Organic photo-thermal material and preparation method and application thereof

Abstract

The invention relates to the technical field of photo-thermal materials, in particular to an organic photo-thermal material and a preparation method and application thereof. The organic photo-thermal material disclosed by the invention can realize efficient solar thermal conversion, provides potential possibility for water purification and power supply due to the potential shown in the field of efficient utilization of solar energy, and is beneficial to sustainable development of green energy.

Description

Technical Field

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

[0002] Energy is a fundamental element driving social progress and economic growth; however, with the rapid development of human society, the problem of energy shortage has become increasingly serious. Excessive consumption of non-renewable energy sources will lead to resource depletion, energy security risks, and economic vulnerability, further exacerbating environmental pollution and climate change. To address this dilemma, solar energy, as a new type of green and renewable energy, has significant advantages such as abundant resources, wide distribution, environmental friendliness, and strong sustainability, and can effectively replace traditional fossil fuels to reduce air pollution. Photothermal conversion, as an effective method of converting light energy into heat energy, can be applied to many fields such as seawater desalination and solar power generation. In particular, the emerging interfacial water evaporation technology based on solar thermal conversion significantly improves water evaporation efficiency, becoming a highly efficient and low-energy-consumption solution for obtaining freshwater from seawater or wastewater to address the global freshwater shortage problem. Furthermore, by utilizing the synergistic effect of solar thermal conversion and the Seebeck effect, light-heat-electricity conversion is achieved, demonstrating enormous potential in the development and efficient utilization of solar energy.

[0003] Currently, research on photothermal conversion materials mainly focuses on inorganic materials, including metal nanostructures, transition metal sulfides and oxides (such as MoS2, TiO2, Fe3O4), carbon-based amorphous materials (such as graphene and carbon nanotubes), and ceramic materials such as metal silicides and borides. However, some limitations exist in practical applications. Some inorganic materials have a narrow light absorption range, typically only absorbing specific wavelengths of light, resulting in low utilization of the solar spectrum. Secondly, some inorganic photothermal materials lack thermal stability, easily undergoing structural changes or performance degradation under high temperatures or long-term illumination. Furthermore, the preparation process of inorganic materials is often complex and costly, limiting their large-scale application. In contrast, organic small-molecule photothermal materials have advantages such as high structural tunability, strong processing feasibility, and good flexibility. They convert near-infrared (NIR) light into heat energy through non-radiative decay, and have recently become an increasingly important research subject in the biomedical field. However, their utilization in other solar energy applications has not attracted much research attention. This is mainly due to concerns that their poor photobleaching properties and limited sunlight absorption will lead to inefficient solar photothermal conversion. Therefore, researching and exploring organic small-molecule photothermal materials with strong light absorption capacity, high photothermal conversion efficiency, and good photochemical / photothermal stability is the key to achieving efficient utilization of solar energy. Summary of the Invention

[0004] The purpose of this invention is to provide a novel small-molecule photothermal material based on the interaction between electron acceptors and donors. This material, by introducing free radical groups to suppress radiative transitions, further broadens the absorption range and improves photothermal conversion capabilities. This invention is achieved through the following technical solution: On the one hand, the present invention provides a small molecule photothermal material, which is a compound as shown in formula (I), or a stereoisomer or geometric isomer of the compound shown in formula (I): (I); in: T is O, S, or Se; L1 and L2 are each independently a direct bond or a 5-8 heteroaryl group, wherein the 5-8 heteroaryl group may optionally be bonded by 1, 2, or 3 atoms selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl and C 1-6 Substituents of haloalkoxy groups; R1 is C 3-15 Alkyl or C 3-8 cycloalkyl, the C 3-15 Alkyl and C 3-8 The cycloalkyl group may optionally be surrounded by one, two, or three atoms selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl and C 1-6 Substituents of haloalkoxy groups; R2, R3, R4, and R5 are respectively H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl and C 1-6 The alkoxy group is a haloalkoxy group, and at least two of R2, R3, R4, and R5 are OH; R6 and R7 are independently H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C, respectively. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl and C 1-6 Halogenated alkoxy groups.

[0005] In some implementations, L1 and L2 are independently direct bonds, , , , , The above substituents may optionally be replaced by 1, 2 or 3 substituents selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3 and -OCH2CF2CHF2.

[0006] In some implementations, R1 is , , , , , Cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; the above substituents may optionally be replaced by 1, 2, or 3 substituents selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3, and -OCH2CF2CHF2.

[0007] In some embodiments, R6 and R7 are independently H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3, and -OCH2CF2CHF2.

[0008] In some implementations, L1 and L2 are both direct keys; or L1 and L2 are both... or .

[0009] In some embodiments, it is a compound having one of the following structures or a stereoisomer or geometric isomer of a compound having one of the following structures: , , , , , , , , or .

[0010] On the other hand, the present invention also protects the preparation method of the above-mentioned organic photothermal material, characterized by comprising the following steps: Step 1: Compound 1 and Compound 2 undergo a coupling reaction in the presence of a base and a Pd catalyst to generate Compound 3; Step 2: Compound 3 undergoes a demethylation reaction with BBr3 to produce the compound shown in formula (I); Among them, R8, R9, R 10 R 11 The independent components are H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C, respectively. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl and C 1-6 The alkoxy group is a haloalkoxy group, and at least two of R2, R3, R4, and R5 are carbon atoms. 1-6 Alkoxy; The reaction route is as follows: .

[0011] In some embodiments, the base in step 1 is selected from one or more of potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium hydroxide, and sodium hydroxide; the Pd catalyst is selected from one or more of Pd(PPh3)4, Pd(PPh3)2Cl2, and Pd(dppf)Cl2.

[0012] In some embodiments, the present invention also protects the application of the above-mentioned organic photothermal materials in solar energy conversion or solar energy storage.

[0013] In some embodiments, the present invention also protects the application of the above-mentioned organic photothermal materials in the fields of seawater desalination or solar photothermal power.

[0014] The present invention has achieved the following beneficial effects: 1) In this invention, near-infrared molecules TBT-TPA-OMe and TBT-T-TPA-OMe with DA-type molecular structures are first prepared, and then the methoxy molecules are demethylated to convert them into open-shell phenoxy radical molecules TBT-TPA-O and TBT-T-TPA-O.

[0015] 2) Compared with methoxy precursor materials, the free radical organic photothermal material prepared by this invention exhibits a significantly wider absorption range and better photothermal performance, achieving optimal absorption at 1.1 W / cm² on an 808 nm laser. -2 Under irradiation power, the temperature can rise to 225°C within 60 seconds and remain stable even after repeated cycles.

[0016] 3) The organic photothermal material of this invention is incorporated into polyurethane (PU) foam for solar-driven interfacial water evaporation. It exhibits a evaporation rate of 1.356 kg m³ under a single solar irradiation. −2 h −1 It exhibits a high water evaporation rate and a solar water evaporation efficiency of 93.05%. In other high-efficiency solar energy thermoelectric simulation applications, it achieves excellent open-circuit voltage (0.245 V) and output power density (3.936 W·m) at one solar irradiance. -2 ).

[0017] 4) The organic photothermal material of the present invention can achieve efficient solar thermal conversion. Its potential in the field of efficient utilization of solar energy provides potential for water purification and power generation, and contributes to the sustainable development of green energy.

[0018] Unless otherwise stated, the following definitions will apply in this invention. For the purposes of this invention, chemical elements are defined according to the periodic table, CAS version, and the Chemical Handbook, 75th Ed, 1994. Furthermore, general principles of organic chemistry are found in "Organic Chemistry," Thomas Sorrell, University Science Books, Sausalito: 1999, and "March's Advanced Organic Chemistry," by Michael B. Smith and Jerry March, John Wiley & Sons, New York: 2007; therefore, all content incorporates these references.

[0019] The term "alkyl" as used in this invention includes a monovalent hydrocarbon group with 1-20 carbon atoms, or 1-10 carbon atoms, or 1-6 carbon atoms, or 1-4 carbon atoms, or 1-3 carbon atoms, or 1-2 carbon atoms, consisting of a saturated straight-chain or branched chain, wherein the alkyl group may be independently and optionally substituted by one or more substituents described in this invention. Further examples of alkyl groups include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), n-propyl (n-Pr, -CH2CH2CH3), isopropyl (i-Pr, -CH(CH3)2), n-butyl (n-Bu, -CH2CH2CH2CH3), isobutyl (i-Bu, -CH2CH(CH3)2), sec-butyl (s-Bu, -CH(CH3)CH2CH3), tert-butyl (t... -Bu, -C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl -1-Butyl (-CH2CH(CH3)CH2CH3), n-Hexyl (-CH2CH2CH2CH2CH2CH3), 2-Hexyl (-CH(CH3)CH2CH2CH2CH3), 3-Hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-Methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-Methyl-2-pentyl (-CH(CH3)CH(CH3)CH2C) H3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3), n-heptyl, and n-octyl, etc. The term "alkyl" and its prefix "alkane" are used here, both encompassing straight-chain and branched saturated carbon chains.

[0020] The term "alkoxy" or "alkyloxy" as used in this invention refers to an alkyl group, as defined herein, that is attached to other parts of a compound molecule via an oxygen atom. In some embodiments, the alkoxy group is C10. 1-4 Alkoxy groups; examples of which include, but are not limited to, methoxy, ethoxy, propoxy, and butoxy groups. Furthermore, the alkoxy group may be independently unsubstituted or substituted by one or more substituents described in this invention.

[0021] The term "cycloalkyl" refers to a monovalent or polyvalent monocyclic, bicyclic, or tricyclic carbocyclic system containing 3-12 carbon atoms, which is a saturated ring or a ring containing one or more unsaturated bonds, but never an aromatic ring. In one embodiment, the cycloalkyl group contains 3-10 carbon atoms; in another embodiment, it contains 3-8 carbon atoms; and in yet another embodiment, it contains 3-6 carbon atoms. Examples of such groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclohexenyl. The cycloalkyl group may be independently unsubstituted or substituted by one or more substituents described in this invention.

[0022] A ring system formed by a substituent connected to a ring by a bond means that the substituent can be substituted at any substituted position on the ring. For example, formula (a) means that the substituent R can be monosubstituted or polysubstituted at any possible substituted position on the pyridine ring.

[0023] Unless otherwise explicitly stated, the descriptive phrases “each and each is independently”, “each and each is independently”, and “each and each is independently” used throughout this document are interchangeable and should be interpreted broadly. They can mean either that the specific options expressed by the same symbols in different groups do not affect each other, or that the specific options expressed by the same symbols in the same group do not affect each other.

[0024] Unless otherwise indicated, the structural formulas described in this invention include all isomers (e.g., enantiomers, diastereomers, geometric isomers, or conformational isomers): for example, R and S configurations containing an asymmetric center, (Z) and (E) isomers of double bonds, and (Z) and (E) conformational isomers. Therefore, any single stereochemical isomer of the compounds of this invention, or a mixture of its enantiomers, diastereomers, geometric isomers, or conformational isomers, is within the scope of this invention.

[0025] Unless otherwise stated herein or the context clearly indicates otherwise, the terms “an,” “a,” “the,” and similar terms used herein, as well as in the context of the invention (especially in the context of the claims), may be interpreted as including both the singular and the plural. Attached Figure Description

[0026] Figure 1 For compound TBT-TPA-O 1 H NMR spectrum; Figure 2 For compound TBT-T-TPA-O 1 H NMR spectrum; Figure 3 The optical performance correlation spectrum is shown, among which, Figure 3a represents four different molecular states: powder and solution. Figure 3 b represents the absorption signals of four different molecular films; Figure 3 c shows the absorption spectra of four different molecules in tetrahydrofuran solution; Figure 4 d represents the electron spin resonance spectra of four different solid powders; Figure 4 The graph shows the correlation between photothermal performance, where... Figure 4 a represents TBT-T-TPA-O powder irradiated with an 808 nm laser (1.1 W / cm²). 2 Infrared (IR) thermal images with and without infrared (IR) imaging. Figure 4 b-4e consists of TPA-TPA-OMe and TPA-TPA-O powders (5 mg) at different laser powers (0.3–1.5 W / cm²). 2 Photothermal conversion behavior under 808 nm laser irradiation; Figure 4 f represents TBT-T-TPA-O powder under 808 nm laser light (1.1 W / cm²). 2 Temperature change curve after 11 switching cycles under irradiation; Figure 5 Digital photographs of PU with different molecular loads, and SEM images of pure PU and molecularly loaded PU foams; Figure 6 The relevant spectra for the photothermal evaporation water simulation seawater desalination test are shown in the following figures. Figure 6 a is a TBT-T-TPA-O+PU dry foam that simulates 1 kW / m² of sunlight in air. 2 Temperature-time curve at time; Figure 6 b represents the simulated solar radiation intensity of TBT-T-TPA-O foam in water as 1 kW / m². 2 Temperature-time curve at time; Figure 6 c represents the ion concentration (Na+) of the South China Sea before and after desalination. + Mg 2+ Ca 2+ and K + Changes in ) Figure 6 d represents pure PU and PU with loaded molecules under simulated solar radiation intensity of 1 kW / m². 2 Evaporation curve at time; Figure 6 e represents the solar evaporator in simulated seawater, 1 kW / m 2 Water quality change curves under five cycles of light intensity; Figure 6 f represents the evaporation rate and conversion efficiency of different types of photothermal materials.

[0027] Figure 7 The graphs show the thermoelectric conversion performance, where... Figure 7a and 7b represent the conditions under standard solar irradiance (1 kW / m²). 2 The thermoelectric conversion capability of thermoelectric devices under voltage and current changes; Figure 7 c represents the standard solar irradiance (1 kW / m²). 2 The thermoelectric conversion capability of thermoelectric devices under power changes; Figure 7 d represents the thermoelectric power generation performance stability of TBT-T-TPA-OMe and TBT-T-TPA-O through 5 switching cycles; Figure 7 e simulates the rotation of fan blades driven by sunlight under the thermoelectric effect; Figure 7 f represents the use of multiple thermoelectric devices connected in series to drive the fan rotation under actual outdoor conditions.

[0028] Figure 8 The relevant graphs for testing combined hydropower capacity include, Figure 8 a represents the temperature change of the PU surface loaded with TBT-T-TPA-O molecules (5 mg) under different solar radiation intensities; Figure 8 b shows the temperature comparison between the PU loaded with TBT-T-TPA-O molecules (5 mg) on ​​the surface of the thermoelectric device and the water surface after 10 minutes of irradiation under different sunlight intensities. Figure 8 c represents the thermoelectric conversion capability of loading TBT-T-TPA-O molecules (5 mg) under different solar radiation intensities; Figure 8 d represents the water evaporation curve of the water-power cogeneration unit under standard sunlight. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0030] The endpoints and any values ​​of the ranges described in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The raw materials and reagents used in the following examples are commercially available.

[0031] , 4,8-Dibromo-6-(2-ethylhexyl)-[1,2,5]thiadiazo[3,4-F]benzotriazole (0.447 mmol, 200 mg) and (4-(bis(4-methoxyphenyl)amino)phenyl)boronic acid (1.12 mmol, 390 mg) were added to a 20 mL mixture of THF (12 mL) and water (8 mL) containing 650 mg of dry K₂CO₃. Subsequently, under a nitrogen atmosphere, a catalyst of [1,1′-bis(diphenylphosphine)ferrocene]dichloropalladium (22.3 × 10⁻³ mmol, 16.3 mg) was added at room temperature. The mixture was then heated to 85 °C and stirred overnight. After cooling to room temperature, the reaction mixture was extracted with chloroform. The target compound was purified by silica gel column chromatography (dichloromethane / hexane = 1.5:1) after concentration under reduced pressure. Yield: (300 mg, 75%).

[0032] Step 2: Preparation of compound TBT-TPA-O , TBA-TPA-OMe (100 mg, 0.11 mmol) was dissolved in 10 mL of anhydrous dichloromethane. Under nitrogen protection, the precursor was placed in a cold trap and cooled to -78 °C with ethanol. Then, 3 mL of 1 M BBr3 solution was added dropwise under nitrogen protection. After stirring at room temperature for 12 h, a solid product precipitated. Subsequently, methanol was added dropwise to the reaction solution to terminate the BBr3 reaction. The reaction solution was added dropwise to deionized water, the solid was separated by filtration, and the crude product was purified by washing with water and dichloromethane sequentially. Thin-layer chromatography (TLC) using dichloromethane as the eluent showed no impurities, indicating complete demethylation. The product was vacuum dried at 60 °C for 24 h to obtain black TBT-TPA-O powder, yield: (81 mg, 86.41%).

[0033] 1 H NMR (500 MHz, DMSO- d 6) δ 9.42 (d, J = 36.9 Hz, 4H), 8.22 (d, J =8.7 Hz, 2H), 7.05 (dd, J = 22.0, 8.7 Hz, 10H), 6.81 (td, J = 13.7, 9.2 Hz, 12H), 4.88 – 4.66 (m, 2H), 2.32 – 2.09 (m, 1H), 1.28 (dd, J = 42.9, 7.5 Hz, 8H), 0.90 (t, J = 7.2 Hz, 3H), 0.80 (t, J = 7.3 Hz, 3H).

[0034] ,

[0035] 4,8-Dibromo-6-(2-ethylhexyl)-[1,2,5]thiadiazo[3,4-f]benzotriazole (500 mg, 1.12 mmol) and tributyl-(2-thienyl)stanane (1.21 g, 3.24 mmol) were dissolved in dry anhydrous toluene (PhMe, 25 mL). Then, bis(triphenylphosphine)palladium chloride (Pd(PPh3)4Cl2, 68 mg) was added, and the mixture was purged with argon for 15 min. The reaction mixture was heated to 120 °C and stirred overnight. After cooling to room temperature, the reaction mixture was washed successively with aqueous potassium fluoride solution, water, and saturated brine, and extracted with chloroform. After concentration under reduced pressure, the residue was purified by silica gel column chromatography to give a dark blue powder, yield: 466.6 mg, 92%.

[0036] Step 2: Synthesis of Compound 3 Compound 2 (500 mg, 1.10 mmol) was dissolved in tetrahydrofuran (THF) (15 mL). Then, a THF solution (20 mL) of N-bromosuccinimide (NBS) (411.97 mg, 2.31 mmol) was added dropwise, and the mixture was stirred overnight at room temperature. After concentration under reduced pressure, the residue was purified by silica gel column chromatography to give the target compound as a dark blue powder, yield: (636.5 mg, yield: 91.2%).

[0037] Compound 3 (300 mg, 0.491 mmol) and (4-(bis(4-methoxyphenyl)amino)phenyl)boronic acid (498 mg, 1.43 mmol) were added to a 20 mL mixture of THF (12 mL) and water (8 mL) containing 680 mg of dry K₂CO₃. Subsequently, under a nitrogen atmosphere, a catalyst of [1,1′-bis(diphenylphosphine)ferrocene]dichloropalladium (24.5 × 10⁻³ mmol, 17.9 mg) was added at room temperature. The mixture was then heated to 85 °C and stirred overnight. After cooling to room temperature, the reaction mixture was extracted with chloroform. The solution was concentrated under reduced pressure and purified by silica gel column chromatography (dichloromethane / hexane = 1.5:1) to give the target blue compound. Yield: (411 mg, 79%).

[0038] TBA-T-TPA-OMe (100 mg, 0.094 mmol) was dissolved in 10 mL of anhydrous dichloromethane. Under nitrogen protection, the precursor was placed in a cold trap and cooled to -78 °C with ethanol. Then, 3 mL of 1 M BBr3 solution was added dropwise under nitrogen protection. After stirring at room temperature for 12 h, a solid product precipitated. Subsequently, methanol was added dropwise to the reaction solution to terminate the BBr3 reaction. The reaction solution was added dropwise to deionized water, the solid was separated by filtration, and the crude product was purified by washing with water and dichloromethane sequentially. Thin-layer chromatography (TLC) using dichloromethane as the eluent showed no impurities, indicating complete demethylation. The product was vacuum dried at 60 °C for 24 h to obtain black TBT-T-TPA-O powder. Yield: (83.4 mg, 88.1%).

[0039] 1 H NMR (500 MHz, DMSO- d 6) δ 9.43 (s, 4H), 7.53 (s, 8H), 6.94 (d, J =45.0 Hz, 12H), 6.78 (d, J = 9.0 Hz, 8H), 4.85 (d, J = 34.3 Hz, 2H), 2.34 (s,1H), 1.40 – 1.27 (m, 8H), 0.99 – 0.91 (m, 3H), 0.86 (t, J = 7.2 Hz, 3H).

[0040] To investigate the optical properties of the molecules, this invention utilizes UV-Vis-NIR to explore the absorption spectra of four molecules: TBT-TPA-OMe, TBT-TPA-O, TBT-T-TPA-OMe, and TBT-T-TPA-O. The results are shown in [Figure number missing]. Figure 3 a-3d.

[0041] Depend on Figure 3 a- Figure 3As shown in section d, in the THF solvent system, the absorption peaks of TBT-TPA-OMe and TBT-T-TPA-OMe are approximately at 650 nm and 750 nm, respectively. This is because the π-bridge structure effectively extends the conjugated length of the molecule in the donor-acceptor (DA) structure, resulting in higher electron abundance and enhanced intramolecular charge transfer (ICT), which in turn causes a red shift in the absorption spectrum, facilitating the absorption of a wider spectral range of energy by the molecular material in sunlight. After demethylation of the precursors, the absorption peak positions of TBT-TPA-O and TBT-T-TPA-O in solution remain essentially unchanged, but they exhibit a wider absorption range, a phenomenon more pronounced in solid films. The clear and long absorption tails observed in the solid films of TBT-TPA-O and TBT-T-TPA-O indicate that they possess typical free radical characteristics in the solid state. This long absorption tail characteristic in the absorption spectra of these two molecules is typical of phenoxy radical absorption, which is generated by the oxidative dehydrogenation of the solid phenolic hydroxyl group.

[0042] Furthermore, the photoluminescence (PL) of the corresponding radicals of TBT-TPA-O and TBT-T-TPA-O molecules was completely quenched after demethylation, and the PLQY of the radicals was much lower than that of their precursors, almost negligible (<0.1%), indicating that the photoexcited state is easily dissipated through nonradiative transitions. These results further demonstrate that in the aggregated thin film state, TBT-TPA-O and TBT-T-TPA-O are easily oxidized by O2 in air to convert into open-shell radicals, both of which exhibit strong nonradiative decay and fluorescence quenching. For radical molecular materials, the radiative channel for fluorescence emission is almost forbidden, while the thermal dissipation channel is allowed, which greatly contributes to enhancing their solid-state photothermal conversion capability.

[0043] To further investigate the photothermal properties of solid powders, this invention used an infrared thermal imager to observe the temperature changes of four molecular solid powders—TBT-TPA-OMe, TBT-TPA-O, TBT-T-TPA-OMe, and TBT-T-TPA-O—under 808 nm laser irradiation. The results are shown below. Figure 4 a-4f.

[0044] Depend on Figure 4As shown in a-4f, when the solid powder is exposed to laser light, its temperature rises rapidly within 10 seconds, reaching its maximum temperature at approximately 60 seconds, and then remains stable and essentially unchanged. After the laser is turned off, the temperature rapidly drops back to room temperature. All four molecules in the powder exhibit extremely high photothermal conversion rates. This invention used 3-5 mg of solid powder containing four different molecules to study the effect of different irradiation power densities (0.3 to 1.5 W cm⁻²) on photothermal conversion. The results show that higher irradiation power densities lead to higher heating rates and higher maximum equilibrium temperatures. The maximum equilibrium temperature shows a significant linear correlation with the irradiation power. Furthermore, 5 mg of solid powder containing four different molecules was placed at a power density of 1.1 W cm⁻². -2 Under an 808 nm laser, 10 heating and cooling cycles were performed. After 10 photothermal cycles, the temperature of all four molecules remained stable at the heating rate and reached their maximum temperature, with almost no change in the maximum temperature. This indicates that all four molecules possess good photothermal stability and strong resistance to photobleaching.

[0045] Comparing the photothermal properties of four different molecular powders, TBT-T-TPA-O exhibited the best photothermal performance. Under 808 nm laser irradiation, with a power density of 1.1 W / cm⁻², TBT-T-TPA-O reached a maximum temperature of 225℃. This is because its strong DA molecular structure enhances intramolecular interactions, thereby increasing absorption in the near-infrared region, broadening the absorption spectrum, and enhancing the molecule's light absorption capacity. The introduction of the thiophene group as a π-bridge structure generates strong intramolecular charge transfer (ICT) and a smaller band gap, leading to an increase in the molar extinction coefficient and a significant increase in the probability of nonradiative transitions. The free radicals introduced after demethylation further broaden the molecule's absorption range and lead to strong nonradiative decay and fluorescence quenching. This indicates that its radiative emission pathway is almost forbidden, and energy is more easily dissipated through nonradiative transitions.

[0046] To further investigate the solar thermal performance of four molecules—TBT-TPA-OMe, TBT-TPA-O, TBT-T-TPA-OMe, and TBT-T-TPA-O—this invention introduces solid powders of these four molecules into porous polyurethane (PU) foam with low thermal conductivity, constructing a two-dimensional interface solar-driven water evaporation system. Specifically, a cylindrical PU foam with a diameter of 4 cm and a thickness of 3 cm was placed on a petri dish. Then, 20 mg of the four different molecule powders were completely dissolved in 5 mL of a dichloromethane / tetrahydrofuran mixed solvent to prepare a solution. Next, this solution was added dropwise to the surface of the PU foam until the foam was completely absorbed. Finally, the loaded PU foam was dried in an oven at 80°C for 1 hour to remove the solvent. The results are shown below. Figure 5 .

[0047] Depend on Figure 5 As different molecular powders are added, the PU surface gradually becomes rougher, and fine powder particles can be observed, indicating that all four types of molecules are effectively loaded onto the PU foam surface in the form of micro-aggregates. The crisscrossing microporous structure inside the foam effectively promotes water transport and concentrates the heat generated by the molecular powders, thereby significantly accelerating water evaporation.

[0048] To further evaluate the photothermal conversion efficiency of four polyurethane (PU) foams with different molecular loadings, this invention used infrared (IR) thermal imaging technology to record the temperature changes of the PU foams in air. The results are shown below. Figure 6 a-6f.

[0049] Depend on Figure 6 As shown in a-6f, under simulated sunlight (1 kW m²), the four types of PU foam loaded with molecular powders reached temperature equilibrium in approximately 60 seconds. Under standard sunlight, the temperatures of TBT-TPA-OMe+PU, TBT-T-TPA-OMe+PU, TBT-TPA-O+PU, and TBT-T-TPA-O+PU reached 64°C, 70°C, 80°C, and 83°C, respectively.

[0050] PU foams with different molecular loadings were placed in simulated seawater at a fixed height, ensuring the foam surface remained slightly above the water surface and kept moist during the test. The entire foam was placed on an electronic balance, and the mass loss of desalinated seawater was recorded every 5 minutes. Evaporation curves were plotted to evaluate the efficiency of solar-driven interfacial water evaporation. Simultaneously, the temperature change of the evaporator was recorded using an infrared thermal imager. After one hour of irradiation, the temperatures of the water-wetted TBT-TPA-OMe+PU, TBT-T-TPA-OMe+PU, TBT-TPA-O+PU, and TBT-T-TPA-O+PU reached 41℃, 38℃, 47℃, and 50℃, respectively. After one hour of continuous illumination, the temperature rise of the PU foams loaded with different molecular powders remained essentially constant, demonstrating excellent photobleaching stability.

[0051] The moisture weight change versus time curves show that the moisture evaporation rate of the four molecularly loaded PU foams is positively correlated with the photothermal conversion efficiency of their respective molecular powders. TBT-T-TPA-O+PU exhibits the highest interfacial moisture evaporation efficiency, with an evaporation rate of 1.356 kg m⁻² h⁻¹. Theoretical calculations indicate that its solar-driven moisture evaporation efficiency reaches 93.05%, exceeding most reported organic small-molecule photothermal materials and comparable to the most advanced organic photothermal materials currently available. The wetting temperature of pure PU foam without molecules is 32°C, and its water evaporation rate is 0.2849 kg m⁻² h⁻¹, indicating that the contribution of PU foam to the photothermal conversion process is minimal.

[0052] Furthermore, this invention further investigated the repeatability and photobleaching resistance of four molecularly loaded PU foams during water evaporation. After five consecutive repeated experiments, the water evaporation performance remained almost unchanged, and the equilibrium temperature during the process was essentially the same as before the experiment. To verify the feasibility of seawater desalination, actual seawater samples were collected from the South China Sea, and seawater desalination experiments were conducted using TBT-T-TPA-O+ PU foam. The concentrations of the main ions Na⁺, Mg²⁺, Ca²⁺, and K⁺ before and after simulated seawater desalination were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the concentrations in distilled water were significantly lower than those in bulk water, and lower than the drinking water standards of the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA), indicating that seawater desalination has good potential.

[0053] Given the excellent photothermal conversion capabilities of molecular solid powders, this invention also investigates their potential contribution to thermoelectric conversion after photothermal conversion, aiming to utilize solar energy more effectively. This process involves converting the thermal energy generated by photothermal materials into electrical energy using the Seebeck effect, which is caused by the temperature difference between the hot and cold ends of a thermoelectric device. In a simulation experiment, 10 mg of each of four molecular solid powders were dissolved in 2 ml of a dichloromethane / tetrahydrofuran mixed solvent until completely dissolved, and then uniformly coated onto the hot end surface of the thermoelectric device. After the solvent evaporated, the molecular solids adhered tightly to the surface of the thermoelectric module. The cold end of the thermoelectric device was connected to a dual-tower heat sink, and thermally conductive silicone grease was applied to the contact surface to promote heat transfer and keep the cold end temperature as close to ambient temperature as possible. Under simulated solar radiation, the photothermal solid molecules on the device surface gradually heated up, while the temperature on the back of the module remained lower. This created a temperature difference between the hot end on the upper surface and the cold end on the back, causing charge carriers to accumulate on the back of the device, generating a potential difference and thus a current. When the temperature remained constant, the current tended to stabilize. The results are shown below. Figure 7 a-7f.

[0054] Depend on Figure 7As shown in a-7f, the thermoelectric devices coated with four different molecules all exhibited excellent thermoelectric performance under a single solar radiation intensity. When sunlight irradiates the surface of the thermoelectric device, the surface temperature of the photothermal molecules rises, and the temperature difference between the upper and lower ends generates voltage and current. The images show that the current and voltage gradually increase in a short period of time, reaching equilibrium output after 90 seconds and remaining essentially constant. The TBT-T-TPA-O molecule showed the best performance, achieving a stable open-circuit voltage of 245mV and a current of 41mA under simulated sunlight irradiation of 1 kW m⁻². Calculations show that its output power is 9.84 mW and its output power density is 3.936 W·m⁻². After five photothermal cycles, the temperature of all four solid-state powder thermoelectric devices maintained stable voltage and current output, with the maximum stable voltage and current remaining essentially unchanged, demonstrating excellent thermal stability. Subsequently, increasing the simulated solar radiation intensity from 1 kW m⁻² to 2 kW m⁻² significantly improved the thermoelectric performance of the four solid-state molecular thermoelectric devices. For example, the stable open-circuit output voltage of TBT-T-TPA-O increased to 450 mV, the current increased to 82 mA, and the output power increased to 38 mW. Subsequently, when the solar radiation intensity increased to 3 kW m⁻², a single thermoelectric device could drive a turbofan. To evaluate the performance of the thermoelectric device under actual outdoor conditions, the solar radiation intensity was measured using a densitometer under actual outdoor conditions in Shenzhen, China, with a result of 0.9 kW m⁻². Connecting eight thermoelectric devices in series also enabled the driving of a turbofan. These experimental results effectively demonstrate the feasibility of combining TBT-T-TPA-O solid powder molecules with thermoelectric modules for solar-thermal-electrical energy conversion, showcasing the material's enormous application potential in the thermoelectric field.

[0055] This invention designs a novel system that combines solar-driven water evaporation with solar thermal power generation to achieve efficient utilization of solar energy. Polyurethane (PU) foam loaded with TBT-T-TPA-O photothermal molecules is cut into appropriately sized areas with a thickness of approximately 3 mm and adhered to the surface of a thermoelectric device using thermally conductive silicone grease. The low-density PU foam allows the thermoelectric device to float on the water surface, with its surface slightly above the water level. When exposed to sunlight, the temperature of the PU material containing photothermal molecules rises, accelerating the evaporation of water from its surface. During this process, the lower end of the thermoelectric device is immersed in water and cooled by the water to maintain a temperature close to room temperature, thus generating electricity using the temperature difference between the upper and lower ends of the thermoelectric device. This achieves the dual functions of solar-driven water evaporation and thermoelectric power generation. Results are shown below. Figure 8 a-8d.

[0056] Depend on Figure 8As shown in a-8d, the experimental setup achieved a water evaporation rate of 1.36 kg m⁻² h⁻¹ under standard solar radiation intensity, with an efficiency of 93.4%. This performance remained essentially unchanged compared to the system without the thermoelectric device. Furthermore, under sunlight, the temperature difference between the PU surface and the water increased rapidly, causing the open-circuit voltage to reach a maximum value of 145 mV.

[0057] To utilize sunlight more effectively, this invention employs the focusing principle of a Fresnel lens to concentrate outdoor sunlight within a suitable range. This effectively increases the radiation intensity of outdoor sunlight without consuming any additional energy. Experimental results show that as the intensity of sunlight increases, the surface temperature of the PU foam loaded with photothermal molecules gradually rises, while the temperature of the water remains essentially constant at room temperature, leading to a gradual increase in the temperature difference between the upper and lower surfaces of the thermoelectric device. When the outdoor concentrated solar radiation intensity is 1.0, 2.0, 3.0, and 5.0 kW m⁻², the maximum stable open-circuit voltages are 145, 265, 370, and 400 mV, respectively.

[0058] These data demonstrate that this combined heat and power (CHP) system not only utilizes sunlight to heat water for evaporation but also converts some of the easily dissipated heat into electricity. This overcomes the limitations of traditional single-energy conversion methods, providing a feasible solution for outdoor seawater desalination and power generation. Furthermore, the system employs an efficient and convenient solar concentrating method, effectively and significantly improving the intensity of solar radiation under actual outdoor conditions, further realizing more efficient utilization of solar energy and contributing to the sustainable development of green energy.

[0059] The above embodiments are merely illustrative examples 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. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An organic photothermal material, which is a compound as shown in formula (I), or a stereoisomer and a geometric isomer of the compound shown in formula (I); （I）； in: T is O, S, or Se; L1 and L2 are each independently a direct bond or a 5-8 heteroaryl group, wherein the 5-8 heteroaryl group may optionally be bonded by 1, 2, or 3 atoms selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, C 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups and C 1-6 Substituents of haloalkoxy groups; R1 is C 3-15 Alkyl or C 3-8 cycloalkyl, the C 3-15 Alkyl and C 3-8 The cycloalkyl group may optionally be surrounded by one, two, or three atoms selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups and C 1-6 Substituents of haloalkoxy groups; R2, R3, R4, and R5 are respectively H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups and C 1-6 The alkoxy group is a haloalkoxy group, and at least two of R2, R3, R4, and R5 are OH; R6 and R7 are independently H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C, respectively. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups and C 1-6 Halogenated alkoxy groups.

2. The organic photothermal material according to claim 1, characterized in that, L1 and L2 are independent direct bonds, 、 、 、 、 ； The above substituents may optionally be replaced by 1, 2 or 3 substituents selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3 and -OCH2CF2CHF2.

3. The organic photothermal material according to claim 1, characterized in that, R1 is , , , , , Cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; The above substituents may optionally be replaced by 1, 2 or 3 substituents selected from H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3 and -OCH2CF2CHF2.

4. The organic photothermal material according to claim 1, characterized in that, R6 and R7 are independently H, D, F, Cl, Br, I, NH2, CN, OH, NO2, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, -CHF2, -CF3, -CHFCH2F, -CF2CHF2, -CH2CF3, -CH2CF2CHF2, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, -OCHF2, -OCF3, -OCHFCH2F, -OCF2CHF2, -OCH2CF3, and -OCH2CF2CHF2, respectively.

5. The organic photothermal material according to claim 1, characterized in that, Both L1 and L2 are direct bonds; or both L1 and L2 are... or .

6. The organic photothermal material according to any one of claims 1-5, wherein it is a compound having one of the following structures or a stereoisomer or geometric isomer of a compound having one of the following structures: , , , , , , , , or .

7. A method for preparing the organic photothermal material according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Compound 1 and Compound 2 undergo a coupling reaction in the presence of a base and a Pd catalyst to generate Compound 3; Step 2: Compound 3 undergoes a demethylation reaction with BBr3 to produce the compound shown in formula (I); Among them, R8, R9, R 10 R 11 The independent components are H, D, F, Cl, Br, I, OH, NH2, CN, NO2, and C, respectively. 1-6 Alkyl, C 1-6 Alkoxy, C 1-6 Halogenated alkyl groups and C 1-6 Haloalkoxy groups, and R8, R9, R 10 R 11 At least two of them are C 1-6 Alkoxy; The reaction route is as follows: 。 8. The preparation method according to claim 7, characterized in that, The alkali mentioned in step 1 is selected from one or more of potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium hydroxide, and sodium hydroxide; the Pd catalyst is selected from one or more of Pd(PPh3)4, Pd(PPh3)2Cl2, and Pd(dppf)Cl2.

9. The application of the organic photothermal material according to any one of claims 1-6 in solar energy conversion or solar energy storage.

10. The application of the organic photothermal material according to any one of claims 1-6 in the fields of seawater desalination or thermoelectricity.

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