A process for preparing PEDOT:PSS flexible thermoelectric thin films

Abstract

This invention proposes a process for preparing a flexible thermoelectric thin film using PEDOT:PSS, comprising: filtering PEDOT:PSS to remove large particles from an aqueous solution and placing the filtrate in a vacuum chamber to remove air bubbles before use; preparing various cleaning agents and pre-cleaning a quartz glass slide by repeatedly immersing it in the various ionic cleaning agents, and storing the cleaned quartz glass slide in an ethanol solution; drop-casting the filtered PEDOT:PSS onto a quartz glass substrate; immersing the PEDOT:PSS film on the quartz glass substrate in CH3NO at room temperature; and heating to achieve cleaning. After drying the PEDOT:PSS membrane, CH3NO solution is dropped onto the PEDOT:PSS membrane, heated on a hot plate, and then rinsed with deionized water to remove residual CH3NO. The PEDOT:PSS membrane is then dried. The CH3NO-treated PEDOT:PSS membrane is then immersed in concentrated H₂SO₄ at room temperature and rinsed multiple times with deionized water to remove residual H₂SO₄. Finally, it is dried to obtain a flexible PEDOT:PSS thermoelectric film. Thus, this invention has the advantages of impact resistance and free bending, as well as flexibility and bending performance.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric technology, and specifically relates to a process for preparing PEDOT:PSS flexible thermoelectric thin films. Background Technology

[0002] Electricity is an essential resource for people today, and batteries are used in every aspect of our lives. Lithium batteries are the most widely used medium for storing electricity in daily life. However, the batteries used in most products still have many problems, such as: short battery life, inability to use for extended periods; need for repeated charging, resulting in short battery lifespan; heavy batteries, causing serious chemical pollution... Existing commercially available conventional lithium batteries are unable to meet the ever-increasing market demands.

[0003] Currently, the smart wearable device industry is booming, market demand is expanding, and the performance requirements for batteries are also increasing. However, the batteries used in most current products still have many problems. For example, due to unforeseen circumstances, existing batteries may not be able to recharge in time, causing the positioning and alarm functions of smart wearable devices to malfunction. This is particularly disadvantageous for young children, the elderly, and people with cognitive impairments, and also causes great inconvenience to their caregivers. At the same time, existing batteries consume power faster at low temperatures, significantly shortening battery life. Furthermore, existing batteries are relatively heavy, making them inconvenient to carry; and there are serious recycling issues with existing batteries, as most become chemical waste after disposal, negatively impacting the environment. All these problems make it difficult for current batteries to meet the ever-increasing market demands. Summary of the Invention

[0004] This invention proposes a PEDOT:PSS flexible thermoelectric thin film preparation process, which solves the problems in the prior art.

[0005] The technical solution of this invention is implemented as follows: A PEDOT:PSS flexible thermoelectric thin film preparation process includes:

[0006] Filtering PEDOT:PSS removes large particles from the aqueous solution, and placing the filtrate in a vacuum chamber removes air bubbles before use;

[0007] Multiple cleaning agents were prepared, and quartz glass slides were repeatedly immersed in the multiple ionic cleaning agents for pre-cleaning. The cleaned quartz glass slides were then stored in an ethanol solution.

[0008] The filtered PEDOT:PSS was drop-cast onto a quartz glass matrix and dried overnight.

[0009] The PEDOT:PSS membrane on the quartz glass substrate was immersed in CH3NO at room temperature and rinsed with deionized water to remove residual CH3NO from the surface of the PEDOT:PSS membrane.

[0010] Heating to dry the cleaned PEDOT:PSS membrane, dropping CH3NO solution onto the PEDOT:PSS membrane, heating on a hot plate, rinsing with deionized water to remove residual CH3NO, and then drying the PEDOT:PSS membrane.

[0011] The PEDOT:PSS membrane treated with CH3NO was immersed in concentrated H2SO4 at room temperature, then rinsed repeatedly with deionized water to remove residual H2SO4, and then dried.

[0012] PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in different NaBH4 solutions at room temperature for treatment, then rinsed in deionized water to remove residual NaBH4, and then dried to obtain PEDOT:PSS flexible thermoelectric thin films.

[0013] In a preferred embodiment, the PEDOT:PSS flexible thermoelectric film is cut into several pieces, and each piece of the PEDOT:PSS flexible thermoelectric film is placed on a film carrier. Each piece of the PEDOT:PSS flexible thermoelectric film is arranged at an angle, and each piece of the PEDOT:PSS flexible thermoelectric film is connected in series by a wire.

[0014] In a preferred embodiment, the two ends of the PEDOT:PSS flexible thermoelectric film are coated with insulating graphite to insulate the two ends of the PEDOT:PSS flexible thermoelectric film so that they form hot and cold ends.

[0015] In a preferred embodiment, the PEDOT:PSS flexible thermoelectric film is inserted into the ceramic fiber layer in the middle, and the upper and lower insulating graphite layers and the edge of the middle ceramic fiber layer are sealed with adhesive, so that the PEDOT:PSS flexible thermoelectric film forms two temperature cavities.

[0016] In a preferred embodiment, the conductor is a copper conductor with an insulating sheath, and the contact portion between the conductor and the PEDOT:PSS flexible thermoelectric film is sealed with silver paste.

[0017] As a preferred embodiment, prepare multiple containers and rinse them with deionized water, dry them in an oven for 10 minutes, filter PEDOT:PSS using a vacuum-assisted syringe, measure 10 ml of PEDOT:PSS with a graduated cylinder and put it in a beaker, then filter it with a filter to remove large particles from the aqueous solution, put the filtrate in another beaker, and place the filtrate in a vacuum chamber to remove air bubbles before use.

[0018] Prepare 5% detergent, ethanol, deionized water, acetone, isopropanol and plasma cleaner in a fume hood. Then, quartz glass slides are repeatedly immersed in the various cleaners for pre-cleaning. After cleaning, the quartz glass slides are stored in an ethanol solution.

[0019] As a preferred embodiment, the PEDOT:PSS membrane is immersed in CH3NO at room temperature for 10 min, rinsed with deionized water to remove residual CH3NO from the surface, and then heated on a hot plate at 80°C for 10 min to dry it.

[0020] Then, the CH3NO solution was dropped onto the PEDOT:PSS membrane, heated on a hot plate at 160°C for 15 min, rinsed with deionized water to remove residual CH3NO, and dried at 80°C for 10 min.

[0021] The sample treated with CH3NO was immersed in concentrated H2SO4 at room temperature for 10 hours, then rinsed four times with deionized water to remove residual H2SO4, and then dried at 80℃ for 10 minutes.

[0022] The PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in different NaBH4 solutions for 30 min at room temperature, then rinsed four times in deionized water to remove residual NaBH4, and then dried at 80℃ for 30 min.

[0023] In a preferred embodiment, the PEDOT:PSS flexible thermoelectric films connected in series are electrically connected to an energy collection module and a capacitor, respectively.

[0024] After adopting the above technical solution, the beneficial effects of the present invention are:

[0025] The flexible film is obtained by filtering PEDOT:PSS and then casting it onto a silica matrix to obtain a PEDOT:PSS flexible thermoelectric film. The resulting PEDOT:PSS flexible thermoelectric film is then connected in series to form a series circuit to increase the output voltage. Batteries based on PEDOT:PSS flexible thermoelectric films have the significant advantages of good flexibility and thermoelectric power generation, and can be applied in multiple fields. Utilizing the Seebeck effect, this film generates a certain voltage by taking advantage of the temperature difference between the human skin surface and the surrounding environment, thereby extending the battery life. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the thermoelectric power generation component used in this invention;

[0028] Figure 2 This is a flow chart of the PEDOT:PSS flexible thermoelectric thin film preparation process of the present invention;

[0029] Figure 3 It is a complete thin film after separation from the quartz glass matrix;

[0030] Figure 4 The dried film;

[0031] Figure 5 This is a schematic diagram of the PEDOT:PSS flexible thermoelectric thin film connected in series.

[0032] Figure 6 Circuit diagram of the power boost module used for PEDOT: PSS flexible thermoelectric film;

[0033] Figure 7 Schematic diagram of the power boost module used for PEDOT:PSS flexible thermoelectric film;

[0034] Figure 8 A product structure diagram for applying the PEDOT:PSS flexible thermoelectric film of this invention;

[0035] Figure 9 A schematic diagram of the Seebeck effect;

[0036] Figure 10 Voltage line graphs generated for thin films using different manufacturing processes;

[0037] Figure 11 A graph showing the relationship between length and temperature;

[0038] Figure 12 This is a schematic diagram of voltage measurement using substrate A;

[0039] Figure 13 This is a schematic diagram of voltage measurement using substrate B;

[0040] Figure 14 This is a schematic diagram of the series voltage measurement at the critical length and a width of 1.25 mm.

[0041] Figure 15Experimental data graph for the power boost module used in PEDOT:PSS flexible thermoelectric thin film;

[0042] Figure 16 A cross-sectional view of a product using the PEDOT:PSS flexible thermoelectric film of this invention.

[0043] In the figure, 1-PEDOT: PSS flexible thermoelectric film; 2-wire; 3-film carrier; 4-ceramic fiber layer; 5-power boost module; 6-capacitor; 7-silver paste; 8-insulating graphite. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] like Figure 2 As shown, the technical solution of the present invention is implemented as follows: A PEDOT:PSS flexible thermoelectric thin film preparation process includes:

[0046] Filtering PEDOT:PSS removes large particles from the aqueous solution, and placing the filtrate in a vacuum chamber removes air bubbles before use;

[0047] Multiple cleaning agents were prepared, and quartz glass slides were repeatedly immersed in the various ionic cleaning agents for pre-cleaning. The cleaned quartz glass slides were then stored in an ethanol solution for convenient subsequent use.

[0048] The filtered PEDOT:PSS was drop-cast onto a quartz glass matrix and dried overnight.

[0049] The PEDOT:PSS membrane on the quartz glass substrate was immersed in CH3NO at room temperature and rinsed with deionized water to remove residual CH3NO from the surface of the PEDOT:PSS membrane.

[0050] Heating to dry the cleaned PEDOT:PSS membrane, dropping CH3NO solution onto the PEDOT:PSS membrane, heating on a hot plate, rinsing with deionized water to remove residual CH3NO, and drying the PEDOT:PSS membrane at 60°C for 10 min.

[0051] The PEDOT:PSS membrane treated with CH3NO was immersed in concentrated H2SO4 at room temperature, then rinsed repeatedly with deionized water to remove residual H2SO4, and then dried.

[0052] The PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in different NaBH4 solutions at room temperature for treatment, then rinsed in deionized water to remove residual NaBH4, and then dried to obtain PEDOT:PSS flexible thermoelectric thin film 1.

[0053] PEDOT: PSS film is a thermoelectric material. Thermoelectric materials are functional materials that convert heat energy into electrical energy by utilizing the directional flow of charge carriers within the material. The application of thermoelectric materials does not require transmission components, operates without noise or waste, similar to the application of secondary energy sources such as solar, wind, and hydropower. With no moving parts and no waste emissions, it causes no environmental pollution. Furthermore, this material is reliable, produces no noise pollution, and can achieve stable operation for extended periods, making it an environmentally friendly material with broad application prospects.

[0054] like Figure 1 As shown, thermoelectric power generation utilizes the Seebeck effect of thermoelectric materials, which refers to the generation of an electromotive force (EMF) by utilizing the temperature gradient between the two ends of the material to provide electricity to the device. When two conducting materials form a closed circuit, an EMF is generated because the junction of the two materials is at different temperatures, thus inducing a current in the circuit. The greater the temperature difference, the stronger the current. Therefore, as long as there is a temperature gradient between the two materials, electrons will continue to diffuse, thereby forming a stable potential difference and current between the two substances.

[0055] Thermoelectric power generation has a wide range of applications, including engine exhaust heat, human body heat, automotive waste heat, and sensors in low- or high-temperature environments. For space probes, thermoelectric power generation systems based on radioactive isotope heating are currently the only sustainable power supply system. Thermoelectric power generation devices for automotive engines and exhaust systems are also a current research hotspot. Thermoelectric power generation systems that use the human body as a heat source to power watches, headphones, hearing aids, and implantable medical devices have a broad market potential.

[0056] PEDOT:PSS is a high-molecular-weight polymer with high and adjustable conductivity, typically existing in aqueous solution. This conductive polymer material is composed of two substances: PEDOT (a polymer of EDOT, 3,4-ethylenedioxythiophene monomer) and PSS (polystyrene sulfonate). The addition of PSS significantly improves the solubility of PEDOT. The table below shows the basic properties of the PEDOT:PSS material:

[0057] project index Appearance Deep Blue Solid content (%) 1.3-1.7 Resistance (Ω·cm) 500-8000 Viscosity (mPas) 5-15 Particle size distribution d50 (nm) ～80 Particle size distribution d90 (nm) ～100 Work function (eV) 4.8-5.2

[0058] The flexible film is made by filtering PEDOT and then casting it onto a silica matrix. The series circuit increases the output voltage by densely connecting many films in series. The boost module consists of three parts: a power boost module, an intermediate energy storage module, and a power voltage regulator module, which can collect 25mV electromotive force and output a stable 3.3V. Batteries based on PEDOT:PSS flexible thermoelectric films have significant advantages such as good flexibility and thermoelectric power generation. They have applications in various fields, from medical devices like hearing aids, cochlear implants, and pacemakers to everyday devices like Bluetooth headsets and smart bracelets. They can completely replace power supply solutions for other low-power devices or assist in powering high-power devices, extending battery life. Their flexibility and thinness make them ideal for smart wearable devices. Experimental tests show that by utilizing the temperature difference between the human body surface and the external environment, the power density generated by this battery is 1-2 orders of magnitude higher than the best current pure organic thermoelectric film batteries, which has practical significance for the innovation of wearable device power supplies.

[0059] like Figure 5 As shown, the PEDOT:PSS flexible thermoelectric film 1 is cut into several pieces, and each piece of the PEDOT:PSS flexible thermoelectric film 1 is placed on the film carrier 3. Each piece of the PEDOT:PSS flexible thermoelectric film 1 is arranged in an oblique staggered manner, and each piece of the PEDOT:PSS flexible thermoelectric film 1 is connected in series by a wire 2.

[0060] PEDOT: The PSS flexible thermoelectric film 1 possesses excellent flexibility and an extremely thin thickness. To improve power generation efficiency, we employ a dense series connection method to significantly increase the output voltage, thereby raising the upper limit of product performance. Based on the principle that a voltage is generated due to a temperature difference between the two ends of the thermoelectric film, the thermoelectric film is cut into an area of ​​2*25 (mm). Multiple films are arranged on a self-made flexible circuit board, with the films arranged diagonally. The film wires 2 are connected using silver paste 7, which has excellent conductivity and is commonly used in membrane switches, forming a series circuit that greatly improves the area power generation rate of the circuit board.

[0061] A power collection module and a capacitor 6 are electrically connected to the PEDOT:PSS flexible thermoelectric film 1 connected in series.

[0062] like Figure 6 and Figure 7As shown, the power harvesting module consists of three parts: a power boost module 5, an intermediate energy storage module, and a power regulator module. It can harvest a 25mV electromotive force and output a stable 3.3V. When a 25mV input is received, a slightly higher voltage is first output by a charge pump capacitor and a voltage transformer to activate the LTC3108-1 chip. The voltage is amplified by the MOSFETs within the chip, achieving a 3.7V output without changing the power. This voltage is then fed into the supercapacitor in the intermediate energy storage section to store the charge. Storage continues until the voltage across the capacitor reaches 3.7V, at which point it is output to the power regulator module. The power regulator module accepts input voltages from 1.8V to 5.5V and outputs a stable 3.3V. When the capacitor in the intermediate energy storage section outputs voltage, the TPS63900 chip is activated. The combination of MOSFETs within the chip then achieves a stable 3.3V output.

[0063] like Figure 8 and Figure 16 To improve the efficiency of thermoelectric power generation, silver paste 7 is used for a sealed connection at the junction of the thin film and the internal conductor 2 of the flexible circuit board.

[0064] The two ends of the PEDOT:PSS flexible thermoelectric film 1 are coated with insulating graphite 8 to insulate the two ends of the PEDOT:PSS flexible thermoelectric film 1 so that they form hot and cold ends.

[0065] The PEDOT:PSS flexible thermoelectric film 1 is inserted into the ceramic fiber layer 4 in the middle, and the upper and lower insulating graphite layers and the edge of the middle ceramic fiber layer are sealed with adhesive, so that the PEDOT:PSS flexible thermoelectric film 1 forms two temperature cavities.

[0066] The conductor 2 is a copper conductor with an insulating outer sheath, and the contact area between the conductor 2 and the PEDOT:PSS flexible thermoelectric film 1 is sealed with silver paste 7.

[0067] Based on the thermoelectric power generation principle of PEDOT:PSS flexible thermoelectric film, an insulating graphite film 8 is used to cover the film externally, and the two ends of the film are insulated to form a hot and cold end, thus creating two temperature cavities to achieve the effect of thermoelectric power generation. To reduce voltage and current loss, the film is interspersed in the ceramic fiber layer 4 internally, forming two temperature cavities inside the battery to reduce heat exchange within the battery. At the same time, the film is connected to the energy collection module and capacitor 6 through wires 2. The boost module in the collection module raises the electromotive force generated by the film to the volt level and pours it into capacitor 6 for storage. After capacitor 6 stores a certain amount of energy, a voltage regulator ensures a stable current output.

[0068] like Figures 3-4As shown, prepare 8 clean beakers in advance. Rinse the beakers with deionized water and dry them in an oven for 10 minutes. Filter PEDOT:PSS (Clevios PH 1000) using a vacuum-assisted syringe filter. Measure 10 ml of PEDOT into a beaker using a graduated cylinder and then filter it to remove large particles from the aqueous solution. Place the filtrate in another beaker and place it in a vacuum chamber to remove air bubbles before use.

[0069] Prepare beakers and, in a fume hood, prepare 5% detergent, ethanol, deionized water, acetone, isopropanol, and plasma cleaner, respectively. Then, repeatedly immerse a quartz glass slide in each beaker sequentially for pre-cleaning. Store the cleaned quartz slide in an ethanol solution. Next, drop-cast the filtered PEDOT:PSS (200 μL) onto a silica matrix and allow it to dry overnight (at this point, the membrane and quartz glass slide are not yet separated).

[0070] The PEDOT:PSS membrane was immersed in CH3NO at room temperature for 10 min, rinsed with deionized water to remove residual CH3NO from the surface, and then heated on a hot plate at 80°C for 10 min to dry it (called dipping). Afterward, the CH3NO solution was dropped onto the sample and heated on a hot plate at 160°C for 15 min. It was then rinsed with deionized water to remove residual CH3NO and dried at 80°C for 10 min (called dropping).

[0071] The sample treated with CH3NO was immersed in concentrated H2SO4 at room temperature for 10 hours, then rinsed four times with deionized water to remove residual H2SO4, and then dried at 80℃ for 10 minutes.

[0072] The PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in different NaBH4 solutions for 30 min at room temperature, then rinsed four times in deionized water to remove residual NaBH4, and then dried at 80℃ for 30 min.

[0073] like Figure 10 As shown, different manufacturing processes can affect the power generation performance of thin films. Therefore, we fabricated three thin films with similar area and thickness using three different processes, and measured the voltage under different temperature differences to determine the optimal manufacturing process.

[0074] The experiment was conducted indoors using a variable control method, maintaining the room temperature at approximately 20°C. The voltage generated by the thin films under different temperature differences was determined by varying the temperature of the high-temperature heat source, with the temperature difference ranging from 30°C to 80°C. The experimental results are shown in the figure below. The generated voltage exhibits a roughly linear relationship with the temperature difference. By comparing the absolute values ​​and the slope, it can be seen that the thin film produced using Method 1 has significantly higher power generation performance, making it the optimal fabrication method.

[0075] For thin films, if the length is sufficient, the voltage generated at both ends is only positively correlated with the temperature difference between the heat source and the cold end. However, due to the limited space within the battery and the cost of thin film materials, thin films often cannot reach a sufficiently long length. Therefore, according to the law of thermal conductivity, we only need to cut a small section of the thin film with the highest thermal conductivity, and shorten the length of the film as much as possible while retaining ideal power generation performance, so as to maximize the "cost-effectiveness" of power generation, i.e., to find the critical length.

[0076] like Figure 11 As shown, the experiment was conducted indoors using a variable control method, maintaining the room temperature at approximately 20°C and the high-temperature heat source temperature at 37°C. A one-dimensional coordinate system was established with the leftmost end of the film as the origin. The distance between the temperature measurement point and the origin was denoted as x (mm), and the temperature difference between the film at x (mm) and the film at the origin was denoted as y (°C). As shown in the figure, a plateau was observed when x = 10 (mm), indicating that this was the contact point (33°C) between the film and the edge of the high-temperature heat source. The film length was calculated from this point. Since the temperature difference and the generated voltage are approximately linearly related under near-room temperature conditions, we can indirectly measure the voltage by measuring the temperature difference. By taking multiple measurements at x, we determined multiple relationships between y and x, thus obtaining an optimal length where the derivative of y with respect to x is small and the value of y is large—this is the critical length. The measured result was 25 mm. Incidentally, we also obtained an approximate functional graph of the temperature difference versus the film length, which is helpful for subsequent data determination.

[0077] Similar to the critical length, for thin films, if the width is sufficient, the voltage generated at both ends is only positively correlated with the temperature difference between the heat source and the cold end. However, also limited by the limited space within the battery and the cost of thin film materials, the width of the thin film should be made as narrow as possible while ensuring ideal power generation performance.

[0078] like Figure 9 As shown, the magnitude of the Seebeck effect depends on the flow rate of charge carriers between the hot and cold ends inside the thin film. However, the flow of charge carriers is affected by the edge effect. Therefore, finding the minimum critical width while minimizing the influence of the edge effect is an important part of improving the arrangement of thin film arrays.

[0079] like Figure 12As shown in the figure, under room temperature conditions, four different widths of films (1.25 mm, 2.5 mm, 5 mm, and 9 mm) were used to simulate the temperature difference between the human body and the external environment. The output voltage across the films was measured on the same substrate (substrate A). The changes in voltage over time t for films of different widths under a certain temperature difference were obtained, and the experimental data are shown in the figure. From the graph, it can be seen that a width of 2.5 mm results in a high voltage, requires less material, and exhibits relatively stable values; this is the critical width. Incidentally, we also obtained the voltage values ​​under substrate A simulating the temperature difference between the human body and room temperature, which is very helpful for the subsequent measurement of other data.

[0080] After completing the critical width experiment, in order to eliminate the interference of the substrate on the critical width measurement experiment and to investigate the influence of the substrate on the voltage generated by the thin film, another substrate B was used for a comparative experiment.

[0081] like Figure 13 As shown in the figure, under the same room temperature conditions, three films with different widths of 2.5 mm, 5 mm, and 9 mm were used to simulate the temperature difference between the human body and the external environment. The output voltage across the film was measured on the same substrate (substrate B). The changes in voltage generated by films of different widths under a certain temperature difference with time t were obtained, and the experimental data are shown in the figure. From the numerical values ​​in the image, it can be seen that the voltage generated is lower and more unstable when the width is 2.5 mm, and the voltage generated by all three film widths is lower than the experimental results on substrate A. Therefore, we conclude that different substrates have a significant impact on the voltage generated by the film, and substrate A is superior to substrate B, making it the most ideal substrate.

[0082] Since a single thin film generates a relatively small voltage, it is difficult to meet the needs of high-power electrical appliances. After determining the critical length, critical width, and optimal substrate, the series power generation performance of the thin film under these specifications was measured, and attempts were made to further increase the power generation voltage.

[0083] like Figure 14 As shown, multiple thin films with a critical area (25mm*2.5mm) using substrate A were first fabricated. These films were then connected in series using copper wires 2 with insulating sheaths. Silver paste 7 was then used to bond the contact points between the wires 2 and the films, securing the wires 2 and preventing contact loss. Voltage measurements were performed on systems with varying numbers of connected films under simulated human body temperature and environmental temperature differences. The figure shows that the generated voltage is essentially linear with the number of connected films, with minimal voltage loss. This result demonstrates that the series connection scheme is feasible and can effectively improve the output voltage.

[0084] After studying the power generation performance of the thin film, the optimal output voltage of the film at the human body and room temperature was determined, with values ​​in the millivolt range. Due to the small voltage order of magnitude, it is difficult to apply practically; further research is needed to boost the millivolt-level voltage to achieve practical application. We used a boost module for this experiment.

[0085] This boost module consists of three parts: a power boost module 5, an intermediate energy storage module, and a power regulator module. It can collect a 25mV electromotive force and output a stable 3.3V. When a 25mV input is received, a charge pump capacitor and a voltage transformer combine to output a slightly higher voltage to activate the LTC3108-1 chip. The voltage is amplified by the MOSFETs within the chip, achieving a 3.7V output without changing the power. This voltage is then fed into the supercapacitor in the intermediate energy storage section to store charge. This storage continues until the voltage across the capacitor reaches 3.7V, at which point it is output to the power regulator module. The power regulator module accepts input voltages from 1.8V to 5.5V and provides a stable 3.3V output. When the capacitor in the intermediate energy storage section outputs voltage, it activates the TPS63900 chip, which, through the combination of its internal MOSFETs, achieves a stable 3.3V output.

[0086] Experimental data such as Figure 15 As shown, under voltage input conditions of 25mA and 3mA, the voltage of capacitor 6 gradually increases from 53.25mV. Calculations show that under the above conditions, it takes 30 minutes to charge a 1.5F capacitor 6 to 4.5V using this module. This demonstrates that this thin film can output high voltages, reaching the voltage level of a typical battery, thus proving its practicality.

[0087] A PEDOT:PSS flexible thermoelectric thin film material innovatively employs a drop casting technique to form a flexible film on a quartz glass substrate. This is followed by a secondary treatment with formamide, sulfuric acid, and sodium borohydride. Optimal processing conditions were achieved by adjusting the concentration of the solution and varying the treatment time. After film formation, annealing at 140°C for 10 minutes was performed. The resulting flexible thermoelectric thin film material exhibited a power factor of 141 μWm⁻¹K⁻² at 25°C. Immersing the fabricated film in acetone dissolves it, yielding independent flexible thermoelectric thin films. These can be assembled into power supply arrays using conductive copper wires arranged on a polyimide substrate. Testing showed that the output power density of the film reached 1 μWcm⁻² when using a human arm as a heat source, demonstrating significant potential for powering smart wearable devices. The flexible thermoelectric thin film material has low manufacturing costs, the fabrication process is suitable for mass production, and it has broad application prospects.

[0088] The thin film produced using this process is impact-resistant and freely bendable, exhibiting excellent flexibility and bending properties, as well as good mechanical properties. It leads in flexibility among all currently practical thermoelectric materials. Utilizing the film's flexibility, the battery can be fabricated into a flexible structure, enhancing its bending performance and solving the problem of battery damage caused by bending and impact, thus expanding the battery's application environment and usage methods. Due to the excellent flexibility and extremely thin thickness of the film used in this product, the output voltage can be significantly increased within the limited space of the battery through dense series connection, thereby raising the product's performance ceiling.

[0089] Based on the thermoelectric power generation principle of PEDOT:PSS flexible thermoelectric film, we innovated the connection method between the film and the circuit. Utilizing the principle that a temperature difference between the two ends of the thermoelectric film generates voltage, we cut the thermoelectric film to a size of 2*25 (mm) and connected multiple films on a self-made flexible circuit board. At the connection points between the film and the internal conductors 2 of the flexible circuit board, silver paste was used for a sealed connection, thereby reducing voltage and current loss. The oblique series connection between the films significantly improves the area power generation efficiency of the circuit board. To create hot and cold ends, we intercalated the film within a ceramic fiber layer 4, insulated both ends of the film, and covered the film with insulating graphite 8, thus forming two temperature cavities to achieve the thermoelectric power generation effect.

[0090] A self-generating battery based on PEDOT:PSS flexible thermoelectric thin film simulates the temperature difference between the human body and room temperature. It was found that a thin film of a critical length (0.2*2.5=0.5cm²) can generate approximately 0.4mV at a temperature difference of 30 degrees Celsius. This is 1-2 orders of magnitude higher than current purely organic thermoelectric devices, and even higher than some rigid semiconductor materials. An initial voltage of approximately 20mV-25mV is achieved through multi-layer film series connection. When 25mV is input, a slightly larger voltage is first output by a charge pump capacitor and voltage transformer combination to start the LTC3108-1 chip. The voltage is amplified by the MOSFET in the chip, achieving an output of 3.7V without changing the power. This voltage is then fed into a supercapacitor in the intermediate energy storage section to store charge, continuing to store charge until the voltage across the capacitor rises to 3.7V, at which point it is output to the power supply regulator module. The power supply regulator module accepts input voltages from 1.8V to 5.5V and provides a stable output of 3.3V. When the capacitor in the intermediate energy storage section outputs voltage, the TPS63900 chip is activated. The combination of internal MOSFETs within the chip then achieves a stable 3.3V output. Connecting the voltage to a 1.5F capacitor and testing showed that the capacitor was fully charged in approximately 20 minutes.

[0091] Currently, the most mature and widely used self-generating technologies are solar photovoltaic power generation and semiconductor thermoelectric power generation, as shown in the table below for a comparison of self-generating technologies:

[0092]

[0093] By comparing the different self-generating technologies in the table above, it can be concluded that thermoelectric thin-film power generation technology has unique advantages and application characteristics. With the development of science and technology, thermoelectric thin-film material thermoelectric power generation technology may also become a common environmentally friendly power generation technology.

[0094] The current PEDOT:PSS preparation technology is in its initial development stage. The mainstream preparation methods mainly involve flexible films and polyester fiber fabrics. Table 2 below compares the PEDOT:PSS preparation processes.

[0095]

[0096] In this product, we use a relatively simple flexible thin film preparation method and design a high-efficiency thin film arrangement to improve thin film power generation efficiency and enhance product performance.

[0097] Currently, mainstream thermoelectric power generation technology mainly utilizes the temperature difference between different water layers to generate electricity. The principle is that warm water flows into the evaporation chamber, boils under low pressure, and becomes flowing steam, which drives a turbine to rotate, starting an AC motor to generate electricity. The used steam enters the condensation chamber, is cooled and condensed by deep water, and is then recycled. As shown in Table 2, using PEDOT:PSS flexible thermoelectric film to generate electricity using the temperature difference between body temperature and air solves the problems of excessively large power generation devices and complex technical requirements that limit thermoelectric power generation.

[0098] Most existing smart wearable devices require repeated charging, have heavy and inflexible batteries, and their cumbersome functions and complicated operations can easily lead to a poor user experience. They also often become unusable in emergencies because users forget to charge them, causing inconvenience to consumers.

[0099] Based on the optimized PEDOT:PSS flexible film of this invention, conductive copper wires can be arranged and assembled on a polyimide substrate to form a power supply array. Utilizing the Seebeck effect, a voltage is generated by leveraging the temperature difference between the human skin surface and the surrounding environment. This can completely replace the power supply solutions of other low-power devices, or assist in the power supply of high-power devices, extending battery life. Furthermore, its flexibility and thinness make it ideal for application in the field of smart wearable devices. Experimental tests show that at a temperature difference of 30 degrees Celsius, the voltage generated by the flexible thin-film thermoelectric battery is 1-2 orders of magnitude higher than that of the best current pure organic thermoelectric devices, which has practical significance for the innovation of power supplies for wearable devices.

[0100] Due to limitations in thermoelectric conversion efficiency and manufacturing costs, thermoelectric power generation technology has long been primarily used in cutting-edge fields such as aerospace and military, with limited civilian applications. However, in recent years, thermoelectric power generation technology has received increasing attention from governments and researchers, making its civilian application possible and indicating a promising market prospect.

[0101] Therefore, based on the characteristics of this product—its softness, lightness, and ability to generate electricity through thermal differences without requiring charging—we position ourselves in two market segments: low-power, simple smart wearable devices and auxiliary charging for high-power smart wearable devices.

[0102] (a) Low-power simple smart wearable devices refer to wearable devices that only include simple functions, and the target consumers include special groups such as the elderly and people with disabilities.

[0103] (b) The auxiliary charging function of high-power smart wearable devices refers to the use of thermoelectric power generation to charge the main battery to extend the battery life when the wearable device is not in operation.

[0104] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two elements; they can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0105] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing a PEDOT:PSS flexible thermoelectric thin film, characterized in that, include: Filtering PEDOT:PSS removes large particles from the aqueous solution, and placing the filtrate in a vacuum chamber removes air bubbles before use; Multiple cleaning agents were prepared, and quartz glass slides were repeatedly immersed in the multiple cleaning agents for pre-cleaning. The cleaned quartz glass slides were then stored in an ethanol solution. The filtered PEDOT:PSS was drop-cast onto a quartz glass matrix and dried overnight at 60°C. The PEDOT:PSS membrane on the quartz glass substrate was completely immersed in CH3NO at room temperature for 30 minutes, and the residual CH3NO was removed from the surface of the PEDOT:PSS membrane by rinsing with deionized water. Heating to dry the cleaned PEDOT:PSS membrane, dropping CH3NO solution onto the PEDOT:PSS membrane, heating on a hot plate, rinsing with deionized water to remove residual CH3NO, and drying the PEDOT:PSS membrane at 60°C for 10 min. The PEDOT:PSS membrane treated with CH3NO was immersed in concentrated H2SO4 at room temperature, then rinsed repeatedly with deionized water to remove residual H2SO4, and then dried. PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in NaBH4 solutions of different concentrations at room temperature for treatment, then rinsed in deionized water to remove residual NaBH4, and then dried at 60℃ for 10 min to obtain PEDOT:PSS flexible thermoelectric thin films.

2. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 1, characterized in that, The PEDOT:PSS flexible thermoelectric film is cut into several pieces, and each piece of the PEDOT:PSS flexible thermoelectric film is placed on a film carrier. Each piece of the PEDOT:PSS flexible thermoelectric film is arranged in an oblique manner, and each piece of the PEDOT:PSS flexible thermoelectric film is connected in series by a wire.

3. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 2, characterized in that, The upper and lower surfaces of the PEDOT:PSS flexible thermoelectric film are coated with insulating graphite to insulate both ends of the PEDOT:PSS flexible thermoelectric film, thus forming a hot and cold end.

4. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 3, characterized in that, The PEDOT:PSS flexible thermoelectric film is inserted into the ceramic fiber layer in the middle, so that the two ends of the PEDOT:PSS flexible thermoelectric film are respectively in two temperature cavities formed by the ceramic fiber layer and the upper and lower graphite layers.

5. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 2, characterized in that, The conductor is a copper conductor with an insulating outer sheath, and the contact area between the conductor and the PEDOT:PSS flexible thermoelectric film is sealed with silver paste.

6. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 1, characterized in that, Prepare multiple containers and rinse them with deionized water. Place them in an oven to dry for 10 minutes. Use a vacuum-assisted syringe to filter PEDOT:PSS to remove large particles from the aqueous solution. After filtration, put the filtrate in another beaker and place the filtrate in a vacuum chamber to remove air bubbles before use. Prepare 5% detergent, ethanol, deionized water, acetone, isopropanol and plasma cleaner in a fume hood. Then, quartz glass slides are repeatedly immersed in the various cleaners in sequence for pre-cleaning. After cleaning, the quartz glass slides are stored in an ethanol solution.

7. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 1, characterized in that, The PEDOT:PSS membrane was immersed in CH3NO at room temperature for 10 min, rinsed with deionized water to remove residual CH3NO from the surface, and then heated on a hot plate at 80°C for 10 min to dry it. Then, the CH3NO solution was dropped onto the PEDOT:PSS membrane, heated on a hot plate at 160°C for 15 min, rinsed with deionized water to remove residual CH3NO, and dried at 80°C for 10 min. The sample treated with CH3NO was immersed in concentrated H2SO4 at room temperature for 10 hours, then rinsed four times with deionized water to remove residual H2SO4, and then dried at 80°C for 10 minutes. The PEDOT:PSS membranes treated with CH3NO and H2SO4 were immersed in different NaBH4 solutions at room temperature for 30 min each, then rinsed four times in deionized water to remove residual NaBH4, and finally dried at 80°C for 30 min.

8. The process for preparing a PEDOT:PSS flexible thermoelectric thin film according to claim 4, characterized in that, A power collection module and a capacitor are electrically connected to each of the series-connected PEDOT:PSS flexible thermoelectric films.

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