An organic near-infrared photothermal conversion material, a preparation method and application thereof

Abstract

The application discloses an organic near-infrared light-heat conversion material and a preparation method and application thereof, and belongs to the technical field of light-heat materials. The organic near-infrared light-heat conversion material is prepared through Suzuki coupling reaction and / or Sonogashira coupling reaction, takes 6-(2-ethylhexyl)-[1,2,5]thiadiazole[3,4-F]benzotriazole or benzodithiadiazole as an acceptor core, and is connected with the same or different donor units through a triple bond pi bridge. The organic near-infrared light-heat conversion material has the advantages of simple synthesis method, extended molecular conjugated structure through the introduction of the triple bond pi bridge, enhanced intermolecular interaction, longer sunlight absorption capacity of longer wavelength and excellent light-heat conversion capacity. Under the action of laser and concentrated sunlight, the organic near-infrared light-heat conversion material can reach a high temperature of above 300 DEG C, and has a wide application prospect in the fields of light-heat devices, laser ignition and laser metal processing.

Description

Technical Field

[0001] This invention relates to the field of photothermal materials technology, specifically to an organic near-infrared photothermal conversion material, its preparation method, and its application. Background Technology

[0002] The photothermal effect refers to the property of materials to absorb light energy and release heat energy when irradiated by sunlight or laser light. Photothermal effects not only enable the energy conversion of sunlight but also fully utilize the spatiotemporal controllability of light, finding applications in fields such as biotherapy, seawater desalination, and light-controlled intelligent soft robots. Among the types of photothermal materials, compared to precious metals and inorganic semiconductor photothermal materials, organic photothermal materials are attracting increasing attention from researchers due to their easily tunable structure and properties, and excellent processing performance.

[0003] To improve the photothermal conversion performance of organic photothermal materials, researchers currently focus on the light absorption performance and photothermal conversion efficiency in material development. Traditional organic photothermal materials typically employ large conjugated π-planes or classic donor-acceptor structures to impart absorption properties for long-wavelength light in the solar spectrum (200nm-2500nm). For example, Chinese patent document CN115925641A discloses a DA-structured organic small-molecule photothermal material and its preparation method. This invention uses phthalonitrile as the electron acceptor (A) and diphenylamine as the electron donor (D) to prepare the organic small-molecule photothermal material GDPA-QCN. By enhancing the intermolecular charge transfer brought about by the donor-acceptor structure and prolonging molecular conjugation, it promotes a spectral redshift. However, strategies like this require screening and replacing electron donors and acceptors with more suitable properties, which makes the material preparation method more complex, the structure and performance control more difficult, and ultimately has limited improvement on material performance. Therefore, it is of great significance to develop a simple and universal method to prepare high-efficiency organic photothermal materials, or to further improve the photothermal conversion performance of existing organic photothermal materials through molecular engineering.

[0004] Currently, organic photothermal materials are limited by their light absorption capacity, photothermal conversion performance, and thermal stability, making it difficult to reach very high temperatures under illumination. In common applications such as photothermal therapy and seawater desalination, the photothermal temperature of these materials typically does not exceed 70°C. Recently, a study utilized a [2+2] cycloaddition click reaction to prepare a high-temperature organic near-infrared photothermal material capable of reaching 450°C under an 808nm laser, and explored its applications in laser ignition, metal processing, and high-temperature shape memory (A Processible and Ultrahigh-temperature Organic Photothermal Material through Spontaneous and Quantitative [2+2]Cycloaddition–Cycloreversion, Angew. Chem. Int. Ed. 2024, e202406381). This demonstrates, to some extent, the application value and prospects of organic high-temperature photothermal materials. However, research on such materials is still very limited, the types of materials need further expansion, and high-temperature applications require further exploration. In conclusion, the research and development of organic high-temperature photothermal conversion materials is of great significance. Summary of the Invention

[0005] This invention provides an organic near-infrared photothermal conversion material. This organic near-infrared photothermal conversion material uses 6-(2-ethylhexyl)-[1,2,5]thiadiazole[3,4-F]benzotriazole or benzobisthiadiazole as the acceptor core, and connects the same or different donor units through triple bond π bridges. It has long-wavelength light absorption capability, high molar absorptivity, high photothermal conversion efficiency, and high photothermal conversion temperature, and has broad application prospects in the field of photothermal device fabrication.

[0006] The specific technical solution adopted is as follows:

[0007] An organic near-infrared photothermal conversion material, with the structural formulas shown in formulas (I) to (IV):

[0008]

[0009] In formulas (I) to (IV), the donor units D1 and D2 are phenyl groups substituted with alkylamine, aromaticamine or heteroarylamine groups.

[0010] Preferably, the donor units D1 and D2 are each independently selected from one of the following formulas, where D1 and D2 may be the same or different;

[0011]

[0012] Where n is any integer from 1 to 10, R is hydrogen, fluorine, cyano, methoxy or C1 to C10 alkyl, and * indicates the substitution position.

[0013] The present invention also provides a method for preparing the organic near-infrared photothermal conversion material, including method one or method two;

[0014] Method 1 includes the following steps:

[0015] S01 is prepared by a Suzuki coupling reaction of a dihalogenated acceptor nuclear compound and a donor compound substituted with boric acid or borate ester at a molar ratio of 1:1.2 to 1.5 to obtain intermediate 1;

[0016] SO2 uses intermediate 1 and an alkynyl-substituted donor compound as raw materials to undergo a Sonogashira coupling reaction at a molar ratio of 1:1.2 to 1.5 to obtain an organic near-infrared photothermal conversion material with the structural formula shown in formula (I) or formula (III).

[0017] Method 2 includes the following steps:

[0018] S11 uses a dihalogenated acceptor nuclear compound and an alkynyl-substituted donor compound as raw materials, and undergoes a Sonogashira coupling reaction at a molar ratio of 1:2.2 to 2.5 to obtain an organic near-infrared photothermal conversion material with the structural formula shown in (II) or (IV).

[0019] Specifically, the structural formula of the dihalogenated acceptor nuclear compound is as follows: Where X is Cl, Br or I.

[0020] In Method 1, the structural formula of the donor compound substituted with boric acid or borate ester is as follows: The structural formula of the alkynyl-substituted donor compound is The definitions of D1 and D2 are the same as above.

[0021] In Method 2, the structural formula of the alkynyl-substituted donor compound is: and The definitions of D1 and D2 are the same as above.

[0022] Preferably, the conditions for the Suzuki coupling reaction are 60–120°C for 10–24 h.

[0023] Preferably, the conditions for the Sonogashira coupling reaction are 60–100 °C for 10–24 h.

[0024] This invention also provides the application of the aforementioned organic near-infrared photothermal conversion material in the fields of solar energy conversion, solar energy storage, laser ignition, laser metal processing, or light-controlled shape memory material processing.

[0025] This invention also provides a solar photothermal conversion device, comprising a photothermal coating made of the aforementioned organic near-infrared photothermal conversion material. This organic near-infrared photothermal conversion material possesses long-wavelength light absorption capability, a high molar absorptivity, and strong photothermal conversion capability. The resulting photothermal coating exhibits excellent performance, and the further fabricated solar photothermal conversion device has broad application prospects in the field of solar energy conversion and utilization.

[0026] This invention also provides a concentrated solar energy molten inorganic salt thermal storage device, comprising a photothermal coating made of the aforementioned organic near-infrared photothermal conversion material. Based on its excellent photothermal conversion performance and superior thermal stability under outdoor sunlight, the photothermal coating made of this organic near-infrared photothermal conversion material can reach a high photothermal conversion temperature of over 300°C under outdoor concentrated sunlight irradiation, thereby causing the inorganic salt loaded on the coating to melt and converting solar energy into the phase transition enthalpy of the molten inorganic salt, thus achieving solar energy storage.

[0027] In addition, this organic near-infrared photothermal conversion material, based on its high photothermal conversion temperature, also has broad application prospects in fields such as photo-controlled metal processing and photo-controlled high-temperature shape memory.

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

[0029] (1) The method for synthesizing organic near-infrared photothermal conversion materials provided by the present invention is simple, the raw materials are readily available, the yield is high, and it is easy to prepare in large quantities. Moreover, the organic near-infrared photothermal conversion materials have a stable structure and a high thermal decomposition temperature.

[0030] (2) In the traditional donor-acceptor structure organic molecule, the present invention uses a triple bond as a π bridge between the donor unit and the acceptor unit, which extends the molecular conjugation and enhances the intermolecular interaction, thus significantly improving the light absorption capacity and photothermal conversion performance of the material.

[0031] (3) The organic near-infrared photothermal conversion material prepared by this invention has excellent solar photothermal conversion capability. On the one hand, it can be applied to solar-driven photothermal-electric conversion applications with high conversion efficiency; on the other hand, the material can reach a high temperature of over 300°C under concentrated sunlight, which is sufficient to achieve long-distance ignition of combustibles, processing of low-melting-point metals, and melting of some inorganic salts. It has broad application prospects in the fields of solar energy conversion and storage, laser ignition, laser metal processing, or optically controlled shape memory material processing. Attached Figure Description

[0032] Figure 1 The image shows the 1H NMR spectrum of the organic near-infrared photothermal conversion material prepared in Example 1 in deuterated dichloromethane.

[0033] Figure 2The image shows the UV-Vis-NIR absorption curves of the organic near-infrared photothermal conversion material solid powder prepared in Example 1.

[0034] Figure 3 This is a statistical chart showing the highest photothermal temperature of the organic near-infrared photothermal conversion material prepared in Example 1 under different power densities of 808nm lasers.

[0035] Figure 4 The image shows the 1H NMR spectrum of the organic near-infrared photothermal conversion material prepared in Example 4 in deuterated dichloromethane.

[0036] Figure 5 The image shows the UV-Vis-NIR absorption curves of the organic near-infrared photothermal conversion material solid powder prepared in Example 4.

[0037] Figure 6 This is a statistical chart showing the highest photothermal temperature of the organic near-infrared photothermal conversion material prepared in Example 4 under different power densities of 808nm lasers.

[0038] Figure 7 The photothermal conversion curve of the organic near-infrared photothermal conversion material prepared in Example 4 is shown under simulated sunlight.

[0039] Figure 8 The voltage variation curves of the solar photothermal-electric conversion device prepared in Example 1 under different simulated solar power are shown.

[0040] Figure 9 The temperature change curves of the concentrated solar molten inorganic salt thermal storage device prepared in Example 4 are shown with and without inorganic salt load. Detailed Implementation

[0041] The present invention will be further illustrated below with reference to the embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically described in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art.

[0042] Example 1

[0043] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTAyA) is shown below:

[0044]

[0045] The synthesis route is as follows:

[0046]

[0047] (1) Weigh the dihalogenated acceptor nuclear compound a (447 mg, 1 mmol), the boric acid-substituted donor compound b (347 mg, 1.2 mmol), K₂CO₃ (829 mg, 6 mmol), and Pd(PPh₃)₄ (58 mg, 0.05 mmol) into a 100 mL double-necked flask. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 6 mL of tetrahydrofuran and 3 mL of deionized water to a single-necked flask and purge with nitrogen for 30 min to purge the air from the solvent. Subsequently, use a syringe to add the reagents from the flask to the double-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain intermediate c powder with a yield of 63%.

[0048] (2) Weigh intermediate c (305 mg, 0.5 mmol), alkynyl-substituted donor compound d (161 mg, 0.6 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 50 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 3 mL of ultra-dry tetrahydrofuran and 3 mL of ultra-dry triethylamine to the reaction flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a blue-black powder BTAyA with a yield of 80%.

[0049] Example 2

[0050] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTMyM) is as follows:

[0051]

[0052] The synthesis route is as follows:

[0053]

[0054] (1) Weigh the dihalogenated acceptor nuclear compound a (447 mg, 1 mmol), the boric acid-substituted donor compound b (198 mg, 1.2 mmol), K₂CO₃ (829 mg, 6 mmol), and Pd(PPh₃)₄ (58 mg, 0.05 mmol) into a 100 mL double-necked flask. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 6 mL of tetrahydrofuran and 3 mL of deionized water to a single-necked flask and purge the solvent with nitrogen for 30 min to purge the air from the solvent. Subsequently, use a syringe to add the reagents from the flask to the double-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain intermediate c, with a yield of 69%.

[0055] (2) Weigh intermediate c (244 mg, 0.5 mmol), alkynyl-substituted donor compound d (87 mg, 0.6 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 50 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 3 mL of ultra-dry tetrahydrofuran and 3 mL of ultra-dry triethylamine to the reaction flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a black powder BTMyM with a yield of 73%.

[0056] Example 3

[0057] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTCzyCz) is shown below:

[0058]

[0059] The synthesis route is as follows:

[0060]

[0061] (1) Weigh the dihalogenated acceptor nuclear compound a (447 mg, 1 mmol), the boric acid-substituted donor compound b (344 mg, 1.2 mmol), K₂CO₃ (829 mg, 6 mmol), and Pd(PPh₃)₄ (58 mg, 0.05 mmol) into a 100 mL double-necked flask. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 6 mL of tetrahydrofuran and 3 mL of deionized water to a single-necked flask and purge with nitrogen for 30 min to purge the air from the solvent. Subsequently, use a syringe to add the reagents from the flask to the double-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain intermediate c powder with a yield of 78%.

[0062] (2) Weigh intermediate c (304 mg, 0.5 mmol), alkynyl-substituted donor compound d (160 mg, 0.6 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 50 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Vacuum the system three times using a double-row tube to purge the air from the flask. Then, add 3 mL of ultra-dry tetrahydrofuran and 3 mL of ultra-dry triethylamine to the reaction flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a dark blue powder BTCzyCz with a yield of 75%.

[0063] Example 4

[0064] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTDyA) is shown below:

[0065]

[0066] The synthesis route is as follows:

[0067]

[0068] Weigh the dihalogenated acceptor compound a (447 mg, 1 mmol), the alkynyl-substituted donor compound b (673 mg, 2.5 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 100 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Evacuate the system three times using a double-row tube and purge with nitrogen to remove air from the flask. Then, add 6 mL of ultra-dry tetrahydrofuran and 6 mL of ultra-dry triethylamine to a 100 mL single-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a blue-black powder BTDyA in 71% yield.

[0069] Example 5

[0070] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTDyCz) is shown below:

[0071]

[0072] The synthesis route is as follows:

[0073]

[0074] Weigh the dihalogenated acceptor compound a (447 mg, 1 mmol), the alkynyl-substituted donor compound b (668 mg, 2.5 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 100 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Evacuate the system three times using a double-row tube and purge with nitrogen to remove air from the flask. Then, add 6 mL of ultra-dry tetrahydrofuran and 6 mL of ultra-dry triethylamine to a 100 mL single-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a blue-black powder BTDyCz in 67% yield.

[0075] Example 6

[0076] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BTDyPT) is shown below:

[0077]

[0078] The synthesis route is as follows:

[0079]

[0080] Weigh the dihalogenated acceptor compound a (447 mg, 1 mmol), the alkynyl-substituted donor compound b (748 mg, 2.5 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 100 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Evacuate the system three times using a double-row tube and purge with nitrogen to remove air from the flask. Then, add 6 mL of ultra-dry tetrahydrofuran and 6 mL of ultra-dry triethylamine to a 100 mL single-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a black powder BTDyPT in 68% yield.

[0081] Example 7

[0082] In this embodiment, the structural formula of the prepared organic near-infrared photothermal conversion material (BBTDyA) is shown below:

[0083]

[0084] The synthesis route is as follows:

[0085]

[0086] Weigh the dihalogenated acceptor compound a (352 mg, 1 mmol), the alkynyl-substituted donor compound b (673 mg, 2.5 mmol), Pd(PPh3)4 (23 mg, 0.02 mmol), and CuI (8 mg, 0.04 mmol) into a 100 mL double-necked flask equipped with a magnetic ferrule. Seal the narrow neck of the flask with a rubber stopper and connect the wide neck to a reflux condenser. Evacuate the system three times using a double-row tube and purge with nitrogen to remove air from the flask. Then, add 6 mL of ultra-dry tetrahydrofuran and 6 mL of ultra-dry triethylamine to a 100 mL single-necked flask and react at 80 °C for 12 h. After the reaction is complete, extract the reaction system with dichloromethane and deionized water, and evaporate to dryness. Purify and separate the crude product using silica gel column chromatography to obtain a blue-black powder BBTDyA in 45% yield.

[0087] Application Example 1

[0088] This application example uses the organic near-infrared photothermal conversion material obtained in the previous examples as a raw material to prepare a solar photothermal conversion device. Taking BTDyA obtained in Example 4 as an example, the device preparation method for other materials is the same. The specific preparation method is as follows:

[0089] BTDyA (50 mg) and commercially available polymethyl methacrylate (500 mg) were completely dissolved in dichloroethane. The mixture was then drop-coated onto a bismuth telluride semiconductor thermoelectric device (commercially available). After the solvent had completely evaporated, a photothermal conversion device with a photothermal coating was obtained.

[0090] Application Example 2

[0091] This application example uses the organic near-infrared photothermal conversion material obtained in the previous examples as a raw material to prepare a concentrated solar molten inorganic salt thermal storage device. Taking BTDyA obtained in Example 4 as an example, the device preparation method for other materials is the same. The specific preparation method is as follows:

[0092] BTDyA (50 mg) was melted and processed onto a quartz plate (1 cm × 1 cm) to obtain a photothermal conversion device with a photothermal coating. Subsequently, a mixed inorganic salt of sodium nitrate and potassium nitrate was placed on the photothermal conversion device. The device was also equipped with a plano-convex lens to focus sunlight.

[0093] Sample Analysis

[0094] Taking the organic near-infrared photothermal conversion materials BTAyA and BTDyA prepared in Examples 1 and 4 as examples, their proton NMR spectra in deuterated dichloromethane are shown below. Figure 1 and Figure 4 As shown, this demonstrates the successful synthesis of the organic near-infrared photothermal conversion material.

[0095] The UV-Vis-NIR absorption spectrum of BTAyA powder is as follows: Figure 2 As shown in the figure, its absorption spectrum covers the entire ultraviolet-visible light band and extends into the near-infrared region. The ultraviolet-visible-near-infrared absorption spectrum of BTDyA powder is as follows: Figure 5 As shown in the figure, its absorption spectrum covers the entire ultraviolet-visible band and can be further extended to more than 1500nm in the near-infrared region, demonstrating excellent solar spectral absorption capabilities.

[0096] The statistical graph of the highest photothermal temperature of BTAyA powder at different power densities of an 808nm laser is shown below. Figure 3 As shown in the figure, the BTAyA solid material achieves a power density of 1.4 W / cm². -2 Under an 808nm laser, the maximum photothermal temperature can reach 300℃. The statistical graph of the maximum photothermal temperature of BTDyA powder under different power densities of an 808nm laser is shown below. Figure 6 As shown in the figure, the BTDyA solid-state material achieves a power density of 2.0 W / cm². -2 With an 808nm laser, the maximum photothermal temperature can reach 370℃.

[0097] The photothermal conversion curve of BTDyA powder under simulated sunlight is shown below. Figure 7 As shown in the figure, BTDyA powder at a power density of 100 mW / cm³ exhibits [performance / results]. -2 Under simulated sunlight, the maximum photothermal temperature can reach 50℃.

[0098] The voltage-time curve of BTDyA when applied to solar photothermal conversion is shown below. Figure 8 As shown in the figure, the fabricated solar-thermal-electric conversion device achieves a power density of 100 mW / cm². -2 Under simulated sunlight, the open-circuit voltage can reach 90mV.

[0099] The temperature-time curve of BTDyA applied to a concentrated solar molten inorganic salt thermal storage device is shown below. Figure 9 As shown in the figure, without inorganic salt loading (control group), the material can reach a high temperature of 320℃ under concentrated sunlight. After loading inorganic salt, a clear inorganic salt melting and heat storage stage can be observed during the photothermal heating phase; while during the cooling phase after the light irradiation stops, the slow release of heat energy due to the presence of molten inorganic salt is clearly visible. These applications demonstrate the promising application prospects of this organic near-infrared photothermal conversion material in solar molten salt thermal energy storage.

[0100] In summary, this invention prepares a highly efficient organic near-infrared photothermal conversion material by introducing triple bonds as π-bridges into traditional donor-acceptor organic materials. This material possesses advantages such as broad-spectrum absorption, strong thermal stability, and a high photothermal conversion temperature. Based on this material, this invention further develops a concentrated solar molten inorganic salt thermal storage device, which exhibits excellent performance and holds promise for applications in solar energy storage and utilization. Furthermore, this material also demonstrates excellent performance and results in the field of solar photothermal-electric conversion. In conclusion, the organic near-infrared photothermal conversion material prepared by this invention exhibits excellent performance and broad application prospects.

[0101] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An organic near-infrared photothermal conversion material, characterized in that, The structural formulas are shown in equations (I) to (IV): In equations (I) to (IV), the donor units D1 and D2 are each independently selected from one of the following equations, and D1 and D2 may be the same or different; Where n is any integer from 1 to 10, R is hydrogen, fluorine, cyano, methoxy or C1 to C10 alkyl, and * indicates the substitution position.

2. The method for preparing the organic near-infrared photothermal conversion material according to claim 1, characterized in that, This includes either Method 1 or Method 2; Method 1 includes the following steps: S01 is prepared by a Suzuki coupling reaction of a dihalogenated acceptor nuclear compound and a donor compound substituted with boric acid or borate ester at a molar ratio of 1:1.2 to 1.5 to obtain intermediate 1; SO2 uses intermediate 1 and an alkynyl-substituted donor compound as raw materials to undergo a Sonogashira coupling reaction at a molar ratio of 1:1.2 to 1.5 to obtain an organic near-infrared photothermal conversion material with the structural formula shown in formula (I) or formula (III). Method 2 includes the following steps: S11 uses a dihalogenated acceptor nuclear compound and an alkynyl-substituted donor compound as raw materials, and undergoes a Sonogashira coupling reaction at a molar ratio of 1:2.2 to 2.5 to obtain an organic near-infrared photothermal conversion material with the structural formula shown in (II) or (IV). The structural formula of the dihalogenated acceptor nuclear compound is as follows: Where X is Cl, Br, or I; In Method 1, the structural formula of the donor compound substituted with boric acid or borate ester is as follows: The structural formula of the alkynyl-substituted donor compound is In Method 2, the structural formula of the alkynyl-substituted donor compound is: The definitions of D1 and D2 are the same as above.

3. The method for preparing the organic near-infrared photothermal conversion material according to claim 2, characterized in that, The conditions for the Suzuki coupling reaction are 60–120 °C for 10–24 h.

4. The method for preparing the organic near-infrared photothermal conversion material according to claim 2, characterized in that, The conditions for the Sonogashira coupling reaction are 60–100 °C for 10–24 h.

5. The application of the organic near-infrared photothermal conversion material according to claim 1 in the fields of solar energy conversion, solar energy storage, laser ignition, laser metal processing, or optically controlled shape memory material processing.

6. A solar photothermal conversion device, characterized in that, Photothermal coatings made from the organic near-infrared photothermal conversion material as described in claim 1.

7. A concentrating solar molten inorganic salt thermal storage device, characterized in that, Photothermal coatings made from the organic near-infrared photothermal conversion material as described in claim 1.

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