Mixed ink for displaying visual persistence image and application of mixed ink

Abstract

The invention discloses mixed ink for displaying a vision persistence image, and belongs to the field of storage device technologies and vision persistence. The mixed ink is formed by taking graphene nanosheets and tungsten disulfide nanoparticles as active components and water as a solvent, the mixed ink can be used for printing and preparing the flexible photoelectric storage device, and the obtained flexible photoelectric storage device has the characteristic of medium and long storage time, and can be used for preparing the flexible photoelectric storage device by extracting information at different moments. According to the method, the corresponding process is obtained and displayed as the image in sequence, so that the image of the persistence of vision process can be extracted, and the image is completely displayed, and therefore, a simple, convenient, feasible and reliable technical means is provided for realizing persistence of vision image display by using the photoelectric memory.

Description

Technical Field

[0001] The present invention belongs to the field of storage device technology and persistence of vision, and specifically relates to a mixed ink for persistence of vision image display, and a flexible photoelectric storage device printed with the mixed ink. The photoelectric storage device has the characteristics of medium- and long-term storage time, and can extract information at different moments to obtain corresponding processes and display them as images in sequence, so as to simulate the human persistence of vision phenomenon and realize the persistence of vision image display. Background Art

[0002] In recent years, the rapid development of neuromorphic computing and machine vision technologies has attracted widespread attention. They aim to simulate the neural network and visual system of the human brain and achieve efficient information processing and intelligent decision-making through complex signal processing and advanced algorithms. Optoelectronic memory is an important component of these systems, which uses optical signals for data storage and processing. Optoelectronic memory has attracted much attention due to its unique ability to accumulate and release photogenerated carriers under electrical stress and light irradiation. More importantly, optoelectronic memory provides a huge opportunity to integrate multiple functions such as optical sensing, data storage and processing into a single device with high speed, large capacity and low power consumption.

[0003] Persistence of vision image display is an important computer vision technology, which can be used in application scenarios such as target tracking and virtual reality. Existing methods for persistence of vision image display mainly focus on using electronic display devices, such as LCD, OLED, etc., to display image information on the screen. This method requires continuous power supply to maintain image display, and has disadvantages such as high energy consumption and high cost. Using optoelectronic storage for image recognition can store image information on optical media, and the image display can be maintained without continuous power supply. However, most of the existing optoelectronic storage technologies are concentrated on other recognition applications, such as text recognition, barcode recognition, etc., and there has been no research on persistence of vision image display. Summary of the invention

[0004] In order to solve the problem of how to use an optoelectronic memory device to display a persistent image, the present invention provides a mixed ink for displaying a persistent image and an application of the mixed ink in printing a flexible optoelectronic memory device.

[0005] To achieve the above object, the present invention adopts the following technical solution: One of the purposes of the present invention is to protect a mixed ink for displaying visual persistence images, which is composed of graphene nanosheets and tungsten disulfide nanoparticles as active components and water as a solvent.

[0006] Furthermore, the concentrations of graphene nanosheets and tungsten disulfide nanoparticles in the mixed ink are both 0.5 mg / mL.

[0007] Furthermore, the graphene nanosheet is wrinkled, and its lateral size is 2-5 μm.

[0008] Furthermore, the tungsten disulfide nanoparticles are irregular particles with a particle size of 100-200 nm.

[0009] Furthermore, the method for preparing the mixed ink comprises the following steps: 1) Add tungsten disulfide powder into water, stir thoroughly and then perform ultrasonic treatment to obtain a tungsten disulfide nanoparticle dispersion; 2) adding graphene nanosheets into water, stirring thoroughly and then performing ultrasonic treatment to obtain a graphene nanosheet dispersion; 3) The obtained tungsten disulfide nanoparticle dispersion liquid and graphene nanosheet dispersion liquid are mixed, fully stirred and subjected to ultrasonic treatment to obtain the mixed ink.

[0010] Furthermore, the power of the ultrasonic treatment is 250 W and the time is 2 h.

[0011] The second purpose of the present invention is to protect a flexible photoelectric memory prepared by printing with the mixed ink. The construction mechanism of the flexible photoelectric memory is that the mixed ink is a mixture of graphene nanosheets and tungsten disulfide nanoparticles, wherein the agglomerated morphology of the graphene nanosheets is a large-area wrinkled shape, so the tungsten disulfide nanoparticles can be well fixed on the wrinkled graphene nanosheets under stirring conditions without stratification, and because the edge volume fraction of the tungsten disulfide nanoparticles is large, the edges can have a higher defect density, so when the laser is irradiated, the defects at the edges of the tungsten disulfide nanoparticles will capture photogenerated carriers and store electrons / holes generated by light stimulation, so that the current will not return to the initial state after the light stimulation is removed, and a part of the photocurrent still exists, thereby achieving the effect of photoelectric storage.

[0012] Furthermore, the method for preparing a flexible optoelectronic memory by printing with the mixed ink comprises the following steps: Step S1: using a flexible material as a substrate; Step S2: using a microelectronic printer, printing a silver-based particle-free conductive ink on a flexible substrate to prepare a silver interdigital electrode, and then heating and curing the silver interdigital electrode; Step S3: dripping the mixed ink on the active area in the middle of the silver interdigital electrode, and drying it at room temperature to form a mixed ink active area coating, thereby obtaining the flexible optoelectronic memory.

[0013] Furthermore, in step S1, the flexible material is selected from one of polyimide, polyethylene terephthalate, and polyethylene naphthalate, and has a thickness of 60 μm.

[0014] Furthermore, the size of the silver interdigital electrode in step S2 is 0.2-0.5 mm×1-1.5 mm, and the thickness is 50-200 nm.

[0015] Furthermore, the temperature of the heating and curing in step S2 is 150°C to 180°C, and the time is 30 min to 50 min.

[0016] Furthermore, the thickness of the mixed ink active area coating formed in step S3 is 0.1-0.5 mm.

[0017] The third purpose of the present invention is to protect the application of the flexible optoelectronic memory prepared by mixed ink printing in the display of visual persistence images. The application mechanism is to apply laser stimulation to the pixel array system constructed by the flexible optoelectronic memory at different times, and compare the average current value of a certain stage with that of the previous stage, and output a signal 1 or a signal 0 according to the change of the current average value, so as to obtain the corresponding process by extracting information at different times and displaying it as an image in sequence, so as to complete the display of visual persistence images.

[0018] Furthermore, the application method specifically comprises the following steps: a) expanding the flexible optoelectronic memory prepared by printing with the mixed ink into a pixel array system, wherein each pixel corresponds to a flexible optoelectronic memory; b) using a laser to send optical signals to the array system at different time stages, so that the conductivity of the pixel array changes under the laser stimulation and transitions to a conductive state; c) Extract the current value after each stage change and calculate the average value of each stage. If the average current value of a certain stage exceeds a fixed value compared with the previous stage, the system outputs a 1 signal; otherwise, the output signal is 0; d) Extract the output current at the final moment, calculate the average value of the final output current, compare it with the average value of the input current, obtain the output signal, and display the output signal as an image to form a complete image.

[0019] Furthermore, the laser wavelength used in step b) is 405 nm and the power is 2.8 mW; Furthermore, the fixed value set in step c) may be 2 μA.

[0020] In the suspension prepared by using WS2 powder in the present invention, the tungsten disulfide material is irregular particles with obvious agglomeration phenomenon. After compounding, this material will provide more defect sites for capturing photogenerated carriers to achieve the purpose of storing photocurrent (after removing the light stimulus, the current will not return to the initial state, but will be stored for a period of time), so it can be used as a photoelectric storage device.

[0021] The significant advantages of the present invention are: (1) The present invention uses graphene nanosheets and tungsten disulfide nanoparticles as active components and water as solvent. The mixed ink can be prepared by simple ultrasonic dispersion at room temperature and pressure. The equipment is simple, the raw materials are widely available, the cost is low, and it can be prepared in large quantities. In the process, tungsten disulfide powder is directly dispersed in water, and no long-term ultrasonic peeling is required, which simplifies the difficulty of ink preparation.

[0022] (2) The present invention can print and prepare flexible optoelectronic memory devices using the obtained mixed ink, which provides a new method for preparing printed optoelectronic memory devices and greatly simplifies the preparation process of the device structure. (3) The flexible photoelectric storage device prepared by the present invention has the characteristics of medium- and long-term storage time. By extracting information at different moments, the corresponding process can be obtained and displayed as images in sequence, thereby extracting the image of the visual persistence process and displaying the image completely. Therefore, the present invention provides a simple, easy and reliable technical means for realizing visual persistence image display using photoelectric storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the flexible optoelectronic memory prepared in Example 2.

[0024] Figure 2 It is a comparison diagram of the light response curves of the flexible optoelectronic storage prepared in Example 2 and the comparative example.

[0025] Figure 3 This is a schematic diagram of a 4×4 optoelectronic memory pixel array system prepared in Example 3.

[0026] Figure 4 This is a schematic diagram of the process of writing the letters "FZU" in Example 3.

[0027] Figure 5 This is a schematic diagram of the information extraction process of Example 3.

[0028] Figure 6 This is a diagram of the response of the pixel array system to the writing process of the letter "F" and the information extraction process in Example 3. DETAILED DESCRIPTION

[0029] A mixed ink for displaying a persistent visual image, the preparation method of which comprises the following steps: 1) Add tungsten disulfide powder into water, stir thoroughly and then ultrasonicate at 250 W for 2 h to obtain a tungsten disulfide nanoparticle dispersion; 2) adding graphene nanosheets into water, stirring thoroughly and then ultrasonically treating at 250 W for 2 h to obtain a graphene nanosheet dispersion; 2) The obtained tungsten disulfide nanoparticle dispersion and graphene nanosheet dispersion were mixed and fully stirred, and then ultrasonically treated at 250 W for 2 h to obtain a mixed ink with a concentration of 0.5 mg / mL for both graphene nanosheets and tungsten disulfide nanoparticles.

[0030] The graphene nanosheets are wrinkled, and their lateral dimensions are 2-5 μm. The tungsten disulfide nanoparticles are irregular particles, and their particle size is 100-200 nm.

[0031] The mixed ink can be used to print and prepare a flexible optoelectronic memory, and the preparation method thereof comprises the following steps: Step S1: using a flexible material as a substrate; Step S2: using a microelectronic printer, printing a silver-based particle-free conductive ink on a flexible substrate to prepare a silver interdigital electrode with a size of 0.2-0.5 mm×1-1.5 mm and a thickness of 50-200 nm, and then heating the silver interdigital electrode at 150° C.-180° C. for 30 min-50 min to ensure that the electrode is completely cured; Step S3: dripping the mixed ink on the active area in the middle of the silver interdigital electrode, and drying it at room temperature to form a mixed ink active area coating with a thickness of 0.1-0.5 mm, thereby obtaining the flexible optoelectronic memory.

[0032] Wherein, the flexible material in step S1 is selected from one of polyimide, polyethylene terephthalate and polyethylene naphthalate, and has a thickness of 60 μm.

[0033] In a possible implementation, the flexible optoelectronic memory prepared by the mixed ink printing is expanded into a 4×4 pixel array system, which is composed of 16 independent flexible optoelectronic memories, and each pixel corresponds to a flexible optoelectronic memory. When in use, a series of optical input signals are sent to the system at different time stages. Under laser stimulation, the conductivity of each device (pixel) changes and transitions to a conductive state; the current value after each stage is extracted, and the average value of each stage is calculated. If the average current value of a certain stage exceeds the previous stage by more than 2 μA, the system outputs a 1 signal, otherwise, the output signal is 0; the current signal output at the final moment is extracted and displayed as an image, so that a complete image can be formed.

[0034] The technical solutions in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1 Preparation of mixed ink 1) Add 5 mg of tungsten disulfide powder to 5 mL of deionized water, stir thoroughly for 30 min, and then place in a water bath ultrasonic device for 5 h to obtain a tungsten disulfide nanoparticle dispersion; 2) Add 5 mg of graphene nanosheets to 5 mL of deionized water, stir thoroughly for 30 min, and then place in a water bath ultrasonic device for ultrasonic dispersion for 5 h to obtain a graphene nanosheet dispersion; 3) The obtained tungsten disulfide nanoparticle dispersion and graphene nanosheet dispersion were mixed and stirred for 30 minutes, and then placed in a water bath ultrasonic device for ultrasonic dispersion for 5 hours to obtain a graphene nanosheet / tungsten disulfide nanoparticle mixed ink.

[0036] Example 2 Printing of Flexible Optoelectronic Memory Devices 1) A polyethylene terephthalate (PET) film with a thickness of 60 μm is used as a flexible substrate, which can be bent arbitrarily within a certain limit; 2) Using a microelectronic printer, a pair of silver interdigital electrodes with a size of 0.2 mm × 1 mm and a thickness of 200 nm were printed on a flexible substrate using a silver-based particle-free conductive ink. The electrodes were then placed on a heating table at 150 °C for 30 min to ensure that the electrodes were fully cured. 3) The graphene nanosheet / tungsten disulfide nanoparticle mixed ink prepared in Example 1 is drop-coated on the active area in the middle of the interdigitated electrode and dried at room temperature to form a mixed ink active area coating with a coating thickness of 0.1 to 0.5 mm, thereby obtaining a flexible optoelectronic memory prepared by mixed ink printing.

[0037] The structure of the obtained flexible optoelectronic memory is as follows Figure 1 shown.

[0038] Comparative Example The tungsten disulfide powder used in step 1) of Example 1 was replaced with tungsten disulfide nanosheets prepared by liquid phase exfoliation, and the other steps were carried out as in Example 1 to prepare a graphene nanosheet / tungsten disulfide nanosheet mixed ink, which was then used to print and prepare a flexible optoelectronic memory device according to the method described in Example 2.

[0039] A voltage of 1 V was applied to the photoelectric memory prepared by printing in Example 2 and the comparative example, and a laser with a wavelength of 405 nm and a power of 2.8 mW was used for excitation for a duration of 10 s. The results are shown in FIG. Figure 2 . As can be seen from the figure, the photocurrent in the device printed with the graphene nanosheet / tungsten disulfide nanoparticle mixed ink has a clear upward trend, and a high photocurrent can still be maintained after the light stimulus is removed. Liquid phase exfoliation obtains a thin layer of two-dimensional tungsten disulfide nanosheets with a smaller size, which has a small defect density. The devices prepared by composite printing with other material dispersions can be regarded as small heterogeneous structures. After the light stimulus is removed, the current will return to the initial state faster. Therefore, the photocurrent of the device printed with the graphene nanosheet / tungsten disulfide nanosheet mixed ink rises slowly, and the storage effect of the photocurrent is poor. This proves that devices printed based on graphene nanosheet / tungsten disulfide nanoparticle mixed ink exhibit stronger storage capacity.

[0040] Embodiment 3: Displaying a Persistent Vision Image Using an Optical Storage Device In this embodiment, a 4×4 photoelectric memory pixel array system is prepared. Through the information extraction process, a human visual persistence image display test is performed on the process of writing the letters "FZU". The specific operations are as follows: 1) The flexible optoelectronic memory prepared in Example 2 is expanded into a 4×4 pixel array system (i.e., the pixel array system is composed of 16 independent flexible optoelectronic memories), each pixel corresponds to a flexible optoelectronic memory, and the array system is as follows Figure 3 shown.

[0041] 2) During the process of writing the letters "FZU", five consecutive moments are recorded for each letter, each moment lasting 35 seconds, of which the first 10 seconds are the laser irradiation stage and the last 25 seconds are the reading stage; the laser wavelength is 405 nm and the power is 2.8 mW; the process is as follows Figure 4 As shown, the gray pixels represent writing, indicating that the laser is irradiating at this moment, and the white pixels represent no writing, indicating that the laser is not irradiating at this moment. In the five consecutive moments, the writing process represented by each moment is consistent with the stroke order of the letters "FZU".

[0042] 3) At the final moment, the output current is extracted and the average value of the final output current is calculated and compared with the average value of the input current. If the output average current value exceeds the input value by more than 2 μA, the system outputs a 1 signal; otherwise, the output signal is 0. The information extraction process is as follows: Figure 5 As shown (in this process, multiple different signals can be output by applying multiple different lasers; 4) Figure 6The response and information extraction of the constructed pixel array system to the writing process of the letter "F" are shown in Figure 1. It shows 10 representative pixels (from bottom to top: P1, P2, P3, P4, P5, P9, P 10 , P 11 , P 12 and P 13 ) is consistent with the stroke sequence of the letter "F". The output signals at five consecutive moments can completely write the image of the letter "F". The complete image of the letter "F" can be extracted by simply extracting the output current and following the information extraction process.

[0043] As can be seen from the above, each time writing occurs, a photoelectric signal is generated in the corresponding pixel area, so that the defect state of the device in this area is occupied by photogenerated electrons. As the writing process progresses, the defect states at different pixel positions are gradually "lit up". At all consecutive moments, each pixel will output a corresponding photoelectric signal, which will be captured and stored by the defect state in the device. Based on these medium- and long-term stored dynamic information, the complete letter image can be reconstructed in the end.

[0044] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A mixed ink for displaying a persistent image, characterized in that: The mixed ink is composed of graphene nanosheets and tungsten disulfide nanoparticles as active components and water as solvent; The concentrations of graphene nanosheets and tungsten disulfide nanoparticles were both 0.5 mg / mL.

2. The mixed ink according to claim 1, characterized in that: The graphene nanosheet is wrinkled, and its lateral size is 2-5 μm.

3. The mixed ink according to claim 1, characterized in that: The tungsten disulfide nanoparticles are irregular particles with a particle size of 100-200 nm.

4. The mixed ink according to claim 1, characterized in that: The preparation method comprises the following steps: 1) Add tungsten disulfide powder into water, stir thoroughly and then perform ultrasonic treatment to obtain a tungsten disulfide nanoparticle dispersion; 2) adding graphene nanosheets into water, stirring thoroughly and then performing ultrasonic treatment to obtain a graphene nanosheet dispersion; 3) The obtained tungsten disulfide nanoparticle dispersion liquid and graphene nanosheet dispersion liquid are mixed, fully stirred and subjected to ultrasonic treatment to obtain the mixed ink.

5. A flexible photoelectric memory prepared by printing with the mixed ink according to claim 1, characterized in that: The preparation method comprises the following steps: Step S1: using a flexible material as a substrate; Step S2: using a microelectronic printer, printing a silver-based particle-free conductive ink on a flexible substrate to prepare a silver interdigital electrode, and then heating and curing the silver interdigital electrode; Step S3: dripping the mixed ink on the active area in the middle of the silver interdigital electrode, and drying it at room temperature to form a mixed ink active area coating, thereby obtaining the flexible optoelectronic memory.

6. The flexible optoelectronic memory according to claim 5, characterized in that: In step S1, the flexible material is selected from one of polyimide, polyethylene terephthalate, and polyethylene naphthalate, and has a thickness of 60 μm.

7. The flexible optoelectronic memory according to claim 5, characterized in that: The size of the silver interdigital electrode in step S2 is 0.2-0.5 mm×1-1.5 mm, and the thickness is 50-200 nm.

8. The flexible optoelectronic memory according to claim 5, characterized in that: The temperature of the heating and curing in step S2 is 150°C to 180°C, and the time is 30 min to 50 min.

9. The flexible optoelectronic memory according to claim 5, characterized in that: The thickness of the mixed ink active area coating formed in step S3 is 0.1-0.5 mm.

10. Use of the flexible optoelectronic memory as claimed in claim 5 in visual persistence image display.

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