Dynamic diode based on water evaporation and preparation method thereof

Abstract

The invention belongs to the technical field of green renewable energy sources, and discloses a dynamic diode based on water evaporation and a preparation method thereof. The generator comprises a first electrode, a semiconductor layer, a liquid layer, an evaporation layer and a second electrode, and environment heat energy is efficiently converted into electric energy through the synergistic effect of dynamic movement of a three-phase line in the liquid evaporation process, a built-in electric field of a semiconductor heterojunction and dynamic depolarization of liquid molecules. The liquid layer uses polarized liquid such as water, the semiconductor layer and an evaporation layer material form a heterojunction, and a strong built-in electric field (up to 7 * 1010V / cm) of polarized molecules such as water molecules is utilized to overturn and drive directional migration of carriers. The evaporation layer regulates and controls the dynamic behavior of a liquid film through the capillary action, and multi-stage energy conversion is achieved in combination with the electric charge density gradient change of the double electric layers. The invention has high environmental adaptability, can work in the environment with the humidity of 30-90% and the temperature of 10-50 DEG C, obviously improves the output power (the open-circuit voltage reaches 0.37 V, and the short-circuit current density is 600nA / cm < 2 >), and has high efficiency and industrialization potential.

Description

Technical Field

[0001] This invention belongs to the field of novel green and renewable energy acquisition, and particularly relates to a dynamic diode based on water evaporation and its preparation method. Background Technology

[0002] Exploring and developing technologies for the collection and conversion of clean energy is a crucial issue in addressing growing energy demand and achieving carbon neutrality. On the other hand, traditional Faraday generators are unsuitable for powering today's rapidly evolving small, portable devices. Therefore, there is a strong push to develop new types of generators capable of converting clean energy sources such as solar, wind, and tidal power into electricity.

[0003] Since carbon nanotubes in flowing liquids were widely shown to generate voltage in 2001, the application of new carbon nanomaterials to the generation of clean energy has attracted widespread attention.

[0004] Since its discovery, graphene has attracted widespread attention due to its unique structure and excellent chemical and physical properties. In particular, as a flexible, transparent conductive material with excellent electrical conductivity, it has demonstrated strong competitiveness in transparent conductive thin-film devices, sensors, and new energy fields, leading to its widespread application. Existing water evaporation power generation technologies mostly rely on a single energy conversion mechanism (such as the water photovoltaic effect or triboelectric nanogenerator), which suffers from drawbacks such as low output power and poor environmental adaptability. While traditional graphene-piezoelectric composite structures can generate electricity through water flow-induced strain, they are limited by the instability of water flow energy and do not fully utilize the built-in electric field of the heterojunction to regulate carrier transport. Furthermore, the insufficient interfacial coupling efficiency between graphene and piezoelectric materials in existing technologies limits energy conversion efficiency. Summary of the Invention

[0005] The core objective of this invention is to overcome the technical bottlenecks of traditional water evaporation power generation technology, such as a single energy conversion mechanism, limited output power, and insufficient environmental adaptability. It proposes a water evaporation nanogenerator based on the synergistic effect of a semiconductor heterojunction and a dynamic double layer. By utilizing the coupling effect of the built-in electric field reversal of liquid molecules and the charge separation of the double layer induced by water evaporation, the efficient conversion of environmental thermal energy into electrical energy is achieved. Simultaneously, the precise control of the dynamic behavior of the liquid film by the evaporation layer enhances the output stability and energy conversion efficiency of the device.

[0006] This invention discloses a dynamic diode based on water evaporation, comprising: a semiconductor layer, a liquid layer, and an evaporation layer; and a first electrode and a second electrode respectively disposed on the semiconductor layer and the evaporation layer. In the entire device, the upper surface of the first electrode is tightly bonded to the lower surface of the semiconductor layer, the semiconductor layer is tightly bonded to the liquid layer, and the liquid layer is covered by the evaporation layer. The evaporation layer is a single-layer graphene / PET film or a porous film (such as a porous carbon film or carbon nanotube paper). When the evaporation layer is a single-layer graphene / PET film, its graphene surface is in contact with the liquid layer, and the second electrode is connected to the graphene. The generator continuously generates current through the evaporation of the liquid between the evaporation layer and the semiconductor layer, converting environmental heat energy into electrical energy.

[0007] The first and second electrodes are independently selected from one or more composite electrodes made of gold, palladium, nickel, titanium, chromium, silver, platinum and aluminum, and the thickness is preferably 50-300 nm.

[0008] The semiconductor layer is selected from one of the following semiconductors: silicon, gallium arsenide, indium gallium arsenide, zinc oxide, germanium, cadmium telluride, gallium nitride, indium phosphide, silicon carbide, molybdenum disulfide, black phosphorus, tungsten diselenide, molybdenum distelluride, and tungsten disulfide.

[0009] The liquid in the liquid layer is a polar liquid, including but not limited to deionized liquids.

[0010] In addition, the dynamic diode also includes a detection device, such as a Keithley 6514 electrometer or other instrument suitable for current measurement.

[0011] The technical solution of this invention specifically includes the following innovative designs: 1) Semiconductor heterostructure construction The presence of polar liquid promotes the formation of a heterojunction structure between the semiconductor layer and the evaporation layer, utilizing the strong built-in electric field (up to 10⁻⁶) of polar molecules such as water molecules. 10 The V / cm flip-driven charge carrier directional migration is achieved. This electric field, acting as the driving force for the directional migration of charge carriers, significantly reduces the probability of charge recombination, ensuring efficient separation of electron-hole pairs under evaporation-driven conditions. 2) Dynamic double-layer modulation mechanism At the interface between the semiconductor layer and the liquid layer, ions in the polarized liquid (such as deionized water) form an electric double layer (approximately 1-10 nm thick) under the influence of the semiconductor surface potential. As water continues to evaporate, the triplet line (solid-liquid-gas interface) between the semiconductor layer and the evaporation layer continuously shifts, leading to a change in the charge density gradient of the electric double layer (Δσ can reach 10^-3 C / m). 2 This dynamic process directly modulates the depletion layer width of the semiconductor Schottky junction through the field effect (with variations ranging from 20% to 50%), thereby periodically releasing the stored interface charge; 3) Device structure optimization Metal electrodes are symmetrically distributed on both sides of the semiconductor layer, and interface losses are reduced through work function matching (e.g., the contact barrier between the gold electrode and silicon is <0.1eV). When a single-layer graphene / PET composite structure is selected for the evaporation layer (transmittance >85%), its surface functional groups (-OH, -COOH) can enhance the adhesion of the liquid film, so that the three-phase line movement rate is synchronized with the evaporation rate.

[0012] The beneficial effects of this invention compared to the prior art are: This invention achieves multiple technological breakthroughs through the synergistic effect of semiconductor heterojunctions, dynamic electric double layers, and porous evaporation layers: First, the energy conversion efficiency is improved compared to traditional water-based photovoltaic technology due to the coupling effect of the built-in electric field reversal of liquid molecules and the charge modulation of the electric double layer; Second, environmental adaptability is significantly enhanced, and it can stably output electrical energy within a humidity range of 30-90% and a temperature range of 10-50℃, making it suitable for extreme scenarios such as deserts and oceans; Third, the device supports micro-nano-scale array fabrication, providing a self-powered solution for IoT devices such as micro sensors; Fourth, the use of solution-based heterojunction assembly and roll-to-roll graphene transfer technology combines high efficiency with industrial-scale economic advantages. Attached Figure Description

[0013] Figure 1 This is a schematic cross-sectional view of the layered structure of the device of the present invention; Figure 2 This is a charge distribution model in the device of the present invention; Figure 3 A model for current generation when the three-phase lines move during water evaporation; Figure 4 Experimental data on the voltage output of the device in Embodiment 1 of the present invention under different temperature environments; Figure 5 This is a voltage curve generated by the device in Embodiment 1 of the present invention; Figure 6 This is a current curve generated by the device in Embodiment 1 of the present invention; Figure 7 This is a voltage diagram generated by the device in Embodiment 1 of the present invention after 12 hours of continuous operation; Figure 8 This is a graph showing the relationship between the thickness of the liquid layer (3) of the device in Embodiment 1 of the present invention and the output voltage; Figure 9 This is a graph showing the voltage and current comparison experiment of the device in Embodiment 1 of the present invention under different light intensities; Figure 10 Band structure diagram of the device of this invention; Figure 11 A diagram showing the change in the band structure of the device of the present invention during water evaporation; Figure 12 A schematic diagram of the device of this invention. Figure 13 This is a voltage curve generated by the device in Embodiment 2 of the present invention; Figure 14 This is a current curve generated by the device in Embodiment 2 of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] Reference Figure 1 According to a specific embodiment of the present invention, in this example, the dynamic diode based on water evaporation is fabricated by first forming a first electrode 1 on the back side of the semiconductor layer 2; then transferring a monolayer graphene layer onto PET to form a monolayer graphene / PET film, and fabricating a second electrode 5 at the edge to connect with the graphene; subsequently, pressing the graphene side of the monolayer graphene / PET film 4 onto the front side of the semiconductor layer 2, and injecting a small amount of deionized water between the layers, thus obtaining the dynamic diode based on water evaporation. The amount of deionized water is typically sufficient to form a liquid film between the layers.

[0016] In this invention, direct current output can be obtained by utilizing the movement of the solid-liquid-gas three-phase lines and the change in the electric double layer during the evaporation of polar liquids such as water. Taking the above example, this is because when the semiconductor and graphene come into contact with water, such as... Figure 2 , Figure 3 As shown, electrons diffuse from the side with a higher Fermi level to the side with a lower Fermi level. When the water at the three-phase line evaporates, the diffused electrons are bounced back into the external circuit by the built-in electric field of the interface. This is due to the ultrafast carrier separation process at the graphene-semiconductor interface. Compared with traditional electromagnetic induction generators, this generator does not require the addition of large-volume coils and is not limited by the environment, enabling the supply of clean energy to lightweight, miniaturized, and portable devices.

[0017] Example 1 1) Select an N-type silicon wafer (resistivity 0.01Ω·cm, thickness 500μm) as the semiconductor layer (2), and clean it with acetone, ethanol and deionized water in sequence for 10 minutes to remove surface organic contaminants. 2) Soak in hydrofluoric acid solution (5% concentration) for 2 minutes to remove the surface oxide layer and obtain a clean silicon surface; 3) Deposit titanium / gold composite electrodes on the lower surface of silicon wafer by magnetron sputtering (1): first deposit a titanium adhesion layer (10 nm thick), then deposit a gold conductive layer (100 nm thick). 4) Take a piece of polyethylene terephthalate (PET) flexible substrate of appropriate size, and clean the substrate surface in acetone solution and ethanol solution in turn to remove impurities attached to the surface, and then dry it with N2. 5) Select one side of the PET flexible substrate as the front side, transfer a single layer of graphene to the surface of the PET substrate to form a graphene / PET film, and expose part of the graphene on the PET film side for electrode preparation; 6) An electrode is fabricated on the exposed graphene surface of the PET film, using a 50nm silver electrode material; 7) Drop 10 μL of deionized water onto the other side of the N-type silicon wafer after treatment in step 3); 8) The graphene side of the graphene / PET film is brought into close contact with deionized water to form an N-type silicon / deionized water / graphene heterojunction structure. 9) Connect the silver electrode on the graphene to the positive terminal of the ammeter, and connect the gold electrode on the N-type silicon to the negative terminal of the ammeter. 10) Experimental results of the device's voltage output under different temperature conditions are as follows: Figure 4 As shown; in an environment with a temperature of 25℃ and a humidity of 60%, the open-circuit voltage of the device during natural evaporation was measured to be 0.35V. Figure 5 The short-circuit current density is 600 nA / cm². 2 ( Figure 6 ). 11) The voltage output result of the device after 12 hours of operation is as follows: Figure 7 As shown in the figure, the relationship between the distance between the graphene and the silicon wafer and the output voltage is as follows: Figure 8 As shown. 12) In an environment with a temperature of 25℃ and a humidity of 60%, at a power of 10W / m 2 30W / m 2 50W / m 2 The open-circuit voltages measured during the natural evaporation of the device under different light intensities were 0.68V, 0.74V, and 0.75V, respectively. Figure 9 The short-circuit current density is 850 nA / cm². 2 950 nA / cm 2 1050 nA / cm 2 ( Figure 9 ).

[0018] Example 2 1) Select an N-type silicon wafer (resistivity 0.01Ω·cm, thickness 500μm) as the semiconductor layer (2), and clean it with acetone, ethanol and deionized water in sequence for 10 minutes to remove surface organic contaminants. 2) Soak in hydrofluoric acid solution (5% concentration) for 2 minutes to remove the surface oxide layer and obtain a clean silicon surface; 3) Deposit titanium / gold composite electrodes on the lower surface of silicon wafer by magnetron sputtering (1): first deposit a titanium adhesion layer (10 nm thick), then deposit a gold conductive layer (100 nm thick); 4) Disperse carbon nanotubes in a solvent (such as water, ethanol or DMF), sonicate to form a uniform suspension, then deposit carbon nanotubes on the filter membrane by vacuum filtration, dry and peel off to obtain buckypaper as a water evaporation layer (4). 5) Electrodes were fabricated on the surface of carbon nanotube buckypaper, using 50nm silver electrodes; 6) Drop 10 μL of deionized water onto the surface of the N-type silicon wafer after treatment in step 3); 7) By bringing carbon nanotube bacillus paper into close contact with deionized water, an N-type silicon / deionized water / carbon nanotube bacillus paper heterojunction structure is formed. 8) Connect the silver electrode on the carbon nanotube buckypaper to the positive terminal of the ammeter, and connect the gold electrode on the N-type silicon to the negative terminal of the ammeter. 9) In an environment with a temperature of 25℃ and a humidity of 60%, the open-circuit voltage of the device during natural evaporation was measured to be 0.035V. Figure 13 The short-circuit current density is 80 nA / cm². 2 ( Figure 14 ). The embodiments described above are merely some preferred embodiments of the present invention, and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A dynamic diode based on water evaporation, characterized in that, The device includes a first electrode (1), a semiconductor layer (2), a liquid layer (3), an evaporation layer (4), and a second electrode (5). The upper surface of the first electrode (1) is tightly bonded to the lower surface of the semiconductor layer (2). The semiconductor layer (2) is tightly bonded to the liquid layer (3). The liquid layer (3) is covered by the evaporation layer (4). The second electrode (5) is led out from the evaporation layer (4). The generator continuously generates current through the evaporation of the liquid between the evaporation layer (4) and the semiconductor layer (1), converting thermal energy in the environment into electrical energy.

2. The dynamic diode based on water evaporation according to claim 1, characterized in that, The first electrode (1) is a composite alloy electrode material of any one or more of gold, palladium, nickel, titanium, chromium, silver, platinum and aluminum.

3. The dynamic diode based on water evaporation according to claim 1, characterized in that, The semiconductor layer (2) is made of silicon, gallium arsenide, indium gallium arsenide, zinc oxide, germanium, cadmium telluride, gallium nitride, indium phosphide, silicon carbide, molybdenum disulfide, black phosphorus, tungsten diselenide, molybdenum distelluride, molybdenum diselenide or tungsten disulfide.

4. The dynamic diode based on water evaporation according to claim 1, characterized in that, The liquid layer (3) is a polar liquid, which includes, but is not limited to, deionized water.

5. The dynamic diode based on water evaporation according to claim 1, characterized in that, The evaporation layer (4) is a single-layer graphene / PET film or a porous film material, wherein the porous film material is a porous carbon film or carbon nanotube paper.

6. The dynamic diode based on water evaporation according to claim 1, characterized in that, The second electrode (5) is a composite alloy electrode material of any one or more of gold, palladium, nickel, titanium, chromium, silver, platinum and aluminum.

7. A method for preparing a dynamic diode based on water evaporation as described in any one of claims 1-6, characterized in that, The process includes the following steps: fabricating a first electrode on one side of a clean semiconductor layer, fabricating a second electrode on one side of an evaporation layer, placing the other side of the evaporation layer opposite to the other side of the semiconductor layer, injecting a polar liquid between the two to form a liquid film, or using the other side of the semiconductor layer as a liquid storage area, dripping a polar liquid into the liquid storage area, and covering the polar liquid with the other side of the evaporation layer facing down, so that the polar liquid forms a liquid film between the two and fully contacts the semiconductor layer and the evaporation layer.

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