Planar self-powered optical detection device based on micro-capacitor array and preparation method thereof

Abstract

The application provides a planar self-powered light detection device based on a micro-capacitor array and a preparation method thereof, and the preparation method comprises the following steps: step S1, cleaning and drying an ITO substrate provided with etching lines; step S2, depositing an Sb2S3@PANI composite film on the ITO substrate; step S3, drawing an 'interdigital' channel on the deposited film, and scraping off part of the film, and the remaining Sb2S3@PANI film is used as a negative electrode of a micro-capacitor; step S4, preparing a positive electrode and an electrolyte of the micro-capacitor, and assembling the positive electrode and the electrolyte with the negative electrode of the micro-capacitor to form the planar self-powered light detection device based on the micro-capacitor array. By adopting the technical scheme of the application, the planar common electrode connection between photoelectric detection and power supply energy storage units is realized, the structural redundancy problem caused by the connection circuit of the previous mixed function device is solved, the device integration is higher, the volume is smaller, and the miniaturization and portability are better.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology powered by micro energy storage units, and particularly to a planar self-powered photodetector based on a microcapacitor array and its fabrication method. Background Technology

[0002] With the rapid development of the electronics industry and artificial intelligence, self-powered detection and sensing systems have begun to be widely used in various electronic devices. These devices typically consist of two separate parts: a power supply component that provides sustainable power, and various detection and sensing components. The power supply component, acting as the front end, is mainly composed of various portable power sources, including batteries, fuel cells, lithium batteries, supercapacitors, and solar cells. Initially, the connection between the power supply front end and the detection back end of these self-powered detection devices was primarily achieved through physical connections such as wires. However, this connection method resulted in low integration and large device size, making it difficult to apply to various portable electronic products. Later, with the development of integrated circuit technology, some research began to utilize techniques such as photolithography to replace the original wires with miniature circuits, reducing the redundancy of the entire connection system to some extent. However, this improvement did not fundamentally solve the problems of energy loss and circuit aging / opening caused by physical connections.

[0003] To address these issues, the research field has recently proposed a "shared electrode" connection method. This concept primarily refers to the fabrication of materials with both energy storage and detection capabilities, allowing them to be simultaneously applied to device structures at both the power supply front-end and the detection back-end, achieving a seamless connection between the two. This approach fundamentally realizes a high degree of integration between the power supply front-end and the detection / sensor device, improving the overall integration tightness of the self-powered detection and sensing system. However, limited by the lateral transport capability of particles and the fact that most detection devices have a vertical structure, current research on this integrated structure remains at the stage of three-dimensional stacked devices, and many challenges remain in achieving one-piece planar integration.

[0004] Therefore, based on the above discussion, developing a planar "common electrode" structure for self-powered detection devices can solve many drawbacks of physical circuits while promoting their integration with one-piece integrated circuits, thus better adapting to the trend of electronic products moving towards portability and miniaturization. Summary of the Invention

[0005] To address the above technical problems, this invention discloses a planar self-powered photodetector based on a microcapacitor array and its fabrication method. This device is wire-free, has a higher degree of integration, and is smaller in size.

[0006] The technical solution adopted by this invention is as follows:

[0007] A method for fabricating a planar self-powered photodetector based on a microcapacitor array includes the following steps:

[0008] Step S1: Clean and dry the ITO substrate with etching lines.

[0009] Step S2: Deposit an Sb2S3@PANI composite film on an ITO substrate;

[0010] Step S3: Drill interdigitated channels on the deposited film and scrape off part of the film, leaving the Sb2S3@PANI film as the negative electrode of the microcapacitor unit.

[0011] Step S4: Prepare the positive electrode and electrolyte of the microcapacitor, and assemble them with the negative electrode of the microcapacitor to form a planar self-powered photodetector based on a microcapacitor array.

[0012] As a further improvement of the present invention, in step S1, the ITO substrate is provided with etching lines, and the ITO substrate is ultrasonically cleaned in acetone, ITO cleaning agent, deionized water and isopropanol respectively, and then dried; the cleaned and dried ITO substrate is treated with UV-O3.

[0013] Further preferably, the ITO substrate is ultrasonically cleaned for 10 minutes in acetone, ITO cleaning agent, deionized water and isopropanol respectively, and then dried at 90°C; in addition, before use, the cleaned and dried ITO glass is treated with UV-O3 for 20 minutes to further clean it.

[0014] As a further improvement of the present invention, step S2 includes:

[0015] Step S201: Deposit an Sb2S3 thin film on an ITO substrate;

[0016] In step S202, an ITO substrate with an Sb2S3 film deposited on it is used as the working electrode and immersed in the deposition solution. Ani is electropolymerized in a portion of the Sb2S3 region using cyclic voltammetry to achieve polyaniline composite modification. The substrate is then cleaned and dried.

[0017] As a further improvement of the present invention, in step S201, after depositing the Sb2S3 thin film, it is annealed in a nitrogen atmosphere at a temperature of 200-300°C. More preferably, the annealing temperature is 260°C.

[0018] As a further improvement of the present invention, the annealing time is 20-40 minutes. Preferably, the annealing time is 30 minutes.

[0019] As a further improvement of the present invention, the deposition solution in step S201 is obtained by dissolving an antimony source, a sulfur source, polyvinylpyrrolidone, concentrated hydrochloric acid, and dimethyl sulfoxide in deionized water.

[0020] As a further improvement of the present invention, the antimony source is SbCl3 and the sulfur source is Na2S2O3.

[0021] As a further improvement of the present invention, in step S201, a constant potential deposition method is used for deposition, with a deposition potential of -0.7V to 0.85V and a deposition time of 1 to 20 minutes. More preferably, the deposition potential is -0.85V and the deposition time is 5 minutes.

[0022] As a further improvement of the present invention, after deposition, the film surface is rinsed with ethanol to remove residual impurities and then vacuum dried at room temperature overnight.

[0023] As a further improvement of the present invention, in step S202, the Sb2S3 region used for photodetection remains above the solution surface during the deposition process, and therefore remains a bare Sb2S3 film without PANI deposition; the deposition solution includes aniline monomer and H2SO4, the concentration of aniline monomer is 0.5-1 mol / L, and the concentration of H2SO4 is 0.5-1.5 mol / L.

[0024] As a further improvement of the present invention, after deposition, a small amount of ethanol is used to clean the Sb2S3@PANI film using a dropper to remove incompletely reacted Ani monomers and residual substances from the film. Then, the film is placed in a vacuum drying oven and dried at 50°C for at least 8 hours.

[0025] As a further improvement of the present invention, in step S4, the freeze-dried bacterial cellulose film is immersed in a salt solution for more than 8 hours, and the resulting cellulose hydrogel will be used as the electrolyte of the microcapacitor array; the positive electrode active materials activated carbon, polyvinylidene fluoride, and acetylene black are added to N-methylpyrrolidone solvent and mixed to form a slurry, which is then coated on a cleaned Ti foil and vacuum dried to obtain the positive electrode of the microcapacitor.

[0026] As a further improvement of the present invention, the salt solution includes, but is not limited to, H2SO4 solution and Na2SO4 solution.

[0027] The present invention also discloses a planar self-powered photodetector based on a microcapacitor array, characterized in that it is prepared by the fabrication method of the planar self-powered photodetector based on a microcapacitor array as described in any one of the above claims.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] First, by employing the technical solution of this invention, the multifunctionality of Sb₂S₃ material is utilized. Sb₂S₃ material can be used as an electrode in energy storage devices and also possesses the photoelectric response characteristics of semiconductor thin films. This achieves a wireless connection between the photoelectric detection and power supply / energy storage units, solving the structural redundancy problem caused by connection circuits in previous hybrid devices. This results in higher device integration, smaller size, and greater suitability for miniaturization and portability. The device can respond to as little as 0.5 mW / cm². 2 Visible light of varying intensity generates a potential response, and it can also effectively detect narrow-band light in different wavelength ranges.

[0030] Secondly, by utilizing the unique characteristics of the electrodeposition polymerization method, Sb₂S₃ films can be locally modified, resulting in different properties in different parts of the same Sb₂S₃ film, which can better meet the performance requirements of various functional units. Furthermore, compared to other methods such as photolithography and ion bombardment, electrodeposition polymerization is more convenient, faster, and less expensive.

[0031] Finally, the device obtained by this invention is an integrated planar structure. In the photodetector film and the microcapacitor power supply array, the thickness of each film is in the micrometer range. This structural feature will be more conducive to the integration of the device with integrated circuits and expand its application in portable electronic products. Attached Figure Description

[0032] Figure 1 This is a flowchart of the fabrication process of a planar self-powered photodetector device based on a microcapacitor array according to an embodiment of the present invention, wherein 1 is the negative electrode, 2 is the photodetector Sb2S3 thin film, and 3 is the positive electrode.

[0033] Figure 2 These are schematic diagrams and cross-sectional views of a planar self-powered photodetector based on a microcapacitor array according to an embodiment of the present invention; wherein, a) is a schematic diagram, b) is a cross-sectional view, 1 is the negative electrode, 2 is the photodetector Sb2S3 thin film, and 3 is the positive electrode.

[0034] Figure 3 These are the electrochemical performance of the microcapacitor array portion of the present invention; wherein, (a) is the cyclic voltammetry curve and (b) is the constant current charge-discharge curve.

[0035] Figure 4 After charging according to an embodiment of the present invention, at a light intensity of 200mW / cm² 2 Self-discharge curve under illumination.

[0036] Figure 5 This is an embodiment of the invention at 200mW / cm 2 Potential change curves after baseline removal at light intensity and 100s illumination cycle.

[0037] Figure 6 This is an embodiment of the invention at 200mW / cm 2 Potential change curves after baseline removal at light intensity and 50s illumination cycle.

[0038] Figure 7 This is an embodiment of the invention at 200mW / cm 2 Potential change curves after baseline removal under light intensity and 30s illumination cycle.

[0039] Figure 8 This invention presents the photoelectric response performance under different light intensities when the illumination period is 100s. Among them, (a) is the potential change curve after baseline removal, and (b) is the trend of the absolute value of photogenerated potential with light intensity, as well as the corresponding fitting curve.

[0040] Figure 9 This embodiment of the invention operates at a light intensity of 100 mW / cm. 2 Potential change curves after the baseline is reached when different wavelengths of light are used for illumination with a light period of 50s. Detailed Implementation

[0041] The preferred embodiments of the present invention will be described in further detail below.

[0042] Example 1

[0043] A method for fabricating a planar self-powered photodetector based on a microcapacitor array includes the following steps:

[0044] (1) Having such Figure 1 The ITO glass with parallel etching lines shown was ultrasonically cleaned for 10 minutes each in acetone, ITO cleaning agent, deionized water, and isopropanol, and then dried overnight in a drying oven at 90°C. Additionally, before use, the cleaned and dried ITO glass was treated with UV-O3 for 20 minutes for further cleaning.

[0045] (2) A two-step electrodeposition method was used to deposit Sb2S3@PANI composite films on a cleaned and dried ITO substrate. The specific process is as follows: Figure 1 As shown:

[0046] a. Preparation of the precursor solution for Sb₂S₃ electrodeposition. The deposition solution uses SbCl₃ as the antimony source and Na₂S₂O₃ as the sulfur source. Polyvinylpyrrolidone (PVP), a small amount of concentrated hydrochloric acid, dimethyl benzoate (DMSO), and deionized water are also added to prepare the solution. Concentrated hydrochloric acid effectively inhibits the hydrolysis reaction of the salt solution, while DMSO promotes the dissolution of PVP, significantly reducing the overall viscosity of the deposition solution.

[0047] b. The deposition of the Sb₂S₃ thin film was carried out in a three-electrode system, using an ITO electrode with special etching lines, a graphite sheet, and a saturated calomel electrode as the working electrode, counter electrode, and reference electrode, respectively. A potentiostatic deposition method was employed, with a deposition potential of -0.85V and a deposition time of 5 min. After deposition, the film surface was rinsed with ethanol to remove residual impurities and then vacuum-dried overnight at room temperature. Subsequently, the Sb₂S₃ thin film was annealed at 260℃ for 30 min in a nitrogen atmosphere to improve its crystallinity.

[0048] c. Using ITO glass with a deposited Sb₂S₃ film as the working electrode, polyaniline (PANI) composite modification was performed on a portion of the Sb₂S₃ region via cyclic voltammetry. The concentration of aniline (Ani) monomer in the deposition solution included, but was not limited to, 0.5 M, and 1 M H₂SO₄ was required for proton doping. The deposition process still employed a three-electrode system, performing electropolymerization of Ani at different scan rates within a potential range of -0.2 V to 1 V. It should be noted that the Sb₂S₃ region used for photodetection remained above the solution surface during deposition, therefore the aforementioned electropolymerization reaction did not occur, and it remained as bare Sb₂S₃.

[0049] After deposition, a small amount of ethanol was used to wash the PANI film with a dropper to remove incompletely reacted Ani monomers and residual sulfuric acid. The film was then placed in a vacuum drying oven and dried at 50°C for at least 8 hours.

[0050] (3) Figure 1 As shown, "interdigitated" channels are etched on the deposited film with a glass cutter, and part of the film is scraped off. The remaining Sb2S3@PANI film will serve as the negative electrode 1 of the microcapacitor array, and the exposed Sb2S3 film will serve as the photodetector Sb2S3 film 2.

[0051] (4) Polyvinylidene fluoride (PVDF), acetylene black, and activated carbon (AC) were mixed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 1:1:8 to prepare a slurry, which was then coated onto a cleaned Ti foil. The AC-coated Ti foil was dried in a vacuum drying oven at 70°C for 2 hours. According to the charge balance theory, the area of ​​the positive electrode should be half the area of ​​the negative electrode. Therefore, AC / Ti was cut to the appropriate size and used as the positive electrode 3 of the microcapacitor, and pasted into the corresponding position of the positive electrode in the interdigitated pattern of each microcapacitor unit, such as... Figure 1 and Figure 2 As shown in (a).

[0052] (5) The freeze-dried bacterial cellulose membrane is immersed in a salt solution overnight. The resulting cellulose hydrogel will be used as the electrolyte of the microcapacitor array and will cover the interdigitated positive and negative electrodes. The types of salt solutions include, but are not limited to, H2SO4 and Na2SO4, and the molar concentrations of the solutions include, but are not limited to, 0.5M, 1M, and 2M.

[0053] The self-powered photodetector device based on a microcapacitor array, fabricated through the above process, has the following final device structure and photograph: Figure 1 and Figure 2 As shown, the bare Sb2S3 film without PANI composite, i.e. the photodetector Sb2S3 film 2, serves as the photodetector region and is connected to the microcapacitor array, which serves as the power supply unit, through the Sb2S3@PANI electrode, i.e. the negative electrode 1.

[0054] Example 2

[0055] Using the AC / / Sb2S3@PANI microcapacitor array of the self-powered photodetector based on a microcapacitor array prepared in Example 1 as the power supply unit, the Sb2S3 thin film as the detection sensing unit, the cellulose impregnation solution as 0.5M H2SO4, and the resulting cellulose hydrogel as the electrolyte, electrochemical performance tests were performed. The cyclic voltammetry curve and the constant current charge-discharge curve are shown below. Figure 3 As shown, Figure 3 Curves a, b, c, d, and e in (a) are cyclic voltammetry curves at scan rates of 10 mV / s, 20 mV / s, 30 mV / s, 50 mV / s, and 100 mV / s, respectively. Figure 3 In (b), curves f, g, h, i, j, and k represent current densities of 0.25 mA / cm², respectively. 2 0.3mA / cm 2 0.4mA / cm 2 0.6mA / cm 2 0.8mA / cm 2 1.0 mA / cm 2 The constant current charge-discharge curves are shown below. Figure 3 It is known that the AC / / Sb2S3@PANI microcapacitor array in this device, after charging, can provide a maximum voltage of 5.6V for photodetection. This voltage is achieved through... Figure 2 (b) shows a common electrode applied to the exposed photodetector Sb₂S₃ thin film 2 for the separation of photogenerated "hole-electron" pairs. Subsequently, photogenerated electrons are attracted to the positive electrode of the microcapacitor array, while photogenerated holes move to the negative electrode side through the external circuit, thereby generating a photogenerated electromotive force. This potential change under illumination is ultimately reflected in the open-circuit potential curves across the microcapacitor array.

[0056] Example 3

[0057] The self-powered photodetector based on a microcapacitor array obtained in Example 1 was charged and then tested, with the light source always at 200mW / cm². 2 Visible light, in a "light-dark" test cycle, with equal periods of light and no light, the self-discharge curve is as follows: Figure 4 As shown, at the start of illumination, the potential drops. This potential change is caused by the separation and directional movement of photogenerated carriers. Under the influence of the open-circuit potential of the microcapacitor, the movement of photogenerated electrons (photogenerated holes) accelerates the charge neutralization between the positive and negative electrodes of the capacitor, thus accelerating the capacitor discharge process. When illumination ends, the above effect disappears, and the potential on both sides of the microcapacitor array rises again, but only to a level slightly lower than the initial potential before illumination. This is because the microcapacitor itself generates a self-discharge effect during this process. Therefore, in the photodetection process, the self-discharge curve of the microcapacitor array is defined as the baseline of the potential change curve. Figures 5-7 The potential change curves after baseline removal are shown for different test cycle durations.

[0058] like Figure 5 As shown, when the illumination and darkness periods are both 100s, the average detectable potential change is 0.382V; Figure 6 As shown, when the illumination and darkness time are both 50s, the average value of the potential change is 0.363V; Figure 7 As shown, when the illumination and darkness periods are both 30 seconds, the average potential change is 0.334V. Figures 5-7 It can be seen that under different illumination durations, the potential decreases sharply within the first few seconds of illumination, and then gradually becomes more gradual. Therefore, it can be seen that when the illumination duration is reduced from 100s to 30s, the change in potential does not decrease significantly.

[0059] The above analysis shows that the planar self-powered detector fabricated in this example can detect 200mW / cm². 2 Visible light enables instantaneous detection, and the photoelectric conversion signal is displayed as a significant change in potential.

[0060] Example 4

[0061] Based on Example 3, in this example, the light source is visible light of varying intensity. Within one test cycle, the illumination and no-illumination times are both fixed at 100 seconds. The photoelectric response performance curves under different light intensities are shown below. Figure 8 As shown. Figure 8 In (a), curves a, b, c, d, e, and f represent light intensities of 200 mW / cm², respectively. 2 160mW / cm 2 100mW / cm 2 25mW / cm 22.68mW / cm 2 0.5mW / cm 2 The potential change curve at time.

[0062] like Figure 8 As shown in (b), under the aforementioned light intensities, the absolute values ​​of the potential changes (i.e., the photogenerated voltage values) are 0.375V, 0.313V, 0.288V, 0.237V, 0.063V, and 0.038V, respectively. According to the fitted curves, the trend of the photogenerated voltage value with light intensity can be divided into two parts: when the light intensity is less than 25mW / cm²... -2 When the light intensity is greater than 25 mW cm⁻¹, the photovoltage increases rapidly and linearly with increasing light intensity; when the light intensity is greater than 25 mW cm⁻¹, the photovoltage increases rapidly and linearly with increasing light intensity. -2 At this point, the increase in photogenerated voltage tends to level off, and its relationship with light intensity is no longer linear, but rather exhibits a quadratic function relationship. The formula for the fitted curve is as follows: Figure 8 As shown in (b).

[0063] In summary, in this embodiment, the planar self-powered detector of the present invention can respond to visible light of different intensities. The lowest light intensity at which a response can be generated can reach 0.5 mW / cm². 2 .

[0064] Example 5

[0065] Based on Example 3, in this example, the intensity of the light source is 100mW / cm². 2 With both illumination and no-illumination periods fixed at 50 seconds, the potential change curves after baseline removal under different wavelengths of light are shown below. Figure 9 As shown, the wavelength ranges of blue, green, and red light are 380–500 nm, 500–600 nm, and 600–700 nm, respectively.

[0066] Depend on Figure 9 It can be seen that the photogenerated voltage values ​​of the device are 0.168V, 0.132V and 0.091V under blue, green and red light band illumination, respectively.

[0067] In summary, the planar self-powered detector in this embodiment can respond to light in different narrow bands.

[0068] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a planar self-powered photodetector based on a microcapacitor array, characterized in that, Includes the following steps: Step S1: Clean and dry the ITO substrate with etching lines. Step S2: Deposit an Sb2S3@PANI composite film on an ITO substrate; Step S3: Drill "interdigitated" channels on the deposited film and scrape off part of the film, leaving the Sb2S3@PANI film as the negative electrode of the microcapacitor unit. Step S4: Prepare the positive electrode and electrolyte of the microcapacitor, and assemble them with the negative electrode of the microcapacitor to form a planar self-powered photodetector based on a microcapacitor array. Step S2 includes: Step S201: Deposit an Sb2S3 thin film on an ITO substrate; In step S202, an ITO substrate with an Sb2S3 film deposited on it is used as the working electrode and immersed in the deposition solution. Ani is electropolymerized in a portion of the Sb2S3 region using cyclic voltammetry to achieve polyaniline composite modification. The substrate is then cleaned and dried.

2. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 1, characterized in that: In step S201, after depositing the Sb2S3 thin film, it is annealed in a nitrogen atmosphere at a temperature of 200-300℃.

3. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 2, characterized in that: The precipitate in step S201 is obtained by dissolving antimony source, sulfur source, polyvinylpyrrolidone, concentrated hydrochloric acid, and dimethyl sulfoxide in deionized water.

4. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 3, characterized in that: In step S201, the antimony source is SbCl3 and the sulfur source is Na2S2O3; the deposition is carried out by constant potential deposition method, the deposition potential is -0.7 V to -0.85 V, and the deposition time is 1 to 20 min.

5. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 1, characterized in that: In step S202, the Sb2S3 region used for photodetection remains above the solution surface during the deposition process; The deposition solution comprises aniline monomer and H2SO4, wherein the concentration of aniline monomer is 0.5-1 mol / L and the concentration of H2SO4 is 0.5-1.5 mol / L.

6. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 1, characterized in that: In step S1, the ITO substrate has etching lines. The ITO substrate is ultrasonically cleaned in acetone, ITO cleaning agent, deionized water and isopropanol respectively, and then dried. The cleaned and dried ITO substrate is then treated with UV-O3.

7. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 1, characterized in that: In step S4, the freeze-dried bacterial cellulose film is immersed in a salt solution for more than 8 hours, and the resulting cellulose hydrogel will be used as the electrolyte of the microcapacitor array. The positive electrode active materials activated carbon, polyvinylidene fluoride, and acetylene black are added to N-methylpyrrolidone solvent to form a slurry, which is then coated on a cleaned Ti foil and vacuum dried to obtain the positive electrode of the microcapacitor.

8. The method for fabricating a planar self-powered photodetector based on a microcapacitor array according to claim 7, characterized in that: The salt solution contains H2SO4 or Na2SO4.

9. A planar self-powered photodetector based on a microcapacitor array, characterized in that: It is prepared using the fabrication method of planar self-powered photodetector based on microcapacitor array as described in any one of claims 1 to 8.

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