A spirocyclic molecular material containing free radicals, its preparation method and applications

Abstract

The present invention discloses a spirocyclic molecular material containing free radicals, a preparation method thereof and applications. The structural formula of the spirocyclic molecular material containing free radicals is: wherein X is CH or N, Y is O or NH, and each independently selects one of the following structures: "---" represents the connection site; is a free radical, and selects one of the following structures: represents the connection site. The spirocyclic molecular material containing free radicals provided by the present invention can form π-π, π-free radical, and free radical-free radical synergistic effects with inorganic carbon materials, optimize the three major parameters of the thermoelectric performance of organic-inorganic composite thermoelectric materials, and thus greatly improve the thermoelectric performance of organic-inorganic composite thermoelectric materials.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric materials, and particularly to a spirocyclic molecular material containing free radicals, a preparation method thereof, and an application thereof. Background Art

[0002] Organic thermoelectric materials have attracted much attention due to their advantages such as rich resources, diverse structures, low thermal conductivity, large-area production, and suitability for flexible wearable electronic devices. Organic thermoelectric materials also have excellent performance in the room temperature region and have advantages in low-temperature micro-temperature power generation and refrigeration, etc. It is expected to complement traditional inorganic thermoelectric materials and become one of the important energy devices in the new generation of flexible electronic devices. However, compared with traditional inorganic materials, the low electrical conductivity of organic thermoelectric materials results in their thermoelectric conversion efficiency being far lower than that of inorganic materials, which has become the main bottleneck for their commercial application. Improving thermoelectric performance is the core goal pursued by organic thermoelectric materials in their development so far and in the long term in the future.

[0003] Combining the characteristics of low thermal conductivity of organic materials and high electrical conductivity of inorganic materials, preparing organic-inorganic composite thermoelectric materials is an important method to improve thermoelectric performance. For an organic / inorganic composite system, it is necessary to make the two components uniformly dispersed and in close contact to achieve a hybridization effect. Otherwise, the performance of the composite system may not exceed that of the individual components, and it is difficult to reflect the advantages of the composite system. The key to the organic-inorganic composite thermoelectric system lies in improving the interaction between the two components to optimize the performance. Research shows that the chemical structure (conjugated system, heteroatom, side chain, etc.) of organic molecules is crucial for the thermoelectric performance of the composite system. By synthesizing organic conjugated molecules with novel structures, it is expected to obtain high-performance thermoelectric materials. However, at present, the structure-property relationship of organic molecules is not clear, and there is a lack of guiding ideas and strategies for regulating the performance of composite thermoelectric materials by their chemical structure. The organic-inorganic composite thermoelectric materials as a whole are still in the initial stage, and the organic materials suitable for the organic-inorganic composite thermoelectric material system still need to be further improved in enhancing the thermoelectric performance of the composite thermoelectric materials.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a spirocyclic molecular material containing free radicals, a preparation method thereof, and an application thereof, aiming to solve the problem that the organic materials suitable for the organic-inorganic composite thermoelectric material system still need to be further improved in enhancing the thermoelectric performance of the composite thermoelectric materials.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, there is provided a spirocyclic molecular material containing free radicals, wherein its structural formula is:

[0008]

[0009] Wherein, X is CH or N, and Y is O or NH;

[0010] Each independently selected from one of the following structures:

[0011]

[0012] "---" represents a connection site; is a free radical, selected from one of the following structures:

[0013] represents a connection site.

[0014] In a second aspect of the present invention, there is provided a method for preparing a spiro molecular material containing a free radical as described above in the present invention, which includes the steps of:

[0015] React with R1 to obtain a first intermediate;

[0016] React the first intermediate with lead dioxide or m-chloroperoxybenzoic acid to obtain the spiro molecular material containing a free radical;

[0017] Wherein, A is F, Cl, Br or I;

[0018] R1 is selected from one of the following structures:

[0019]

[0020] R2 is -B(OH)2 or -B(OC3H6)2, R3 is -Si(CH3)3, -OCOCH3, -SO2(C6H4)CH3 or -CH3, and R4 is -B(OH)2, -B(OC3H6)2 or H;

[0021] Optionally, when Y is O, The preparation method includes the steps of:

[0022] React with to obtain

[0023] Optionally, when Y is NH, The preparation method includes the steps of:

[0024] React with to obtain

[0025] In a third aspect of the present invention, there is provided an application of the spiro molecular material containing free radicals as described above in the preparation of a composite thermoelectric thin film.

[0026] In a fourth aspect of the present invention, there is provided a composite thermoelectric thin film, which includes the spiro molecular material containing free radicals as described above in the present invention and an inorganic carbon material.

[0027] Optionally, the inorganic carbon material includes at least one of carbon nanotubes, graphene, and fullerenes.

[0028] In a fifth aspect of the present invention, there is provided a method for preparing the composite thermoelectric thin film as described above in the present invention, which includes the steps of:

[0029] Providing a dispersion liquid containing an inorganic carbon material and a substrate;

[0030] Adding the spiro molecular material containing free radicals into a solvent to obtain a first solution;

[0031] Mixing the dispersion liquid containing the inorganic carbon material and the first solution to obtain a mixed liquid;

[0032] Transferring the mixed liquid onto the substrate and drying to obtain the composite thermoelectric thin film.

[0033] Optionally, the solvent includes at least one of chlorobenzene, chloroform, dichlorobenzene, ethanol, water, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide; or, the solvent includes at least one of triethylamine, polyethyleneimine, diethanolamine, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0034] In a sixth aspect of the present invention, there is provided a thermoelectric device, which includes the composite thermoelectric thin film as described above in the present invention.

[0035] Beneficial effects: When the spirocyclic molecular material containing free radicals with the said structure is used to prepare an organic-inorganic composite thermoelectric material, the three-dimensional structure of the spiro-conjugated molecule with cross-conjugation can form a strong π-π interaction with the curved surface of the inorganic carbon material, thereby achieving an increase in the carrier mobility and conductivity; the introduction of the free radical structure in the spirocyclic molecular material can not only regulate the energy levels of the spirocyclic molecule, but also enhance the interaction force between the spirocyclic molecule and the inorganic carbon material, promoting charge transfer and transport, and further increasing the conductivity; there is an energy filtering effect at the interface of the formed composite thermoelectric material system, which can scatter low-energy carriers while allowing high-energy carriers to pass through, thereby increasing the Seebeck coefficient of the composite thermoelectric material; the phonon scattering through the interface can effectively reduce the thermal conductivity of the composite thermoelectric material. By forming π-π, π-free radical, and free radical-free radical synergistic effects between the spirocyclic molecular material containing free radicals provided by the present invention and the inorganic carbon material, the three major parameters of the thermoelectric performance of the organic-inorganic composite thermoelectric material are optimized, thereby greatly improving the thermoelectric performance of the organic-inorganic composite thermoelectric material. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the composite thermoelectric material system of the spirocyclic molecule containing free radicals and carbon nanotubes in the embodiment of the present invention.

[0037] Figure 2 It is the 1H NMR spectrum of SDF-POH in Example 1 of the present invention.

[0038] Figure 3 It is the 13C NMR spectrum of SDF-POH in Example 1 of the present invention.

[0039] Figure 4 It is the electron paramagnetic resonance spectrum of SDF-PO in Example 1 of the present invention.

[0040] Figure 5 It is the infrared spectrum of SDF-PO in Example 1 of the present invention.

[0041] Figure 6 It is the 1H NMR spectrum of SFX1-POH in Example 2 of the present invention.

[0042] Figure 7 It is the 13C NMR spectrum of SFX1-POH in Example 2 of the present invention.

[0043] Figure 8 It is the electron paramagnetic resonance spectrum of SFX1-PO in Example 2 of the present invention.

[0044] Figure 9 It is the infrared spectrum of SFX1-PO in Example 2 of the present invention.

[0045] Figure 101H NMR spectrum of SFX2-POH in Example 3 of the present invention.

[0046] Figure 11 13C NMR spectrum of SFX2-POH in Example 3 of the present invention.

[0047] Figure 12 EPR spectrum of SFX2-PO in Example 3 of the present invention.

[0048] Figure 13 IR spectrum of SFX2-PO in Example 3 of the present invention.

[0049] Figure 14 1H NMR spectrum of SFX2-NH in Example 4 of the present invention.

[0050] Figure 15 13C NMR spectrum of SFX2-NH in Example 4 of the present invention.

[0051] Figure 16 EPR spectrum of SFX2-NO1 in Example 4 of the present invention.

[0052] Figure 17 IR spectrum of SFX2-NO1 in Example 4 of the present invention.

[0053] Figure 18 Test results of conductivity, Seebeck coefficient and power factor of p-type SFX1-PO / SWCNT composite thermoelectric thin film in Example 5 of the present invention.

[0054] Figure 19 Test results of conductivity, Seebeck coefficient and power factor of n-type SFX1-PO / SWCNT composite thermoelectric thin film in Example 5 of the present invention.

[0055] Figure 20 Test results of conductivity, Seebeck coefficient and power factor of p-type SFX2-PO / SWCNT composite thermoelectric thin film in Example 6 of the present invention.

[0056] Figure 21 Test results of conductivity, Seebeck coefficient and power factor of n-type SFX2-PO / SWCNT composite thermoelectric thin film in Example 6 of the present invention.

[0057] Figure 22 Schematic diagram of the structure of p-n type SFX2-PO / SWCNT thermoelectric generator in Example 8 of the present invention.

[0058] Figure 23Test results of voltage and output power of the P-N type SFX2-PO / SWCNT thermoelectric generator in Example 8 of the present invention at different temperature differences. Detailed implementation mode

[0059] The present invention provides a spiro molecular material containing free radicals, its preparation method and application. To make the purpose, technical solution and effect of the present invention clearer and more definite, the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0060] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific implementation modes and are not intended to limit the present invention.

[0061] An embodiment of the present invention provides a spiro molecular material containing free radicals, wherein its structural formula is:

[0062]

[0063] Wherein, X is CH or N, and Y is O or NH;

[0064] Each independently selects one of the following structures:

[0065]

[0066] "---" represents the connection site; is a free radical and selects one of the following structures:

[0067]

[0068] represents the connection site.

[0069] When the spirocyclic molecular material containing free radicals with the above structure is used in the preparation of organic-inorganic composite thermoelectric materials, the three-dimensional structure of the spiro-conjugated molecule's cross-conjugation can form a strong π-π interaction with the curved surface of the inorganic carbon material, thereby achieving an increase in carrier mobility and conductivity; the introduction of the free radical structure in the spirocyclic molecular material can not only regulate the energy levels of the spirocyclic molecule but also enhance the interaction force (such as van der Waals force, π-π stacking, etc.) between the spirocyclic molecule and the inorganic carbon material, promoting charge transfer and transport, and further increasing the conductivity; there is an energy filtering effect at the interface of the formed composite thermoelectric material, which can scatter low-energy carriers while allowing high-energy carriers to pass through, thereby increasing the Seebeck coefficient of the composite thermoelectric material; the thermal conductivity of the composite thermoelectric material can be effectively reduced through phonon scattering at the interface. By forming π-π, π-free radical, and free radical-free radical synergistic effects between the spirocyclic molecular material containing free radicals provided by the present invention and the inorganic carbon material, the three major parameters of the thermoelectric performance of the organic-inorganic composite thermoelectric material are optimized, thereby greatly improving the thermoelectric performance of the organic-inorganic composite thermoelectric material.

[0070] The embodiment of the present invention also provides a preparation method of the spirocyclic molecular material containing free radicals as described above in the embodiment of the present invention, which includes the steps:

[0071] React with R1 to obtain a first intermediate product;

[0072] React the first intermediate product with lead dioxide or m-chloroperoxybenzoic acid to obtain the spirocyclic molecular material containing free radicals;

[0073] wherein, A is F, Cl, Br, or I; R1 is selected from one of the following structures:

[0074]

[0075] R2 is -B(OH)2 or -B(OC3H6)2, R3 is -Si(CH3)3, -OCOCH3, -SO2(C6H4)CH3, or -CH3, and R4 is -B(OH)2, -B(OC3H6)2, or H;

[0076] In one embodiment, when Y is O, the preparation method of

[0077] React with to obtain Specifically, in an inert atmosphere, Mix them, then add methanesulfonic acid and raise the temperature to 150 °C, stir for 24 hours, and add water to quench the reaction after the reaction is complete; extract the reaction system with dichloromethane, dry it with anhydrous magnesium sulfate, remove the solvent using a rotary evaporator, and obtain the product after purification by column chromatography Y is O.

[0078] Wherein, Each independently selects one of the following structures:

[0079]

[0080] When Y is NH, The preparation method of includes the steps of:

[0081] Mix with react to obtain Wherein, Each independently selects one of the following structures:

[0082]

[0083] Furthermore, The preparation method of includes the steps of:

[0084] Mix with react to obtain

[0085]

[0086] Specifically, in an inert atmosphere, mix add o-dichlorobenzene under dark conditions, raise the temperature to 180 °C and stir for 7 hours, then quickly inject polyphosphoric acid and continue stirring for 20 hours. After the reaction is completed, add sodium hydroxide solution to quench the reaction, and obtain the intermediate product after purification by column chromatography; dissolve the obtained intermediate product in acetonitrile in an air atmosphere, stir for 6 hours under light conditions, extract the reaction system with dichloromethane, dry it with anhydrous magnesium sulfate, remove the solvent using a rotary evaporator, and obtain the product after purification by column chromatography Y is NH.

[0087] The embodiment of the present invention also provides an application of the spirocyclic molecular material containing free radicals as described above in the preparation of a composite thermoelectric thin film. When the spirocyclic molecular material containing free radicals is used to prepare an organic-inorganic composite thermoelectric thin film, π-π, π-free radical, and free radical-free radical synergistic effects can be generated with inorganic materials, improving the thermoelectric performance of the composite thermoelectric thin film.

[0088] An embodiment of the present invention also provides a composite thermoelectric thin film, which includes the spirocyclic molecular material containing free radicals and the inorganic carbon material as described above in the embodiment of the present invention.

[0089] In one embodiment, the inorganic carbon material includes at least one of carbon nanotubes, graphene, fullerenes, but is not limited thereto.

[0090] When the inorganic carbon material is a carbon nanotube, exemplarily, the composite thermoelectric material system composed of the carbon nanotube and the spirocyclic molecular material containing free radicals is as Figure 1 shown. This system utilizes the π-π, π-free radical, and free radical-free radical synergistic effects between the spirocyclic molecule containing free radicals and the carbon nanotube. Specifically, the three-dimensional structure of the spiroconjugated molecule's cross-conjugation can form a strong π-π interaction with the curved surface of the carbon nanotube, thereby realizing the improvement of the carrier mobility and conductivity; the introduction of the free radical structure can not only regulate the energy level of the organic molecule, but also enhance the interaction force between the organic molecule and the carbon nanotube, promoting charge transfer and transport, and further improving the conductivity; there is an energy filtering effect at the interface between the organic and inorganic materials in the composite thermoelectric thin film, which can scatter low-energy carriers while allowing high-energy carriers to pass through, thereby increasing the Seebeck coefficient of the composite thermoelectric thin film; the carbon nanotube is combined with the spirocyclic molecule containing free radicals, and the thermal conductivity of the composite thermoelectric thin film system can be effectively reduced through phonon scattering at the interface.

[0091] An embodiment of the present invention also provides a preparation method of the composite thermoelectric thin film as described above in the embodiment of the present invention, which is characterized by including the steps:

[0092] Providing a dispersion liquid containing an inorganic carbon material and a substrate;

[0093] Adding the spirocyclic molecular material containing free radicals into a solvent to obtain a first solution;

[0094] Mixing the dispersion liquid containing the inorganic carbon material and the first solution to obtain a mixed liquid;

[0095] Transferring the mixed liquid onto the substrate, and after drying, obtaining the composite thermoelectric thin film.

[0096] In one embodiment, the solvent includes at least one of chlorobenzene, chloroform, dichlorobenzene, ethanol, water, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide; or, the solvent includes at least one of triethylamine, polyethyleneimine, diethanolamine, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide.

[0097] The composite thermoelectric thin film provided by the embodiments of the present invention is a P-type composite thermoelectric thin film or an N-type composite thermoelectric thin film. Taking carbon nanotubes as an example, carbon nanotubes are doped with oxygen in the air to form a P-type thermoelectric material. At this time, it is compounded with a spirocyclic molecular material containing free radicals to form a P-type composite thermoelectric thin film. Dispersing carbon nanotubes in some solvents such as triethylamine can eliminate the influence of oxygen on carbon nanotubes. At this time, it is an N-type thermoelectric material, which is compounded with a spirocyclic molecular material containing free radicals to form an N-type composite thermoelectric thin film.

[0098] The embodiments of the present invention also provide a thermoelectric device, which includes the composite thermoelectric thin film as described above in the embodiments of the present invention.

[0099] The following is a detailed description through specific examples.

[0100] Example 1 Synthesis of Spiro Conjugated Organic Small Molecule (SDF-PO) Containing Phenoxy Radical

[0101] (1) The synthesis route is as follows:

[0102]

[0103] (2) The synthesis method is as follows:

[0104] Under the protection of N2, 0.2 mmol of compound 1a-1 is mixed with 0.8 mmol and added with 10 mL of tetrahydrofuran and 1 mL of 2M aqueous potassium carbonate solution. The mixed solution is bubbled with inert gas to remove oxygen for 15 minutes, then 0.02 mmol of tetrakis(triphenylphosphine)palladium is added, and the reaction is refluxed and stirred at 100 °C for 24 h. The reaction is monitored by a thin layer chromatography (TLC) plate. After the reaction is complete, water is added to quench the reaction, and it is extracted with dichloromethane, dried over anhydrous magnesium sulfate, and then the solvent is removed by rotary evaporation. The obtained residue is purified by silica gel column chromatography using petroleum ether / dichloromethane (volume ratio 10:1) as the eluent to obtain 120 mg of a cyan solid intermediate SDF-POH with a yield of 82%.

[0105] Under the protection of N2, 0.03 mmol of the intermediate SDF-POH is dissolved in 4 mL of dichloromethane, and then 3 mmol of lead dioxide is added, and the mixture is stirred at room temperature for 4 hours. The reaction is detected by a TLC plate. After the reaction is complete, filter paper is placed on the funnel and an appropriate amount of diatomaceous earth is added for suction filtration, and then it is stored in a vacuum drying oven for 8 hours to remove the solvent to obtain 20 mg of a dark green product SDF-PO with the structural formula with a yield of 100%.

[0106] The NMR data of SDF-POH are as follows:

[0107] 11H NMR(500 MHz, CDCl3) δ 7.86 (dd, J = 11.9, 7.8 Hz, 4H), 7.53 (d, J = 6.6 Hz, 2H), 7.35 (t, J = 7.5 Hz, 2H), 7.16 (s, 4H), 7.11 (t, J = 7.5 Hz, 2H), 6.83 (d, J = 7.6 Hz, 2H), 6.80 (s, 2H), 5.16 (s, 2H), 1.40 (s, 36H).

[0108] 13 13C NMR(126 MHz, CDCl3) δ 153.37 (s), 149.57 (s), 148.89 (s), 141.99 (s), 141.79 (s), 140.02 (s), 136.02 (s), 132.65 (s), 127.77 (s), 127.59 (s), 126.89 (s), 124.35 (s), 123.99 (s), 122.60 (s), 119.94 (d, J = 7.6 Hz), 77.04 (s), 66.21 (s), 34.36 (s), 30.27 (s).

[0109] The 1H NMR spectrum of SDF-POH is as shown in Figure 2 and the 13C NMR spectrum is as shown in Figure 3 .

[0110] SDF-PO cannot be characterized by NMR. Its electron paramagnetic resonance spectrum and infrared spectrum are as shown in Figure 4 and 5 respectively.

[0111] Synthesis of Spiro-Conjugated Organic Small Molecule (SFX1-PO) Containing Phenoxy Radical in Example 2

[0112] (1) The synthesis route is as follows:

[0113]

[0114] (2) The synthesis method is as follows:

[0115] Under the protection of N2, 3.6 mmol of bromofluorene ketone and 9.0 mmol of phenol were mixed, 25 mL of methanesulfonic acid was added and the temperature was raised to 150 °C, and the mixture was stirred for 24 hours. After the reaction was complete, water was added to quench the reaction. The reaction system was extracted with dichloromethane, dried over anhydrous magnesium sulfate, the solvent was removed using a rotary evaporator, and the product 1b-1 was obtained after purification by column chromatography.

[0116] Under the protection of N2, 0.2 mmol of compound 1b-1 and 0.8 mmol of Mix, add 10 mL of tetrahydrofuran and 1 mL of 2 M aqueous potassium carbonate solution. Bubble the mixed solution with an inert gas to remove oxygen for 15 minutes, then add 0.02 mmol of tetrakis(triphenylphosphine)palladium. Stir and reflux the reaction at 100 °C for 24 h, and monitor the reaction by TLC plate. After the reaction is complete, add water to quench the reaction, extract with dichloromethane, dry over anhydrous magnesium sulfate, rotary evaporate to remove the solvent, and purify the obtained residue by silica gel column chromatography using petroleum ether / dichloromethane (volume ratio 10:1) as the eluent to obtain 126 mg of a cyan solid intermediate SFX1-POH with a yield of 85%.

[0117] Under the protection of N2, dissolve 0.03 mmol of intermediate SFX1-POH in 4 mL of dichloromethane, then add 3 mmol of lead dioxide, and stir at room temperature for 4 hours. Detect the reaction by TLC plate. After the reaction is complete, pad the funnel with filter paper and add an appropriate amount of diatomaceous earth for suction filtration. Store in a vacuum drying oven for 8 hours to remove the solvent to obtain 22 mg of a dark green product SFX1-PO with the structural formula with a yield of 100%.

[0118] The NMR data of SFX1-POH are as follows:

[0119] 1 H NMR (400 MHz, DMSO) δ 8.03 (d, J = 7.9 Hz, 2H), 7.62 (d, J = 8.0 Hz, 2H), 7.34 (d, J = 9.2 Hz, 2H), 7.31–7.26 (m, 2H), 7.18 (s, 2H), 7.15 (s, 4H), 7.08 (s, 1H), 6.90 (t, J = 7.5 Hz, 2H), 6.45 (d, J = 9.2 Hz, 2H), 5.75 (s, 1H), 1.36 (s, 36H).

[0120] 13 C NMR (126 MHz, CDCl3) δ 155.29 (s), 153.52 (s), 151.69 (s), 142.28 (s), 137.92 (s), 136.14 (s), 132.43 (s), 127.99 (d, J = 18.8 Hz), 126.87 (s), 125.50 (s), 124.13 (s), 123.93 (s), 123.36 (s), 120.00 (s), 116.67 (s), 54.65 (s), 34.41 (s), 30.29 (s), 0.03 (s).

[0121] The 1H NMR spectrum of SFX1-POH is as shown in Figure 6 Figure [specific figure number], and the 13C NMR spectrum is as shown in Figure 7 Figure [specific figure number].

[0122] SFX1-PO cannot be characterized by NMR. Its electron paramagnetic resonance spectrum and infrared spectrum are shown in Figure 8 and 9 shown respectively.

[0123] Example 3 Synthesis of Spiro-Conjugated Organic Small Molecule (SFX2-PO) Containing Phenoxy Radical

[0124] (1) The synthesis route is as follows:

[0125]

[0126] (2) The synthesis method is as follows:

[0127] Under the protection of N2, 3.6 mmol of bromofluorenone and 9.0 mmol of a-naphthol were mixed, 25 mL of methanesulfonic acid was added and the temperature was raised to 150 °C, and the mixture was stirred for 24 hours. After the reaction was complete, water was added to quench the reaction. The reaction system was extracted with dichloromethane, dried over anhydrous magnesium sulfate, the solvent was removed using a rotary evaporator, and the product 1b-2 was obtained after purification by column chromatography.

[0128] Under the protection of N2, 0.2 mmol of compound 1b-2 was mixed with 0.8 mmol of , 10 mL of tetrahydrofuran and 1 mL of 2 M aqueous potassium carbonate solution were added. The mixed solution was bubbled with an inert gas to remove oxygen for 15 minutes, then 0.02 mmol of tetrakis(triphenylphosphine)palladium was added, and the mixture was refluxed and stirred at 100 °C for 24 h. The reaction was monitored by TLC plate. After the reaction was complete, water was added to quench the reaction, extracted with dichloromethane, dried over anhydrous magnesium sulfate, and then the solvent was removed by rotary evaporation. The obtained residue was purified by silica gel column chromatography using petroleum ether / dichloromethane (volume ratio 10:1) as the eluent to obtain 145 mg of yellow solid intermediate SFX2-POH with a yield of 86%.

[0129] Under the protection of N2, 0.03 mmol of intermediate SFX2-POH was dissolved in 4 mL of dichloromethane, then 3 mmol of lead dioxide was added, and the mixture was stirred at room temperature for 4 hours. The reaction was detected by TLC plate. After the reaction was complete, the funnel was lined with filter paper and an appropriate amount of diatomaceous earth was added for suction filtration, and the solvent was removed in a vacuum drying oven for 8 hours to obtain 25 mg of dark green product SFX2-PO with the structural formula The yield is 100%.

[0130] The NMR data of SFX2-POH are as follows:

[0131] 11H NMR (400 MHz, DMSO) δ 8.82 (d, J = 8.4 Hz, 2H), 8.12 (d, J = 8.0 Hz, 2H), 7.89 (d, J = 8.1 Hz, 2H), 7.79 (t, J = 7.7 Hz, 2H), 7.65 (t, J = 8.9 Hz, 4H), 7.46 (d, J = 8.7 Hz, 2H), 7.20 (s, 2H), 7.08 (s, 4H), 7.00 (s, 2H), 6.47 (d, J = 8.7 Hz, 2H), 5.76 (s, 1H), 1.29 (s, 36H).

[0132] 13 13C NMR (126 MHz, CDCl3) δ 156.53 (s), 153.47 (s), 145.98 (s), 142.54 (s), 138.08 (s), 136.06 (s), 133.60 (s), 132.38 (s), 127.67 (s), 127.17 (s), 126.45 (s), 126.07 (s), 125.89 (s), 124.67 (d, J = 4.4 Hz), 123.94 (s), 123.13 (s), 121.71 (s), 119.99 (s), 118.57 (s), 77.04 (s), 54.66 (s), 34.35 (s), 30.28 (s).

[0133] The 1H NMR spectrum of SFX2-POH is as Figure 10 shown, and the 13C NMR spectrum is as Figure 11 shown.

[0134] SFX2-PO cannot be characterized by NMR. Its electron paramagnetic resonance spectrum and infrared spectrum are as Figure 12 and 13 shown, respectively.

[0135] Example 4 Synthesis of Spiro-Conjugated Organic Small Molecule with Nitroxide Radical (SFX2-NO1)

[0136] (1) The synthesis route is as follows:

[0137]

[0138] (2) The synthesis method is as follows:

[0139] The synthesis of 1b-2 is the same as that in Example 3.

[0140] Under the protection of N2, 0.2mmol of compound 1b-2 was mixed with 0.8mmol of 4-amino-2,2,6,6-tetramethylpiperidine, and 10mL of anhydrous toluene was added. The mixed solution was deoxygenated by bubbling under inert gas for 15 minutes, and then 0.006mmol of palladium acetate, 0.04mmol of tri-tert-butylphosphine tetrafluoroborate, and 0.6mmol of potassium tert-butoxide were added, and the reaction was stirred at 100°C for 24h, and the reaction was monitored by TLC plate. After the reaction was complete, water was added to quench the reaction, and the mixture was extracted with dichloromethane. After drying with anhydrous magnesium sulfate, the solvent was removed by rotary evaporation, and the residue was purified by silica gel column chromatography using dichloromethane / methanol (volume ratio 10:1) as the eluent to obtain 119mg of light yellow solid intermediate SFX2-NH with a yield of 80%.

[0141] 0.03 mmol of the intermediate product SFX2-NH was dissolved in 4 mL of tetrahydrofuran, and then 3 mmol of m-chloroperbenzoic acid was added and stirred at room temperature for 9 hours. The reaction was detected by TLC plate. After the reaction was complete, water was added to quench the reaction, and then extracted with dichloromethane. After drying with anhydrous magnesium sulfate, the solvent was removed by rotary evaporation. The residue was purified by silica gel column chromatography using dichloromethane / ethyl acetate (volume ratio 10:1) as an eluent to obtain 22 mg of an orange solid product SFX2-NO1 with the structural formula Yield 95%.

[0142] The NMR data of SFX2-NH are as follows:

[0143] 1 H NMR (400MHz, CDCl3) δ8.73(d,J=8.3Hz,2H),7.76(d,J=8.1Hz,2H),7.68(t,J=7.6Hz,2H),7.53(dd,J=12.9,7.7Hz,4H),7.29(d,J=8.7Hz,2 H), 6.59 (t, J = 7.2Hz, 4H), 6.35 (s, 2H), 3.58 (t, J = 11.6Hz, 2H), 1.85 (d, J = 15.2Hz, 5H), 1.26 (s, 2H), 1.10 (d, J = 13.5Hz, 27H), 0.83 (s, 5H).

[0144] 1313C NMR (126 MHz, CDCl3) δ 155.29 (s), 153.52 (s), 151.69 (s), 142.28 (s), 137.92 (s), 136.14 (s), 132.43 (s), 127.99 (d, J = 18.8 Hz), 126.87 (s), 125.50 (s), 124.13 (s), 123.93 (s), 123.36 (s), 120.00 (s), 116.67 (s), 54.65 (s), 34.41 (s), 30.29 (s), 0.03 (s).

[0145] The 1H NMR spectrum of SFX2-NH is as Figure 14 shown, and the 13C NMR spectrum is as Figure 15 shown.

[0146] SFX2-NO1 cannot be characterized by NMR. Its electron paramagnetic resonance spectrum and infrared spectrum are respectively as Figure 16 and 17 shown.

[0147] Example 5 Thermoelectric Properties of SFX1-PO and Single-Walled Carbon Nanotube Composite Thermoelectric Films

[0148] Preparation of P composite material solution: Place 8 mg of single-walled carbon nanotubes (SWCNT) and 8 mL of chlorobenzene in a 25 mL round-bottom flask and sonicate for 4 h, then stir magnetically for 24 h to obtain a uniform SWCNT dispersion;

[0149] Weigh 10 mg of SFX1-PO (prepared in Example 2) and dissolve it in 1 mL of chlorobenzene to prepare an SFX1-PO solution with a concentration of 10 mg / mL;

[0150] Mix the SWCNT dispersion and the SFX1-PO solution in a certain ratio to prepare a P composite material solution; the mass of SFX1-PO accounts for 20%, 40%, 60%, and 80% of the total mass of SFX1-PO and SWCNT, respectively.

[0151] Preparation of N composite material solution: Place 8 mg of single-walled carbon nanotubes (SWCNT) and 8 mL of triethylamine in a 25 mL round-bottom flask and sonicate for 4 h, then stir magnetically for 24 h to obtain a uniform SWCNT dispersion;

[0152] Weigh 10 mg of SFX1-PO (prepared in Example 2) and dissolve it in 1 mL of triethylamine to prepare an SFX1-PO solution with a concentration of 10 mg / mL;

[0153] Mix the SWCNT dispersion liquid and the SFX1-PO solution in a certain proportion to prepare the N composite material solution; the mass of SFX1-PO accounts for 20%, 40%, 60%, and 80% of the sum of the masses of SFX1-PO and SWCNT respectively;

[0154] Preparation of the composite thermoelectric thin film: Drop the above-mentioned P-type and N-type composite material solutions onto the glass slides by the drop coating method, and wait for the solvent to naturally dry to form the P-type SFX1-PO / SWCNT composite thermoelectric thin film and the N-type SFX1-PO / SWCNT composite thermoelectric thin film respectively.

[0155] Measure the conductivity, Seebeck coefficient, and power factor of the thin film, and the results are as Figure 18 and 19 shown:

[0156] As Figure 18 shown, for the P-type SFX1-PO / SWCNT composite thermoelectric thin film, when the SFX1-PO content is 0%, the conductivity is 1576.6 S·m -1 , the Seebeck coefficient is 40.6 μV·K -1 , and the power factor is 260.1 μW·m -1 K -2 ; the conductivity of the P-type SFX1-PO / SWCNT composite thermoelectric thin film reaches the maximum value of 1609.9 S·cm -1 when the SFX1-PO content is 20%; the Seebeck coefficient of the P-type SFX1-PO / SWCNT composite thermoelectric thin film generally increases steadily with the increase of the SFX1-PO content, and can reach 50.6 μV·K -1 when the content is 80%, achieving a 24.6% performance improvement; the power factor reaches the maximum value of 350.1 μW·m -1 ·K -2 when the SFX1-PO content is 20%, achieving a 34.6% performance improvement.

[0157] As Figure 19 shown, for the N-type SFX1-PO / SWCNT composite thermoelectric thin film, when the SFX1-PO content is 0%, the conductivity is 828.1 S·cm -1 , the Seebeck coefficient is -33.4 μV·K -1 , and the power factor is 92.6 μW·m -1 ·K -2 ; the conductivity of the N-type SFX1-PO / SWCNT composite thermoelectric thin film generally decreases gradually with the increase of the SFX1-PO content; the Seebeck coefficient of the N-type SFX1-PO / SWCNT composite thermoelectric thin film generally increases steadily with the increase of the SFX1-PO content, and can reach -41.7 μV·K when the content is 60%-1 , achieving a 24.9% performance improvement; the power factor reaches a maximum of 114.3 μW·m -1 ·K -2 , achieving a 23.4% performance improvement.

[0158] Thermoelectric Properties of SFX2-PO and Single-Walled Carbon Nanotube Composite Thermoelectric Films in Example 6

[0159] Preparation of P composite material solution: Place 8 mg of single-walled carbon nanotubes (SWCNT) and 8 mL of chlorobenzene in a 25 mL round-bottom flask, sonicate for 4 h, and then stir magnetically for 24 h to obtain a uniform SWCNT dispersion;

[0160] Weigh 10 mg of SFX2-PO (prepared in Example 3) and completely dissolve it in 1 mL of chlorobenzene to prepare an SFX2-PO solution with a concentration of 10 mg / mL;

[0161] Mix the SWCNT dispersion and the SFX2-PO solution in a certain proportion to prepare a P-type composite material solution, where the mass of SFX2-PO accounts for 20%, 40%, 60%, and 80% of the sum of the masses of SFX2-PO and SWCNT, respectively.

[0162] Preparation of N composite material solution: Place 8 mg of single-walled carbon nanotubes (SWCNT) and 8 mL of triethylamine in a 25 mL round-bottom flask, sonicate for 4 h, and then stir magnetically for 24 h to obtain a uniform SWCNT dispersion;

[0163] Weigh 10 mg of SFX2-PO (prepared in Example 3) and completely dissolve it in 1 mL of triethylamine to prepare an SFX2-PO solution with a concentration of 10 mg / mL;

[0164] Mix the SWCNT dispersion and the SFX2-PO solution in a certain proportion to prepare N-type composite material solutions respectively, where the mass of SFX2-PO accounts for 20%, 40%, 60%, and 80% of the sum of the masses of SFX2-PO and SWCNT, respectively;

[0165] Preparation of composite thermoelectric films: Drop the P-type and N-type composite material solutions onto glass slides by drop coating, and wait for the solvent to naturally evaporate to form P-type and N-type SFX2-PO / SWCNT composite thermoelectric films respectively.

[0166] The results of testing the conductivity, Seebeck coefficient, and power factor of the films are as Figure 20 and 21 shown:

[0167] As Figure 20As shown, for the P-type SFX2-PO / SWCNT composite thermoelectric thin film, when the SFX2-PO content is 0%, the conductivity is 1576.6 S·m -1 , the Seebeck coefficient is 40.6 μV·K -1 , and the power factor is 260.1 μW·m -1 ·K -2 ; The conductivity of the P-type SFX2-PO / SWCNT composite thermoelectric thin film reaches a maximum value of 1738.5 S·cm when the SFX2-PO content is 20% -1 , achieving a significant performance improvement of 10.3%; The Seebeck coefficient of the P-type SFX2-PO / SWCNT composite thermoelectric thin film generally increases steadily with the increase of the SFX2-PO content and can reach 49.6 μV·K when the SFX2-PO content is 80% -1 , achieving a performance improvement of 22.2%; The power factor reaches a maximum value of 358.1 μW·m -1 ·K -2 when the SFX2-PO content is 20%, achieving a performance improvement of 37.6%.

[0168] As Figure 21 shown, for the N-type SFX2-PO / SWCNT composite thermoelectric thin film, when the SFX2-PO content is 0%, the conductivity is 828.1 S·m -1 , the Seebeck coefficient is -33.4 μV·K -1 , and the power factor is 92.6 μW·m -1 ·K -2 ; The conductivity of the N-type SFX2-PO / SWCNT composite thermoelectric thin film reaches a maximum value of 921.8 S·cm when the SFX2-PO content is 20% -1 , achieving a significant performance improvement of 11.3%; The Seebeck coefficient of the N-type SFX2-PO / SWCNT composite thermoelectric thin film generally increases steadily with the increase of the SFX2-PO content and can reach -45.1 μV·K when the SFX2-PO content is 60% -1 , achieving a performance improvement of 35%; The power factor reaches a maximum value of 163.8 μW·m -1 ·K -2 when the SFX2-PO content is 20, achieving a performance improvement of 76.9%.

[0169] Thermoelectric properties of the SDF-PO and single-walled carbon nanotube composite thermoelectric thin film in Example 7

[0170] The difference from Example 6 is only that SFX2-PO is replaced with SDF-PO therein. After testing, when the content of SDF-PO is 20 wt%:

[0171] The Seebeck coefficient of the P-type SDF-PO / SWCNT film is 46.9 μV·K -1 , and the conductivity is 1480.0 S·m -1 、The power factor is 325.6 μW·m -1 ·K -2 ;

[0172] The Seebeck coefficient of the N-type SDF-PO / SWCNT film is -37.9 μV K -1 , and the conductivity is 778.2 S·m -1 、The power factor is 112 μW·m -1 ·K -2 .

[0173] Example 8 Performance of a thermoelectric device based on a composite thermoelectric film of SFX2-PO and single-walled carbon nanotubes

[0174] The P-type and N-type composite material solutions are the P-type and N-type composite material solutions in Example 6 where the mass of SFX2-PO accounts for 20% of the sum of the masses of SFX2-PO and SWCNT;

[0175] The polyimide substrate (with a thickness of about 125 μm) is ultrasonically washed successively with acetone, isopropanol, and ethanol. Then, the P-type and N-type composite material solutions are respectively and uniformly drop-coated on the polyimide substrate to form films until the chlorobenzene / triethylamine completely volatilizes, and P-type and N-type SFX2-PO / SWCNT films are obtained respectively;

[0176] Then, five strips of 10 mm×30 mm are cut out from the flexible P-type and N-type SFX2-PO / SWCNT films respectively. As Figure 22 shown, after the P-type and N-type SFX2-PO / SWCNT films are alternately connected in series through copper wires and silver paste, they are pasted on the polyimide film to assemble a flexible P / N-type SFX2-PO / SWCNT thermoelectric generator. The thermoelectric generator is installed on a 4200 device performance test bench, with one end heated by a constant-temperature heater as the hot end and the other end as the cold end, so that a temperature difference appears between the two ends of the thermoelectric generator. The P-N type SFX2-PO / SWCNT thermoelectric generator is connected to a current-voltage tester (Keithley 4200A), and the current I and voltage U in the circuit at different temperature differences (10.3 K, 21.2 K, 29.6 K, 39.5 K, 50.0 K, 60.0 K) are measured, and the output power P = UI of the thermoelectric generator is calculated. The results are as Figure 23 shown:

[0177] The open-circuit voltage and short-circuit current of the P-N type SFX2-PO / SWCNT thermoelectric generator (TEG) increase with the increase of the temperature gradient. The highest open-circuit voltage, short-circuit current and output power at ΔT = 60K are 28.2mV, 198.6μA and 1.4μW respectively. The TEG exhibits relatively stable mechanical and thermal stabilities. The thermoelectric power does not decrease significantly after more than 300 bending cycles, and stable electrical properties are shown after heat treatment at high temperature in air for 10 hours. At the same time, after the thermoelectric generator is exposed to air for one week, the change in the open-circuit voltage of the thermoelectric generator is small, and the output power of the thermoelectric generator remains at about 70%.

[0178] The thermoelectric material formed by the composite of the spirocyclic molecular material containing free radicals and carbon nanotubes provided by the present invention has more significant advantages in thermoelectric performance compared with the thermoelectric materials formed by the composite of currently reported organic small molecules or polymers and carbon nanotubes, as shown in Tables 1-3 below:

[0179] In the following tables, S is the Seebeck coefficient, σ is the conductivity, and PFmax is the maximum power factor.

[0180] Table 1 Thermoelectric performance of the P-type composite thermoelectric materials provided by the present invention and those available in recent years

[0181]

[0182] Table 2 Thermoelectric performance of the N-type composite thermoelectric materials of the present invention and those available in recent years

[0183]

[0184]

[0185] Table 3 Performance of the P-N type thermoelectric devices of the present invention and those available in recent years

[0186]

[0187] In summary, the present invention provides a spirocyclic molecular material containing free radicals, a preparation method thereof, and an application thereof. When the spirocyclic molecular material containing free radicals with the above structure is used to prepare an organic-inorganic composite thermoelectric material, the three-dimensional structure of the spiro-conjugated molecule with cross-conjugation can form a strong π-π interaction with the curved surface of the inorganic carbon material, thereby realizing the improvement of the carrier mobility and conductivity; the introduction of the free radical structure in the spirocyclic molecular material can not only regulate the energy level of the spirocyclic molecule, but also enhance the interaction force between the spirocyclic molecule and the inorganic carbon material, promote charge transfer and transport, and further improve the conductivity; there is an energy filtering effect at the interface of the formed composite thermoelectric material system, which can scatter low-energy carriers and allow high-energy carriers to pass through, thereby increasing the Seebeck coefficient of the composite thermoelectric material; the phonon scattering at the interface can effectively reduce the thermal conductivity of the composite thermoelectric material. By forming π-π, π-free radical, and free radical-free radical synergistic effects between the spirocyclic molecular material containing free radicals provided by the present invention and the inorganic carbon material, the three major parameters of the thermoelectric performance of the organic-inorganic composite thermoelectric material are optimized, thereby greatly improving the thermoelectric performance of the organic-inorganic composite thermoelectric material.

[0188] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, modifications or changes can be made according to the above description, and all such modifications and changes should fall within the protection scope of the appended claims of the present invention.

Claims

1. A spirocyclic molecular material containing free radicals, characterized in that, Its structural formula is: Among them, X is CH, Y is O, Each independently selected from one of the following structures: "---" indicates the connection site; is a free radical, and its structure is Indicates the connection site.

2. A method for preparing a spirocyclic molecular material containing free radicals as described in claim 1, characterized in that, It includes the steps: React with R1 to obtain a first intermediate product; After reacting the first intermediate with lead dioxide, the spirocyclic molecular material containing free radicals is obtained; Among them, A is F, Cl, Br or I; R1 is R2 is -B(OH)2 or -B(OC3H6)2, and R3 is -Si(CH3)3.

3. The preparation method according to claim 2, characterized in that, The preparation method includes the steps of: React with to obtain 4. Application of the spirocyclic molecular material containing free radicals according to claim 1 in the preparation of a composite thermoelectric material.

5. A composite thermoelectric thin film, characterized in that, It includes the spirocyclic molecular material containing free radicals according to claim 1 and an inorganic carbon material.

6. The composite thermoelectric thin film according to claim 5, characterized in that The inorganic carbon material includes at least one of carbon nanotubes, graphene, and fullerenes.

7. A method for preparing a composite thermoelectric thin film according to any one of claims 5-6, characterized in that, It includes the steps: Provide a dispersion liquid containing an inorganic carbon material and a substrate; Add the spirocyclic molecular material containing free radicals to a solvent to obtain a first solution; Mix the dispersion liquid containing the inorganic carbon material and the first solution to obtain a mixed solution; Transfer the mixed solution onto the substrate, and after drying, obtain the composite thermoelectric thin film.

8. The preparation method according to claim 7, characterized in that, The solvent includes at least one of chlorobenzene, chloroform, dichlorobenzene, ethanol, water, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

9. The preparation method according to claim 7, characterized in that, The solvent includes at least one of triethylamine, polyethyleneimine, diethanolamine, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

10. A thermoelectric device, characterized in that, It includes the composite thermoelectric thin film according to any one of claims 5-6.

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