Preparation and application of flexible photoelectric detector based on copper ammonia complex and zinc oxide nanowire stacking

Abstract

The invention relates to a design method of a flexible photoelectric detector based on (Cu (NH3)) (CN) and ZnO nanowire stacking, and the method specifically comprises the steps: stacking (Cu (NH3)) (CN) on a ZnO NWs structure in the radial direction, greatly reducing the dark current of ZnO NWs through the coupling of a piezoelectric effect and a charge trapping effect, improving the responsivity, and achieving the adjustable threshold voltage. According to the excellent photoelectric property, a simple physical encryption protocol is provided, and an ultraviolet communication system and an ultraviolet display system are constructed. The design method of the ZnO nanowire photoelectric detector stacked by (Cu (NH3)) (CN) has excellent application expansibility and can be applied to the fields of encrypted optical communication, flexible integrated systems and the like. The photoelectric detector is small in size and meets the requirements of flexible electronics, which indicates that the photoelectric detector based on the design does not cause too complex wiring when being attached to clothes or a body, can realize real-time electric conversion communication, and has wide development potential in the fields of optical communication and ultraviolet display.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric detection and optical wireless communication, and specifically relates to the preparation and application of a flexible photoelectric detector based on stacking of (Cu(NH3))(CN) and ZnO nanowires. Background Art

[0002] As an important supplement to communications in radio-silent scenarios, the application of optical wireless communications in intelligent transportation, 6G technology, and battlefield communications has attracted widespread attention. Among them, ultraviolet light communication has become an ideal choice for short-range communications due to its advantages such as non-line-of-sight communication and extremely low background noise, and is also widely used in encryption of short-range communications. Photodetectors, as important components of optical communication systems, are extremely important for high-fidelity information transmission. In recent years, with the development of flexible electronic technology, flexible photodetectors have shown broad prospects in optoelectronic applications with their unique flexibility and bendability, as well as excellent optoelectronic properties, providing new possibilities for improving the performance and application scenarios of optical communication systems.

[0003] However, there are still some urgent problems to be solved in flexible photodetectors, and there are common problems with dark current and photoelectric performance regulation. Large dark current reduces the signal-to-noise ratio, increases energy loss, and greatly affects the detection accuracy and service life of flexible photodetectors. Therefore, how to reduce dark current has become an important problem in research. In terms of photoelectric performance regulation, flexible photodetectors face many challenges in material and structural design. The response speed and threshold voltage of flexible photodetectors are two key indicators of photoelectric performance. How to improve the response speed and expand the threshold voltage has become a hot topic in current research. Therefore, the preparation of flexible photodetectors with good electrical and optical properties has far-reaching significance for optical communication applications. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a design method of a flexible photodetector based on (Cu(NH3))(CN) and ZnO nanowire stacking, and applies it to the fields of optical communication and ultraviolet imaging.

[0005] In order to achieve the above purpose, the technical solution of the present invention is:

[0006] The preparation method of a flexible photodetector stacked with copper ammonia complex (Cu(NH3))(CN)) and zinc oxide (ZnO) nanowires comprises the following specific steps:

[0007] 1) Use PET as the substrate, wash it with deionized water, dry it in an oxygen-free environment at 40 degrees Celsius for 12 hours, then oxidize it in the air to form a silicon dioxide layer, connect the needle to the positive electrode of a high-voltage power supply, and stick a graphene tape on it as an electrode;

[0008] 2) preparing particle-free zinc ink and particle-free copper ink, storing the ink in a syringe, delivering the ink to a needle through a precision injection pump, preparing conductive fibers using electrospinning direct writing technology, applying an electric field force generated by a high voltage between the needle and the substrate as a driving force to form a stable jet, and preparing (CH3COO)2Zn / PEO precursor fibers on a PET substrate under the traction of the moving platform;

[0009] 3) After the (CH3COO)2Zn / PEO precursor fiber is prepared, the direction of the substrate is adjusted so that the (CH3COO)2Zn / PEO precursor fiber and the moving direction of the moving platform are 90 degrees, and then the (CH3COO)2Cu / PEO precursor fiber is prepared on the same substrate so that the (CH3COO)2Zn / PEO precursor fiber and the (CH3COO)2Cu / PEO precursor fiber are arranged in a cross shape;

[0010] 4) After sintering at 50° C., ZnO nanowires and copper ammonia complex ((Cu(NH3))(CN)) nanowires are formed, and finally encapsulated with polyimide tape.

[0011] A more preferred solution is that the PET has a thickness of 0.3 mm and a size of 3-5 cm x 3-5 cm.

[0012] A more preferred solution is that the graphene conductive tape has a thickness of 0.25 mm and a size of 3 to 5 cm x 1 to 2 cm.

[0013] Application of the flexible photodetector prepared by the above preparation method, the flexible photodetector is used in the fields of optical communication and ultraviolet imaging

[0014] The above technical solution has the following beneficial effects:

[0015] 1) The method of stacking (Cu(NH3))(CN) radially on ZnONWs used in the present invention makes full use of the coupling of piezoelectric effect and charge trapping effect, greatly reduces the dark current of ZnONWs, and greatly improves the responsivity, with a responsivity of 13.3A / W, and the rise time and fall time are 11ms and 9ms respectively.

[0016] 2) Select a device with a threshold voltage of 20 V (the number of stacked layers is 25), and all biases are set to a fixed value of 10 V. Under a bias of 10 V, the current of the ZnO nanowire gradually decreases from 2.89e-4 to 1.12e-7 as the stacking increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the photodetector structure.

[0018] Figure 2 Schematic diagram of the preparation process of the photodetector.

[0019] Figure 3 This is the current response diagram of the photodetector with different numbers of layers.

[0020] Figure 4 This is the current intensity response diagram of the photodetector with 25 stacked layers.

[0021] Figure 5 This is a graph showing how the switching current of the photodetector changes with the number of stacked layers.

[0022] Figure 6 , 7 8 is a diagram showing the application of the photodetector in ultraviolet communication.

[0023] Fig. 9 , 10 , 11 are diagrams showing the application of the photodetector in ultraviolet display. DETAILED DESCRIPTION

[0024] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0025] Embodiment 1:

[0026] 1) Using PET with a thickness of 1 mm as the substrate, a silicon dioxide layer was oxidized in the air, and a needle with an outer diameter of 0.23 mm and an inner diameter of 0.08 mm was connected to the positive electrode of a high voltage power supply (DW-SA403-1ACE5, Tianjin Dongwen High Voltage Power Supply Co., Ltd., China), and a graphene tape was attached as an electrode.

[0027] 2) Prepare a particle-free zinc ink with 5% zinc acetate by mass, 12% PEO by mass, a volume ratio of water to anhydrous ethanol of 1:2, and a molar ratio of zinc acetate to isopropanolamine of 1:5. First, take 0.25g zinc acetate dihydrate and dissolve it in 1.54g deionized water. After it is completely dissolved, add 2.43g ethanol, 0.43g isopropanolamine, and finally add 0.6g PEO. After sealing, put in magnetic particles and stir at 25°C for 48 hours.

[0028] 3) The ink is stored in a 1 mL syringe (Jiangsu Zhiyu Medical Instrument Co., Ltd.) and delivered to the needle by a precision syringe pump (Pump11Pico Plus Elite, Harvard Apparatus). PET is driven by a motion platform (POT-G-MOT-F09-06, Jiangxi Liansheng Precision Optical Platform) to deposit nanofibers with a certain structural morphology according to a pre-designed trajectory.

[0029] 4) Conductive fibers were prepared using electrospinning direct writing technology. The electric field force generated by applying a high voltage between the needle and the substrate was used as a driving force to form a stable jet. Under the moving traction of the platform, the jet was first used to prepare the (CH3COO)2Zn / PEO precursor fiber on the PET substrate.

[0030] 5) After the (CH3COO)2Zn / PEO precursor fiber is prepared, the substrate direction is adjusted so that the (CH3COO)2Zn / PEO precursor fiber is at 90° to the moving direction of the moving platform, and then the (CH3COO)2Cu / PEO precursor fiber is prepared on the same substrate.

[0031] 6) After sintering at 50°C, ZnO nanowires and (Cu(NH3))(CN) nanowires are formed. Finally, polyimide tape is used for packaging.

[0032] like Figure 1 As shown, on a PET substrate, (Cu(NH3))(CN) was artificially stacked radially on ZnO NWs using electrospinning technology, making full use of the coupling of piezoelectric effect and charge trapping effect to significantly reduce the dark current of ZnO NWs, improve the responsivity, and have an adjustable threshold voltage.

[0033] like Figure 3 As shown, the performance of the flexible photodetector based on the stacking of (Cu(NH3))(CN) and ZnO nanowires is improved, and the dark current is greatly reduced as the number of stacking layers increases.

[0034] like Figure 4 As shown in the figure, the performance of the flexible photodetector based on the stacking of (Cu(NH3))(CN) and ZnO nanowires is improved. When 25 layers of (Cu(NH3))(CN) are stacked, the responsiveness of the flexible photodetector is significantly improved, and it has good switching characteristics.

[0035] like Figure 5 As shown in the figure, the switching current of the photodetector changes with the number of stacking layers. It can be seen that as the number of stacking layers increases, the proportion of dark current decreases significantly.

[0036] Based on its excellent optoelectronic properties, a simple physical encryption protocol can be set up. The sender and the receiver use the same mask as the key. The sender extracts the grid information of the mask and modulates the optical signal. The receiver receives and shields the optical signal by moving the mask. Specifically, the sender and the receiver agree on a truth table (including correct signals, invalid signals, and confusing signals) in advance. The sender extracts the grid information on the mask into transparent grid points and opaque grid points. The sender sends the correct optical signal at the transparent grid points and transmits random confusing signals at the opaque grid points. The receiver receives the correct optical signal by synchronously moving the mask and shields the confusing signal. Finally, the information is decoded and output according to the agreed truth table.

[0037] As shown in the figure, the UV communication system includes the transmitter, optical communication, analog front end, ADC analog-to-digital conversion and display. First, the sender and receiver define the encoding of "A" to "Z" from 00000 to 11001, the space is encoded as 11010, and the others are obfuscated codes. The communication truth table is as follows Figure 7 . Specifically, the sender and the receiver agree on a truth table (including correct signals, invalid signals, and confusing signals) in advance. The sender extracts the grid information on the mask into transparent grids and opaque grids. The sender sends the correct optical signal at the transparent grids and transmits random confusing signals at the opaque grids. The receiver receives the correct optical signal by synchronously moving the mask and shielding the confusing signal. Finally, the information is decoded and output according to the agreed truth table. The sender inputs the sending string into the host computer and sends the binary code by modulating the switch of the ultraviolet laser. After a certain distance of transmission, it is received by the ZnO@(Cu(NH3))(CN) photodetector. The analog front end mainly includes an amplification circuit and a filtering circuit, which are used to receive the optical signal and convert it into an electrical signal for preliminary processing. This example takes the transmission of "XMU" as an example. The waveform of the receiving host computer is as follows Figure 8 ,It can be seen that the machine can correctly identify the ,information conveyed by the sender, and because the higher switching ratio allows a ,certain error, the high response speed allows a high transmission ,rate.

[0038] This design method can be used as an important supplement in radio shielding scenarios and has great application potential in the field of ultraviolet communications.

[0039] Based on the excellent photoelectric properties of ZnO@(Cu(NH3))(CN), a UV imaging system was constructed. Fig. 9 As shown, the wavelength used is 254nm and the power is 5.6mW / cm 2The hollow template is irradiated with an ultraviolet laser, and ZnO@(Cu(NH3))(CN) is used to receive the photoelectric signal. The current data is collected by the movement of the template using an IV analyzer. After being processed and analyzed by a computer, it is colored according to its current intensity to obtain a clear image. Fig.10 Results are displayed for the letters "XMU". Fig.11 This is the display effect of different stacking layers. It can be seen that when the stacking layer number is 25, the word "XMU" can be clearly displayed.

[0040] Although the above embodiments have been described, once those skilled in the art know the basic creative concepts, they can make additional changes and modifications to these embodiments. Therefore, the above description is only an embodiment of the present invention and does not limit the patent protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a flexible photodetector based on a stack of copper ammonia complex and zinc oxide nanowires, characterized in that: The specific steps are as follows: 1) Use PET as the substrate, wash it with deionized water, dry it in an oxygen-free environment at 40 degrees Celsius for 12 hours, then oxidize it in the air to form a silicon dioxide layer, connect the needle to the positive electrode of a high-voltage power supply, and stick a graphene tape on it as an electrode; 2) preparing particle-free zinc ink and particle-free copper ink, storing the ink in a syringe, delivering the ink to a needle through a precision injection pump, preparing conductive fibers using electrospinning direct writing technology, applying an electric field force generated by a high voltage between the needle and the substrate as a driving force to form a stable jet, and preparing (CH3COO)2Zn / PEO precursor fibers on a PET substrate under the traction of the moving platform; 3) After the (CH3COO)2Zn / PEO precursor fiber is prepared, the direction of the substrate is adjusted so that the (CH3COO)2Zn / PEO precursor fiber and the moving direction of the moving platform are 90 degrees, and then the (CH3COO)2Cu / PEO precursor fiber is prepared on the same substrate so that the (CH3COO)2Zn / PEO precursor fiber and the (CH3COO)2Cu / PEO precursor fiber are arranged in a cross shape; 4) After sintering at 50° C., zinc oxide nanowires and copper ammine complex nanowires are formed, and finally encapsulated with polyimide tape.

2. The preparation method according to claim 1, characterized in that The PET has a thickness of 0.3 mm and a size of 3-5 cm x 3-5 cm.

3. The preparation method according to claim 1, characterized in that: The graphene conductive tape is 0.25 mm thick and has a size of 3-5 cm x 1-2 cm.

4. Use of the flexible photodetector prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The flexible photodetector is used in the fields of optical communication and ultraviolet imaging.

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