Phenylalanine derivative small molecule self-assembly with piezoelectric properties, preparation method and application thereof

Abstract

The application discloses a phenylalanine derivative small molecule self-assembly body with piezoelectric performance, a preparation method and application thereof, relates to the technical field of functional materials, and through introduction of a chiral solvent complementary to the configuration of the phenylalanine derivative small molecule and combination of reverse-solvent water synergistic regulation, the solution polarity is significantly changed, the small molecule solubility is reduced, the molecule is promoted to quickly and directionally nucleate and self-assemble, a highly ordered microstructure is formed, molecular-level chiral space control is realized, and the piezoelectric performance is improved. The piezoelectric material can be widely applied to the fields of flexible sensors, biomedical devices, energy collection devices and the like.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a phenylalanine derivative small molecule self-assembled assembly with piezoelectric properties, its preparation method and its application, and particularly to a phenylalanine derivative small molecule self-assembled assembly with piezoelectric properties enhanced by the synergistic effect of chiral complementary regulation and antisolvent effect, its preparation method and its application. Background Technology

[0002] Materials exhibiting the piezoelectric effect are collectively referred to as piezoelectric materials, which can be divided into direct piezoelectric effect (a potential difference is generated when pressure is applied to the piezoelectric material) and inverse piezoelectric effect (mechanical stress is generated when voltage is applied to the piezoelectric material). Since its discovery by the Curie brothers in 1880, the piezoelectric effect has been widely used in piezoelectric sensing, energy harvesting, and filtering transducers. Therefore, the rational design and efficient synthesis of novel piezoelectric materials are of great practical significance for promoting the application of their basic research and industrialization.

[0003] Piezoelectric materials can be broadly classified into inorganic piezoelectric materials (such as lead zirconate titanate piezoelectric ceramics), organic piezoelectric materials (such as polyvinylidene fluoride), and composite piezoelectric materials. While traditional inorganic piezoelectric materials exhibit excellent piezoelectric properties, they suffer from poor flexibility and low biocompatibility, thus limiting their application in flexible and bio-friendly scenarios such as wearable electronic devices and implantable devices. These shortcomings necessitate the development of novel, flexible, environmentally friendly piezoelectric materials with superior piezoelectric properties through the rational design of raw materials and manufacturing methods. Organic small-molecule piezoelectric materials, due to their simple and efficient synthesis methods, environmental friendliness, and tunable structure, represent a new class of piezoelectric materials suitable for applications such as electronic skin, soft robots, health monitoring, motion monitoring, and wearable devices. Among these, phenylalanine derivatives of chiral organic small molecules, with their chiral characteristics and modifiable structure, have become the preferred substrates for controlling piezoelectric properties.

[0004] Phenylalanine derivatives can have their piezoelectric properties adjusted by acid doping. Among them, Chinese invention patent CN115458676B discloses that the properties of D-2AD bisegment derivatives can be adjusted by inorganic acids (hydrochloric acid, hydrobromic acid) or chiral acids (such as (S)-chloropropionic acid, (R)-chloropropionic acid), with inorganic acids showing a more significant modulation effect. For single-segment derivatives (such as D-AD), hydrochloric acid has a relatively better modulation effect, but the effect of chiral acids is not satisfactory. This problem limits the expansion of the piezoelectric properties of single-segment derivatives. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a small molecule self-assembled phenylalanine derivative with piezoelectric properties, its preparation method, and its application.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] <First Aspect> A method for preparing small molecule self-assemblies of phenylalanine derivatives with piezoelectric properties includes the following steps: S1. Dissolve the chiral organic small molecule of phenylalanine derivative in an alcohol solvent to prepare a homogeneous solution; mix the chiral solvent with an antisolvent to prepare a chiral solution, wherein the stereoconfiguration of the chiral solvent and the chiral organic small molecule is non-racemic matched. S2. Mix the homogeneous solution with the chiral solution, and the chiral organic small molecules will self-assemble to obtain small molecule self-assembled bodies.

[0008] As one embodiment, the structural formula of the phenylalanine derivative is shown in Formula I or Formula II: .

[0009] As one embodiment, the chiral solvent is chiral chloropropionic acid or chiral camphorsulfonic acid.

[0010] As one embodiment, when the phenylalanine derivative is of formula I, the chiral solvent is R-chloropropionic acid or R-camphorsulfonic acid.

[0011] As one embodiment, when the phenylalanine derivative is of formula II, the chiral solvent is S-chloropropionic acid or S-camphorsulfonic acid.

[0012] As one embodiment, the alcohol solvent includes one or more of ethanol, hexafluoroisopropanol, isopropanol, trifluoroethanol, and n-butanol.

[0013] In some embodiments, the alcohol solvent is anhydrous ethanol.

[0014] As one implementation, the antisolvent is water.

[0015] As one embodiment, the concentration of the homogeneous solution is 4~10 mM.

[0016] In some embodiments, the concentration of the homogeneous solution is 10 mM.

[0017] As one embodiment, the concentration of the chiral solution is 4~10 mM.

[0018] In some embodiments, the concentration of the chiral solution is 10 mM.

[0019] As one embodiment, the molar ratio of the phenylalanine derivative to the chiral solvent is 1:1~2.

[0020] In some embodiments, the molar ratio of the phenylalanine derivative to the chiral solvent is 1:1.

[0021] <Second aspect> The piezoelectric phenylalanine derivative small molecule self-assemblies were prepared using the above method.

[0022] As one implementation, the effective piezoelectric coefficient of the self-assembled body is 10.5~21.1 pm V. -1 .

[0023] <Third aspect> Small molecule self-assemblies of phenylalanine derivatives with piezoelectric properties can be applied in the fields of flexible sensors, biomedical devices, energy harvesting devices, electronic skin, soft robots, health monitoring, motion monitoring or wearable devices.

[0024] <Fourth Aspect> A piezoelectric device includes two metal electrodes and a flexible piezoelectric thin film layer and a PDMS protective layer located between the two metal electrodes. The flexible piezoelectric thin film layer is a phenylalanine derivative small molecule self-assembled body prepared by the above method.

[0025] In one implementation, the metal electrode adjacent to the flexible piezoelectric thin film layer is the bottom electrode, and the other metal electrode is the top electrode.

[0026] In one embodiment, the PDMS protective layer covers the side of the flexible piezoelectric thin film layer away from the bottom electrode, and together with the flexible piezoelectric thin film layer, is sandwiched between two metal electrodes.

[0027] As one embodiment, the method for fabricating the piezoelectric device includes the following steps: (1) Using a metal sheet as the substrate and bottom electrode; (2) The organic small molecule assembly is deposited on the substrate surface by dip-coating method to form an assembly film; (3) Prepare a PDMS protective layer on the surface of the assembled film; (4) A top electrode is set on the PDMS protective layer and then encapsulated to obtain a flexible piezoelectric device.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The structural control of traditional piezoelectric materials usually relies on physical fields (such as electric fields and stress) or non-chiral solvents, making it difficult to achieve molecular-level chiral spatial control. This invention introduces chiral solvents that are complementary to the configuration of the target chiral molecule (such as R-type solvents controlling S-type molecules and S-type solvents controlling R-type molecules), and simultaneously introduces anti-solvents for synergistic control, thereby promoting molecular self-assembly and effectively improving piezoelectric properties.

[0029] (2) By introducing a chiral solvent, the present invention can induce a change in molecular conformation, achieve chiral spatial control at the molecular level, utilize its stereospecific interactions (such as hydrogen bonds, van der Waals forces, and steric hindrance effects) to achieve stereo matching, and use the matching strategy between molecules and solvent to form a directional induction effect on molecular conformation and dipole arrangement, forcing molecules to adopt a specific conformation, thereby enhancing the dipole moment and improving piezoelectric performance; at the same time, through the "soft template" effect of solvent chirality, programmable control of piezoelectric performance can be achieved, and the preparation process does not require complex external field treatment processes.

[0030] (3) The present invention introduces water as an antisolvent, which significantly changes the polarity of the solution, reduces the solubility of small organic molecules, and promotes the occurrence of molecular self-assembly; water can also provide a rapid supersaturation driving force and a sudden change in polar environment, enabling molecular assembly to form a highly ordered and oriented microstructure, further improving the piezoelectric performance; and during the lifting process, due to the antisolvent effect of water, as well as the rapid diffusion of ethanol and the concentration of the aqueous phase in the thin layer formed on the substrate surface, small organic molecules can cooperate with complementary chiral solvents to undergo rapid and directional nucleation and assembly, depositing on the substrate surface to form a uniform thin film.

[0031] (4) The phenylalanine derivative used in this invention is an organic small molecule piezoelectric material. Its synthesis method is simple, efficient, environmentally friendly, and its structure is controllable. The piezoelectric phenylalanine derivative small molecule self-assemblies prepared can be widely used in flexible sensors, biomedical devices and energy harvesting devices, and are also suitable for electronic skin, soft robots, health monitoring, motion monitoring, wearable devices and other fields. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a SEM image of the small molecule self-assembled polymer prepared by (S)-AD and (R)-chloropropionic acid in Example 1 on a copper substrate; Figure 2 The graph shows the linear relationship between the PFM amplitude of the small molecule self-assembled particles and the applied voltage in Example 1 and Comparative Example 3 without chiral solvents. Figure 3 The circuit-breaking voltage Voc of the assembled piezoelectric device based on (S)-AD and (R)-chloropropionic acid in Example 1 is... Figure 3 (a) and short-circuit current Isc signal diagram ( Figure 3 (b)); Figure 4 This is a SEM image of the small molecule self-assembled particles without the addition of antisolvent water in Comparative Example 1 on a copper substrate. Figure 5 The breaking voltage Voc of the piezoelectric device of the same chirality (S)-AD and (S)-chloropropionic acid assembly in Comparative Example 2 is... Figure 5 (a) and short-circuit current Isc signal diagram ( Figure 5 (b)); Figure 6 The breaking voltage Voc of the piezoelectric device assembled in Comparative Example 3 without the addition of chiral solvent and water is... Figure 6 (a) and short-circuit current Isc signal diagram ( Figure 6 (b)). Detailed Implementation

[0033] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0034] To facilitate understanding, the abbreviations mentioned below will be explained first: (S)-AD: is a small organic molecule based on a phenylalanine derivative. The reaction process is as follows: ; (R)-AD: is a small organic molecule based on a phenylalanine derivative. The reaction process is as follows: ; (R)-CPA: (R)-chloropropionic acid.

[0035] One or more embodiments of this application provide a method for preparing a small molecule self-assembled phenylalanine derivative with piezoelectric properties, comprising the following steps: Step S11: Dissolve the chiral organic small molecule in an alcohol solvent to prepare a homogeneous solution; mix the chiral solvent with an antisolvent to prepare a chiral solution, wherein the stereoconfiguration of the chiral solvent and the chiral organic small molecule is non-racemic matched. Step S12: Mix the homogeneous solution and the chiral solution, and the chiral organic small molecules will self-assemble to obtain small molecule self-assembled bodies.

[0036] As an example, chiral organic small molecules are single-segment phenylalanine derivative small molecules (R)-AD or (S)-AD.

[0037] In some embodiments, water is introduced as an antisolvent.

[0038] One or more embodiments of this application provide small molecule self-assemblies of phenylalanine derivatives with piezoelectric properties.

[0039] One or more embodiments of this application provide an application of a phenylalanine derivative small molecule self-assembled assembly in a piezoelectric device.

[0040] The fabrication method of piezoelectric devices includes the following steps: Using a metal sheet as the substrate and bottom electrode; The dip-coating method is used to deposit small organic molecule assemblies onto the substrate surface to form an assembly film. A PDMS protective layer was prepared on the surface of the assembled thin film. A flexible piezoelectric device is fabricated by placing a top electrode on a PDMS protective layer and then encapsulating it.

[0041] Example 1 This embodiment provides a method for preparing a small molecule self-assembly using (S)-AD and (R)-chloropropionic acid as an example, and a method for using the self-assembly to prepare a piezoelectric device, including the following steps: (1) Dissolve (S)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM); dissolve (R)-chloropropionic acid in water to prepare a chiral solution of 10 mM; (2) The homogeneous solution and the chiral solution were mixed in a molar ratio of (S)-AD to (R)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution. The final concentrations of the small molecule and chloropropionic acid were both 5 mM. (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 During the uniform lifting process, due to the anti-solvent effect of water and the rapid diffusion of ethanol in the solution thin layer formed on the substrate surface and the concentration of the aqueous phase, the organic small molecules (S)-AD and (R)-chloropropionic acid undergo rapid and directional nucleation and assembly, depositing on the substrate surface to form an assembled film. (5) Spin-coating PDMS prepolymer onto the surface of the assembled film, and curing it to form a PDMS protective layer; (6) Another copper sheet is attached to the PDMS protective layer as the top electrode and encapsulated with Kapton tape to obtain a flexible piezoelectric device with a sandwich structure.

[0042] In this embodiment, the morphology of the resulting assembly with piezoelectric properties is as follows: Figure 1 As shown.

[0043] The assembled film from step (4) was subjected to piezoelectric microscopy, and the linear relationship between the PFM amplitude and the applied voltage was as follows: Figure 2As shown, the slope represents the effective piezoelectric coefficient of the assembly. The figure shows that the effective piezoelectric coefficient of the (S)-AD assembly induced by the chiral solvent (R)-chloropropionic acid aqueous solution is increased to 21.0 pm V. -1 .

[0044] The device obtained by the organic small molecule assembly in step (6) was subjected to open-circuit voltage and short-circuit current tests. The open-circuit voltage V OC and short-circuit current I SC Signals such as Figure 3 As shown.

[0045] Example 2 This embodiment provides a method for preparing a small molecule self-assembly using (R)-AD and (S)-chloropropionic acid as an example, and a method for using the self-assembly to prepare a piezoelectric device, including the following steps: (1) Dissolve (R)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM); dissolve (S)-chloropropionic acid in water to prepare a chiral solution of 10 mM; (2) The homogeneous solution and the chiral solution were mixed in a molar ratio of (R)-AD to (S)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 During the uniform lifting process, the organic small molecule (R)-AD and (S)-chloropropionic acid undergo rapid and directional nucleation and assembly, depositing on the substrate surface to form an assembled thin film. (5) Spin-coating PDMS prepolymer onto the surface of the assembled film, and curing it to form a PDMS protective layer; (6) Another copper sheet is attached to the PDMS protective layer as the top electrode and encapsulated with Kapton tape to obtain a flexible piezoelectric device with a sandwich structure.

[0046] The piezoelectric coefficient of the assembled film from step (4) was measured by piezoelectric microscopy. The (R)-AD assembly, assembled by chiral solvent (S)-chloropropionic acid aqueous solution, was increased to 21.1 pm V. -1 Example 3 This embodiment provides a method for preparing a small molecule self-assembly using (S)-AD and (R)-camphorsulfonic acid as an example, and a method for using the self-assembly to prepare a piezoelectric device, including the following steps: (1) Dissolve (S)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM); dissolve (R)-camphorsulfonic acid in water to prepare a chiral solution of 10 mM. (2) The homogeneous solution and the chiral solution were mixed in a molar ratio of (S)-AD to (R)-camphorsulfonic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 During the uniform lifting process, the organic small molecules (S)-AD synergistically (R)-camphor sulfonic acid undergo rapid and directional nucleation and assembly, depositing on the substrate surface to form an assembled thin film. (5) Spin-coating PDMS prepolymer onto the surface of the assembled film, and curing it to form a PDMS protective layer; (6) Another copper sheet is attached to the PDMS protective layer as the top electrode and encapsulated with Kapton tape to obtain a flexible piezoelectric device with a sandwich structure.

[0047] The piezoelectric coefficient of the (S)-AD assembly induced by the chiral solvent (R)-camphor sulfonic acid aqueous solution was increased to 20.4 pm V by piezoelectric microscopy. -1 .

[0048] Comparative Example 1 This comparative example provides a method for preparing small molecule self-assemblies without adding antisolvents, including the following steps: (1) Dissolve (S)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM); use (R)-chloropropionic acid as a chiral solution; (2) The homogeneous solution and the chiral solution were mixed in a molar ratio of (S)-AD to (R)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 The organic small molecules (S)-AD synergistically assemble with (R)-chloropropionic acid during the lifting process and deposit on the substrate surface to form an assembled thin film.

[0049] In this embodiment, the morphology of the obtained assembly is as follows: Figure 4 As shown.

[0050] The piezoelectric coefficient of the assembled film from step (4) was measured by piezoelectric microscopy. The (S)-AD assembly, which was assembled using only the chiral solvent (R)-chloropropionic acid without antisolvent, had an effective piezoelectric coefficient of 12.8 pm V. -1 .

[0051] In this comparative example, the antisolvent effect of water was not utilized to induce assembly; the assembly process relied entirely on the slow, natural evaporation of ethanol. The results indicate that despite using the same chiral acid (R)-chloropropionic acid for doping, the lack of rapid supersaturation driving force and abrupt polarity changes provided by water resulted in a slow and poorly controllable molecular assembly process. This prevented the formation of a highly ordered, uniformly oriented microstructure, leading to its piezoelectric properties (12.8 pm V). -1 The performance was significantly lower than that obtained by induced assembly via a dual-solvent (ethanol-water) system in Example 1 (21.0 pm V). -1 ) Comparative Example 2 The preparation method of small molecule self-assemblies, using (S)-AD and (S)-chloropropionic acid with the same chirality as examples in this comparative example, includes the following steps: (1) Dissolve (S)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM); dissolve (S)-chloropropionic acid in water to prepare a chiral solution of 10 mM; (2) The homogeneous solution and the chiral solution were mixed in a molar ratio of (S)-AD to (S)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 During the uniform lifting process, the organic small molecules (S)-AD synergistically assemble with (S)-chloropropionic acid and deposit on the substrate surface to form an assembled thin film.

[0052] The piezoelectric coefficient of the assembled film from step (4) was measured by piezoelectric microscopy. The (S)-AD assembly induced by isochiral (S)-chloropropionic acid showed an effective piezoelectric coefficient of 17.1 pm V. -1 .

[0053] The piezoelectric device obtained in step (6) is subjected to open-circuit voltage and short-circuit current tests. The open-circuit voltage V OC and short-circuit current I SC Signals such as Figure 5 As shown.

[0054] Comparative Example 3 No chiral solvent was added in this comparative example. The specific preparation method is as follows: (1) Dissolve (S)-AD in anhydrous ethanol to prepare a homogeneous solution of 4.35 mg / mL (about 10 mM), add an equal volume of antisolvent water to induce small molecule assembly, and finally the small molecule concentration is 5 mM; (2) Using a copper sheet as the substrate and bottom electrode; (3) Using the dip-coating method, the substrate is immersed in the homogeneous solution obtained in step (1) and dipped at a speed of 50 μm / min. -1 The film is drawn at a uniform speed and deposited onto the substrate surface to form a small molecule film. (4) Spin-coating PDMS prepolymer onto the surface of a small molecule film, and then curing it to form a PDMS protective layer; (5) Another copper sheet is attached to the PDMS protective layer as the top electrode and encapsulated with Kapton tape to obtain a flexible piezoelectric device with a sandwich structure.

[0055] The assembled film from step (3) was subjected to piezoelectric microscopy, and the linear relationship between the PFM amplitude and the applied voltage was as follows: Figure 2 As shown, the slope represents the effective piezoelectric coefficient of the assembly. The figure shows that the effective piezoelectric coefficient of the (S)-AD assembly without added chiral solvent is 10.5 pm V. -1 .

[0056] The piezoelectric device prepared in step (5) was subjected to open-circuit voltage and short-circuit current tests. The open-circuit voltage V OC and short-circuit current I SC Signals such as Figure 6 As shown.

[0057] Comparative Example 4 In this comparative example, small molecule I and (R)-chloropropionic acid were used to prepare small molecule self-assemblies, including the following steps: The structural formula of small molecule I is as follows:

[0058] (1) Dissolve small molecule I in anhydrous ethanol to prepare a 10 mM homogeneous solution; dissolve (R)-chloropropionic acid in water to prepare a 10 mM chiral solution; (2) The homogeneous solution and the chiral solution are mixed in a molar ratio of small molecule I to (R)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1The small molecule I is pulled at a constant speed. During the pulling process, it assembles with (R)-chloropropionic acid and deposits on the substrate surface to form an assembled film.

[0059] The assembled film from step (4) was measured using piezoelectric microscopy, and the effective piezoelectric coefficient of the small molecule I assembly was 9.0 pm V. -1 .

[0060] Comparative Example 5 In this comparative example, small molecule I and (S)-chloropropionic acid were used to prepare small molecule self-assemblies, including the following steps: The structural formula of small molecule I is as follows:

[0061] (1) Dissolve small molecule I in anhydrous ethanol to prepare a 10 mM homogeneous solution; dissolve (S)-chloropropionic acid in water to prepare a 10 mM chiral solution; (2) The homogeneous solution and the chiral solution are mixed in a molar ratio of small molecule I to (S)-chloropropionic acid of 1:1 to obtain a small molecule self-assembled solution; (3) Using a copper sheet as the substrate and bottom electrode; (4) Using the dip-coating method, the substrate is immersed in the small molecule self-assembled solution obtained in step (2), and the dip-coating is performed at a speed of 50 μm min. -1 During the uniform lifting process, small molecule I synergistically assembles with (S)-chloropropionic acid and deposits on the substrate surface to form an assembled film.

[0062] The assembled film from step (4) was measured using piezoelectric microscopy, and the effective piezoelectric coefficient of the small molecule I assembly was 9.0 pm V. -1 .

[0063] Comparative Examples 4 and 5 show that the molecular structure of small molecule I is different from that of (R)-AD and (S)-AD. This molecule lacks conformational transitions induced by chiral solvents, and the introduction of chiral solvents cannot improve its piezoelectric coefficient.

[0064] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a small molecule self-assembled phenylalanine derivative with piezoelectric properties, characterized in that, Includes the following steps: S1. Dissolve the chiral organic small molecule of phenylalanine derivative in an alcohol solvent to prepare a homogeneous solution; mix the chiral solvent with an antisolvent to prepare a chiral solution, wherein the stereoconfiguration of the chiral solvent and the chiral organic small molecule is non-racemic matched. S2. Mix the homogeneous solution with the chiral solution, and the chiral organic small molecules will self-assemble to obtain small molecule self-assembled bodies; The structural formula of the phenylalanine derivative is shown in Formula I or Formula II: 。 2. The preparation method according to claim 1, characterized in that, The chiral solvent is chiral chloropropionic acid or chiral camphorsulfonic acid.

3. The preparation method according to claim 1, characterized in that, The antisolvent is water.

4. The preparation method according to claim 1, characterized in that, The alcohol solvents include one or more of ethanol, hexafluoroisopropanol, isopropanol, trifluoroethanol, and n-butanol.

5. The preparation method according to claim 1, characterized in that, The molar ratio of the phenylalanine derivative to the chiral solvent is 1:1~2.

6. The preparation method according to claim 1, characterized in that, The concentration of the homogeneous solution is 4~10 mM; the concentration of the chiral solution is 4~10 mM.

7. A small molecule self-assembled phenylalanine derivative with piezoelectric properties is prepared by the method according to any one of claims 1 to 5.

8. The application of the phenylalanine derivative small molecule self-assembly according to claim 7 in flexible sensors, biomedical devices, energy harvesting devices, electronic skin, soft robots, health monitoring, motion monitoring or wearable devices.

9. A piezoelectric device, characterized in that, It includes two metal electrodes, a flexible piezoelectric thin film layer and a PDMS protective layer. The flexible piezoelectric thin film layer is a small molecule self-assembled phenylalanine derivative as described in claim 7, and the flexible piezoelectric thin film layer is located between the two metal electrodes. The PDMS protective layer covers one side of the flexible piezoelectric thin film layer and is sandwiched between the two metal electrodes.

10. The method for preparing a piezoelectric device according to claim 9, characterized in that, Includes the following steps: (1) Using a metal sheet as the substrate and bottom electrode; (2) The organic small molecule assembly is deposited on the substrate surface by dip-coating method to form an assembly film; (3) Prepare a PDMS protective layer on the surface of the assembled film; (4) A top electrode is set on the PDMS protective layer and then encapsulated to obtain a flexible piezoelectric device.

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