Electroluminescent color-changing device with a double-layer structure

Abstract

The application discloses a double-layer structure electrochromic device, which realizes vertical double-layer structure electrochromic conversion by using high-field unidirectional light-emitting principle, designing multiple layers of electrodes and light-emitting layers, using screen misprint method and matching electrode control circuit. The device comprises two layers of electrochromic layers, three layers of conductive layers and a special multi-channel control driver. The three layers of conductive layers are respectively provided with independent electrode leads, and the two layers of electrochromic layers use different color powder electrochromic materials. A first transparent conductive layer is prepared on a PET substrate, a first light-emitting layer is prepared on the first transparent conductive layer, then a second transparent conductive layer is prepared on the surface of the first light-emitting layer, a second light-emitting layer is prepared on the surface of the second transparent conductive layer, and finally a third conductive layer is prepared on the surface of the second light-emitting layer. The three electrode leads are respectively connected with the special multi-channel control driver, so that the first light-emitting layer and the second light-emitting layer can respectively independently or combinedly realize light-emitting and electrochromic effect.

Description

Technical Field

[0001] This invention belongs to the field of electroluminescent display technology applications. Background Technology

[0002] Alternating current powder electroluminescent (AC) flexible surface light source devices possess advantages such as thinness, light weight, and uniform light emission, and are widely used in advertising, safety indicators, and luminous markings in automobiles, aircraft, and buildings. However, existing AC powder electroluminescent devices are primarily vertical structures, consisting of two electrode layers with a light-emitting layer and a dielectric layer sandwiched between them. The emitted color is determined by the inorganic AC powder electroluminescent material. Manufacturing a single light-emitting material results in a single device or a single light-emitting pixel, making it impossible to achieve dynamic multi-color switching within a single pixel. Furthermore, because AC powder electroluminescent material particles are mostly 7-30 micrometers in size, the area of ​​a single pixel composed of multi-color light-emitting materials is greater than 5 mm². 2 The inability to use it for color displays means that AC powder thin-film electroluminescent devices can only be used for flashing in a single color state, severely limiting their application range. Furthermore, existing three-primary-color display devices are formed by separately controlling red, blue, and green pixels on the same plane; however, the resolution of these color devices is significantly lower than that of black and white.

[0003] This invention discloses a dual-layer electroluminescent color-changing device that utilizes the high-field unidirectional light emission principle. Through a multi-layer electrode and light-emitting layer design, a staggered screen printing method, and an accompanying electrode control circuit, it achieves electroluminescent color-changing conversion in a vertical dual-layer structure. It comprises two electroluminescent layers, three conductive layers, and a dedicated multi-channel control driver. The key feature is that each of the three conductive layers has independent electrode leads, and the two electroluminescent layers use powdered electroluminescent materials of different colors. A first transparent conductive layer is prepared on a PET substrate, and a first light-emitting layer is prepared on the first transparent conductive layer. Then, a second transparent conductive layer is prepared on the surface of the first light-emitting layer, followed by a second light-emitting layer, and finally a third conductive layer is prepared on the surface of the second light-emitting layer. The three electrode leads are connected to the dedicated multi-channel control driver to achieve independent or combined light emission and color-changing effects for the first and second light-emitting layers.

[0004] This invention can be widely used in flexible thin-film displays, automotive instruments, aircraft safety indicators, thin-film lighting, electric vehicle indicators, wearable displays, and other fields. Its cost is lower than that of existing LCD and OLED devices. At the same time, the flexible thin-film color display effect of this structure compensates for the single color of existing powder electroluminescent devices, realizes the single-pixel multi-color display effect, and greatly improves the resolution. Summary of the Invention

[0005] A dual-layer electroluminescent color-changing device, comprising two electroluminescent layers and three conductive layers ( Figure 1The device, along with a dedicated multiplexer driver, is characterized by: three conductive layers, each with independent electrode leads 1-1, 1-2, and 1-3; and two electroluminescent layers using powder electroluminescent materials of different colors. A first transparent conductive layer 6 is fabricated on a flexible plastic substrate 7, followed by a first luminescent layer 5. A second transparent conductive layer 4 is then fabricated on the surface of the first luminescent layer, followed by a second luminescent layer 3, and finally a third conductive layer 2. The three electrode leads are connected to the dedicated multiplexer driver, enabling the first and second luminescent layers to emit light and change color independently or in combination. This vertically stacked electroluminescent device achieves multi-color transformation through single-pixel superposition.

[0006] The two electroluminescent layers in this invention have a vertical layered structure, with a transparent conductive layer between them. The electroluminescent layers are formed by screen printing a mixture of electroluminescent powder and binder. Different colors of electroluminescent material are used for different electroluminescent layers. The electroluminescent layers are prepared using screen printing technology. The thickness of the electroluminescent layers needs to be controlled to be similar to the particle size of the electroluminescent powder material, achieving single-layer luminescence with aligned powder particles. This dense and uniform luminescent layer is semi-transparent. The screen printing method creates a regular grid pattern, with more binder deposited along the grid's warp and weft lines, and a single layer of electroluminescent powder particles deposited within the grid. To improve the electroluminescence's voltage resistance and enhance color superposition and luminescence intensity, the two screen-printed electroluminescent layers have a staggered grid structure. The intersection of the warp and weft lines of the first luminescent layer corresponds to the center of the grid in the second luminescent layer, and vice versa. The adhesive in this invention is one of epoxy resin, acrylic acid, polyimide, and silicone, which can be temperature-cured or UV-cured. The adhesive is thoroughly mixed with the powdered electroluminescent material and printed using a 400-mesh screen. The thickness of the electroluminescent layer is less than 30 micrometers. If the electroluminescent layer is too thin, the electroluminescent material is prone to loss and breakdown. If the electroluminescent layer is too thick, it is easy to block the light-emitting effect of another layer.

[0007] To improve the repeatability and stability of the process, transparent insulating layers 8 and 9 are prepared on both sides of the second transparent conductive layer in this invention. The transparent insulating layers can improve voltage resistance without blocking light intensity, significantly improving the yield of precise batch production. The transparent insulating layer is one of polyimide, polyurethane, or acrylic, and its thickness is 0.5-1 micrometer. The transparent insulating layer can be achieved by 600-mesh screen printing or by methods such as scraping.

[0008] The three conductive layers in this invention are formed by combining a transparent conductive material with silver paste. The first transparent conductive layer is the light-emitting surface. The first and second transparent conductive layers are one of conductive polymers, silver nanowires, or nano-transparent conductive liquids. They can be prepared by coating or screen printing. Their transparency affects the superposition of luminescence intensity, and they have good conductivity. The third conductive layer is one of conductive silver paste, conductive carbon paste, or a transparent conductive material. The above three conductive layers are mutually insulated, especially at the electrode lead area, to prevent superimposed breakdown.

[0009] The powder electroluminescent material in this invention is zinc sulfide. The uniformity of the zinc sulfide particles must be strictly controlled, as particle uniformity affects the uniformity of the electroluminescent layer. The zinc sulfide matrix material is doped with copper, manganese, aluminum, and rare earth ions. The addition of rare earth ions can stably control particle uniformity and improve the stability of the emission spectrum color.

[0010] The dedicated multiplexer driver of this invention consists of electrode leads connected to three conductive layers. One end of each electrode lead is connected to a conductive layer, and the leads are staggered. The other end of each lead is connected to the dedicated multiplexer driver, which outputs a voltage of 0-150V and a frequency of 50-1000Hz. It can independently control the first and second light-emitting layers to emit light, allowing for color-changing combinations or independent emission. The input voltage of the dedicated multiplexer driver can be AC ​​or DC, ranging from 3-220V. By connecting the three conductive layers to the dedicated multiplexer driver, the driver can control the two electroluminescent layers to emit light alternately or in combination, achieving multi-color emission.

[0011] The flexible plastic substrate in this invention is made of PET, PVC, silicone rubber, polyurethane, polyimide, or fluoroplastic film, with an operating temperature greater than 80 degrees Celsius. A transparent conductive layer is sputtered or printed on the surface of the flexible plastic substrate. The flexible plastic substrate in this invention can also be used as an encapsulation and protective film.

[0012] The first transparent conductive layer in this invention is a vacuum-sputtered ITO thin film, which is sputtered onto a surface of a PET or PU substrate film. The ITO transparent conductive film has advantages such as stability, good weather resistance, and low electrical resistance. Attached Figure Description

[0013] Figure 1. Schematic diagram of a double-layer electroluminescent color-changing device In the figures of this invention: 1-1 electrode lead, 1-2 electrode lead, 1-3 electrode lead, 2 third conductive layer, 3 second light-emitting layer, 4 second transparent conductive layer, 5 first light-emitting layer, 6 first transparent conductive layer, 7 flexible plastic substrate, 8 transparent insulating layer, 9 transparent insulating layer. Specific implementation methods

[0014] A dual-layer electroluminescent color-changing device includes a specially structured electroluminescent device and its fabrication, the fabrication of electroluminescent materials for the device, and a dedicated multi-channel control driver. The structural features of the electroluminescent device are as follows: a first transparent conductive layer 6 is fabricated on a flexible plastic substrate 7; a first light-emitting layer 5 is fabricated on the first transparent conductive layer; then a second transparent conductive layer 4 is fabricated on the surface of the first light-emitting layer; next, a second light-emitting layer 3 is fabricated on the surface of the second transparent conductive layer; finally, a third conductive layer 2 is fabricated on the surface of the second light-emitting layer. The third conductive layer 2 can be transparent or opaque, and the device is then protected and sealed with the flexible plastic substrate 7. To enable stable mass production of the dual-layer electroluminescent color-changing device, transparent insulating layers 8 and 9 are fabricated on both sides of the second transparent conductive layer to improve the device's voltage withstand capability. The three conductive layers in this invention are each provided with an independent 1-1 first transparent conductive layer electrode lead, 1-2 second transparent conductive layer electrode lead, and 1-3 third conductive layer electrode lead. The three electrode leads are connected to a dedicated multi-channel control driver to independently or in combination control the first light-emitting layer and the second light-emitting layer to achieve a light-emitting color-changing effect. This vertically stacked electroluminescent device realizes multi-color transformation by superimposing single pixels.

[0015] This invention first prepares a first transparent conductive layer 6 on a flexible plastic substrate 7. The flexible plastic substrate in this invention is made of PET, PVC, silicone rubber, polyurethane, polyimide, or fluoroplastic film, and operates at a temperature greater than 80 degrees Celsius. ITO is sputtered onto the surface of the flexible plastic substrate. ITO has the advantages of stability, transparency, and low resistance. Nano-silver, conductive polymers, etc., can also be printed to prepare transparent conductive layers. The flexible plastic substrate in this invention can also be used as an encapsulation and protective film; the fluoroplastic film has good moisture resistance.

[0016] In this invention, a first light-emitting layer 5 is prepared on a first transparent conductive layer ITO by screen printing; then a second transparent conductive layer 4 is prepared by coating the surface of the first light-emitting layer; then a second light-emitting layer 3 is prepared by screen printing on the surface of the second transparent conductive layer; finally, a third conductive layer 2 is prepared on the surface of the second light-emitting layer; and finally, a flexible plastic substrate 7 is used for protection and sealing.

[0017] In order to enable the stable mass production of electroluminescent color-changing devices with a double-layer structure, the present invention prepares a transparent insulating layer 8 and an insulating layer 9 on both sides of the second transparent conductive layer to improve the voltage resistance of the device.

[0018] The three conductive layers in this invention are each provided with an independent 1-1 electrode lead, 1-2 electrode lead, and 1-3 electrode lead. The three electrode leads are connected to a dedicated multi-channel control driver to control the first light-emitting layer and the second light-emitting layer independently or in combination, thereby achieving a light-emitting color-changing effect. This vertically stacked electroluminescent device realizes multi-color transformation by superimposing single pixels.

[0019] The two electroluminescent layers in this invention have a vertical layered structure, with a transparent conductive layer disposed between them. The electroluminescent layers are formed by screen printing a mixture of electroluminescent powder and binder. Different colors of electroluminescent material are used for different electroluminescent layers. The electroluminescent layers are prepared using screen printing technology, and the thickness of the electroluminescent layers needs to be controlled to be similar to the particle size of the electroluminescent powder material. This dense and uniform luminescent layer is semi-transparent. The screen printing method creates a regular grid pattern, with more binder deposited along the warp and weft lines of the grid, and a single layer of electroluminescent powder particles deposited within the grid. To improve the voltage resistance of the electroluminescence and to achieve better color superposition and higher luminous intensity, the two screen-printed electroluminescent layers have a staggered grid structure. The intersection of the warp and weft lines of the first luminescent layer corresponds to the center of the grid in the second luminescent layer, and vice versa. To maintain precise grid positioning, a laser-guided metal mesh can be used.

[0020] The adhesive in this invention is one of epoxy resin, acrylic acid, polyimide, and silicone, which can be temperature-cured or UV-cured. The adhesive is thoroughly mixed with the powdered electroluminescent material and printed using a 400-mesh screen. The thickness of the electroluminescent layer is less than 30 micrometers. If the electroluminescent layer is too thin, the electroluminescent material is prone to loss and breakdown. If the electroluminescent layer is too thick, it is easy to block the light-emitting effect of another layer.

[0021] To improve the repeatability of the process, transparent insulating layers 8 and 9 are prepared on both sides of the second transparent conductive layer in this invention. Figure 1 The transparent insulating layer can improve voltage resistance without blocking light intensity, significantly improving the yield of precise batch production. The transparent insulating layer is one of polyimide, polyurethane, or acrylic, with a thickness of 0.5-1 micrometer. The transparent insulating layer can be achieved by 600-mesh screen printing or by methods such as scraping.

[0022] The three conductive layers in this invention are formed by combining a transparent conductive material with silver paste. The first transparent conductive layer is the light-emitting surface. The first and second transparent conductive layers are one of conductive polymers, silver nanowires, or nano-transparent conductive liquids. They can be prepared by coating or screen printing. Their transparency affects the superposition of luminescence intensity, and they have good conductivity. The third conductive layer is one of conductive silver paste, conductive carbon paste, or a transparent conductive material. The above three conductive layers are mutually insulated, especially at the electrode lead area, to prevent superimposed breakdown.

[0023] The dedicated multiplexer driver in this invention consists of electrode leads connected to three conductive layers. One end of each electrode lead is connected to a conductive layer, and the leads are staggered. The other end of each lead is connected to the dedicated multiplexer driver, which outputs an adjustable voltage of 0-150V and a frequency of 50-1000Hz. It can independently control the first and second light-emitting layers to emit light, allowing for color-changing combinations or independent emission. The input voltage of the dedicated multiplexer driver can be AC ​​or DC from 3-220V. By connecting the three conductive layers to the dedicated multiplexer driver, the driver can control the two electroluminescent layers to emit light alternately or in combination, achieving multi-color emission.

[0024] The advantages of this invention are:

[0025] This invention enables multi-color emission changes in AC powder electroluminescent devices. Existing electroluminescent planar device structures only achieve color by covering multiple printed lightbox patterns of different colors, and cannot achieve color changes.

[0026] This invention achieves color emission from a single pixel on the same plane. Existing color display devices are basically composed of three primary colors on the same plane to form a display pixel, and each pixel is formed by combining three or four independently controlled color pixels of red, blue and green. The structure of this invention is clearer.

[0027] The spherical electroluminescent material prepared by this invention has the characteristic of uniform particle size. The single-layer luminescent particle film prepared by this material is dense, uniform, and semi-transparent, and can realize the independent combination of superimposed colors to emit light.

[0028] The electroluminescent color-changing device of the present invention with a double-layer structure can be used in micro light-emitting displays, as well as in electronic wearable products, and can be combined for use in aircraft thin-film lighting and automotive button indicators.

[0029] Having described the preferred embodiments of the present invention above, it should be understood by those skilled in the art that any changes and modifications made to the present invention without departing from its spirit and scope are within the scope of the present invention.

Claims

1. A dual-layer electroluminescent color-changing device, comprising two electroluminescent layers and three conductive layers, and a dedicated multiplexer driver, characterized in that: Each of the three conductive layers has an independent electrode lead, and the two electroluminescent layers use powder electroluminescent materials of different colors. A first transparent conductive layer is prepared on a flexible plastic substrate, and a first luminescent layer is prepared on the first transparent conductive layer. Then, a second transparent conductive layer is prepared on the surface of the first luminescent layer, a second luminescent layer is prepared on the surface of the second transparent conductive layer, and finally a third conductive layer is prepared on the surface of the second luminescent layer. The three electrode leads are connected to a dedicated multiplexer driver to achieve the color-changing effect of independent or combined emission of the first and second luminescent layers.

2. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: The two electroluminescent layers have a vertical layered structure, with a transparent conductive layer between them. The electroluminescent layers are formed by screen printing electroluminescent powder material. The two screen-printed electroluminescent layers have a grid misalignment structure, and the thickness of the electroluminescent layers is less than 30 micrometers, forming a single-layer luminescent particle luminescent layer.

3. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: A transparent insulating layer is prepared on both sides of the second transparent conductive layer. The transparent insulating layer is one of polyimide, polyurethane, or acrylic acid, and the thickness of the transparent insulating layer is 0.5-1 micrometer.

4. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: The three conductive layers are formed by combining transparent conductive materials with silver paste. The first and second transparent conductive layers are one of conductive polymers, silver nanowires, and transparent conductive nano liquids, while the third conductive layer is one of conductive silver paste, conductive carbon paste, and transparent conductive materials.

5. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: The dedicated multiplexer driver has electrode leads that are connected to the three conductive layers respectively. The dedicated multiplexer driver outputs an adjustable voltage of 0-150V and a frequency of 50-1000Hz, and can control the first and second light-emitting layers to emit light independently.

6. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: Electrode leads connect the three conductive layers to a dedicated multiplexer driver, which can control the two electroluminescent layers to emit light alternately or in combination, achieving multi-color light emission.

7. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: The flexible plastic substrate is made of PET, PVC, silicone rubber, polyurethane, polyimide, or fluoroplastic film, with an operating temperature greater than 80 degrees Celsius. A transparent conductive layer is sputtered or printed on the surface of the flexible plastic substrate.

8. The electroluminescent color-changing device with a double-layer structure according to claim 1, characterized in that: The first transparent conductive layer is a vacuum-sputtered ITO thin film, which is sputtered onto the surface of a PET or PU substrate film.

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