Manufacturing method of half-piece TOPCON battery and TOPCON battery

Abstract

The invention provides a manufacturing method of a half-piece TOPCON battery and the TOPCON battery, and belongs to the technical field of solar battery manufacturing, and the manufacturing method comprises the following steps: carrying out boron diffusion on the front surface of a whole battery piece; removing and cleaning the back surface of the whole battery piece around diffusion; depositing an oxide layer and polycrystalline silicon of the whole battery piece; carrying out phosphorus doping on the back surface of the whole battery piece; the whole battery piece is cut into two halves through laser to form two half battery pieces; winding plating removal and glass removal cleaning are carried out on the front surface of the half battery piece; passivating the front surface and the back surface of the half battery piece; screen-printing an electrode on a half battery piece and sintering; and testing the half battery piece, and welding the half battery piece which is qualified in the test to obtain the TOPCON battery. According to the method, the whole piece of laser half-piece cutting is carried out after the back phosphorus doping process, the damage generated by laser cutting of the half-piece can be etched in the front winding plating removal and glass removal cleaning process, the edge damage is further passivated in the front and back passivation process, the battery cutting loss and the module packaging loss are reduced to the maximum extent, and the module income is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cell manufacturing, and in particular relates to a manufacturing method of a half-cell TOPCON cell and a TOPCON cell manufactured based on the same. Background Art

[0002] TOPCON technology, namely Tunnel Oxide Passivated Contact technology, is a new type of passivation contact technology, which uses an ultra-thin oxide layer and doped thin film silicon for passivation on the surface of the battery. At the same time, ultra-thin silicon oxide reduces the surface state and maintains a low tunneling resistance, and doped thin film silicon provides field passivation and selectively transmits carriers, forming a good passivation contact with the silicon substrate. TOPCON cells are the current development trend of high-efficiency N-type cells.

[0003] In recent years, due to the obvious advantages of half-cell technology, the manufacturing cost of components has been steadily declining, so its production capacity has expanded rapidly. In layman's terms, half-cell technology is a technology that cuts a cell (182mm×182mm) into two halves and connects them in a series + parallel structure after cutting. Components using half-cell technology are different from common photovoltaic components (with 60 or 72 complete cells), but have become 120 or 144 half-cell cells, which can reduce the current passing through each main grid to about 1 / 2 of the original and reduce internal losses to about 1 / 4, thereby increasing the power of photovoltaic components, but at the same time maintaining the same design and size as conventional components.

[0004] At present, the process of TOPCON battery preparation and processing is to carry out alkali texturing, front boron diffusion, back winding diffusion removal and cleaning, ultra-thin oxide layer and polysilicon deposition, back phosphorus doping, front de-coating and glass removal cleaning, front and back passivation, screen printing electrodes and sintering for the whole battery cell. After that, the efficiency test is carried out, and the batteries with consistent test efficiency are transported to the assembly workshop for assembly processing, laser cutting of half pieces, and then the half pieces are welded to form a battery string, and then laid, laminated and framed according to the assembly process, and the photovoltaic cell is completed.

[0005] Laser cutting of half a cell will inevitably damage the cut surface of the cell, which can easily lead to defects in the cross section, thereby reducing cell efficiency and increasing the packaging loss from the cell to the module.

[0006] In order to reduce the impact of the above-mentioned cutting damage on the efficiency of the module, a passivation step is added after the laser cell half-cutting to reduce the impact of the cutting edge. The specific steps are as follows:

[0007] After the whole cell is processed, during the processing of photovoltaic modules, that is, after the cell is cut into half pieces (before welding), the aluminum oxide passivation edge technology is added to passivate the cross section. The cross section is repaired by combining aluminum oxide chemical passivation and field passivation to improve the cell conversion efficiency. Usually, the power of photovoltaic modules can be increased by about 3W (144 half-cell modules). The reaction gases of aluminum oxide passivation edge technology are trimethylaluminum (TMA) and water vapor (H2O) / ozone (O3). Aluminum oxide film is formed on the cut surface of stacked silicon wafers by atomic layer deposition. The film thickness is between 5nm-50nm, which passivates impurities and recombination centers introduced by cutting and improves battery performance.

[0008] The above steps involve cutting and edge passivation after the entire battery is prepared. Although this can increase the module power, it increases the investment in alumina equipment and the module packaging cost. In addition, after cutting and edge passivation, the efficiency of the two halves may be inconsistent, which can easily cause module mismatch, affect module power, and reduce module revenue. Summary of the invention

[0009] The embodiments of the present invention provide a method for manufacturing a half-cell TOPCON battery and a TOPCON battery manufactured based on the method, aiming to solve the problem of defects in the battery cell caused by laser cutting, resulting in reduced battery efficiency and packaging loss.

[0010] In the first aspect, in order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a method for manufacturing a half-cell TOPCON battery, comprising:

[0011] Boron diffusion on the front side of the whole cell;

[0012] The back of the entire cell is cleaned by diffusion removal;

[0013] Deposition of oxide layer and polysilicon for the entire cell;

[0014] Phosphorus doping on the back of the entire cell;

[0015] The whole cell is laser cut into two halves, becoming two half-cells;

[0016] Remove the plating and glass cleaning on the front side of half a cell;

[0017] Passivation of the front and back sides of half-cell cells;

[0018] Screen-print electrodes on half a cell and sinter them;

[0019] Half-cell battery cell test, the qualified half-cell battery cell is welded together to obtain TOPCON battery.

[0020] In a first aspect, in an achievable manner, the front side of the half-cell is de-plated and cleaned by removing the glass, using chain cleaning and tank cleaning in sequence.

[0021] In a first aspect, in an achievable manner, the chain cleaning process includes: exposing a half-cell non-phosphorus diffusion surface downward to a chemical reagent, and using an acidic reagent to remove an oxide layer on the lower surface and edge of the half-cell.

[0022] In a first aspect, in one achievable manner, the acidic reagent is hydrofluoric acid at room temperature and a concentration of 1%-10%.

[0023] In a first aspect, in one achievable manner, the normal temperature of the chain cleaning process is 20°C-25°C.

[0024] In a first aspect, in an achievable manner, the trough cleaning process includes: placing a half-cell in a flower basket and immersing it in a trough device, etching the non-phosphorus diffusion surface and edge of the half-cell with a low-concentration alkaline solution, and cleaning the surface poly-Si and the dangling bonds formed during the cutting process.

[0025] In a first aspect, in an achievable manner, the temperature of the low-concentration alkali solution is controlled at 40° C.-70° C., and the concentration is 0.1%-5%.

[0026] In a first aspect, in one achievable manner, the temperature of the low-concentration alkali solution is controlled at 50°C-60°C.

[0027] In a first aspect, in one achievable manner, the front and back sides of the half-cell are passivated, and the thickness of the front passivation film and the back passivation film are both 3-50 nm.

[0028] In a second aspect, the present invention also provides a TOPCON battery, which is manufactured based on the manufacturing method of the half-cut cell, and includes a substrate, wherein a back side of the substrate is provided with a back tunneling oxide layer, a back side polysilicon layer, a back side passivation layer and a back side metal electrode in sequence, and a front side of the substrate is provided with a front tunneling oxide layer, a front side polysilicon layer, a front side passivation layer and a front side metal electrode in sequence.

[0029] Compared with the prior art, the method for manufacturing a half-cell TOPCON cell and the TOPCON cell provided by the present invention have the following beneficial effects: the present invention adds a whole-cell laser cutting half-cell technology after the phosphorus doping process on the back side of the TOPCon cell. Compared with the original process of cutting the whole cell into half-cells in a photovoltaic module workshop after the whole cell processing is completed, the equipment investment is not increased, and the damage caused by the laser cutting of the half-cell can be etched on the edge during the front-side de-plating and de-glassing cleaning process by appropriately adjusting the cleaning process to clean off the dangling bonds formed on the silicon wafer surface during the cutting process, and the edge damage is further passivated by optimizing the alumina passivation process during the front and back passivation processes. There is no need to add additional alumina edge passivation equipment, and the battery workshop cost is not significantly increased. The battery cutting loss and component packaging loss can be minimized to maximize the reduction, thereby improving the profit of the component. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the structure of a TOPCON battery provided in an embodiment of the present invention;

[0031] In the figure: 1. substrate; 2. back tunneling oxide layer; 3. back polysilicon layer; 4. back passivation layer; 5. back metal electrode; 6. front tunneling oxide layer; 7. front polysilicon layer; 8. front passivation layer; 9. front metal electrode. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Since the half-cell technology reduces the internal current and line resistance, the internal loss consumed in the internal loop is reduced. The power loss is proportional to the current. Half the current and one-quarter the resistance allow the half-cell module to reduce the power loss by 4 times, which correspondingly increases the output power and power generation. Therefore, it has become the mainstream technology in module packaging technology, and the half-cell module technology requires the support of half-cell batteries. The industry usually manufactures complete battery cells, and uses half-cell patterns when printing patterns. Before welding in the component workshop, the whole cell, such as 182×182mm in size, is cut into 182×91mm×2 pieces by laser, and then serially welded. However, cutting losses are usually caused during the battery cutting process. Even if a non-destructive cutting method is used, the battery efficiency will decrease by about 0.2-0.3%. The technical solution provided by the present invention can improve this problem.

[0034] The manufacturing method of the half-cell TOPCON battery provided by the present invention is now described.

[0035] Embodiment 1:

[0036] The method for manufacturing the half-cell TOPCON battery comprises:

[0037] Boron diffusion on the front side of the whole cell;

[0038] The back of the entire cell is cleaned by diffusion removal;

[0039] Deposition of oxide layer and polysilicon for the entire cell;

[0040] Phosphorus doping on the back of the entire cell;

[0041] The whole cell is laser cut into two halves, becoming two half-cells;

[0042] Remove the plating and glass cleaning on the front side of half a cell;

[0043] Passivation of the front and back sides of half-cell cells;

[0044] Screen-print electrodes on half a cell and sinter them;

[0045] Half-cell battery cell test, the qualified half-cell battery cell is welded together to obtain TOPCON battery.

[0046] Compared with the prior art, the method for manufacturing a half-cell TOPCON cell provided by the present invention has the following beneficial effects: the present invention adds a whole-cell laser cutting half-cell technology after the phosphorus doping process on the back side of the TOPCON cell. Compared with the original process of cutting the whole cell into half-cells in a photovoltaic module workshop after the whole cell processing is completed, the equipment investment is not increased, and the damage caused by the laser cutting of the half-cell can be etched on the edge during the front-side de-plating and de-glassing cleaning process by appropriately adjusting the cleaning process to clean off the dangling bonds formed on the silicon wafer surface during the cutting process, and the edge damage is further passivated by optimizing the alumina passivation process during the front and back passivation processes. There is no need to add additional alumina edge passivation equipment, and the cost of the cell workshop is not significantly increased. The cell cutting loss and the component packaging loss can be minimized to maximize the reduction of the component revenue.

[0047] Embodiment 2:

[0048] Half-cell preparation is carried out directly during battery processing, and the process is as follows:

[0049] Step 1: Alkali velveting (whole piece of tooling);

[0050] Step 2: Front boron diffusion (whole piece tooling);

[0051] Step 3: Back side diffusion removal and cleaning (whole piece tooling);

[0052] Step 4: Ultra-thin oxide layer and polysilicon deposition (whole piece tooling);

[0053] Step 5: Back side phosphorus doping (whole piece tooling);

[0054] Step 6: Laser cutting the whole piece into half pieces;

[0055] Step 7: Remove the plating and glass cleaning on the front side (half-piece tooling);

[0056] Step 8: front and back passivation, including aluminum oxide passivation and silicon nitride passivation process (half-wafer tooling);

[0057] Step 9: Screen printing electrodes and sintering (half-piece tooling);

[0058] Step 10: Test half of the cell and transfer the half cell to the assembly workshop for direct welding process.

[0059] In the seventh step of the process adjustment, the cleaning solution etching conditions may be appropriately increased, as follows: the cleaning step generally includes chain + tank cleaning.

[0060] Chain cleaning, the non-phosphorus diffusion surface is exposed to the chemical reagent downward, and an acidic reagent is used to remove the oxide layer on the lower surface and edge of the silicon wafer. Usually hydrofluoric acid is used at room temperature with a concentration of 1%-10%.

[0061] Tank cleaning: Place the silicon wafer in a basket and immerse it in a tank device. Use low-concentration alkali solution to etch the non-phosphorus diffusion surface and edge of the silicon wafer, and clean the surface poly-Si and the hanging bonds formed during the cutting process. The phosphorus diffusion surface of the silicon wafer will not be etched away under the protection of phosphorus silicon glass. The alkali solution temperature is controlled at 40-70℃, and the concentration is 0.1%-5%.

[0062] The eighth step of the process adjustment is achieved by extending the process time or increasing the process gas concentration. The thickness of the aluminum oxide passivation film layer of atomic layer deposition is increased by increasing the number of process cycles. The thickness of the passivation film is usually controlled to be 3-50nm, so as to achieve the passivation effect on defective positions such as dangling bonds at the edge of laser etching.

[0063] The present invention also provides a TOPCON battery, see Figure 1 As shown, the manufacturing method of the half-cut TOPCON battery includes a substrate 1, a back side tunneling oxide layer 2, a back side polysilicon layer 3, a back side passivation layer 4 and a back side metal electrode 5 are sequentially arranged on the back side of the substrate 1, and a front side tunneling oxide layer 6, a front side polysilicon layer 7, a front side passivation layer 8 and a front side metal electrode 9 are sequentially arranged on the front side of the substrate 1.

[0064] The TOPCON cell manufactured by the manufacturing method provided by the present invention can minimize cell cutting loss and component packaging loss without significantly increasing production costs, thereby increasing the profit of photovoltaic components.

[0065] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a half-cell TOPCON battery, characterized in that: include: Boron diffusion on the front side of the whole cell; The back of the entire cell is cleaned by diffusion removal; Deposition of oxide layer and polysilicon for the entire cell; Phosphorus doping on the back of the entire cell; The whole cell is laser cut into two halves, becoming two half-cells; Remove the plating and glass cleaning on the front side of half a cell; Passivation of the front and back sides of half-cell cells; Screen-print electrodes on half of the cell and sinter; Half-cell battery cell test, the qualified half-cell battery cell is welded together to obtain TOPCON battery.

2. The method for manufacturing a half-cell TOPCON battery according to claim 1, characterized in that: The front side of the half-cell is de-plated and cleaned by removing the glass, using chain cleaning and tank cleaning in sequence.

3. The method for manufacturing a half-cell TOPCON battery according to claim 2, characterized in that: The chain cleaning process includes: placing the non-phosphorus diffusion surface of the half-cell in contact with a chemical reagent downward, and using an acidic reagent to remove the oxide layer on the lower surface and edge of the half-cell.

4. The method for manufacturing a half-cell TOPCON battery according to claim 3, characterized in that: The acidic reagent is hydrofluoric acid at room temperature and a concentration of 1%-10%.

5. The method for manufacturing a half-cell TOPCON battery according to claim 4, characterized in that: The normal temperature of the chain cleaning process is 20°C-25°C.

6. The method for manufacturing a half-cell TOPCON battery according to claim 2, characterized in that: The tank cleaning process includes: placing a half-cell in a flower basket and immersing it in a tank device, etching the non-phosphorus diffusion surface and edge of the half-cell with a low-concentration alkali solution, and cleaning the surface poly-Si and the dangling bonds formed during the cutting process.

7. The method for manufacturing a half-cell TOPCON battery according to claim 6, characterized in that: The temperature of the low-concentration alkali solution is controlled at 40° C.-70° C., and the concentration is 0.1%-5%.

8. The method for manufacturing a half-cell TOPCON battery according to claim 7, characterized in that: The temperature of the low concentration alkali solution is controlled at 50°C-60°C.

9. The method for manufacturing a half-cell TOPCON battery according to claim 1, characterized in that: The front and back sides of the half-cell are passivated, and the thickness of the front passivation film and the back passivation film are both 3-50 nm.

10. A TOPCON battery, manufactured based on the manufacturing method of a half-cell TOPCON battery according to any one of claims 1 to 9, characterized in that: The invention comprises a substrate (1), wherein a back side tunneling oxide layer (2), a back side polysilicon layer (3), a back side passivation layer (4) and a back side metal electrode (5) are sequentially arranged on the back side of the substrate (1), and a front side tunneling oxide layer (6), a front side polysilicon layer (7), a front side passivation layer (8) and a front side metal electrode (9) are sequentially arranged on the front side of the substrate (1).

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