Paper-based flexible optical detection device and reconstruction method and preparation method thereof

Abstract

The invention discloses a paper-based flexible optical detection device and a reconstruction method and a preparation method thereof, and relates to the field of flexible image sensing. The reconstruction method comprises the following steps of: performing a compiling process, namely applying bias voltage to two ends of the device, and irradiating the device by using ultraviolet light to form a non-volatile built-in electric field in the device; carrying out an implementation process, namely irradiating the device by using visible light under zero bias voltage, measuring the light current of the device, and modulating the size of the light current by bias voltage applied in the compiling process; and performing a resetting process, namely applying voltage opposite to the compiling process to two ends of the device so as to eliminate the built-in electric field and enable the photoelectric response of the device to be reset. The device has the image sensing capability, the photocurrent of the device is repeatedly adjusted by changing the bias voltage, and the reconstruction performance of the device is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible image sensing, and more particularly to a paper-based flexible light detection device and a reconstruction method and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for picture processing in artificial intelligence computing, the traditional computer adopting the Von Neumann architecture has a centralized data processing design, which leads to a large amount of time and energy for operation, which limits the ability of the computer to process complex artificial intelligence computing. In addition, the diversification of artificial intelligence application scenarios also puts forward new requirements for the flexibility of the detection device. In order to cope with this challenge, the development of a reconfigurable flexible light detection array image sensor has become a focus. However, the manufacture of a light detection array with a reconfiguration function requires a complex and expensive process, which is not conducive to its large-scale and low-cost production. More importantly, the reliability of traditional inorganic semiconductor materials is poor when they are bent, and it is difficult to realize an efficient flexible light detection array on a flexible substrate. The light responsivity of the traditional light detection device is fixed and cannot realize complex on-chip computing operations. In the face of complex image recognition, a large amount of data is generated, which greatly consumes the operation cost. Therefore, it is urgent to develop a new type of low-cost and highly flexible reconfigurable light detection array device, and how to reconfigure its optoelectronic performance through optoelectronic stimulation is also a problem to be solved. SUMMARY

[0003] The purpose of the present application is to overcome the problems of the prior art, provide a paper-based flexible light detection device and a reconstruction method and a preparation method thereof, which can realize an efficient flexible light detection array with a reconfiguration function on a flexible substrate and realize the reconfiguration of its optoelectronic performance through optoelectronic stimulation.

[0004] To achieve the above-mentioned purpose of the application, the first aspect of the present application provides a reconstruction method of a paper-based flexible light detection device, comprising: performing a compiling process, applying a bias voltage to both ends of the device, and irradiating the device with ultraviolet light at the same time to form a non-volatile built-in electric field inside the device; performing an implementation process, irradiating the device with visible light under zero bias voltage, and measuring the photocurrent, the magnitude of the photocurrent being modulated by the bias voltage applied in the compiling process; performing a reset process, applying a voltage opposite to the compiling process to both ends of the device to eliminate the built-in electric field and reset the photoelectric response of the device.

[0005] Preferably, the wavelength of the ultraviolet light used in the compiling process is 385 nm, and the wavelength of the visible light used in the implementation process is 520 nm.

[0006] Preferably, the bias voltage applied in the compiling process ranges from -80V to +80V.

[0007] Preferably, the voltage applied in the resetting process is 80V opposite to the compiling voltage.

[0008] Preferably, to achieve the object of the present application, in the second aspect, the present application further provides a paper-based flexible light detection device, which is reconfigured by using the reconfiguration method of the paper-based flexible light detection device according to the first aspect of the above technical solution, and the device comprises: a flexible substrate, which is a cellulose-based filter paper; interdigital electrodes and connecting lines arranged on the flexible substrate; a perovskite nanocrystal material located in the interdigital electrode region, which is formed on the cellulose-based filter paper by an in-situ synthesis method and forms an ohmic contact with the interdigital electrodes.

[0009] Preferably, the device can be non-volatile modulated in its photoelectric response characteristics by photoelectric stimulation.

[0010] Preferably, the interdigital electrodes and connecting lines are composed of graphene material.

[0011] Preferably, the perovskite nanocrystal material is MAPbBr3 nanocrystal.

[0012] Preferably, the metal halide perovskite material comprises MABr and PbBr2, which are dissolved in a DMF solution in a molar ratio of 1:1.

[0013] To achieve the object of the present application, in the third aspect, the present application further provides a preparation method of a paper-based flexible light detection device, which is used to prepare a paper-based flexible light detection device according to the second aspect of the above technical solution, and the preparation method comprises the following steps: preparing a perovskite precursor solution; forming interdigital electrodes and connecting lines on a cellulose-based filter paper; applying the perovskite precursor solution to the interdigital electrode region; performing heat treatment to synthesize perovskite nanocrystals on the filter paper by in-situ synthesis of perovskite precursors.

[0014] Compared with the prior art, the present application has the following beneficial effects: The present application uses high-flexibility flexible material as a flexible substrate, constructs corresponding electrode structures and interconnection wires on the flexible substrate, and in-situ synthesizes semiconductor perovskite nanocrystals in the light-responsive pixel area, to prepare a high-flexibility perovskite nanocrystal-based flexible light detection array device. Compared with the prior art, the flexible light detection array device has low cost, high flexibility, and obvious photoconductivity, has image transmission capability, and the dark current and photocurrent can both show good stability in bending cycles. When used, the light responsivity of the device can be adjusted by irradiating ultraviolet laser under a certain bias, and this process can be repeated to realize the reconfigurability of the device. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A schematic diagram of the steps of a reconfiguration method of a paper-based flexible light detection device; Figure 2 A preparation schematic diagram of the in-situ synthesized perovskite nanocrystal / paper composite material in the present application is shown. Figure 3 A finished product of a paper-based reconfigurable flexible light detection device array and a real photo of photoluminescence phenomenon under 385 nm ultraviolet light irradiation are shown. Figure 4 A schematic diagram of the compiling process and implementation process of the reconfigurable flexible light detection device is shown. Figure 5 A statistic of the photocurrent size of the reconfigurable flexible light detection device under irradiation of 385 nm ultraviolet light at different voltages is shown. Figure 6 A statistic of the photocurrent and light responsivity size under zero bias after the compiling process at different voltages is shown. Figure 7 A performance comparison of the reconfigurable flexible light detection device under a 180° bending state and after bending 180° for 10000 times is shown. Figure 8 A pattern output by the reconfigurable flexible light detection device after image preprocessing obtained by computer simulation is shown. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0017] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods have not been described in detail in order to avoid obscuring the present application.

[0018] Embodiment 1 Please refer to Figure 1 The embodiment 1 of the present application provides a reconstruction method of a paper-based flexible light detection device, comprising: S1: performing a compiling process, comprising applying a bias voltage at both ends of the device, while irradiating the device with ultraviolet light, to form a non-volatile built-in electric field inside the device; S2: performing an implementation process, comprising irradiating the device with visible light under zero bias voltage, and measuring the photocurrent, the size of the photocurrent being modulated by the bias voltage applied in the compiling process; S3: performing a reset process, comprising applying a voltage opposite to the compiling process at both ends of the device to eliminate the built-in electric field and reset the photoelectric response of the device.

[0019] The specific contents of steps S1-S3 include: The photoelectric properties of the device are changed by a specific method, which is divided into three steps: compiling process, implementation process, and reset process. Compiling process: by applying different sizes and polarities of voltage at both ends of the device, ultraviolet light is irradiated. This process forms a built-in electric field inside the device, and the electric field will not disappear when the voltage disappears. Implementation process: irradiate the perovskite region with visible light (such as 520nm green laser). The device will generate photocurrent due to laser irradiation, and the size of the photocurrent will change with the size of the voltage applied in the compiling process. Reset process, apply a voltage of 80V opposite to the compiling process at both ends of the device to reset the electric field.

[0020] Specifically, under a bias voltage of -80V~80V, irradiation with 385nm ultraviolet light can complete the compiling. After completing the compiling process, irradiate with 520nm green light under zero bias voltage, and count the size of the photocurrent. Among them, -50V and 50V bias voltage is applied at both ends of the device for 15 seconds, while 385nm laser with a power of 88.5mW / cm2 is irradiated for 4S, then 520nm green light with a power of 30.5mW / cm2 is irradiated under zero bias voltage, and the output photocurrent size is -50.1 nA and 38.6 nA, respectively.

[0021] Embodiment 2 The embodiment 2 based on embodiment 1 provides a paper-based flexible light detection device, which applies the reconstruction method of a paper-based flexible light detection device described in embodiment 1, and the device specifically comprises: A flexible substrate, wherein the flexible substrate is cellulose-based filter paper; Interdigitated electrodes and connecting lines disposed on the flexible substrate; The perovskite nanocrystal material located in the interdigitated electrode region is formed on the cellulose-based filter paper through in-situ synthesis and forms an ohmic contact with the interdigitated electrode.

[0022] The device can non-volatilely modulate its photoelectric response characteristics through photoelectric stimulation. The interdigitated electrodes and connecting wires are made of graphene. The perovskite nanocrystal material is MAPbBr3 nanocrystals.

[0023] The device also exhibits excellent flexibility. After undergoing a 180° mechanical bending test, there was no significant difference in the device's performance, demonstrating its superior mechanical flexibility.

[0024] Example 3 This embodiment 3, based on embodiment 2, provides a method for fabricating a paper-based flexible photodetector device, used to fabricate a paper-based flexible photodetector device as described in embodiment 2. The fabrication method includes the following steps: Preparation of perovskite precursor solution; Interdigitated electrodes and connecting wires are formed on cellulose-based filter paper; The perovskite precursor solution is applied to the interdigitated electrode region; Heat treatment is performed to synthesize perovskite nanocrystals in situ on the filter paper from the perovskite precursor.

[0025] This invention uses highly flexible cellulose filter paper as a substrate, draws interdigitated electrodes and connecting lines on the filter paper, and synthesizes semiconductor perovskite nanocrystals in situ in the interdigitated electrode region to manufacture a paper-based, reconfigurable, mechanically flexible perovskite nanocrystal photodetector array device.

[0026] The specific fabrication process of the device is as follows: Step 1: Using MABr and PbBr2 solids as raw materials, dissolve them in DMF solution at a molar ratio of 1:1 to obtain a concentration of 1 mol / L. Stir and heat at 45°C for 2 hours to prepare a perovskite precursor solution for later use.

[0027] Step 2: As Figure 2As shown in Figure a, commercially available cellulose filter paper is taken and cut into the required specifications and shapes (such as 2cm*2cm blocks). Interdigitated electrodes and connecting lines are sprayed onto the filter paper using graphene spray paint and a mask. The photodetector array electrode structure and interconnecting wires are drawn on the paper (the two ends of the electrodes can be distributed on the same side of the paper substrate to form a planar device structure, or they can be distributed on two sides of the paper substrate to form a vertical device structure). The drawn electrode array defines the photoresponse pixel region of the photodetector array.

[0028] Step 3: As Figure 2 As shown in Figure b, use a pipette to take an appropriate amount of the perovskite precursor solution prepared in step one and drop it onto the filter paper in the pixel area (the interdigitated electrode area of ​​the filter paper) defined in step 2, or use an inkjet printer to print the perovskite precursor solution onto the filter paper to form a photoresponsive pixel array of a certain size; Figure 2 As shown in d, the device was then heated at 100°C for 10 minutes and then allowed to cool naturally at room temperature to complete the device fabrication.

[0029] The perovskite precursor solution attaches to and crystallizes on the fibers of filter paper to grow into nanocrystals. These nanocrystals are sufficiently stable under the protection of cellulose, and the composite material emits green fluorescence under ultraviolet light.

[0030] The reconfigurable flexible photodetector obtained above uses cellulose paper as a substrate, in-situ synthesized perovskite nanocrystals as the photoresponse material, and graphene as electrodes and interconnects. A real-world image of the finished product is shown below. Figure 3 a and Figure 3 As shown in Figure b, this device appears yellow under natural light and exhibits significant photoluminescence under ultraviolet light. These phenomena demonstrate the successful in-situ synthesis of perovskite quantum particles on cellulose-based filter paper. The flexible photodetector array device described exhibits significant modulated characteristics and bending stability.

[0031] To demonstrate the beneficial effects, the following tests were conducted: like Figure 4 As shown, the invention performs a compilation process by irradiating the device with ultraviolet light at different voltages, and records the photocurrent magnitude when the device is irradiated with visible light during the implementation process. The photocurrent statistics under different voltages in this process are as follows: Figure 5 As shown. After the compilation process under different voltages, the magnitudes of the photocurrent and photoresponsivity under visible light are as follows. Figure 6 As shown.

[0032] Conclusion: In the fabricated paper-based reconfigurable flexible photodetector, the electrodes prepared by graphene spraying form a good ohmic contact with the perovskite nanocrystals, indicating that the perovskite nanocrystals synthesized in situ on the cellulose paper substrate possess significant semiconductor photoconductive properties. Furthermore, the device exhibits a clearly modulated photocurrent, showing a significant difference in current magnitude under green laser irradiation after reconstruction, reflecting the device's excellent performance. This demonstrates that the invention possesses on-chip processing capabilities, making the device a promising candidate for complex image processing and image classification.

[0033] To demonstrate the high flexibility of paper-based reconfigurable flexible photodetectors, such as... Figure 7 a and Figure 7 As shown in Figure b, the photoelectric properties of the invention are compared in a bent state and a non-bent state. Figure 7 c and Figure 7 As shown in Figure d, after performing the compilation process under different voltages, the photocurrent of the implementation process was statistically analyzed and compared. It was observed that there was no significant difference in photocurrent magnitude between the bent and unbent states. To further demonstrate the high flexibility of this invention, the photoelectric performance of the device was measured after multiple bends, such as... Figure 7 China and Figure 7 As shown in f. The results are as follows. Figure 7 Zhongg and Figure 7 As shown in Figure h, the device's performance did not significantly degrade after being subjected to 10,000 bends, demonstrating that the device possesses high mechanical flexibility.

[0034] Conclusion: In this composite material, cellulose paper is not only a key carrier for the in-situ synthesis of perovskite nanocrystals, but also provides stable binding sites, effectively passivating the nanocrystals and ensuring they do not detach when the device is bent, thus maintaining the stability of photoelectric performance. Simultaneously, the flexibility of the cellulose paper itself provides the device with high bendability. Therefore, cellulose paper as a substrate is not only crucial for the synthesis of perovskite nanocrystals, but also lays the foundation for the device's flexibility. This makes the device a promising candidate for applications in wearable devices, smart textiles, and biomedical monitoring.

[0035] For a photodetector device composed of multiple pixel arrays, this invention, combined with its reconfigurable characteristics, enables on-chip computing. For example... Figure 8 As shown in Figure a, in a 3x3 detector array, by adjusting the photoresponsivity of each pixel and processing the output current using Kirchhoff's current theorem, on-chip computation and output of a pre-processed image can be achieved. To demonstrate the feasibility of on-chip computation, the device was simulated using computer simulation, and the on-chip processing results were compared with the computer simulation results. The output result of the computer performing matrix operations on the image is shown below. Figure 8 b, Figure 8c and Figure 8 As shown in Figure d, the left image is the processed image, and the right image is the matrix used in the matrix operations. The output results of the on-chip computation are as follows. Figure 8 e, Figure 8 f and Figure 8 As shown in Figure g, the left image is the processed image, and the right image is the voltage matrix used in the on-chip computation. The comparison between the matrix computation results and the on-chip computation results shows no significant difference, proving the feasibility of the on-chip computation method of this invention.

[0036] Conclusion: By leveraging the reconfigurability feature, the photoresponsivity of each pixel can be precisely defined, and the preprocessed result can be obtained by combining it with Kirchhoff's current theorem. This calculation process does not require matrix operations within the computer, thus significantly reducing computing time and power consumption. This lays the foundation for more complex artificial intelligence image recognition technologies.

[0037] Through the above embodiments and analysis, it can be concluded that this invention designs a paper-based reconfigurable flexible photodetector. Scientifically significant conclusions have been drawn, providing important guidance for material selection and structural design in this field. The described flexible photodetector array possesses excellent photodetection performance, reconfiguration performance, and mechanical flexibility. Its photoresponsivity can be altered through specific methods, and on-chip image processing is achieved, providing a novel approach for more complex artificial intelligence image sensing technologies.

[0038] In summary, this invention can alter the photoelectric properties of a device through photoelectric stimulation, allowing it to adjust the photocurrent to visible light under zero bias, a process known as reconfiguration. A flexible, reconfigurable perovskite photodetector array based on cellulose paper was designed. Highly flexible cellulose paper was selected as the substrate, and perovskite nanocrystals were synthesized in situ within the filter paper to complete the device fabrication. Furthermore, because the nanocrystals are synthesized in situ within the filter paper, the device is less prone to nanocrystal detachment during bending, which could weaken its performance. In testing, the device maintained good photoelectric performance even after multiple bends. This photodetector device possesses on-chip computing capabilities to address problems such as complex pattern image processing and image classification.

[0039] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A reconstruction method for a paper-based flexible photodetector, characterized in that, Includes the following steps: During the compilation process, a bias voltage is applied across the two ends of the device, and the device is simultaneously irradiated with ultraviolet light to form a non-volatile built-in electric field inside the device. In the implementation process, the device is irradiated with visible light under zero bias, and its photocurrent is measured. The magnitude of the photocurrent is modulated by the bias voltage applied during the compilation process. A reset process is performed by applying a voltage opposite to that of the compilation process across the two ends of the device to eliminate the built-in electric field and reset the device's photoelectric response.

2. The reconstruction method according to claim 1, characterized in that, The ultraviolet light wavelength used in the compilation process is 385nm, and the visible light wavelength used in the implementation process is 520nm.

3. The reconstruction method according to claim 2, characterized in that, The bias voltage applied during the compilation process ranges from -80V to +80V.

4. The reconstruction method according to claim 1, characterized in that, The voltage applied during the reset process is 80V, which is the reverse of the compilation voltage.

5. The reconstruction method according to claim 1, characterized in that, The method is used to independently program the photoresponsivity of one or more pixels in a photodetector array composed of multiple of the aforementioned devices, so as to realize image processing functions within the sensor.

6. A paper-based flexible photodetector device, using the reconstruction method of any one of claims 1 to 5, characterized in that, The device includes: A flexible substrate, wherein the flexible substrate is cellulose-based filter paper; Interdigitated electrodes and connecting lines disposed on the flexible substrate; The perovskite nanocrystal material located in the interdigitated electrode region is formed on the cellulose-based filter paper through in-situ synthesis and forms an ohmic contact with the interdigitated electrode.

7. The device according to claim 6, characterized in that, The device can non-volatilely modulate its photoelectric response characteristics through photoelectric stimulation.

8. The device according to claim 6, characterized in that, The interdigitated electrodes and connecting wires are made of graphene material.

9. The device according to claim 6, characterized in that, The perovskite nanocrystalline material is MAPbBr3 nanocrystalline.

10. A method for preparing a paper-based flexible photodetector, used to prepare a paper-based flexible photodetector as described in any one of claims 6-9, characterized in that, The preparation method includes the following steps: Preparation of perovskite precursor solution; Interdigitated electrodes and connecting wires are formed on cellulose-based filter paper; The perovskite precursor solution is applied to the interdigitated electrode region; Heat treatment is performed to synthesize perovskite nanocrystals in situ on the filter paper from the perovskite precursor.

Images