A controllable bending two-dimensional organic crystal and its preparation method and application

Abstract

The present invention discloses a controllably bendable two-dimensional organic crystal, its preparation method, and application. The preparation method comprises the following steps: dissolving an organic small molecule in a good solvent to obtain an organic small molecule solution; adding methanol to the organic small molecule solution to obtain a mixed solution; and dropwise adding the mixed solution to a substrate at 25 to 45°C. After evaporation of the solvent, the controllably bendable two-dimensional organic crystal is obtained. By regulating conditions such as the solvent and temperature during the crystal self-assembly process, the present invention achieves the controllable preparation of an organic polygonal crystal with a bendable structure. The resulting controllably bendable two-dimensional organic crystal can be used in optical waveguides to achieve flexible optical signal transmission. The production process is simple, easy to implement, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of organic semiconductor materials, and in particular to a controllably bendable two-dimensional organic crystal and a preparation method and application thereof. Background Art

[0002] In the information age, semiconductor chips, as core components of electronic devices, have consistently driven significant technological advancements, with their performance improvements. With the continuous advancement of chip manufacturing processes, the shrinking size of transistors has challenged Moore's Law, and chip energy consumption has become increasingly prominent. Against this backdrop, the rise of organic micro- and nanophotonic devices offers a new avenue for addressing the energy consumption, speed, and cost challenges of electronic chips (Nature 2020, 586, 207-216). Polygonal organic crystals, due to their significant advantages such as structural design, ease of solutionization, and low-cost processing, have shown great potential for application in a wide range of fields, including organic solar cells, organic field-effect transistors, and organic light-emitting diodes. Importantly, as devices move toward flexibility and wearability, polygonal organic crystals exhibit significant potential due to their unique size and interface effects (Adv. Mater. 2019, 31, 1803831). However, the complex self-assembly process of organic semiconductor molecules makes it difficult to precisely control the morphology and optical properties of the resulting polygonal organic crystals. This lack of controllability further complicates the fabrication of micro- and nanophotonic devices, such as organic optical waveguides.

[0003] As a new type of optical waveguide material, flexible organic single crystals have broad application prospects in information transmission in organic optoelectronic microcircuits. At the same time, the unique optical properties of bent organic polygonal crystals can also be used for information transmission in organic optoelectronic microcircuits, which has important scientific significance and practical value for the performance improvement and application prospects of organic micro-nanophotonic devices, and provides strong technical support for the realization of higher efficiency and lower energy consumption photonic devices. In order to achieve the bending of organic crystals, the method commonly used in the prior art is to artificially use a probe to apply mechanical stress to the crystal to achieve the purpose of bending, but after the mechanical stress is released, the crystal usually returns to a flat shape from the bent shape (Chem.Soc.Rev.2023,52,3098-3169). Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a two-dimensional organic crystal with controllable bending and a preparation method and application thereof.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0006] A first aspect of the present invention provides a method for preparing a controllably bendable two-dimensional organic crystal, comprising the following steps:

[0007] (1) dissolving an organic small molecule in a good solvent to obtain an organic small molecule solution; the organic small molecule is selected from one of dibenzopyrene (DbPy), perylene (Pe), 2,6-diphenylanthracene (DPA) and pyrene (Py);

[0008] (2) adding a poor solvent to the organic small molecule solution obtained in step (1) to obtain a mixed solution; the poor solvent is methanol;

[0009] (3) The mixed solution obtained in step (2) is added dropwise onto the substrate at 25-45° C., and the controllable bending two-dimensional organic crystal is obtained after the solvent evaporates.

[0010] The present invention first controls the crystal thermodynamic growth process through solvents, thereby causing molecules to grow in an orderly arrangement along the surface, thereby obtaining an organic polygonal crystal. The temperature is further controlled to reduce the thickness of the organic polygonal crystal, thereby obtaining a two-dimensional organic crystal. Introducing multiple organic solvents during the crystal self-assembly process can change the microenvironment in which the crystal grows. As the solvents evaporate and the crystals grow, turbulence occurs in the microenvironment due to the different polarities and evaporation concentrations among the multiple solvents, as well as temperature changes, which in turn generates weak stress on the two-dimensional organic crystal. Under the influence of different stresses, the two-dimensional organic crystal will bend unilaterally or simultaneously on both sides, thus achieving the controllable preparation of organic polygonal crystals with a bent structure, and ultimately obtaining a two-dimensional organic crystal with controllable bending.

[0011] Furthermore, in step (1), the good solvent is selected from one of dichloromethane (DCM), acetonitrile, tetrahydrofuran and toluene, preferably dichloromethane.

[0012] Furthermore, in step (1), the concentration of the organic small molecule in the organic small molecule solution is 0.01 to 10 mmol / L, preferably 0.5 to 5 mmol / L.

[0013] Furthermore, in step (1), the organic small molecule is dissolved in a good solvent and subjected to ultrasonic treatment, and heated until the organic small molecule is completely dissolved to obtain an organic small molecule solution.

[0014] Furthermore, the temperature at which the organic small molecules are completely dissolved must not exceed the boiling point of the solvent.

[0015] Furthermore, the volume ratio of the good solvent in step (1) to the poor solvent in step (2) is 1:(0.25-8), preferably 1:(0.25-4), and more preferably 1:(0.25-1).

[0016] A too low volume ratio of good solvent to poor solvent can easily affect the bending degree and crystal quality of the crystal. A smaller amount of poor solvent will exert less stress on the crystal during the solvent volatilization process, making it difficult to form effective bending. A larger amount of poor solvent can easily affect the crystal nucleation rate during the crystal assembly process, causing explosive nucleation, and the resulting crystal size becomes smaller and the thickness becomes larger, making it less likely to bend.

[0017] The temperature has a significant impact on the crystal growth rate. Lower temperatures can easily cause slow crystal growth, resulting in the molecules growing vertically in three dimensions, which is not conducive to reducing the thickness of the crystal and causing bending. Higher temperatures can easily cause rapid crystal growth, prompting the molecules to quickly and disorderly stack in two dimensions, forming an amorphous molecular film, which is no longer an organic low-dimensional single crystal with a regular morphology.

[0018] Preferably, in step (3), the mixed solution is added dropwise onto the substrate at 35-40°C.

[0019] Furthermore, in step (3), the substrate is a quartz plate or a glass plate.

[0020] The second aspect of the present invention provides a controllably bendable two-dimensional organic crystal prepared by the preparation method described in the first aspect. The controllably bendable two-dimensional organic crystal can be flexibly bent and has a curved curvature.

[0021] A third aspect of the present invention provides an application of the controllably bendable two-dimensional organic crystal described in the second aspect in an optical waveguide.

[0022] Furthermore, the controllably bendable two-dimensional organic crystal can be used as a flexible light transmission material to realize flexible optical signal transmission under the conditions of continuous excitation light with a wavelength of 355 to 532 nm, promoting the development of flexible photon transmission in micro-nanophotonics applications.

[0023] Beneficial effects of the present invention:

[0024] The present invention realizes the controllable preparation of organic polygonal crystals with a bent structure by regulating conditions such as solvent and temperature during the crystal self-assembly process, thereby obtaining two-dimensional organic crystals with controllable bending. The production process is simple and easy to implement.

[0025] The controllably bendable two-dimensional organic crystals prepared by the present invention can be used as flexible light transmission materials in optical waveguides to achieve flexible light signal transmission, promote the development of flexible photon transmission in micro-nanophotonics applications, and have good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a fluorescence microscope image of the unilaterally bent DbPy crystal prepared in Example 1.

[0027] Figure 2 This is a scanning electron microscope image of the unilaterally bent DbPy crystal prepared in Example 1.

[0028] Figure 3 This is a fluorescence microscope image of the unilaterally bent DbPy crystal prepared in Example 2.

[0029] Figure 4 This is a scanning electron microscope image of the unilaterally bent DbPy crystal prepared in Example 2.

[0030] Figure 5 This is a fluorescence microscope image of the double-sided bent DbPy crystal prepared in Example 3.

[0031] Figure 6 This is a scanning electron microscope image of the double-sided bent DbPy crystal prepared in Example 3.

[0032] Figure 7 This is a fluorescence microscope image of the double-sided bent DbPy crystal prepared in Example 4.

[0033] Figure 8 This is a fluorescence microscope image of the double-sided bent DbPy crystal prepared in Example 5.

[0034] Figure 9 This is a fluorescence microscope image of the bilaterally bent DPA crystal prepared in Example 8.

[0035] Figure 10 This is a fluorescence microscope image of the DbPy crystal prepared in Comparative Example 1.

[0036] Figure 11 This is a bright field microscope image of the DbPy crystal prepared in Comparative Example 1.

[0037] Figure 12 This is the emission spectrum of the DbPy crystal prepared in Comparative Example 1.

[0038] Figure 13 This is a fluorescence microscope image of the DbPy crystal prepared in Comparative Example 2.

[0039] Figure 14 Fluorescence microscope image and micro-region fluorescence spectrum of the double-sided bent DbPy crystal prepared in Example 3. DETAILED DESCRIPTION

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0042] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are all commercially available unless otherwise specified.

[0043] Example 1

[0044] A method for preparing a unilaterally bent DbPy crystal comprises the following steps:

[0045] (1) Dissolve 0.02 mmol of DbPy in 10 mL of dichloromethane, ultrasonicate, and heat until DbPy is completely dissolved to obtain a DbPy solution.

[0046] (2) Add 20 mL of methanol to the DbPy solution and shake to mix evenly to obtain a mixed solution.

[0047] (3) The mixed solution was added dropwise onto a quartz plate at 35°C. As the solvent evaporated, the mixture reached supersaturation and crystal growth occurred, resulting in a unilaterally bent DbPy crystal.

[0048] The unilaterally bent DbPy crystal prepared in Example 1 was characterized using a fluorescence microscope. The characterization results are shown in FIG. Figure 1 As shown, the DbPy crystal is bent but still maintains edge orange fluorescence emission.

[0049] The unilaterally bent DbPy crystal prepared in Example 1 was characterized using a scanning electron microscope. The characterization results are shown in FIG. Figure 2 As shown, the results show that the surface of the prepared bent crystal is smooth, and the crystal still retains the bent surface at the bend without breaking, proving that the DbPy crystal has good flexibility.

[0050] Example 2

[0051] A method for preparing a unilaterally bent DbPy crystal is substantially the same as the method of Example 1, except that in step (1), 0.05 mmol of DbPy is dissolved in 10 mL of dichloromethane.

[0052] The unilaterally bent DbPy crystal prepared in Example 2 was characterized using a fluorescence microscope. The characterization results are shown in FIG. Figure 3 As shown, nearly half of the DbPy crystal faces are bent, yet the edge still emits orange fluorescence, indicating that the crystal can withstand significant bending stress without fracturing. Example 2 demonstrates that increasing the amount of DbPy facilitates continued crystal growth during assembly, resulting in DbPy crystals with larger bending faces during the bending process.

[0053] The unilaterally bent DbPy crystal prepared in Example 2 was characterized using a scanning electron microscope. The characterization results are shown in FIG. Figure 4 As shown, the results show that the surface of the prepared crystal is smooth and the DbPy with a large bending surface does not break, proving that the prepared DbPy flexible crystal has a large stress tolerance.

[0054] Example 3

[0055] A method for preparing a double-sided bent DbPy crystal comprises the following steps:

[0056] (1) Dissolve 0.01 mmol of DbPy in 20 mL of dichloromethane, treat with ultrasound, and heat until DbPy is completely dissolved to obtain a DbPy solution.

[0057] (2) Add 20 mL of methanol to the DbPy solution and shake to mix evenly to obtain a mixed solution.

[0058] (3) The mixed solution was added dropwise onto a quartz plate at 40°C. As the solvent evaporated, the mixture reached supersaturation and crystal growth occurred, resulting in a double-sided bent DbPy crystal.

[0059] The double-sided bent DbPy crystals prepared in Example 3 were characterized using a fluorescence microscope. Figure 5 As shown, the DbPy crystal bends twice, resulting in a double-sided bent structure. The crystal surface is flat and smooth, and it emits orange light under UV irradiation. Example 3 demonstrates that reducing the concentration of small organic molecules and increasing the growth temperature can help induce the molecules to stack in a two-dimensional in-plane pattern, thereby reducing the thickness of the resulting organic polygonal crystal. During the methanol volatilization process, the stress of the solvent causes the crystal to bend on both sides.

[0060] The double-sided bent DbPy crystal prepared in Example 3 was characterized using a scanning electron microscope. The characterization results are shown in FIG. Figure 6 As shown, the results show that the surface of the prepared crystal is smooth and the bending surface is not broken, which proves that the prepared DbPy flexible crystal has a large stress tolerance.

[0061] Example 4

[0062] A method for preparing a bilaterally bent DbPy crystal is substantially the same as the method of Example 3, except that in step (2), 5 mL of methanol is added to the DbPy solution.

[0063] The double-sided bent DbPy crystals prepared in Example 4 were characterized using a fluorescence microscope. Figure 7 As shown, the DbPy crystal only slightly bends on both sides, and the crystal emits a faint orange light. Example 4 demonstrates that reducing the amount of the poor solvent methanol during solvent evaporation can weaken the driving force of the organic solvent methanol on the crystal, resulting in only a weak bend on both sides of the very thin DbPy crystal.

[0064] Example 5

[0065] A method for preparing a bilaterally bent DbPy crystal is substantially the same as the method of Example 3, except that in step (2), 7 mL of methanol is added to the DbPy solution.

[0066] The double-sided bent DbPy crystals prepared in Example 5 were characterized using a fluorescence microscope. Figure 8 As shown, the two sides of the DbPy crystal are greatly bent, and the crystal emits a weak orange light.

[0067] Example 6

[0068] A method for preparing a double-sided bent DbPy crystal is substantially the same as the method of Example 3, except that in step (1), dichloromethane is replaced with tetrahydrofuran.

[0069] The quality of the double-sided bent DbPy crystal prepared in Example 6 is poor, and its geometric morphology tends to be polygonal rather than rhombic. At this time, the strain resistance (flexibility) of the DbPy crystal deteriorates. Under the application of larger bending stress, the crystal no longer tends to form a larger bending angle, but breaks at the strain interface.

[0070] Example 7

[0071] A method for preparing a double-sided bent DbPy crystal is substantially the same as the method of Example 3, except that in step (1), dichloromethane is replaced by toluene.

[0072] As the solvent evaporates, during the molecular crystal self-assembly process, the bending angle of the double-sided bent DbPy crystal prepared in Example 7 becomes smaller and cannot be effectively enlarged.

[0073] Example 8

[0074] A method for preparing a double-sided bent DPA crystal comprises the following steps:

[0075] (1) Dissolve 0.01 mmol of DPA in 20 mL of dichloromethane, perform ultrasonic treatment, and heat until DPA is completely dissolved to obtain a DPA solution.

[0076] (2) Add 20 mL of methanol to the DPA solution and shake to mix evenly to obtain a mixed solution.

[0077] (3) The mixed solution was added dropwise onto a quartz plate at 40°C. As the solvent evaporated, the mixture reached supersaturation and crystal growth occurred, resulting in a double-sided bent DPA crystal.

[0078] The double-sided bent DPA crystals prepared in Example 8 were characterized using a fluorescence microscope. The characterization results are shown in FIG. Figure 9 As shown, the DPA crystal is bent twice, resulting in a double-sided bent structure. The crystal surface is flat and smooth, and emits blue light under ultraviolet light. Example 8 demonstrates that the preparation method of the present invention can also obtain double-sided bent organic crystals by selecting DPA molecules.

[0079] Comparative Example 1

[0080] A method for preparing a DbPy crystal comprises the following steps:

[0081] (1) Dissolve 0.05 mmol of DbPy in 10 mL of dichloromethane to obtain a DbPy solution.

[0082] (2) Add 20 mL of ethanol to the DbPy solution and shake to mix evenly to obtain a mixed solution.

[0083] (3) The mixed solution was added dropwise onto a quartz plate at 35°C. As the solvent evaporated, the mixture reached supersaturation and crystal growth occurred, resulting in DbPy crystals.

[0084] The DbPy crystals prepared in Comparative Example 1 were characterized using a fluorescence microscope. Figure 10 As shown, the results show that the prepared DbPy crystal morphology is a regular rhombus, and orange light is emitted from the edge.

[0085] The DbPy crystals prepared in Comparative Example 1 were characterized using a bright field microscope. Figure 11 As shown, the results show that the surface of the prepared DbPy crystal is flat and smooth.

[0086] The DbPy crystal prepared in Comparative Example 1 was tested using emission spectroscopy, and the characterization results are as follows: Figure 12As shown, the results show that the fluorescence emission peak of DbPy crystal is at 580nm.

[0087] Comparative Example 2

[0088] A method for preparing DbPy crystals is basically the same as the preparation method of Example 3, except that in step (2), methanol is replaced by n-hexane.

[0089] The DbPy crystals prepared in Comparative Example 2 were characterized using a fluorescence microscope. Figure 13 As shown, the results show that the prepared DbPy crystal morphology is a regular rhombus, and orange light is emitted from the edge.

[0090] Test Case

[0091] The double-sided bent DbPy crystal prepared in Example 3 was excited using a micro-area fluorescence spectrometer (micro-area spectroscopy system) with spatial resolution. The excitation light source was an ultraviolet laser with a wavelength of 475 nm, which excited the middle position of the DbPy in the crystal.

[0092] The test results are as follows Figure 14 As shown, from Figure 14 As can be seen in a, the excitation position emits strong orange fluorescence, and then the photons are transmitted in the crystal, so that bright orange light is observed at the bend and edge. By detecting the output fluorescence at the bend, the fluorescence spectra of the input light and the output light are collected, as shown in Figure 14 As shown in Figure (b), the peak positions of the fluorescence spectra of both the input and output light remain unchanged at 580 nm, indicating that the bent end facet behaves as a flexible waveguide for light. Existing crystals are often prone to brittle cracking or inflexibility, making them incapable of meeting the development needs of future flexible, wearable photonic devices. The bendable two-dimensional organic crystals provided by this invention lay a solid material foundation for future flexible photonic device applications, demonstrating promising applications for optical waveguiding along curvature.

[0093] The above examples and comparative examples demonstrate that the present invention achieves the controllable preparation of organic polygonal crystals with a kinked structure by regulating conditions such as solvent and temperature during the crystal self-assembly process, resulting in controllably bendable two-dimensional organic crystals. These controllably bendable two-dimensional organic crystals can be used as flexible light transmission materials in optical waveguides, enabling flexible optical signal transmission and promoting the development of flexible photon transmission in micro- and nanophotonics applications, demonstrating promising application prospects.

[0094] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a controllably bendable two-dimensional organic crystal, characterized in that: The following steps are involved: (1) dissolving an organic small molecule in a good solvent to obtain an organic small molecule solution; the organic small molecule is selected from one of dibenzopyrene, perylene, 2,6-diphenylanthracene and pyrene; (2) adding a poor solvent to the organic small molecule solution obtained in step (1) to obtain a mixed solution; the poor solvent is methanol; (3) The mixed solution obtained in step (2) is added dropwise to the substrate at 25-45°C. Introducing a variety of organic solvents during the self-assembly process of the crystal can change the microenvironment of the crystal growth. As the solvent evaporates and the crystal grows, due to the different polarities and evaporation concentrations among the various solvents, as well as the change in temperature, turbulence will occur in the microenvironment, thereby generating weak stress on the two-dimensional organic crystal. Under the influence of different stresses, the two-dimensional organic crystal will bend on one side or on both sides at the same time. After the solvent evaporates, the controllable bending two-dimensional organic crystal is obtained.

2. The preparation method according to claim 1, characterized in that In step (1), the good solvent is selected from one of dichloromethane, acetonitrile, tetrahydrofuran and toluene.

3. The preparation method according to claim 1, wherein In step (1), the concentration of the organic small molecule in the organic small molecule solution is 0.01-10 mmol / L.

4. The preparation method according to claim 1, characterized in that In step (1), the organic small molecule is dissolved in a good solvent, subjected to ultrasonic treatment, and heated until the organic small molecule is completely dissolved to obtain an organic small molecule solution.

5. The preparation method according to claim 1, characterized in that The volume ratio of the good solvent in step (1) to the poor solvent in step (2) is 1:(0.25-8).

6. The preparation method according to claim 5, characterized in that The volume ratio of the good solvent in step (1) to the poor solvent in step (2) is 1:(0.25-4).

7. The preparation method according to claim 1, wherein In step (3), the mixed solution is added dropwise onto the substrate at 35-40°C.

8. A controllably bendable two-dimensional organic crystal obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the controllably bendable two-dimensional organic crystal according to claim 8 in an optical waveguide.

10. The use according to claim 9, characterized in that The controllably bendable two-dimensional organic crystal is used as a flexible light transmission material.

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