PERC battery and preparation method thereof

Abstract

The embodiment of the invention provides a PERC battery and a preparation method thereof, and the preparation method of the PERC battery provided by the embodiment of the invention comprises the steps: carrying out the scribing of a sintered PERC battery piece, then carrying out the electric injection, activating atoms in a silicon nitride passivation film through the electric injection principle, and controlling the valence state of H atoms through the introduction of a current. The N + emitter and the P substrate are combined with the composite center to form a non-composite center, and passivation repair of a scribing wound is realized, so that the problem that the efficiency loss is too large after a PERC battery is manufactured by an existing method is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystalline silicon solar cell manufacturing, and in particular to a PERC cell and a preparation method thereof. Background Art

[0002] Due to the passivation of the back surface dielectric film and the use of local metal contact, the surface recombination rate is greatly reduced, while the light reflection of the back surface is improved, making the PERC cell have a higher photoelectric conversion efficiency.

[0003] Currently, the manufacturing process of PERC cells includes texturing and cleaning, high-temperature diffusion, etching and polishing, back-side aluminum oxide film deposition, front-side silicon nitride film deposition, back-side laser grooving, printing and sintering, electrical injection processing, and dicing processing.

[0004] Among them, the dicing process can divide the battery cells into smaller and uniform battery cell groups, thereby improving the stability and reliability of the battery cells, but it also causes the efficiency of the half-sliced ​​PERC battery prepared by the above process to lose about 0.3%. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a PERC battery and a preparation method thereof, so as to solve the problem of excessive efficiency loss after slicing of PERC batteries made by the existing method.

[0006] In order to solve the above problems, the present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for preparing a PERC battery, which comprises:

[0008] Slice the PERC cell after sintering to form the electrode grid lines into half cells;

[0009] The battery half-cell is electrically injected to obtain a PERC battery.

[0010] Furthermore, in the method for preparing the PERC cell, the PERC cell slice after sintering to form the electrode grid lines is diced into cell halves, comprising:

[0011] The PERC cell is diced into cell halves using a laser.

[0012] Furthermore, in the method for preparing the PERC cell, the light source of the laser is green light.

[0013] Furthermore, in the method for preparing the PERC battery, in the scribing process, the laser power is 50 to 70 W and the frequency is 1000 to 1500 Hz.

[0014] Furthermore, in the method for preparing the PERC battery, the irradiation time of the laser is 2 to 10 picoseconds.

[0015] Furthermore, in the method for preparing the PERC cell, the battery half-cell is electrically injected, comprising:

[0016] The battery half-cell is electrically injected at a temperature of 220-280° C. and a current of 0-10A.

[0017] Furthermore, in the method for preparing the PERC cell, the battery half-cell is electrically injected, comprising:

[0018] The battery half-cell is electrically injected at a temperature of 240-250° C. and a current of 5-8A.

[0019] Furthermore, in the method for preparing the PERC battery, the time of the electricity injection is 2200 to 3000 seconds.

[0020] Furthermore, in the method for preparing the PERC cell, the battery half-cell is electrically injected, comprising:

[0021] The battery half-cell is sequentially injected with electricity through a plurality of cavities, and the total duration of the battery half-cell being injected with electricity in each of the cavities is 2200 to 3000 seconds.

[0022] The present invention also provides a PERC battery, which is prepared by the above method.

[0023] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0024] In an embodiment of the present invention, a method for preparing a PERC cell is provided, wherein the PERC cell slice after sintering to form the electrode grid lines is sliced ​​into cell halves, and then the cell halves are electrically injected to prepare the PERC cell. The sintered PERC cell slice is first sliced ​​and then electrically injected, and the atoms in the silicon nitride passivation film can be activated by the principle of electrical injection, and the valence state of the H atoms can be controlled by current introduction, so that they are combined with the recombination center at the N+ emitter and the P substrate to form a non-recombination center, thereby achieving passivation repair of the slicing wound, thereby effectively solving the problem of excessive efficiency loss after slicing of PERC cells made by the existing method.

[0025] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a method for preparing a PERC battery provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The applicant of the present invention has found that the manufacturing process of conventional PERC cells includes processes such as texturing and cleaning, high-temperature diffusion, etching and polishing, deposition of aluminum oxide film on the back side, deposition of silicon nitride film on the front side, laser grooving on the back side, printing and sintering, electrical injection, and scribing. Among them, the scribing process can divide the cell into smaller and more uniform cell groups, thereby improving the stability and reliability of the cell; however, the scribing process will cause heat loss, crack loss, and passivation defect loss at the cut surface to the cell, ultimately resulting in an efficiency loss of about 0.3% for the half-cut PERC cell prepared by the above process.

[0029] For example, if the efficiency of a 182*183.75 PERC cell after sintering is 23.5%, the efficiency loss after dicing is approximately 0.2% to 0.3%, which translates to a power loss of approximately 0.066W to 0.099W. For example, if a large assembly line has a daily production capacity of approximately 4,800 72-panel modules, the total power loss is between 22,809.6W and 34,214.4W, which will bring significant economic losses to production.

[0030] In order to solve the above problems, the present invention provides a method for preparing a PERC battery, wherein: Figure 1 As shown, it includes steps 101 to 102:

[0031] Step 101, dicing the PERC cell after sintering to form electrode grid lines into cell halves;

[0032] Step 102: inject electricity into the half cell to obtain a PERC cell.

[0033] In the embodiment of the present invention, the PERC cell slice after sintering to form the electrode grid lines is sliced ​​into half-cell slices, and then the half-cell slices are electrically injected to produce a PERC cell. The sintered PERC cell slice is first sliced ​​and then electrically injected. The principle of electrical injection can be used to activate the atoms in the silicon nitride passivation film, and the valence state of the H atoms is controlled by current introduction, so that they are combined with the recombination center at the N+ emitter and the P substrate to form a non-recombination center, thereby achieving passivation repair of the slicing wound, so that the total power of the cell slice is not lost before and after slicing, thereby effectively solving the problem of excessive efficiency loss after slicing of PERC cells made by the existing method.

[0034] In the above step 101, a single crystal silicon wafer is taken and double-sided texturing and high-temperature phosphorus diffusion treatment are performed in sequence, and then the phosphorus silicon glass on the surface of the silicon wafer is removed and then alkali polishing is performed, and then a passivation film layer and an anti-reflection layer are formed on the surface of the silicon wafer, and then the slurry is printed and sintered to form electrode grid lines, and the above-mentioned PERC cell can be obtained.

[0035] Among them, the specific process of double-sided texturing treatment is to use KOH and texturing additives for wet texturing treatment, wherein, by volume, the texturing liquid includes 7.5 parts of 45% concentrated KOH, 2.5 parts of texturing additive TB22V21 and 490 parts of pure water, the treatment time is 420s, and the treatment temperature is 82°C.

[0036] In the phosphorus diffusion treatment, the phosphorus is first deposited for 8 to 12 minutes at a temperature of 870 to 920°C, a POCl3 flow rate of 80 to 150 sccm / min, an oxygen flow rate of 500 to 800 sccm / min, a nitrogen flow rate of 1200 to 2000 sccm / min, and a pressure of 150 to 200 mbar. Then the silicon wafer is heated to 920 to 1000°C and treated for 40 to 80 minutes at a pressure of 800 mbar and an oxygen flow rate of 8000 to 15000 sccm / min to obtain a surface doping concentration of 2E18 to 5E18 / cm 3 n+ doped region.

[0037] The sheet resistance after phosphorus doping is 30-40Ω / sq, and the junction depth of ECV is 0.5-1.5μm. For example, the sheet resistance after phosphorus doping is 35Ω / sq, and the junction depth of ECV is 0.9μm.

[0038] The phosphorus-doped silicon wafer is cleaned with 2-5% hydrochloric acid and 2-5% hydrofluoric acid to remove the phosphorus-silicate glass on the surface of the silicon wafer.

[0039] Among them, KOH and alkali polishing additives are used for alkali polishing treatment, wherein, by volume, the alkali polishing solution includes 18 parts of concentrated KOH, 2 parts of alkali polishing additive BP65 and 420 parts of pure water, the treatment time is 280s, and the treatment temperature is 80°C.

[0040] Among them, the 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 layer is formed, an anti-reflection film layer is first plated on the front of the battery, and then on the back, to further enhance the passivation effect of the battery cell.

[0041] Optionally, the passivation layer is an aluminum oxide film layer, that is, the aluminum oxide film layer is plated on the entire front surface and the entire back surface as the passivation layer.

[0042] Optionally, the anti-reflection film layer is a silicon nitride layer, that is, the anti-reflection film is formed by coating the entire front surface and the entire back surface with a silicon nitride layer; wherein the anti-reflection film includes multiple layers of silicon nitride layers, which can further enhance the anti-reflection effect.

[0043] Optionally, in one embodiment, the passivation film layer includes aluminum oxide, and has a thickness of 6 to 10 nm, for example, a range of one or any two of 6 nm, 8 nm, and 10 nm.

[0044] Optionally, in one embodiment, the anti-reflection layer includes silicon nitride, and has a thickness of 70 to 95 nm, for example, a range of one or any two of 70 nm, 75 nm, 80 nm, and 85 nm.

[0045] Optionally, in a specific embodiment, the anti-reflection layer includes a front anti-reflection layer and a back anti-reflection layer; wherein the thickness of the front anti-reflection layer is 70 to 85 nm and the refractive index is 2.0 to 2.05, for example, it can be one of 70 nm, 75 nm, 80 nm, 85 nm or any two of the range values; the thickness of the back anti-reflection layer is 75 to 95 nm and the refractive index is 2.05 to 2.15, for example, it can be one of 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or any two of the range values.

[0046] Optionally, in one embodiment, in the above step 101, after the anti-reflection layer is formed on both the front and back sides of the product, the front and back metal electrodes are prepared by screen printing, and then sintered to obtain a PERC cell. The front and back mother grids use silver paste, the front sub-grids use silver aluminum paste, and the back sub-grids use silver paste.

[0047] The silicon wafer after the anti-reflection film is formed is screen-printed to form a negative electrode grid line connected to the n-type doped region on the back side and a positive electrode grid line connected to the p-type doped region on the front side.

[0048] Optionally, in one implementation, in the above step 101, the dicing process includes:

[0049] The PERC cell is diced into cell halves using a laser.

[0050] In this embodiment, a laser scriber is used to scribe the PERC cell into cell halves from the back, which can quickly divide the cell into two.

[0051] In practical applications, the laser scribing machine needs to be placed after sintering to perform the scribing process before electrical injection.

[0052] Optionally, in one embodiment, the light source of the laser is green light, that is, using green laser to scribing the cell can better meet the needs of mass production and the effect of laser grooving. The wavelength of the green light can be specifically 532nm.

[0053] Optionally, in a specific embodiment, during the scribing process, the laser power is 50-70 W and the frequency is 1000-1500 Hz, which can cut the battery cell into half with less laser cut surface damage.

[0054] Optionally, in a specific embodiment, the irradiation time of the above-mentioned laser is 2 to 10 picoseconds, wherein the film opening size / uniformity of the picosecond laser is controllable and the damage to the cut surface is small.

[0055] In the embodiment of the present invention, electrical injection is to control the valence state and distribution of hydrogen in the solar cell by electrical means to achieve passivation of defects and impurities, which is essentially a hydrogen passivation mechanism introduced by current.

[0056] Optionally, in one implementation, in the above step 102, the battery half-cell is electrically injected, including:

[0057] The battery half-cell is electrically injected at a temperature of 220-280° C. and a current of 0-10A.

[0058] In this implementation, because the electric injection temperature is too low to effectively carry out electric injection, and too high a temperature will easily cause EL failure and damage the PN junction. In a semi-closed track with a temperature of 220 to 280°C and running through the front and back, a current of 0 to 10A is passed through the battery half-cell, which can effectively take into account the efficiency gain and the light and dark effects of the components, and can achieve efficient electric injection.

[0059] Optionally, in a specific implementation, the battery half-cell is electrically injected, comprising:

[0060] The battery half-cell is electrically injected at a temperature of 240-250° C. and a current of 5-8A.

[0061] Optionally, in a specific embodiment, the time for injecting electricity into the battery half-cell is 2200-3000s, which can effectively take into account both the production capacity and the efficiency gain of electricity injection. Optionally, in some embodiments, the time for electricity injection is any value among 2200s, 2400s, 2500s, 2600s, 2800s, 3000s, or any range of any two of them.

[0062] Optionally, in some embodiments, under the conditions of a temperature of 240 to 250° C. and a current of 5 to 8 A, the time for electrical injection into each battery half-cell is 2200 to 3000 s, which can quickly and efficiently complete the electron injection.

[0063] Optionally, in one embodiment, the battery half-cell is electrically injected, comprising:

[0064] The battery half-cell is sequentially injected with electricity through a plurality of cavities, and the total duration of the battery half-cell being injected with electricity in each of the cavities is 2200 to 3000 seconds.

[0065] In the embodiment of the present invention, multiple cavities are used to sequentially inject electricity into the battery for half a day, which can improve the overall efficiency of the battery for half a day of electricity injection.

[0066] The present invention also provides a PERC battery, which is prepared by the above method.

[0067] For the above-mentioned PERC battery embodiment, it is prepared by the above-mentioned method and can achieve the same technical effect. In order to avoid repetition, it will not be described here. For relevant matters, please refer to the partial description of the method embodiment.

[0068] In order to make the invention purpose, technical solution and beneficial effects of the present application clearer, the present application is further described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0069] The present invention is described in detail below by way of examples.

[0070] Example 1

[0071] Take 130 cells that were not electrically injected after PERC sintering, and perform IV tests to remove cells with obvious abnormal EL, and record the test results;

[0072] After the IV test, the cell was laser scribed from the back side, wherein the laser scribe used green light, the irradiation time was 2 picoseconds, the laser power was 50W, and the laser frequency was 1200Hz;

[0073] Perform IV test on the diced half cell and record the test results and total power;

[0074] The laser-sliced ​​cell was electrically injected, wherein the upper and lower temperatures of the cavity were 220°C, the current was 5A, and the injection time was 2400 seconds;

[0075] After electrical injection, IV test was performed and the test results and the total power PMPP of 130 cells were recorded.

[0076] The IV test results of the battery cells in Example 1 at different preparation stages are shown in Table 1.

[0077] Table 1

[0078]

[0079] It can be seen from Table 1 that the efficiency gain of the battery prepared in Example 1 from slicing to electrical injection is 0.24%, and the total power is increased by 12.12W, that is, there is basically no total power loss after slicing and then electrical injection.

[0080] Example 2

[0081] Take 150 cells that have not been electrically injected after PERC sintering, and perform IV tests to remove cells with obvious abnormal EL, and record the test results;

[0082] After the IV test, the cell was laser scribed from the back side, wherein the laser scribe used green light, the irradiation time was 2 picoseconds, the laser power was 50W, and the laser frequency was 1500Hz;

[0083] Perform IV test on the diced half cell and record the test results and total power;

[0084] The laser-sliced ​​cell was electrically injected, wherein the upper and lower temperatures of the cavity were 220°C, the current was 8A, and the injection time was 2800 seconds;

[0085] After electrical injection, perform IV test and record the test results and the total power PMPP of 150 cells.

[0086] The IV test results of the battery cells in Example 2 at different preparation stages are shown in Table 2.

[0087] Table 2

[0088]

[0089] It can be seen from Table 2 that the efficiency gain of the battery prepared in Example 2 from slicing to electrical injection is 0.217%, and the total power is increased by 10.84W, that is, there is basically no total power loss after slicing and then electrical injection.

[0090] Comparative Example 1

[0091] Take 130 cells that were not electrically injected after PERC sintering, and perform IV tests to remove cells with obvious abnormal EL, and record the test results;

[0092] After the IV test, the battery cells were electrically injected, wherein the upper and lower temperatures of the cavity were 220°C, the current was 5A, and the injection time was 2400 seconds. After the electrical injection, the IV test was performed and the test results and the total power PMPP of the 130 battery cells were recorded;

[0093] The battery cell after electricity injection is laser scribed from the back side, wherein the laser scribing uses green light, the radiation time is 2 picoseconds, the laser power is 50W, and the laser frequency is 1200Hz;

[0094] Perform IV test on the diced half cell and record the test results and total power.

[0095] The IV test results of the battery cells in Comparative Example 1 at different preparation stages are shown in Table 3.

[0096] Table 3

[0097]

[0098]

[0099] It can be seen from Table 3 that the efficiency gain of the battery prepared in Comparative Example 1 before and after electrical injection is 0.21%, and the total power increases by 9.09 W, but the efficiency before and after laser scribing decreases by 0.23%, and the total power decreases by 9.96 W, that is, the total power is reduced after electrical injection and then scribing.

[0100] Comparative Example 2

[0101] Take 150 cells that have not been electrically injected after PERC sintering, and perform IV tests to remove cells with obvious abnormal EL, and record the test results;

[0102] After the IV test, the battery cells were electrically injected, wherein the upper and lower temperatures of the cavity were 220°C, the current was 8A, and the injection time was 2800 seconds. After the electrical injection, the IV test was performed and the test results and the total power PMPP of the 150 battery cells were recorded;

[0103] The battery cell after electricity injection is laser scribed from the back side, wherein the laser scribing uses green light, the irradiation time is 2 picoseconds, the laser power is 50W, and the laser frequency is 1500Hz;

[0104] Perform IV test on the diced half cell and record the test results and total power.

[0105] The IV test results of the battery cells in Comparative Example 2 at different preparation stages are shown in Table 4.

[0106] Table 4

[0107]

[0108] It can be seen from Table 4 that the efficiency gain of the battery prepared in Comparative Example 2 before and after electrical injection is 0.218%, and the total power increases by 10.85 W, but the efficiency decreases by 0.259% before and after laser scribing, and the total power decreases by 12.93 W, that is, the total power is significantly reduced after electrical injection and then scribing.

[0109] In summary, in this embodiment, the preparation method of the PERC cell provided is to slice the PERC cell after sintering to form the electrode grid lines into half-cells, and then perform electrical injection on the half-cells to obtain the PERC cell. Among them, the sintered PERC cell is first sliced ​​and then electrically injected. The principle of electrical injection can be used to activate the atoms in the silicon nitride passivation film, and the valence state of the H atoms is controlled by current introduction, so that they are combined with the recombination center at the N+ emitter and the P substrate to form a non-recombination center, thereby achieving passivation repair of the slicing wound, thereby effectively solving the problem of excessive efficiency loss after slicing of PERC cells made by the existing method.

[0110] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0111] The PERC battery and the preparation method thereof provided by the present invention are introduced in detail above. The principle and implementation mode of the present invention are explained by using specific examples herein. The description of the above embodiments is only used to help understand the method and the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and the scope of application. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a PERC battery, characterized in that: include: Slice the PERC cell after sintering to form the electrode grid lines into half cells; The battery half-cell is electrically injected to obtain a PERC battery.

2. The method for preparing a PERC cell according to claim 1, characterized in that: The PERC cell after sintering to form the electrode grid lines is cut into half cells, including: The PERC cell is diced into cell halves using a laser.

3. The method for preparing a PERC cell according to claim 2, characterized in that: The light source of the laser is green light.

4. The method for preparing a PERC cell according to claim 3, characterized in that: In the scribing process, the laser power is 50-70 W and the frequency is 1000-1500 Hz.

5. The method for preparing a PERC cell according to claim 3, characterized in that: The irradiation time of the laser is 2 to 10 picoseconds.

6. The method for preparing a PERC cell according to claim 1, characterized in that: The battery half-cell is electrically injected, comprising: The battery half-cell is electrically injected at a temperature of 220-280° C. and a current of 0-10A.

7. The method for preparing a PERC cell according to claim 5, characterized in that: The battery half-cell is electrically injected, comprising: The battery half-cell is electrically injected at a temperature of 240-250° C. and a current of 5-8A.

8. The method for preparing a PERC cell according to claim 6, characterized in that: The electrical injection time is 2200 to 3000 seconds.

9. The method for preparing a PERC cell according to claim 8, characterized in that: The battery half-cell is electrically injected, comprising: The battery half-cell is sequentially injected with electricity through a plurality of cavities, and the total duration of the battery half-cell being injected with electricity in each of the cavities is 2200 to 3000 seconds.

10. A PERC battery, characterized in that: The method is prepared by any one of claims 1 to 9.

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