CN103456835B - A kind of device and method preparing solar cell gate electrode - Google Patents

Abstract

The invention provides a device and method for preparing grid electrodes of solar cells. The device includes a silver paste supply device, a nozzle height adjustment module, a nozzle, a programmable high-voltage generator, an adsorption platform, a motion platform and a control unit; The substrate is set on the adsorption platform, the first grid electrode and the second grid electrode are prepared, and the width of the second grid electrode is larger than the width of the first grid electrode; the invention uses the electrospinning direct writing process to print the solar electrode; The silver paste in the nozzle is drawn into filaments with a diameter smaller than that of the nozzle. The width and height of the printed raster lines can be controlled by controlling different voltages, nozzle heights, and substrate feed speeds. The voltage affects the stability of the Taylor cone at a certain height. The height mainly affects the height of the printed grid lines by affecting the solidification degree of the grid lines in the air. The higher the height, the higher the height of the printed grid lines. The feeding speed of the substrate mainly affects the width of the printed raster lines, the higher the speed, the thinner the raster lines.

Description

A kind of device and method for preparing grid electrode of solar cell

technical field

The invention belongs to the field of solar cells, and more specifically relates to a device and method for preparing solar cell grid electrodes.

Background technique

A solar cell is a device that directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. With the continuous progress of the photovoltaic industry, the market has put forward higher requirements for photovoltaic products. High efficiency and low cost have become important goals for the development of solar cells. One of the key steps in the production of solar cells is to fabricate very fine circuits on the front and back sides of the silicon wafers to direct the photo-generated electrons out of the cell. At the same time, in order to obtain a high-efficiency solar cell, the shading area of the grid line must be reduced, and at the same time, it must have an efficient charge collection capability, so the preparation of the front grid electrode of the solar cell is particularly important.

At present, the preparation of solar cell grid wire electrodes generally adopts a screen printing process. A general screen printing machine has: a printing stage, a printing mask, and a squeegee; The object to be printed; the printing mask is used to form a prescribed electrode pattern on the object to be printed supported and fixed on the printing stage; the squeegee is used to apply a predetermined pressure to the conductive paste arranged on the printing mask, to The printed matter is printed.

The width of the grid line prepared by the traditional process is usually more than 80 microns, and the height is 5-30 microns. The wide grid line has a large shading area, which affects light absorption; but the grid line becomes thinner, and the ohmic contact resistance of the battery becomes larger, which limits the current. The collection ability of the solar cell reduces the conversion efficiency of the solar cell. Therefore, in order to obtain a high-efficiency battery, it is necessary to reduce the width of the grid lines and increase the aspect ratio of the grid lines. The traditional screen printing process has been difficult to do. In addition, the screen printing process also has the disadvantages of wasting silver paste, expensive process equipment, wear and tear of the screen, broken grids and virtual printing, and inability to numerical control. It also increases the cost of solar cells to a certain extent. In addition, the instability of the screen printing process itself, such as the degradation of the tension of the screen due to continuous pressure during use, and the pressure of the screen may also cause damage to the cell, as well as the increase in the width of the grid line. The overall distribution of cell efficiency has a great impact, causing a certain reduction in overall efficiency.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a device for preparing solar cell grid electrodes, the purpose of which is to improve the conversion efficiency of solar cells, thus solving the problem caused by light absorption in the preparation process of existing solar cell grid lines. The technical problem of low conversion efficiency of solar cells caused by low efficiency.

The invention provides a device for preparing grid electrodes of solar cells, comprising a silver paste supply device, a nozzle height adjustment module, a nozzle, a programmable high-voltage generator, an adsorption platform, a motion platform and a control unit; the nozzle includes a printing end, Silver paste supply interface and electrical interface; the input control end of the silver paste supply device is connected with the control unit, the output control end of the silver paste supply device is connected with the silver paste supply interface of the nozzle, and the silver paste supply device is used for Under the control of the control unit, provide silver paste for the nozzle and provide the required back pressure for electrospinning; one end of the nozzle height adjustment module is connected to the control unit, and the other end of the nozzle height adjustment module is connected to the nozzle, and the nozzle height adjustment The module is used to adjust the height between the jet printing end of the nozzle and the solar substrate under the control of the control unit; the positive output end of the high voltage generator is connected to the electrical interface of the nozzle, and the high voltage generates The output negative terminal of the device is connected to the adsorption platform, the input control terminal of the high-pressure generator is connected to the control unit, and the high-pressure generator is used to, under the control of the control unit, adsorb on the nozzle and the adsorption platform. A voltage is applied between the substrates on the platform to form a high-voltage electric field, so that the silver paste forms a Taylor cone at the printing end of the nozzle, and the wire is further pulled out under the action of the high-voltage electric field; the control end of the moving platform is connected to the A control unit, the adsorption platform is set on the movement platform, and the movement platform is used to drive the substrate adsorbed on the adsorption platform to move linearly under the control of the control unit, so as to complete the printing of the grid electrode pattern.

Furthermore, the nozzle is a single nozzle or a plurality of nozzles arranged in an array.

Furthermore, it also includes: an insulating layer arranged between the adsorption platform and the solar substrate.

Furthermore, it also includes: a roll-to-roll device arranged above the adsorption platform.

The present invention also provides a method for preparing solar cell grid electrodes, comprising the steps of:

(1) Set the solar substrate on the adsorption platform;

(2) Preparation of the first gate electrode

(2.1) A nozzle with a diameter of 100-400 microns is arranged on the nozzle height adjustment module, and the electrical interface of the nozzle is connected with the high-voltage generator, and the silver paste supply interface of the nozzle is connected with the silver paste supply device, The printing end of the nozzle is perpendicular to the solar substrate;

(2.2) The control unit outputs the first control signal to control the silver paste supply device to inject silver paste into the cavity of the nozzle;

(2.3) The control unit outputs the second control signal to control the slider in the nozzle height adjustment module to slide along the screw rod to adjust the height of the nozzle array to 0.5-2cm;

(2.4) The control unit outputs the third control signal to control the high-voltage generator to apply a voltage between the nozzle and the adsorption platform; the voltage is set to 0.8-2kv;

(2.5) The control unit outputs the fourth control signal to control the motion platform to move along the X direction at a speed of 150-300mm/s, and form the first grid electrode;

(3) Prepare a second gate electrode according to the step of preparing the first gate electrode, the width of the second gate electrode is greater than the width of the first gate electrode.

Furthermore, the step (3) of preparing the second gate electrode specifically includes:

(3.1) A nozzle with a diameter of 500-1000 microns is arranged on the nozzle height adjustment module, and the electrical interface of the nozzle is connected with the high-voltage generator, and the silver paste supply interface of the nozzle is connected with the silver paste supply device, The printing end of the nozzle is perpendicular to the solar substrate;

(3.2) the control unit outputs the first control signal to control the silver paste supply device to inject silver paste into the cavity of the nozzle;

(3.3) The control unit outputs the second control signal to control the slider in the nozzle height adjustment module to slide along the screw rod to adjust the height of the nozzle array to 0.5-1 cm;

(3.4) The control unit outputs a third control signal to control the high-voltage generator to apply a voltage between the nozzle and the adsorption platform; the voltage is set to 0.8-2kv.

(3.5) The control unit outputs a fourth control signal to control the motion platform to move along the Y direction at a speed of 80-200 mm/s, and form the second grid electrode.

Furthermore, the width of the first gate electrode is 5 μm˜50 μm, and the height of the first gate electrode is 0.8 μm˜30 μm.

Furthermore, the distance between the two first gate electrodes is smaller than the distance between the two second gate electrodes.

The present invention also provides a solar grid electrode structure prepared by the above method.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can control the printing of solar electrodes by controlling different voltages, nozzle heights, and substrate feed speeds due to the use of electrospinning direct writing technology to print solar electrodes. The width and height of the gate line can be obtained, and the gate width can reach micron or even sub-micron level, and it has a higher aspect ratio. Among them, the voltage affects the stability of the Taylor cone at a certain height. The height mainly affects the height of the printed grid lines by affecting the solidification degree of the grid lines in the air. Under the condition that other conditions remain unchanged, the higher the height, the higher the height of the printed grid lines. The feeding speed of the substrate mainly affects the width of the printed raster lines. Under the condition that other conditions remain unchanged, the greater the speed, the thinner the raster lines.

Description of drawings

FIG. 1 is a schematic diagram of a graphic structure of a grid electrode of a solar cell;

2 is a schematic structural view of the device for preparing solar cell grid electrodes provided by the first embodiment of the present invention;

Fig. 3 is a layout diagram of a nozzle array in a device for preparing solar cell grid electrodes provided by an embodiment of the present invention;

Fig. 4 is a schematic structural view of a device for preparing solar cell grid electrodes provided by the second embodiment of the present invention;

Figure 5 shows the changes in the spacing of the printed grid lines caused by the number of columns of different nozzle arrays when the substrate feed speed is 200mm/s, the nozzle height is 15mm, and the voltage is 1.5kv; Figure 5(a) is the grid line printed by a single row of nozzles The line spacing is 4mm, and Figure 5(b) shows that the grid line spacing printed by two rows of nozzles is 2mm;

Figure 6 shows that when the nozzle diameter is 150 μm, the feed speed of the substrate is 200 mm/s, and the voltage is 1.5 kv, the height of the printed grid lines is different for different nozzle heights; Figure 6 (a) the height of the nozzle is 8 mm, and the height of the printed grid lines is 15μm; Fig. 6(b) the nozzle height is 15mm, and the grid line height is 20μm;

Figure 7 shows that when the nozzle diameter is 150μm and the voltage is 1.5kv, the nozzle height is 15mm, and the width of the printed grid lines is different for different substrate feed speeds; Figure 7(a) speed is 150mm/s, and the printed grid line width is 48μm ; Fig. 7 (b) speed is 300mm/s, and its grid line width is 30μm;

Figure 8 shows that when the feed speed of the substrate is 200mm/s and the voltage is 1.5kv, the height of the nozzle is 15mm, and the width of the printed grid lines is different for different nozzle diameters; in Figure 8(a), the diameter of the nozzle is 400μm, and the width of the printed grid lines is 100μm; Fig. 8(b) The diameter of the nozzle is 100μm, and the grid line width is 30μm.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Fig. 1 is a graph of solar cell grid electrodes, where a is the first grid electrode and b is the second grid electrode. In order to improve the conversion efficiency of the battery, the obtained gate electrode should not only reduce the light-shielding area, but also reduce the series resistance of the battery. Reducing the shading area requires the gate electrode width to be as small as possible, and reducing the series resistance of the battery requires the gate electrode cross section to be as large as possible. The traditional preparation method adopts the screen printing process. As mentioned above, this process cannot guarantee the aspect ratio when the width of the printed grid electrode is small. The width of the grid electrode is usually more than 80 microns, and the height is 5-30 microns. The embodiment of the present invention combines the principle of electrohydrodynamic jet printing and adopts the method of electrospinning and directly writing the grid line electrode, so as to obtain a thinner grid electrode with a larger aspect ratio. In the embodiment of the present invention, the width of the first gate electrode is 5-50 μm, and the height is 0.8-30 μm. When the width of the first gate electrode is several microns, light can be diffracted, thereby reducing the shadow area and improving conversion efficiency.

Fig. 2 is a structural schematic diagram of a device for preparing solar cell grid electrodes provided by an embodiment of the present invention, including: a silver paste supply device 1, a nozzle height adjustment module 2, a nozzle 3, a programmable high-voltage generator 4, an adsorption platform 5, and a moving Platform 6, solar substrate 7, control unit 8. The silver paste supply device 1 supplies silver paste to the nozzle 3 and provides the back pressure required for electrospinning. The nozzle height adjustment module 2 is used to precisely adjust the height of the nozzle 3 . The height of the nozzle 3 is defined as the distance between the printing end and the solar cell to be printed. Nozzle 3 is a direct actuator for printing grid electrodes, including a printing end, a silver paste supply interface and an electrical interface. The nozzle 3 is to be metallized for the establishment of the electric field. The function of the nozzle 3 is: as the positive electrode of the high-voltage electric field, the silver paste forms a Taylor cone at the front end of the nozzle, that is, the printing end, and further pulls out the filament. The high pressure generator 4 is used to apply high pressure between the nozzle 3 and the substrate. The high-voltage generator 4 is connected to the control unit 8, and the voltage can be adjusted conveniently at the computer terminal. The adsorption platform 5 is used to absorb and fix the solar substrate 7 to be printed. The motion platform 6 is used to drive the solar substrate 7 to move in a straight line to complete grid electrode pattern printing. Cooperate with the control unit to complete the printing of desired grid electrode pattern. The control unit 8 is composed of a control card and an industrial computer, so that the whole system can control the process parameters such as voltage, height and speed in real time through the computer interface, so as to realize the numerical control of the printing grid lines.

The silver paste supply device 1 can be composed of a precision flow pump, and can also be composed of a container for storing silver paste and a precision air pressure control valve. Wherein the output control end of the silver paste supply device 1 is connected to the silver paste supply interface of the nozzle 3 . The input control end of the silver paste supply device 1 is electrically connected to the control unit 8 .

The nozzle height adjustment module 2 includes a motor, a slide block and a screw mandrel. The nozzle 3 is fixedly connected with the slide block. The motor is controlled by the control unit 8 to drive the screw rod and the slider to move.

The nozzle 3 can be a single nozzle, or a plurality of nozzles arranged in an array, as shown in FIG. 3 . In principle, a single nozzle can achieve the purpose of improving conversion efficiency, and the structure is simple. However, there is a single nozzle, which requires multiple printings, and the printing efficiency is low. A plurality of nozzles arranged in an array can complete the printing of grid electrodes in a single pass, and the efficiency is high. The front end of the nozzle is the printing end, and the distance between it and the solar substrate 7 is the process parameter we need to control—height. The nozzle is a metal nozzle or the front end is plated with metal. The nozzle needs to have an electrical interface and be connected to the positive pole of the high voltage generator. The silver paste supply interface of the nozzle is the silver paste input end, which is connected with the silver paste supply device.

The high-voltage generator 4 satisfies all output voltages including 0-2.5KV, time drift <0.1%/h, temperature drift <0.1%/°C, and can be remotely controlled by the terminal, that is, any high-voltage generator controlled by computer programming can be used. For example, the model is DW-P503-1AC Dongwen high voltage generator. The control terminal of the high voltage generator is electrically connected to the control unit.

Adsorption platform 5 is fixedly connected with motion platform 6 . The adsorption platform should have an electrical interface to connect to the negative pole of the high voltage generator. As a further optimization, an insulating layer with proper dielectric constant and thickness is provided between the adsorption platform 5 and the printed battery sheet. In order to avoid the breakdown of the cell when printing the silver grid line. The setting of the insulating layer cannot affect the work of the adsorption platform.

The motion platform 6 is an ordinary platform capable of realizing XY two-way movement. As a preferred solution, the repetitive positioning accuracy of the motion platform is preferably less than 5 μm. The motion platform is electrically connected with the control unit 8 .

The solar substrate 7 may be a common solar substrate 7 without grid electrodes printed. The solar substrate 7 is adsorbed and fixed on the adsorption platform 5 .

The control unit 8 can be any control system that can satisfy the above-mentioned purpose. Such as motion control card + industrial computer.

In the embodiment of the present invention, when the printed solar cell is a flexible thin-film solar cell, the feeding of the printed solar cell with the tape is completed by a roll-to-roll device instead of a moving platform. Print with roll-to-roll feed to improve production efficiency. At this time, raster lines are printed continuously. Both the motion platform and the adsorption platform do not work, but it is necessary to ensure that the adsorption platform is connected to the negative pole of the high-voltage generator. As shown in FIG. 4 , the roll-to-roll device 9 includes a discharge roller 90 , a feed roller 91 and a take-up roller 92 . At this time, the flexible solar roll to be printed grid electrodes is placed on the discharge roller 90 . The roll-to-roll device 9 is electrically connected to the control unit 8 . The speed of the feed roller 91 is controlled by the control unit 8 to drive the flexible solar film to move from the discharge roller 90 to the take-up roller 92 , and the grid electrode is printed at the nozzle 3 . The solar cell after printing the grid electrode is rolled up by the take-up roller 92 . During this period, both the motion platform and the adsorption platform do not work, but it is necessary to ensure that the adsorption platform is connected to the negative pole of the high-voltage generator. The method can realize continuous printing of grid lines, that is, continuous manufacturing of flexible solar cells, and improve production efficiency.

In the embodiment of the present invention, Fig. 5 shows that when the feed speed of the substrate is 200mm/s, the nozzle height is 15mm, and the voltage is 1.5kv, the number of rows of different nozzle arrays brings about the variation of the printed raster line spacing; Fig. 5(a ) is 4 mm for the grid line spacing printed by a single row of nozzles, and 2 mm for the grid line spacing printed by two rows of nozzles in Fig. 5(b); the printing grid line spacing can be reduced by increasing the number of columns of the nozzle array. Figure 6 shows that when the nozzle diameter is 150 μm, the feed speed of the substrate is 200 mm/s, and the voltage is 1.5 kv, the height of the printed grid lines is different for different nozzle heights; Figure 6 (a) the height of the nozzle is 8 mm, and the height of the printed grid lines is 15μm; Fig. 6(b) the nozzle height is 15mm, and the grid line height is 20μm; under the same conditions, increasing the nozzle height increases the height of the printing grid line, thereby increasing the aspect ratio. Figure 7 shows that when the nozzle diameter is 150μm and the voltage is 1.5kv, the nozzle height is 15mm, and the width of the printed grid lines is different for different substrate feed speeds; Figure 7(a) speed is 150mm/s, and the printed grid line width is 48μm ; Figure 7(b) speed is 300mm/s, and its grid line width is 30μm; in order to increase the speed of printing the battery substrate under the same other conditions, the printed grid line width is reduced; Figure 8 is the feed speed of the substrate When the voltage is 200mm/s and the voltage is 1.5kv, the nozzle height is 15mm, and the width of the printed raster lines is different for different nozzle diameters; Fig. 8(a) the nozzle diameter is 400μm, and the printed raster line width is 100μm; Fig. 8(b) The diameter of the nozzle is 100 μm, and the width of the grid line is 30 μm; under the same conditions, increasing the height of the nozzle increases the height of the printing grid line, thereby increasing the aspect ratio.

In the embodiment of the present invention, the grid line width of the solar grid electrode prepared by the above-mentioned equipment is at least close to the submicron scale, so that light of many wavelengths in visible light can be diffracted and the shadow area can be reduced. And has a large aspect ratio. Thereby improving the efficiency of the solar cell.

The embodiment of the present invention also proposes a method for directly writing solar cell grid electrodes by using an electrospinning process, the method specifically includes:

(1) The solar substrate 7 is arranged on the adsorption platform;

(2) Prepare the first gate electrode:

(2.1) A nozzle 3 with a diameter of 100-400 microns is arranged on the nozzle height adjustment module 2, and the electrical interface of the nozzle 3 is connected to the high-voltage generator 4, and the silver paste supply interface of the nozzle 3 is connected to 1, The printing end of the nozzle 3 is perpendicular to the substrate;

(2.2) The control unit 8 outputs the first control signal to control the silver paste supply device 1 to inject silver paste into the cavity of the nozzle 3;

(2.3) The control unit 8 outputs the second control signal to control the slider in the nozzle height adjustment module 2 to slide along the screw rod, and adjust the height of the array of nozzles 3 to 0.5-2 cm;

(2.4) The control unit 8 outputs a third control signal to control the high-voltage generator 4 to apply a voltage between the nozzle 3 and the adsorption platform 5; the voltage is set to 0.8-2kv.

(2.5) The control unit 8 outputs a fourth control signal to control the motion platform to move along the X direction at a speed of 150-300 mm/s, and form the first grid electrode;

(3) Preparation of the second gate electrode

(3.1) The nozzle 3 with a diameter of 500-1000 microns is arranged on the nozzle height adjustment module 2, and the electrical interface of the nozzle 3 is connected with the high-voltage generator 4, and the silver paste supply interface of the nozzle 3 is connected to the silver The slurry supply device 1 is connected, and the printing end of the nozzle 3 is perpendicular to the substrate;

(3.2) The control unit 8 outputs the first control signal to control the silver paste supply device 1 to inject silver paste into the cavity of the nozzle 3;

(3.3) The control unit 8 outputs the second control signal to control the slider in the nozzle height adjustment module 2 to slide along the screw rod, and adjust the height of the nozzle array to 0.5-1 cm;

(3.4) The control unit 8 outputs a third control signal to control the high voltage generator 4 to apply a voltage between the nozzle and 5; the voltage is set to 0.8-2kv.

(3.5) The control unit 8 outputs a fourth control signal to control the motion platform 6 to move along the Y direction at a speed of 80-200 mm/s, and form the second grid electrode.

Wherein, the width of the second gate electrode is greater than the width of the first gate electrode, and the distance between the two first gate electrodes is smaller than the distance between the two second gate electrodes.

In the embodiment of the present invention, the control unit 8 includes a motion control card and an industrial computer, which can output the first control signal to control the silver paste supply device 1 to inject silver paste into the cavity of the nozzle 3; output the second control signal to control the height of the nozzle The slider in the adjustment module 2 slides along the screw, and the third control signal is output to control the high voltage generator 4 to apply voltage between the nozzle and 5; the fourth control signal is output to control the motion platform 6 to move at a certain speed along the X or Y direction. sports.

The method for preparing the back electrode of the solar cell provided by the embodiment of the present invention utilizes the electrospinning direct writing process to print the solar electrode. The electrospinning process uses an electric field to pull the silver paste in the nozzle into filaments with a diameter smaller than that of the nozzle. The width and height of the printed raster lines can be controlled by controlling different voltages, nozzle heights, and substrate feed speeds. Among them, the voltage affects the stability of the Taylor cone at a certain height. The height mainly affects the height of the printed grid lines by affecting the solidification degree of the grid lines in the air. Under the condition that other conditions remain unchanged, the higher the height, the higher the height of the printed grid lines. The feeding speed of the substrate mainly affects the width of the printed raster lines. Under the condition that other conditions remain unchanged, the greater the speed, the thinner the raster lines.

Compared with the traditional screen printing method, the method provided by the embodiment of the present invention can print thinner grid lines, achieve a larger aspect ratio, save silver paste, and can print the width and height of the grid lines by numerical control. As an optimization method, the nozzle array is used to complete the grid electrode printing in a single pass, which improves the production efficiency.

In the present invention, in the solar grid electrode structure prepared by the above method, the grid line width is at least close to the submicron scale, so that light of many wavelengths in visible light can be diffracted and the shadow area can be reduced. And the gate lines have a large aspect ratio. Improves the efficiency of solar cells.

In order to further specifically explain the present invention, four embodiments are provided below. Since the printing solar back electrode busbar is the same as the fine grid line process, only the printing of the thin grid line (i.e. the first grid electrode) is aimed at in the embodiment. explained.

Example 1: Now it is necessary to print the upper electrode of an n ⁺ p type monocrystalline silicon solar cell with a side length of 125 mm and a diagonal of 165 mm. The electrode material is silver paste, and its volume resistivity is 3.0uΩ.cm. According to the solar cell Due to the limitations of gate optimization theory and technology, it is calculated that the spacing of fine grid lines should be controlled at about 2.5mm, and the height should be controlled between 10-30um. Further, array nozzles are used to improve production efficiency.

Specific steps are as follows:

(1) The nozzle array is arranged in two rows, placed at equal intervals, each row has 25 nozzles, and the distance between the nozzles is set to 5mm, and the diameter of the nozzles is 200um, so that the theoretical thin grid line spacing printed out is 2.5mm, and the nozzles The width that can be printed is equal to the width of the battery sheet, and the printing of the fine grid can be completed in a single printing.

(2) Place the solar cells to be printed with grid lines on the adsorption platform and absorb them well.

(3) Add the silver paste to be printed into the cavity of the nozzle, and fill the metal nozzle. Connect the nozzle to the positive pole of the high voltage generator, and set the voltage to 1kV;

(4) Adjust the height of the nozzle array, and set the height to 1cm;

(5) Set the X-direction motion speed of the motion platform to 300mm/s;

(6) Start printing, use the Keyence confocal microscope to measure the height of the fine grid is 15um, the width is 30um, to achieve the ideal effect, and complete the printing.

Embodiment 2: On the basis of Embodiment 1, the height of the thin grid is controlled between 15-20um, and the parameters are reset as follows:

(1) The nozzle array is arranged in two rows, placed at equal intervals, each row has 25 nozzles, and the distance between the nozzles is set to 5mm, and the diameter of the nozzles is 300um, so that the theoretical thin grid line spacing printed out is 2.5mm, and the nozzles The width that can be printed is equal to the width of the battery sheet, and the printing of the fine grid can be completed in a single printing.

(2) Place the solar cells to be printed with grid lines on the adsorption platform and absorb them well.

(3) Add the silver paste to be printed into the cavity of the nozzle, and fill the metal nozzle. Connect the nozzle to the positive pole of the high voltage generator, and set the voltage to 1.5kV;

(4) Adjust the height of the nozzle array, and set the height to 1.5cm;

(5) Set the X-direction motion speed of the motion platform to 250mm/s;

(6) Start printing. Using a Keyence confocal microscope, the height of the fine grid is 18um and the width is 35um, which achieves the ideal effect and completes the printing.

Example 3: Now it is necessary to print the upper electrode of a 20mm×20mm n ⁺ p type single crystal silicon solar cell. The electrode material is silver paste, and its volume resistivity is 3.0uΩ.cm. According to the solar cell grid optimization theory and process According to the above restrictions, it is calculated that the spacing of the fine grid lines should be controlled at about 2mm, and the height should be controlled between 20-30um.

Specific steps are as follows:

(1) The nozzle array adopts a single-row layout, a total of 10 nozzles are placed at equal intervals, and the distance between the nozzles is set to 2mm, and the diameter of the nozzles is 400um, so that the theoretical thin grid line spacing printed out is 2mm, and the width that the nozzles can print It is equal to the width of the battery sheet, and the printing of the fine grid can be completed in a single printing.

(2) Place the solar cells to be printed with grid lines on the adsorption platform and absorb them well.

(3) Add the silver paste to be printed into the cavity of the nozzle, and fill the metal nozzle. And connect the nozzle to the positive pole of the high voltage generator. In order to ensure that the thin grid line is as thin as possible, set the voltage to 0.8kV;

(4) Adjust the height of the nozzle array, and set the height to 0.5cm;

(5) Set the X-direction motion speed of the motion platform to 200mm/s;

(6) Start printing. Using a Keyence confocal microscope to observe the grid spacing and thickness of the printed solar cell, the measured fine grid spacing is 2.1mm, the width is 43um, and the height is 21um, which is in line with the preset range of 20-30um. Printed successfully.

Embodiment 4: On the basis of Embodiment 3, the height and voltage of the nozzle were changed, and the changes of the parameters of the thin grid of the solar cell were observed. Specific steps are as follows:

(1) The nozzle array adopts a single row layout, a total of 10 nozzles are placed at equal intervals, and the distance between the nozzles is set to 2mm, and the diameter of the nozzles is 100um, so that the theoretical thin grid line spacing printed out is 2mm, and the width that the nozzles can print It is equal to the width of the battery sheet, and the printing of the fine grid can be completed in a single printing.

(2) Place the solar cells to be printed with grid lines on the adsorption platform and absorb them well.

(3) Add the silver paste to be printed into the cavity of the nozzle, and fill the metal nozzle. And connect the nozzle to the positive pole of the high voltage generator. In order to ensure that the thin grid line is as thin as possible, set the voltage to 2kV;

(4) Adjust the height of the nozzle array, and set the height to 2cm;

(5) Set the X-direction motion speed of the motion platform to 150mm/s;

(6) Start printing. Using a Keyence confocal microscope to observe the grid pitch and thickness of the printed solar cell, it is found that the fine grid pitch is 2.1mm, and the height is 28um, which is slightly higher than that in Example 3, and the grid line width is thinner, 27um .

For the sake of brevity, the data of the busbar (that is, the second grid electrode) in Embodiments 1-4 is shown in Table 1 below:

Table I

The method for preparing the back electrode of the solar battery provided by the invention utilizes an electrospinning direct-writing process to print the solar electrode. The electrospinning process uses an electric field to pull the silver paste in the nozzle into filaments with a diameter smaller than that of the nozzle. The width and height of the printed raster lines can be controlled by controlling different voltages, nozzle heights, and substrate feed speeds. Among them, the voltage affects the stability of the Taylor cone at a certain height. The height mainly affects the height of the printed grid lines by affecting the solidification degree of the grid lines in the air. Under the condition that other conditions remain unchanged, the higher the height, the higher the height of the printed grid lines. The feeding speed of the substrate mainly affects the width of the printed raster lines. Under the condition that other conditions remain unchanged, the greater the speed, the thinner the raster lines.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (4)

1. prepare a method for solar cell gate electrode, it is characterized in that, comprise the steps:

(1) solar base plate is arranged on absorption platform;

(2) first grid electrode is prepared

(2.1) be that the nozzle of 100 ~ 400 microns is arranged in nozzle height adjustment module by diameter, and the electrical interface of described nozzle is connected with high pressure generator, the silver of described nozzle slurry supply interface is starched feedway with silver be connected, the printing end of described nozzle is perpendicular to described solar base plate;

(2.2) control unit exports the first control signal and controls silver slurry feedway to injecting silver slurry in the cavity volume of described nozzle;

(2.3) control unit exports slide block in the second control signal Control Nozzle electronic controlled height adjustment and slides along screw mandrel, and adjustment nozzle array heights is 0.5 ~ 2cm;

(2.4) control unit exports the 3rd control signal control high pressure generator and applies voltage between nozzle and absorption platform; Voltage is set to 0.8 ~ 2kv;

(2.5) control unit output the 4th control signal controlled motion platform moves along X to the speed with 150 ~ 300mm/s, and forms first grid electrode;

(3) prepare second gate electrode, the width of described second gate electrode is greater than the width of described first grid electrode;

The step (3) preparing second gate electrode specifically comprises:

(3.1) be that the nozzle of 500 ~ 1000 microns is arranged in nozzle height adjustment module by diameter, and the electrical interface of described nozzle is connected with high pressure generator, the silver of described nozzle slurry supply interface is starched feedway with silver be connected, the printing end of described nozzle is perpendicular to described solar base plate;

(3.2) control unit exports the first control signal and controls silver slurry feedway to injecting silver slurry in the cavity volume of described nozzle;

(3.3) control unit exports slide block in the second control signal Control Nozzle electronic controlled height adjustment and slides along screw mandrel, and adjustment nozzle array heights is 0.5 ~ 1cm;

(3.4) control unit exports the 3rd control signal control high pressure generator and applies voltage between nozzle and absorption platform; Voltage is set to 0.8 ~ 2kv;

(3.5) control unit output the 4th control signal controlled motion platform moves along Y-direction with the speed of 80 ~ 200mm/s, and forms second gate electrode.

2. the method for claim 1, is characterized in that, the width of described first grid electrode is 5 μm ~ 50 μm, and the height of described first grid electrode is 0.8 μm ~ 30 μm.

3. the method as described in any one of claim 1-2, is characterized in that, the spacing between two first grid electrodes is less than the spacing between two second gate electrodes.

4. the solar energy gate electrode structure adopting the method described in any one of claim 1-2 to prepare.