A multi-component quantum dot heterostructure, and a method of making and use thereof

Abstract

The application provides a multi-component quantum dot heterostructure and a preparation method and application thereof. The preparation method comprises the following steps: dispersing at least two components of colloidal quantum dots in an alkane solvent to obtain a precursor solution; placing the precursor solution on the surface of a silicon-based micro-column template, then covering a base on the top of the silicon-based micro-column template, applying pressure, so that the precursor solution forms a capillary liquid bridge between the top of the silicon-based micro-column template and the base; and performing one-way evaporation treatment on the capillary liquid bridge structure to form a multi-component quantum dot heterostructure with size-oriented phase separation; the particle size of colloidal quantum dots of any component is different from the particle size of colloidal quantum dots of other components. The application provides a one-step method for preparing a multi-component quantum dot heterostructure, realizes the size-oriented phase separation and ordered assembly of the multi-component quantum dots, and has the advantages of simple process, large-scale microprocessing, good photoelectric performance and integration, and good application prospect in optoelectronic devices.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano fabrication and optoelectronic materials technology, and relates to a multi-component quantum dot heterostructure, its preparation method and application. Background Technology

[0002] The modern semiconductor and optoelectronic industries have an increasingly urgent need for monolithic integration of multiple materials. Devices such as photonic integrated circuits, multicolor microdisplays, and broadband photodetectors all require precise control over the spatial distribution of different functional materials. Colloidal quantum dots (CQDs) have become an ideal building block for the fabrication of multi-component micro / nano structures due to their advantages such as tunable photoelectric properties, high luminescence quantum yield, and solution processability.

[0003] The fabrication of traditional multi-component quantum dot heterostructures relies on complex multi-step microfabrication techniques such as photolithography, transfer printing, and wafer bonding, which suffer from problems such as cumbersome processes, high costs, poor material compatibility, and numerous interface defects. Self-assembly, as a bottom-up fabrication strategy, provides a simplified approach for the fabrication of multi-component structures. However, the chaotic and disordered capillary and Marangoni flows in solution-phase micro / nano fabrication can easily lead to phase separation and structural disorder in quantum dots, making it difficult to achieve precise spatial phase separation and ordered assembly.

[0004] Existing quantum dot phase separation technologies are mostly based on thermodynamic equilibrium or macroscopic scale systems. In micro-nano confined spaces, due to turbulent fluid dynamics and uncontrollable concentration gradients, it is impossible to achieve directional and controllable phase separation of quantum dots of different particle sizes, which restricts the efficient preparation of multi-component quantum dot heterostructures and their integrated application in optoelectronic devices.

[0005] Therefore, developing a simple and precisely tunable one-step fabrication method for multi-component quantum dot heterostructures is of great significance for promoting the miniaturization and integration of optoelectronic devices. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a multi-component quantum dot heterostructure, its preparation method, and its applications. This invention provides a one-step method for preparing multi-component quantum dot heterostructures based on capillary liquid bridge confinement processing. This method achieves directional phase separation and ordered assembly of multi-component quantum dots, is simple in process, can be microfabricated on a large scale, and the resulting structure exhibits excellent optoelectronic properties and integration, showing promising application prospects in optoelectronic devices.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a multi-component quantum dot heterostructure, the method comprising the following steps:

[0009] At least two types of colloidal quantum dots are dispersed in an alkane solvent to obtain a precursor solution;

[0010] The precursor solution is placed on the surface of a silicon-based micropillar template, and then a substrate is covered on the top of the silicon-based micropillar template. Pressure is applied so that the precursor solution forms a capillary bridge between the top of the silicon-based micropillar template and the substrate.

[0011] The capillary liquid bridge structure is subjected to unidirectional evaporation to form a multi-component quantum dot heterostructure with size-oriented phase separation.

[0012] The particle size of colloidal quantum dots of any component is different from that of colloidal quantum dots of other components.

[0013] As a preferred technical solution, in the colloidal quantum dots of the at least two components, the particle size ratio between the particle size of each quantum dot and the particle size of the other quantum dot is ≥1.1, preferably ≥1.9.

[0014] As a preferred technical solution, the alkane solvent has 6-10 carbon atoms.

[0015] As a preferred technical solution, the concentration of the precursor solution is 10 mg / mL to 100 mg / mL, preferably 10 mg / mL to 25 mg / mL.

[0016] As a preferred technical solution, the precursor solution is placed on the surface of the silicon-based micropillar template by drop addition.

[0017] As a preferred technical solution, the height of the silicon-based micropillar template is 5 μm to 15 μm.

[0018] As a preferred technical solution, the applied pressure is 1 MPa to 10 MPa.

[0019] As a preferred technical solution, the unidirectional evaporation treatment method includes:

[0020] Only the evaporation direction of one capillary bridge is retained, while the evaporation directions of the other capillary bridges are sealed.

[0021] In a second aspect, the present invention provides a multi-component quantum dot heterostructure, wherein the multi-component quantum dot heterostructure is prepared by the preparation method described in the first aspect;

[0022] The multi-component quantum dot heterostructure has a size-oriented phase separation structure, which is distributed longitudinally from front to back with increasing particle size, and the multi-component quantum dot heterostructure is arranged in a long-range ordered close-packed pattern.

[0023] As a preferred technical solution, the micro-line width in the long-range ordered close-packed structure of the multi-component quantum dot heterostructure is 2 μm to 10 μm.

[0024] Thirdly, the present invention provides an application of a multi-component quantum dot heterostructure, the application of which includes using the multi-component quantum dot heterostructure described in the second aspect in optoelectronic devices.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a one-step method for preparing multi-component quantum dot heterostructures based on capillary bridge confinement processing. The method involves mixing colloidal quantum dots of different components and particle sizes to form a capillary bridge. During unidirectional evaporation, the orientation of the temperature gradient, Marangoni vortex flow, and separation direction is maintained, causing the solvent to evaporate directionally along the front end of the capillary bridge. The evaporative cooling effect creates a temperature gradient along the length of the capillary bridge, driving a stable Marangoni vortex flow. Small-diameter colloidal quantum dots are enriched at the evaporation front end, and their concentration gradient drives larger-diameter quantum dots to diffuse and migrate towards the evaporation back end, achieving size-oriented phase separation. After complete solvent evaporation, quantum dots of different particle sizes self-assemble in one step to form multi-component quantum dot heterostructures. This invention utilizes a component-based quantum dot heterostructure to form a size-oriented phase-separated heterojunction structure of colloidal quantum dots with different particle sizes. This heterojunction structure has a smooth surface, regular and uniform size, high internal particle assembly order, and excellent optoelectronic properties. This invention abandons the complex multi-step processes of traditional photolithography and transfer, completing microfabrication through a one-step self-assembly, simplifying the processing flow, making operation convenient, and reducing preparation costs. Furthermore, by controlling the geometry of the silicon-based micropillar template, heterojunction structures with various morphologies such as microlines, microrings, polygons, letter arrays, and number arrays can be prepared. It is compatible with various colloidal materials and can achieve phase separation assembly of two-component, three-component, and even full-color quantum dots to meet the needs of different optoelectronic devices. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation method provided in Embodiment 1 of the present invention.

[0028] Figure 2 Fluorescence microscopy (left) and SEM image (right) of the two-component quantum dot heterostructure prepared by the preparation method provided in Example 1 of this invention.

[0029] Figure 3 Fluorescence microscopy (top) and SEM image (bottom) of the two-component quantum dot heterostructure prepared by the preparation method provided in Example 2 of this invention.

[0030] Figure 4Fluorescence microscope image of the two-component quantum dot heterostructure prepared by the preparation method provided in Example 3 of the present invention.

[0031] Figure 5 Fluorescence microscope image of the two-component quantum dot structure prepared by the preparation method provided in Example 4 of the present invention.

[0032] Figure 6 Fluorescence microscope image of the two-component quantum dot structure prepared by the preparation method provided in Example 5 of the present invention.

[0033] Figure 7 Fluorescence micrograph of the two-component quantum dot heterostructure prepared by the preparation method provided in Example 6 of the present invention.

[0034] Figure 8 Fluorescence microscope image of the two-component quantum dot structure prepared by the preparation method provided in Comparative Example 1 of this invention.

[0035] Figure 9 Fluorescence microscope image of the two-component quantum dot structure prepared by the preparation method provided in Comparative Example 2 of this invention.

[0036] Figure 10 The image shows a fluorescence microscope image of a two-component quantum dot structure prepared by the preparation method provided in Comparative Example 3 of this invention.

[0037] Figure 11 Fluorescence microscopy image of a dual-wavelength laser photonic integrated circuit composed of a multi-component quantum dot heterostructure provided in Application Example 1 of the present invention.

[0038] Figure 12 The diagram shows the lasing waveguide and wavelength division multiplexing results of the dual-wavelength laser photonic integrated circuit provided in Application Example 1 of the present invention.

[0039] Figure 13 A physical image (left) and a fluorescence microscope image (right) of the display device provided for application example 2 of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0042] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0044] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0045] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0047] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0048] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0049] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0050] In this invention, "room temperature" generally refers to 4℃~35℃, and may refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0051] In one embodiment, the present invention provides a method for preparing a multi-component quantum dot heterostructure, the method comprising the following steps:

[0052] At least two types of colloidal quantum dots are dispersed in an alkane solvent to obtain a precursor solution;

[0053] The precursor solution is placed on the surface of a silicon-based micropillar template, and then a substrate is covered on the top of the silicon-based micropillar template. Pressure is applied so that the precursor solution forms a capillary bridge between the top of the silicon-based micropillar template and the substrate.

[0054] The capillary liquid bridge structure is subjected to unidirectional evaporation to form a multi-component quantum dot heterostructure with size-oriented phase separation.

[0055] The particle size of colloidal quantum dots of any component is different from that of colloidal quantum dots of other components.

[0056] It should be noted that the colloidal quantum dots of the present invention can have at least two components or more than two components. Those skilled in the art can make adaptive selections and adjustments according to actual needs.

[0057] This invention provides a one-step method for preparing multi-component quantum dot heterostructures based on capillary bridge confinement processing. The method involves mixing colloidal quantum dots of different components and particle sizes to form a capillary bridge. During unidirectional evaporation, the orientation of the temperature gradient, Marangoni vortex flow, and separation direction is maintained, causing the solvent to evaporate directionally along the front end of the capillary bridge. The evaporative cooling effect creates a temperature gradient along the length of the capillary bridge, driving a stable Marangoni vortex flow. Small-diameter colloidal quantum dots are enriched at the evaporation front end, and their concentration gradient drives larger-diameter quantum dots to diffuse and migrate towards the evaporation back end, achieving size-oriented phase separation. After complete solvent evaporation, quantum dots of different particle sizes self-assemble in one step to form multi-component quantum dot heterostructures. This invention utilizes a component-based quantum dot heterostructure to form a size-oriented phase-separated heterojunction structure of colloidal quantum dots with different particle sizes. This heterojunction structure has a smooth surface, regular and uniform size, high internal particle assembly order, and excellent optoelectronic properties. This invention abandons the complex multi-step processes of traditional photolithography and transfer, completing microfabrication through a one-step self-assembly, simplifying the processing flow, making operation convenient, and reducing preparation costs. Furthermore, by controlling the geometry of the silicon-based micropillar template, heterojunction structures with various morphologies such as microlines, microrings, polygons, letter arrays, and number arrays can be prepared. It is compatible with various colloidal materials and can achieve phase separation assembly of two-component, three-component, and even full-color quantum dots to meet the needs of different optoelectronic devices.

[0058] In the preparation of the multi-component quantum dot heterostructure of the present invention, the selection of alkane solvents and the unidirectional evaporation process are both crucial and indispensable. Adjusting the solvent type, such as using aromatic hydrocarbon solvents, will prevent phase separation from occurring; while performing multidirectional evaporation during the evaporation process will result in inconsistent phase separation directions.

[0059] In some embodiments, in the colloidal quantum dots of the at least two components, the particle size ratio between the particle size of each quantum dot and the particle size of the other quantum dot is ≥1.1, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.05, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3, preferably ≥1.9.

[0060] It is understood that if the colloidal quantum dots in this invention have two components, the particle size will be first > second; and if there are more than two components, the particle size will be first > second > third, and so on; and the corresponding particle size ratios will be first / second, second / third in sequence.

[0061] This invention achieves size-oriented phase separation by controlling the particle size ratio between colloidal quantum dots of different components, especially by limiting the particle size ratio between each quantum dot and another quantum dot to ≥1.1. A further preferred ratio is ≥1.9, which more thoroughly achieves a heterostructure with ordered size-oriented phase separation. The degree of separation is positively correlated with the particle size ratio because the capillary force between particles at the assembly front increases as the particle size decreases: hydrostatic pressure drives particles away from the precipitation front, while capillary force keeps particles at the assembly front. Under constant hydrostatic pressure, an increase in particle size weakens the capillary force, making it more difficult for large-diameter particles to precipitate and assemble at the front. An increase in the particle size ratio means a further increase in the size of large particles, thus gradually improving the degree of particle separation.

[0062] Furthermore, this invention does not specifically limit the mass ratio of colloidal quantum dots between different components. Without violating the overall technical concept of this invention, the mass ratio between colloidal quantum dots of different components can be any ratio, and those skilled in the art can make adaptive selections and adjustments according to actual needs.

[0063] In some embodiments, the alkane solvent has 6-10 carbon atoms, such as C6, C7, C8, C9 or C10.

[0064] For example, but not in a limiting sense, the alkane solvents of the present invention may be selected from n-alkane solvents, including but not limited to n-hexane, n-octane, and n-decane.

[0065] In some embodiments, the concentration of the precursor solution is 10 mg / mL to 100 mg / mL, such as 10 mg / mL, 12 mg / mL, 15 mg / mL, 18 mg / mL, 20 mg / mL, 24 mg / mL, 25 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL or 100 mg / mL, etc., preferably 10 mg / mL to 25 mg / mL.

[0066] In this invention, a suitable concentration of the precursor solution is beneficial for diffusion in the silicon-based micropillar template and for forming capillary bridges; further limiting it to 10 mg / mL to 25 mg / mL is more conducive to improving the degree of phase separation and better ensuring the integrity of the assembled structure.

[0067] In some implementations, the precursor solution is placed on the surface of the silicon-based micropillar template by dropwise addition.

[0068] In some embodiments, the height of the silicon-based micropillar template is 5 μm to 15 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm.

[0069] This invention uses silicon-based micropillar templates with a height of 5 μm to 15 μm, which can better form a temperature gradient along the length of the capillary liquid bridge during unidirectional evaporation through the evaporative cooling effect, driving the generation of a stable Marangoni vortex flow; resulting in a multi-component quantum dot heterostructure with more thorough size-oriented phase separation and a more ordered structure.

[0070] Furthermore, the present invention does not specifically limit the morphology and width of the silicon-based micropillar template. Based on the target heterostructure, those skilled in the art can make adaptive selections and adjustments, such as microlines, microrings, or various polygons.

[0071] It is understood that the silicon-based micropillar template in this invention can be purchased commercially or prepared by conventional methods (e.g., using photolithography and reactive ion etching processes to prepare the silicon-based micropillar template). Those skilled in the art can make adaptive selections and adjustments according to actual needs.

[0072] In some implementations, the applied pressure is 1 MPa to 10 MPa, such as 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa.

[0073] In some embodiments, the one-way evaporation process includes:

[0074] Only the evaporation direction of one capillary bridge is retained, while the evaporation directions of the other capillary bridges are sealed.

[0075] It should also be noted that the unidirectional evaporation process in this invention can be carried out at room temperature without the need for additional control of the evaporation temperature.

[0076] Furthermore, the substrate in this invention only needs to meet the requirement of flatness. Without violating the overall technical concept of this invention, any conventional substrate type is applicable to this invention; for example, the substrate includes, but is not limited to, at least one of silicon wafers, glass sheets, quartz sheets, indium tin oxide conductive glass, PDMS, or polyethylene terephthalate and polyimide.

[0077] In some embodiments, the colloidal quantum dots include, but are not limited to, CdSe-based quantum dots, InP-based quantum dots, ZnTeSe-based fluorescent quantum dots, CdSe / ZnCdSe / ZnSeS / ZnS quantum dots, CdZnSe / ZnSe / ZnS quantum dots, CdSe / ZnSe / ZnS-based quantum dots, CdSe / ZnCdSe / ZnS-based quantum dots, PbSe and other infrared quantum dots, perovskite nanocrystals, and oil-soluble quantum dots such as nanosheets; the surface of the colloidal quantum dots may have ligands, which may be selected from oleic acid and / or oleylamine, etc.

[0078] In one embodiment, the present invention provides a multi-component quantum dot heterostructure, which is prepared by the preparation method described in the above embodiments;

[0079] The multi-component quantum dot heterostructure has a size-oriented phase separation structure, which is distributed longitudinally from front to back with increasing particle size, and the multi-component quantum dot heterostructure is arranged in a long-range ordered close-packed pattern.

[0080] The multi-component quantum dot heterostructure provided by this invention has a smooth surface, regular and uniform size, high internal particle assembly order, and excellent photoelectric performance; it can realize the phase separation assembly of two-component, three-component, or even more-component quantum dots, meeting the needs of different optoelectronic devices.

[0081] In some embodiments, the microline width in the long-range ordered close-packed structure of the multi-component quantum dot heterostructure is 2 μm to 10 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0082] In one embodiment, the present invention provides the use of a multi-component quantum dot heterostructure, the use of which includes using the multi-component quantum dot heterostructure described in the above embodiment in optoelectronic devices.

[0083] Example 1

[0084] This embodiment provides a method for preparing a microlinear CdSe-based bicomponent quantum dot heterostructure, the method comprising:

[0085] 1) Provide silicon-based micropillar templates: Micropillar array templates are prepared by photolithography and reactive ion etching. The micropillars are 5 μm high and 2 μm apart, forming a width of 2 μm and a length of 100 μm.

[0086] 2) Preparation of precursor solution: 10.5 nm green CdSe / ZnSe / ZnS quantum dots and 19.8 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots were dispersed in n-octane at a mass ratio of 3:1 to prepare a precursor solution with a concentration of 25 mg / mL.

[0087] 3) Construction of capillary liquid bridge system: 5 μL of precursor solution was dropped onto the surface of silicon-based micropillar template, covered with a flat silicon substrate, and 5 MPa pressure was applied to form micro-linear capillary liquid bridge;

[0088] 4) One-step self-assembly: such as Figure 1 As shown, the system was placed at room temperature (25 °C), with only one end of the capillary bridge exposed to the atmosphere and the other end sealed. This allowed for directional and unidirectional solvent evaporation assembly until complete solvent evaporation, which took approximately 8 hours, yielding the following result: Figure 2 The microlinear bicomponent quantum dot heterostructure shown.

[0089] The CdSe-based bicomponent quantum dot heterostructure obtained in Example 1 of this invention is as follows: Figure 2 As shown, from Figure 2 As can be seen, the preparation method provided by this invention yields a red-green fluorescent heterostructured micron-wire structure with significant separation effect. Green and red quantum dots are orderly stacked and assembled in the front and rear regions of evaporation, respectively, exhibiting a size-oriented phase separation structure. This structure shows a longitudinal phase separation distribution with particle size increasing from the front to the rear, and the multi-component quantum dot heterostructure is arranged in a long-range ordered close-packed configuration.

[0090] Example 2

[0091] This embodiment provides a method for preparing a microring-type CdSe-based two-component quantum dot heterostructure, the method comprising:

[0092] 1) Provide silicon-based micropillar templates: Silicon-based templates with micropillars arranged in a ring are prepared by photolithography and reactive ion etching. The inner diameter of the microrings is 12 μm, the outer diameter is 16 μm, and the height of the micropillars is 5 μm.

[0093] 2) Preparation of precursor solution: 10.5 nm green CdSe / ZnSe / ZnS quantum dots and 19.8 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots were dispersed in n-octane at a mass ratio of 3:1 to prepare a precursor solution with a concentration of 25 mg / mL.

[0094] 3) Construction of capillary liquid bridge system: 5 μL of precursor solution was dropped onto the surface of silicon-based micropillar template, covered with a flat silicon substrate, and 5 MPa pressure was applied to form micro-linear capillary liquid bridge;

[0095] 4) One-step self-assembly: The system was placed at room temperature (25 °C), with only one end of the capillary bridge exposed to the atmosphere and the other end sealed. This allowed for directional and unidirectional solvent evaporation assembly until complete solvent evaporation, taking approximately 8 hours, to obtain the desired product. Figure 3 The microring-type two-component quantum dot heterostructure is shown.

[0096] The CdSe-based bicomponent quantum dot heterostructure obtained in Example 2 of this invention is as follows: Figure 3 As shown, from Figure 3 As can be seen, the preparation method provided by the present invention yields a red-green fluorescent heterogeneous microwire structure with significant separation effect; wherein red and green quantum dots are respectively aggregated on both sides of the microring and are orderly stacked and assembled.

[0097] Example 3

[0098] This embodiment provides a method for preparing a microlinear two-component quantum dot heterostructure, the method comprising:

[0099] 1) Provide silicon-based micropillar templates: Micropillar array templates are prepared by photolithography and reactive ion etching. The micropillars are 15 μm high and 2 μm apart, forming a width of 2 μm and a length of 100 μm.

[0100] 2) Preparation of precursor solution: 10 nm blue CdZnSe / ZnSe / ZnS quantum dots and 19.8 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots were dispersed in n-octane at a mass ratio of 2:1 to prepare a precursor solution with a concentration of 10 mg / mL.

[0101] 3) Construction of capillary liquid bridge system: 5 μL of precursor solution was dropped onto the surface of silicon-based micropillar template, covered with a flat silicon substrate, and 10 MPa pressure was applied to form micro-linear capillary liquid bridges;

[0102] 4) One-step self-assembly: The system was placed at room temperature (25 °C), with only one end of the capillary bridge exposed to the atmosphere and the other end sealed. Solvent-directed and unidirectional evaporation assembly was achieved until complete solvent evaporation, taking approximately 8 hours, resulting in a microlinear bicomponent quantum dot heterostructure, such as... Figure 4 As shown.

[0103] The two-component quantum dot heterostructure obtained in Example 3 of this invention is as follows: Figure 4 As shown, from Figure 4As can be seen, the preparation method provided by this invention yields a blue-red fluorescent heterostructure of micrometers with significant separation effect. Blue and red quantum dots are orderly stacked and assembled in the front and rear regions of evaporation, respectively, exhibiting a size-oriented phase separation structure. This structure shows a longitudinal phase separation distribution with particle size increasing from the front to the rear, and the multi-component quantum dot heterostructure is arranged in a long-range ordered close-packed configuration.

[0104] Example 4

[0105] The difference between this embodiment and embodiment 3 is that in step 2) of this embodiment, the particle size of the blue CdZnSe / ZnSe / ZnSeS / ZnS quantum dots is 18nm, i.e., the particle size ratio is 1.1. Figure 5 As shown.

[0106] All other conditions remain the same as in Example 3.

[0107] The two-component quantum dot structure obtained in Example 4 of this invention is as follows: Figure 5 As shown, from Figure 5 It can be seen that in the preparation method provided by the present invention, the particle size ratio of quantum dots among different components directly affects the effect of size-oriented phase separation. When the particle size ratio is relatively small (<1.9), the size-oriented phase separation is not significant enough and the effect is relatively poor.

[0108] Example 5

[0109] The difference between this embodiment and Embodiment 1 is that in step 2) of this embodiment, the particle size of the green CdSe / ZnSe / ZnS quantum dots is 9 nm, i.e., the particle size ratio is 2.2. Figure 6 As shown.

[0110] All other conditions remain the same as in Example 1.

[0111] The CdSe-based bicomponent quantum dot structure obtained in Example 6 of this invention is as follows: Figure 6 As shown, from Figure 6 As can be seen, the preparation method provided by this invention yields a red-green fluorescent heterostructure microwire with significant separation effect.

[0112] Example 6

[0113] The difference between this embodiment and Embodiment 1 is that in step 2) of this embodiment, the concentration of the precursor solution is 100 mg / mL.

[0114] All other conditions remain the same as in Example 1.

[0115] The CdSe-based bicomponent quantum dot heterostructure obtained in Example 6 of this invention is as follows: Figure 7 As shown, from Figure 7It can be seen that the increased concentration of the precursor solution leads to increased viscosity, resulting in poor particle separation.

[0116] Comparative Example 1

[0117] This comparative example provides a method for preparing a CdSe-based two-component quantum dot structure, the method comprising:

[0118] 1) Preparation of precursor solution: 10.5 nm green CdSe / ZnSe / ZnS quantum dots and 19.8 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots were dispersed in n-octane at a mass ratio of 3:1 to prepare a precursor solution with a concentration of 25 mg / mL.

[0119] 2) The precursor solution is dropped onto a silicon substrate to form unconstrained, sessile droplets, which are then allowed to evaporate naturally at 25 °C to obtain the following... Figure 8 The CdSe-based two-component quantum dot structure is shown.

[0120] The CdSe-based bicomponent quantum dot structure obtained in Comparative Example 1 of this invention is as follows: Figure 8 As shown, from Figure 8 It can be seen that the preparation method provided in Comparative Example 1 produced a coffee ring structure with two quantum dots uniformly mixed; this is because there is no directional capillary fluid in the free droplet, making it impossible to control the transport of the two quantum dots and thus difficult to produce a separation effect.

[0121] Comparative Example 2

[0122] This comparative example provides a method for preparing CdSe-based bicomponent quantum dot structures, the method comprising:

[0123] 1) Preparation of precursor solution: 10.5 nm green CdSe / ZnSe / ZnS quantum dots and 19.8 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots were dispersed in n-octane at a mass ratio of 3:1 to prepare a precursor solution with a concentration of 25 mg / mL.

[0124] 2) The precursor solution was injected into a capillary liquid with an inner diameter of 2 μm and directionally evaporated at 25 °C to obtain the following... Figure 9 The CdSe-based two-component quantum dot structure is shown.

[0125] The CdSe-based bicomponent quantum dot structure obtained in Comparative Example 1 of this invention is as follows: Figure 9 As shown, from Figure 9It can be seen that the microstructure particles assembled in the capillary of Comparative Example 2 have a low degree of particle size separation and the size of the prepared structure is uncontrollable. Since the structure of the capillary does not have gas-liquid interfaces on both sides compared with the capillary liquid bridge, it cannot produce the Marangoni effect and therefore cannot produce a separation effect.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that in step 4), this comparative example does not perform a one-end sealing treatment of the capillary bridge, that is, it performs a non-unidirectional evaporation treatment of the capillary bridge, but a free evaporation treatment.

[0128] All other conditions remain the same as in Example 1.

[0129] Figure 10 The following is a fluorescence microscope image of the two-component quantum dot structure prepared by the preparation method provided in Comparative Example 3 of the present invention; as shown. Figure 10 As shown, the particles in the micron-line array are separated in opposite directions within the micron-line and do not maintain consistency, which is not conducive to the fabrication of large-area controllable microfabrication.

[0130] Application Example 1

[0131] This application example provides a method for using multi-component quantum dot heterostructures in dual-wavelength laser photonic integrated circuits, the method comprising:

[0132] S1. Preparation of multi-component quantum dot heterostructures:

[0133] A micropillar array template containing one micrometer line and two micrometer rings is provided. The parameters of the micrometer line are: micropillar height 5 μm, micropillar spacing 2 μm, forming width 2 μm and length 100 μm; the parameters of the micrometer rings are: microring inner diameter 12 μm, microring outer diameter 16 μm, micropillar height 5 μm.

[0134] A precursor solution with a concentration of 25 mg / mL was prepared by dispersing 10 nm green CdSe / ZnSe / ZnS quantum dots and 19 nm red CdSe / ZnCdSe / ZnSeS / ZnS quantum dots in n-octane at a mass ratio of 6:1.

[0135] Using the same steps 3) and 4) as in Example 1, a result is obtained as follows: Figure 11 The image shows a ring-shaped green quantum dot-dominated structure, and another optical microstructure (quantum dot heterostructure) enriched with red quantum dots.

[0136] S2. Device packaging: Diluted fluoropolymer of type CYTOP is spin-coated onto the surface of the heterostructure, and vacuum dried to form a protective layer, forming a dual-wavelength laser photonic integrated circuit;

[0137] S3. Laser Performance Testing: Using a 400 nm femtosecond pulsed laser (repetition frequency 1 kHz, pulse width 100 fs) as the excitation source, the green and red quantum dot phase regions of the microring in the dual-wavelength laser photonic integrated circuit were excited respectively. The laser signal was detected at the output end of the optical waveguide, and the results were obtained as follows: Figure 12 The test results are shown.

[0138] like Figure 12 As shown, the green laser threshold is 2.7 μJ / cm. 2 Linewidth 0.23 nm, Q value 2160; red laser threshold 4.0 μJ / cm 2 The linewidth is 0.18 nm and the Q value is 4260. The dual-wavelength laser can be directionally transmitted in the optical waveguide. After 1 hour of pulsed laser excitation, the PL intensity of the green and red lasers still maintains 91% and 85% of the initial values, respectively, showing good stability. By exciting different resonant cavities, green laser, red laser, and red plus green laser can be collected at the output end of the waveguide.

[0139] Application Example 2

[0140] This application example provides a method for using multi-component quantum dot heterostructures in high-resolution full-color LED display devices, the method comprising:

[0141] S1. Preparation of multi-component quantum dot heterostructures:

[0142] A silicon-based micropillar template containing micrometer-long wires with a width of 2 μm is provided; a precursor solution with a concentration of 25 mg / mL is prepared by using 6 nm blue quantum dots (CdZnSe / ZnSe / ZnS), 10 nm green quantum dots (CdSe / ZnSe / ZnS), and 19 nm red quantum dots (CdSe / ZnCdSe / ZnSeS / ZnS) in a mass ratio of 7:3:1 and n-octane as the solvent;

[0143] Substrate pixel pit fabrication: ITO (indium tin oxide) glass was cleaned and then cleaned with O2 plasma. PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, 3000 r / s) was then spin-coated and annealed at 150 °C for 10 minutes. The pixel pit locations were lithographically marked using negative photoresist for quantum dot deposition. A hole transport layer (TFB) was then spin-coated onto the lithographically marked substrate. A silicon-based micropillar template was aligned with the pixel pit locations under a microscope, a precursor solution was added, and a pressure of 5 MPa was applied. The same self-assembly method as in Example 1 was used. After the solvent had completely evaporated, the template was removed, allowing the three-color quantum dots to be deposited at the target locations.

[0144] S2. Device fabrication: After complete quantum dot deposition, spin-coat the electron transport layer ZnMgO; evaporate metallic aluminum using thermal evaporation equipment; encapsulate with encapsulating adhesive and age for 24 hours to form the display device;

[0145] 3) LED luminous performance characterization: The display device was powered by a DC power supply of 5V, and then the prepared microstructure was observed under a microscope. Specific results are as follows: Figure 13 As shown.

[0146] like Figure 13 As shown in the figure, the display device of Application Example 2 is prepared with red, green and blue pixel areas exhibiting distinct three primary color light emission, uniform light emission intensity, large size area, and the device as a whole exhibiting warm white light emission.

[0147] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a multi-component quantum dot heterostructure, characterized in that, The preparation method includes the following steps: At least two types of colloidal quantum dots are dispersed in an alkane solvent to obtain a precursor solution; The precursor solution is placed on the surface of a silicon-based micropillar template, and then a substrate is covered on the top of the silicon-based micropillar template. Pressure is applied so that the precursor solution forms a capillary bridge between the top of the silicon-based micropillar template and the substrate. The capillary liquid bridge structure is subjected to unidirectional evaporation to form a multi-component quantum dot heterostructure with size-oriented phase separation. The particle size of colloidal quantum dots of any component is different from that of colloidal quantum dots of other components.

2. The preparation method according to claim 1, characterized in that, In the at least two-component colloidal quantum dots, the particle size ratio between the particle size of each colloidal quantum dot and the particle size of the other colloidal quantum dot is ≥1.1, preferably ≥1.

9.

3. The preparation method according to claim 1, characterized in that, The alkane solvent has 6-10 carbon atoms.

4. The preparation method according to claim 1, characterized in that, The concentration of the precursor solution is 10 mg / mL to 100 mg / mL, preferably 10 mg / mL to 25 mg / mL.

5. The preparation method according to claim 1, characterized in that, The precursor solution was placed on the surface of the silicon-based micropillar template by dropwise addition. Preferably, the height of the silicon-based micropillar template is 5 μm to 15 μm.

6. The preparation method according to claim 1, characterized in that, The applied pressure is 1 MPa to 10 MPa.

7. The preparation method according to claim 1, characterized in that, The method for unidirectional evaporation includes: Only the evaporation direction of one capillary bridge is retained, while the evaporation directions of the other capillary bridges are sealed.

8. A multi-component quantum dot heterostructure, characterized in that, The multi-component quantum dot heterostructure is prepared by the preparation method according to any one of claims 1-7; The multi-component quantum dot heterostructure has a size-oriented phase separation structure, which is distributed longitudinally from front to back with increasing particle size, and the multi-component quantum dot heterostructure is arranged in a long-range ordered close-packed pattern.

9. The multi-component quantum dot heterostructure according to claim 8, characterized in that, The micro-line width in the long-range ordered close-packed structure of the multi-component quantum dot heterostructure is 2 μm to 10 μm.

10. An application of a multi-component quantum dot heterostructure, characterized in that, The applications include using the multi-component quantum dot heterostructure as described in claim 8 or 9 in optoelectronic devices.

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