A method for patterning the preparation of a stacked heterostructure array

Abstract

The present invention provides a method for patterning and preparing a stacked heterostructure array. First, a first-layer patterned colloidal quantum dot (CQD) micro-nano array is prepared by using a first-level capillary liquid bridge. Then, a three-dimensional transfer platform is used to align the second-layer silicon micro-column template with the first-layer patterned substrate in an arbitrarily adjustable direction, and a precursor solution of the second-layer colloidal quantum dots (CQDs) is dropped to grow the second-layer colloidal quantum dot array by using a second-level capillary liquid bridge, thereby obtaining a patterned stacked heterostructure array. The present invention uses the directional dewetting process of the first-level capillary liquid bridge to induce the growth of the first-layer colloidal quantum dots, obtaining a high-quality one-dimensional colloidal quantum dot array with a flat surface. Then, its original oleic acid ligand is exchanged for a mercaptopropionic acid ligand, and a method for inducing the assembly of the second-layer colloidal quantum dots by using a second-level capillary liquid bridge is further adopted. The present invention can obtain heterostructures with arbitrary and tunable overlapping positions, providing a new idea for patterning and preparing stacked heterostructures.

Description

Technical Field

[0001] The present invention relates to the technical field of basic electrical components, and particularly to a method for patterning and preparing a stacked heterostructure array. Background Art

[0002] Function materials that can be processed in liquid phase have been widely studied in optoelectronics, including polymers, organic small molecules, colloidal nanoparticles, and metal halide perovskites, because they have advantages such as a designable energy band structure, long-range order, low cost, and easy processing. Heterostructures combine multiple optoelectronic function materials and can be used to prepare micro / nano devices with multiple functions and high performance, such as bipolar field-effect transistors, memory devices, field-effect tunneling transistors, and multicolor displays. For the patterning of single-component semiconductor materials, liquid-phase processing methods for single-component micro / nano structures have been realized, but there are still great challenges in the preparation of high-quality layered heterostructures. To solve these problems, one-step and multi-step methods have been developed to pattern heterostructures. The one-step method is to dissolve two different substances in the same solvent. Due to different solubilities, the order of solute precipitation is also different. An issue that cannot be ignored is that the universality of the one-step method is relatively low, and few materials can be dissolved in the same solvent to perform spontaneous precipitation with a controllable crystal orientation. The multi-step strategy is to separately prepare the second layer of material after preparing the first layer of material, which can effectively avoid the disadvantages of the one-step strategy. Therefore, it is of great scientific significance and industrial value to develop a universal two-step method for patterning and preparing a stacked heterostructure array. Summary of the Invention

[0003] The present invention aims to solve the problem of patterning and preparing a stacked heterostructure array, and provides a method for patterning and preparing a stacked heterostructure array. By designing circular silicon pillar templates with different sizes, spacings, and morphologies, FAS molecules are selectively modified to make their tops hydrophilic and sidewalls hydrophobic to control the formation of capillary liquid bridges. Thus, the growth of the first layer of colloidal quantum dots is induced by the directional dewetting process of the primary capillary liquid bridge, and a high-quality one-dimensional colloidal quantum dot array with a flat surface is obtained. The original oleic acid ligand is exchanged with a mercaptopropionic acid ligand, and a method for inducing the assembly of the second layer of colloidal quantum dots by using a secondary capillary liquid bridge is further adopted. By using a three-dimensional transfer platform, the lateral distance between the two layers of colloidal quantum dots can be controlled, and a heterostructure with an arbitrary and tunable overlapping position can be obtained.

[0004] The present invention provides a method for patterning and preparing a stacked heterostructure array, comprising the following steps:

[0005] S1. Prepare the first structural array: Use a first-level capillary liquid bridge to assemble single-component colloidal quantum dots. After dewetting, the first structural array is obtained. The pattern and size of the first structural array are controlled by the shape of the silicon pillar template of the first structural array. The silicon pillar template of the first structural array is asymmetrically wettable. The silicon pillar template of the first structural array includes at least two silicon pillars. The single-component colloidal quantum dots are modified with a first ligand.

[0006] S2. Ligand exchange: Exchange the first ligand in the first structural array for a second ligand, and the second ligand is used to protect the first structural array from being dissolved during the preparation process of the next stacked heterostructure array.

[0007] S3. Prepare a patterned stacked heterostructure array: Use a second-level capillary liquid bridge to prepare a second structural array on the upper surface of the first structural array. Use a three-dimensional transfer platform to control the positional relationship between the first structural array and the silicon pillar template of the second structural array, so that the position between the first layer of colloidal quantum dots of the first structural array and the second layer of colloidal quantum dots to be formed by the silicon pillar template of the second structural array is fixed. The pattern and size of the second structural array are controlled by the shape of the silicon pillar template of the second structural array. The silicon pillar template of the second structural array is asymmetrically wettable. The silicon pillar template of the second structural array includes at least two silicon pillars. After dewetting, a patterned stacked heterostructure array is obtained.

[0008] A method for patterning and preparing a stacked heterostructure array according to the present invention, as a preferred embodiment, further includes the following steps:

[0009] S4. Perform ligand exchange again, and repeat the preparation of the patterned stacked heterostructure array n times. The preparation of the patterned stacked heterostructure array is completed. The stacked heterostructure array includes n + 2 structural arrays, where n > 0.

[0010] A method for patterning and preparing a stacked heterostructure array according to the present invention, as a preferred embodiment, in step S1, the method for forming the first-level capillary liquid bridge is: Drop a first semiconductor material precursor solution on the silicon pillar template of the first structural array, and cover the substrate above the silicon pillar template of the first structural array to form a first sandwich structure. The top of the silicon pillar template of the first structural array is hydrophilic and the side wall is hydrophobic. The top of the silicon pillar template of the first structural array, the first semiconductor material precursor solution, and the substrate form a first-level capillary liquid bridge.

[0011] The first-level capillary liquid bridge is a micron-scale capillary bridge with a height of 500 - 1000 nm. The first semiconductor material precursor solution is a single-component colloidal quantum dot solution.

[0012] The silicon pillar template of the first structural array is processed by photolithography and etching, and the silicon pillar template of the first structural array is modified with FAS.

[0013] A method for patterning and preparing a stacked heterostructure array according to the present invention. As a preferred method, the ligand exchange method is the soaking method or the spin coating method.

[0014] The soaking method includes the following steps: soaking the first sandwich structure in the second ligand solution for 5 to 30 minutes, then rinsing with the solvent in the second ligand solution, placing it in an oven at 30 to 90 °C and heating for 6 to 24 hours to remove the excess solvent, and the ligand exchange is completed.

[0015] The spin coating method includes the following steps: spin coating the second ligand solution on the first structure array at a rotation speed of 1500 rmp, then soaking it in the solvent in the second ligand solution, and heating at 40 to 80 °C to remove the excess solvent.

[0016] A method for patterning and preparing a stacked heterostructure array according to the present invention. As a preferred method, the solvent is toluene or chlorobenzene, the mass fraction of the second ligand solution is 5%, and the volume of the second ligand solution in the spin coating method is 10 μl.

[0017] A method for patterning and preparing a stacked heterostructure array according to the present invention. As a preferred method, in step S3, the method for forming the secondary capillary liquid bridge is as follows: dropping the second semiconductor material precursor solution on the silicon pillar template of the second structure array, and covering the first structure array above the silicon pillar template of the second structure array to form a second sandwich structure. The top of the silicon pillar template of the second structure array is hydrophilic and the side wall is hydrophobic. Using a three-dimensional transfer platform to control the positional relationship between the first structure array and the silicon pillar template of the second structure array, so that the position between the first layer of colloidal quantum dots of the first structure array and the second layer of colloidal quantum dots to be formed by the silicon pillar template of the second structure array is fixed. The top of the silicon pillar template of the second structure array, the second semiconductor material precursor solution and the second structure array form a secondary capillary liquid bridge.

[0018] The silicon pillar template of the second structure array is processed by photolithography and etching, and the silicon pillar template of the second structure array is modified with FAS.

[0019] A method for patterning and preparing a stacked heterostructure array according to the present invention. As a preferred method, in step S2, the first ligand is oleic acid, and the second ligand is any one of the following: mercaptopropionic acid, ethylenediamine, and 1,2-ethanedithiol.

[0020] In step S3, the silicon pillar template of the second structure array can be the same as the silicon pillar template of the first structure array.

[0021] The ligand exchange in step S4 refers to the mutual exchange between the first ligand and the second ligand.

[0022] In a method for patterning and preparing a stacked heterostructure array according to the present invention, as a preferred embodiment, in step S1, the first semiconductor material precursor solution is any one of the following: CdSe-based quantum dot precursor solution, Cu2S, CuInSe2-based quantum dot precursor solution, and PbS-based quantum dot precursor solution, and the solvent of the first semiconductor material precursor solution is toluene or chlorobenzene;

[0023] The substrate is any one of the following: silicon wafer, silicon dioxide wafer, quartz wafer, glass wafer, and indium tin oxide conductive glass. Before preparation, the substrate is washed clean and dried with nitrogen.

[0024] In a method for patterning and preparing a stacked heterostructure array according to the present invention, as a preferred embodiment, in step S2, the second semiconductor material precursor solution is any one of the following: CdSe-based quantum dot precursor solution, Cu2S, CuInSe2-based quantum dot precursor solution, and PbS-based quantum dot precursor solution, and the solvent of the second semiconductor material precursor solution is toluene or chlorobenzene.

[0025] In a method for patterning and preparing a stacked heterostructure array according to the present invention, as a preferred embodiment, in steps S1 and S3, the shapes of the first structural array silicon pillar template and the second structural array silicon pillar template are both any one of the following: linear array, curved array, circular array, square array, and triangular array.

[0026] The present invention adopts the following technical solutions:

[0027] A method for patterning and preparing a stacked heterostructure array includes the following steps:

[0028] First, a one-dimensional array with controllable patterns and sizes is prepared by assembling single-component colloidal quantum dots using a first-level capillary liquid bridge. The surface of the array is smooth and the arrangement is neat. Then, a stacked heterostructure array is prepared using a multi-level capillary liquid bridge. On the basis of successfully preparing the first layer of colloidal quantum dots, the ligand exchange is carried out, and the three-dimensional transfer platform can be used to control the positional relationship between the first layer of colloidal quantum dots and the second layer of colloidal quantum dots, forming a patterned stacked heterostructure array.

[0029] At present, the method of preparing a monolayer semiconductor material array by liquid-phase processing has become mature. Therefore, it is crucial to pattern and prepare a stacked heterostructure array by a fully liquid-phase processing method. Specifically, the liquid-phase processing methods for patterning and preparing stacked heterojunctions can generally be divided into a one-step method and a two-step method. In the one-step method, two different semiconductor materials are dissolved in the same solvent and crystallize separately to form a heterostructure; in the two-step method, first, an array of one semiconductor material is grown, and then the second layer of material is grown separately on the pre-formed first layer of material or the grown second layer of material is transferred onto the first layer of material. Therefore, we have developed a general method for patterning and preparing a stacked heterostructure array by ligand exchange. Our method provides a new route for preparing high-quality stacked heterostructure arrays.

[0030] Preferably, by using photolithography and etching processes, a mask template with different patterns and sizes can be designed to prepare a patterned silicon microcolumn template with corresponding patterns and sizes.

[0031] Preferably, the silicon microcolumn template has asymmetric wettability. The top of the silicon microcolumn template modified with FAS is hydrophilic and the sidewall is hydrophobic. FAS is perfluorodecyltrichlorosiloxane.

[0032] Preferably, the liquid of the secondary capillary liquid bridge should not dissolve or damage the morphology and quality of the first layer of colloidal quantum dots.

[0033] Preferably, the substrate is selected from one of a silicon wafer, a silicon dioxide wafer, a quartz wafer, a glass wafer, and indium tin oxide conductive glass, and is cleaned and dried with nitrogen.

[0034] Preferably, a three-dimensional transfer platform can be used to control the lateral distance between two layers of semiconductor materials to obtain a heterostructure with an arbitrary and tunable overlapping position.

[0035] Define the colloidal quantum dot solution as the precursor solution, including but not limited to CdSe-based quantum dots, Cu2S, CuInSe2-based quantum dots, PbS-based quantum dots, etc. The experimental scheme in this patent example is for CdSe / ZnS quantum dots with toluene as the solvent and a concentration of 100 mg / ml.

[0036] Ligands include but not limited to common ligands such as mercaptopropionic acid, ethylenediamine (EDA), and 1,2-ethanedithiol (EDT).

[0037] Ligand exchange is carried out by the immersion method. Immerse the CdSe / ZnS quantum dot sandwich structure in a 5% mass fraction mercaptopropionic acid / methanol solution for 10 min, then rinse with methanol solution, and place it in an oven at 60 °C for 10 h to remove the excess methanol.

[0038] In addition to the immersion method, the ligand exchange can also be carried out by spin coating. Spin coat 10 μl of a 5% mass fraction of mercaptopropionic acid / methanol solution on the quantum dot array at a rotation speed of 1500 rmp, and then immerse it in a methanol solution, and heat it at 60 °C to remove the excess methanol.

[0039] The oven heating temperature can be set to 30 - 70 °C, and the heating time range is adjusted according to the temperature change. It takes 24 h at 30 °C and 6 h at 70 °C. The toluene solvent should not exceed 70 °C. The oven temperature can be set according to different solvents. The temperature for chlorobenzene should be set at 60 - 90 °C.

[0040] According to this method, a stacked heterostructure with three or more layers can be prepared by simply repeating the ligand exchange and patterning processes.

[0041] The present invention has the following advantages:

[0042] (1) The present invention first uses a primary capillary liquid bridge to prepare a patterned array of the first layer of colloidal quantum dots. Assemble the target substrate, a silicon microcolumn template modified with FAS (the top is hydrophilic and the sidewall is hydrophobic), and the precursor solution of the first layer of semiconductor material into a sandwich structure. The primary capillary liquid bridge can induce the directional dewetting process of the first layer of material, and a strictly aligned and neatly arranged patterned one-dimensional array can be prepared. Then, by exchanging its ligands, the original oleic acid ligands are transformed into mercaptopropionic acid ligands, which can ensure that the quantum dots in the first layer are not damaged during the secondary dewetting process. Further, a similar sandwich assembly system is used with a secondary capillary liquid bridge to grow a patterned array of the second layer of colloidal quantum dots, and a patterned stacked heterostructure array can be obtained. This preparation method provides a new idea for the patterned preparation of stacked heterostructures.

[0043] (2) The existing technologies using the one-step method have relatively harsh usage conditions, and there will be mutual interference during the precipitation and assembly of the mixture of the two materials. However, the present invention uses ligand exchange to first grow a micro-nano structure of one kind of colloidal quantum dots, exchanges its ligands to protect the structure array from being damaged, and then prepares another colloidal quantum dot on top of the former, solving the problem of mutual interference.

[0044] (3) The present invention can prepare a patterned array according to a mask template with a designable pattern and size.

[0045] (4) The present invention uses a three-dimensional transfer platform to arbitrarily and precisely control the horizontal distance between the two layers of materials to form different stacked heterostructure arrays. Description of the Drawings

[0046] Figure 1 It is a flowchart of a method for patterning and preparing a stacked heterostructure array;

[0047] Figure 2Schematic diagram of the preparation process of the first structure array for a method of patterning and preparing a stacked heterostructure array;

[0048] Figure 3 Schematic diagram of the preparation process of the second structure array for a method of patterning and preparing a stacked heterostructure array;

[0049] Figure 4 Schematic diagram of the preparation process of the third structure array for a method of patterning and preparing a stacked heterostructure array;

[0050] Figure 5 Dark-field fluorescence microscopy image of a patterned and controllable-spacing stacked red CQDs / blue CQDs heterostructure array prepared by a method of patterning and preparing a stacked heterostructure array;

[0051] Figure 6 Dark-field fluorescence microscopy image of a patterned and controllable-spacing stacked green CQDs / red CQDs heterostructure array prepared by a method of patterning and preparing a stacked heterostructure array;

[0052] Figure 7 Dark-field fluorescence microscopy image of a patterned and controllable-spacing stacked red CQDs / blue CQDs heterostructure array prepared by a method of patterning and preparing a stacked heterostructure array. Detailed implementation mode

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0054] Example 1

[0055] As Figure 1 shown, a method of patterning and preparing a stacked heterostructure array includes the following steps:

[0056] S1. Prepare the first structure array: As Figure 2 shown, a one-level capillary liquid bridge is used to assemble a single-component colloidal quantum dot. After dewetting, the first structure array is obtained. The pattern and size of the first structure array are controlled by the shape of the first structure array silicon pillar template. The first structure array silicon pillar template is asymmetrically wetted. The first structure array silicon pillar template includes at least two silicon pillars. The single-component colloidal quantum dot is modified with a first ligand;

[0057] The formation method of the first-level capillary liquid bridge is as follows: Drop the first semiconductor material precursor solution on the first structural array silicon pillar template, and cover the substrate above the first structural array silicon pillar template to form a first sandwich structure. The top of the first structural array silicon pillar template is hydrophilic and the side wall is hydrophobic. The top of the first structural array silicon pillar template, the first semiconductor material precursor solution and the substrate form a first-level capillary liquid bridge;

[0058] The first-level capillary liquid bridge is a micron-scale capillary bridge with a height of 500-1000 nm, and the first semiconductor material precursor solution is a single-component colloidal quantum dot solution;

[0059] The first structural array silicon pillar template is processed by photolithography and etching, and the first structural array silicon pillar template is modified with FAS;

[0060] The first semiconductor material precursor solution is any one of the following: CdSe-based quantum dot precursor solution, Cu2S, CuInSe2-based quantum dot precursor solution, and PbS-based quantum dot precursor solution. The solvent of the first semiconductor material precursor solution is toluene or chlorobenzene;

[0061] The substrate is any one of the following: silicon wafer, silicon dioxide wafer, quartz wafer, glass wafer, and indium tin oxide conductive glass. Before preparation, the substrate is washed clean and dried with nitrogen;

[0062] S2. Ligand exchange: Exchange the first ligand in the first structural array for the second ligand, and the second ligand is used to protect the first structural array from being dissolved during the preparation of the next stacked heterostructure array;

[0063] The method of ligand exchange is the immersion method or the spin coating method.

[0064] The immersion method includes the following steps: Immerse the first sandwich structure in the second ligand solution for 5-30 minutes, then rinse with the solvent in the second ligand solution, put it in an oven at 30-90 °C and heat for 6-24 hours to remove the excess solvent, and the ligand exchange is completed;

[0065] The spin coating method includes the following steps: Spin coat the second ligand solution on the first structural array at a speed of 1500 rmp, then immerse it in the solvent in the second ligand solution, and heat at 40-80 °C to remove the excess solvent;

[0066] The solvent is toluene or chlorobenzene, the mass fraction of the second ligand solution is 5%, and the volume of the second ligand solution in the spin coating method is 10 ul;

[0067] The first ligand is oleic acid, and the second ligand is any one of the following: mercaptopropionic acid, ethylenediamine, and 1,2-ethanedithiol;

[0068] S3. Prepare a patterned stacked heterostructure array: As Figure 3As shown, a second structural array is prepared using a secondary capillary liquid bridge on the upper surface of the first structural array. The three-dimensional transfer platform is used to control the positional relationship between the first structural array and the silicon pillar template of the second structural array, so that the position between the first layer of colloidal quantum dots of the first structural array and the second layer of colloidal quantum dots that will be formed by the silicon pillar template of the second structural array is fixed. The pattern and size of the second structural array are controlled by the shape of the silicon pillar template of the second structural array. The silicon pillar template of the second structural array has asymmetric wetting. The silicon pillar template of the second structural array includes at least two silicon pillars. After dewetting, a patterned stacked heterostructure array is obtained.

[0069] The formation method of the secondary capillary liquid bridge is as follows: Drop the second semiconductor material precursor solution on the silicon pillar template of the second structural array, and cover the first structural array above the silicon pillar template of the second structural array to form a second sandwich structure. The top of the silicon pillar template of the second structural array is hydrophilic and the side walls are hydrophobic. The three-dimensional transfer platform is used to control the positional relationship between the first structural array and the silicon pillar template of the second structural array, so that the position between the first layer of colloidal quantum dots of the first structural array and the second layer of colloidal quantum dots that will be formed by the silicon pillar template of the second structural array is fixed. The top of the silicon pillar template of the second structural array, the second semiconductor material precursor solution, and the first structural array form a secondary capillary liquid bridge.

[0070] The silicon pillar template of the second structural array is processed using photolithography and etching, and the silicon pillar template of the second structural array is modified using FAS.

[0071] The silicon pillar template of the second structural array can be the same as or different from the silicon pillar template of the first structural array.

[0072] The second semiconductor material precursor solution is any one of the following: CdSe-based quantum dot precursor solution, Cu2S, CuInSe2-based quantum dot precursor solution, and PbS-based quantum dot precursor solution. The solvent of the second semiconductor material precursor solution is toluene or chlorobenzene.

[0073] The shapes of the silicon pillar templates of the first structural array and the second structural array are any one of the following: linear array, curved array, circular array, square array, and triangular array.

[0074] S4. Perform ligand exchange again, as Figure 4 As shown, repeat the preparation of the patterned stacked heterostructure array n times. The preparation of the patterned stacked heterostructure array is completed. The stacked heterostructure array includes n + 2 layers of structural arrays, where n > 0.

[0075] Ligand exchange refers to the mutual exchange between the first ligand and the second ligand.

[0076] Example 2

[0077] As Figure 1As shown, a method for patterning and preparing a stacked heterostructure array includes the following steps:

[0078] 1) Ultrasonic clean the silicon substrate with ethanol, acetone, and isopropyl alcohol solutions for 15 minutes respectively. After cleaning, dry it with nitrogen and set it aside for later use.

[0079] 2) As Figure 2 shown, on a silicon microcolumn template with asymmetric wettability, drop 7 μL of the precursor solution of blue quantum dots, and cover it with the silicon substrate to form a sandwich structure. The silicon column template consists of three closely connected rings of different sizes.

[0080] 3) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0081] 4) Gently disassemble the sandwich structure, and a blue light quantum dot array is successfully prepared on the silicon substrate. The silicon column template can be reused to grow the same material.

[0082] 5) By exchanging its ligands, the original oleic acid ligands are transformed into mercaptopropionic acid ligands, which can ensure the protection of the quantum dots in the first layer from being dissolved during the secondary dewetting process.

[0083] 6) As Figure 3 shown, on a new silicon microcolumn template, drop 7 μL of the precursor solution of red light quantum dots, and use a three-dimensional transfer platform to precisely control the horizontal coverage angle between the silicon substrate and the silicon column in step 5) to form a new sandwich structure. The silicon column template is the same as that in step 2).

[0084] 7) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0085] 8) Gently disassemble the sandwich structure, and a stacked red CQDs / blue CQDs heterostructure array is successfully prepared on the silicon substrate, as Figure 5 .

[0086] 9) As Figure 4 shown, if a stacked heterostructure with three or more layers needs to be prepared, only repeat steps 5)-8) for ligand exchange and patterning.

[0087] In this embodiment, through a silicon column template with a specific designed pattern and size, a threshold space for the directional flow of the precursor solution of colloidal quantum dots is provided. As the solvent evaporates, the first-level capillary liquid bridge induces the directional dewetting of blue CQDs, and then a neatly arranged blue CQDs array is obtained. On the top of this blue CQDs array, the second-level capillary liquid bridge induces the directional dewetting of red CQDs to obtain a patterned stacked red CQDs / blue CQDs heterostructure array.

[0088] Example 3

[0089] As Figure 1 shown, a method for patterning and preparing a stacked heterostructure array includes the following steps:

[0090] 1) Ultrasonically clean the silicon substrate with ethanol, acetone, and isopropyl alcohol solutions for 15 minutes each. After cleaning, dry it with nitrogen and set it aside for later use.

[0091] 2) Drop 7 μL of the precursor solution of red-light colloidal quantum dots (CQDs) on the silicon microcolumn template with asymmetric wettability, and cover it with the silicon substrate to form a sandwich structure. The silicon column template is a separate circular ring array with a diameter of 5 μm.

[0092] 3) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0093] 4) Gently disassemble the sandwich structure, and a red-light quantum dot array is successfully prepared on the silicon substrate. The silicon column template can be reused to grow the same material.

[0094] 5) By exchanging its ligands, the original oleic acid ligand is transformed into a mercaptopropionic acid ligand, which can ensure the protection of the quantum dots in the first layer from being dissolved during the secondary dewetting process.

[0095] 6) Drop 7 μL of the precursor solution of green-light quantum dots on the new silicon microcolumn template, and use a three-dimensional transfer platform to precisely control the horizontal coverage angle between the silicon substrate and the silicon column in step 5) to form a new sandwich structure. The silicon column template is the same as in 2).

[0096] 7) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0097] 8) Gently disassemble the sandwich structure, and a stacked green CQDs / red CQDs heterostructure array is successfully prepared on the silicon substrate, as Figure 6 .

[0098] In this example, through a silicon column template with a specific design pattern and size, a threshold space for the directional flow of the precursor solution of colloidal quantum dots is provided. As the solvent evaporates, the first-level capillary liquid bridge induces the directional dewetting of red CQDs, and thus a neatly arranged red CQDs array is obtained. On top of this red CQDs array, the second-level capillary liquid bridge induces the directional dewetting of green CQDs to obtain a patterned stacked green CQDs / red CQDs heterostructure array.

[0099] Example 4

[0100] As Figure 1As shown, a method for patterning and preparing a stacked heterostructure array includes the following steps:

[0101] 1) Ultrasonic clean the silicon substrate with ethanol, acetone, and isopropyl alcohol solutions for 15 minutes respectively. After cleaning, dry it with nitrogen and set it aside for later use.

[0102] 2) Drop 7 μL of the precursor solution of blue light colloidal quantum dots (CQDs) on the silicon microcolumn template with asymmetric wettability, and cover it with the silicon substrate to form a sandwich structure. The silicon column template is a separate square ring array with a diameter of 10 μm.

[0103] 3) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0104] 4) Gently disassemble the sandwich structure, and the blue light quantum dot ring array is successfully prepared on the silicon substrate. The silicon column template can be reused to grow the same material.

[0105] 5) By exchanging its ligands, the original oleic acid ligand is transformed into a mercaptopropionic acid ligand, which can ensure the protection of the quantum dots in the first layer from being dissolved during the secondary dewetting process.

[0106] 6) Drop 7 μL of the precursor solution of red light quantum dots on the new silicon microcolumn template, and precisely control the horizontal coverage angle between the silicon substrate and the silicon column in step 5) using a three-dimensional transfer platform to form a new sandwich structure. The silicon column template is a separate hexagonal ring array with a diameter of 10 μm.

[0107] 7) Place the sandwich structure system in an oven at 70 °C and heat it for 12 h. Take it out after the solvent has completely evaporated.

[0108] 8) Gently disassemble the sandwich structure, and the stacked red light CQDs / blue light CQDs heterostructure array is successfully prepared on the silicon substrate, as Figure 7 .

[0109] In this embodiment, through a silicon column template with a specific designed pattern and size, a threshold space for the directional flow of the precursor solution of colloidal quantum dots is provided. As the solvent evaporates, the primary capillary liquid bridge induces the directional dewetting of blue light CQDs, and then a neatly arranged blue light CQDs array is obtained. On the top of this blue light CQDs array, the secondary capillary liquid bridge induces the directional dewetting of red light CQDs to obtain a patterned stacked red light CQDs / blue light CQDs heterostructure array.

[0110] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A method for patterning and preparing a stacked heterostructure array, characterized in that: It includes the following steps: S1. Prepare the first structure array: Use a first-level capillary liquid bridge to assemble single-component colloidal quantum dots, and obtain the first structure array after dewetting. The pattern and size of the first structure array are controlled by the shape of the first structure array silicon pillar template. The first structure array silicon pillar template is asymmetrically wetted. The first structure array silicon pillar template includes at least two silicon pillars. The single-component colloidal quantum dots are modified with a first ligand; The method for forming the first-level capillary liquid bridge is: Drop a first semiconductor material precursor solution on the first structure array silicon pillar template, and cover the substrate above the first structure array silicon pillar template to form a first sandwich structure. The top of the first structure array silicon pillar template is hydrophilic and the side wall is hydrophobic. The top of the first structure array silicon pillar template, the first semiconductor material precursor solution, and the substrate form the first-level capillary liquid bridge; The first semiconductor material precursor solution is a CdSe / ZnS quantum dot precursor solution. The solvent of the first semiconductor material precursor solution is toluene or chlorobenzene. The first ligand is oleic acid; S2. Ligand exchange: Exchange the first ligand in the first structure array for a second ligand. The second ligand is used to protect the first structure array from being dissolved during the preparation of the next stacked heterostructure array; The method for ligand exchange is the soaking method or the spin-coating method; The soaking method includes the following steps: Soak the first sandwich structure in the second ligand solution for 5 to 30 minutes, then rinse with the solvent in the second ligand solution, and place it in an oven at 30 to 90 °C and heat for 6 to 24 hours to remove the excess solvent, and the ligand exchange is completed; The spin-coating method includes the following steps: Spin-coat the second ligand solution on the first structure array at a speed of 1500 rmp, then soak it in the solvent in the second ligand solution, and heat at 40 to 80 °C to remove the excess solvent; The second ligand is any one of the following: mercaptopropionic acid, ethylenediamine, and 1,2-ethanedithiol; S3. Prepare a patterned stacked heterostructure array: Use a second-level capillary liquid bridge to prepare a second structure array on the upper surface of the first structure array. Use a three-dimensional transfer platform to control the positional relationship between the first structure array and the second structure array silicon pillar template, so that the position between the first layer of colloidal quantum dots of the first structure array and the second layer of colloidal quantum dots to be formed by the second structure array silicon pillar template is fixed. The pattern and size of the second structure array are controlled by the shape of the second structure array silicon pillar template. The second structure array silicon pillar template is asymmetrically wetted. The second structure array silicon pillar template includes at least two silicon pillars; The method for forming the secondary capillary liquid bridge is as follows: Drop the second semiconductor material precursor solution on the second structural array silicon pillar template, and cover the first structural array above the second structural array silicon pillar template to form a second sandwich structure. The top of the second structural array silicon pillar template is hydrophilic and the side wall is hydrophobic. Use the three-dimensional transfer platform to control the positional relationship between the first structural array and the second structural array silicon pillar template, so that the position between the first layer of colloidal quantum dots of the first structural array and the second layer of colloidal quantum dots to be formed by the second structural array silicon pillar template is fixed. The top of the second structural array silicon pillar template, the second semiconductor material precursor solution, and the first structural array form the secondary capillary liquid bridge; The second semiconductor material precursor solution is a CdSe / ZnS quantum dot precursor solution, and the solvent of the second semiconductor material precursor solution is toluene or chlorobenzene; When the first semiconductor material precursor solution is a blue light quantum dot precursor solution, the second semiconductor material precursor solution is a red light quantum dot precursor solution; when the first semiconductor material precursor solution is a red light quantum dot precursor solution, the second semiconductor material precursor solution is a green light quantum dot precursor solution; After dewetting, a patterned stacked heterostructure array is obtained.

2. A method for patterning and preparing a stacked heterostructure array according to claim 1, characterized in that: It further includes the following steps: S4. Perform ligand exchange again, repeat n times to prepare a patterned stacked heterostructure array, and the patterning and preparation of the stacked heterostructure array is completed. The stacked heterostructure array includes n + 2 layer structural arrays, n > 0.

3. A method for patterning and preparing a stacked heterostructure array according to claim 1, characterized in that: In step S1, the primary capillary liquid bridge is a micron-scale capillary bridge with a height of 500 - 1000 nm, and the first semiconductor material precursor solution is a single-component colloidal quantum dot solution; The first structural array silicon pillar template is processed by photolithography and etching, and the first structural array silicon pillar template is modified with FAS.

4. A method for patterning and preparing a stacked heterostructure array according to claim 1, characterized in that: When using the soaking method, the second ligand solution is a 5% mass fraction mercaptopropionic acid / methanol solution; when using the spin coating method, the second ligand solution is a 5% mass fraction mercaptopropionic acid / methanol solution with a volume of 10 μL.

5. A method for patterning and preparing a stacked heterostructure array according to claim 1, characterized in that: In step S3, the second structural array silicon pillar template is processed by photolithography and etching, and the second structural array silicon pillar template is modified with FAS.

6. A method for patterning and preparing a stacked heterostructure array according to claim 2, characterized in that: In step S3, the second structural array silicon pillar template can be the same as the first structural array silicon pillar template; The ligand exchange in step S4 refers to the mutual exchange between the first ligand and the second ligand.

7. A method for patterning and preparing a stacked heterostructure array according to claim 3, characterized in that: In step S1, the substrate is any one of the following: silicon wafer, silicon dioxide wafer, quartz wafer, glass wafer, and indium tin oxide conductive glass. Before preparation, the substrate is washed clean and dried with nitrogen.

8. A method for patterning and preparing a stacked heterostructure array according to claim 1, characterized in that: In steps S1 and S3, the shapes of the first structural array silicon pillar template and the second structural array silicon pillar template are both any one of the following: linear array, curved array, circular array, square array, and triangular array.

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