in FIG. Figure 4 、 Figure 5 As shown in the results, it can be seen that the leakage current and equivalent capacitance of the electrowetting display devices of Examples 1 to 4 in which the bonding layer is set are lower than those of Comparative Example 1 in which the bonding layer is not set, which indicates that setting the bonding layer can effectively increase the bonding force between the film layers and reduce the defects of the device structure.
[0074] (4) The electrowetting display devices of Comparative Example 1 and Examples 1 to 4 were placed in an aging box with constant temperature and humidity (50°C, 50% humidity) and a continuous pulse voltage (16V) for aging electrical performance testing. The surface morphology after aging for 0h, 24h, and 48h was observed ( Figure 6 ), as can be seen from the figure, compared with Comparative Example 1, the surface of the electrowetting display device of Example 1 with a SurPass 3000 bonding layer has the smallest electrode corrosion area. Secondly, the electrowetting display device of Example 4, which has a SurPass3000 bonding layer, has only one electrode corrosion on its surface after aging for 24 hours, and no additional electrode corrosion occurs after aging for 48 hours. Compared with Comparative Example 1 without a bonding layer, the device has better stability and aging resistance. Compared with Comparative Example 1, Examples 2 and 3 have severe electrode corrosion in some areas after aging for 24 hours and 48 hours, but the total electrode corrosion area of Example 2 is significantly smaller than that of Example 3 and Comparative Example 1, and has better aging resistance. The electrowetting display devices of Comparative Example 1 and Examples 1 to 4 were subjected to IV tests after aging for 0 hours, 24 hours, and 48 hours, respectively. The results are as follows Figure 7 As shown in the results, the leakage current of the electrowetting display device of Example 1 using SurPass 3000 as the bonding layer is the lowest, which is consistent with the conclusion obtained from the surface morphology characterization.
[0075] The present invention utilizes a binder to regulate the static contact angle of an indium tin oxide (ITO) glass surface, thereby enhancing the compatibility between the ITO glass and the HN-018 photoresist heterogeneous layer and improving the electrical aging resistance of an electrowetting device. The above experiments show that different types of binders have different optimal static contact angles on the ITO surface. For Comparative Example 1 (UV_ITO), the contact angle significantly decreased from 36.5° (ITO) to 8.1° (UV_ITO) after UV treatment. However, after 48 hours of aging, the electrowetting display device exhibited small-area electrode corrosion and a significant increase in leakage current.
[0076] For the Surpass 3000 bonding layer, the contact angle decreases from 36.5° (ITO) to 26.7° (Surpass3000). The electrowetting display device in Example 1 achieves the best aging resistance. After 48 hours, there is essentially no electrode corrosion on the panel, and the leakage current is very low. However, after using the UV process for Surpass 3000, the contact angle increases to 38.9° (UV_SurPass3000). The aging resistance of the electrowetting display device in Example 2 decreases significantly, the type of electrode failure is typical pitting corrosion, and the leakage current approaches zero.
[0077] For the AR 300-80new adhesive layer, the contact angle increased significantly after the adhesive layer was applied on the ITO glass, from 36.5° (ITO) to 50.5° (AR 300-80new). The electrowetting display device of Example 3 showed pitting after aging for 48 hours. Figure 6 (d), the leakage current approaches zero; after adopting the UV process, its contact angle increases to 58.9° (UV_AR 300-80new). At this time, the electrode failure type of the electrowetting display device in Example 4 is small-area electrode corrosion. Its aging performance is similar to that of UV_ITO, and the leakage current is slightly larger than that of UV_ITO.
[0078] In summary, to improve the bonding strength between ITO glass and photoresist, the static contact angle of the ITO surface on the ITO glass should be optimized. Research in this paper shows that reducing the static contact angle of the ITO surface helps improve aging performance. However, a wetting angle that is too small (UV_ITO) or too large (UV_AR 300-80new) can cause electrode corrosion and reduce aging life. When the static contact angle of the ITO surface is adjusted to 26.7° (SurPass 3000), the hydrophobic layer and photoresist bond best, exhibiting the best aging performance and significantly extending the life of the electrowetting device.
Claims
1. An electrowetting display device, characterized in that: It includes a bottom electrode, an adhesive layer, a dielectric layer, a perfluoropolymer layer, a high-pixel wall structure, and a top electrode stacked in sequence; The high-pixel wall structure is filled with ink.
2. The electrowetting display device according to claim 1, wherein The material composition of the bonding layer is selected from at least one of polyether polyurethane, aliphatic isocyanate polyurethane, and diphenyldihydroxysilane.
3. The electrowetting display device according to claim 1, wherein: The thickness of the bonding layer is 15 to 25 nm.
4. The electrowetting display device according to claim 1, characterized in that The dielectric layer is made of photoresist with a thickness of 350 to 480 nm. And / or, the material composition of the perfluoropolymer layer is perfluoropolymer, and the thickness is 300 to 480 nm; And / or, the material composition of the high-pixel wall structure is photoresist, with a thickness of 2.5-4.0 μm.
5. The electrowetting display device according to claim 1, characterized in that: The bottom electrode and the top electrode are both made of tin-doped indium oxide glass, and both have a thickness of 20 to 30 nm.
6. The method for preparing an electrowetting display device according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) preparing an adhesive layer on the bottom electrode by spin coating; (2) coating the adhesive layer with a conductive solution, pre-curing the solution, and curing the solution by ultraviolet light exposure using a photoresist to obtain a dielectric layer; (3) applying a perfluoropolymer solution on the dielectric layer film by spin coating, curing, and etching to obtain a perfluoropolymer layer; (4) applying a photoresist on the perfluoropolymer layer by spin coating, curing, and developing to obtain a high-pixel wall structure; (5) The ink is pushed into the pixel grid of the high pixel wall structure, and tin-doped indium oxide glass is used as the top electrode. The ink is fixed with a glue frame, and UV glue is applied to the periphery of the glue frame and UV-cured to obtain the electrowetting display device.
7. The method for preparing an electrowetting display device according to claim 6, wherein: In step (1), the spin coating speed of the spin coating method is 3000-3500 rpm, and the spin coating acceleration of the spin coating method is 1000-1200 rad / s 2 The spin coating time of the spin coating method is 30 to 40 seconds.
8. The method for preparing an electrowetting display device according to claim 6, wherein: In step (2), the pre-curing temperature is 100-120° C., and the pre-curing time is 3-5 minutes.
9. The method for preparing an electrowetting display device according to claim 6, wherein: In step (3), the spin coating speed of the spin coating method is 720-850 rpm, and the spin coating acceleration of the spin coating method is 300-400 rad / s 2 The spin coating time of the spin coating method is 60 to 70 seconds.
10. Use of the electrowetting display device according to any one of claims 1 to 5 or the electrowetting display device prepared by the method for preparing the electrowetting display device according to claims 6 to 9 in the semiconductor field.