Grain-boundary-free multilevel structure organic micro-nano crystal as well as preparation method and application of crystal-boundary-free multilevel structure organic micro-nano crystal

Abstract

The invention discloses a grain boundary-free multilevel structure organic micro-nano crystal and a preparation method and application thereof.The preparation method comprises the following steps that small organic molecules or coordination compounds are dissolved in an organic solvent, or acceptor molecules and donor molecules are dissolved in the organic solvent, and an organic micro-nano crystal stock solution is obtained; and regulating the viscosity of the organic micro-nano crystal stock solution to 0.5-4.0 mPa.s, dropwise adding at least one organic micro-nano crystal stock solution onto the substrate, and completely volatilizing the organic solvent to obtain the crystal boundary-free multilevel structure organic micro-nano crystal. According to the invention, a continuous photon transmission path is successfully constructed by using the crystal boundary-free characteristic of the crystal, so that the photon transmission efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic micro-nano materials, and particularly relates to an organic micro-nano crystal with a grain-boundary-free multi-level structure, a preparation method thereof, and an application thereof. Background Art

[0002] Organic functional nano-materials, with their rich structural diversity, high flexibility in processing and preparation, and good compatibility and integration characteristics, show great potential in constructing highly integrated and high-performance photonics devices, and are gradually becoming the core materials driving the development of the integrated photonics device field. Among this series of materials, organic low-dimensional crystals have received extensive attention and have been practically applied in recent years in the research and development of advanced optoelectronic devices and photonics components such as organic solid lasers, asymmetric optical waveguides, and photodetectors due to their unique chemical composition diversity, high structural regularity, extremely low defect density, and tunable optical properties.

[0003] In order to further improve the performance of optoelectronic devices and broaden their functions, researchers have designed and constructed a series of diverse low-dimensional crystal structures, and utilized the interaction and synergy between different components to composite multiple organic low-dimensional crystalline structures into complex and ordered multi-level structures. The construction of such multi-level structures can precisely regulate the optical properties of materials at the nano- to micron-scale, such as optimizing the absorption, scattering, and conduction processes of photons by changing the stacking order of layered structures, adjusting the lattice constant, or introducing defects. Therefore, the multi-level structure provides an effective way to achieve specific optoelectronic functions guided by structure.

[0004] Currently, the methods for constructing organic multi-level micro / nano structures are mainly divided into two categories: "top-down" and "bottom-up". The top-down methods mainly rely on direct techniques such as cutting, bonding, splicing, templating, or mechanical response methods, starting from larger materials and processing micro / nano structures with specific geometric configurations through physical means. The bottom-up methods, on the other hand, rely on natural assembly processes driven by non-covalent interactions (such as hydrogen bonds, van der Waals forces, π-π stacking, etc.), starting from molecules or nanoparticles and forming micro / nano crystalline materials with specific hierarchical structures through self-assembly.

[0005] However, the existing technologies still face many challenges in this field: (1) Crystal interface contamination and defect problems during mechanical operations: The multi-level structured crystals constructed by traditional micro-operation technologies such as shearing, pasting, or assembling often suffer from interface discontinuity problems. This discontinuity not only interrupts the smooth transmission path of photons but also easily introduces crystal contamination and interface defects during the operation, thus destroying the interface stability of the final material and having a negative impact on the overall performance of the device. (2) Interference of environmental factors during the self-assembly process: The solution self-assembly method is extremely vulnerable to environmental condition interference during actual operation. When self-assembling molecules move freely in the solution and attempt to form an ordered structure, if the environmental conditions are unstable or unsuitable, the intermolecular interaction forces may be disturbed, resulting in their inability to align precisely. In this case, even if there is a tendency of intermolecular attraction, they may form misalignments or defects because they cannot find the perfect binding positions. These misalignments and defects will gradually accumulate during the crystal growth process and finally form grain boundaries. (3) Structural stability problems: The structural stability of multi-level structured crystals is a key factor in maintaining high performance in practical applications. However, existing technologies are difficult to maintain the structural stability of low-dimensional multi-level structured crystals, which limits their wide application in high-performance and multi-functional optoelectronic devices. (4) Difficulty in precise size regulation: For each component in the multi-level structured crystals, existing technologies are difficult to achieve precise regulation of its size. This limits the potential of multi-level structured crystals in constructing photonic devices with specific functions. (5) Efficient photon transmission problems: Although multi-level structured crystals have the potential to achieve efficient photon transmission in theory, existing technologies are difficult to construct multi-level structured crystals that can achieve this goal. This is mainly due to the existence of defects such as grain boundaries, which severely weaken the photon transmission efficiency. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a grain-boundary-free multi-level structured organic micro-nano crystal, its preparation method and application, in order to construct a crystal with a continuous and non-destructive interface of an organic low-dimensional multi-level crystalline micro / nano structure, thereby greatly improving the photon transmission efficiency.

[0007] The present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention provides a preparation method of a grain-boundary-free multi-level structured organic micro-nano crystal, comprising the following steps:

[0009] (1) Dissolve an organic small molecule or a coordination compound in an organic solvent to obtain an organic micro-nano crystal stock solution; the organic small molecule is triphenylene (structural formula is ) or 2-(2-hydroxyphenyl) benzothiazole (structural formula is ), and the coordination compound is tris[2-phenylpyridine-C2,N]iridium(III) (structural formula is ) or tris[1-phenylisoquinoline-C2,N]iridium(III) (structural formula is ); or

[0010] Dissolve the receptor molecule and the donor molecule in an organic solvent to obtain an organic micro-nano crystal stock solution;

[0011] (2) Adjust the viscosity of the organic micro-nano crystal stock solution to 0.5 - 4.0 mPa·s, and drop at least one organic micro-nano crystal stock solution onto the substrate. After the organic solvent completely evaporates, the seamless multi-level structure organic micro-nano crystal is obtained.

[0012] In the present invention, by regulating key parameters such as the type of organic solvent, the concentration of the solution, and the cooling rate of the solution in the organic micro-nano crystal stock solution, the viscosity of the solution is effectively enhanced. On this basis, multiple crystals are induced to adhere to each other during the nucleation stage, and then undergo a process of cooperative co-growth. During this process, crystal defects can be eliminated, and finally, a seamless connection and grain boundary-free organic parallel-grown homo- or hetero-crystal structure is formed.

[0013] Further, in step (1), the receptor molecule is tetrafluoroterephthalonitrile (structural formula is ), benzene-1,2,4,5-tetracarbonitrile (structural formula is ), 2,4,6-trimethylbenzene-1,3,5-tricarbonitrile (structural formula is ), 7,7,8,8-tetracyano-p-benzoquinodimethane (structural formula is ) or tetrachloroisophthalonitrile (structural formula is ).

[0014] Further, in step (1), the donor molecule is acenaphthylene (structural formula is ), anthracene (structural formula is ), dithieno[2,3-d:2\',3\'-d\']benzo[1,2-b:4,5-b\']dithiophene (structural formula is ), benzo[c]phenanthrene (structural formula is ), pyrene (structural formula is ) or triphenylene.

[0015] Further, in step (1), the molar ratio of the receptor molecule to the donor molecule is (0.5 - 2):1, preferably 1:1.

[0016] Further, in step (1), the organic solvent is dichloromethane, tetrahydrofuran, methanol, ethanol, isopropanol, acetonitrile, cyclohexane, n-hexane or toluene.

[0017] Further, in step (1), the concentration of the organic small molecule or coordination compound in the organic micro-nano crystal stock solution is 2-30 mmol / L.

[0018] Further, in step (1), the concentration of the receptor molecule in the organic micro-nano crystal stock solution is 2-30 mmol / L.

[0019] Further, in step (1), the concentration of the donor molecule in the organic micro-nano crystal stock solution is 2-30 mmol / L.

[0020] Further, in step (2), the viscosity is controlled by adjusting the cooling rate of the organic micro-nano crystal stock solution, and the cooling rate is 4-8 °C / min.

[0021] Further, in step (2), one kind of organic micro-nano crystal stock solution is dropped onto the substrate, and a grain-boundary-free parallel epitaxial homo-crystal structure is formed after the organic solvent is completely volatilized; different organic micro-nano crystal stock solutions are dropped onto the substrate, and a grain-boundary-free parallel epitaxial hetero-crystal structure is formed after the organic solvent is completely volatilized.

[0022] The second aspect of the present invention provides a grain-boundary-free multi-level structure organic micro-nano crystal prepared by the preparation method described in the first aspect.

[0023] The third aspect of the present invention provides the application of the grain-boundary-free multi-level structure organic micro-nano crystal described in the second aspect in the optoelectronic field and the catalytic field, and it can be specifically applied to solar cells, transistors, electronic devices, optical instruments, etc.

[0024] The beneficial effects of the present invention:

[0025] 1. By using a high-viscosity solvent to induce the co-growth of multiple crystal nuclei, the present invention induces the epitaxial growth phenomenon at the initial stage of crystal nucleation, promotes the synergistic symbiosis of multiple crystals during the growth process, and simply and efficiently prepares crystals with an organic crystalline multi-level micro / nano structure without grain boundaries and undamaged interfaces by a solution method. The elimination of grain boundaries significantly improves the stability of the structure.

[0026] 2. The present invention effectively avoids the possible crystal interface contamination and defects caused by mechanical operations, combines low-ductility and high-crystallinity solid crystals with self-assembly technology, and can directly synthesize grain-boundary-free multi-level crystalline structures at the macroscopic scale (>1000 μm), mesoscopic scale (1-1000 μm), and microscopic scale (<1 μm).

[0027] 3. By precisely controlling the size of the co-growth region, the present invention realizes the precise control of the sizes of the various components of the multi-level structure crystal.

[0028] 4. The preparation method provided by the present invention has wide applicability and can be flexibly applied to various material systems such as organic small molecules, coordination compounds, and co-crystal molecular systems, and can successfully construct a crystal structure without grain boundaries with diverse emission wavelengths.

[0029] 5. By utilizing the grain boundary-free property of the crystal, the present invention successfully constructs a continuous photon transmission path, thereby significantly improving the photon transmission efficiency. Description of the Drawings

[0030] Figure 1 It is a characterization result diagram of the grain boundary-free multi-level structured organic micro-nano crystal prepared in Example 1; among them, a is the SEM diagram, b is the TEM diagram, c is the SAED diagram at position 1, d is the SAED diagram at position 2, and e is the SAED diagram at position 3.

[0031] Figure 2 It is a corresponding relationship diagram between the type of solvent and the solution concentration and the solution viscosity.

[0032] Figure 3 It is the FM diagram, viscosity data, and growth probability of the grain boundary-free multi-level structured organic micro-nano crystals prepared in Examples 1-5 and the organic micro-nano crystals prepared in Comparative Example 1; among them, a is Comparative Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, and f is Example 1.

[0033] Figure 4 It is the SEM diagram of the grain boundary-free multi-level structured organic micro-nano crystals prepared in Examples 1-5 and the organic micro-nano crystals prepared in Comparative Example 1 and the corresponding relationship diagram between the cooling rate and the degree of overlap; among them, a is the SEM diagram, from left to right are Comparative Example 1, Example 2, Example 3, Example 4, Example 5, and Example 1 in sequence, and b is the corresponding relationship diagram between the cooling rate and the degree of overlap.

[0034] Figure 5 It is the FM diagram and SEM diagram of the grain boundary-free multi-level heterostructured organic micro-nano crystals prepared in Example 7; among them, a is the FM diagram of benzene-1,2,4,5-tetracarbonitrile-benz[c]phenanthrene co-crystal, b is the FM diagram of tetrafluoroterephthalonitrile-triphenylene co-crystal, c is the FM diagram of the grain boundary-free multi-level heterostructured organic micro-nano crystals, and d is the SEM diagram of the grain boundary-free multi-level heterostructured organic micro-nano crystals.

[0035] Figure 6 It is the SEM diagram, FM diagram, and test result diagram of the photon transmission efficiency of the multi-level structured organic micro-nano crystals prepared in Comparative Example 2; among them, a1, a2 are the SEM diagrams, a3, a4 are the FM diagrams, and b is the test result diagram of the photon transmission efficiency.

[0036] Figure 7FM images and spatially resolved PL spectra of multi-level structured organic micro-nano crystals with different degrees of overlap; where, a1 is the FM image of multi-level structured organic micro-nano crystals with an overlap degree of 9.8%, a2 is the FM image after laser beam excitation corresponding to a1, a3 is the spatially resolved PL spectrum at the output port corresponding to a2, b1 is the FM image of multi-level structured organic micro-nano crystals with an overlap degree of 36.6%, b2 is the FM image after laser beam excitation corresponding to b1, b3 is the spatially resolved PL spectrum at the output port corresponding to b2, c1 is the FM image of multi-level structured organic micro-nano crystals with an overlap degree of 70.0%, c2 is the FM image after laser beam excitation corresponding to c1, and c3 is the spatially resolved PL spectrum at the output port corresponding to c2. Detailed implementation mode

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of this invention herein are only for the purpose of describing specific embodiments and are not intended to limit this invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the cited embodiments are not intended to limit the present invention.

[0039] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods, and the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0040] Example 1

[0041] A preparation method of a crystal boundary-free multi-level structured organic micro-nano crystal, comprising the following steps:

[0042] (1) Dissolve 0.05 millimoles (9.0 milligrams) of benzene-1,2,4,5-tetracarbonitrile and 0.05 millimoles (11.5 milligrams) of benzo[c]phenanthrene in 10 milliliters of isopropyl alcohol solvent to obtain an organic micro-nano crystal stock solution with a concentration of 5.0 millimoles per liter.

[0043] (2) Heat the above organic micro-nano crystal stock solution to 40°C, control the cooling rate of the stock solution at 8°C / min using a rotational rheometer, and drop it on a glass substrate after cooling to 5°C. After the solvent has completely evaporated, the formed parallel intergrown microstructure can be clearly observed on the glass substrate, and the crystal boundary-free multi-level structured organic micro-nano crystal is obtained.

[0044] Example 2

[0045] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level structure is basically the same as that of Example 1, except that: in step (2), the cooling rate is 4 °C / min.

[0046] Example 3

[0047] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level structure is basically the same as that of Example 1, except that: in step (2), the cooling rate is 5 °C / min.

[0048] Example 4

[0049] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level structure is basically the same as that of Example 1, except that: in step (2), the cooling rate is 6 °C / min.

[0050] Example 5

[0051] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level structure is basically the same as that of Example 1, except that: in step (2), the cooling rate is 7 °C / min.

[0052] Example 6

[0053] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level structure includes the following steps:

[0054] (1) Dissolve 0.05 mmol (11.4 mg) of triphenylene in 10 mL of isopropanol solvent to obtain an organic micro-nano crystal stock solution with a concentration of 5.0 mmol / L.

[0055] (2) Heat the above organic micro-nano crystal stock solution to 40 °C, control the cooling rate of the stock solution at 8 °C / min using a rotational rheometer, and after cooling to 5 °C, drop it on a glass substrate. After the solvent has completely evaporated, homoepitaxial growth of the crystals can be observed on the glass substrate to obtain a grain-boundary-free multi-level structure organic micro-nano crystal.

[0056] Example 7

[0057] A method for preparing an organic micro-nano crystal with a grain-boundary-free multi-level heterostructure includes the following steps:

[0058] (1) Dissolve 0.05 mmol (9.0 mg) of benzonitrile and 0.05 mmol (11.5 mg) of benzo[c]phenanthrene in 10 mL of isopropanol solvent to obtain an organic micro-nano crystal stock solution A with a concentration of 5.0 mmol / L; dissolve 0.05 mmol (10.0 mg) of tetrafluoroterephthalonitrile and 0.05 mmol (11.4 mg) of triphenylene in 10 mL of isopropanol solvent to obtain an organic micro-nano crystal stock solution B with a concentration of 5.0 mmol / L.

[0059] (2) Heat the above-mentioned organic micro-nano crystal stock solution A and organic micro-nano crystal stock solution B to 40 °C, and use a rotational rheometer to control the cooling rate of the stock solution at 8 °C / min. After cooling to 5 °C, simultaneously drop them onto a glass substrate. After the solvent has completely evaporated, heteroepitaxial growth of different crystals can be observed on the glass substrate, and finally a parallel epitaxial hetero-structured crystal, that is, a grain-boundary-free multi-level hetero-structured organic micro-nano crystal, is formed.

[0060] Comparative Example 1

[0061] A method for preparing an organic micro-nano crystal is basically the same as that of Example 1, except that: in step (2), the cooling rate is 3 °C / min.

[0062] Comparative Example 2

[0063] A method for preparing a multi-level structured organic micro-nano crystal includes the following steps:

[0064] (1) Dissolve 0.05 mmol (9.0 mg) of benzene-1,2,4,5-tetracarbonitrile and 0.05 mmol (11.5 mg) of benzo[c]phenanthrene in 10 mL of isopropanol solvent to obtain an organic micro-nano crystal stock solution A with a concentration of 5.0 mmol / L; drop the organic micro-nano crystal stock solution A onto a glass substrate at room temperature, and add a glass cover above the glass substrate to slow down the evaporation rate. After the solvent has completely evaporated, a benzene-1,2,4,5-tetracarbonitrile-benzo[c]phenanthrene co-crystal is obtained.

[0065] (2) Dissolve 0.05 mmol (10.0 mg) of tetrafluoroterephthalonitrile and 0.05 mmol (11.4 mg) of triphenylene in 10 mL of isopropanol solvent to obtain an organic micro-nano crystal stock solution B with a concentration of 5.0 mmol / L; drop the organic micro-nano crystal stock solution B onto a glass substrate at room temperature, and add a glass cover above the glass substrate to slow down the evaporation rate. After the solvent has completely evaporated, a tetrafluoroterephthalonitrile-triphenylene co-crystal is obtained.

[0066] (3) By means of probe technology, the above two co-crystals are mechanically spliced in a precise parallel docking manner to obtain a multi-level structured organic micro-nano crystal.

[0067] The grain-boundary-free multi-level structured organic micro-nano crystal prepared in Example 1 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The characterization results are as Figure 1As shown, by synthesizing these characterization results, it can be found that the external morphology of the crystal is composed of multiple crystal units. Among them, the central region shows a close symbiotic state without obvious interface separation. Whether in a single structural region or a symbiotic region, the crystal exhibits a very high crystallinity.

[0068] Based on Example 1, by changing the solvent type and solution concentration, the viscosity of the stock solution can be effectively regulated. The viscosity of the solution is accurately measured using a rotational rheometer, and the measurement results are as Figure 2 shown.

[0069] The fluorescence microscopy (FM) images of the grain-boundary-free multi-level structured organic micro-nano crystals prepared in Examples 1-5 and the organic micro-nano crystals prepared in Comparative Example 1 are as Figure 3 shown. As the solution viscosity increases, the probability of parallel twinning of the crystals also increases.

[0070] The SEM images of the grain-boundary-free multi-level structured organic micro-nano crystals prepared in Examples 1-5 and the organic micro-nano crystals prepared in Comparative Example 1, and the corresponding relationship diagram between the cooling rate and the overlapping degree are as Figure 4 shown. When the cooling rate is set to 0-3.5 °C / min (Comparative Example 1), after the solvent is completely evaporated, no twinning phenomenon of the crystals can be observed on the glass substrate; when the cooling rate is set to 4 °C / min (Example 2), the overlapping degree of the parallel twinning structure is about 8.8%; when the cooling rate is set to 5 °C / min (Example 3), the overlapping degree of the parallel twinning structure is about 20.6%; when the cooling rate is set to 6 °C / min (Example 4), the overlapping degree of the parallel twinning structure is about 33.3%; when the cooling rate is set to 7 °C / min (Example 5), the overlapping degree of the parallel twinning structure is about 52.5%; when the cooling rate is set to 8 °C / min (Example 1), the overlapping degree of the parallel twinning structure is about 75.1%. Figure 4 Samples Ⅰ, Ⅱ, Ⅲ, and Ⅳ in b of [Figure] represent multiple experiments conducted. By adjusting the cooling rate of the solution, the overlapping degree of the parallel twinning structure can be accurately controlled to be 8.8%-75.1%.

[0071] Figure 5 The FM image and SEM image of the grain-boundary-free multi-level heterostructured organic micro-nano crystals prepared in Example 7 are shown. From Figure 5 a of [Figure], the green-emitting eutectic 1 (benzene-1,2,4,5-tetracarbonitrile-benz[c]phenanthrene eutectic) can be seen. From Figure 5 b of [Figure], the blue-emitting eutectic 2 (tetrafluoroterephthalonitrile-triphenylene eutectic) can be seen. From Figure 5 c of [Figure], the two parallel-twinned eutectic structures can be seen. Figure 5In d, it shows that there is no obvious heterogeneous interface between the two eutectics, and a tight heterogeneous symbiotic part is formed in the middle region.

[0072] Figure 6 Figure showing the SEM images, FM images and test results of the photon transport efficiency for preparing multi-level structured organic micro-nano crystals in Comparative Example 2; among them, a1, a2 are SEM images, a3, a4 are FM images, and b is the test result image of the photon transport efficiency. From Figure 6 As can be seen from a1 - a3 in it, the multi-layer microstructure constructed in Comparative Example 1 has obvious splicing interfaces. Using a continuous laser with a wavelength of 380 nm and a laser spot diameter of 2 - 4 μm, it is focused on any layer of the mechanically spliced microstructure, such as Figure 6 shown in a4 in it, almost no optical signal is detected in adjacent layers, which is attributed to the discontinuous photon cross-layer transport caused by the splicing interface between the multi-layer microstructures, resulting in an inter-layer photon transport efficiency of only 2.1%, as Figure 6 shown in b in it, where OI, OⅡ, OⅢ, OⅣ represent the optical output ports, corresponding to Figure 6 a3 in it.

[0073] At a position 20 μm away from the output port OIII of the grain-boundary-free multi-level structured organic micro-nano crystals prepared by the present invention, a continuous laser with a wavelength of 380 nm (laser spot diameter of 2 - 4 μm) is used for excitation, and the FM image and the spatially resolved photoluminescence (PL) spectrum obtained at the output port are collected, as Figure 7 shown. Photons are guided by the seamless interface connecting the two crystals in the organic parallel growth microstructure and effectively propagate through the two crystals. Therefore, optical signals can be detected at all channel ports of the growth structure, and the inter-layer photon transport efficiency is significantly increased to 21.3%. The symbiotic part within the parallel growth microstructure establishes a seamless and efficient photon transport channel, effectively overcoming the limitation of the interface on photon transport, proving that the organic parallel growth structure designed based on the symbiotic mechanism of the present invention can solve the problem of low inter-layer photon transport efficiency caused by discontinuous crystal interfaces. In addition, at the same excitation position, the parallel growth microstructures with different overlap degrees exhibit different photon transport efficiencies. The gradual increase in the overlap degree leads to an increase in the PL intensity of the two exits located within the indirectly excited layer, thereby indicating an increase in the photon cross-layer transport efficiency. During the process of adjusting the overlap degree of the parallel growth microstructure from 9.8% to 70.0%, the inter-layer transport efficiency of photons increases from 21.3% to 54.9%. This is mainly due to the increase in the area ratio of the symbiotic segment, making the transport path of photons within the layered microstructure more concentrated and efficient, and ultimately improving the overall transport efficiency of photons.

[0074] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. Those skilled in the art should understand that other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A method for preparing organic micro-nano crystals with a multi-level structure without grain boundaries, characterized in that: The following steps are involved: (1) dissolving an organic small molecule or a coordination compound in an organic solvent to obtain an organic micro-nano crystal stock solution; the organic small molecule is triphenylene or 2-(2-hydroxyphenyl)benzothiazole, and the coordination compound is tris[2-phenylpyridine-C2,N]iridium(III) or tris[1-phenylisoquinoline-C2,N]iridium(III); or dissolving the acceptor molecule and the donor molecule in an organic solvent to obtain an organic micro-nano crystal stock solution; (2) adjusting the viscosity of the organic micro-nano crystal stock solution to 0.5-4.0 mPa·s, dripping at least one organic micro-nano crystal stock solution onto the substrate, and obtaining the organic micro-nano crystal with a multi-level structure without grain boundaries after the organic solvent is completely evaporated.

2. The preparation method according to claim 1, characterized in that: In step (1), the acceptor molecule is tetrafluoroterephthalonitrile, benzene-1,2,4,5-tetracarbonitrile, 2,4,6-trimethylbenzene-1,3,5-tricarboxylic acid nitrile, 7,7,8,8-tetracyanobenzoquinodimethane or tetrachloroisophthalonitrile.

3. The preparation method according to claim 1, characterized in that: In step (1), the donor molecule is acenaphthylene, anthracene, dithieno[2,3-d:2\',3\'-d\']benzo[1,2-b:4,5-b\']dithiophene, benzo[c]phenanthrene, pyrene or triphenylene.

4. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the acceptor molecule to the donor molecule is (0.5-2):

1.

5. The preparation method according to claim 1, characterized in that: In step (1), the organic solvent is dichloromethane, tetrahydrofuran, methanol, ethanol, isopropanol, acetonitrile, cyclohexane, n-hexane or toluene.

6. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the organic small molecules or coordination compounds in the organic micro-nano crystal stock solution is 2-30 mmol / L.

7. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the receptor molecules in the organic micro-nano crystal stock solution is 2-30 mmol / L.

8. The preparation method according to claim 1, characterized in that: In step (2), the viscosity is controlled by adjusting the cooling rate of the organic micro-nano crystal stock solution, and the cooling rate is 4-8°C / min.

9. An organic micro-nano crystal with a multi-level structure without grain boundaries prepared by the method according to any one of claims 1 to 8.

10. Application of the organic micro-nano crystals with a multi-level structure without grain boundaries as claimed in claim 9 in the fields of optoelectronics and catalysis.

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