An asymmetrically enhanced planar electrode alternating current electroluminescent device and its applications

Abstract

The present invention relates to an asymmetrically enhanced planar electrode alternating current electroluminescent device and its applications. The asymmetrically enhanced planar electrode alternating current electroluminescent device sequentially includes, from bottom to top: a substrate, an electrode, a light-emitting active layer, and a low-impedance bridge layer; wherein, the electrode includes electrode A and electrode B which are spaced apart on the substrate, the light-emitting active layer includes a light-emitting active layer A covering electrode A and a light-emitting active layer B covering electrode B, the impedances of the light-emitting active layer A and the light-emitting active layer B are different, and the impedance of the low-impedance bridge layer is much smaller than that of the light-emitting active layer. The device with this structure can not only retain the characteristics of the planar electrode alternating current electroluminescent device structure, but also solve the problems of high driving voltage and difficulty in patterning / integration of the existing planar electrode alternating current electroluminescent devices. The device can be easily made into an information encryption device or an intelligent and wearable display device only by adjusting the electrode pattern.

Description

Technical Field

[0001] The present invention relates to the technical field of electroluminescence, and in particular to an asymmetrically enhanced planar electrode alternating current electroluminescent device and its application. Background Art

[0002] Electroluminescence, also known as field luminescence, abbreviated as EL, was first discovered by French scientist G. Destriau in 1936, and it is a technology with a history of nearly eighty years. Electroluminescent devices have great market value and application prospects in the fields of lighting and display. Compared with direct current-driven electroluminescent devices, alternating current-driven electroluminescent devices have the advantages of adjustable frequency and phase, effectively avoiding charge accumulation, reducing electrochemical reactions between electrodes and the emission layer, and being easy to integrate with household power supplies. Among alternating current-driven electroluminescent devices, alternating current thin film electroluminescence (AC-TFEL) has outstanding and attractive characteristics in some aspects, such as low cost, convenient large-area processing performance, excellent mechanical and environmental durability, etc., so it has broad application prospects.

[0003] Traditional alternating current electroluminescent devices mostly have a sandwich structure, with electrodes on both sides of the active layer to form an electric field perpendicular to the plane of the device. In 2017, the Meng research group proposed a novel planar electrode alternating current electroluminescent device. The structure of this novel light-emitting device consists of two planar electrodes of equal size at the bottom, a middle light-emitting active layer, and a low-impedance material at the top. This structure makes it possible to realize multifunctional devices for electroluminescence and visual sensing. On the one hand, researchers have done a series of work on visual pressure, temperature, impedance, magnetic, and liquid sensors based on planar electrode alternating current-driven EL devices. On the other hand, researchers have expanded this structure using organic light-emitting materials and quantum dot light-emitting materials, and developed planar electrode alternating current-driven organic light-emitting diodes and quantum dot light-emitting diodes; they have also further improved the geometric structure and designed alternating current-driven color-tunable organic light-emitting triodes, three-phase current-driven electroluminescent devices, and digitally programmable organic light-emitting diodes.

[0004] However, the current work mainly focuses on promoting the planar electrode structure to different applications, while ignoring its inherent defects. Firstly, the driving voltage of planar structure electroluminescent devices is twice that of the sandwich structure; secondly, the arrangement of planar electrodes also makes it difficult to integrate patterns / arrays for display, which limits its further application. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides an asymmetrically enhanced planar electrode alternating current electroluminescent device and its application, aiming to solve the problems of high driving voltage and difficulty in patterning / integration of existing planar electrode alternating current electroluminescent devices.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect of the present invention, there is provided an asymmetrically enhanced planar electrode alternating current electroluminescent device, as Figure 1 shown, which sequentially includes, from bottom to top: a substrate, an electrode, a light-emitting active layer, and a low-impedance bridge layer; wherein, the electrode includes electrode A and electrode B spaced apart on the substrate, the light-emitting active layer includes a light-emitting active layer A covering electrode A and a light-emitting active layer B covering electrode B, and the impedances of the light-emitting active layer A and the light-emitting active layer B are different.

[0008] That is to say, an alternating current electroluminescent device with an asymmetrically enhanced planar structure provided by the present invention includes a substrate, a planar electrode layer, an asymmetric light-emitting active layer, and a low-impedance bridge layer. The planar electrode layer includes electrode A and electrode B, and electrode A and electrode B are disconnected. Here, it is assumed that electrode A is a background electrode and electrode B is a display electrode. The asymmetric light-emitting active layer includes a light-emitting active layer A and the light-emitting active layer B. The light-emitting active layer can be various light-emitting active layers required. At least one of the thickness, material, area, number of layers, etc. of the two light-emitting active layers is different, and preferably the areas are different, so that the impedances of the light-emitting active layer A and the light-emitting active layer B are different. The low-impedance bridge layer is disposed on the surface of the asymmetric light-emitting active layer and is made of a material with an impedance value much smaller than that of the asymmetric light-emitting active layer.

[0009] It should be noted that the key of the present invention lies in the innovative improvement of the light-emitting active layer in the planar electrode alternating current electroluminescent device, that is, different light-emitting active layers are respectively disposed on the two electrodes (at least one of a series of parameters that can change the impedance such as the area, material, thickness, number of layers, etc. of the two light-emitting active layers is different, which is not limited herein, and preferably the areas are different). The basic principle of this design is that the planar electrode alternating current electroluminescent device can be simplified into three impedance units connected in series, as Figure 1 shown: Z1 represents the impedance of the light-emitting active layer A covered between electrode A and the low-impedance bridge layer, Z2 represents the impedance within the low-impedance bridge layer, and Z3 represents the impedance of the light-emitting active layer B covered between electrode B and the low-impedance bridge layer. Based on the fact that different impedances have different voltage divisions and different voltage divisions result in different brightnesses, as much as possible, the impedance of Z3 is increased and the impedance of Z1 is decreased, so that the input voltage is more concentrated at the display end to enhance its brightness for display. At this time, not only can the characteristics of the structure of the planar electrode alternating current electroluminescent device be retained, but also the problems of high driving voltage and difficulty in patterning / integration of the existing planar electrode alternating current electroluminescent device can be solved.

[0010] It should also be noted that the light-emitting active layer in the device with this structure of the present invention can be in accordance with the structure of the light-emitting active layer (i.e., the part excluding the electrodes) in a sandwich AC electroluminescent device, such as the order and materials of a dielectric layer, an electron transport layer / injection layer, a hole transport layer / injection layer, a hole generation layer, etc. In addition, other functional layers can be added according to different usage requirements, which are not specifically limited herein.

[0011] It should also be noted that the preparation method of each layer (electrode, light-emitting active layer, and low-impedance bridge layer) of the device with this structure of the present invention can adopt the common film-forming methods in the art, such as spin coating, blade coating, screen printing, evaporation, spraying, sputtering, chemical vapor deposition, atomic layer deposition, etc., which are not specifically limited herein.

[0012] It should also be noted that the device with this structure of the present invention can also be prepared into a flexible and stretchable device. When made into a stretchable device, the corresponding electrodes, light-emitting active layer, and low-impedance bridge layer, etc. all need to have a certain degree of flexibility and stretchability.

[0013] Finally, it should also be noted that this asymmetrically enhanced planar electrode AC electroluminescent device is applicable not only to inorganic AC thin-film electroluminescence (AC-TFEL), but also to other AC electroluminescent devices such as AC organic electroluminescence (AC-OLED), AC perovskite electroluminescence (AC-PeLED), AC quantum dot electroluminescence (AC-QLED), etc., which are not limited herein. In particular, when applicable to the above devices, some changes will occur in the device structure, which will be introduced in detail in the following solutions.

[0014] Preferably, in the present invention, by adjusting the areas of the two light-emitting active layers, the impedances of the light-emitting active layer A and the light-emitting active layer B are made different. Using the area strategy is the most convenient. Only need to etch electrodes A and B with different area sizes on the electrode, and then deposit the corresponding light-emitting active layers on this planar electrode. That is, this asymmetrically enhanced planar electrode AC electroluminescent device includes: a substrate, an electrode formed on the substrate, a light-emitting active layer formed on the electrode and on the substrate not covered by the electrode, and a low-impedance bridge layer formed on the light-emitting active layer; wherein, the electrode includes electrode A and electrode B, electrode A and electrode B are spaced apart and formed on the substrate, the area of the upper surface of electrode A and the area of the upper surface of electrode B are different, as shown in Figure 2 shown.

[0015] In the present invention, a planar electrode alternating current electroluminescent device can be simplified to three impedance units connected in series, namely the left light-emitting unit impedance, the impedance of the low-impedance bridge layer, and the right light-emitting unit impedance. Usually, the impedance of the bridge layer is ignored, and by adjusting the relative impedance of the left and right light-emitting units, the voltage is concentrated on the light-emitting unit at one end. At the same time, the higher the voltage at one end, the brighter the brightness, and the lower the voltage at the other end, the darker it is. At this time, by selecting the brighter end as the display end and the darker end as the background end, while retaining the characteristics of planar electrode alternating current electroluminescence, the problems of difficulty in integrating / patterning planar electrode alternating current electroluminescent devices and excessively high driving voltages can be solved. Further, the background unit in the two light-emitting units can not add light-emitting components, which is more conducive to improving the brightness of the display end and the overall brightness of the device.

[0016] Preferably, the electrode A and the electrode B are independently selected from at least one of electrically conductive materials such as gold, silver, copper, iron, ITO, FTO, graphene, carbon nanotubes, PEDOT, ionic conductors (hydrogels, ion gels, etc.).

[0017] It should be noted that the electrode A (background electrode) and the electrode B (display electrode) can be made of any material that can conduct electrons and ions. However, in order to reduce the loss of voltage on the electrodes, the present invention uses excellent conductive metals such as gold, silver, and copper with good conductivity. Among them, the background electrode and the display electrode can be the same or different, and preferably the same conductive material is used to simplify the preparation process. For flexible and stretchable devices, the corresponding electrodes need to be replaced with flexible and stretchable electrodes, such as silver nanowires, carbon nanotubes, silver flakes, liquid metals, graphene, ion gels, etc. Similarly, in order to reduce the loss on the electrodes, the preferably stretchable electrodes should have excellent conductivity, such as silver nanowires, liquid metals, and silver flakes.

[0018] Preferably, the spacing distance between the electrode A and the electrode B is 10 nm - 10 m.

[0019] It should be noted that as long as the electrode A and the electrode B are not electrically connected, it is okay, so the spacing between them can be very small, mainly limited by the scale that the production process can achieve. The maximum spacing distance between the electrode A and the electrode B is mainly limited by the impedance of the low-impedance bridge layer material. When the impedance of this layer is very small (for example, using materials with very small impedance such as gold, silver, and copper), the gap between the electrode A and the electrode B can be very large, dozens of meters. When the impedance of the bridge layer is relatively large (for example, using materials with slightly larger impedance such as hydrogels, ion gels, and acetone), the gap between the electrode A and the electrode B needs to be less than 1 mm to ensure the luminous intensity of the device. The main reason is that an overly long gap will cause the voltage division of the low-impedance bridge layer to be too large, resulting in too small a voltage division across the light-emitting layer, thereby reducing the luminescence of the device.

[0020] The low-impedance bridge layer only serves as a bridge connecting the light-emitting active layers at both ends, and its impedance should be much smaller than that of the light-emitting active layer. Common low-impedance bridge layer materials can be at least one of conductive materials such as gold, silver, copper, iron, ITO, FTO, graphene, carbon nanotubes, PEDOT, ionic conductors (hydrogels, ion gels, etc.), or can also be semiconductors with lower impedance and some materials with ultra-high dielectric constants, such as BaTiO3.

[0021] It should be noted that the addition of the low-impedance bridge layer can enable the planar electrode alternating current electroluminescent device to emit light. However, the thickness of the low-impedance bridge layer cannot be too thin, otherwise the impedance of the entire bridge layer will be relatively large and will no longer meet the low-impedance requirement, resulting in uneven light emission. Preferably, the thickness of the low-impedance bridge layer is 50 nm - 10 cm, and more preferably, the thickness of the low-impedance bridge layer is 0.1 μm - 10 mm.

[0022] The second aspect of the present invention provides a novel information encryption device, which uses the asymmetric enhanced planar electrode alternating current electroluminescent device of the present invention. The difference is that the low-impedance bridge layer is removed, and polar liquids such as water are used as the "key" for decryption.

[0023] It should be noted that the implementation method of this information encryption device is as follows: Planar electrodes A and B are etched on a whole electrode, where the shape of electrode A and / or B is the pattern of the information to be expressed, and the areas of electrodes A and B are different. Subsequently, the light-emitting active layer is prepared on this planar electrode by various methods such as deposition, spin coating, scraping coating, evaporation coating, printing, etc., which are not limited here. In addition, in order to protect the light-emitting active layer from being damaged by polar liquids such as water, preferably, a dielectric encapsulation layer for protection is deposited on the light-emitting active layer. It should be noted that this dielectric encapsulation layer needs to be thin enough to reduce the voltage division effect of this layer. Subsequently, an alternating current is applied to this device, and preferably, a household 220V 50Hz power supply can be used. Submerging this device into polar liquids such as water or pouring polar liquids such as water on the light-emitting active layer, the encrypted information will be displayed.

[0024] The third aspect of the present invention provides a novel large-scale integrated display device, and the array unit of this novel display uses the asymmetric enhanced planar electrode alternating current electroluminescent device of the present invention, preferably using an asymmetric structure with different areas.

[0025] It should be noted that when large-scale integrated display is adopted, multiple display electrodes: B1, B2, B3... are used. All the display electrodes are periodically arranged according to a certain rule to form pixel units, which share one or more large background electrodes A. By using currently mature driving circuits such as 2T1C and 7T2C, each display electrode terminal is switched on and off, so as to realize the display of patterns. To display different colors, every three pixel units are taken as a group. The three pixel units in a group emit red, green, and blue light respectively. Different colors are obtained by adjusting the intensities of red, green, and blue light. Each group is then periodically arranged according to a certain rule to display patterns of different colors. The arrangement mode of pixel units and the shape of pixel units are not limited here.

[0026] The fourth aspect of the present invention provides a stretchable display device, which adopts the asymmetric enhanced planar electrode alternating current electroluminescent device of the present invention, preferably with asymmetric structures of different usage areas.

[0027] It should be noted that the implementation method of the stretchable display device is as follows: all the materials in the device structure are replaced with materials having excellent stretching properties. For example, the substrate material is replaced with various polymers, such as PDMS, Ecoflex, SEBS, TPU, etc., which are not limited here. The electrodes are replaced with various stretchable electrodes, such as micro-nano wires and micro-sheets of metals such as Ag, Au, Cu, liquid metals, PEDOT:PSS, ion gels, and their composites. The low-impedance bridge layer can also be selected from low-impedance materials with stretching properties, such as various stretchable electrodes, which will not be elaborated here. It is worth noting that at least one of the electrodes and the low-impedance bridge layer of the device has high transparency.

[0028] It also should be noted that whether it is an information encryption device, large-scale integrated display, or stretchable display, as long as there is a conductive substance or polar solution on the surface of the asymmetric enhanced planar electrode alternating current electroluminescent device, it will emit light; only for different conductive substances or different polar solutions, according to the conductivity or the polarity of the solution, the light emission uniformity will be affected, which will not be specifically limited here.

[0029] The beneficial effects of the present invention are as follows: The asymmetrically enhanced planar electrode alternating current electroluminescent device of the present invention creatively expands the application of planar electroluminescence to the display field, and the device can cleverly combine display and sensing. In addition, the asymmetric structure is beneficial to concentrating the electric field on the display unit, effectively solving the problems of high driving voltage and difficulty in patterning / integration of existing planar electrode alternating current electroluminescent devices. Moreover, the asymmetrically enhanced structure has universality in structure and can be applied to all alternating current electroluminescent devices, such as AC-OLED, AC-PeLED, AC-QLED, etc. The asymmetrically enhanced planar electrode alternating current electroluminescent device of the present invention can be easily made into an information encryption device or a smart wearable display device only by adjusting the electrode pattern; the design has a simple structure, low cost, flexible and convenient operation, and wide application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic structural diagram of the asymmetrically enhanced planar electrode alternating current electroluminescent device of the present invention, and a simplified circuit schematic diagram.

[0031] Figure 2 FIG. is another schematic structural diagram of the asymmetrically enhanced planar electrode alternating current electroluminescent device of the present invention.

[0032] Figure 3 FIG. is a schematic structural diagram of the device obtained in Example 1 of the present invention.

[0033] Figure 4 FIG. is the partial voltage at both ends under different relative areas measured by applying a fixed driving voltage and frequency to the device in Example 1 of the present invention.

[0034] Figure 5 FIG. is the brightness value at both ends under different relative areas measured by applying a fixed driving voltage and frequency to the device in Example 1 of the present invention.

[0035] Figure 6 FIG. is a complex pattern composed of basic graphics designed in Example 2 of the present invention, and 1, 2, 3, 4... etc. in the figure represent the corresponding position numbers.

[0036] Figure 7 FIG. is the light emission brightness value at different positions in the asymmetrically enhanced planar electrode alternating current electroluminescent device with a complex pattern in Example 2 of the present invention.

[0037] Figure 8 FIG. is a curve showing the variation law of the light emission brightness at position 5 in the asymmetrically enhanced planar electrode alternating current electroluminescent device with a complex pattern in Example 2 of the present invention with respect to voltage and frequency.

[0038] Figure 9It is the variation law of the CIE coordinates of the light emission at position 5 with frequency in the asymmetrically enhanced planar electrode alternating current electroluminescent device with complex patterns in Embodiment 2 of the present invention.

[0039] Figure 10 They are photos of the asymmetrically enhanced planar electrode alternating current electroluminescent devices in Embodiment 3 of the present invention using tap water and hydrogel as the bridge layer respectively, each having different patterns.

[0040] Figure 11 It is the encrypted pattern designed in Embodiment 4 of the present invention.

[0041] Figure 12 They are photos of the encryption device in Embodiment 4 of the present invention before and after adding water under the application of alternating current drive.

[0042] Figure 13 It is the electroluminescence spectrogram of the encryption device in Embodiment 4 of the present invention before and after adding water under the application of alternating current drive.

[0043] Figure 14 It is the tensile property of the stretchable electrode prepared in Embodiment 5 of the present invention.

[0044] Figure 15 It is the stretchable seven-segment pattern designed in Embodiment 5 of the present invention.

[0045] Figure 16 They are photos of the measurement of the stretchable property of the device in Embodiment 5 of the present invention.

[0046] Figure 17 It is the structure of the area-asymmetrically enhanced planar electrode AC-OLED device and the chemical structure of the materials used in Embodiment 6 of the present invention.

[0047] Figure 18 It is the relationship between the luminance of part A and the input voltage in the coplanar electrode AC-OLED device with different relative areas in Embodiment 6 of the present invention.

[0048] Figure 19 It is the structure of the area-asymmetrically enhanced planar electrode AC-OLED device in Embodiment 7 of the present invention. Detailed implementation manners

[0049] Based on the principle of planar electrode alternating current electroluminescent devices, the present invention creatively proposes to design an asymmetric enhanced planar electrode alternating current electroluminescent device by using the basic principles of different impedance voltage division and different brightness due to different voltage division. Specifically, by adjusting the relative impedance of the two ends of the light-emitting active layer, the voltage is concentrated at one end of the device. At the same time, the brighter end has a higher voltage and the darker end has a lower voltage. At this time, by selecting the brighter end as the display end and the darker end as the background end, while retaining the characteristics of planar electrode alternating current electroluminescence, the problems of difficulty in integrating / patterning planar electrode alternating current electroluminescent devices and too high driving voltage can be solved.

[0050] There are various methods to specifically adjust the relative impedance of the two ends. For example, adjusting the area, thickness, dielectric constant of the light-emitting active layer at both ends, the carrier injection barrier of the light-emitting active layer, etc., which will not be limited here. Preferably, using the area strategy is the most convenient. Only need to etch the electrodes to form planar electrodes A and B with different areas, and then deposit the corresponding light-emitting active layer on the planar electrodes.

[0051] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Of course, the described embodiments are a part of the embodiments of the present invention, not all of the embodiments.

[0052] Example 1. Planar AC-TFEL device based on area asymmetric enhancement

[0053] The preparation steps of the device in this example are as follows:

[0054] 1. Provide a glass substrate with an ITO electrode on the surface, and etch the ITO electrode with a laser to form a series of planar electrodes A and B with different relative areas.

[0055] 2. Clean the electrodes successively with deionized water, ethanol and isopropanol, and finally dry the electrodes with nitrogen and treat them with Plasma for five minutes.

[0056] 3. Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex0030A component, and then stir for 10 minutes until the powder is evenly mixed with the Ecoflex 0030A component (prepolymer). Subsequently, add the Ecoflex 0030B component (crosslinking agent) to the uniformly mixed system and stir until a uniform slurry is formed.

[0057] 4. Coat the uniform slurry on a series of planar electrodes A and B with different relative areas, with a thickness of about 50 um. After coating, crosslink and cure at room temperature for 3 hours to obtain the light-emitting active layer.

[0058] 5. Finally, coat a layer of commercial silver paste on the light-emitting active layer as the low-impedance bridge layer.

[0059] The obtained device structure is as Figure 3 shown. A fixed driving voltage and frequency (250 V and 2000 Hz respectively) are applied to the device, and the voltage division and luminance at both ends under different relative areas are measured as Figure 4 and Figure 5 shown, where the ratio of the relative areas ranges from 1:1 to 1:5.

[0060] Example 2: Planar AC-TFEL device based on area-asymmetric enhancement

[0061] The preparation steps of the device in this example are as follows:

[0062] 1. Provide a glass substrate with an ITO electrode on its surface, and etch the ITO electrode with a laser to etch out a series of planar electrodes A and B with different pattern shapes. The specific patterns are shown in Figure 6 , where 1, 2, 3, 4... etc. in the figure represent the corresponding position serial numbers. In addition, the area of electrode B is smaller than that of electrode A.

[0063] 2. Clean the electrodes successively with deionized water, ethanol, and isopropanol, and finally dry them with nitrogen and treat them with Plasma for five minutes.

[0064] 3. Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex0030A component, and then stir for 10 minutes until the powders are evenly mixed with the Ecoflex 0030A component. Subsequently, add the Ecoflex 0030B component to the uniformly mixed system and stir until a uniform slurry is formed.

[0065] 4. Coat the uniform slurry onto a series of planar electrodes A and B with different relative areas, with a thickness of about 50 μm. After coating, crosslink and cure at room temperature for 3 hours to obtain a light-emitting active layer.

[0066] 5. Finally, coat a layer of commercial silver paste on the light-emitting active layer as a low-impedance bridge layer.

[0067] Measure the uniformity of light emission at different positions of the device, as well as the luminance change and color change under different voltages and frequencies, as shown in Figure 7 , 8, 9.

[0068] Example 3: Planar AC-TFEL device based on area-asymmetric enhancement (using different bridge layers)

[0069] The preparation steps of the device in this example are as follows:

[0070] 1. Provide a glass substrate with an ITO electrode on its surface, and etch the ITO electrode with a laser to etch out a series of planar electrodes A and B with different pattern shapes. Additionally, the area of electrode B is smaller than that of electrode A.

[0071] 2. Clean the electrodes successively with deionized water, ethanol, and isopropanol, and finally dry them with nitrogen and treat them with Plasma for five minutes.

[0072] 3. Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex0030A component. Then stir for 10 minutes until the powder is evenly mixed with the Ecoflex 0030A component. Subsequently, add Ecoflex 0030B component to the evenly mixed system and stir until a homogeneous slurry is formed.

[0073] 4. Knife-coat the homogeneous slurry onto a series of planar electrodes A and B with different relative areas, with a thickness of approximately 50 μm. After knife-coating, crosslink and cure at room temperature for 3 hours to obtain a light-emitting active layer.

[0074] 5. Finally, place different bridge layers, such as tap water, hydrogel, etc., on the light-emitting active layer, as Figure 10 shown.

[0075] Example 4. Information Encryption Device for Planar AC-TFEL Devices with Area Asymmetry Enhancement

[0076] The preparation steps of the device in this example are as follows:

[0077] 1. Provide a glass substrate with an ITO electrode on its surface, and etch the ITO electrode with a laser to etch out the pattern shape to be encrypted. The specific pattern design is shown in Figure 11 (The encrypted pattern is a QR code pattern. It should be noted that: since ITO has high transparency, the etched electrode cannot show this encrypted pattern). Additionally, the area of electrode B is smaller than that of electrode A.

[0078] 2. Clean the electrodes successively with deionized water, ethanol, and isopropanol, and finally dry them with nitrogen and treat them with Plasma for five minutes.

[0079] 3. Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex0030A component. Then stir for 10 minutes until the powder is evenly mixed with the Ecoflex 0030A component. Subsequently, add Ecoflex 0030B component to the evenly mixed system and stir until a homogeneous slurry is formed.

[0080] 4. Apply the uniform slurry onto the planar electrode etched with a QR code pattern, with a thickness of approximately 50 μm. After the scraping is completed, crosslink and cure it at room temperature for 3 hours to obtain the light-emitting active layer.

[0081] The resulting device is a device encrypted with a QR code pattern. If you need to decrypt the pattern, apply 220V 50Hz household alternating current to the device and pour water above the light-emitting active layer, then the QR code pattern can be displayed. The specific results are as Figure 12 and 13 shown. As can be seen from Figure 12 , when no water is added, there is no pattern; while when water is added, the QR code picture will be displayed. As can be seen from Figure 13 , it is obvious that there is a green light peak after adding water.

[0082] Example 5: Stretchable seven-segment display device based on a planar AC-TFEL device with area-asymmetric enhancement

[0083] The preparation steps of the display device in this example are as follows:

[0084] 1. Preparation of the stretchable planar electrode: Mix the prepolymer (0.2 g) and crosslinking agent (0.2 g) of Ecoflex 0030, and stir for 5 minutes first. Then add 0.6 g of methyl isobutyl ketone solvent and continue stirring for 10 minutes. Then add 1.44 g of silver microflakes to the solution containing MIBK and Ecoflex 00-30, and stir for 5 h. Scrape the obtained electrode slurry onto a polytetrafluoroethylene (PTFE) plate and perform three annealing processes (60°C for 1 hour, 110°C for 2 hours, 130°C for 2 hours) respectively. Finally, pour an appropriate amount of Ecoflex 0030 (prepolymer:crosslinking agent = 1:1, by mass) onto the electrode. After the electrode crosslinks at room temperature, peel the electrode from the PTFE plate and transfer it to a silicone rubber substrate. The stretching properties of the electrode are shown in Figure 14 . Subsequently, use a laser to etch the stretchable electrode to form a pattern capable of seven-segment display, specifically as Figure 15 shown.

[0085] 2. Preparation of Stretchable Low-Impedance Bridge Layer: Hydrogel is used as the low-impedance bridge layer. The specific preparation steps are as follows: Weigh a certain amount of DMAPS [N,N-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate inner salt], APS (ammonium persulfate), and P200 (polyethylene glycol diacrylate) and dissolve them in deionized water respectively to prepare DMAPS solution (0.25 mol / L), APS solution (0.15 mol / L), and P200 solution (0.12 mol / L). Mix 2.4 ml of DMAPS solution, 0.4 ml of APS solution, 0.12 ml of P200 solution, and 1 ml of acetone glycerol and pour them into a PTFE mold. Place the mold in a nitrogen environment and react at 60 °C for 18 hours to obtain the hydrogel. Finally, take out the hydrogel from the mold and cut it into the desired shape.

[0086] 3. Preparation of the device: Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex 0030 A component, and then stir for 10 minutes until the powder is evenly mixed with the Ecoflex 0030 A component. Subsequently, add Ecoflex 0030 B component to the evenly mixed system and stir until a homogeneous slurry is formed. Coat the homogeneous slurry onto a planar electrode etched with a seven-segment display pattern, with a thickness of about 100 μm. After coating, crosslink and cure at room temperature for 3 hours to obtain a light-emitting active layer. Finally, attach the hydrogel obtained in the previous step onto the light-emitting active layer to obtain a stretchable seven-segment display device. Measure the stretchable performance of the device. As Figure 16 shown, the area of the device can be stretched to 7 times its initial state without damage.

[0087] Example 6. Planar Electrode AC-OLED Device Based on Area Asymmetric Enhancement

[0088] The structure of the device and the chemical structures of the materials used are shown in Figure 17 . In the device structure, the aluminum layer serves as the planar electrode, ITO serves as the low-impedance bridge layer, and the rest serves as the light-emitting active layer.

[0089] The preparation steps of the device in this example are as follows:

[0090] 1. Clean the ITO glass successively with deionized water, ethanol, and isopropanol, and finally dry it with nitrogen and treat it with Plasma for five minutes.

[0091] 2. Spin-coat a layer of high-dielectric-constant dielectric material on the ITO glass substrate, and then sequentially deposit a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer (EM-R), an electron transport layer (ETL), and an electron injection layer (EIL) on the dielectric material by vacuum thermal evaporation method. Finally, evaporate planar electrodes with different areas.

[0092] In this embodiment, a series of planar electrode AC-OLED devices with a relative area ratio of 1:1 to 1:3 were fabricated, and the relationship between luminance (Part A) and input voltage was measured. The results are as Figure 18 shown. At the same input voltage, as the relative area increases, the luminance of the small area becomes brighter. It is also easy to understand that a planar AC-OLED itself can be regarded as two series-connected AC-OLEDs. When an asymmetric structure is adopted, the impedances of the two series-connected AC-OLED devices will be different. The device with a smaller area has a higher relative impedance and thus a higher voltage distribution, which means a higher luminance.

[0093] Example 7: Planar Electrode Alternating Current (AC) - QLED Device Based on Area Asymmetry Enhancement

[0094] The structure of the device and the materials used are shown in Figure 19 , where the aluminum layer serves as the planar electrode, the ITO serves as the low-impedance bridge layer, and the remaining part serves as the light-emitting active layer.

[0095] The preparation steps of the device in this embodiment are as follows:

[0096] First, ZnMgO nanoparticles were prepared with absolute ethanol (20 mg / mL) as the solvent and spin-coated uniformly on the cleaned ITO glass substrate at 3000 rpm as the electron transport layer, and baked at 110 °C for 10 minutes. The quantum dots were prepared with n-octane as the solvent (10 mg / mL) and spin-coated uniformly on the ZnMgO layer at 3000 rpm as the light-emitting layer, and baked at 100 °C for 5 minutes. After that, PVK was dissolved in 1,4-dioxane to prepare a 6 mg / ml solution, which was spin-coated on the quantum dot layer at 5000 rpm and baked at 100 °C for 10 minutes. TFB was dissolved in p-xylene to prepare an 8 mg / ml solution, which was spin-coated on the PVK layer at 3000 rpm as the hole transport layer and baked at 120 °C for 10 minutes. In a high-vacuum evaporation chamber, a MoO3 layer was thermally deposited on the TFB layer. Then, the dielectric material P(VDF-TrFE-CFE) was dissolved in DMF (100 mg / mL), spin-coated on the MoO3 layer at 1800 rpm, and baked at 100 °C for 60 minutes. Finally, aluminum electrodes A and B with different areas and a thickness of 100 nm were evaporated using a mask plate in a high-vacuum evaporation chamber.

[0097] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or modifications can be made according to the above description, and all such improvements and modifications should fall within the protection scope of the appended claims of the present invention.

Claims

1. An asymmetrically enhanced planar electrode alternating current electroluminescent device, characterized in that, Comprising: A substrate, an electrode formed on the substrate, a light-emitting active layer formed on the electrode and on the substrate not covered by the electrode, and a low-impedance bridge layer formed on the light-emitting active layer; wherein, the electrode includes electrode A and electrode B, electrode A and electrode B are spaced apart and formed on the substrate, and the area of the upper surface of electrode A and the area of the upper surface of electrode B are different; The spacing distance between electrode A and electrode B is 10 nm - 10 m; The thickness of the low-impedance bridge layer is 50 nm - 10 cm; The preparation steps of the asymmetric enhanced planar electrode alternating current electroluminescent device are as follows: Provide a glass substrate with an ITO electrode on its surface, and etch the ITO electrode with a laser to form a series of planar electrodes A and B with different relative areas; Clean the electrodes successively with deionized water, ethanol, and isopropanol, and finally dry the electrodes with nitrogen and treat them with plasma for five minutes; Weigh 1 g of commercial ZnS:Cu phosphor powder and BaTiO3 powder respectively and add them to 1 g of Ecoflex 0030A component, then stir for 10 minutes until the powders are evenly mixed with the Ecoflex 0030A component. Subsequently, add Ecoflex 0030B component to the evenly mixed system and stir until a uniform slurry is formed; Scrape the uniform slurry onto a series of planar electrodes A and B with different relative areas, with a thickness of about 50 μm. After scraping, crosslink and cure at room temperature for 3 hours to obtain the light-emitting active layer; Finally, scrape a layer of commercial silver paste on the light-emitting active layer as the low-impedance bridge layer.

2. A stretchable display device, characterized in that, The stretchable display device is the asymmetric enhanced planar electrode alternating current electroluminescent device described in Claim 1, and all materials in the planar electrode alternating current electroluminescent device are stretchable materials.

3. An information encryption device, characterized in that, Comprising: A substrate, an electrode formed on the substrate, a light-emitting active layer formed on the electrode and on the substrate not covered by the electrode; wherein, the electrode includes electrode A and electrode B, electrode A and electrode B are formed parallel and spaced apart on the substrate, the area of the upper surface of electrode A and the area of the upper surface of electrode B are different, and the upper surface of electrode A and / or the upper surface of electrode B have the required encrypted information.

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