Fabrication and application of flexible photodetector based on copper-ammonia complex and zinc oxide nanowire stack

Abstract

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

Description

Technical Field

[0001] This invention belongs to the technical field of photoelectric detection and optical wireless communication, specifically relating to the fabrication and application of a flexible photodetector based on (Cu(NH3))(CN) and ZnO nanowire stacking. Background Technology

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

[0003] However, flexible photodetectors still face several unresolved issues, including persistent problems with dark current and photoelectric performance control. Large dark currents reduce the signal-to-noise ratio, increase energy loss, and significantly impact the detection accuracy and lifespan of flexible photodetectors. Therefore, reducing dark current has become a crucial research challenge. Regarding photoelectric performance control, flexible photodetectors face numerous challenges in material and structural design. Response speed and threshold voltage are two key indicators of photoelectric performance in flexible photodetectors; improving response speed and extending threshold voltage have become current research hotspots. Therefore, fabricating flexible photodetectors with excellent electrical and optical properties has profound significance for optical communication applications. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a design method for a flexible photodetector based on the stacking of (Cu(NH3))(CN) and ZnO nanowires, and applies it to the fields of optical communication and ultraviolet imaging.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] The preparation method of a flexible photodetector composed of copper ammonia complex ((Cu(NH3))(CN)) and zinc oxide (ZnO) nanowires is as follows:

[0007] 1) Using PET as a substrate, first clean 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 terminal of the high voltage power supply, and attach graphene tape as an electrode.

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

[0009] 3) After the (CH3COO)2Zn / PEO precursor fiber is prepared, adjust the substrate orientation so that the (CH3COO)2Zn / PEO precursor fiber is at 90° to the direction of motion of the motion platform. Then, prepare the (CH3COO)2Cu / PEO precursor fiber on the same substrate so that the (CH3COO)2Zn / PEO precursor fiber and the (CH3COO)2Cu / PEO precursor fiber are arranged in a cross pattern.

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

[0011] A more preferred embodiment 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 option is that the graphene conductive tape has a thickness of 0.25 mm and a size of 3-5 cm x 1-2 cm.

[0013] The flexible photodetector prepared by the above method 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 this invention makes full use of the coupling of piezoelectric effect and charge trapping effect, which greatly reduces the dark current of ZnONWs and greatly improves the responsivity, which is 13.3 A / W, with rise time and fall time of 11 ms and 9 ms, respectively.

[0016] 2) Select a device with a threshold voltage of 20V (25 stacked layers), and set all biases to a fixed value of 10V. Under a 10V bias, as the stacking increases, the current of the ZnO nanowires gradually decreases from 2.89e-4 to 1.12e-7. Attached Figure Description

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

[0018] Figure 2 This is a schematic diagram of the fabrication process of the photodetector.

[0019] Figure 3 The diagram shows the current response of the photodetector at different numbers of layers.

[0020] Figure 4 The current intensity response diagram is shown for the photodetector with 25 stacked layers.

[0021] Figure 5 The graph shows the switching current of the photodetector as a function of the number of stacked layers.

[0022] Figure 6 , 7 Figure 8 shows the application of this photodetector in ultraviolet communication.

[0023] Figure 9 , 10 Figure 11 shows the application of this photodetector in ultraviolet displays. Detailed Implementation

[0024] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0025] Example 1:

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

[0027] 2) Prepare a particle-free zinc ink containing 5% zinc acetate (by mass), 12% PEO (by mass), water and anhydrous ethanol in a volume ratio of 1:2, and zinc acetate to isopropanolamine in a molar ratio of 1:5. First, dissolve 0.25g of zinc acetate dihydrate in 1.54g of deionized water. After complete dissolution, add 2.43g of ethanol, 0.43g of isopropanolamine, and finally 0.6g of PEO. Seal the container and add magnetic particles. Stir at 25°C for 48 hours.

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

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

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

[0031] 6) After sintering at 50℃, ZnO nanowires and (Cu(NH3))(CN) nanowires are formed. Finally, they are encapsulated with polyimide tape.

[0032] like Figure 1 As shown, on a PET substrate, (Cu(NH3))(CN) is artificially stacked radially on ZnO NWs using electrospinning technology. This fully utilizes the coupling of piezoelectric and charge trapping effects, significantly reducing the dark current of ZnO NWs and improving responsivity, while also providing an adjustable threshold voltage.

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

[0034] like Figure 4 As shown, the flexible photodetector based on (Cu(NH3))(CN) and ZnO nanowire stacking improves performance. With 25 layers of (Cu(NH3))(CN) stacking, the responsivity 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 varies with the number of stacked layers. It can be seen that as the number of stacked layers increases, the proportion of dark current decreases significantly.

[0036] Based on its excellent optoelectronic properties, a simple physical encryption protocol can be established. The sender and receiver use the same mask as the key. The sender extracts the grid information from the mask to modulate the optical signal, while the receiver receives and shields the optical signal by moving the mask. Specifically, the sender and receiver pre-agree on a truth table (including correct, invalid, and obfuscated signals). The sender extracts the grid information on the mask into transparent and opaque grids. At the transparent grids, the sender transmits the correct optical signal; at the opaque grids, the sender transmits a random obfuscated signal. The receiver synchronously moves the mask to receive the correct optical signal and shields the obfuscated signal. Finally, the information is decoded and output according to the agreed truth table.

[0037] As shown in the figure, the ultraviolet communication system includes a transmitter, optical communication, analog front-end, ADC analog-to-digital converter, and display. First, the transmitter and receiver define the encoding of "A" to "Z" from 00000 to 11001, with spaces encoded as 11010, and the others as obfuscated codes. The communication truth table is as follows: Figure 7 Specifically, the sender and receiver pre-agree on a truth table (including correct signals, invalid signals, and scrambled signals). The sender extracts the grid information on the mask into transparent and opaque grids. At the transparent grids, the sender transmits the correct optical signal, and at the opaque grids, the sender transmits random scrambled signals. The receiver synchronously moves the mask to receive the correct optical signal while blocking the scrambled signals. Finally, it decodes and outputs the information according to the agreed truth table. The sender inputs a transmission string on the host computer and transmits binary code by modulating the switch of the ultraviolet laser. After transmission over a certain distance, it is received by the ZnO@(Cu(NH3))(CN) photodetector. The analog front-end mainly includes an amplifier circuit and a filter circuit, used to receive the optical signal and convert it into an electrical signal for preliminary processing. This example uses the transmission of "XMU" as an example, and the waveform on the host computer at the receiving end is as follows. Figure 8 As can be seen, the machine can correctly identify the information transmitted by the sender, and due to the high switching ratio, a certain degree of error is allowed, while the high response speed allows for a high transmission rate.

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

[0039] Based on the excellent photoelectric properties of ZnO@(Cu(NH3))(CN), an ultraviolet imaging system was constructed. For example... Figure 9 As shown, a wavelength of 254nm and a power of 5.6mW / cm were used. 2A hollow template is irradiated with an ultraviolet laser, and ZnO@(Cu(NH3))(CN) is used to receive photoelectric signals. By moving the template, current data is collected using an IV analyzer. After processing and analysis by a computer, the template is colored according to its current intensity to obtain a clear image. Figure 10 Display the results for the letters "XMU". Figure 11 The effect is shown for different stacking layers. It can be seen that when the stacking layer is 25, the word "XMU" can be clearly displayed.

[0040] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for fabricating a flexible photodetector based on copper ammonia complex and zinc oxide nanowire stacking, characterized in that, The specific steps are as follows: 1) Using PET as a substrate, first clean 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 terminal of the high voltage power supply, and attach graphene tape as an electrode. 2) Prepare particle-free zinc ink and particle-free copper ink, store the ink in a syringe, deliver it to the needle through a precision injection pump, prepare conductive fibers using electrospinning direct writing technology, apply a high voltage between the needle and the substrate to generate an electric field force as the driving force to form a stable jet, and prepare (CH3COO)2Zn / PEO precursor fibers on the PET substrate under the traction of the moving platform; 3) After the (CH3COO)2Zn / PEO precursor fiber is prepared, adjust the substrate orientation so that the (CH3COO)2Zn / PEO precursor fiber is at 90° to the direction of motion of the motion platform. Then, prepare the (CH3COO)2Cu / PEO precursor fiber on the same substrate so that the (CH3COO)2Zn / PEO precursor fiber and the (CH3COO)2Cu / PEO precursor fiber are arranged in a cross pattern. 4) After sintering at 50℃, zinc oxide nanowires and copper ammonia complex nanowires are formed, and finally encapsulated with polyimide tape.

2. The preparation method according to claim 1, characterized in that, The PET material 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 0.25mm thick and has a size of 3-5cm x 1-2cm.

4. The application of the flexible photodetector prepared by any one of claims 1-3, characterized in that, The flexible photodetector is used in optical communication and ultraviolet imaging.

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