A thermoelectric thin film and a method of manufacturing the same

Abstract

The application relates to a thermoelectric film and a preparation method thereof, and belongs to the technical field of thermoelectric conversion. The application provides a preparation method for preparing a polycyclonaphthalene thermoelectric film by a laser direct writing method with 3,4,9,10-perylenetetracarboxylic acid (PTCA) as a precursor: a metal ion layer is modified on the surface of a support substrate; an organic solution of PTCA is coated on the preheated modified substrate, and a perylenetetracarboxylic dianhydride film is formed after drying and thermal condensation; and the film on the substrate is in-situ converted into a polycyclonaphthalene thermoelectric film by a laser direct writing technology. The application belongs to normal-temperature normal-pressure preparation technology, and the process is convenient and easy to realize large-area and patterned preparation; and the application does not need complex chemical derivation and metal chelation steps, avoids the introduction of exogenous metal impurities from the source, and can obtain a polycyclonaphthalene film with good conductivity, which is used for thermoelectric application. The obtained thermoelectric film can be conveniently transferred to a flexible substrate, and has application prospects in the fields of flexible thermoelectric sensing and low-grade waste heat recovery.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric materials technology, and in particular to a thermoelectric thin film and its preparation method. Background Technology

[0002] Thermoelectric thin films can directly convert low-grade temperature differences into electrical energy output, showing significant application prospects in wearable sensing, flexible electronics, and biomedicine. Compared to inorganic thermoelectric materials, thermoelectric thin films based on conductive polymers have advantages such as flexibility, lightweight, solution-processability, low toxicity, and lower cost, demonstrating significant potential in low-grade waste heat recovery, distributed power supply for the Internet of Things, and flexible solid-state refrigeration.

[0003] Among common polymeric thermoelectric materials, polycyclic naphthalene exhibits excellent electrical conductivity, thermal stability, and chemical stability due to its conjugated long-chain structure and abundant delocalized electrons, thus possessing significant application value in the field of thermoelectric thin films. Current methods for preparing polycyclic naphthalene thin films primarily utilize insoluble and infusible perylene tetracarboxylic dianhydride (PTCDA) as a precursor, inducing perylene radicals through thermal, laser, or plasma methods, followed by vapor-phase polymerization and deposition onto the substrate surface. These methods involve processes such as thermochemical vapor deposition, pulsed laser ablation deposition, or plasma-enhanced chemical vapor deposition, typically requiring high temperature and high vacuum conditions, resulting in stringent processes, high costs, difficulty in achieving patterning, and inconvenience in large-area fabrication.

[0004] Furthermore, existing technologies convert insoluble and infusible PTCDA into a water-soluble salt and then chelate it with metal ions to improve the thermal and photothermal stability of the PTCDA salt, thereby preparing a metal chelate precursor film of PTCDA salt. Subsequently, this precursor film is subjected to laser direct writing to obtain a polycyclic naphthalene film. However, this preparation process introduces a large amount of metal elements into the precursor. In the final polycyclic naphthalene film, the metal residue exists in the conductive polymer network in the form of oxides, forming scattering centers, which is detrimental to carrier transport and thus affects the electrical properties of the film. Its conductivity is lower than that of polycyclic naphthalene films prepared by methods such as thermochemical vapor deposition, pulsed laser ablation deposition, or plasma-enhanced chemical vapor deposition (traditional methods: ~10). -2 – 10 S / cm; Laser direct writing preparation technology using PTCDA salt as a precursor: ~ 1 × 10 -3 (S / cm). Since the thermoelectric properties of polycyclic naphthalene films largely depend on their electrical conductivity (higher conductivity corresponds to a higher Seebeck coefficient), although this technique is relatively convenient, the resulting polycyclic naphthalene films cannot be used in thermoelectric films. The key to developing low-cost thermoelectric films lies in how to prepare polycyclic naphthalene films with good electrical conductivity using inexpensive, room-temperature, and ambient-pressure continuous laser direct-writing processing technology. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a thermoelectric thin film and its preparation method, particularly a polycyclic naphthalene thermoelectric thin film and its preparation method, aiming to achieve a convenient preparation technology for polycyclic naphthalene thin films with good electrical conductivity, so as to apply them to thermoelectric thin films.

[0006] To achieve the above objectives, the preparation method of the thermoelectric thin film of the present invention uses 3,4,9,10-perylenetetracarboxylic acid (PTCA) from the perylene aromatic compounds as the building block of polycyclic naphthalene. PTCA has the same conjugated perylene core as PTCDA or PTCDA salts, and its four free carboxyl groups endow the molecule with strong polarity and hydrogen bonding ability, making it soluble in organic solvents. The preparation process includes the following steps: 1) modifying the substrate surface with a metal ion layer to induce the orderly and uniform adsorption of PTCA molecules on the substrate surface; 2) coating the PTCA solution onto the heated substrate surface modified with the metal ions, and then drying and thermally condensing to form a PTCDA thin film; 3) converting the PTCDA thin film in situ into a polycyclic naphthalene conductive polymer film by laser irradiation pyrolysis. This film can be used directly as a thermoelectric thin film, or it can be transferred to a flexible substrate for use as a flexible thermoelectric thin film.

[0007] This invention is achieved through the following technical solution:

[0008] The first objective of this invention is to provide a method for preparing a thermoelectric thin film, comprising the following steps:

[0009] S1. Pre-modify the surface of the support substrate with metal ions;

[0010] S2. An organic solution of 3,4,9,10-perylenetetracarboxylic acid (PTCA) is coated onto the surface of the modified metal ion support substrate obtained in step S1 after preheating, and then dried and thermally condensed to form a perylenetetracarboxylic acid dianhydride (PTCDA) film.

[0011] S3. The perylenetetracarboxylic acid dianhydride film on the support substrate is subjected to laser direct writing to form a thermoelectric film on the support substrate.

[0012] The present invention pre-modifies the surface of the support substrate with iron ions to improve wettability and spreadability. The metal ions are only present on the surface of the thermoelectric film and do not affect the conductivity and thermoelectric properties of the film itself.

[0013] In one embodiment of the present invention, in step S1, the room temperature thermal conductivity of the supporting substrate is 1 W / (m·K)-10 W / (m·K), and the coefficient of thermal expansion is 1×10⁻⁶. -7 / ℃-20×10 -7 / ℃, heat resistance temperature greater than 800℃, surface roughness less than 2 nm.

[0014] In one embodiment of the present invention, in step S1, the material of the supporting substrate is selected from quartz, mica, silicon wafer, glass, aluminum sheet, stainless steel sheet or ceramic sheet; preferably quartz.

[0015] In one embodiment of the present invention, in step S1, the modified metal ion is one or more of iron ions, aluminum ions and chromium ions, which is formed on the support substrate by coating a solution of metal salt (such as chloride, sulfuric acid compound, etc.) and drying to remove the solvent.

[0016] In one embodiment of the present invention, in step S1, the method of metal ion modification includes: directly forming a coating containing metal salt on the clean support substrate surface by coating method.

[0017] In one embodiment of the present invention, in step S1, the coating method is selected from one or more of spin coating, spray coating, drop coating and dip coating.

[0018] In one embodiment of the present invention, in step S1, the amount of metal ions modified on the surface of the support substrate is 1×10⁻⁶. -5 mmol / cm 2 -2×10 -5 mmol / cm 2 .

[0019] In one embodiment of the present invention, in step S2, the 3,4,9,10-perylenetetracarboxylic acid is dissolved in an organic solvent and heated and stirred until completely dissolved to prepare a PTCA precursor solution with a concentration of 0.05 mmol / L-0.5 mmol / L.

[0020] And / or, the organic solvent of the organic solution containing 3,4,9,10-perylenetetracarboxylic acid is one or more of dimethyl sulfoxide, N,N-dimethylformamide, chlorobenzene and N-methylpyrrolidone.

[0021] In one embodiment of the present invention, in step S2, the coating method is preferably spraying. The preheating temperature of the supporting substrate is 180℃-270℃; the drying time for the drying heat condensation is 1 min-10 min.

[0022] In one embodiment of the present invention, in step S2, the PTCA precursor solution is sprayed onto a preheated substrate, and the substrate temperature is used to promote the rapid evaporation of the solvent, thereby depositing and undergoing a thermal condensation reaction to form a uniform PTCDA film.

[0023] In one embodiment of the present invention, in step S2, the thickness of the perylene tetracarboxylic acid dianhydride film is controlled to be 200 nm-800 nm, preferably 250 nm-700 nm, by controlling the volume of the sprayed solution.

[0024] In one embodiment of the present invention, in step S3, the process conditions for the laser direct writing process are: laser wavelength of 1064 nm-10.64 μm, laser linear energy density of 20 J / m-40 J / m, preferably 30 J / m-33 J / m.

[0025] In one embodiment of the present invention, after step S3, the conductive polymer film obtained on the support substrate can be directly used as a thermoelectric film.

[0026] And / or, the conductive polymer film can be transferred from the original support substrate surface to other flexible or rigid substrates through transfer technology to form a composite thermoelectric device.

[0027] A second objective of this invention is to provide a thermoelectric thin film prepared by the above-described method, having a thickness of 100 nm to 500 nm.

[0028] In one embodiment of the present invention, the thermoelectric thin film has a conductivity of 1 s / cm-200 s / cm, a Seebeck coefficient of 1 μV / K-10 μV / K, and a power factor of 0.5 μW / (cm·K). 2 )-10 μW / (cm·K 2 ).

[0029] In one embodiment of the present invention, the thermoelectric thin film can be processed into geometric shapes and sizes of arbitrary shapes or sizes, or combinations of multiple shapes, suitable for flexible device integration.

[0030] A third objective of this invention is to provide a thermoelectric component comprising the aforementioned thermoelectric thin film; the thermoelectric thin film is disposed on a supporting substrate or integrated onto the surface of a target substrate by transfer printing. It may comprise the aforementioned thermoelectric thin film supported by a rigid substrate, or it may be a flexible thermoelectric thin film formed by transferring the thermoelectric thin film from a rigid substrate using a flexible polymer.

[0031] PTCDA is a commonly used precursor in conventional polycyclic naphthalene film preparation methods such as thermochemical vapor deposition, pulsed laser ablation deposition, or plasma-enhanced chemical vapor deposition. However, its poor solubility makes it unsuitable for solution-based film formation. In contrast to PTCDA, this invention uses PTCA, which is soluble in organic solvents, as a precursor. A precursor film is formed through a thermal coating process, and during film formation, PTCA undergoes a condensation reaction, followed by dehydration to form a PTCDA intermediate film.

[0032] Furthermore, laser direct writing technology was used as a processing method to perform laser pyrolysis of PTCDA films under ambient temperature and pressure conditions, achieving a convenient conversion from PTCA precursor to polycyclic naphthalene thermoelectric films. Compared with conventional methods for preparing polycyclic naphthalene thermoelectric films, this technical route avoids the use of expensive equipment and harsh conditions such as high temperature and high pressure, significantly simplifying the process. Simultaneously, it eliminates the need for complex chemical derivatization or metal ion chelation modification, avoiding the introduction of non-carbon elements, thus obtaining polycyclic naphthalene films with excellent electrical conductivity, which can be directly used as thermoelectric films. This preparation method is simple, has mild reaction conditions, is environmentally friendly, and is easy to implement for large-area, low-cost manufacturing, providing a reliable and efficient pathway for the engineering application of polymer thermoelectric materials.

[0033] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0034] (1) This invention uses soluble PTCA as a precursor, combining in-situ condensation of the solution through thermal coating and laser direct writing technology to prepare thermoelectric thin films at room temperature and pressure. During the thermal coating process, the PTCA solution undergoes in-situ condensation to obtain a PTCDA thin film with good thermal stability, eliminating the need for metal chelation steps and providing a precursor suitable for laser pyrolysis. Based on this, the film is pyrolyzed in-situ using laser direct writing technology, transforming it into a polycyclic naphthalene conductive polymer film. This process avoids the introduction of metal ions, resulting in a final film free of metal impurities and exhibiting good conductivity, making it suitable as a thermoelectric thin film.

[0035] (2) The present invention adopts solution thermal film formation combined with iron ion pre-modification on the substrate surface, which effectively improves the wettability and spreadability of PTCA solution on the hot substrate. Thus, a uniform precursor film that can be used for laser pyrolysis can be efficiently prepared through a simple hot substrate assisted spray deposition technology. Combined with laser direct writing technology, the whole process is mild and easy to operate.

[0036] (3) The preparation method described in this invention has good controllability and flexibility. By precisely controlling the thickness of the precursor film and the laser processing parameters (such as power, scanning speed, etc.), the microstructure and chemical state of the final thermoelectric film can be flexibly adjusted, thereby optimizing the thermoelectric properties such as film conductivity, Seebeck coefficient, and power factor.

[0037] (4) The thermoelectric thin film prepared by the present invention has the advantages of convenient processing, green environmental protection, low cost and good flexibility, and shows good application prospects in thermoelectric sensing and energy conversion fields such as wearable electronics, distributed Internet of Things power supply and low-grade waste heat recovery. Attached Figure Description

[0038] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0039] Figure 1 SEM image of PTCA raw material (a), infrared spectrum of PTCA, and image of powder (b);

[0040] Figure 2 Photograph of PTCA in dimethyl sulfoxide (DMSO) solution;

[0041] Figure 3 This is a schematic diagram of the reaction process by which PTCA is converted into PPN through the preparation process described in this patent.

[0042] Figure 4 (a) Photograph and (b) infrared spectrum of precursor thin film prepared for heated substrate spraying technology;

[0043] Figure 5 The spraying effect diagrams are for Comparative Example 1(a) and Example 1(b);

[0044] Figure 6 Scanning electron microscope (SEM) images of precursor films prepared by heated substrate spray deposition technology; wherein, (a), (b), and (c) correspond to precursor films with sprayed PTCA / DMSO solution volumes of 10 mL, 30 mL, and 50 mL, respectively.

[0045] Figure 7 AFM spectra of PTCA films obtained by spraying with different volumes of PTCA solution are shown; where (a), (b), and (c) correspond to precursor films with sprayed PTCA / DMSO solution volumes of 10 mL, 30 mL, and 50 mL, respectively.

[0046] Figure 8 The ultraviolet spectra of PTCA films obtained by spraying with different volumes of PTCA solution are shown.

[0047] Figure 9 Images of samples obtained under different laser processing powers for a PTCA precursor film with a thickness of 648.1 nm.

[0048] Figure 10 Scanning electron microscope (SEM) images of a PTCA precursor film with a thickness of 648.1 nm, obtained under different laser processing powers.

[0049] Figure 11The images show the UV spectra of PTCA precursor films of different thicknesses obtained under different laser processing powers; where (a) is a PTCA precursor film with a thickness of 252.4 nm, (b) is a PTCA precursor film with a thickness of 648.1 nm, and (c) is a PTCA precursor film with a thickness of 853.3 nm.

[0050] Figure 12 Raman spectra of PTCA precursor films of different thicknesses obtained under different laser processing powers; where (a) is a PTCA precursor film with a thickness of 252.4 nm, (b) is a PTCA precursor film with a thickness of 648.1 nm, and (c) is a PTCA precursor film with a thickness of 853.3 nm.

[0051] Figure 13 The Raman spectral peak fitting and corresponding optical morphology of the two characteristic products are shown; (a) exhibits typical polycyclic naphthalene structural characteristics (significant ~1300 cm⁻¹). -1 (a) Representative Raman spectra of the CH peak and their peak fitting results; (b) Typical graphitized carbon structure characteristics (~1300 cm⁻¹) -1 The representative Raman spectra of the peaks disappearing, with significant G and D bands, and their peak fitting results;

[0052] Figure 14 The temperature-time curve (a) and thermoelectric voltage response graph (b) of the sample in the thermoelectric measurement are shown.

[0053] Figure 15 According to Figure 13 The experimental results and the linear analysis of the correlation between the obtained thermoelectric voltage and temperature difference;

[0054] Figure 16 Photograph of the thermoelectric thin film transferred onto a polyimide film;

[0055] Figure 17 Ring-shaped wearable temperature sensor and its application demonstration. Detailed Implementation

[0056] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0057] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0058] Example 1

[0059] This embodiment provides a method for preparing a thermoelectric thin film, the specific steps of which are as follows:

[0060] S1. Pre-modification of the support substrate surface with iron ions:

[0061] After ultrasonically cleaning the quartz substrate with deionized water and isopropanol, it was dried in an oven at 100°C for 20 minutes. Immediately after removal, it was preheated on a hot plate at 200°C for 2 minutes. A 1 mmol / L FeCl3 ethanol solution was then uniformly sprayed onto the preheated quartz substrate surface to obtain a FeCl3 modified layer with an iron ion coating amount of 1.5 × 10⁻⁶. -5 mmol / cm 2 .

[0062] S2. Prepare PTCA precursor films on the modified substrate surface:

[0063] SEM images of PTCA raw material and infrared spectrum of PTCA powder, along with photographs of the powder, are shown below. (PTCA 3,4,9,10-perylenetetracarboxylic acid (PTCA, 98% purity). Figure 1 The precursor (shown in the image) was dissolved in dimethyl sulfoxide (DMSO) and reacted continuously at a constant temperature of 120°C with magnetic stirring for 2 hours to prepare a homogeneous PTCA / DMSO solution with a concentration of 0.30 mmol / L. Figure 2 As shown, the solution appears as a uniform, clear red liquid, indicating good solubility. This solution was sprayed onto a preheated substrate treated with S1 at 200°C. After spraying, the substrate was held at 200°C for 1 minute to induce condensation, resulting in a uniformly thick perylenetetracarboxylic acid dianhydride film (precursor film). The reaction is as follows... Figure 3 As shown. The shape of the film obtained when the volume of the sprayed liquid is controlled to be 30 mL is as follows. Figure 4 As shown in (a), this process exhibits good film-forming properties; furthermore, Figure 1 (b) in the sample exhibits a dark red color similar to that of the PTCA raw material powder, as compared with the membrane ( Figure 4 ) and PTCA raw powder ( Figure 1 The FITR spectra of both samples show that there is a peak at approximately 1595 cm⁻¹. -1 C = C tensile vibration at approximately 1757 cm -1 The characteristic absorption band of the perylene nucleus, resulting from the C=O stretching vibration, is observed at ~3459 cm⁻¹. However, this absorption band is not observed in the PTCA powder at ~3459 cm⁻¹. -1 and ~1384 cm -1The stretching and in-plane bending vibrations of the OH groups (related to the free carboxylic acid in PTCA). The difference between the infrared spectrum of the sprayed film and that of the PTCA powder indicates that PTCA undergoes a dehydration condensation reaction and is converted into PTCDA during the heat-assisted spraying process.

[0064] S3. Laser direct writing process for the precursor thin film:

[0065] A CO2 laser with a wavelength of 10.64 μm was used to perform direct laser writing on the above-mentioned PTCA precursor film under normal temperature and pressure air environment. The laser writing speed was 30 mm / s, and finally a polycyclic naphthalene conductive polymer film, i.e. a thermoelectric film, was obtained.

[0066] Example 2

[0067] This embodiment provides a method for preparing a thermoelectric thin film, which is similar to that of Embodiment 1, except that in step S2, the volume of the PTCA / DMSO solution sprayed is 10 mL; the remaining steps are consistent with those of Embodiment 1.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing a thin film, similar to Example 1, except that the surface of the supporting substrate is not modified with iron ions. The specific steps are as follows:

[0070] Using the same PTCA as in Example 1 as the precursor, a PTCA / DMSO solution of the same concentration was prepared. The solution was directly sprayed onto a quartz substrate that had only been cleaned, dried, and preheated at 200°C for 2 minutes to form a PTCA precursor film.

[0071] from Figure 5 As can be seen, a uniform precursor film cannot be obtained by spraying PTCA onto a substrate that has not been modified with iron ions.

[0072] Comparative Example 2

[0073] This comparative example provides a method for preparing a thin film, similar to Example 1, except that in step S2, the volume of the sprayed liquid is 50 mL. Figure 12 As can be seen from (c) in the figure, under different laser writing energy densities, the result is only 1350 cm⁻¹. -1 and 1580 cm -1 The peaks are typical of carbon materials. This indicates that under different laser writing energy densities, excessively thick PTCA precursor films cannot yield polycyclic naphthalene polymers, but only carbon materials.

[0074] Performance testing

[0075] Figure 6Scanning electron microscope (SEM) images of precursor films prepared by hot substrate-assisted spray deposition technology in Examples 1-2 and Comparative Example 2 are shown. It can be seen that precursor films with different spray amounts have different surface morphologies, reflecting different stacking conditions of the precursor films.

[0076] Figure 7 The AFM spectra of the films obtained in Examples 1-2 and Comparative Example 2 show that the film thicknesses corresponding to the sprayed PTCA / DMSO solution volumes of 10 mL, 30 mL, and 50 mL are 252.4 nm, 648.1 nm, and 853.3 nm, respectively.

[0077] Figure 8 The images show the UV spectra of films obtained by spraying with different volumes of PTCA solution. It can be seen that the absorbance increases with increasing thickness. Furthermore, the typical light absorption peaks of PTCA are also observed.

[0078] Figure 9 The images show samples of a precursor film with a thickness of 648.1 nm (Example 1) obtained under different laser processing powers (0.81 W, 0.87 W, 0.93 W, 0.99 W, 1.05 W, and 1.11 W). It can be seen that under these laser writing conditions, a black, glossy film was obtained at the laser irradiation site, showing a significant difference from the original red precursor film.

[0079] Figure 10 Scanning electron microscope (SEM) images of a PTCA precursor film with a thickness of 648.1 nm (Example 1) obtained under different laser processing powers (0.84 W, 0.87 W, 0.90 W, 0.93 W, 0.96 W, and 0.99 W). It can be seen that under different laser irradiation conditions, the heating of the precursor film after photothermal conversion varies, resulting in different surface morphologies of the film.

[0080] Figure 11 The UV-Vis spectra of films with thicknesses of 252.4 nm (Example 2), 648.1 nm (Example 1), and 853.3 nm (Comparative Example 2) after laser direct writing were compared under different laser powers. Under the same laser processing conditions, film thickness plays a crucial role in the photothermal conversion of laser beam energy. The greater the film thickness, the higher its absorbance and photothermal conversion efficiency, and the higher the temperature rise in the laser-irradiated region of the precursor film. In this invention, the thickness of the precursor film is key to influencing the structure and properties of the corresponding polycyclic naphthalene film. The results of the influence of laser power and precursor film thickness on the structural evolution of the polycyclic naphthalene thermoelectric film proposed in this invention show that, compared with the film without laser processing (… Figure 8 Compared to, in Figure 11 As clearly seen in (a), for a precursor film with a thickness of 252.4 nm, samples treated with 0.84 W, 0.87 W, and 0.90 W lasers all exhibited perylene core absorption characteristics in the 400-600 nm range. This indicates that the precursor conversion was incomplete under these conditions. This suggests that when the precursor film is too thin or the laser power is insufficient, the temperature rise caused by laser heating is insufficient to induce the decarboxylation and polymerization reactions of PTCDA molecules, thus failing to convert the precursor into polycyclic naphthalene. However, this characteristic peak weakened under laser power treatments of 0.93 W, 0.96 W, and 0.99 W. Figure 11 (b) shows the UV spectra of a precursor film with a thickness of 648.1 nm (Example 1) obtained at different laser processing powers. It can be seen that at low powers (0.84 W, 0.87 W), the precursor film still exhibits characteristic peaks, indicating that under these conditions, the energy is insufficient to convert PTCDA into polycyclic naphthalene. In contrast, a precursor film with a thickness of 853.3 nm processed within the same laser power range... Figure 11 (c) in the middle does not have this absorption property at all.

[0081] Figure 12 The Raman spectra of thin films with thicknesses of 252.4 nm (Example 2), 648.1 nm (Example 1), and 853.3 nm (Comparative Example 2) after laser direct writing are shown below, obtained under different laser powers. It can be seen that the precursor film with a thickness of 252.4 nm retains the characteristic peaks of polycyclic naphthalene at different laser powers. Figure 11 (a) and Figure 1 Results (a) show that polycyclic naphthalene films can be successfully obtained in films with a thickness of 235 nm under laser writing conditions of 0.90 W, 0.93 W, and 0.99 W. The precursor film with a thickness of 647 nm only exhibits a 1350 cm⁻¹ pattern under high-power (0.96 W, 0.99 W) laser conditions. -1 and 1580 cm -1 The laser exhibits typical characteristic peaks for carbon materials. This indicates that polycyclic naphthalene cannot be obtained under these laser conditions; instead, carbon materials are produced. (Combined with...) Figure 11 (b) and Figure 12 Results (b) show that for a 648.1 nm thick film, laser writing conditions of 0.90 W and 0.93 W are required to successfully obtain a polycyclic naphthalene film. For the 853.3 nm thick precursor film, only 1350 cm⁻¹ is achieved under different laser writing energy densities. -1 and 1580 cm -1The peaks are typical of carbon materials. This indicates that with excessively thick precursor films, polycyclic naphthalene polymers cannot be obtained under different laser writing energy densities; only carbon materials can be produced.

[0082] Figure 13 For a precursor film with a thickness of 648.1 nm, Raman spectral peak fitting and corresponding optical morphology of two characteristic products were obtained under laser processing powers of 0.9 W and 0.99 W. (a) Representative Raman spectra exhibiting typical polycyclic naphthalene structural characteristics (significant CH peak at ~1300 cm⁻¹) and their peak fitting results. (b) Representative Raman spectra exhibiting typical graphitized carbon structural characteristics (disappearance of the ~1300 cm⁻¹ peak, significant G and D bands) and their peak fitting results. The inset shows optical microscope images of the corresponding spectral acquisition areas. It can be seen that under high-power laser conditions, polycyclic naphthalene cannot be obtained; instead, carbon materials are obtained.

[0083] Based on the resistance results and sample geometry, the dependence of the conductivity (σ) of precursor films with thicknesses of 252.4 nm and 648.1 nm obtained by laser direct writing on laser power was calculated. For the 252.4 nm thick sample, the conductivity increased from 10 S / cm at 0.93 W to 74 S / cm at 0.96 W; for the 648.1 nm thick film, it increased from 2 S / cm at 0.9 W to 10 S / cm at 0.93 W. The conductivity increased with increasing laser power. This conductivity value is superior to that obtained by traditional methods for polycyclic naphthalene films.

[0084] Figure 14 The temperature gradient and corresponding thermoelectric voltage response applied across the sample (precursor film thickness ~648.1 nm, laser power 0.93 W) during thermoelectric measurement are shown. A negative value indicates that the sample is a p-type semiconductor.

[0085] Figure 15 According to Figure 13 The experimental results and linear analysis of the correlation between the obtained thermoelectric voltage and temperature difference show that the output voltage is linearly related to the temperature difference. The slope of this slope is used to calculate the Seebeck coefficient, yielding a Seebeck coefficient S = 4.8 µV / K (formula is...). The power factor is defined as PF = S²σ, which is a performance evaluation parameter for organic thermoelectric materials. The calculated PF is 2.3 μW / (cm·K). 2 ).

[0086] Application examples

[0087] By utilizing its thermoelectric properties and a simple and economical manufacturing process, the polycyclic naphthalene thermoelectric thin film obtained by this invention can be used as a self-powered sensor for various applications.

[0088] The thermoelectric thin film supported by a quartz substrate prepared in Example 1 can be easily transferred onto a flexible polyimide film, making it a wearable temperature sensor. Figure 16 As shown, a polyimide precursor is coated onto a thermoelectric film and amidated. The polyimide is then manually peeled off from the quartz substrate, and the thermoelectric film is transferred onto the polyimide film.

[0089] A ring-shaped wearable temperature sensor was thus fabricated, as shown in the schematic diagram below. Figure 17 As shown in the figure, the same diagram demonstrates the use of this sensor to monitor temperature changes in a beaker containing a mixture of hot water and ice / water at 70°C. By touching the beaker wall with a finger and moving it away, the hot / cold state of the water can be sensed by monitoring the thermoelectric voltage output by the sensor.

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a thermoelectric thin film, characterized in that, Includes the following steps: S1. Modify the surface of the support substrate with metal ions; S2. An organic solution of 3,4,9,10-perylenetetracarboxylic acid is coated onto the surface of the modified metal ion support matrix obtained in step S1 after preheating, and then dried and thermally condensed to form a perylenetetracarboxylic acid dianhydride film. S3. Perform laser direct writing on the perylenetetracarboxylic acid dianhydride film on the support substrate to form a thermoelectric film on the support substrate.

2. The preparation method according to claim 1, characterized in that, In step S1, the room temperature thermal conductivity of the supporting substrate is 1 W / (m·K)-10 W / (m·K), and the coefficient of thermal expansion is 1×10⁻⁶. -7 / ℃-20×10 -7 / ℃, heat resistance temperature greater than 800℃, surface roughness less than 2 nm.

3. The preparation method according to claim 1, characterized in that, In step S1, the method for modifying metal ions is as follows: coating the surface of the support substrate with a solution containing metal salt, and then drying it; The metal ion is one or more of iron ions, aluminum ions and chromium ions; And / or, the amount of metal ions modified on the surface of the supporting substrate is 1×10⁻⁶. -5 mmol / cm 2 -2×10 -5 mmol / cm 2 .

4. The preparation method according to claim 1, characterized in that, In step S2, the concentration of the organic solution of 3,4,9,10-perylenetetracarboxylic acid is 0.05 mmol / L-0.5 mmol / L; And / or, the organic solvent in the organic solution of the 3,4,9,10-perylenetetracarboxylic acid is one or more of dimethyl sulfoxide, N,N-dimethylformamide, chlorobenzene and N-methylpyrrolidone.

5. The preparation method according to claim 1, characterized in that, In step S2, the preheating temperature of the support substrate is 180℃-270℃; the drying time for the drying heat condensation is 1 min-10 min.

6. The preparation method according to claim 1, characterized in that, In step S2, the thickness of the perylenetetracarboxylic acid dianhydride film is 200 nm-800 nm.

7. The preparation method according to claim 1, characterized in that, In step S3, the laser wavelength for the laser direct writing process is 1064 nm-10.64 μm; And / or, the linear energy density of the laser is 20 J / m-40 J / m.

8. A thermoelectric thin film, characterized in that, The thermoelectric thin film is obtained by the preparation method according to any one of claims 1-7.

9. The thermoelectric thin film according to claim 1, characterized in that, The thermoelectric thin film is a polycyclic naphthalene conductive polymer thin film; And / or, the thickness of the thermoelectric thin film is 100 nm-500 nm; And / or, the thermoelectric thin film has a conductivity of 1 s / cm-200 s / cm, a Seebeck coefficient of 1 μV / K-10 μV / K, and a power factor of 0.5 μW / (cm·K). 2 )-10 μW / (cm·K 2 ).

10. A thermoelectric component, characterized in that, Includes the thermoelectric thin film as described in claim 8 or 9.

Images