CN113306320A

CN113306320A - Solar cell metal grid spray printing forming method and device for laser in-situ film opening

Info

Publication number: CN113306320A
Application number: CN202110544560.3A
Authority: CN
Inventors: 张磊; 王修琨; 李朋朋; 刘力; 靳忠尚
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2021-08-27
Anticipated expiration: 2041-05-19
Also published as: CN113306320B

Abstract

The invention discloses a method and a device for forming a metal gate of a solar cell by laser in-situ film opening. In the first step, the SiNx film is in-situ film-opened by using laser technology to form micro-grooves; the second step is using inkjet The printing technology injects metal ink into the micro-grooves; the third step is to adjust the parameters of laser power, defocusing amount, scanning frequency and scanning speed, and then determine the quantitative relationship with the micro-grooves of the film layer to realize the optimization of the micro-grooves of the film layer With precise control, the metal ink is accurately injected into the micro-grooves and heated to form the metal grid of the solar cell. By performing laser in-situ film opening on the substrate before inkjet printing, the requirements of ultra-fine and large "aspect ratio" of the grid electrode of the solar cell are guaranteed, and the complicated process of adding glass powder to the metal ink to be sprayed is avoided. The printing quality is improved, the printing efficiency is improved, and the printing cost is reduced. The cross-printing method is adopted to make the printed grid more uniform, which greatly improves the printing accuracy.

Description

Solar cell metal grid spray printing forming method and device for laser in-situ film opening

Technical Field

The invention relates to a manufacturing method of a solar cell metal grid, in particular to a non-contact ink-jet printing forming manufacturing method of a solar cell metal grid with a laser in-situ film opening function.

Background

The solar cell is one of renewable green energy sources, can directly convert light energy into electric energy, and has the advantages incomparable with the traditional energy sources. The crystalline silicon solar cell occupies 90% of market share as a mainstream product in the current photovoltaic industry, and the photoelectric conversion efficiency is over 24% at most. In the future, the crystalline silicon solar cell still occupies the mainstream of the market by virtue of the advantages of the crystalline silicon solar cell on core indexes such as conversion efficiency, process maturity and service life. In the manufacturing process of the crystalline silicon cell, an electrode is manufactured on the front surface of a silicon wafer to lead out photoelectrons, namely the manufacturing of a crystalline silicon solar cell grid is an extremely important link, and the photoelectric conversion efficiency and the production cost of the solar cell are directly influenced by the process performance of the crystalline silicon solar cell grid.

At present, most commercial crystalline silicon solar cell grids are based on the traditional contact screen printing technology, and the damage rate of the crystalline silicon wafer is high due to the contact manufacturing process. Meanwhile, due to the restriction of the particle size of the printing slurry and the mesh precision of the printing screen, the width of the formed grid is difficult to be lower than 60 mu m, and the manufacturing precision of the grid cannot be ensured. In addition, the screen printing process also has the problem of waste of precious metal paste. And the ink jet printing technology is considered as a new generation solar cell grid manufacturing technology to replace the traditional screen printing.

The ink-jet printing technology is a non-contact manufacturing process, can directly and accurately print on a silicon wafer under the condition of no contact with the silicon wafer, can reduce the width of a grid to be below 40 mu m, can realize non-uniform distribution of grid appearance according to design requirements, has high material utilization rate and simple process, and can be better realized in the grid manufacturing of a thin-sheet battery and a flexible battery compared with the traditional contact screen printing technology.

For solar cells, surface texturing and silicon nitride (SiNx) antireflection coatings are typically used to reduce light reflection in order to achieve sufficient absorption of solar rays. At present, in the prior art of ink-jet printing, a glass powder formula needs to be added into metal ink for ink-jet printing to etch through an insulating SiNx film, so that the aim of forming good ohmic contact between metal particles and a silicon substrate is fulfilled. However, the glass powder required in the ink-jet printing process has extremely high technological requirements in the preparation of nano-powder and the good dispersion of an ink system, and the core technology of the glass powder is monopolized by a few foreign companies all the time. Meanwhile, the dynamics behavior of Ag/Si ohmic contact formed by the glass powder and the SiNx film ablated by the silver particles is very complex, and the forming mechanism of the Ag/Si contact interface is not clear up to now. Therefore, how to effectively remove the SiNx film layer at low cost when the metal gate is subjected to spray printing is a key point for large-scale application of the spray printing metal gate.

Disclosure of Invention

The invention aims to provide a laser in-situ membrane-opening solar cell metal grid non-contact ink-jet printing forming manufacturing method, which improves the printing quality, improves the printing efficiency and reduces the printing cost. By adopting the cross printing method, the printed grid is more uniform, and the printing precision is greatly improved.

The technical scheme adopted by the invention is as follows:

a solar cell metal grid spray printing forming method for laser in-situ film opening comprises the following steps:

firstly, carrying out in-situ film opening on the SiNx film by using a laser technology to form a micro groove;

secondly, injecting the metal ink into the micro-grooves by using an ink-jet printing technology;

and thirdly, adjusting laser power, defocusing amount, scanning frequency and scanning speed parameters to further determine the quantitative relation with the film micro-groove, realizing optimization and accurate control of the film micro-groove, ensuring that metal ink is accurately injected into the micro-groove, and heating to form the solar cell metal grid.

A solar cell metal grid spray printing forming device for laser in-situ film opening comprises a controller, a conveying device, a vacuum heating adsorption platform, an ink-jet printing system and a laser ablation device;

the controller is provided with a laser ablation device connected with the ink-jet printing system; the controller is connected with the conveying device by adopting a high-precision servo control system;

the conveying device loads the polycrystalline silicon wafer through the vacuum heating adsorption platform, and the conveying device transmits the polycrystalline silicon wafer to the laser ablation device by adopting anticlockwise rotation;

the laser ablation device is parallel to an X axis of a high-precision servo control system of the controller, in-situ film opening is carried out on a SiNx film layer on the surface of the polycrystalline silicon wafer on the vacuum heating adsorption table, and a micro groove is formed on the surface of the polycrystalline silicon wafer; then conveying the polysilicon silicon wafer subjected to laser in-situ membrane opening to an ink-jet printing forming system by a conveying device;

the ink-jet printing system consists of a plurality of ink-jet printing groups, each group comprises four ink-jet printing heads, each nozzle is provided with a nozzle base, and the ink-jet printing system has dual functions of adjustment and cooling; each group of ink-jet printing heads is fixed by a nozzle fixing seat so as to facilitate water cooling and accurate calibration; when the polycrystalline silicon wafer moves to the lower end of the ink-jet printing system, the controller starts to control the ink-jet printing head to jet ink, and the jetted liquid drops immediately drop into the pre-opened micro-groove, so that the metal grid of the solar cell is printed.

The invention has the following beneficial effects:

1. according to the invention, a laser technology is introduced into an ink-jet printing forming process of the crystalline silicon solar cell grid electrode, after the film is opened in situ by laser, metal ink to be sprayed, namely nano-silver ink, is directly ink-jet printed into the micro-groove, and compared with the traditional screen printing method, the precision can not be ensured, the solar cell grid electrode printed by the solar cell metal grid electrode spray printing forming manufacturing method of the film is higher in precision; compared with the traditional ink-jet printing method, the preparation method of the metal ink has the advantages that the glass powder of a non-conductor is not required to be added into the metal ink, and the preparation of the metal ink is greatly simplified.

2. According to the solar cell grid electrode spray printing forming process adopting laser in-situ film opening, the SiNx film is subjected to in-situ film opening through laser to form a micro-groove structure, and liquid drops are accurately dripped into the pre-manufactured micro-groove structure through an ink-jet printing system, so that the micro liquid drops are guided to form directional transportation. The method is beneficial to forming a characteristic pattern with high resolution, realizes the manufacture of the metal grid with superfine and large height-width ratio, and improves the printing efficiency.

3. The grid manufactured by adopting the cross printing method has higher uniformity and reliability compared with the traditional continuous printing mode.

Drawings

FIG. 1 is a schematic structural diagram of a laser in-situ membrane-opening inkjet printing system according to the present invention.

FIG. 2 is a schematic diagram of a single set of inkjet printing systems.

FIG. 3 is a schematic diagram of a single row nozzle cross-jet printing method.

FIG. 4 is a schematic view of a cross-jet printing method in the X-axis direction.

The printing system comprises a laser source 100, a high-speed galvanometer 110, a polycrystalline silicon chip 120, an ink jet printing head 130, a conveying device 140, a controller 150, a micro groove 160, a nozzle base 170, a vacuum adsorption heating table 180, a nozzle fixing seat 190, an ink jet printing system 210, a SiNx film on the surface of 220, a liquid drop 300, an odd-numbered liquid drop 300A and an even-numbered liquid drop 300B.

Detailed Description

The invention will be described in further detail with reference to the accompanying figures 1-4 and examples.

The solar cell grid line electrode is usually long and has high requirements on the aspect ratio, and the traditional screen printing technology can generate deviation accumulation in the manufacturing process, so that the precision cannot be achieved. The laser in-situ film opening technology can well solve the problems that the aspect ratio and the forming precision of the grid line electrode can be guaranteed by adopting the ink-jet printing technology, and meanwhile, the process difficulty is increased by adopting glass powder in the common ink-jet printing technology.

In the third step, glass powder of a non-conductor is not required to be added, so that the preparation of the metal ink is simplified, and the good silver/silicon (Ag/Si) ohmic contact is formed;

the specific process is as follows: the solar cell polycrystalline silicon wafer firstly passes through a laser ablation device along the X-axis direction of a high-precision servo system, and is subjected to in-situ film opening by the laser ablation device to form a micro groove;

after the micro-groove is formed, the solar cell polycrystalline silicon wafer directly enters an ink-jet printing control area through a high-precision servo system to perform spray printing forming on a grid line electrode of the solar cell, a spray head is static in the process, and grid spray printing forming is completed in the process that the cell moves along the X-axis direction; the micro-groove with the film opened in situ is parallel to the grid formed by ink-jet printing in the X-axis direction, so that the nano-silver ink sprayed by the spray head can be accurately deposited into the micro-groove;

and after the spray printing of the solar cell polycrystalline silicon wafer is finished, carrying out ink-jet printing forming on the next solar cell polycrystalline silicon wafer according to the step to form the solar cell metal grid.

According to the spray printing forming manufacturing process, the invention provides the spray printing forming method of the solar cell grid line electrode applied to laser in-situ film opening, and the method adopts a cross printing mode, so that the spray printing forming system of the solar cell grid line electrode can manufacture the grid electrode with high height-width ratio and uniform distribution on the polycrystalline silicon chip, and the forming reliability of the grid electrode is ensured.

A solar cell metal grid spray printing forming device for laser in-situ film opening comprises a controller 150, a conveying device 140, a vacuum heating adsorption table 180, an ink-jet printing system 210 and a laser ablation device;

the controller 150 is provided with a laser ablation device connected with the inkjet printing system 210; the controller 150 is connected with the conveying device 140 by adopting a high-precision servo control system;

the conveyer 140 loads the polysilicon wafer 120 through the vacuum heating adsorption table 180, and the conveyer 140 rotates counterclockwise to transmit the polysilicon wafer 120 to the laser ablation device;

the laser ablation device is parallel to the X axis of the high-precision servo control system of the controller 150, performs in-situ film opening on the SiNx film layer 220 on the surface of the polycrystalline silicon wafer 120 on the vacuum heating adsorption table 180, and forms a micro groove 160 on the surface of the polycrystalline silicon wafer 120; then the conveyer 140 conveys the polysilicon silicon wafer 120 after laser in-situ membrane opening to the ink-jet printing forming system 210;

the inkjet printing system 210 is composed of several inkjet printing groups, each group including four inkjet print heads 130, each head having a head base 170, which has dual functions of adjustment and cooling; each set of inkjet print heads is fixed by a nozzle fixing base 190 to facilitate water cooling and accurate calibration; when the polysilicon wafer 120 moves to the lower end of the inkjet printing system, the controller 150 starts to control the inkjet printing head 130 to jet ink, and the jetted droplets 300 immediately drop into the pre-opened micro-grooves 160, so as to complete the printing of the solar cell metal grid.

The cross printing mode is adopted on the micro-grooves, so that the spray printing forming system can manufacture the grid electrodes with high height-width ratio and uniform distribution on the polysilicon silicon chip, and the forming reliability of the grid electrodes is ensured;

the cross printing mode specifically comprises the following steps:

the transverse direction is the X-axis direction, and a dot printing mode is adopted, namely in the process of multi-layer printing, each layer adopts dot printing, and the droplets printed in the next layer are deposited on the gaps of the previous layer;

the liquid drops printed by the isolated points are divided into odd-numbered liquid drops 300A and even-numbered liquid drops 300B, the two liquid drops are ejected in a staggered mode, deposited in the micro grooves 160 and pass through the vacuum heating adsorption table 180, and then the uniform and smooth solar cell metal grid is formed.

The ink jet printing system 210 may include a plurality of ink jet printing groups, wherein the number of the ink jet printing groups is determined according to the number of printing layers and the number of prints required for the grid line electrode of the solar cell, and the conveying device conveys the polysilicon wafer through each group of ink jet printing heads, thereby completing the whole printing process to form the metal grid of the solar cell.

As shown in fig. 1 and 2, after the controller 150 is turned on, the system starts to operate; the polysilicon silicon chip 120 to be jet printed is placed on the conveying device 140 and moves along the clockwise direction; a laser ablation device consisting of a laser light source 100 and a high-speed galvanometer 110 forms a micro-groove 160 on the surface of the polysilicon silicon wafer 120, and then the polysilicon silicon wafer 120 subjected to laser in-situ membrane opening is conveyed to an ink-jet printing system 210 by a conveying device 140; the inkjet printing system 210 is composed of a plurality of inkjet printing groups, each inkjet printing group includes four inkjet printing heads 130, each inkjet printing head has a nozzle base 170, and the inkjet printing system has dual functions of adjustment and cooling; each set of inkjet print heads is fixed by a nozzle fixing base 190 to facilitate water cooling and accurate calibration; when the polysilicon wafer 120 moves to the lower end of the inkjet printing system 210, the controller 150 starts to control the inkjet printhead 130 to eject ink, and the ejected droplets 300 immediately drop into the pre-opened micro-grooves 160 to be printed into a gate. In the implementation, the micro-grooves formed by laser in-situ film opening are parallel to the grid formed by ink-jet printing in the X-axis direction, so that the liquid drops sprayed by the ink-jet printing head can be accurately deposited in the micro-grooves.

As shown in fig. 3, the SiNx film 220 on the surface of the polysilicon silicon wafer 120 is processed by a laser ablation device to form a micro-groove 160, and then the inkjet print head 130 is controlled to perform jet printing, wherein the inkjet print head 130 is controlled to adopt a cross printing mode, i.e., dot printing, and the liquid drops printed by the dot printing are divided into odd-numbered liquid drops 300A and even-numbered liquid drops 300B, and the two liquid drops are alternately ejected and deposited in the micro-groove 160 and pass through the vacuum heating adsorption stage 180, so as to form a uniform and smooth gate.

As shown in fig. 4, in the X-axis direction, the inkjet printhead 130 first ejects odd-numbered droplets 300A and forms a first deposition layer L1, and then even-numbered droplets 300B are deposited on the gaps between the odd-numbered droplets of the first deposition layer L1 and form a second deposition layer L2, and the first deposition layer and the second deposition layer form a first inkjet layer; the second spray printing layer method is the same as the first spray printing layer (L3 is deposited on L1, L4 is deposited on L2), thereby forming a uniform solar cell metal grid.

The substrate is subjected to laser in-situ membrane opening in advance before ink-jet printing, so that the requirements of superfine and large height-to-width ratio of the solar cell grid line electrode are met, the complex process of adding glass powder into metal ink to be sprayed is avoided, the printing quality is improved, the printing efficiency is improved, and the printing cost is reduced. By adopting the cross printing method, the printed grid is more uniform, and the printing precision is greatly improved.

Claims

1. a solar cell metal grid printing forming method of laser in-situ film opening, is characterized in that,

It includes the following steps:

The first step is to use laser technology to open the SiNx film in-situ to form micro-grooves;

In the second step, the metal ink is injected into the micro-grooves using inkjet printing technology;

The third step is to adjust the parameters of laser power, defocus, scanning frequency and scanning speed, and then determine the quantitative relationship with the micro-grooves of the film layer, realize the optimization and precise control of the micro-grooves of the film layer, and ensure that the metal ink is accurately injected into the micro-grooves. In the groove, the metal grid of the solar cell is formed by heating.

2. a kind of laser in-situ film-opening method according to claim 1, characterized in that,

The third step does not need to add non-conductive glass powder, which simplifies the preparation of metal ink and helps to form a good silver/silicon ohmic contact;

The specific process is as follows: the solar cell polycrystalline silicon wafer first passes through the laser ablation device along the X-axis direction of the high-precision servo system, and the laser ablation device is used to open the film in situ to form micro-grooves;

When the micro-grooves are formed, the solar cell polycrystalline silicon wafers directly enter the inkjet printing control area through the high-precision servo system, and the grid line electrodes of the solar cell are jetted and formed. In this process, the nozzle is stationary, and the cell is moved along the X-axis. The gate is formed by jet printing; since the micro-grooves of the in-situ film opening are parallel to the gate formed by ink-jet printing in the X-axis direction, the nano-silver ink jetted by the nozzle can be accurately deposited into the micro-grooves;

After the inkjet printing of the solar cell polycrystalline silicon wafer is completed, the next solar cell polycrystalline silicon wafer is still formed by inkjet printing according to this step to form the solar cell metal grid.

3. a solar cell metal grid spray-printing forming device for laser in-situ film opening, is characterized in that,

Including controller, transfer device, vacuum heating adsorption table, inkjet printing system, laser ablation device;

A laser ablation device is installed on the controller to connect with the inkjet printing system; the controller adopts a high-precision servo control system to connect with the transmission device;

The transfer device loads the polysilicon wafers through the vacuum heating adsorption table, and the transfer device rotates counterclockwise to transfer the polysilicon wafers to the laser ablation device;

The laser ablation device is composed of a laser light source and a high-speed galvanometer. The laser ablation device is parallel to the X-axis of the high-precision servo control system of the controller. Micro-grooves are formed on the surface of the silicon wafer; then the polysilicon wafer after laser in-situ film opening is transported to the inkjet printing molding system by the conveying device;

The inkjet printing system consists of several inkjet printing groups, each group contains four inkjet printing heads, and each nozzle has a nozzle base, which has dual functions of adjustment and cooling; each group of inkjet printing heads is composed of The nozzle holder is fixed to facilitate water cooling and accurate calibration; when the polysilicon wafer moves to the lower end of the inkjet printing system, the controller starts to control the inkjet printing head to eject ink, and the ejected droplets immediately drop to the pre-opened micro-channel. The grooves are then printed to complete the metal grid of the solar cell.

4. The solar cell metal gate spray-printing forming device for laser in-situ film opening according to claim 3, characterized in that, a cross-printing mode is adopted on the micro-grooves, which enables the spray-printing forming system to be A gate with a high "aspect ratio" and a uniform distribution is fabricated on the chip to ensure the reliability of gate formation;

The cross print mode is specifically:

The horizontal direction is the X-axis direction, and the interval printing mode is adopted, that is, in the process of multi-layer printing, each layer is printed at intervals, and the droplets printed on the next layer are deposited on the gap of the previous layer;

The droplets printed at every point are divided into odd-numbered droplets and even-numbered droplets. The two kinds of droplets are sprayed alternately, deposited in the micro-grooves, and heated by the vacuum adsorption table to form a uniform and smooth solar cell. Metal gate.

5. A kind of laser in-situ film-opening solar cell metal gate jet printing forming device according to claim 3, is characterized in that,

The inkjet printing system can include multiple inkjet printing groups, wherein the number of inkjet printing groups is determined according to the number of printing layers and the number of printings required for the grid electrode of the solar cell. The conveying device transports the polysilicon wafers through each group. Inkjet print head, thus completing the entire printing process to form the metal grid of the solar cell.

6. A kind of laser in-situ film-opening solar cell metal gate spray-printing forming device according to claim 3, characterized in that,

The inkjet print head first ejects odd-numbered droplets to form deposition layer 1, and then even-numbered droplets are deposited on the gap between odd-numbered droplets of deposition layer 1 to form deposition layer 2, and deposition layer 1 and deposition layer 2 form deposition layer 1. The spray-printed layer; the method of the second spray-printed layer is the same as that of the first spray-printed layer, so as to form a uniform metal grid of the solar cell.