JP7338917B2 - METHOD FOR CONSTRUCTING FINE STRUCTURE OF SEMICONDUCTOR NANOCRYSTAL DEVICE HAVING HIGH LIGHT EXTRACTION EFFECT - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for constructing a microstructure of a semiconductor nanocrystal device having a high light extraction effect, and more particularly to a 3D printing method for constructing a microstructure of a semiconductor nanocrystal optical device having a high light extraction effect. It belongs to the fields of imaging and photoelectric detection.

Colloidal semiconductor nanocrystals possess unique physical and chemical properties and a wealth of optical and electrical properties due to their quantum size due to size, morphology, and confinement effects. Its surface is covered with a protective layer of long-chain organic ligands, making it highly dispersible in organic solvents, while at the same time such materials possess large-area solution-processing properties. Nanocrystalline materials have been extensively studied in bioimaging, light emitting diodes, lasers and solar cells, etc., and show great potential for future applications. However, in the practical use of colloidal semiconductor nanocrystals, device processing at their macro-size has a significant impact on their optoelectronic properties. At present, semiconductor optoelectronic devices often adopt conventional manufacturing methods of forming devices of specific shapes using existing molds and jigs, but the processing is difficult and the shape and size of the formed devices are difficult. difficult to control effectively. Especially in the synthesis of optoelectronic devices with complex structures, it is difficult to achieve controllable fabrication with conventional processes. Conventional processes also greatly affect the optoelectronic properties of colloidal nanocrystals. Taking colloidal semiconductor quantum dots as an example, in the conventional process, the ligands on the surface of the quantum dots are destroyed during processing, so the quantum dots are tightly connected and even aggregated, which means that the quantum This directly leads to a significant decrease in the quantum yield and exciton lifetime of the dots. Therefore, if it is possible to manufacture an optoelectronic device with a complicated microstructure while maximizing the optoelectronic properties inherent in colloidal nanocrystals, it will be possible to efficiently utilize colloidal nanocrystals by constructing high-efficiency devices. Not only can it be realized, but it can also provide the technical basis for manufacturing devices according to specific design requirements.

The purpose of the present invention is to provide a method for constructing a microstructure of a semiconductor nanocrystal device with high light extraction effect, so as to solve the problem that the luminous efficiency of existing semiconductor nanocrystal devices cannot meet the needs of use. It is to be. This method utilizes the characteristics of 3D printing, which is difficult to achieve with conventional processing means, and constructs a specific microstructure, which is different from conventional processing means. Alleviate the problem and achieve efficient light extraction of the device, while at the same time making the semiconductor nanocrystalline device difficult to process in conventional manufacturing methods, difficult to industrially produce, and the shape of the formed device does not conform to the standard shape. It preserves the inherent advantages of 3D printing and achieves controllability of device performance, so as to address technical issues such as.

The objectives of the present invention are achieved by the following technical solutions.

A method for constructing a microstructure of a semiconductor nanocrystal device with high light extraction efficiency, comprising the following steps.

(1) The step of producing semiconductor nanocrystals, wherein the semiconductor nanocrystals in the method are monodisperse size, morphology intrinsic quantum dots, doped quantum dots, heterostructures (metal/semiconductor core-shell , heterodimer structure) nanocrystals and perovskite quantum dots, etc., which are prepared by solvothermal methods, thermal injection methods or low temperature cation exchange methods, and have surface ligands so that they can be dispersed in different solvents. can be adjusted.

(2) A step of blending a 3D printing paste, wherein the semiconductor nanocrystals are dispersed in an oil phase organic solvent such as chloroform or toluene, or an aqueous phase solvent such as water or DMF to obtain a highly dispersed semiconductor nanocrystal sol. This sol is then homogeneously mixed with an organic polymer matrix of high optical properties with certain rheological properties to obtain a 3D printing paste.

(3) The step of 3D printing the semiconductor nanocrystal device, the paste obtained by direct-writing 3D printing technology (building a 3D model, setting parameters such as spray head diameter, printing distance, printing speed, etc. ) to form a three-dimensional structure to form a semi-finished semiconductor nanocrystalline device, design various pass angles according to different requirements, and achieve control of performance at specific points and specific surfaces, Anisotropic devices can be constructed.

(4) curing and microstructuring the semiconductor nanocrystalline device, wherein the semiconductor nanocrystalline device semi-finished product is heat treated and cured to form a semiconductor nanocrystalline device with a stable microstructure; Form.

In step (1), the semiconductor nanocrystals are prepared by a liquid phase method and are coated with oleylamine, oleic acid, dodecanethiol ligands, octadecylamine, hexadecylamine, stearic acid, octanethiol, myristic acid, and tributylphosphine. , trioctylphosphine, phosphate groups, phosphate esters, intrinsic quantum dots, doped quantum dots, heterostructure nanocrystals and perovskite quantum dots. Ag-doped CdS, Cu-doped CdS, Ag-doped CdSe, Cu-doped CdSe, Ag-doped ZnS, Cu-doped ZnS, ZnS-coated CuInS ₂ , CsPbBr ₃ quantum dots produced by a liquid phase method are preferred, and their synthesis methods are conventional. You may manufacture by either method.

Specific manufacturing steps are as follows.

In step (2), formulation of the 3D printing paste includes: The produced semiconductor nanocrystals are subjected to a surface ligand treatment and dispersed in an oil phase organic solvent such as chloroform or toluene, or an aqueous phase solvent such as water or DMF to obtain a highly dispersed semiconductor nanocrystal sol. When the semiconductor nanocrystal sol is evenly mixed with 3D printing raw materials, the semiconductor nanocrystals can be well dispersed to obtain a 3D printing paste.

In particular, the concentration of semiconductor nanocrystals in the semiconductor nanocrystal sol ranges from 0.01 wt% to 99 wt%, and the mass ratio of the semiconductor nanocrystal sol to the organic polymer matrix is less than 20%.

In step (3), for the spray head diameter, the larger the spray head diameter, the easier the ejection, the thicker the printing line, the lower the printing accuracy, and the smaller the spray head diameter, the finer the ejection line, the better the printing. The surface of the object becomes smoother and the accuracy increases. The range of the spray head diameter can be 0.01-0.9 mm, and according to the actual required printing accuracy, the corresponding size of the spray head is selected.

In step (3), for the printing distance, the height from the printing spray head to the printing platform greatly affects the printing accuracy. If the printing distance is too high, the extruded line will not be completely attached to the extruded line on the printing platform, causing phenomena such as printing deviation, and if the printing distance is too low, the printed object will be pressed against the spray head. Or it may be scraped off, and the printing accuracy is similarly reduced. The distance between the printing platform and the nozzles may be 0.01-1 mm. For example, under the condition that the spray head diameter is 0.2 mm, the distance between the printing platform and the nozzle may be 0.2 mm.

In step (3), as for the printing speed, if the printing speed is too fast, the extruded printing material cannot stick to the previous printing material in a timely manner, resulting in a bridging phenomenon; The printing material curls, which affects the printing accuracy. When the printing speed is between 0.01 and 100 mm/s, for example 10 mm/s, the printed line can be uniform and keep its original shape. The printing speed v, the spray head diameter d, and the printing platform to nozzle distance h have the following relationships given by the following equations.

v = α * d + β; β = 10 * (hd) + γ (where α, β and γ are constants)
when h is greater than or equal to d, α ranges from 10 to 100 and γ ranges from −10 to 10;
When h is less than d, α ranges from 80 to 500 and γ ranges from -10 to 20.

In step (4), molding by high temperature heating according to the construction of the microstructure precursor optical device, the temperature selection range is 50 to 180 degrees Celsius, and the heating rate is 1 to 20 degrees Celsius per minute. . The high-temperature hot-molding step maintains one or more specific temperatures, and the incubation time of each step is 0.5 to 24 hours, furthermore, the construction of the microstructure of the semiconductor nanocrystalline optical device with high light extraction effect. Realize.

Beneficial Effects 1. The present invention realizes the construction of microstructures with high light extraction efficiency by 3D printing technology and heat treatment, and the front light extraction rate is about 33% compared to bulk devices cast by conventional methods. % up to about 92.3%. A significant improvement in the front light extraction effect can significantly improve the luminous efficiency of the device. Both from energy savings in device emission and from efficient utilization of colloidal quantum dots, significant beneficial effects are demonstrated.

2. The 3D printing method of the semiconductor nanocrystal optoelectronic device with controllable strength of the present invention is to fully mix the semiconductor nanocrystal solution with the organic polymer with high optical properties and perform molding by 3D printing technology to build a microstructure. By doing so, it is possible to obtain a nanocrystalline device having a high light extraction effect and also obtain an anisotropic device that is difficult to achieve with conventional techniques. The construction of microstructures can alleviate the problem of reduced light extraction efficiency due to total internal reflection of the device, greatly improve the optical properties of semiconductor nanocrystalline devices, and maintain the inherent advantages of 3D printing, making it a method of additive manufacturing. Therefore, a large amount of raw materials can be saved, only a small amount of semiconductor nanocrystals can guarantee the performance of the device, and the material is saved and the efficiency is high.

3. The present invention applies 3D printing technology to the macro-printing of semiconductor nanocrystalline materials, on the one hand, the nanocrystals can be highly dispersed in the matrix to improve the utilization efficiency of nanocrystals, and on the other hand, , the optical effects of devices can be enhanced by building microstructures, and such techniques can provide a wealth of optoelectronic applications with only a small amount of nanocrystals. Combining advanced micro-nano cross-scale manufacturing techniques such as 3D printing with semiconductor nanocrystalline materials with optoelectronic properties, we have realized the construction of three-dimensional complex microstructures by organic polymers with high optical properties, and colloidal materials. It preserves the original rich optoelectronic properties of nanocrystals to the maximum extent, and has important scientific and application value in the practical application of colloidal nanocrystal quantum dot materials.

Bulk quantum dot device fabricated by conventional casting process, a is the macro morphology of the device, b is the fluorescence test result with front emission efficiency of 33.3%. It is a device printed with PMMA as a matrix. a is the internal microstructure view of CdS:Ag nanocrystal/PMMA device under fluorescence microscope, b is the fluorescence test result of CdS:Ag nanocrystal/PMMA with front emission efficiency of 45.7%. It is a device printed with PMMA as a matrix. a is the internal microstructure view of CdS:Ag nanocrystal/PMMA device under fluorescence microscope, b is the fluorescence test result of CdS:Ag nanocrystal/PMMA with front emission efficiency of 92.3%. Macroluminescence photographs of CsPbBr ₃ QD/PC devices printed with PC as a matrix. This is a device printed using PS as a matrix. a is the internal microstructure view of _CuInS2 @ZnS nanocrystals/PS device under fluorescence microscope, b is the fluorescence test result of _CuInS2 @ZnS nanocrystals/PS with front emission efficiency of 54.6%. . It is a device printed with PS as a matrix. a is the internal microstructure view of _CuInS2 @ZnS nanocrystals/PS device under fluorescence microscope, b is the fluorescence test result of _CuInS2 @ZnS nanocrystals/PS with front emission efficiency of 81.1%. . (a) is a macro fluorescence photograph of Examples 2 and 3, and (b) is a macro fluorescence photograph of Examples 6 and 7. FIG.

In the following, the subject matter of the invention is further described with reference to specific examples, which should not be construed as a limitation to the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and unless otherwise specified, the reagents, methods and devices used in the present invention are conventional reagents in the art. , a method and apparatus.
Example 1

This example takes _CuInS2 quantum dots as an example to fabricate a semiconductor nanocrystalline device.

A method for constructing a microstructure of a semiconductor nanocrystal device with high light extraction effect, the specific steps are as follows.

Preparation of semiconductor nanocrystals First add 0.08 mol cuprous chloride and 0.008 indium acetate into the flask, add 2 mL dodecanethiol, 2 mL oleylamine, 20 mL octadecene, stir under _N2 protection, The reaction continues for 2 h when the temperature is raised to 230°C, followed by natural cooling to room temperature. Centrifuge at 8000 rpm for 20 min and disperse the precipitate obtained at the bottom in 30 mL of chloroform to obtain a _CuInS2 quantum dot solution.

Printing Paste Formulation Disperse 1 mL _of CuInS2 quantum dot solution in 10 mL of chloroform, add 5 g of PMMA powder (500 mesh) and 5 g of PS powder (800 mesh) under the condition of heating in a water bath at 50° C., and add Add 5 mL of toluene to uniformly mix the PMMA and PS with the doped quantum dots, add 10 mL of chloroform to dissolve the polylactic acid and uniformly mix with the doped quantum dots, and make the system viscous. Stir continuously until it becomes difficult to flow, stop heating and take out to obtain a 3D printing paste.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.1 mm, create a 3D model on the computer, and set parameters such as slicing, and the printing speed is 10 mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.12 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of the semi-finished product The PMMA material used in this example is placed in an oven after printing is completed, and the temperature is raised from room temperature to 60°C at a rate of 2°C/min, maintained for 12 hours, and further heated at 2°C/min. The temperature is raised to 120°C with , and the temperature is maintained for 12 hours. To obtain an optical device which is naturally cooled to room temperature and has a high light extraction effect.

Conclusion The front light transmission effect of the device reaches 48.6%, which is obviously higher than the device obtained by conventional casting process (33.3% shown in Fig. 1).
Example 2

This example uses doped quantum dots CdS:Ag as an example to fabricate a host semiconductor nanocrystal device.

A 3D printing method for semiconductor nanocrystalline optoelectronic devices with controllable intensity, the specific steps are as follows.

Preparation of semiconductor nanocrystals Firstly, a toluene sol of Ag was prepared, namely, 10 mL of oleic acid, 20 mL of oleylamine and 0.34 g of _AgNO3 were added into a flask, stirred at 50 °C for 5 min, followed by 0.06 g of Fe ( NO ₃ ) 3.4H ₂ O was added, the temperature was increased to 120°C, the temperature was gradually increased and stirred, the reaction was continued for 1 h when _the temperature was increased to 120°C, ethanol was added in a volume ratio of 1:3, Subsequently, the mixture is centrifuged at 5000 rpm for 8 minutes, and the precipitate obtained at the bottom is dispersed in 14 mL of toluene to obtain a 4 nm Ag toluene sol.

Next, a sulfur precursor solution was prepared, i.e., 10 ml of oleylamine, 20 mL of oleic acid and 128 mg of sulfur powder were placed in a flask, stirred at room temperature, and the reaction was stirred at 100° C. for 40 min, into which 30 ml of Toluene is added and uniformly stirred to obtain a sulfur precursor solution.

Ag ₂ S nanoparticle sol was prepared, i.e., 350 μL of toluene sol of monodisperse 5 nm Ag was placed in a 25 mL round-bottomed flask, into which 6 mL of toluene and 3 mL of sulfur precursor solution were added, and reacted in a water bath at 50°C. Stir the mass for 1 h, add appropriate amount of ethanol and wash by centrifugation at 6000 rpm for 10 min to obtain monodisperse Ag ₂ S nanoparticles. Disperse it in 12 ml of toluene to obtain a toluene sol of Ag ₂ S nanoparticles.

Ag-doped CdS nanocrystals were prepared, i.e., 0.2 _mL of oleic acid, 0.1 mL of oleylamine and an appropriate amount of Cd( _NO3 ) ₂ . Add 4H ₂ O methanol solution (0.1 g/ml), magnetically stir at room temperature for 3 min, add 0.1 mL of TBP, stir the reaction in a 60° C. water bath for 2 h, add ethanol and centrifuge at 5000 rpm. for 8 min to obtain CdS:Ag doped quantum dots.

Formulation of printing paste Dissolve the produced high-purity CdS:Ag-doped quantum dots in 1 mL of toluene, add 5 g of PMMA powder (500 mesh), and then add PMMA-doped quantum dots under the condition of heating in a water bath at 50°C. Add 5 mL toluene to mix evenly, and continuously stir until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain 3D printing paste.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.5 mm, create a 3D model on the computer, and set parameters such as slicing, printing speed is 15 mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.50 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of semi-finished product After printing, the semi-finished product is placed in an oven, heated from room temperature to 80°C at a rate of 2°C/min, and kept at that temperature for 24 hours. To obtain an optical device which is naturally cooled to room temperature and has a high light extraction effect.

Conclusion Fig. 2a shows a fluorescence microscope photograph of the obtained optical device, and the fluorescence test result shows that the frontal light transmission effect of the device reaches 45.7%, as shown in Fig. 2b, which is obtained by the conventional casting process. is clearly higher than the device (33.3% shown in FIG. 1).
Example 3

Based on Example 2, the control over the internal microstructure of the device is achieved by changing the technical parameters of 3D printing and the processing temperature.

Assuming that the original Example 2 printing paste formulation is maintained, proceed as follows.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.30mm, create a 3D model on the computer, and set parameters such as slicing, printing speed is 30mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.35 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of the semi-finished product After printing, the semi-finished product was placed in an oven, heated from room temperature to 50°C at a rate of 2°C/min, maintained for 8 hours, and heated to 120°C at a rate of 5°C/min for 12 hours. It is kept warm, cooled to 80° C., kept warm for 15 hours, and naturally cooled to room temperature to obtain an optical device having a high light extraction effect.

Conclusion Fig. 3a shows a fluorescence microscope photograph of the obtained optical device, and the fluorescence test result shows that the front light transmission effect of the device reaches 92.3%, as shown in Fig. 3b. significantly higher than that of the other devices (33.3% shown in FIG. 1 and 45.7% in Example 2).
Example 4

This example takes _CsPbBr3 quantum dots as an example to fabricate a semiconductor nanocrystal device.

Preparation of _CsPbBr3 Quantum Dots Weigh 0.069 g of _PbBr2 into a three-necked flask, add 5 mL of 1-octadecene, magnetically stir at room temperature for 10 min, mix evenly, and then place in a vacuum oven at 120 °C. Vacuum dry at temperature for 1 h, add 0.5 mL oleylamine, 0.5 mL oleic acid, magnetically stir for 10 min, mix evenly, then place the beaker in an oil bath and heat up to 180 ° C, PbBr ₂ After being warmed until fully dissolved, 0.4 mL of the Cs precursor solution prepared in the previous step was sucked up with a syringe and injected into the flask. It is rapidly cooled to room temperature with , washed with excess ethyl acetate, centrifuged (8000 rpm, 10 min), the precipitate is CsPbBr ₃ QDs, dispersed in 10 mL of toluene and ready for use.

Formulation of printing paste Under the condition of being heated in a water bath at 50°C, take out 3 mL of high purity _CsPbBr3 quantum dots, add 15 g of PC powder (800 mesh), further dissolve the PC and mix with the doped quantum dots evenly. Add 15 mL of toluene and stir continuously until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain 3D printing paste.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.8mm, create a 3D model on the computer, and set the parameters such as slicing, printing speed is 80mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.75 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of Semi-Finished Product The semi-finished product after printing is placed in an oven, heated from room temperature to 80° C. at a rate of 5° C./min, and kept at that temperature for 5 hours. The temperature is raised to 120°C at a rate of 5°C/min, the temperature is maintained for 12 hours, and the temperature is naturally cooled to room temperature to obtain an optical device having a high light extraction effect.

As shown in FIG. 4, the resulting optical device has obvious fluorescence transmission effect.

Conclusion The front light transmission effect of the device reaches 66.2%, which is obviously higher than the device obtained by conventional casting process (33.3% shown in Fig. 1).
Example 5

This example takes doped quantum dots CdS:Cu as an example to fabricate a semiconductor nanocrystalline device.

Preparation of semiconductor nanocrystals Copper stearate powder was first prepared, that is, 70 mL of n-hexane, 5 mmol (1.5323 g) of sodium stearate were placed in a 250 mL round-bottomed flask and stirred for 3 min, followed by 40 mL of methanol. Stirring is continued for an additional 3 min. 10 mL of 0.25 mol/L dihydrate copper chloride methanol solution is prepared and added dropwise to the above mixed solution. Finally, add 10 mL of high-purity water, stir the reaction in a water bath at 52°C for 4 h, remove the blue copper stearate in the lower layer of the flask, add an appropriate amount of methanol, wash by centrifugation at 5500 rpm for 8 min, and wash at 60°C. oven to dry and grind to powder.

Next, Cu ₂ S nanocrystals are prepared: 0.25 mmol (157.7 mg) of the above copper stearate powder, 5 mL of oleic acid, 3 mL of oleylamine are placed in a 10 mL reactor and stirred for 5 min, .25 mL of n-dodecanethiol was added to the above mixture, stirred uniformly, sealed and placed in an oven at 200°C for 2.5 h, and the brown solution was centrifuged in 1:3 ethanol at 5500 rpm for 8 min. Wash and then disperse in 8 mL of toluene.

Cu-doped CdS quantum dots were prepared: 8 mL of the above Cu ₂ S nanocrystal toluene sol and 1 mL of 0.1 g/mL Cd(NO ₃ ) _{2.4H 2} O methanol solution were placed in a 25 mL round bottom flask. and then add 0.1 mL of TBP, stir the reaction in a water bath at 56° C. for 2 h, add appropriate amount of ethanol, wash by centrifugation at 6500 rpm for 8 min, and disperse in 1 mL of toluene. get the finished product. By controlling the amount of Cd ²⁺ added and the reaction temperature in the above steps, CdS nanocrystals doped with different Cu concentrations can be synthesized.

Formulation of printing paste The high-purity CdS:Cu-doped quantum dots produced were dissolved in 1 mL of chloroform, 2.5 g of PMMA (500 mesh) was added, and polylactic acid was added, under the condition of heating in a water bath at 50 °C. Add 5 mL of chloroform to dissolve and mix with the doped quantum dots uniformly, and continuously stir until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain a 3D printing paste. .

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.12mm, create a 3D model on the computer, and set parameters such as slicing, printing speed is 8mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.1 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of Semi-Finished Product The semi-finished product after printing is placed in an oven, heated from room temperature to 80° C. at a rate of 5° C./min, and kept at that temperature for 5 hours. The temperature is raised to 120°C at a rate of 5°C/min, the temperature is maintained for 12 hours, and the temperature is naturally cooled to room temperature to obtain an optical device having a high light extraction effect.

Conclusion The frontal light transmission effect of the device reaches 62.9%, which is obviously higher than the device obtained by conventional casting process (33.3% shown in Fig. 1).
Example 6

In this example, a semiconductor nanocrystal device is manufactured using CuInS ₂ @ZnS quantum dots as an example.

A 3D printing method for semiconductor nanocrystalline optoelectronic devices with controllable intensity, the specific steps are as follows.

Preparation of semiconductor nanocrystals First, add 0.08 mol of cuprous iodide and 0.008 mol of indium acetate into the flask, add 2 mL of dodecanethiol, 2 mL of oleylamine, 20 mL of octadecene, and stir under _N2 protection. , the reaction is continued for 1 h when the temperature is raised to 230°C.

0.02 mmol of zinc acetate are dissolved in 6 mL of octadecene and 2 mL of oleic acid are added. Add the solution to the original system in 4 portions with a syringe. 15 min intervals. Allow to react 20 min after the last addition and cool naturally to room temperature. Centrifuge at 8000 rpm for 20 min and disperse the precipitate obtained at the bottom in 30 mL of toluene to obtain a CuInS ₂ @ZnS quantum dot solution.

Formulation of printing paste ₁ mL of CuInS2@ZnS quantum dot solution was dispersed in 10 mL of toluene under the condition of heating in a water bath at 25°C, and 10 g of PS powder (800 mesh) was added, and PS was mixed with the doped quantum dots. Add 10 mL of toluene to mix evenly, and stir continuously until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain 3D printing paste.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.5 mm, create a 3D model on the computer, and set parameters such as slicing, and the printing speed is 50 mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.5 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of the semi-finished product The PMMA material used in this example is placed in an oven after printing is completed, and the temperature is raised from room temperature to 60°C at a rate of 2°C/min, maintained for 12 hours, and further heated at 2°C/min. The temperature is raised to 120°C with , and the temperature is maintained for 12 hours. To obtain an optical device which is naturally cooled to room temperature and has a high light extraction effect.

Conclusion Fig. 5a shows a fluorescence microscope photograph of the obtained optical device, and the fluorescence test result shows that the front light transmission effect of the device reaches 54.6%, as shown in Fig. 5b, which is obtained by the conventional casting process. is clearly higher than the device (33.3% shown in FIG. 1).
Example 7

Based on Example 6, the control over the internal microstructure of the device is achieved by changing the technical parameters of 3D printing and the processing temperature.

Assuming that the original Example 6 printing paste formulation is maintained, proceed as follows.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.50 mm, create a 3D model on the computer, and set parameters such as slicing, and the printing speed is 50 mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.48 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of the semi-finished product The PMMA material used in this example is placed in an oven after printing is completed, and the temperature is raised from room temperature to 60°C at a rate of 2°C/min, maintained for 12 hours, and further heated at 2°C/min. The temperature is raised to 120°C with , and the temperature is maintained for 12 hours. To obtain an optical device which is naturally cooled to room temperature and has a high light extraction effect.

Conclusion Fig. 6a shows a fluorescence microscope photograph of the obtained optical device, and the fluorescence test result shows that the front light transmission effect of the device reaches 81.1%, as shown in Fig. 6b, which is obtained by the conventional casting process. 33.3% shown in FIG. 1 and 54.6% in Example 2).
Example 8

This example takes _CsPbBr3 quantum dots as an example to fabricate a semiconductor nanocrystal device.

Preparation of _CsPbBr3 Quantum Dots Weigh 0.069 g of _PbBr2 into a three-necked flask, add 5 mL of 1-octadecene, magnetically stir at room temperature for 10 min, mix evenly, and then place in a vacuum oven at 120 °C. Vacuum dry at temperature for 1 h, add 0.5 mL oleylamine, 0.5 mL oleic acid, magnetically stir for 10 min, mix evenly, then place the beaker in an oil bath and heat up to 180 ° C, PbBr ₂ After being warmed until fully dissolved, 0.4 mL of the Cs precursor solution prepared in the previous step was sucked up with a syringe and injected into the flask. was rapidly cooled to room temperature, washed with excess ethyl acetate, centrifuged (8000 rpm, 10 min), the precipitate was CsPbBr ₃ QDs, dispersed in 10 mL of toluene and ready for use.

Formulation of printing paste 3 mL of high purity _CsPbBr3 quantum dots, 15 g of PC powder (800 mesh) and 5 g of PS powder (300 mesh) were added, and further PC and PS powders were added under the condition of heating in a water bath at 50°C. Add 15 mL of toluene so as to dissolve and mix with the doped quantum dots uniformly, and continuously stir until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain a 3D printing paste. .

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.8mm, create a 3D model on the computer, and set the parameters such as slicing, printing speed is 80mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.65 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

Curing of semi-finished product After printing, the semi-finished product is placed in an oven, heated from room temperature to 100°C at a rate of 5°C/min, and maintained for 24 hours. An optical device having a high light extraction effect is obtained.

Conclusion The front light transmission effect of the device reaches 68.1%, which is obviously higher than the device obtained by conventional casting process (33.3% shown in Fig. 1).
Example 9

This example takes doped quantum dots CdS:Cu as an example to fabricate a semiconductor nanocrystalline device.

Preparation of semiconductor nanocrystals Copper stearate powder was first prepared, that is, 70 mL of n-hexane, 5 mmol (1.5323 g) of sodium stearate were placed in a 250 mL round-bottomed flask and stirred for 3 min, followed by 40 mL of methanol. Stirring is continued for an additional 3 min. 10 mL of 0.25 mol/L dihydrated copper chloride methanol solution is prepared and added dropwise to the above mixed solution. Finally, add 10 mL of high-purity water, stir the reaction in a water bath at 52°C for 4 h, remove the blue copper stearate in the lower layer of the flask, add an appropriate amount of methanol, wash by centrifugation at 5500 rpm for 8 min, and wash at 60°C. Place in an oven to dry and grind into powder.

Next, Cu ₂ S nanocrystals are prepared: 0.25 mmol (157.7 mg) of the above copper stearate powder, 5 mL of oleic acid, 3 mL of oleylamine are placed in a 10 mL reactor and stirred for 5 min, .25 mL of n-dodecanethiol was added to the above mixture, stirred evenly, sealed and placed in an oven at 200° C. for 2.5 h, and the brown solution was washed with 1:3 ethanol at 5500 rpm for 8 min by centrifugation. , followed by dispersion in 8 mL of toluene.

Cu-doped CdS quantum dots were prepared: 8 mL of the above Cu ₂ S nanocrystal toluene sol and 1 mL of 0.1 g/mL Cd(NO ₃ ) _{2.4H 2} O methanol solution were placed in a 25 mL round bottom flask. and then add 0.1 mL of TBP, stir the reaction in a water bath at 56° C. for 2 h, add appropriate amount of ethanol, wash by centrifugation at 6500 rpm for 8 min, and disperse in 1 mL of toluene. get the finished product. By controlling the amount of Cd ²⁺ added and the reaction temperature in the above steps, CdS nanocrystals doped with different Cu concentrations can be synthesized.

The prepared quantum dots are dispersed in 50 mL of n-hexane, and 0.02 mol of KI is dissolved in 40 mL of DMF. Take out 10 mL of n-hexane/quantum dot solution, put it in a 50 mL isotope bottle together with 10 mL of KI in DMF solution, stir for 4 hours, and disperse in 10 mL of DMF after centrifugation. Convert to dot and prepare for use.

Formulation of printing paste Under the condition of heating in a water bath at 50° C., take 10 mL of the prepared high-purity water-phase CdS:Cu-doped quantum dots, add 6 g of PS (800 mesh), and add PS evenly with the doped quantum dots. Add 5 mL of DMF to mix and stir continuously until the system becomes viscous, stop heating when it becomes difficult to flow, and take out to obtain 3D printing paste.

3D printing molding Put the produced paste into the barrel of the printing device, select a printing spray head with a diameter of 0.52 mm, create a 3D model on the computer, and set parameters such as slicing, printing speed is 20 mm/ s, the printing temperature is 25° C., the height of the printing platform is 0.6 mm, and 3D printing is performed to obtain semi-finished products of semiconductor nanocrystalline devices.

The semi-finished product after printing is placed in an oven, heated from room temperature to 100° C. at a rate of 5° C./min, and maintained for 12 hours. The temperature is lowered to 60° C. and kept for 12 hours. An optical device having a high light extraction effect is obtained.

The above detailed descriptions describe the objectives, technical solutions and beneficial effects of the invention in more detail. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall all fall within the protection scope of the present invention. .
conclusion

The front light transmission effect of the device reaches 57.6%, which is obviously higher than the device obtained by conventional casting process (33.3% shown in Fig. 1).

Claims (9)

Step 1 of manufacturing semiconductor nanocrystals;
In step 2 of blending the 3D printing paste, the semiconductor nanocrystals obtained in step 1 are uniformly dispersed in an oil phase organic solvent or an aqueous phase solvent to obtain a highly dispersed semiconductor nanocrystal sol, and the semiconductor nanocrystals are homogeneously mixing the crystalline sol with an organic polymer matrix of high optical properties with certain rheological properties to obtain a 3D printing paste;
a step 3 of 3D printing a semiconductor nanocrystalline device, wherein the resulting paste is subjected to three-dimensional structural molding by direct writing 3D printing technology to form a semi-finished product of the semiconductor nanocrystalline device;
Step 4 of curing and microstructuring a semiconductor nanocrystalline device, the step of heat treating said semiconductor nanocrystalline device semi-finished product to form a semiconductor nanocrystalline device with microstructures after curing; , in step 3, in the direct-writing 3D printing technology, the printing speed v, the spray head diameter d, and the distance h between the printing platform and the nozzle have the following relationship obtained by the following equation: ,
v=α*d+β;β=10*(h-d)+γ
In the formula, α, β and γ are all constants,
When h is greater than or equal to d, α is in the range 10 to 100, γ is in the range -10 to 10,
A method of fabricating a microstructure of a semiconductor nanocrystalline device , wherein α is in the range of 80-500 and γ is in the range of -10 to 20, when h is less than d . The semiconductor nanocrystals according to step 1 are prepared by solvothermal method, heat injection method or low temperature cation exchange method, and adjusting the surface ligands so that the nanocrystals can be dispersed in different solvents. The method for fabricating a microstructure of a semiconductor nanocrystalline device according to claim 1, characterized in that The semiconductor nanocrystals according to step 1 are produced by a liquid phase method and have oleylamine, oleic acid, dodecanethiol ligands, octadecylamine, hexadecylamine, stearic acid, octanethiol, myristic acid, tributylphosphine, Claim 1 characterized by intrinsic quantum dots, doped quantum dots, heterostructure nanocrystals and perovskite quantum dots having one or more of trioctylphosphine, phosphate groups, phosphate esters. 3. A method for constructing a microstructure of a semiconductor nanocrystal device according to claim 1. In step 2, the concentration of semiconductor nanocrystals in the semiconductor nanocrystal sol is 0.01 wt% to 99 wt%, and the mass ratio of the semiconductor nanocrystal sol to the organic polymer matrix is 20% or less. A method for fabricating a microstructure of a semiconductor nanocrystalline device according to claim 1. The spray head diameter range according to step 3 is 0.01-0.9 mm, and in step 3, the distance between the printing platform and the nozzle is 0.01-1 mm for the direct-write 3D printing technology. A method for constructing a microstructure of a semiconductor nanocrystal device according to claim 1, characterized in that: In step 4, the heat treatment includes multi-step heating , the temperature is 50 to 180 degrees Celsius, the temperature rising rate is 1 to 20 degrees Celsius per minute, and the heat retention time of each step is 0.5 to The method of fabricating a microstructure of a semiconductor nanocrystalline device according to claim 1, characterized in that it is 24 hours. The heterostructures of step 1 include metal/semiconductor core-shell structures and heterodimer structures;
The oil phase organic solvent contains chloroform and toluene,
the aqueous phase solvent comprises water and DMF;
The high optical property organic polymer matrix having certain rheological properties is characterized by comprising polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC) and polydiethylene glycol bisallyl carbonate (CR-39). A method for fabricating a microstructure of a semiconductor nanocrystal device according to claim 1. The method for constructing a microstructure of a semiconductor nanocrystalline device according to claim 1 , characterized in that in step 3, the printing speed is 0.01-100mm/s in the direct writing 3D printing technology. The semiconductor nanocrystals according to step 1 are Ag -doped CdS, Cu-doped CdS, Ag-doped CdSe, Cu-doped CdSe, Ag-doped ZnS, Cu-doped ZnS, ZnS-coated CuInS2, CsPbBr3 quantum dots prepared by a liquid phase method. 4. The method for constructing a microstructure of a semiconductor nanocrystal device according to claim 3 .