Quantum dot-based light-emitting micro-device and transient emulsion method for preparing the same

Abstract

The application belongs to the technical field of LED, and particularly discloses a quantum dot-based light-emitting micro device and a transient emulsion method sequence preparation method thereof. The application is based on a typical transient emulsion system of n-butanol-water, constructs a transient emulsion assembly sequence printing technology, controls the hydrophilic and hydrophobic of the micro-pore inside and outside of a template, utilizes the intrinsic advantage of easy limited emulsification of the transient emulsion method, and designs a printing process of the layer-by-layer assembly sequence device of the micro-pore inside layer. The light-emitting micro device with the conductive hydrophilic material (ITO) as the positive electrode, the PEDOT:PSS solution conductive polymer as the hole transport layer, the water-soluble CdSe quantum dot as the self-luminous building block, the zinc oxide nanoparticles as the electron transport layer, and the Ag electrode as the negative electrode is prepared, and the quantum dot-based self-luminous material micro chip is realized. The application can realize controllable preparation of a large area, does not need expensive equipment, and saves the cost. In addition, the application can realize rapid preparation, and provides an implementation scheme and an optimal process for low-cost, high-efficiency and controllable construction of the next generation of Micro-QLED display.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum dot light-emitting devices, in particular to a quantum dot-based light-emitting micro-device and a transient emulsion method for preparing the same. BACKGROUND

[0002] The current display industry has entered a hot stage of "upgrading", and various display technology innovations have emerged. For example, the constantly improved backlight liquid crystal display (LCD), organic self-luminous diode (OLED) display, quantum dot self-luminous diode (QLED) display, micro semiconductor self-luminous Micro-LED display and laser LD display, etc., showing a multi-legged commercial pattern.

[0003] For Micro-QLED, the new process requirement is to improve the performance of the device on the basis of realizing high resolution of the device. Generally speaking, the quantum dots in QLED cannot be used by the traditional evaporation process because they are easily affected by temperature and humidity. Relatively mild spin coating, dip coating, brushing and other extensive processes are usually used. To achieve precise quantification of the pixel points, inkjet printing is needed. Compared with spin coating, inkjet printing technology reduces material waste and can achieve patterning and full-color printing, which is suitable for preparing large-area devices. However, the ink droplet size in inkjet printing is usually in the order of hundreds of microns, which cannot realize high-resolution pattern printing. And due to the coffee ring effect, it is difficult to obtain a uniform and dense quantum dot film. Therefore, inkjet printing cannot meet the new process requirements of Micro-QLED. In addition, for the existing inkjet printing, transfer printing, photolithography and other quantum dot micro-device preparation processes, most of these processes are the patterning or miniaturization of the quantum dot light-emitting layer, and the remaining functional layers are adopted by spin coating. In such a process, the hole transport layer and the electron transport layer are in direct contact, resulting in serious leakage current phenomenon, which in turn affects the light-emitting efficiency of the device. Therefore, a new process is needed to improve this phenomenon. SUMMARY

[0004] In view of the above deficiencies in the prior art, the present application provides a transient emulsion method for preparing a quantum dot-based light-emitting micro-device. That is, by using the confinement effect of the hole template and the transient emulsion method, the large-area, precise quantification and positioning assembly sequence of the nano-structure building block in the hole are realized.

[0005] To achieve the above object, the present application adopts the following technical scheme: a transient emulsion method for preparing a quantum dot-based light-emitting micro-device, comprising the following steps:

[0006] Step A, take a template with a micro-pore array, the pore wall of which is hydrophobic material, the bottom of which is conductive hydrophilic material, drop n-butanol on the face where the array pores open until the array pores are completely filled, after the array pores are fully infiltrated, remove the excess n-butanol outside the array pores;

[0007] Step B, drop PEDOT:PSS solution on the face where the array pores open, stand for a period of time, and fill the array pores with n-butanol and PEDOT:PSS solution;

[0008] Step C, remove the excess n-butanol and PEDOT:PSS solution outside the array pores, and then stand to dry, forming a discontinuous PEDOT:PSS film layer in the array pores;

[0009] Step D, drop n-butanol into the array pores where the PEDOT:PSS film layer is formed, and after the array pores are fully infiltrated, remove the excess n-butanol outside the array pores;

[0010] Step E, drop CdSe / ZnS aqueous quantum dots into the n-butanol in the array pores, and after the CdSe / ZnS aqueous quantum dots and n-butanol are fully infiltrated, fill the array pores;

[0011] Step F, remove the excess n-butanol and CdSe / ZnS aqueous quantum dot solution, and then stand to dry, forming a discontinuous aqueous quantum dot film layer on the surface where the PEDOT:PSS film layer is located in the array pores;

[0012] Step G, drop ZnO ethanol solution on the face where the array pores open, spin-coat and dry to form a continuous ZnO layer;

[0013] Step H, use a vacuum evaporation instrument to vacuum evaporate Ag electrode on the surface of the ZnO layer, and then package to obtain a quantum dot-based light-emitting micro device.

[0014] Further improvement of the transient emulsion method for preparing quantum dot-based light-emitting micro devices:

[0015] Preferably, before dropping n-butanol on the face where the array pores open in step A, the template is first placed in an oxygen plasma cleaning machine for 60-300s.

[0016] Preferably, the shape of the micro-pores on the template in step A is one of square, circular, triangular, and rhombus; the opening area of a single pore is 0.25μm 2 -6400μm 2 , the diameter is 500nm-80μm, the nearest distance of the pores is 5μm-80μm, and the depth of the pores is 5μm-40μm.

[0017] Preferably, the concentration of n-butanol is 90wt%-99.9wt%, and the n-butanol is dropped in steps A and D, and then the array holes are fully infiltrated in air atmosphere, and the standing time is 20s-600s.

[0018] Preferably, in step B, the concentration of PEDOT:PSS solution is 1.3-1.7wt%, and the standing time after dropping the PEDOT:PSS solution is 20s-600s; and in steps C and F, the standing and drying time is 1h-12h, and the temperature is 40℃-300℃.

[0019] Preferably, in step E, the standing time after dropping the CdSe / ZnS aqueous quantum dot solution is 20s-600s, the ligand of the CdSe / ZnS aqueous quantum dot solution is mercaptopropionic acid MPA, the wavelength is 625±10nm, and the concentration is 1nmol / mL-20nmol / mL.

[0020] Preferably, in step G, the concentration of ZnO in the ZnO ethanol solution is 20-1000mg / ml.

[0021] Preferably, in step G, the spin coating is performed on a spin coater, the rotation speed of the spin coater is set to 2000rpm-7000rpm, and the time is 30s-100s; and in step G, the drying is performed in a baking machine, the temperature of the baking machine is set to 40℃-150℃, and the baking time is 20min-50min.

[0022] Preferably, in step H, the thickness of the Ag electrode is 50nm-200nm.

[0023] The second object of the present application is to provide a quantum dot-based light-emitting micro device facing the transient emulsion method sequence preparation method.

[0024] The beneficial effects of the present application compared with the prior art are:

[0025] 1) For the existing quantum dot micro device preparation processes such as inkjet printing, transfer printing, and photolithography, most of these processes are to pattern or miniaturize the quantum dot light-emitting layer, and the remaining functional layers are adopted by spin coating. These preparation processes cause the direct contact of the hole transport layer and the electron transport layer, resulting in the leakage current phenomenon during the operation of the device, and thus affecting the performance of the device. The present application introduces each functional layer into the photoresist hole array to realize the miniaturization of the device, so that it is only assembled in the micro-holes. And the photoresist is used for isolation, which will not cause the bad contact between the devices. Therefore, the direct contact of the hole transport layer and the electron transport layer will not occur, thereby reducing the leakage current of the device and improving the performance of the device.

[0026] 2) Due to the coffee ring effect, it is difficult to obtain uniform and dense quantum dot films by inkjet printing technology. The present application takes advantage of the inherent advantage of transient emulsion system that can easily limit emulsification, and can obtain micron-level or even hundred-nanometer-level emulsion droplets in the micro-pore template. The present application selects a template composed of hydrophobic materials (such as photoresist) and conductive hydrophilic materials (ITO) with an ordered array of micro-pores with uniform size, so that the bottom of the pore is hydrophilic and the sidewall is hydrophobic. Therefore, the water phase is spread on the bottom, so that the interface is a plane. The PEDOT:PSS solution used is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate solution, which belongs to conductive polymer and can be filled in the array pore after being dissolved with n-butanol. The CdSe / ZnS aqueous phase quantum dot is a core-shell structure CdSe / ZnS aqueous phase quantum dot with a ligand of mercaptopropionic acid MPA, and the wavelength is 625±10nm. When the diameter of the quantum dot is nanometer level, the rapid assembly of microspheres can be realized, and when the diameter of the colloidal sphere is micron level, the uniform distribution of the small spheres can be realized, so that a micro-plane array is formed in the array micro-pore of the micro-pore array substrate, and the purpose of realizing the miniaturization of the structure of each functional layer is achieved.

[0027] 3) The present application utilizes a new transient emulsion system of two-phase partial mutual solubility, and provides a transient emulsion method for quantum dot-based light-emitting micro device. The so-called "transient" describes a short process of rapid diffusion and depletion of emulsion droplets in a partially miscible emulsion system. For example, the existence time of micron-sized water droplets in n-butanol phase is only seconds (proportional to the size of the droplet). Further, according to the Young-Laplace equation, such transient emulsion droplets, due to the dynamic diffusion of two phases at the interface, are in a completely miscible state, and the surface tension can be ignored. Therefore, without strong fluid shear disturbance, micron-level emulsification can be achieved, and theoretically, any small droplet size can be achieved. Compared with the hundred-micron level of inkjet printing, the present application has been greatly improved. The present application introduces the transient emulsion method into the system to prepare complete devices in the micro-pore template, which can realize the miniaturization of pixel units, thereby meeting the new requirements of micro-process for Micro-QLED.

[0028] 4) The preparation process of the technology is simple and has strong universality, and does not require precise and expensive instruments. It can greatly reduce the cost and production time of quantum dot micro devices, and greatly improve the production efficiency. It provides a good limiting effect for the subsequent structure assembly, ensures the order of the assembled structure arrangement and the uniformity of the size, and greatly weakens the randomness of the traditional self-assembly strategy.

[0029] 5) The present application is based on water-n-butanol transient emulsion system, which can not only simply regulate the thickness of the final assembled functional layer by regulating the concentration of the substance in the aqueous solution to achieve the purpose of improving the device performance, but also can realize the purpose of improving the quality of each functional layer film by regulating the hydrophilic-hydrophobic difference. In this process, only simple concentration regulation and hydrophilic-hydrophobic regulation are needed, and the process is simple and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 The optical microscope photos obtained by observing the prepared hemispherical PEDOT:PSS solution with a Zeiss microscope in Example 1 of the present application are shown in the following figures. Figure 1 In the figures, a corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 1.4wt%, Figure 1 In the figures, b corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.7wt%, Figure 1 In the figures, c corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.35wt%.

[0032] Figure 2 The pictures obtained by analyzing the prepared hemispherical functional layer PEDOT:PSS solution with an atomic force microscope (AFM) in Example 1 of the present application are shown in the following figures. Figure 2 In the figures, a corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 1.4wt%, Figure 2 In the figures, b corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.7wt%, Figure 2 In the figures, c corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.35wt%.

[0033] Figure 3 The optical microscope images obtained by observing the prepared layered PEDOT:PSS solution with a Zeiss microscope in Example 2 of the present application are shown in the following figures.

[0034] Figure 4This is a schematic diagram of the process flow for preparing quantum dot-based light-emitting microdevices using a transient emulsion sequencing process and a spin coating process in Comparative Examples 1 and 2 of the present invention.

[0035] Figure 5 The image shown is an optical microscope image obtained from the electroluminescence observation of the complete QLED device fabricated using a Zeiss microscope in Comparative Example 1 of this invention.

[0036] Figure 6 The image shown is an optical microscope image obtained from the electroluminescence observation of the complete QLED device fabricated using a Zeiss microscope in Comparative Example 2 of this invention.

[0037] Figure 7 This is a performance comparison diagram of the complete QLED devices prepared by Comparative Example 1 and Comparative Example 2 of the present invention.

[0038] in Figure 7 In the figure, 'a' corresponds to the leakage current performance of the device. Figure 7 In the figure, 'b' corresponds to the brightness performance of the device. Figure 7 In this context, 'c' corresponds to the external quantum efficiency (EQE) of the device.

[0039] Figure 8 This is a schematic diagram of the process for fabricating quantum dot-based light-emitting microdevices using a two-step transient emulsion sequencing process in Example 3. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0041] First, purchase the following materials used in this invention from the market: domestic SU8-2050 photoresist, domestic developer (general type), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS solution, model 4083, concentration 1.3-1.7wt%), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(p-butylphenyl))diphenylamine)] (TFB), CdSe / ZnS oil-phase quantum dots (solution: n-octane, concentration: 10mg / mL), CdSe / ZnS aqueous-phase quantum dots (ligand mercaptopropionic acid MPA, wavelength 625±10nm, concentration 10nmol / mL), ZnO nanoparticles (concentration 30mg / ml, solvent ethanol), n-butanol (concentration 90wt%-99.9wt%), ethanol solution, acetone solution, and chlorobenzene solution.

[0042] Example 1

[0043] The embodiment provides a preparation method of an ordered PEDOT:PSS solution layer structure array, and specifically comprises the following steps.

[0044] S1, a template with a micropore array is taken, the hole wall of the array hole in the template is a hydrophobic material (photoresist), the hole bottom is a conductive hydrophilic material (ITO), the opening shape of the hole is a square, the opening size is 40μm*40μm, the nearest distance of adjacent holes is 20μm, and the depth of the hole is 1μm;

[0045] 6μl of n-butanol is added dropwise on the surface where the array hole openings are located until the array holes are completely filled, and after the array holes are fully infiltrated in an air atmosphere, the excess n-butanol outside the array holes is removed;

[0046] S2, 5μl of PEDOT:PSS solution (concentration of 1.4wt%) is added dropwise on the surface where the array hole openings are located, and the n-butanol and the PEDOT:PSS solution are filled into the array holes after being placed in an air atmosphere for 20s;

[0047] S3, the excess n-butanol and the PEDOT:PSS solution outside the array holes are removed, and then the array is placed in an oven at 75°C for 1h for drying, and a discontinuous hemispherical PEDOT:PSS film layer is assembled in the single hole in the array hole.

[0048] Referring to the above steps, the concentration of the PEDOT:PSS solution (model 4083) in step S2 is changed to 0.7wt% and 0.35wt% respectively, and a hemispherical PEDOT:PSS film layer is assembled in the single hole in the array hole.

[0049] Figure 1 The optical microscope photos are obtained by observing the hemispherical PEDOT:PSS solution prepared in the embodiment 1 of the application by using a Zeiss microscope. Figure 1 In the figure, a corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 1.4wt%, Figure 1 In the figure, b corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.7wt%, Figure 1 In the figure, c corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.35wt%. Figure 1 It can be known that the ordered PEDOT:PSS solution hemispherical structure array is prepared through the embodiment, and the height and size of the hemispherical structure can be regulated by adjusting the concentration of the PEDOT:PSS solution.

[0050] Figure 2 The picture obtained by using atomic force microscope (AFM) to analyze the hemispherical functional layer PEDOT:PSS solution prepared in step S3 in embodiment 1 of the present application. Among them Figure 2 a corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 1.4wt%, Figure 2 b corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.7wt%, Figure 2 c corresponds to the PEDOT:PSS transient emulsion method assembly result when the concentration of the PEDOT:PSS solution is 0.35wt%. From Figure 2 It can be seen that the ordered array of PEDOT:PSS solution hemispherical structure is prepared by this embodiment, and the height and size of the hemispherical structure can be adjusted by adjusting the concentration of the PEDOT:PSS solution.

[0051] Embodiment 2

[0052] The embodiment provides a preparation method of an ordered array of PEDOT:PSS solution layered structure, and the specific steps refer to embodiment 1, and the only difference is that the template of the micropore array in step S1 is first placed in an oxygen plasma cleaning machine for treatment for 60s before 6ul of n-butanol is added. Finally, a discontinuous layered PEDOT:PSS film layer is assembled in a single hole in the array hole.

[0053] Figure 3 The optical microscope image obtained by using Zeiss microscope to observe the layered PEDOT:PSS solution prepared in embodiment 2 of the present application, so as to obtain the optical microscope image. As Figure 3 shown, the ordered array of layered PEDOT:PSS solution structure array is prepared in the above embodiment.

[0054] Comparative example 1

[0055] The embodiment provides a method for preparing a quantum dot-based light-emitting micro device by using a transient emulsion sequence process + spin coating process, and the preparation process is as shown in Figure 4 The embodiment provides a method for preparing a quantum dot-based light-emitting micro device by using a transient emulsion sequence process + spin coating process, and the preparation process is as shown in

[0056] S1, a template with a micropore array is taken, the hole wall of the array hole in the template is a hydrophobic material (photoresist), the bottom of the hole is a conductive hydrophilic material (ITO), the opening shape of the hole is a square, the opening size is 40umx40um, the nearest distance of adjacent holes is 20um, and the depth of the hole is 1um;

[0057] Dropping 6 μl of n-butanol on the surface where the array hole openings are located until the array hole is completely filled, and after the array hole is fully infiltrated, removing the excess n-butanol outside the array hole;

[0058] S2, dropping 5 μl of PEDOT:PSS solution (model 4083) (concentration of 1.4wt%) on the surface where the array hole openings are located, and standing for 20s in the air atmosphere, and the two solutions are mixed to fill the array hole;

[0059] S3, removing the excess n-butanol and PEDOT:PSS solution outside the array hole, and then placing it in an oven at 75℃ for 1h to dry, and assembling a single hole in the array hole to form a discontinuous hemispherical PEDOT:PSS film layer (as a hole injection layer);

[0060] S4, configuring a TFB solution (concentration of 7mg / mL, chlorobenzene solution); placing the template assembled with the PEDOT:PSS film layer on a spin coater, and dropping the TFB solution into the array hole assembled with the PEDOT:PSS film layer, setting the rotation speed to 3000rpm and the spin coating time to 40s; and then placing the template in a baking machine, setting the temperature to 120℃ and the time to 20min, to dry to obtain a continuous TFB layer (as a hole transport layer);

[0061] S5, placing the template with the prepared TFB layer on a spin coater, and dropping the oil phase quantum dot solution onto the TFB layer, setting the rotation speed to 2000rpm and the spin coating time to 30s; and then placing the template in a baking machine, setting the temperature to 80℃ and the time to 20min, to dry to obtain a continuous oil phase quantum dot layer (as a quantum dot light emitting layer);

[0062] S6, placing the template with the prepared oil phase quantum dot layer on a spin coater, and dropping the ZnO ethanol solution (concentration of ZnO is 3mg / ml) onto the oil phase quantum dot layer, setting the rotation speed to 2000rpm and the spin coating time to 30s; and then placing the template in a baking machine, setting the temperature to 80℃ and the time to 20min, to dry to obtain a continuous ZnO layer (as an electron injection layer);

[0063] S7, using a vacuum evaporation instrument to vacuum evaporate Ag electrode on the surface of the ZnO layer with a thickness of 100nm, and then packaging to obtain a complete QLED device.

[0064] Comparative Example 2

[0065] The embodiment provides a method for preparing a quantum dot-based light-emitting micro device by using a transient emulsion sequence process + spin coating process, and the preparation process is as shown in Figure 4The shown, specific steps refer to Comparative Example 1, the only difference is that the template of the microwell array in step S1 is placed in the oxygen plasma cleaning machine for 60s before 6μl of n-butanol is added. Step S3 assembles a layered PEDOT:PSS film layer in a single well in the array well. The complete QLED device is finally prepared.

[0066] Figure 4 The flowchart of the transient emulsion method sequence preparation method for quantum dot-based light-emitting micro devices in Comparative Examples 1 and 2 of the present application is shown. The specific process is described as follows: the first step is to use n-butanol to infiltrate the template; the second step is to add PEDOT:PSS solution to make it enter the well, and to realize assembly within ns level time, and after drying, a PEDOT:PSS film layer (as a hole injection layer) is assembled in the array well; then the spin coating of the hole transport layer, quantum dot light-emitting layer, and electron injection layer is sequentially performed, and finally the Ag electrode is plated to prepare the complete QLED device.

[0067] Figure 5 The electroluminescence microscopic image of the complete QLED device prepared in Comparative Example 1 of the present application is shown. Figure 6 The electroluminescence microscopic image of the complete QLED device prepared in Comparative Example 2 of the present application is shown. Figure 5 It can be seen that when a hemispherical PEDOT:PSS film layer is assembled in a single well in the array well, it is not conducive to uniform light emission of the device, which can cause the center of the device to be unable to light up. Figure 6 It can be seen that when a layered PEDOT:PSS film layer is assembled in a single well in the array well, uniform light emission of the device can be achieved, and the brightness of the device is also significantly improved.

[0068] Figure 7 The performance comparison chart of the complete QLED devices prepared in Comparative Example 1 and Comparative Example 2 of the present application is shown. The device is placed in the test platform, and the current meter is turned on for measurement, and the performance data can be obtained. Among them Figure 7 In a, the leakage current performance of the device corresponds to, Figure 7 In b, the brightness performance of the device corresponds to, Figure 7 In c, the external quantum efficiency (EQE) of the device corresponds to Figure 7 It can be seen that compared with the hemispherical structure of PEDOT in Comparative Example 1, the layered structure of PEDOT:PSS solution in Comparative Example 2 can obtain better performance, such as a significant decrease in leakage current and an increase in brightness.

[0069] Example 3

[0070] The present embodiment provides a method for preparing a quantum dot-based light-emitting micro device by two transient emulsion sequence processes, and the preparation flowchart is shown as Figure 8 The method comprises the following steps:

[0071] S1, take a template with a micro-hole array, the hole wall of the array hole in the template is a hydrophobic material (photoresist), the hole bottom is a conductive hydrophilic material (ITO), the opening shape of the hole is a square, the opening size is 40 μm x 40 μm, the nearest distance of adjacent holes is 20 μm, and the depth of the hole is 1 μm;

[0072] Drop 6 μl of n-butanol on the surface where the array hole openings are located until the array holes are completely filled. After the array holes are fully immersed in the air atmosphere, remove the excess n-butanol outside the array holes;

[0073] S2, drop 5 μl of PEDOT:PSS solution (type 4083) (concentration 1.4 wt%) on the surface where the array hole openings are located, and stand in the air atmosphere for 20 s. The two solutions are mixed to fill the array holes;

[0074] S3, remove the excess n-butanol and PEDOT:PSS solution outside the array holes, and then place them in an oven at 75°C for 1 h to dry. An discontinuous PEDOT:PSS film layer (as a hole injection layer) is assembled in the array holes;

[0075] S4, drop n-butanol into the array holes where the PEDOT:PSS film layer is formed. After the array holes are fully immersed in the air atmosphere, remove the excess n-butanol outside the array holes;

[0076] S5, drop 5 μl of CdSe / ZnS aqueous quantum dots (concentration: 10 nmol / ml, solvent: deionized water, luminescence wavelength: 625 nm, ligand: MPA) into the n-butanol in the array holes, and stand in the air atmosphere for 20 s. The two solutions are mixed to fill the inside of the array holes;

[0077] S6, remove the excess n-butanol and CdSe / ZnS aqueous quantum dots, and then place them in an oven at 75°C for 0.5 h to dry. A discontinuous aqueous quantum dot film layer (as a quantum dot light-emitting layer) is assembled on the surface where the PEDOT:PSS film layer is located in the array holes;

[0078] S7, place the template with the aqueous quantum dot layer prepared into a spin coater, drop ZnO ethanol solution (ZnO concentration 3 mg / ml) onto the oil quantum dot layer, set the rotation speed to 2000 rpm, and spin for 30 s. Then place the template in a glue baking machine at a temperature of 80°C for 20 min to dry to form a continuous ZnO layer (as an electron injection layer);

[0079] S8, use a vacuum evaporation instrument to vacuum evaporate Ag electrode on the surface of the ZnO layer with a thickness of 100 nm, and then package to obtain a quantum dot-based light-emitting micro device facing the quantum dot.

[0080] Example 4

[0081] The embodiment provides a method for preparing a quantum dot-based light-emitting micro device through twice transient emulsion process, and a preparation flow is shown in Figure 8 The embodiment provides a method for preparing a quantum dot-based light-emitting micro device through twice transient emulsion process, and a preparation flow is shown in

[0082] The electroluminescence microscopic images of the quantum dot-based light-emitting micro devices prepared in the embodiment 3 and the embodiment 4 are collected, and the light-emitting performance of the devices is tested. The test result proves that the confined effect of the hole template and the transient emulsion method are used to realize large-area, accurate quantification and positioning assembly and sequence of the nano-structure base units in the hole through twice transient emulsion process. The quantum dot-based light-emitting micro device prepared by the application does not have the phenomenon that the hole transport layer and the electron transport layer are directly contacted, thereby reducing the leakage current of the device and achieving the effect of improving the performance of the device, and the device has excellent light-emitting efficiency. Compared with the existing inkjet printing, the quantum dot base units are sequenced in a specific way in the embodiment, and the micron-level self-luminous pixel chip is directly constructed on the substrate, without complex micro-nano processing and mass transfer, so that the manufacturing cost is reduced.

[0083] The above describes only the preferred specific embodiments of the application, but the protection scope of the application is not limited to this. Any changes or replacements within the technical range disclosed by the application can be easily thought by those skilled in the art, and should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A transient emulsion-based ordered fabrication method for quantum dot-based light-emitting microdevices, characterized in that, The method comprises the following steps: Step A, a template with a micropore array is taken, the pore wall of the array hole in the template is a hydrophobic material, the bottom of the hole is a conductive hydrophilic material, n-butanol is added to the face where the array hole is opened until the array hole is completely filled, after the array hole is fully immersed, the excess n-butanol outside the array hole is removed; Step B, the PEDOT:PSS solution is added to the face where the array hole is opened, and after a period of time, the n-butanol and the PEDOT:PSS solution are filled into the array hole; Step C, the excess n-butanol and the PEDOT:PSS solution outside the array hole are removed, and then dried, and a discontinuous PEDOT:PSS film layer is assembled in the array hole; Step D, n-butanol is added to the array hole where the PEDOT:PSS film layer is formed, and after the array hole is fully immersed, the excess n-butanol outside the array hole is removed; Step E, the CdSe / ZnS aqueous quantum dot solution is added to the n-butanol in the array hole, and after the CdSe / ZnS aqueous quantum dot and the n-butanol are filled into the array hole, the excess n-butanol and the CdSe / ZnS aqueous quantum dot solution are removed, and then dried, and a discontinuous aqueous quantum dot film layer is assembled on the surface of the PEDOT:PSS film layer in the array hole; Step F, the ZnO ethanol solution is added to the face where the array hole is opened, and then spin-coated and dried to form a continuous ZnO layer; Step G, a vacuum evaporation instrument is used to vacuum evaporate Ag electrode on the surface of the ZnO layer, and then packaged to obtain a quantum dot-based light-emitting micro device. Before the n-butanol is added to the face where the array hole is opened in step A, the template is first placed in an oxygen plasma cleaning machine for 60s-300s.

2. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. The concentration of the n-butanol is 90wt%-99.9wt%, and after the n-butanol is added in steps A and D, the array hole is fully immersed in the air atmosphere, and the standing time is 20s-600s.

3. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. The shape of the micropores on the template in step A is one of square, circle, triangle, and diamond; the opening area of a single hole is 0.25 μm 2 - 6400 μm 2 , the diameter is 500 nm-80 μm, the nearest distance of the holes is 5 μm-80 μm, and the depth of the holes is 5 μm-40 μm.

4. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. In step B, the PEDOT:PSS solution has a type of 4083 and a concentration of 1.3-1.7wt%, and after the PEDOT:PSS solution is added, it is stood for 20s-600s; in steps C and F, the standing time for drying is 1h-12h, and the temperature is 40℃-300℃.

5. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. In step E, after the CdSe / ZnS aqueous quantum dot solution is added, it is stood for 20s-600s, the ligand of the CdSe / ZnS aqueous quantum dot solution is mercaptopropionic acid MPA, the wavelength is 625±10nm, and the concentration is 1nmol / mL-20nmol / mL.

6. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. In step G, the concentration of ZnO in the ZnO ethanol solution is 20-1000mg / ml.

7. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. In step G, the spin coating is performed on a spin coater, the rotation speed of the spin coater is set to 2000rpm-7000rpm, and the time is 30s-100s; in step G, the drying is performed in a baking machine, the temperature of the baking machine is set to 40℃-150℃, and the baking time is 20min-50min.

8. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. In step H, the thickness of the Ag electrode is 50nm-200nm.

9. The method of claim 1, wherein the method is a transient emulsion method for fabricating quantum dot-based micro light emitting devices. ​ 10. A quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method for preparing a quantum dot-based light emitting micro-device facing method

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