Hydrovolt device and preparation method thereof

Abstract

The invention discloses a water photovoltaic device and a preparation method thereof. The water photovoltaic device comprises a nanowire layer, a top electrode arranged at the top of the nanowire layer, and a bottom electrode arranged at the bottom of the nanowire layer, wherein the top electrode comprises conductive microspheres distributed at the top of the nanowire layer, and the conductive microspheres are in electric contact with the top of the nanowire layer so as to conduct nanowires in the nanowire layer. According to the water photovoltaic device and the preparation method thereof, the conductive microspheres are used as the top electrode of the device, good electric contact with the top ends of the nanowires of the device can be formed, charges in the nanowires are efficiently collected, the charges are guided out through communication between the conductive microspheres, and the output performance of the device can be remarkably improved; therefore, wide application of the catalyst in the field of renewable energy sources is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a hydrovoltaic device and a preparation method thereof. Background Art

[0002] In the field of renewable energy technology research, a phenomenon called the "hydrovoltaice effect" has received widespread attention in recent years. This effect is based on the directional movement of water on the surface of solid materials, which can drive the double electric layer on the liquid-solid interface to move, resulting in the accumulation of positive and negative charges in different directions and generating electromotive force. This mechanism provides a new way to convert the mechanical energy of microscopic movement in water, such as water evaporation, flow or droplet movement, into electrical energy.

[0003] Nanomaterials have shown great potential in energy harvesting based on the hydrovoltaic effect due to their huge specific surface area and significant surface effect. They can effectively collect microscopic mechanical energy in water and generate considerable electromotive force, thus forming hydrovoltaic devices (HDs) that can supply power to the outside. Silicon nanowires, as an important nanomaterial, have been used to prepare HDs. The working principle of silicon nanowire hydrovoltaic devices is to use silicon nanowires to capture microscopic mechanical energy in water and convert it into electrical energy through the hydrovoltaic effect. However, the output performance of existing silicon nanowire hydrovoltaic devices is poor, which limits their wide application in the energy field.

[0004] Therefore, it is necessary to provide a new solution to the problems in the prior art. Summary of the invention

[0005] The object of the present invention is to provide a hydrovoltaic device and a preparation method thereof, which can improve the output performance of the hydrovoltaic device.

[0006] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a hydrovoltaic device comprising: a nanowire layer, a top electrode disposed on the top of the nanowire layer, and a bottom electrode disposed on the bottom of the nanowire layer; wherein the top electrode comprises conductive microspheres distributed on the top of the nanowire layer, the conductive microspheres being in electrical contact with the top of the nanowire layer to conduct the nanowires in the nanowire layer.

[0008] In one or more embodiments, the conductive microspheres have a diameter of 1 to 100 μm.

[0009] In one or more embodiments, the distribution amount of the conductive microspheres on the top of the nanowire layer is 0.1 to 100 mg / cm 2 .

[0010] In one or more embodiments, the conductive microspheres include polymer microspheres and a conductive layer coated on the outer surface of the polymer microspheres, the polymer microspheres are made of polystyrene, and the conductive layer is made of nickel.

[0011] In one or more embodiments, the top of the nanowire layer is coated with a conductive coating, and the conductive microspheres cover the conductive coating.

[0012] In a second aspect, the present invention provides a method for preparing a hydrovoltaic device, which includes: preparing a conductive microsphere dispersion and a nanowire layer; coating an indium gallium alloy coating on the bottom surface of the nanowire layer to form a bottom electrode; coating a conductive microsphere dispersion on the top surface of the nanowire layer to deposit the conductive microspheres to form a top electrode.

[0013] In one or more embodiments, the preparation method of the conductive microspheres includes: placing the polymer microspheres in a chemical etching solution for roughening treatment; washing the roughened polymer microspheres and placing them in a sensitizing solution for sensitization treatment; placing the sensitized polymer microspheres in an activation solution for activation treatment; placing the activated polymer microspheres in a chemical plating solution to form a conductive coating on the surface of the polymer microspheres, and centrifuging to obtain the conductive microspheres.

[0014] In one or more embodiments, the chemical etching solution is a mixed solution of potassium dichromate and concentrated sulfuric acid; and / or the sensitizing solution is a mixed solution of concentrated hydrochloric acid and stannous chloride; and / or the activation solution is a mixed solution of palladium chloride and hydrochloric acid; and / or the chemical plating solution is a mixed solution of nickel sulfate, sodium hypophosphite and sodium acetate.

[0015] In one or more embodiments, the preparation method of the conductive microsphere dispersion includes: placing the conductive microspheres in deionized water, and ultrasonically dispersing the conductive microspheres to obtain the conductive microsphere dispersion.

[0016] In one or more embodiments, the preparation method of the nanowire layer includes: immersing an n-type silicon wafer in a seed solution containing silver nitrate and hydrofluoric acid to deposit silver nanoparticles on the surface of the n-type silicon wafer; transferring the n-type silicon wafer with silver nanoparticles deposited on the surface to an etching solution containing hydrogen peroxide and hydrofluoric acid, etching for 30 to 50 minutes, and then immersing it in a nitric acid solution to dissolve residual silver, washing and drying to obtain a nanowire layer.

[0017] Compared with the prior art, the hydrovoltaic device and preparation method provided by the present invention, by using conductive microspheres as the top electrode of the device, can form good electrical contact with the top of the nanowires of the device, efficiently collect the charges in the nanowires, and then conduct the charges out through the connection between the conductive microspheres, which can significantly improve the output performance of the device, thereby promoting its widespread application in the field of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic diagram of an explosion of a water-submerged device in one embodiment of the present invention;

[0020] Figure 2 It is a flow chart of a method for preparing a hydrovoltaic device in one embodiment of the present invention;

[0021] Figure 3 This is an optical image of the polystyrene microspheres before nickel plating under a metallographic microscope in Example 1 of the present invention;

[0022] Figure 4 This is an optical image of the nickel-plated polystyrene microspheres under a metallographic microscope in Example 1 of the present invention;

[0023] Figure 5 is an IV characteristic curve diagram of polystyrene microspheres before and after nickel plating in Example 1 of the present invention;

[0024] Figure 6 This is a test diagram of open circuit voltage of a hydrovoltaic device without conductive microspheres and a hydrovoltaic device coated with conductive microspheres of different diameters in Example 2 of the present invention;

[0025] Figure 7 is a graph showing the relationship between the diameter of the conductive microsphere and the open circuit voltage of the hydrovoltaic device in Example 2 of the present invention;

[0026] Figure 8 This is an open circuit voltage test diagram of a hydrovoltaic device without conductive microspheres and a hydrovoltaic device coated with conductive microspheres with different deposition amounts in Example 2 of the present invention;

[0027] Fig. 9 is a graph showing the relationship between the deposition amount of the conductive microspheres and the open circuit voltage of the hydrovoltaic device in Example 2 of the present invention;

[0028] Fig.10 The hydrovoltaic device without conductive microspheres coated in Example 2 of the present invention and the conductive microspheres coated with conductive microspheres having a diameter of 10 μm and a deposition amount of 2.8 mg / cm 2 The open circuit voltage test diagram of the hydrovoltaic device with conductive microspheres;

[0029] Fig.11 The hydrovoltaic device without conductive microspheres coated in Example 2 of the present invention and the conductive microspheres coated with conductive microspheres having a diameter of 10 μm and a deposition amount of 2.8 mg / cm2 The short-circuit current density test diagram of the hydrovoltaic device with conductive microspheres;

[0030] Fig.12 The hydrovoltaic device without conductive microspheres coated in Example 2 of the present invention and the conductive microspheres coated with conductive microspheres having a diameter of 10 μm and a deposition amount of 2.8 mg / cm 2 The relationship between the output power density of the conductive microsphere hydrovoltaic device and the load resistance. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely 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 should fall within the scope of protection of the present invention.

[0032] It should be noted that, unless otherwise indicated, all numbers used in the specification and claims to represent feature sizes, quantities and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the attached claims are approximate values, and those skilled in the art can use the teachings disclosed herein to seek to obtain the desired properties and appropriately change these approximate values. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.2, 1.4, 1.55, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0033] In the research and application of hydrovoltaic effect, silicon nanowire array hydrovoltaic power generation devices have attracted much attention because of their ability to convert the microscopic movement of water into electrical energy. However, there is a key contradiction in the design of the top electrode in the existing technology: how to ensure efficient electrical contact with the nanowire layer without hindering water evaporation. The existing top electrode is usually covered on the top of the nanowire layer, which to some extent limits the efficiency of water evaporation, thereby affecting the overall performance of the hydrovoltaic device.

[0034] The present invention is derived from an in-depth analysis of the limitations of the top electrode design of existing hydrovoltaic power generation devices. The inventors realize that in order to improve the charge collection efficiency of the device, the top electrode needs to form electrical contact with as many nanowires as possible; at the same time, in order to maintain the water evaporation efficiency, the design of the top electrode should not excessively hinder the evaporation process of water molecules.

[0035] In response to the above technical problems, the present invention proposes a high-performance nanowire hydrovoltaic power generation device based on conductive microsphere electrodes, which aims to improve the charge collection efficiency, enhance the performance of electrode materials, and ensure the water evaporation efficiency, thereby improving the overall output performance of the device.

[0036] The technical implementation ideas of the invention mainly include: using conductive microspheres as top electrodes, forming good electrical contact through multi-point contact between the conductive microspheres and nanowires, and significantly improving the charge collection efficiency; forming conductive channels between the conductive microspheres to provide an efficient charge transfer path, reducing energy loss during charge transfer, and thus optimizing the charge transfer path; utilizing the naturally formed pores between the conductive microspheres to provide channels for the evaporation of water molecules, thereby reducing the obstruction of the top electrode to water evaporation.

[0037] The hydrovoltaic power generation device of the present invention can maintain high efficiency of water evaporation while ensuring efficient electrical contact, thereby resolving the contradictions in the prior art and significantly improving the performance of the hydrovoltaic device. This idea provides a new design direction for the development of hydrovoltaic power generation technology and is expected to promote its widespread application in the field of renewable energy.

[0038] Please refer to Figure 1 As shown, a silicon nanowire hydrovoltaic device provided in one embodiment of the present invention comprises a nanowire layer, a top electrode disposed on the top of the nanowire layer, and a bottom electrode disposed on the bottom of the nanowire layer. The top electrode comprises conductive microspheres distributed on the top of the nanowire layer, and the conductive microspheres are in electrical contact with the top of the nanowire layer to conduct the nanowires in the nanowire layer.

[0039] The nanowire layer is a key functional layer in the hydrovoltaic device of the present invention. Its main function is to capture and collect microscopic mechanical energy in water, such as evaporation, flow or droplet movement, and convert it into electrical energy. Through its surface effect and high specific surface area, the nanowire layer can effectively collect the charges generated by the movement of water molecules to form a double electric layer, thereby generating an electromotive force. When water moves on the surface of the nanowire, it drives the double electric layer on the liquid-solid interface to move, causing positive and negative charges to accumulate in different directions. The nanowire structure can effectively separate and accumulate charges, improving the efficiency of charge collection.

[0040] The nanowire layer includes a substrate and nanowires arranged upright on the substrate. The nanowires can be arranged in an array. The ordered silicon nanowire array can more effectively promote the hydrovoltaic effect. When water evaporates on the surface of the silicon nanowires, the microcirculation caused is more likely to occur along the neatly arranged nanowires, thereby more effectively converting into electrical energy.

[0041] Each silicon nanowire in the silicon nanowire array structure can be regarded as an independent hydroelectric micro-unit. In the ordered array structure, these micro-units can be effectively connected in parallel, thereby improving the power output of the entire device. Orderly arranged silicon nanowires can provide a more regular transmission path for charge carriers, reducing the scattering and loss of electrons during transmission, thereby improving current density and output efficiency.

[0042] The diameter of the nanowire is generally micro-nanoscale. Smaller diameter increases the specific surface area, which is conducive to capturing more mechanical energy. The material of the nanowire is preferably n-type silicon material. Silicon material can be used as the nanowire material in the present invention due to its excellent semiconductor properties and processability. Of course, other semiconductor materials such as zinc oxide (ZnO), titanium oxide (TiO2), etc., can also be used as nanowire materials.

[0043] The top electrode is a conductive material that is in electrical contact with the top of the nanowire layer. Its main function is to collect the electrons generated in the nanowires. Under the hydrovoltaic effect, when water evaporates on the surface of the nanowires to trigger microcirculation, the directional movement of electrons in the nanowires causes current to be generated. The top electrode can effectively collect these electrons, use the electromotive force generated by the nanowire layer, form a circuit, and transmit electrical energy to an external load.

[0044] In the embodiment of the present invention, the conductive microspheres are used as the top electrode to increase the contact points with the nanowires, so that as many nanowires as possible are in electrical contact with the top electrode, which can improve the charge collection efficiency. The pores between the conductive microspheres provide channels for water evaporation, which can reduce the obstacles to water evaporation and enable the hydrovoltaic device to maintain an efficient water evaporation process.

[0045] The diameter of the conductive microspheres is preferably 1 to 100 μm. When the diameter of the conductive microspheres is larger, the contact points with the silicon nanowires can be increased, thereby improving the efficiency of charge collection. However, if the diameter of the microspheres is too large, the spacing between the microspheres may increase, reducing the number of effective contact points per unit area, so it is necessary to find a balance between increasing the contact area and maintaining a sufficient contact point density.

[0046] The working principle of hydrovoltaic devices relies on the evaporation of water molecules on the surface of the nanowire layer. The pores formed between the conductive microspheres provide evaporation channels for water molecules. If the diameter of the microspheres is too small, the pores may be too small, thereby hindering the evaporation of water molecules and reducing the hydrovoltaic effect. On the contrary, appropriately increasing the diameter of the microspheres can provide enough space for water molecules to evaporate while maintaining good electrical contact.

[0047] The distribution amount of the conductive microspheres on the top of the nanowire layer is preferably 0.7 to 3.5 mg / cm 2The distribution amount of the conductive microspheres as the top electrode directly affects the contact area with the silicon nanowires, and thus affects the charge collection efficiency. The appropriate distribution amount can ensure the formation of a good conductive path between the microspheres, while contacting as many nanowires as possible, maximizing the charge collection.

[0048] Specifically, after coating a circle of conductive carbon coating on the outer periphery of the top of the nanowire layer, the conductive microspheres may be deposited so that the conductive microspheres cover the conductive carbon coating. The conductive carbon coating may be used to connect to an external circuit. In other embodiments, the conductive carbon coating may not be provided, and the conductive microspheres may be directly deposited on the top of the nanowire layer.

[0049] In an exemplary embodiment, the conductive microspheres include polymer microspheres and a conductive layer coated on the outer surface of the polymer microspheres. The polymer microspheres are preferably made of polystyrene (PS), and the conductive layer is preferably made of nickel.

[0050] Polymer microspheres provide good mechanical stability and processability. They have low density and high strength, and can maintain the morphology and distribution of the microspheres during the preparation process. The outer conductive layer can improve the conductivity of the microspheres, enabling them to collect and transfer charges efficiently. The coating material selection has excellent conductivity and chemical stability, ensuring charge transfer efficiency and long-term reliability.

[0051] Polystyrene, as a common polymer material, has good chemical stability and mechanical properties, is easy to process into microspheres, and has low cost. Nickel is a metal with good electrical conductivity, and its chemical stability and corrosion resistance make it an ideal choice for the conductive layer.

[0052] In other embodiments, the conductive microspheres may also be made of other materials, such as gold, silver, copper, aluminum, and alloys thereof.

[0053] The bottom electrode is a conductive material that makes electrical contact with the bottom of the nanowire layer, acting as a reference point or counterpoint in the circuit, providing the necessary charge balance. The bottom electrode works with the top electrode to ensure that electrons can be efficiently collected from the nanowires and transferred to the external circuit. The bottom electrode can also provide mechanical support and protection for the nanowire layer, ensuring the structural stability and durability of the device.

[0054] Specifically, a copper substrate electrically contacting the bottom electrode may be provided at the bottom of the bottom electrode, and the copper substrate may be used to connect to an external circuit.

[0055] Please refer to Figure 2 As shown, in one embodiment of the present invention, a method for preparing the aforementioned hydrovoltaic device is also provided, and the preparation method specifically comprises the following steps:

[0056] S201: preparing a conductive microsphere dispersion and a nanowire layer.

[0057] In an exemplary embodiment, the preparation method of the conductive microspheres specifically includes: placing the polymer microspheres in a chemical etching solution for roughening treatment; washing the roughened polymer microspheres and placing them in a sensitizing solution for sensitization treatment; placing the sensitized polymer microspheres in an activation solution for activation treatment; placing the activated polymer microspheres in a chemical plating solution to form a conductive coating on the surface of the polymer microspheres, and centrifuging to obtain the conductive microspheres.

[0058] The roughening treatment specifically includes: placing the polymer microspheres (such as polystyrene microspheres) in a chemical etching solution, usually a mixed solution of potassium dichromate and concentrated sulfuric acid, and reacting for a certain period of time. The roughening treatment can increase the roughness and active sites on the surface of the polymer microspheres to facilitate subsequent sensitization and activation treatments. The surface of the microspheres after the roughening treatment becomes rougher, increasing the specific surface area, which helps to improve the contact efficiency between the microspheres and the subsequent treatment solution, laying the foundation for the formation of a uniform conductive layer.

[0059] The sensitization treatment specifically includes: placing the roughened and cleaned polymer microspheres in a sensitizing solution (such as a mixed solution of concentrated hydrochloric acid and stannous chloride) for treatment. The purpose of the sensitization treatment is to allow a layer of sensitizer to be adsorbed on the surface of the microspheres in preparation for the next activation treatment. A layer of stannous ions is formed on the surface of the sensitized microspheres, which can serve as a catalytic center for the subsequent activation treatment and help the reduction and deposition of metal ions in the chemical plating solution on the surface of the microspheres.

[0060] The activation treatment specifically includes: placing the sensitized microspheres in an activation solution (such as a mixed solution of palladium chloride and hydrochloric acid) containing an activator (such as palladium chloride) for treatment, and heating is usually required to accelerate the reaction rate. The activation treatment is to form catalytic active centers on the surface of the microspheres to ensure that the metal in the chemical plating solution can be reduced on the surface of the microspheres. Catalytic active centers are formed on the surface of the microspheres after the activation treatment. These centers play a catalytic role in the chemical plating process, promote the reduction of metal ions to metal atoms, and form a conductive coating on the surface of the microspheres.

[0061] The formation of the conductive layer by chemical plating specifically includes: placing the activated microspheres in a chemical plating solution, which usually contains a metal salt (such as nickel sulfate), a reducing agent (such as sodium hypophosphite) and a chelating agent (such as sodium acetate). The purpose of chemical plating is to use a reducing agent to reduce metal ions to metal atoms and form a uniform conductive metal layer on the surface of the microspheres. The chemical plating process forms a uniform layer of metal nickel on the surface of the microspheres. This metal layer gives the originally insulating polymer microspheres conductivity, allowing them to be used as conductive microspheres in hydrovoltaic devices.

[0062] In an exemplary embodiment, the preparation method of the conductive microsphere dispersion specifically includes: placing the conductive microspheres in deionized water, and ultrasonically dispersing the conductive microspheres to obtain the conductive microsphere dispersion. The ultrasonic dispersion technology can make the conductive microspheres evenly dispersed in the deionized water to avoid agglomeration and sedimentation of the microspheres.

[0063] Specifically, the weighed conductive microspheres can be added into an ultrasonic cleaning tank filled with deionized water, and appropriate ultrasonic power and time are set, usually the ultrasonic power is tens to hundreds of watts, and the ultrasonic time is a few minutes to tens of minutes.

[0064] In an exemplary embodiment, the nanowire layer is prepared by a metal assisted chemical etching (MACE) method, which specifically includes: immersing an n-type silicon wafer in a seed solution containing silver nitrate and hydrofluoric acid to deposit silver nanoparticles on the surface of the n-type silicon wafer; transferring the n-type silicon wafer with silver nanoparticles deposited on the surface to an etching solution containing hydrogen peroxide and hydrofluoric acid, etching for 30 to 50 minutes, and then immersing it in a nitric acid solution to dissolve residual silver, washing and drying, to obtain an n-type silicon nanowire layer.

[0065] It should be noted that during the etching process, due to the formation of tiny galvanic cells, silicon is preferentially etched at the Si-Ag interface. In this etching process, the silver particles act as a catalyst.

[0066] S202: coating an indium gallium alloy coating on the bottom surface of the nanowire layer to form a bottom electrode.

[0067] S203: coating a conductive microsphere dispersion on the top surface of the nanowire layer to deposit the conductive microspheres to form a top electrode.

[0068] It should be noted that the conductive microsphere dispersion can be evenly coated on the top surface of the nanowire layer by spin coating, spray coating, dipping or drop coating. After coating, the device is placed in a suitable environment (such as an oven or room temperature) to promote solvent evaporation, so that the conductive microspheres are deposited on the nanowire layer to form a uniform, conductive top electrode on the top surface of the nanowire layer.

[0069] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0070] Example 1: Preparation of Conductive Microsphere Dispersion

[0071] Prepare four different diameters of polystyrene microspheres: 1 μm, 3 μm, 5 μm and 10 μm, and then perform nickel plating on the polystyrene microspheres. The nickel plating process and parameters for polystyrene microspheres with different diameters are the same. The specific nickel plating process is as follows:

[0072] (1) Roughening treatment: First, take 8.0g potassium dichromate (K2Cr2O7) and 14mL concentrated sulfuric acid (H2SO4) to prepare 50mL chemical etching solution and heat it in a water bath to 50°C. Then weigh 1.0g polystyrene microspheres, add them to 2mL deionized water and ultrasonically disperse them for 2min. The dispersed polystyrene microspheres are added to the chemical etching solution for roughening reaction for 5min. After roughening, the roughness and contact area of ​​the microsphere surface are increased, and the hydrophilicity is stronger. After roughening, dilute it three times with deionized water and wash and centrifuge it several times until the residual etching solution is completely removed.

[0073] (2) Sensitization: Measure 5 mL of concentrated hydrochloric acid (HCl) and place it in a beaker. Weigh 2.0 g of stannous chloride (SnCl2) and add it to the hydrochloric acid to completely dissolve it. Add deionized water to prepare 50 mL of sensitization solution. Add the roughened microspheres to the sensitization solution, react at room temperature for 10 minutes, and then centrifuge. After sensitization, a layer of stannous ions will be adsorbed on the surface of the microspheres.

[0074] (3) Activation: 5 mL of HCl was measured and placed in a beaker. 25.0 mg of palladium chloride (PdCl2) was weighed and placed in the hydrochloric acid. After it was completely dissolved, deionized water was added to prepare 50 mL of activation solution. The solution was heated to 50°C with magnetic stirring for later use. The sensitized microspheres were added to the activation solution for reaction for 20 min and centrifuged for later use.

[0075] (4) Chemical nickel plating: Weigh 6.0 g of nickel sulfate (NiSO4·6H2O), 4.0 g of sodium hypophosphite (NaH2PO2) and 3.0 g of sodium acetate (Na3C6H5O7·2H2O) respectively, place the three chemicals in a beaker, add deionized water to prepare 50 mL of chemical plating solution and heat to 55°C with magnetic stirring, add the activated microspheres to the solution and react for 25 min, and finally centrifuge to obtain nickel-plated polystyrene microspheres (i.e., conductive microspheres).

[0076] Nickel-plated microspheres with four diameters of 1 μm, 3 μm, 5 μm and 10 μm prepared by chemical nickel plating were dried at 35° C. Deionized water was used as a dispersion liquid to prepare a mixed solution with a concentration of 2 mg / mL for the four nickel-plated microspheres with different diameters.

[0077] Dried nickel-plated microspheres of 10 μm were prepared into dispersions at the following concentrations: 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, and 10 mg / mL, and uniformly dispersed by ultrasonication for later use.

[0078] Please refer to Figure 3 The optical image of the polystyrene microspheres before nickel plating in Example 1 under a metallographic microscope is shown in FIG. Figure 4, which is an optical image of the nickel-plated polystyrene microspheres under a metallographic microscope in Example 1. Figure 3 and Figure 4 It can be seen that the color of the microspheres changes significantly after nickel plating in the manner of Example 1. The color of the microspheres not plated with nickel is relatively dull, while the microspheres plated with nickel have a metallic luster under a metallographic microscope, indicating that the surface of the polystyrene microspheres is successfully coated with a nickel metal layer.

[0079] Please refer to Figure 5 , which is a graph showing the IV characteristic curve of polystyrene microspheres before and after nickel plating in Example 1. Figure 5 It can be seen that the microspheres without nickel plating have basically no conductivity, while the resistance of the microspheres after chemical nickel plating is reduced to the order of tens of kilo-ohms, and their IV characteristic curves are linear, indicating that the polystyrene microspheres after chemical nickel plating have good conductivity, and also proves that the metal nickel layer is successfully plated on the surface of the polystyrene microspheres.

[0080] Example 2: Preparation of hydrovoltaic device

[0081] Prepare a silicon wafer with a thickness of 500 μm, single-sided polishing, a resistivity of 0.01 to 0.05 Ω·cm, and an n-type (100) orientation. Cut the silicon wafer into multiple silicon wafer pieces of 2×2 square centimeters by laser (laser equipment model: Hanhonglaser, TH-UVLMS5, wavelength 350 nanometers, power 20W). Subsequently, the cut silicon wafer pieces are placed in acetone, ethanol and deionized water for ultrasonic cleaning in turn, and each solution is cleaned for 20 minutes. After cleaning, the silicon wafer pieces are blown dry in a nitrogen stream.

[0082] The silicon wafer was immersed in a seed solution containing 0.05M AgNO3 and 4.8M HF for 10 seconds to deposit silver nanoparticles on the surface of the silicon wafer. Subsequently, the silicon wafer was transferred to an etching solution containing 0.3M H2O2 and 4.8M HF, and after etching in the etching solution for 40 minutes, it was immersed in a HNO3 solution to dissolve the residual silver, and then rinsed with deionized water for 5 minutes, and then dried with a nitrogen flow to obtain an n-type silicon nanowire layer.

[0083] The bottom surface of the n-type silicon nanowire layer is coated with an indium gallium alloy coating to form a bottom electrode, which is then connected to a copper substrate. The outer periphery of the top surface of the n-type silicon nanowire layer is coated with a conductive carbon coating to form a top electrode, which is then connected to the top electrode with a copper wire to produce a hydrovoltaic device without conductive microspheres.

[0084] In order to accurately study the effect of depositing conductive microspheres of different diameters on the performance of hydrovoltaic devices and eliminate the impact of differences between different devices on the performance, in Example 2, conductive microsphere dispersions with different diameters (1 μm, 3 μm, 5 μm, 10 μm) and the same concentration (2 mg / mL) prepared in Example 1 were used to deposit the same mass of conductive microspheres on the same device to explore the effect of conductive microspheres of different diameters as top electrodes on the output performance of the device.

[0085] Taking the test steps of the device based on the electrode of 1μm nickel-plated microspheres as an example, 500μL of nickel-plated microspheres (diameter 1μm) with a concentration of 2mg / mL are dripped on the top surface of the silicon nanowire layer of the hydrovoltaic device. Due to the presence of the surface metal nickel layer, the density of the nickel-plated microspheres is greater than the density of water. The nickel-plated microspheres will settle quickly when standing and cover the top of the silicon nanowire array to form a nickel-plated polystyrene microsphere top electrode layer. The test starts after the nickel-plated microspheres are completely settled. The test time for open circuit voltage and short circuit current density is 400s. After the test, the nickel-plated microspheres on the surface of the device are removed with deionized water. Repeat the same test method to test devices based on nickel-plated microsphere top electrodes of other diameters.

[0086] Please refer to Figure 3 The figure shows the open circuit voltage test diagram of the hydrovoltaic device without conductive microspheres and the hydrovoltaic device with conductive microspheres of different diameters. Figure 3 It can be seen that when nickel-plated microspheres are not used ( Figure 3 In the medium W / O), the open circuit voltage of the hydrovoltaic device is the smallest. After using nickel-plated microspheres as the top electrode material, the open circuit voltage of the device is improved, and the open circuit voltage of the device gradually increases with the increase of the diameter of the nickel-plated microspheres.

[0087] Please refer to Figure 4 The figure shows the relationship between the diameter of the conductive microsphere and the open circuit voltage of the hydrovoltaic device. Figure 4 It can be seen that the open circuit voltage of the hydrovoltaic device gradually increased from 560mV measured without using nickel-plated microspheres to 710mV when using nickel-plated microspheres with a diameter of 10μm as the top electrode, and the open circuit voltage increased by 27%. Among the nickel-plated microspheres with different diameters, the nickel-plated microspheres with a diameter of 10μm have the best effect on improving the open circuit voltage of the device. This is because as the diameter of the microsphere increases, the area of ​​the lower surface of the nickel-plated microsphere tends to be flat, which makes it easier to form contact with more silicon nanowire tops, so that the top electrode collects better charges and the device shows a better hydrovoltaic effect.

[0088] In order to accurately study the effect of different deposition amounts of conductive microspheres on the performance of hydrovoltaic devices and eliminate the effect of differences between different devices on the performance, this example uses a conductive microsphere dispersion with the same diameter (10 μm) and different concentrations (2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL) prepared in Example 1 to deposit conductive microspheres of the same diameter on the same device to explore the effect of different deposition amounts of conductive microspheres as top electrodes on the output performance of the device.

[0089] Taking the test steps of the device based on the electrode of 10μm nickel-plated microspheres as an example, 500μL of nickel-plated microspheres with a concentration of 2mg / mL are dripped on the top surface of the silicon nanowire layer of the hydrovoltaic device. Due to the presence of the surface metal nickel layer, the density of the nickel-plated microspheres is greater than the density of water. The nickel-plated microspheres will settle quickly when standing and cover the top of the silicon nanowire array to form a nickel-plated polystyrene microsphere top electrode layer. The test starts after the nickel-plated microspheres are completely settled. The test time for the open circuit voltage and short-circuit current density is 400s. After the test, the nickel-plated microspheres on the surface of the device are removed with deionized water. Repeat the same test method to test devices based on nickel-plated microsphere top electrodes of other concentrations.

[0090] Please refer to Figure 5 The figure shows the open circuit voltage test diagram of the hydrovoltaic device without conductive microspheres and the hydrovoltaic device with conductive microspheres with different deposition amounts. Figure 5 It can be seen that the open circuit voltage of the devices using nickel-plated microspheres with different deposition amounts as the top electrode is greater than that of the devices not using nickel-plated microspheres as the top electrode. And as the deposition amount of nickel-plated microspheres increases, the open circuit voltage tends to gradually increase.

[0091] Please refer to Figure 6 The figure shows the relationship between the deposition amount of conductive microspheres and the open circuit voltage of the hydrovoltaic device. Figure 6 It can be seen that with the continuous increase in the amount of nickel-plated microspheres deposited, the open circuit voltage of the hydrovoltaic device continues to increase, and the open circuit voltage gradually increases from 670mV when no nickel-plated microspheres are added to the deposition amount of nickel-plated microspheres of 2.8mg / cm 2 The device open circuit voltage is 780mV when the device is charged, and the device open circuit voltage is improved by 16.4%. This is because the nickel-plated microspheres with a low deposition amount are distributed on the surface of the nickel-plated microspheres, making it difficult to cover the entire surface of the silicon nanowire array, and the inability to form a continuous film will also affect the charge transfer and collection between the microspheres. As the deposition amount of nickel-plated microspheres increases, the nickel-plated microspheres on the surface of the silicon nanowire array gradually cover the entire surface of the silicon nanowire array, so that more charge accumulation generated by the silicon nanowires can be collected by the nickel-plated microspheres. In addition, the contact between the nickel-plated microspheres will also become better, which makes the open circuit voltage of the device gradually improve with the increase in the deposition amount of the microspheres.

[0092] When the deposition amount is from 2.8 mg / cm 2 Further increase to 3.5 mg / cm 2 When the amount of nickel-plated microspheres increases, the open circuit voltage of the device remains unchanged. This is because the microspheres have covered the surface of the silicon nanowire array and almost all the microspheres have accumulated to form an effective conductive path. Further increasing the amount of microspheres deposited cannot further promote charge collection and transport. This result shows that within a certain range, as the amount of nickel-plated microspheres deposited increases, the hydrovoltaic effect of the silicon-based hydrovoltaic power generation device gradually increases. When the amount of nickel-plated microspheres deposited reaches 2.8 mg / cm 2 When the device was charged, it produced an open circuit voltage of 780mV, and the device achieved the best hydrovoltaic effect.

[0093] In order to further study the effect of nickel-plated polystyrene microspheres as top electrodes on the output performance of nanowire array hydrovoltaic devices, such as output voltage, output current, and output power density, nickel-plated polystyrene microspheres with a diameter of 10 μm were used at a concentration of 2.8 mg / cm 2 The deposition amount is made into the top electrode of the hydrovoltaic device, and relevant performance tests are carried out.

[0094] Please refer to Figure 7 and Figure 8 The following are the hydrovoltaic devices without conductive microspheres and the devices with conductive microspheres with a diameter of 10 μm and a deposition amount of 2.8 mg / cm 2 The open circuit voltage and short circuit current density test diagram of the hydrovoltaic device with conductive microspheres. Figure 7 and Figure 8 It can be seen that after using nickel-plated polystyrene microspheres as the top electrode, the open circuit voltage of the device increased from 650mV without nickel-plated microspheres to 740mV, an increase of 13.8%; the short-circuit current density of the device increased from 27.2μA / cm 2 Increased to 37.5μA / cm 2 , an increase of 37.8%.

[0095] Please refer to Fig. 9 The following are the hydrovoltaic devices without conductive microspheres and the coated conductive microspheres with a diameter of 10 μm and a deposition amount of 2.8 mg / cm 2 The relationship between the output power density of the hydrovoltaic device and the load resistance. Fig. 9 It can be seen that the output power density of the device increases first and then decreases with the increase of the external load resistance. When the external load resistance is equal to the internal resistance of the device, the device has the maximum output power density. The output power density of the hydrovoltaic power generation device with nickel-plated microspheres as the top electrode and the hydrovoltaic power generation device without nickel-plated microspheres as the top electrode has basically the same trend with the change of the external load resistance. Both reach their respective maximum output power when the load resistance value is 10kΩ, which indicates that the deposition of nickel-plated microspheres has little effect on the internal resistance of the hydrovoltaic power generation device.

[0096] In addition, the output power density of the two devices was compared. It was found that the output power density of the device using nickel-plated microspheres as the top electrode was always greater than that of the device not using nickel-plated microspheres as the top electrode. When the load resistance value was 10 kΩ, the maximum output power density of the device could be increased from 8.2 μW / cm 2 Increased to 12.2μW / cm 2 The above test results show that the use of conductive microspheres as the top electrode material of the device can significantly optimize the output performance of the nanowire hydrovoltaic device, and the output power density of the device is also greatly improved.

[0097] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0098] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A hydroelectric device, characterized in that: include: A nanowire layer, a top electrode disposed on the top of the nanowire layer, and a bottom electrode disposed on the bottom of the nanowire layer; The top electrode includes conductive microspheres distributed on the top of the nanowire layer, and the conductive microspheres are in electrical contact with the top of the nanowire layer to conduct the nanowires in the nanowire layer.

2. The hydroelectric device according to claim 1, characterized in that: The diameter of the conductive microsphere is 1 to 100 μm.

3. The hydroelectric device according to claim 1, characterized in that: The distribution amount of the conductive microspheres on the top of the nanowire layer is 0.1 to 100 mg / cm 2 .

4. The hydroelectric device according to claim 1, characterized in that: The conductive microspheres include polymer microspheres and a conductive layer coated on the outer surface of the polymer microspheres. The material of the polymer microspheres includes polystyrene, and the material of the conductive layer includes nickel.

5. The hydroelectric device according to claim 1, characterized in that: The top of the nanowire layer is coated with a conductive coating, and the conductive microspheres cover the conductive coating.

6. A method for preparing a hydrovoltaic device, characterized in that: include: preparing a conductive microsphere dispersion and a nanowire layer; Coating an indium gallium alloy coating on the bottom surface of the nanowire layer to form a bottom electrode; A conductive microsphere dispersion is coated on the top surface of the nanowire layer to deposit the conductive microspheres to form a top electrode.

7. The method for preparing a hydrovoltaic device according to claim 6, characterized in that: The preparation method of the conductive microspheres comprises: placing the polymer microspheres in a chemical etching solution for roughening; After the roughened polymer microspheres are washed, they are placed in a sensitizing solution for sensitization treatment; The sensitized polymer microspheres are placed in an activation solution for activation treatment; The activated polymer microspheres are placed in a chemical plating solution to form a conductive coating on the surface of the polymer microspheres, and then centrifuged to obtain conductive microspheres.

8. The method for preparing a hydrovoltaic device according to claim 7, characterized in that: The chemical etching solution is a mixed solution of potassium dichromate and concentrated sulfuric acid; And / or the sensitizing solution is a mixed solution of concentrated hydrochloric acid and stannous chloride; And / or the activation solution is a mixed solution of palladium chloride and hydrochloric acid; And / or the chemical plating solution is a mixed solution of nickel sulfate, sodium hypophosphite and sodium acetate.

9. The method for preparing a hydrovoltaic device according to claim 6, characterized in that: The preparation method of the conductive microsphere dispersion comprises: The conductive microspheres are placed in deionized water and ultrasonically dispersed to obtain a conductive microsphere dispersion.

10. The method for preparing a hydrovoltaic device according to claim 6, characterized in that: The preparation method of the nanowire layer comprises: The n-type silicon wafer is immersed in a seed solution containing silver nitrate and hydrofluoric acid to deposit silver nanoparticles on the surface of the n-type silicon wafer; The n-type silicon wafer with silver nanoparticles deposited on the surface is transferred to an etching solution containing hydrogen peroxide and hydrofluoric acid, and after etching for 30 to 50 minutes, it is immersed in a nitric acid solution to dissolve the residual silver, washed and dried to obtain a nanowire layer.

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