CN113713975B - A four-electrode electrostatic spray printing device and film preparation method - Google Patents

Abstract

The invention discloses a four-electrode electrostatic spray printing device and a film preparation method, wherein the printing device includes an active liquid supply system, an externally applied high-voltage system and a three-dimensional mobile platform, and the externally applied high-voltage system includes a high-voltage power supply and is electrically connected to the high-voltage power supply The four-electrode structure includes a fixed frame, a needle set in the middle of the fixed frame, and four electrode columns set at four ends of the fixed frame; the active liquid supply system includes a syringe connected with the needle and a syringe pump connected with the syringe . Based on the printing device, the invention regulates the shape of the fog spot through the interference of the external electric field, compresses the circular fog spot into a long fog spot, increases the droplet density per unit area, and reduces the The pores formed by the dispersion of droplets caused by Coulomb force can optimize the morphology of the film, and the photovoltaic thin film prepared by this method can effectively improve the performance of photovoltaic devices.

Description

A four-electrode electrostatic spray printing device and film preparation method

technical field

The invention relates to the technical field of optoelectronic devices, in particular to a four-electrode electrostatic spray printing device and a film preparation method.

Background technique

In order to meet the needs of industrial production, it is one of the key challenges in the field of optoelectronic devices to develop a production process suitable for the continuous preparation of large-area optoelectronic functional thin films. Among them, spraying technology, as a droplet-based non-contact method, has attracted increasing attention due to its potential to achieve conformal deposition and good compatibility with substrate curvature and roughness.

The most challenging problems faced by spray-coating methods to produce functional thin films for high-performance optoelectronic devices are the coffee ring effect and pinhead defects. For the electrostatic spray method, the droplets repel each other due to the Coulomb force under the action of an applied electric field, which leads to a large distance between the droplets deposited on the substrate, and during the process of droplet connection to form a thin film, due to the droplet evaporation The time is short, and it is difficult to wait for new droplets to fall near it, so there are many pinhead defects in the film, which is one of the main difficulties in the preparation of high-quality optoelectronic devices by the electrostatic spray method.

Therefore, the existing technology still needs to be improved and developed.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a four-electrode electrostatic spray printing device and a film preparation method, aiming to solve the problems of needle defects and coffee ring effect in the process of preparing the film by the existing electrostatic spray method.

In order to achieve the above object, the present invention adopts the following scheme:

A four-electrode electrostatic spray printing device, which includes an active liquid supply system, an external high-voltage system and a three-dimensional moving platform, the external high-voltage system includes a high-voltage power supply and a four-electrode structure electrically connected to the high-voltage power supply, the four-electrode The structure includes a fixing frame, a needle arranged in the middle of the cross-shaped fixing frame, and four electrode columns arranged at four ends of the fixing frame; the active liquid supply system includes a syringe connected with the needle, and a syringe connected with the needle. A syringe pump connected with a syringe; the three-dimensional moving platform is used to generate relative motion between the needle and the substrate on which the thin film is placed.

In the four-electrode electrostatic spray printing device, the fixing frame is a cross-shaped fixing frame.

The four-electrode electrostatic spray printing device, wherein the cross-shaped fixing frame includes a first frame and a second frame that are perpendicular to each other, and the needle head is arranged at the vertical intersection of the first frame and the second frame, so The first support is provided with two first electrodes with the vertical intersection as a symmetrical point, and the second support is provided with two second electrodes with the vertical intersection as a symmetrical point.

In the four-electrode electrostatic spray printing device, the horizontal distance between the two first electrodes and the needle is 5-30 mm; the horizontal distance between the two second electrodes and the needle is 5-30 mm.

In the four-electrode electrostatic spray printing device, the high-voltage wiring of the high-voltage power supply is connected to the two first electrodes, and the two ground wirings of the high-voltage power supply are respectively connected to the substrate and the two second electrodes.

In the four-electrode electrostatic spray printing device, the first electrode and the second electrode are both cylindrical.

The four-electrode electrostatic spray printing device, wherein the three-dimensional mobile platform includes a fixed column for fixing the syringe pump and movable in the Z-axis direction, and a fixed column located under the needle that can move in the X-axis and Y-axis directions substrate.

A method for preparing a film of a four-electrode electrostatic spray printing device, comprising the steps of:

storing the configured printing solution in a syringe, and connecting the syringe with the needle;

Set the flow rate of the syringe pump and turn on the syringe pump, and push out the printing solution in the syringe through the syringe pump;

Turn on the high-voltage power supply and increase the voltage until a long fog spot is observed under the needle;

The substrate is placed on the substrate, the moving speed of the substrate is set, and the three-dimensional moving platform is moved according to a predetermined route to complete the film printing.

In the method for preparing a thin film based on a four-electrode electrostatic spray printing device, the moving speed of the substrate is 0.01 mm/s-10 mm/s.

In the method for preparing a thin film based on a four-electrode electrostatic spray printing device, the aspect ratio of the elongated fog spot is 2:1-10:1.

Beneficial effects: Compared with the prior art, the film preparation method based on the four-electrode electrostatic spray device provided by the present invention constrains the flight trajectory of the charged droplets by applying an electric field near the needle by the externally applied high-voltage system, and the circular fog spot is formed. It is compressed into a long strip of fog, and the aspect ratio of the fog is increased from 1:1 to 8:1 or even larger. Under the fog spot with large aspect ratio, the average spacing between droplets decreases. Under the condition of the same evaporation time of droplets, the density of droplets increases greatly, which leads to an increase in the probability of fusion between droplets, thereby reducing the needle defect of the film. At the same time, by regulating the movement path of the substrate, the thickness and quality of the deposited film can be controlled, which can effectively improve the performance of optoelectronic devices compared with ordinary electrostatic spraying.

Description of drawings

FIG. 1 is a schematic structural diagram of a four-electrode electrostatic spray printing device provided by the present invention.

FIG. 2 is an enlarged schematic diagram of a four-electrode structure in the four-electrode electrostatic spray printing device of FIG. 1 .

FIG. 3 is a flow chart of a method for preparing a thin film based on a four-electrode electrostatic spray printing device of the present invention.

FIG. 4 shows the structure of the organic solar cell device prepared by the present invention and the molecular structure formula of the organic optoelectronic material used in Examples 1-3.

Figure 5 is a comparison chart of the fog spot shape and film morphology printed by ES (ordinary electrostatic spray) and QES (four-electrode electrostatic spray).

FIG. 6 is the current-voltage curve of the active layer device prepared by ES and QES on the ITO substrate in Example 1. FIG.

7 is the current-voltage curve of the active layer device prepared by ES and QES on the PET flexible substrate in Example 2. FIG.

FIG. 8 is the current-voltage curve of the device in Example 3 in which the active layer and the interface layer are simultaneously prepared with ES or QES, respectively.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Please refer to FIG. 1 and FIG. 2 , the present invention provides a four-electrode electrostatic spray printing device. As shown in the figures, it includes an active liquid supply system, an external high-voltage system and a three-dimensional moving platform. The external high-voltage system includes a high-voltage power supply and a three-dimensional moving platform. A four-electrode structure 10 electrically connected to the high-voltage power supply, the four-electrode structure 10 includes a cross-shaped fixing frame 11 , a needle 12 arranged in the middle of the cross-shaped fixing frame, and four electrodes arranged in the cross-shaped fixing frame 11 . The four electrode columns 13 at the end; the active liquid supply system includes a syringe 21 communicated with the needle 12, and a syringe pump 22 communicated with the syringe 21; the three-dimensional mobile platform includes a syringe pump 22 for fixing and can A fixed column 31 that moves in the Z-axis direction, and a base plate 32 that is positioned below the needle 12 and can move in the X-axis and Y-axis directions.

In this embodiment, as shown in FIG. 2 , the cross-shaped fixing frame 11 includes a first frame 111 and a second frame 112 that are perpendicular to each other, and the needle 12 is disposed between the first frame 111 and the second frame 112 . The vertical intersection portion 113, the first support 111 is provided with two first electrodes 131 with the vertical intersection portion 113 as the symmetrical point, and the second support 112 is provided with the vertical intersection portion 113 as the symmetrical point of the two second electrodes 132 . In this embodiment, an insertion hole 114 is further provided on the vertical intersection part 113 , and the insertion hole 114 is used to install the syringe 21 , so that the syringe 21 is communicated with the needle 12 .

In this embodiment, by turning on the high-voltage power supply, the four electrode columns arranged at the four ends of the cross-shaped fixing frame 11 generate an electric field near the needle, so as to constrain the flying trajectory of the charged droplets flowing out from the needle, The circular fog spot is compressed into a long strip, and the aspect ratio of the fog spot is increased from 1:1 to 8:1 or even larger. Under the fog spot with large aspect ratio, the average spacing between droplets decreases. Under the condition of the same evaporation time of droplets, the density of droplets increases greatly, which leads to an increase in the probability of fusion between droplets, thereby reducing the needle defect of the film. At the same time, by regulating the movement path of the substrate, the thickness and quality of the deposited film can be controlled, which can effectively improve the performance of optoelectronic devices compared with ordinary electrostatic spraying.

In some embodiments, the horizontal distance between the two first electrodes and the needle is 5-30 mm; the horizontal distance between the two second electrodes and the needle is 5-30 mm. As an example, the horizontal distance between the two first electrodes and the needle is 20 mm, and the horizontal distance between the two second electrodes and the needle is also 20 mm. As shown in FIG. 2 , the high-voltage wires of the high-voltage power source are connected to the two first electrodes, and the two ground wires of the high-voltage power source are respectively connected to the substrate and the two second electrodes. Specifically, the high-voltage wiring of the high-voltage power supply is a live wire, which is connected to the two first electrodes and connected by metal wires in advance. Therefore, when connecting the live wire, only one of the electrodes needs to be connected; the There are two ground wires for the high-voltage power supply, one is used to connect the substrate (movable three-dimensional platform), and the other is used to connect the two second electrodes; the principle of changing the aspect ratio of the fog spot: the droplets generated by the electrostatic spray are positive Electricity is attracted and collected by the substrate (grounded) under the action of the electric field, while in the four-electrode device, a pair of first electrodes connected to a positive high voltage act as a compressed electric field to constrain the flight trajectory of the droplet, while the other pair of grounded first electrodes act as a compressive electric field. The two electrodes play the role of a tensile electric field, attracting droplets, compressing laterally, and stretching vertically, so the shape of the fog spot changes from a circle to an ellipse.

In some embodiments, both the first electrode and the second electrode are cylindrical, and both the first electrode and the second electrode are metal electrodes.

In some embodiments, a method for preparing a thin film based on a four-electrode electrostatic spray printing device is also provided, as shown in FIG. 3 , comprising the steps of:

S10, storing the configured printing solution in a syringe, and connecting the syringe with the needle;

S20, setting the flow rate of the syringe pump and turning on the syringe pump, and pushing out the printing solution in the syringe through the syringe pump;

S30. Turn on the high-voltage power supply, and increase the voltage until a long-shaped fog spot is observed under the needle;

S40 , placing the substrate on the substrate, setting the moving speed of the substrate, and making the three-dimensional moving platform move according to a predetermined route to complete the film printing.

In this embodiment, an electric field is generated near the needle through the four electrode columns arranged at the four ends of the cross-shaped fixing frame, so that the flying trajectory of the charged droplets flowing out from the needle can be restrained, and the circular fog spot can be compressed into a long strip Shape fog spot, the aspect ratio of fog spot increases from 1:1 to 8:1 or even larger. Under the fog spot with large aspect ratio, the average spacing between droplets decreases. Under the condition of the same evaporation time of droplets, the density of droplets increases greatly, which leads to an increase in the probability of fusion between droplets, thereby reducing the needle defect of the film. At the same time, by regulating the movement path of the substrate, the thickness and quality of the deposited film can be controlled, which can effectively improve the performance of optoelectronic devices compared with ordinary electrostatic spraying.

In some embodiments, the moving speed of the substrate is 0.01 mm/s-10 mm/s, but not limited thereto.

In some embodiments, the aspect ratio of the long-shaped fog spot is 2:1-10:1, but not limited thereto. As an example, the aspect ratio of the long-shaped fog spot may be 2:1, 4:1, 6:1, 7:1, 8:1, 10:1, and the like.

In some embodiments, the voltage of the high-voltage power supply is 0-10 kV, but not limited thereto.

A film preparation method based on a four-electrode electrostatic spray printing device of the present invention will be further explained below through specific examples:

Example 1

Organic photoelectric thin films were prepared on cleaned ITO glass substrates. The ITO glass substrates were ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol for 15 minutes, and then dried at 80 °C for at least 1 hour. Process 1min. PEDOT:PSS was spin-coated at room temperature with a spin-coating parameter of 3000 rpm for 30 s. The substrates were then placed on a hot plate and annealed at 150°C for 15 minutes. The substrate was then placed in a glove box to spray the organic optoelectronic solution. The organic optoelectronic material solution is prepared by dissolving the electron donor material and the electron acceptor material in a mixed solvent of chloroform and chlorobenzene (volume ratio 7:3), wherein the electron donor material is PM6, and the electron acceptor material is N3 or Y6BO, The molecular formulas of the donor and acceptor materials are shown in Figure 4. The concentration of the organic optoelectronic material solution used: 2.2 mg/ml; the moving speed of the substrate is 0.2 mm/s, and the flow rate of the syringe pump is set to: 20 μL/min. In order to compare the effect of the thin films prepared by the common electrostatic spray device, two kinds of thin films were prepared by ordinary electrostatic spray (ES) and four-electrode electrostatic spray device (QES), respectively, and the optical morphology was observed with a white light interferometer (manufacturer Zeta). . As shown in Figure 5, the fog spot of ES is a circular fog spot, while the fog spot of QES is a long-striped fog spot with an aspect ratio of 8:1. The difference in the shape of the fog spot affects the average spacing between droplets and the probability of droplet fusion, which reflects that there are many pinhole defects on the ES-prepared film on the optical topography, while the QES-prepared film has no defects due to the high droplet density. Obvious pinhole defects.

制备好的器件的有效面积(阴极和阳极重叠部分)为0.0425cm²，真空蒸镀的各层厚度是用石英晶振厚度监测仪来进行检测的。测量时是在太阳光模拟器产生的AM1.5G的光照下(100mW/cm²)进行的。电流密度-电压曲线是用Keithley2400进行测量的。器件未进行封装，所有测试均在手套箱内完成的，器件性能测试结果如表1和图6所示。器件性能测试完毕后，对不同器件的外量子效率(EQE)进行测试。After the spray preparation of the organic optoelectronic thin film was completed, the substrate was placed on a hot plate at 100 °C for 10 minutes before annealing. After the pre-annealing, the PDINO solution was spin-coated on the organic optoelectronic thin film with a concentration of 1 mg/ml and a spin coating parameter of 3000 rpm for 30 s. . Then it was transferred to a vacuum evaporation apparatus to evaporate Ag electrodes. During evaporation, the vacuum degree was 6×10 ^-4 Pa, the Ag purity was 99.99%, and the evaporation rate was 99.99%.

The effective area of the prepared device (the overlapping part of the cathode and the anode) was 0.0425 cm ² , and the thickness of each layer of vacuum evaporation was detected by a quartz crystal thickness monitor. The measurement was performed under the illumination of AM1.5G (100 mW/cm ² ) generated by a solar simulator. Current density-voltage curves were measured with a Keithley 2400. The device was not packaged, and all tests were completed in a glove box. The device performance test results are shown in Table 1 and Figure 6. After the device performance test is completed, the external quantum efficiency (EQE) of different devices is tested.

The above device structure is glass substrate/ITO/PEDOT:PSS(40nm)/PM6:N3(120nm)/PDINO(10nm)/Ag(100nm).

This example compares the performance difference between the PM6:N3 organic photovoltaic cells prepared by the present invention and a common electrostatic spray device in the same structural device. Compared with the thin film prepared by ES, the thin film prepared by QES is more dense and uniform, and the organic photovoltaic cell prepared on this basis has higher photoelectric conversion efficiency. It can be seen from the device performance table that the short-circuit current density and filling of the QES-prepared devices have significantly improved. The improvement of short-circuit current density is attributed to the reduction of pinhole defects and the reduction of exciton recombination, and the improvement of filling factor is due to Charge transport is improved at higher interfacial contacts.

Table 1. Device performance parameters of PM6:N3 organic solar cells fabricated by ES and QES on ITO substrates

Example 2

制备好的器件的有效面积(阴极和阳极重叠部分)为0.0425cm²，真空蒸镀的各层厚度是用石英晶振厚度监测仪来进行检测的。测量时是在太阳光模拟器产生的AM1.5G的光照下(100mW/cm²)进行的。电流密度-电压曲线是用Keithley2400进行测量的。器件未进行封装，所有测试均在手套箱内完成的，器件性能测试结果如表2和图7所示。Organic optoelectronic films were prepared on the cleaned flexible substrate PET. The PET substrate was ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol for 15 minutes in turn, then dried at 80 °C for at least 1 hour, and then plasma treated for 1 minute. The PH1000 was spin-coated at room temperature with a spin-coating parameter of 2000 rpm for 30 s. The substrates were then placed on a hot plate and annealed at 80°C for 15 minutes. PEDOT:PSS was subsequently spin-coated on PH1000 with spin-coating parameters of 3000 rpm for 30 s. The substrates were then placed on a hot plate and annealed at 100°C for 15 minutes. The substrate was then placed in a glove box to spray the organic optoelectronic solution. The organic optoelectronic material solution is prepared by dissolving the electron donor material and the electron acceptor material in a mixed solvent of chloroform and chlorobenzene (volume ratio 7:3), wherein the electron donor material is PM6, and the electron acceptor material is N3 or Y6BO, The molecular formulas of the donor and acceptor materials are shown in Figure 4. The concentration of the organic optoelectronic material solution used: 2.2 mg/ml; the moving speed of the substrate is 0.2 mm/s, and the flow rate of the syringe pump is set to: 20 μL/min. After the spray preparation of the organic optoelectronic thin film was completed, the substrate was placed on a hot plate at 100 °C for 10 minutes before annealing. After the pre-annealing, the PDINO solution was spin-coated on the organic optoelectronic thin film with a concentration of 1 mg/ml and a spin coating parameter of 3000 rpm for 30 s. . Then it was transferred to a vacuum evaporation apparatus to evaporate Ag electrodes. During evaporation, the vacuum degree was 6×10 ^-4 Pa, the Ag purity was 99.99%, and the evaporation rate was 99.99%.

The effective area of the prepared device (the overlapping part of the cathode and the anode) was 0.0425 cm ² , and the thickness of each layer of vacuum evaporation was detected by a quartz crystal thickness monitor. The measurement was performed under the illumination of AM1.5G (100 mW/cm ² ) generated by a solar simulator. Current density-voltage curves were measured with a Keithley 2400. The device was not packaged, and all tests were completed in a glove box. The device performance test results are shown in Table 2 and Figure 7.

The above device structure is PET/PH1000(80nm)/PEDOT:PSS(40nm)/PM6:N3(120nm)/PDINO(10nm)/Ag(100nm).

This example compares the difference in optoelectronic properties of the PM6:N3 organic optoelectronic thin film prepared by the present invention and an ordinary electrostatic spray device on a flexible substrate PET. As shown in Table 2, it can be seen from the device results that the device prepared by QES on the flexible substrate PET leads to the improvement of the short-circuit density, fill factor and photoelectric conversion efficiency of the device due to the improvement of the morphology of the active layer.

Table 2. Performance parameters of PM6:N3 organic solar electrical devices prepared by ES and QES on PET substrates

Example 3

Organic photoelectric thin films were prepared on cleaned ITO glass substrates. The ITO glass substrates were ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol for 15 minutes, and then dried at 80 °C for at least 1 hour. Process 1min. PEDOT:PSS was spin-coated at room temperature with a spin-coating parameter of 3000 rpm for 30 s. The substrates were then placed on a hot plate and annealed at 150°C for 15 minutes. The substrate was then placed in a glove box to spray the organic optoelectronic solution. The organic optoelectronic material solution is prepared by dissolving the electron donor material and the electron acceptor material in a mixed solvent of chloroform and chlorobenzene (volume ratio 7:3), wherein the electron donor material is PM6, and the electron acceptor material is N3 or Y6BO, The molecular formulas of the donor and acceptor materials are shown in Figure 4. The concentration of the organic optoelectronic material solution used: 2.2 mg/ml; the moving speed of the substrate is 0.2 mm/s, and the flow rate of the syringe pump is set to: 20 μL/min.

制备好的器件的有效面积(阴极和阳极重叠部分)为0.0425cm²，真空蒸镀的各层厚度是用石英晶振厚度监测仪来进行检测的。测量时是在太阳光模拟器产生的AM1.5G的光照下(100mW/cm²)进行的。电流密度-电压曲线是用Keithley2400进行测量的。After the spray preparation of the organic optoelectronic thin film was completed, the substrate was placed on a hot plate at 100 °C for 10 minutes before annealing. After the pre-annealing, PDINO thin films were prepared on the organic optoelectronic thin film with ES and QES devices respectively, with a concentration of 1 mg/ml and a needle tip. The distance from the substrate was 2 cm, the flow rate was 8 μL/min, and the substrate moving speed was 0.3 mm/s. Then it was transferred to a vacuum evaporation apparatus to evaporate Ag electrodes. During evaporation, the vacuum degree was 6×10 ^-4 Pa, the Ag purity was 99.99%, and the evaporation rate was 99.99%.

The effective area of the prepared device (the overlapping part of the cathode and the anode) was 0.0425 cm ² , and the thickness of each layer of vacuum evaporation was detected by a quartz crystal thickness monitor. The measurement was performed under the illumination of AM1.5G (100 mW/cm ² ) generated by a solar simulator. Current density-voltage curves were measured with a Keithley 2400.

This example compares the difference in optoelectronic properties of the organic optoelectronic thin films of the present invention and the conventional electrostatic spraying device prepared in turn on the ITO substrate for the active layer and the interface layer. As shown in Table 3 and Figure 8, it can be seen from the device results that the device with the interface layer PDINO prepared by QES also has a significant improvement in the photoelectric conversion efficiency of the device compared with the ES device.

Table 3. Performance parameters of PDINO interface layer of organic solar devices fabricated by ES and QES

The above examples can prove that the four-electrode electrostatic spray printing device in the present invention is suitable for preparing various organic optoelectronic functional thin films, and the morphology of the thin films prepared by ordinary electrostatic spray is obviously improved, thereby improving the device performance.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (9)

1. a four-electrode electrostatic spray printing device, is characterized in that, comprises active liquid supply system, external high-voltage system and three-dimensional mobile platform, and described external high-voltage system comprises high-voltage power supply and the four-electrode structure electrically connected with described high-voltage power supply, The four-electrode structure includes a cross-shaped fixing frame, a needle head arranged in the middle of the cross-shaped fixing frame, and four electrode columns arranged at four ends of the fixing frame; the active liquid supply system includes a connection with the needle head. a syringe, and a syringe pump communicated with the syringe; the three-dimensional moving platform is used to generate relative motion between the needle and the substrate on which the thin film is placed. 2 . The four-electrode electrostatic spray printing device according to claim 1 , wherein the cross-shaped fixing frame comprises a first frame and a second frame that are perpendicular to each other, and the needle is arranged on the first frame and the second frame. 3 . The vertical intersection of the two supports. The first support is provided with two first electrodes with the vertical intersection as a symmetrical point, and the second support is provided with two vertical intersections as a symmetrical point. second electrode. 3 . The four-electrode electrostatic spray printing device according to claim 2 , wherein the horizontal distance between the two first electrodes and the needle is 5-30 mm; the two second electrodes and the needle are 5-30 mm. 4 . The horizontal distance is 5-30mm. 4 . The four-electrode electrostatic spray printing device according to claim 2 , wherein the high-voltage wiring of the high-voltage power supply is connected to the two first electrodes, and the two grounding wirings of the high-voltage power supply are respectively connected to the substrate and the two electrodes. 5 . on the second electrode. 5 . The four-electrode electrostatic spray printing device according to claim 2 , wherein the first electrode and the second electrode are both cylindrical. 6 . 6 . The four-electrode electrostatic spray printing device according to claim 1 , wherein the three-dimensional moving platform comprises a fixed column for fixing the syringe pump and movable in the Z-axis direction, and a movable column located under the needle. 7 . A substrate that moves in the X-axis and Y-axis directions. 7. A method for preparing a thin film based on the four-electrode electrostatic spray printing device described in any one of claims 1-6, characterized in that, comprising the steps of: storing the configured printing solution in a syringe, and connecting the syringe with the needle; Set the flow rate of the syringe pump and turn on the syringe pump, and push out the printing solution in the syringe through the syringe pump; Turn on the high-voltage power supply and increase the voltage until a long fog spot is observed under the needle; The substrate is placed on the substrate, the moving speed of the substrate is set, and the three-dimensional moving platform is moved according to a predetermined route to complete the film printing. 8 . The method for preparing a thin film of a four-electrode electrostatic spray printing device according to claim 7 , wherein the moving speed of the substrate is 0.01 mm/s-10 mm/s. 9 . 9 . The method for preparing a thin film of a four-electrode electrostatic spray printing device according to claim 7 , wherein the length-width ratio of the elongated fog spot is 2:1-10:1. 10 .

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