CN116487473A - IBC battery and preparation method thereof - Google Patents

Abstract

An embodiment of the present invention provides an IBC battery and a preparation method thereof, wherein, in the embodiment of the present invention, silver-aluminum paste is printed on the first area of the anti-reflection film layer on the back of the silicon wafer, and silver paste is printed on the second area of the anti-reflection film layer on the back of the silicon wafer. Because the silver powder in the silver-aluminum paste has a good burn-through property, it can burn through the anti-reflection film layer and the passivation film layer successively. After high-temperature sintering, it contacts with the p+ doped area to form a positive electrode grid line, which saves the step of secondary laser grooving and avoids damage to the passivation layer caused by secondary laser grooving. Moreover, the series resistance of the silver-aluminum paste is smaller than that of the traditional aluminum paste, and the recombination rate and degree of recombination will also be greatly improved, which can increase the open circuit voltage of the battery, thus solving the problem that the existing P-type IBC battery needs to laser groove the P+ area when printing the positive grid line, resulting in a decrease in the open circuit voltage value of the cell.

Description

A kind of IBC battery and preparation method thereof

technical field

The invention relates to the technical field of manufacturing crystalline silicon solar cells, in particular to an IBC cell and a preparation method thereof.

Background technique

Interdigitated Back Contact (IBC) battery is a new type of battery in which the P/N junction, the contact electrodes of the substrate and the emitter region are interdigitated on the back of the battery.

At present, P-type IBC batteries need to laser groove the P+ region before printing the grid lines to facilitate the printing of aluminum paste to form positive grid lines. However, laser grooving not only increases the manufacturing process, but also damages the passivation layer, resulting in a decrease in the open circuit voltage of the battery.

Contents of the invention

The technical problem to be solved by the present invention is to provide an IBC battery and its preparation method to solve the problem that the existing P-type IBC battery needs to perform laser slotting on the P+ region when printing the positive grid line, resulting in a decrease in the open circuit voltage value of the battery sheet.

In order to solve the above problems, the present invention is achieved through the following technical solutions:

The present invention proposes a preparation method of an IBC battery, including:

After sequentially forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer, phosphorus doping is performed on the back polysilicon layer;

Laser grooves on the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

After laser grooving, a passivation film layer and an anti-reflection film layer are formed on both sides of the silicon wafer;

Print silver-aluminum paste on the first area of the anti-reflection film layer on the back of the silicon wafer, and print silver paste on the second area of the anti-reflection film layer on the back of the silicon wafer; the projection of the first area is within the range of the p+ doped area, and the projection of the second area is within the range of the n+ doped area;

The P-type silicon wafer printed with silver-aluminum paste in the first region and silver paste in the second region is sintered at high temperature to produce an IBC battery.

Further, in the preparation method, the components constituting the silver-aluminum paste include organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder.

Further, in the preparation method, in the silver-aluminum paste, the mass percentage of the organic additive is 0.4-0.6%; the mass percentage of the silver powder is 65-75%; the mass percentage of the aluminum powder is 3-5%; the mass percentage of the boron aluminum alloy powder is 0.05-0.1%; the mass percentage of the organic binder is 17.5-30.55%; the mass percentage of the glass powder is 1-1.8%.

Further, in the preparation method, the aluminum powder includes micron-sized spherical aluminum powder and nano-sized spherical aluminum powder, the silver powder includes micron-sized spherical silver powder and nano-sized spherical silver powder, and the boron-aluminum alloy powder is micron-sized boron-aluminum alloy powder.

Further, in the preparation method, the organic additive includes at least one of silane coupling agent, lauryl phosphate, silicone oil, and dibasic acid ester.

Further, in the preparation method, the passivation layer is an aluminum oxide layer, and the anti-reflection film layer is a silicon nitride layer.

Further, before sequentially forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer, the method further includes:

Carry out alkali polishing treatment to described silicon chip;

Before forming a passivation film layer and an anti-reflection film layer on both sides of the silicon wafer, the method also includes:

Carry out chain pickling and texturing treatment on silicon wafers after laser grooving.

Further, before sequentially forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer, the method further includes:

Carry out texture processing to described silicon chip;

Before forming a passivation film layer and an anti-reflection film layer on both sides of the silicon wafer, the method also includes:

Perform chain pickling and alkali polishing on silicon wafers after laser grooving.

Further, in the preparation method, the size of the squares after the alkali polishing treatment is 8-12 microns.

The present invention also proposes an IBC battery, which is prepared by the above method.

Compared with the prior art, the embodiments of the present invention include the following advantages:

In the embodiment of the present invention, after forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer in sequence, the polysilicon layer on the back is doped with phosphorus, and then laser grooves are made on the back of the phosphorus-doped P-type silicon wafer to form n+ doped regions and p+ doped regions arranged in interdigitated intervals, and then a passivation film layer and an anti-reflection film layer are formed on both sides of the silicon wafer; silver-aluminum paste is printed on the first area of the anti-reflection film layer on the back of the silicon wafer, and silver paste is printed on the second area of the anti-reflection film layer on the back of the silicon wafer. Within the range of the p+ doped region, the projection of the second region is within the range of the n+ doped region; then, the P-type silicon wafer printed with silver-aluminum paste in the first region and printed with silver paste in the second region is subjected to high-temperature sintering to obtain an IBC battery. By printing silver-aluminum paste on the first area of the anti-reflection film layer on the back of the silicon wafer, and printing silver paste on the second area of the anti-reflection film layer on the back of the silicon wafer, because the silver powder in the silver-aluminum paste has good burn-through properties, it can burn through the anti-reflection film layer and the passivation film layer successively. After high-temperature sintering, it contacts with the p+ doped area to form a positive grid line, which saves the step of secondary laser slotting and avoids damage to the passivation layer caused by secondary laser slotting. In addition, the series resistance of silver-aluminum paste is smaller than that of traditional aluminum paste, and the recombination rate and recombination degree will also be improved. It has been greatly improved and can increase the open circuit voltage of the battery, thus solving the problem that the existing P-type IBC battery needs to perform laser slotting on the P+ area when printing the positive grid line, resulting in a decrease in the open circuit voltage of the battery sheet.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Description of drawings

Fig. 1 is a flow chart of the preparation method of the IBC battery provided by the embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The applicant of the present invention found that the open circuit voltage of the current P-type IBC battery is reduced by 30mV before and after metallization, and the P-type IBC battery needs to perform laser grooving on the P+ region before printing the grid lines to facilitate the printing of aluminum paste to form positive grid lines.

In order to solve the above problems, the embodiment of the present invention provides a method for preparing an IBC battery, which includes steps 101 to 105:

Step 101, after sequentially forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer, doping the back polysilicon layer with phosphorus;

Step 102, laser grooving the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

Step 103, after laser grooving, form a passivation film layer and an anti-reflection film layer on both sides of the silicon wafer;

Step 104, printing silver-aluminum paste on the first area of the anti-reflection film layer on the back of the silicon wafer, and printing silver paste on the second area of the anti-reflection film layer on the back of the silicon wafer; the projection of the first area is within the range of the p+ doped area, and the projection of the second area is within the range of the n+ doped area;

Step 105, performing high-temperature sintering on the P-type silicon wafer printed with silver-aluminum paste in the first region and printed with silver paste in the second region to produce an IBC battery.

In the embodiment of the present invention, by adding silver powder to the aluminum paste, not only because the silver powder has a good burn-through property, but also when the silver-aluminum paste is printed on the anti-reflection film layer on the back of the silicon wafer, the anti-reflection film layer and the passivation film layer can be sequentially burned through, and then contact with the p+ doped area to form a positive grid line, which saves the step of secondary laser slotting and avoids damage to the passivation layer caused by secondary laser slotting. In addition, the silver-aluminum paste has better contact with the cell itself, and the series resistance is smaller than that of traditional aluminum paste. The recombination rate and recombination degree will also be greatly improved , The opening voltage of the battery can be increased by 5 millivolts, thus solving the problem that the existing P-type IBC battery needs to perform laser slotting on the P+ area when printing the positive grid line, resulting in a decrease in the open circuit voltage of the battery sheet.

In the above step 101, take the P-type original silicon wafer, and use Low Pressure Chemical Vapor Deposition (LPCVD) to form a layer of ultra-thin silicon oxide on the back of the P-type silicon wafer as an ultra-thin tunneling oxide layer, and then prepare a polysilicon layer with a thickness that can meet the passivation effect on both sides; the thickness can be specifically 100-200nm, for example, 150nm. Among them, because the polysilicon layer prepared on both sides is conducive to the subsequent removal of the front polysilicon layer, it is not easy to occur the two extreme situations of excessive removal or insufficient removal, and the yield rate is better controlled.

In the above step 101, after preparing the polysilicon layer, the silicon wafer is sent into the furnace tube, so as to perform phosphorus doping on the polysilicon layer to form an n+ doped region.

In the above step 102, laser grooves are performed on the back of the silicon wafer to expose the p+ doped region to form interdigitated n+ doped regions and p+ doped regions arranged at intervals, and then the front polysilicon layer is removed by wet method. In this step, specifically, the phosphosilicate glass coated on the front side can be removed by using the principle of reacting the lye with the phosphosilicate glass by using a chain machine to remove the film on one side.

Optionally, when performing laser grooving on the back of the silicon wafer, the laser uses picosecond green light to perform grooving by laser marking with a pulse width of 0.8 picoseconds and a pulse number of 2; the laser marking speed is 32000-38000mm/s, the laser power is 15-20w, and the frequency is 1000-1500Hz. The width of the groove after the laser is 280-320 microns and the depth is 1-3 microns.

For example, the rated power of the above-mentioned laser is 30w, and the laser marking is carried out at 600‰ of the rated power, that is, 18w. The laser marking speed is 35000mm/s, the frequency is 1200Hz, and a laser groove with a width of 300 microns and a depth of 2 microns is formed.

In the above step 103, an atomic layer deposition (Atomic Layer Deposition, ALD) process is used to plate a passivation layer on the entire front and back of the product to form field passivation; after the aluminum oxide film is formed, an anti-reflection film is first coated on the front of the battery, and then an anti-reflection film is coated on the back to further improve the passivation effect of the battery.

Optionally, the above-mentioned passivation layer is an aluminum oxide film layer, that is, an aluminum oxide film layer is plated on the entire front side and the entire back side as the above-mentioned passivation layer.

Optionally, the above-mentioned anti-reflection film layer is a silicon nitride layer, that is, the entire front and the entire back are coated with a silicon nitride layer as the above-mentioned anti-reflection film; wherein, the above-mentioned anti-reflection film includes a multi-layer silicon nitride layer, which can further improve the anti-reflection effect.

In the above step 104, the silicon wafer formed with the anti-reflection film is screen-printed to prepare electrode grid lines. Specifically, silver-aluminum paste is printed on the first area of the anti-reflection film layer on the back of the silicon wafer. The projection of the first area is within the range of the p+ doped area to form a positive grid line that is connected to the p+ doped area; at the same time, it is also necessary to print silver paste on the second area of the anti-reflection film layer on the back. The projection of the second area is within the range of the n+ doped area to form a negative grid line spaced from the positive grid line.

Optionally, in one embodiment, the components constituting the silver-aluminum paste include organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder.

Among them, silver powder and aluminum powder are the main components, aluminum powder mainly replaces the P+ emitter of the battery, and silver paste has good thermal conductivity, electrical conductivity and burn-through performance; glass powder is an inorganic adhesive, which will melt into a liquid state under high temperature conditions, and will condense when cooled to play a role in bonding; organic binder can ensure the overall bonding effect; organic additives can reduce the overall viscosity of silver paste; because boron aluminum alloy powder can be mixed with metal aluminum liquid, boron can be introduced to the silicon surface and boron can be diffused into the silicon for heavy doping, which is conducive to improving the paste Excellent contact performance, reducing the reaction contact surface between aluminum and silicon; the above-mentioned silver-aluminum paste can quickly form a good alloy with silicon at a lower sintering temperature, and reduce the contact resistivity between the front silver-aluminum fine grid and the battery, thereby improving the filling of the battery and the efficiency of the battery.

Optionally, in one embodiment, in the above silver-aluminum paste, the mass percentage of organic additives is 0.4-0.6%; the mass percentage of silver powder is 65-75%; the mass percentage of aluminum powder is 3-5%; the mass percentage of boron aluminum alloy powder is 0.05-0.1%; the mass percentage of organic binder is 17.5-30.55%;

For example, in the silver-aluminum paste, the mass fractions of organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder are 0.4%, 77%, 3%, 0.1%, 17.7% and 1.8%, respectively.

For example, in the silver-aluminum paste, the mass fractions of organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder are 0.6%, 65%, 5%, 0.05%, 28.35% and 1%, respectively.

For example, in the silver-aluminum paste, the mass fractions of organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder are 0.5%, 75%, 4%, 0.75%, 18.25% and 1.5%, respectively.

For example, in the silver-aluminum paste, the mass fractions of organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder are 0.4%, 65%, 3%, 0.05%, 30.55% and 1%, respectively.

Optionally, in one embodiment, the aluminum powder includes micron-sized aluminum powder with a mass fraction of 75-80% and a D50 of 5-6 μm, and a micron-sized aluminum powder with a mass fraction of 20-25% and a D50 of 9-10 μm; the silver powder includes a micron-sized silver powder with a mass fraction of 88-94% and a nano-sized silver powder with a mass fraction of 6-12%. The spherical aluminum powder is 5-6 μm, and the spherical aluminum powder has a purity of 3 9s and a mass fraction of 20-25% and a D50 of 9-10 μm. The silver powder is a micron-scale spherical silver powder with a purity of 3 9s and a mass fraction of 88-94%, and a nano-scale spherical silver powder with a purity of 3 9s and a mass fraction of 6-12%. In the embodiment of the present invention, the above-mentioned silver powder is a micron-sized spherical silver powder with a purity of three nines. Wherein, because there is a gap between the micron-sized silver powder and the silver powder, and there is a gap between the micron-sized aluminum powder and the aluminum powder, the above-mentioned nano-sized spherical silver powder can just fill and penetrate into the gap between the micron-sized.

The above-mentioned boron-aluminum alloy powder is a micron-sized boron-aluminum alloy powder, which has the characteristics of high tap density, low oxygen content and high activity. By adding the micron-sized boron-aluminum alloy powder, the silver-aluminum paste can quickly form a good alloy with silicon at a lower sintering temperature, and reduce the contact resistivity between the front silver-aluminum fine grid and the battery.

Optionally, in one embodiment, the organic additive includes at least one of silane coupling agent, lauryl phosphate, silicone oil, and dibasic acid ester.

In the aluminum paste for IBC batteries provided in the embodiments of the present invention, the above-mentioned organic binder includes a polymer resin and an organic solvent; wherein the polymer resin is dissolved in an organic solvent, so that the organic solvent can be used as an organic binder, that is, the slurry can be used to bind powder after drying.

Optionally, in one embodiment, the mass fraction of the above-mentioned high molecular polymer in the organic binder is 9-15%; the mass fraction of the above-mentioned organic solvent in the organic binder is 85-91%.

Optionally, in one embodiment, the above-mentioned high molecular polymer is one or more of ethyl cellulose-N20, ethyl cellulose N-50, and ethyl cellulose-N100;

The above-mentioned organic solvents include at least four of benzyl alcohol, diethyl phthalate, terpineol, butyl carbitol, butyl carbitol acetate, tributyl citrate, Span 85 and alcohol ester twelve.

Optionally, in one embodiment, in parts by mass, the above-mentioned glass powder is obtained by sintering and pulverizing 20-25 parts of Bi ₂ O ₃ , 6-8 parts of Al ₂ O ₃ , 10-12 parts of SiO ₂ , 5-29 parts of ZnO, 15-20 parts of Sb ₂ O ₅ , 5-20 parts of BaO, 5-8 parts of B ₂ O ₃ , and 15-22 parts of TeO _{3 . 0} is 1.2-2 μm, D50 is less than 1.2 μm, the glass activity is too large, and D50 is greater than 2 μm, the glass activity is too small.

Among them, Bi ₂ O ₃ is the main network structure, ZnO can break the network structure and promote glass crystallization, Al ₂ O ₃ can adjust glass stability and increase viscosity; SiO ₂ is used as a glass network former to promote glass stability and increase glass melting point; Sb ₂ O ₅ is used to clarify and uniform glass liquid; BaO is used for local crystallization; B ₂ O ₃ is a network body; and TeO ₃ reduces the glass formation temperature. The D50 of the glass powder is 1.5-2 μm.

In the above step 105, the above-mentioned silver-aluminum paste is solidified by high-temperature sintering, and the silver-aluminum paste is used to burn through the anti-reflection film layer and the passivation layer at the above-mentioned first region to form a positive electrode grid line in contact with the p+ doped region, and at the same time, the above-mentioned silver paste is solidified by high-temperature sintering, and the silver paste is used to burn through the anti-reflection film layer and passivation layer at the above-mentioned second region to form a negative electrode grid line in contact with the n+ doped region, thereby producing an IBC battery.

Optionally, the above-mentioned high-temperature sintering temperature is 750-800°C, for example, 750°C, 766°C or 800°C.

Optionally, in an implementation manner, step 1001 is further included before step 101 above, and step 1031 is further included before step 103 above.

Step 1001, performing alkali polishing on the silicon wafer.

Step 1031 , performing chain pickling and texturing on the silicon wafer after laser grooving.

In step 1001, the purpose of the alkali polishing treatment is to remove the surface damage from the cutting process of the original sheet; at the same time, the alkali polishing treatment also increases the surface area of the cell to prepare for increasing the junction area for diffusion.

In step 1031, before forming the passivation film layer and the anti-reflection film layer on both sides of the silicon wafer, chain pickling can also be performed, and then double-sided texturing can be performed by wet method.

Among them, chain pickling is to use pickling to remove Al, Fe, Zn, Ni and other metal impurities on the surface of silicon wafers, as well as remove metal hydroxides attached to the natural oxide film; and double-sided texturing can greatly reduce the surface reflectance of cells.

In practical application, the monocrystalline silicon wafer can be anisotropically etched with alkaline solution to form a textured surface. The reaction principle is as follows: Si+2NaOH+H ₂ O=Na ₂ SiO ₃ +2H ₂ ↑.

In essence, the textured surface is to corrode the crystalline silicon wafer through anisotropic etching, and finally form several four side cones on the surface, that is, the "pyramid" structure. After forming this structure, when light is incident on a certain angle of the pyramid slope, the light will reflect another angle slope, forming two or more absorptions, thereby reducing the reflectivity of the silicon wafer surface, that is, the trapping effect. The better the size and uniformity of the "pyramid" structure, the more obvious the trap effect and the lower the surface emissivity of the silicon wafer.

Optionally, in another implementation manner, step 1002 is further included before step 101 above, and step 1032 is further included before step 103 above.

Step 1002, performing texturing treatment on the silicon wafer;

Step 1032 , performing chain pickling and alkali polishing on the silicon wafer after laser grooving.

In this embodiment, the process of polishing first and then polishing can be used to form a polished surface inside the laser groove, which can strengthen the contact between the slurry and the silicon wafer, thereby improving the efficiency of the battery, and avoiding the problem that the slurry cannot contact the bottom of the silicon because the texture is too small and some slurry components are stuck.

In the preparation method of the IBC battery provided in the embodiment of the present invention, the square size after the alkali polishing treatment is 8-12 microns, for example, 8 microns, 10 microns or 12 microns.

Optionally, the above-mentioned alkali polishing treatment is to carry out wet alkali polishing on the raw silicon wafer by adopting KOH+alkaline polishing additive, wherein the mass percentage concentration of KOH is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 300-350s, and the treatment temperature is 72-77°C.

Optionally, the aforementioned chain pickling uses 2% by mass hydrochloric acid and 5% by mass hydrofluoric acid to clean the laser-grooved silicon wafer, and the cleaning time is 30 seconds.

Optionally, the above-mentioned texturing treatment is that the above-mentioned texturing treatment is to carry out groove-type texturing treatment on the original silicon wafer in the form of KOH+texturing additive, wherein the mass percentage concentration of KOH is 1.2%, the texturing additive is EP12V58, the treatment time is 620-670s, and the treatment temperature is 77-82°C.

The present invention also proposes an IBC battery, wherein the battery is prepared by the above-mentioned preparation method of the IBC battery.

The present invention will be described in detail below by way of examples.

Example 1

In parts by mass, the IBC battery silver-aluminum paste a1 consists of 0.4 parts of organic additives, 77 parts of silver powder, 3 parts of aluminum powder, 0.1 part of boron-aluminum alloy powder, 17.7 parts of organic binder and 1.8 parts of glass powder;

Wherein, the above-mentioned organic additive is a silane coupling agent; the silver powder includes micron-sized silver powder with a purity of 3 9s and a mass fraction of 88% and nano-sized silver powder with a purity of 3 9s and a mass fraction of 2%; the aluminum powder includes a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 75% and a D50 of 5 to 6 μm, and a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 25% and a D50 of 9 to 10 μm; the organic binder includes a mass fraction of 9 0% ethyl cellulose-N100 and 10% organic solvent in mass fraction, the organic solvent is composed of benzyl alcohol, diethyl phthalate, terpineol, tributyl citrate, Span 85 and alcohol ester twelve.

(1) Take a 182*182 P-type silicon wafer for alkali polishing treatment, forming a square of 8 to 12 microns on the surface; wherein, the mass percentage concentration of KOH in the alkali polishing treatment is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 320s, and the treatment temperature is 75°C;

(2) After forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, phosphorus doping is carried out to the back polysilicon layer;

(3) Laser groove the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

(4) Take the silicon wafer after laser grooving, use hydrochloric acid with a mass fraction of 2%+hydrofluoric acid with a mass fraction of 5% to carry out chain pickling for 30 seconds, and then perform texturing treatment; wherein, the mass percentage concentration of KOH in the texturing treatment is 1.2%, the texturing additive is EP12V58, the treatment time is 650s, and the treatment temperature is 80°C;

(5) After removing the front polysilicon layer, and forming a passivation film layer, a front anti-reflection film layer, and a back anti-reflection film layer sequentially, print silver-aluminum paste a1 on the first area of the anti-reflection film layer on the back of the silicon wafer, and the projection of the first area is within the p+ doped area; meanwhile, print silver paste on the second area of the back anti-reflection film layer, and the projection of the second area is within the n+ doped area;

(6) The above-mentioned P-type silicon wafer was sintered at high temperature to produce an IBC battery, and the peak temperature of sintering was 766° C. to produce an IBC battery.

After sintering, the electrical data tested are: open circuit voltage 724.5mV, photoelectric conversion efficiency 25.155%.

Example 2

In terms of parts by mass, the IBC battery silver-aluminum paste a2 consists of 0.6 parts of organic additives, 65 parts of silver powder, 5 parts of aluminum powder, 0.05 parts of boron-aluminum alloy powder, 28.35 parts of organic binder and 1 part of glass powder;

Wherein, the above-mentioned organic additive is a silane coupling agent; the silver powder includes a micron-sized silver powder with a purity of 3 9s and a mass fraction of 94 and a nano-sized silver powder with a purity of 3 9s and a mass fraction of 6%; the aluminum powder includes a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 80% and a D50 of 5 to 6 μm, and a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 20% and a D50 of 9 to 10 μm; the organic binder includes a mass fraction of 90 % of ethyl cellulose-N100 and mass fraction of 10% organic solvent, the organic solvent is composed of benzyl alcohol, diethyl phthalate, terpineol, tributyl citrate, Span 85 and alcohol ester twelve.

(1) Take a 182*182 P-type silicon wafer for alkali polishing treatment, forming a square of 8 to 12 microns on the surface; wherein, the mass percentage concentration of KOH in the alkali polishing treatment is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 320s, and the treatment temperature is 75°C;

(2) After forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, phosphorus doping is carried out to the back polysilicon layer;

(3) Laser groove the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

(4) Take the silicon wafer after laser grooving, use hydrochloric acid with a mass fraction of 2%+hydrofluoric acid with a mass fraction of 5% to carry out chain pickling for 30 seconds, and then perform texturing treatment; wherein, the mass percentage concentration of KOH in the texturing treatment is 1.2%, the texturing additive is EP12V58, the treatment time is 650s, and the treatment temperature is 80°C;

(5) After removing the front polysilicon layer, and forming a passivation film layer, a front anti-reflection film layer, and a back anti-reflection film layer sequentially, the silver-aluminum paste a2 is printed in the first area of the anti-reflection film layer on the back side of the silicon wafer, and the projection of the first area is within the p+ doped area; meanwhile, the silver paste is printed in the second area of the back anti-reflection film layer, and the projection of the second area is within the n+ doped area;

(6) The above-mentioned P-type silicon wafer was sintered at high temperature to produce an IBC battery, and the peak temperature of sintering was 772° C. to produce an IBC battery.

After sintering, the electrical data tested are: open circuit voltage 725.5mV, photoelectric conversion efficiency 25.185%.

Example 3

In parts by mass, the IBC battery silver-aluminum paste a3 consists of 0.5 parts of organic additives, 75 parts of silver powder, 4 parts of aluminum powder, 0.75 parts of boron-aluminum alloy powder, 18.25 parts of organic binder and 1.5 parts of glass powder;

Wherein, the above-mentioned organic additive is a silane coupling agent; the silver powder includes micron-sized silver powder with a purity of 3 9s and a mass fraction of 90 and nano-sized silver powder with a purity of 3 9s and a mass fraction of 10%; the aluminum powder includes a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 78% and a D50 of 5 to 6 μm, and a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 22% and a D50 of 9 to 10 μm; the organic binder includes a mass fraction of 9 0% ethyl cellulose-N100 and 10% organic solvent in mass fraction, the organic solvent is composed of benzyl alcohol, diethyl phthalate, terpineol, tributyl citrate, Span 85 and alcohol ester twelve.

(1) Take a 182*182 P-type silicon wafer for alkali polishing treatment, forming a square of 8 to 12 microns on the surface; wherein, the mass percentage concentration of KOH in the alkali polishing treatment is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 320s, and the treatment temperature is 75°C;

(2) After forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, phosphorus doping is carried out to the back polysilicon layer;

(3) Laser groove the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

(4) Take the silicon wafer after laser grooving, use hydrochloric acid with a mass fraction of 2%+hydrofluoric acid with a mass fraction of 5% to carry out chain pickling for 30 seconds, and then perform texturing treatment; wherein, the mass percentage concentration of KOH in the texturing treatment is 1.2%, the texturing additive is EP12V58, the treatment time is 650s, and the treatment temperature is 80°C;

(5) After removing the front polysilicon layer, and forming a passivation film layer, a front anti-reflection film layer, and a back anti-reflection film layer successively, the silver-aluminum paste a3 is printed in the first area of the anti-reflection film layer on the back side of the silicon wafer, and the projection of the first area is within the p+ doped area; meanwhile, the silver paste is printed in the second area of the back anti-reflection film layer, and the projection of the second area is within the n+ doped area;

(6) The above-mentioned P-type silicon wafer was sintered at high temperature to produce an IBC battery, and the peak temperature of sintering was 774° C. to produce an IBC battery.

After sintering, the electrical data tested are: open circuit voltage 726.1mV, photoelectric conversion efficiency 25.208%.

Example 4

In terms of parts by mass, the IBC battery silver-aluminum paste a4 consists of 0.4 parts of organic additives, 65 parts of silver powder, 3 parts of aluminum powder, 0.05 parts of boron aluminum alloy powder, 30.55 parts of organic binder and 1 part of glass powder;

Wherein, the above-mentioned organic additive is a silane coupling agent; the silver powder includes a micron-sized silver powder with a purity of 3 9s and a mass fraction of 94 and a nano-sized silver powder with a purity of 3 9s and a mass fraction of 6%; the aluminum powder includes a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 80% and a D50 of 5 to 6 μm, and a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 20% and a D50 of 9 to 10 μm; the organic binder includes a mass fraction of 90 % of ethyl cellulose-N100 and mass fraction of 10% organic solvent, the organic solvent is composed of benzyl alcohol, diethyl phthalate, terpineol, tributyl citrate, Span 85 and alcohol ester twelve.

(1) Take a 182*182 P-type silicon wafer for alkali polishing treatment, forming a square of 8 to 12 microns on the surface; wherein, the mass percentage concentration of KOH in the alkali polishing treatment is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 320s, and the treatment temperature is 75°C;

(2) After forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, phosphorus doping is carried out to the back polysilicon layer;

(3) Laser groove the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

(4) Take the silicon wafer after laser grooving, use hydrochloric acid with a mass fraction of 2%+hydrofluoric acid with a mass fraction of 5% to carry out chain pickling for 30 seconds, and then perform texturing treatment; wherein, the mass percentage concentration of KOH in the texturing treatment is 1.2%, the texturing additive is EP12V58, the treatment time is 650s, and the treatment temperature is 80°C;

(5) After removing the front polysilicon layer, and forming a passivation film layer, a front anti-reflection film layer, and a back anti-reflection film layer sequentially, print silver-aluminum paste a4 on the first area of the anti-reflection film layer on the back side of the silicon wafer, and the projection of the first area is within the p+ doped area; at the same time, print silver paste in the second area of the back anti-reflection film layer, and the projection of the second area is within the n+ doped area;

(6) The above-mentioned P-type silicon wafer is sintered at high temperature to produce an IBC battery, and the peak temperature of sintering is 775° C. to produce an IBC battery.

After sintering, the electrical data tested are: open circuit voltage 726.8mV, photoelectric conversion efficiency 25.218%.

Comparative example 1

In parts by mass, the IBC battery silver-aluminum paste a2 consists of 0.6 parts of organic additives, 70 parts of aluminum powder, 0.05 parts of boron-aluminum alloy powder, 28.35 parts of organic binder and 1 part of glass powder;

Wherein, the above-mentioned organic additive is a silane coupling agent; the aluminum powder includes a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 80% and a D50 of 5-6 μm, and a micron-sized aluminum powder with a purity of 3 9s and a mass fraction of 20% and a D50 of 9-10 μm; the organic binder includes ethyl cellulose-N100 with a mass fraction of 90% and an organic solvent with a mass fraction of 10%. The organic solvent is composed of benzyl alcohol, diethyl phthalate, terpineol , tributyl citrate, Span 85 and alcohol ester twelve.

(1) Take a 182*182 P-type silicon wafer for alkali polishing treatment, forming a square of 8 to 12 microns on the surface; wherein, the mass percentage concentration of KOH in the alkali polishing treatment is 1.5%, the alkali polishing additive is Topband EP12V88, the treatment time is 320s, and the treatment temperature is 75°C;

(2) After forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, phosphorus doping is carried out to the back polysilicon layer;

(3) Laser groove the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions;

(4) Take the silicon wafer after laser grooving, use hydrochloric acid with a mass fraction of 2%+hydrofluoric acid with a mass fraction of 5% to carry out chain pickling for 30 seconds, and then perform texturing treatment; wherein, the mass percentage concentration of KOH in the texturing treatment is 1.2%, the texturing additive is EP12V58, the treatment time is 650s, and the treatment temperature is 80°C;

(5) After removing the front polysilicon layer, and forming a passivation film layer, a front anti-reflection film layer, and a back anti-reflection film layer successively, carry out laser slotting to the p+ doped area, and print the above-mentioned printing silver-aluminum paste b1 in the first area of the anti-reflection film layer on the back side of the silicon chip in the laser groove conducting with the p+ doped area.

(6) The above-mentioned P-type silicon wafer is sintered at high temperature to produce an IBC battery, and the peak temperature of sintering is 776° C. to produce an IBC battery.

After sintering, the electrical data tested are: open circuit voltage 718.2mV, photoelectric conversion efficiency 24.92%.

Comparing Examples 1 to 4 with Comparative Example 1, it can be seen that the P+ emitter is formed by using the aluminum paste doped with silver, and the positive grid line can be formed without laser grooving, and the recombination rate and recombination degree of the battery will also be greatly improved. The efficiency of the battery is increased by 0.20%, and the opening voltage is increased by 5mv.

In summary, in this embodiment, by adding silver powder to aluminum paste, not only can it be replaced by the P+in the P+, but because the silver powder has a good burning nature, it has better contact with the battery tablet itself. Raising 0.3 to 0.5 %, it solves the problem that the existing IBC battery aluminum paste is prone to the problem of poor battery efficiency when printing into a positive grid line.

Having described preferred embodiments of embodiments of the present invention, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, the claims are intended to be interpreted to include the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

An IBC battery provided by the present invention and its preparation method have been introduced in detail above. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above examples is only used to help understand the method of the present invention and its core idea. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and application range. In summary, the content of this specification should not be understood as limiting the present invention.

Claims (10)

1. A preparation method for an IBC battery, characterized in that, comprising: After sequentially forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer, phosphorus doping is performed on the back polysilicon layer; Laser grooves on the back of the phosphorus-doped P-type silicon wafer to form interdigitated n+ doped regions and p+ doped regions; After laser grooving, a passivation film layer and an anti-reflection film layer are formed on both sides of the silicon wafer; Print silver-aluminum paste on the first area of the anti-reflection film layer on the back of the silicon wafer, and print silver paste on the second area of the anti-reflection film layer on the back of the silicon wafer; the projection of the first area is within the range of the p+ doped area, and the projection of the second area is within the range of the n+ doped area; The P-type silicon wafer printed with silver-aluminum paste in the first region and silver paste in the second region is sintered at high temperature to produce an IBC battery. 2. The preparation method according to claim 1, characterized in that, the components constituting the silver-aluminum paste include organic additives, silver powder, aluminum powder, boron-aluminum alloy powder, organic binder and glass powder. 3. The preparation method according to claim 2, wherein, in the silver-aluminum paste, the mass percentage of the organic additive is 0.4-0.6%; the mass percentage of the silver powder is 65-75%; the mass percentage of the aluminum powder is 3-5%; the mass percentage of the boron aluminum alloy powder is 0.05-0.1%; the mass percentage of the organic binder is 17.5-30.55%; the mass percentage of the glass powder is 1-1.8%. 4. The preparation method according to claim 3, characterized in that, the aluminum powder includes a mass fraction of 75-80% and a D50 of 5-6 μm micron-sized aluminum powder, and a mass fraction of 20-25% and a D50 of 9-10 μm micron-sized aluminum powder; the silver powder includes a mass fraction of 75-80% of a micron-sized silver powder and a mass fraction of nano-sized silver powder. 5. The preparation method according to claim 2, wherein the organic additive comprises at least one of silane coupling agent, lauryl phosphate, silicone oil, and dibasic acid ester. 6. The preparation method according to claim 1, wherein the passivation layer is an aluminum oxide layer, and the antireflection film layer is a silicon nitride layer. 7. The preparation method according to claim 1, characterized in that, before forming a silicon oxide layer and a polysilicon layer on the back of the P-type silicon wafer in sequence, the method further comprises: Carry out alkali polishing treatment to described silicon chip; Before forming a passivation film layer and an anti-reflection film layer on both sides of the silicon wafer, the method also includes: Carry out chain pickling and texturing treatment on silicon wafers after laser grooving. 8. The preparation method according to claim 1, characterized in that, before forming a silicon oxide layer and a polysilicon layer in turn on the back of the P-type silicon wafer, the method further comprises: Carry out texture processing to described silicon chip; Before forming a passivation film layer and an anti-reflection film layer on both sides of the silicon wafer, the method also includes: Perform chain pickling and alkali polishing on silicon wafers after laser grooving. 9. The preparation method according to claim 7 or 8, characterized in that the square size after alkali polishing is 8-12 microns. 10. An IBC battery, characterized in that it is prepared by the method described in claims 1-9.