A TOPCon solar cell and its preparation process
By adding laser-induced sintering (LIS) to the TOPCon solar cell fabrication process, the control problem of the SE doping step was solved, more efficient contact between silicon wafers and metal electrodes was achieved, and cell efficiency and production capacity were improved.
Patent Information
- Application Number
- CN202411264213.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-10
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-09-10
AI Technical Summary
In the existing TOPCon solar cell preparation process, the SE doping step is difficult to control, easily damages the silicon substrate, and increases the risk of the slurry burning through the amorphous silicon layer and destroying the tunneling structure, resulting in high labor costs and complexity.
After light injection, laser-induced sintering treatment is added to use the local current generated by the laser to reduce the contact resistivity between the silicon wafer and the metal electrode, and to form an ohmic contact of silver-silicon alloy at high temperature, thereby simplifying the preparation process and reducing damage to the silicon substrate.
It improves the conversion efficiency of TOPCon solar cells, simplifies the process flow, reduces labor costs and non-silicon costs, and increases production capacity.
Smart Images
Figure CN119092561B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar cells, and in particular to a TOPcon solar cell and a preparation process thereof. Background Art
[0002] SE (selective emitter) doping is an important step in the preparation process of TOPCon (Tunnel Oxide Passivated Contact) solar cells. After boron diffusion on the back of the silicon wafer, the metal grid line and the silicon wafer contact part are heavily doped, while other positions remain lightly doped, thereby reducing the series resistance of the solar cell and reducing surface recombination, which has the advantages of improving the short-circuit current and open-circuit voltage of the solar cell. However, SE doping uses direct laser doping, and the required laser power control window is narrow, and the energy stability requirements are high. It is not only easy to damage the silicon substrate, but also further increases the risk of the slurry burning through the amorphous silicon layer and destroying the tunneling structure. At the same time, SE doping has higher requirements for the matching of the previous and next processes and the difficulty of control, and also requires higher labor costs. Therefore, it is of practical value to develop a preparation process for TOPCon solar cells that is easier to control, has low labor costs, and has high efficiency. Summary of the Invention
[0003] In view of the shortcomings of the prior art, the present invention aims to provide a preparation process of a TOPcon solar cell.
[0004] In order to achieve the above object, the present invention adopts the following technical solutions:
[0005] In a first aspect, the present invention provides a process for preparing a TOPCon solar cell, the process comprising the following steps:
[0006] (1) Cleaning and texturing the silicon wafer;
[0007] (2) Boron diffusion is performed on the back and front of the silicon wafer after texturing respectively;
[0008] (3) removing the borosilicate glass (BSG) layer on the front and back sides of the silicon wafer, performing alkali polishing on the back side of the silicon wafer, and sequentially depositing a tunneling layer and an amorphous silicon passivation layer on the back side of the silicon wafer;
[0009] (4) performing tubular phosphorus diffusion on the amorphous silicon on the back of the silicon wafer;
[0010] (5) removing the phosphosilicate glass (PSG) layer on the front and back sides of the silicon wafer and depositing an aluminum oxide passivation layer on the front side of the silicon wafer;
[0011] (6) depositing anti-reflection layers on the front and back of the silicon wafer;
[0012] (7) Screen printing metal electrodes and patterns on the front and back of the silicon wafer;
[0013] (8) Sintering the silicon wafer and then performing light injection;
[0014] (9) Laser induced sintering of silicon wafers at 850-950°C;
[0015] (10) Testing and sorting of TOPCon solar cells.
[0016] The preparation process of the TOPCon solar cell of the present invention adds a laser-induced sintering step after screen printing and sintering. The hot spots caused by laser heating will locally and precisely destroy the amorphous silicon passivation layer on the silicon wafer, allowing silver to form direct contact with the silicon wafer. At the same time, under the action of high temperature, a silver-silicon alloy is formed locally on the silicon wafer, forming an ohmic contact, thereby improving the conversion efficiency of the TOPCon solar cell.
[0017] Furthermore, in the step (2), when the boron is diffused on the back of the silicon wafer after texturing, the diffusion temperature is controlled between 820 and 1050 ° C, and the surface concentration is controlled at 5.2×10 19 cm -3 ~5.5×10 19 cm -3 The node depth is controlled between 0.2 and 0.28 μm, and the square resistance is controlled between 155 and 175 Ω / sqr. When the boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is controlled at 4.8×10 18 cm -3 ~5.1×10 19 cm -3 The node depth is controlled between 0.62 and 0.67 μm, and the square resistance is controlled between 280 and 340 Ω / sqr.
[0018] Furthermore, in step (3), the thickness of the amorphous silicon passivation layer is 120 to 180 nm, which provides good surface passivation for the back of the silicon wafer, reduces the number of surface dangling bonds and defects, thereby reducing the surface recombination rate, and helps to improve the open circuit voltage and short circuit current of the TOPCon solar cell.
[0019] Furthermore, in step (4), when the amorphous silicon on the back of the silicon wafer is subjected to tubular phosphorus diffusion, the diffusion temperature is controlled between 800 and 900°C, and the surface concentration is controlled at 1.5×10 20 cm -3 ~2.2×10 20 cm -3 The node depth is controlled between 0.18 and 0.2 μm, and the square resistance is controlled between 40 and 60 Ω / sqr.
[0020] Furthermore, in step (5), wet etching is used to remove the PSG layer on the front and edge of the silicon wafer to expose the amorphous silicon passivation layer coated on the front, and then the amorphous silicon passivation layer on the front of the silicon wafer and the residual PSG, BSG layer and the PSG layer on the back of the silicon wafer are removed by RCA cleaning.
[0021] Furthermore, in step (6), the anti-reflection layer is made of SiN x , which greatly reduces the reflectivity of sunlight on the surface of the silicon wafer, thereby increasing the light absorption rate of the solar cell.
[0022] Furthermore, in step (7), the screen-printed metal electrode uses a silver-silicon alloy formed by printing and sintering, which helps to reduce the resistance of the battery surface, thereby increasing the open circuit voltage of the solar cell.
[0023] Furthermore, in step (8), the sintering temperature is controlled between 670° C. and 730° C., so that impurities and defects in the silicon wafer diffuse and recrystallize.
[0024] Furthermore, in step (9), the laser induced sintering treatment is set with a bias voltage of 20 to 50 V, a laser power of 5 to 25%, a laser wavelength of 450 to 1000 nm, a laser frequency of 100 to 500 kHz, and a peak energy of 4.5 to 11.0 J / cm 2 The laser scan speed is 4 to 40 m / s, the laser spot diameter is 10 to 35 μm, and the processing time is 0.5 to 3 seconds. High-intensity laser pulses are applied locally to the front of the silicon wafer while maintaining a constant reverse voltage. The local current generated by the laser significantly reduces the contact resistivity between the silicon wafer and the metal electrode.
[0025] Furthermore, in step (9), the laser wavelength is controlled between 500 and 600 nm.
[0026] Furthermore, in step (9), the temperature of the laser induced sintering treatment is 850-900°C.
[0027] Furthermore, in step (10), after the laser-induced sintering process is completed, the TOPCon solar cells are subjected to appearance testing, efficiency testing, and EL testing. TOPCon solar cells are classified based on conversion efficiency, open-circuit voltage, EL characteristics, and appearance characteristics of the cells to ensure the quality of the TOPCon solar cells.
[0028] Furthermore, the silicon wafer is an N-type silicon wafer.
[0029] In a second aspect, the present invention provides a TOPCon solar cell, wherein the selective emitter cell is prepared using the preparation process described in the second aspect.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] (1) The present invention removes the SE doping step in the preparation process of TOPCon solar cells and adds a laser-induced sintering process after light injection. The local current generated by the laser significantly reduces the contact resistivity between the silicon wafer and the metal electrode, thereby improving the efficiency of the TOPCon solar cell while reducing damage to the silicon substrate. In addition, the process is easier to control and requires less labor than SE doping.
[0032] (2) The present invention adds a laser-induced sintering process after light injection into the TOPCon solar cell. The hot spots caused by laser heating will locally and precisely destroy the amorphous silicon passivation layer on the silicon wafer, allowing silver to directly contact the silicon wafer. This not only establishes an effective electron transmission path, but also forms a silver-silicon alloy locally on the silicon wafer under high temperature conditions, providing ohmic contact and improving the open circuit voltage and fill factor.
[0033] (3) The TOPCon solar cell preparation process of the present invention can significantly shorten the production process time of TOPCon solar energy, effectively increase production capacity, and reduce non-silicon costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0035] Figure 1 This is a flow chart of the preparation process of a TOPCon solar cell provided in Example 1 of the present invention. DETAILED DESCRIPTION
[0036] The following will clearly and completely describe the technical solutions of the present invention in conjunction with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0037] Example 1
[0038] This embodiment provides a preparation process of a TOPCon solar cell. Figure 1 As shown, the preparation process includes the following steps:
[0039] (1) Cleaning and texturing the N-type silicon wafer;
[0040] (2) Boron diffusion was performed on the back and front of the silicon wafer after texturing at 935°C. The surface concentration of the back of the silicon wafer was 5.4×10 19 cm -3 , the node depth is 0.24um, and the square resistance is 165Ω / sqr; when the boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is 2.7×10 19 cm -3 , the node depth is 0.65um and the square resistance is 310Ω / sqr;
[0041] (3) removing the borosilicate glass (BSG) layer on the front and back sides of the silicon wafer, performing a wet chemical alkali polishing on the back side of the silicon wafer, and sequentially depositing a tunneling layer and an amorphous silicon passivation layer on the back side of the silicon wafer, wherein the thickness of the amorphous silicon passivation layer is 150 nm;
[0042] (4) The amorphous silicon on the back of the silicon wafer was subjected to tubular phosphorus diffusion at 850°C. The surface concentration of the tubular phosphorus diffusion was 1.8×10 20 cm -3 , the node depth is 0.19um and the square resistance is 50Ω / sqr;
[0043] (5) Using wet etching to remove the PSG layer on the front and edge of the silicon wafer to expose the amorphous silicon passivation layer on the front, and then using RCA cleaning to remove the amorphous silicon passivation layer and the remaining PSG and BSG layers on the front of the silicon wafer, as well as the PSG layer on the back of the silicon wafer, and depositing an aluminum oxide passivation layer on the front of the silicon wafer;
[0044] (6) Deposit anti-reflection layer SiN on the front and back of the silicon wafer x ;
[0045] (7) Ag / Al screen-printed metal electrodes and patterns formed by printing and sintering on the front and back of the silicon wafer;
[0046] (8) Sintering the silicon wafer at 700°C and then performing light injection;
[0047] (9) The silicon wafer was subjected to laser induced sintering at 850°C, wherein the laser induced sintering process was set with a bias voltage of 35V, a laser power of 15%, a laser wavelength of 700nm, a laser frequency of 300kHz, and a peak energy of 8.0J / cm 2 , the laser scanning speed is 20m / s, the laser spot diameter is 25um, and the processing time is 2s;
[0048] (10) Perform appearance test, efficiency test and EL test on TOPCon solar cells. And classify TOPCon solar cells according to conversion efficiency, open circuit voltage, EL characteristics and appearance characteristics of the cell to ensure the quality of TOPCon solar cells.
[0049] Example 2
[0050] This embodiment provides a preparation process of a TOPCon solar cell, which comprises the following steps:
[0051] (1) Cleaning and texturing the N-type silicon wafer;
[0052] (2) Boron diffusion was performed on the back and front of the silicon wafer after texturing at 820°C. The surface concentration of the back of the silicon wafer was 5.2×10 19 cm -3 , the node depth is 0.2um, and the square resistance is 155Ω / sqr; when the boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is 4.8×10 18 cm -3 , the node depth is 0.62um and the square resistance is 280Ω / sqr;
[0053] (3) removing the borosilicate glass (BSG) layer on the front and back sides of the silicon wafer, performing a wet chemical alkali polishing on the back side of the silicon wafer, and sequentially depositing a tunneling layer and an amorphous silicon passivation layer on the back side of the silicon wafer. The thickness of the amorphous silicon passivation layer is 120 nm.
[0054] (4) The amorphous silicon on the back of the silicon wafer was subjected to tubular phosphorus diffusion at 800°C. The surface concentration of the tubular phosphorus diffusion was 1.5×10 20 cm -3 , the node depth is 0.18um and the square resistance is 60Ω / sqr;
[0055] (5) Using wet etching to remove the PSG layer on the front and edge of the silicon wafer to expose the amorphous silicon passivation layer on the front, and then using RCA cleaning to remove the amorphous silicon passivation layer and the remaining PSG and BSG layers on the front of the silicon wafer, as well as the PSG layer on the back of the silicon wafer, and depositing an aluminum oxide passivation layer on the front of the silicon wafer;
[0056] (6) Deposit anti-reflection layer SiN on the front and back of the silicon wafer x ;
[0057] (7) Ag / Al screen-printed metal electrodes and patterns formed by printing and sintering on the front and back of the silicon wafer;
[0058] (8) Sintering the silicon wafer at 670°C and then performing light injection;
[0059] (9) The silicon wafer was subjected to laser induced sintering at 850°C, wherein the laser induced sintering process was set with a bias voltage of 20 V, a laser power of 5%, a laser wavelength of 450 nm, a laser frequency of 100 kHz, and a peak energy of 4.5 J / cm 2 , the laser scanning speed is 4m / s, the laser spot diameter is 35um, and the processing time is 0.5s;
[0060] (10) Perform appearance test, efficiency test and EL test on TOPCon solar cells. And classify TOPCon solar cells according to conversion efficiency, open circuit voltage, EL characteristics and appearance characteristics of the cell to ensure the quality of TOPCon solar cells.
[0061] Example 3
[0062] This embodiment provides a preparation process of a TOPCon solar cell, which comprises the following steps:
[0063] (1) Cleaning and texturing the N-type silicon wafer;
[0064] (2) Boron diffusion was performed on the back and front of the silicon wafer after texturing at 1050°C. The surface concentration of the back of the silicon wafer was 5.5×10 19 cm -3 , the node depth is 0.28um, and the square resistance is 175Ω / sqr; when boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is 5.1×10 19 cm -3 , the node depth is 0.67um and the square resistance is 340Ω / sqr;
[0065] (3) removing the borosilicate glass (BSG) layer on the front and back sides of the silicon wafer, performing a wet chemical alkali polishing on the back side of the silicon wafer, and sequentially depositing a tunneling layer and an amorphous silicon passivation layer on the back side of the silicon wafer. The thickness of the amorphous silicon passivation layer is 180 nm.
[0066] (4) The amorphous silicon on the back of the silicon wafer was subjected to tubular phosphorus diffusion at 900°C. The surface concentration of the tubular phosphorus diffusion was 2.2×10 20 cm -3 , section depth 0.2um, square resistance 60Ω / sqr;
[0067] (5) Using wet etching to remove the PSG layer on the front and edge of the silicon wafer to expose the amorphous silicon passivation layer on the front, and then using RCA cleaning to remove the amorphous silicon passivation layer and the remaining PSG and BSG layers on the front of the silicon wafer, as well as the PSG layer on the back of the silicon wafer, and depositing an aluminum oxide passivation layer on the front of the silicon wafer;
[0068] (6) Deposit anti-reflection layer SiN on the front and back of the silicon wafer x ;
[0069] (7) Ag / Al screen-printed metal electrodes and patterns formed by printing and sintering on the front and back of the silicon wafer;
[0070] (8) Sintering the silicon wafer at 730°C and then performing light injection;
[0071] (9) The silicon wafer was subjected to laser induced sintering at 950°C, wherein the laser induced sintering process was set with a bias voltage of 50 V, a laser power of 25%, a laser wavelength of 1000 nm, a laser frequency of 500 kHz, and a peak energy of 11.0 J / cm 2 , the laser scanning speed is 40m / s, the laser spot diameter is 35um, and the processing time is 3s;
[0072] (10) Perform appearance test, efficiency test and EL test on TOPCon solar cells. And classify TOPCon solar cells according to conversion efficiency, open circuit voltage, EL characteristics and appearance characteristics of the cell to ensure the quality of TOPCon solar cells.
[0073] Example 4
[0074] This embodiment provides a preparation process for a TOPCon solar cell. The difference between this embodiment and Example 1 is that the laser wavelength of the laser-induced sintering treatment in step (9) is 400 nm, and the remaining steps and parameters are consistent with Example 1.
[0075] Example 5
[0076] This embodiment provides a preparation process for a TOPCon solar cell. The difference between this embodiment and Example 1 is that the laser wavelength of the laser-induced sintering treatment in step (9) is 1050 nm, and the remaining steps and parameters are consistent with Example 1.
[0077] Example 6
[0078] This embodiment provides a preparation process for a TOPCon solar cell. The difference between this embodiment and Example 1 is that the laser wavelength of the laser-induced sintering treatment in step (9) is 500 nm, and the remaining steps and parameters are consistent with Example 1.
[0079] Example 7
[0080] This embodiment provides a preparation process for a TOPCon solar cell. The difference between this embodiment and Example 1 is that the laser wavelength of the laser-induced sintering treatment in step (9) is 600 nm, and the remaining steps and parameters are consistent with Example 1.
[0081] Example 8
[0082] This embodiment provides a preparation process for a TOPCon solar cell. The difference between this embodiment and Example 1 is that the temperature of the laser-induced sintering treatment in step (9) is 900°C, and the remaining steps and parameters are consistent with Example 1.
[0083] Comparative Example 1
[0084] This comparative example provides a preparation process for a TOPCon solar cell. The difference between this comparative example and Example 1 is that the temperature of the laser-induced sintering treatment in step (9) is 820°C, and the remaining steps and parameters are consistent with Example 1.
[0085] Comparative Example 2
[0086] This comparative example provides a preparation process for a TOPCon solar cell. The difference between this comparative example and Example 1 is that the temperature of the laser-induced sintering treatment in step (9) is 970°C, and the remaining steps and parameters are consistent with Example 1.
[0087] Comparative Example 3
[0088] The difference between this comparative example and Example 1 is that there is no laser induced sintering treatment in step (10), and the remaining steps and parameters are consistent with Example 1.
[0089] Comparative Example 4
[0090] This comparative example differs from Example 1 in that the laser induced sintering treatment in step (10) is omitted, and step (2) includes:
[0091] (2.a) Boron diffusion on the back of the silicon wafer after texturing at X°C, the surface concentration on the back of the silicon wafer is 5.4×10 19 cm -3 , the node depth is 0.24um and the square resistance is 165Ω / sqr;
[0092] (2.b) Laser doping is performed on the metal gate line area of the boron-diffused silicon wafer, so that the laser area is heavily doped and the non-laser area is lightly doped;
[0093] (2.c) Boron diffusion is performed on the front side of the silicon wafer after texturing at X°C. The surface concentration on the back side of the silicon wafer is 5.4×10 19 cm -3 , the node depth is 0.24um, and the square resistance is 165Ω / sqr; when the boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is 2.7×10 19 cm -3 , the node depth is 0.65um and the square resistance is 310Ω / sqr.
[0094] Performance Testing
[0095] The electrical performance of the TOPCon solar cells prepared in Examples 1-6 and Comparative Examples 1-2 was tested.
[0096] The test method is: using an IV tester to measure the various parameters of the solar cell, the results are shown in Table 1.
[0097] Table 1 Test results of batteries of Examples and Comparative Examples
[0098]
[0099]
[0100] Performance test data conclusion analysis:
[0101] As can be seen from the table above, the present invention eliminates the SE doping process, simplifies the process flow, saves production costs, reduces the impact on silicon substrate quality, reduces process defect rates, and achieves performance improvements. Moreover, the process is easier to control and requires less labor than SE doping. In addition, the TOPCon solar cell prepared based on the TOPCon solar cell preparation process provided by the present invention has excellent conversion efficiency.
[0102] First, compared with Example 4 with a laser wavelength of 400 nm and Example 5 with a laser wavelength of 1050 nm in the laser induced sintering process, Example 1 with a laser wavelength of 700 nm has a higher open circuit voltage (Uoc) and fill factor (FF) of the prepared TOPCon solar cell, can form a better silver-silicon contact, and achieve better photoelectric conversion efficiency; and compared with Example 1, Example 6 and Example 7 with laser wavelengths of 500 nm and 600 nm respectively, the prepared battery contacts are more complete, the open circuit voltage (Uoc) and fill factor (FF) are more significantly improved, and the efficiency gain is higher, which shows that it is best to control the laser wavelength in the laser induced sintering process at 500-600 nm.
[0103] Secondly, comparing Example 1 with a laser sintering temperature of 850°C and Example 8 with a laser induced sintering temperature of 900°C, the battery prepared in Example 8 has a higher filling factor (FF) and better performance, while Comparative Example 1 with a laser sintering temperature of 820°C and Comparative Example 2 with a laser sintering temperature of 970°C, compared with Example 1, the laser sintering temperature in Comparative Example 1 is low, resulting in incomplete contact, a low filling factor (FF) of the prepared battery, poor wear resistance, and low efficiency; while the laser sintering temperature in Comparative Example 2 is high, resulting in overburning and local breakdown, and the prepared battery has a significant loss in open circuit voltage (Uoc) and low efficiency. This shows that the higher the laser sintering temperature, the more significant the loss in open circuit voltage (Uoc) of the battery and local breakdown. If the laser sintering temperature is too low, it will also lead to incomplete contact and a low filling factor (FF).
[0104] Finally, by comparing Example 1 with Comparative Examples 3-4, Comparative Example 3 does not have the laser induced sintering treatment of step (10), resulting in the inability to form a good silver-silicon alloy and ohmic contact; in Comparative Example 4, step (2) includes SE doping, and there is no laser induced sintering treatment of step (10), resulting in a shallow silver-silicon alloy layer, a large contact resistance, and low open circuit voltage (Uoc) and short circuit current (Isc); this shows that adding laser induced sintering treatment after light injection can effectively reduce contact resistance, improve silver-silicon contact, and significantly improve open circuit voltage (Uoc) and fill factor (FF), thereby achieving the purpose of improving efficiency.
[0105] The present invention simplifies the process flow and reduces the impact on the quality of the silicon substrate by directly removing the SE doping step during boron diffusion on the silicon wafer, thereby reducing the process complexity and cost. Then, a laser-induced sintering treatment is added after light injection, and the local current generated by the laser is used to significantly reduce the contact resistivity between the silicon wafer and the metal electrode. In addition, the hot spots caused by laser heating will locally and accurately destroy the amorphous silicon passivation layer on the silicon wafer, allowing silver to directly contact the silicon wafer. This not only establishes an effective electron transmission path, but also forms a silver-silicon alloy locally on the silicon wafer under high temperature conditions, with ohmic contact, thereby improving the open circuit voltage and fill factor, thereby improving the conversion efficiency of the TOPCon solar cell.
[0106] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.
Claims
1. A process for preparing a TOPCon solar cell, characterized in that: The preparation process consists of the following steps: (1) Cleaning and texturing the silicon wafer; (2) Boron diffusion is performed on the back and front sides of the silicon wafer after texturing; (3) Remove the borosilicate glass (BSG) layer on the front and back of the silicon wafer, perform alkali polishing on the back of the silicon wafer, and deposit a tunneling layer and an amorphous silicon passivation layer on the back of the silicon wafer in sequence; (4) Perform tubular phosphorus diffusion on the amorphous silicon on the back of the silicon wafer; (5) Remove the phosphosilicate glass (PSG) layer on the front and back of the silicon wafer and deposit an aluminum oxide passivation layer on the front of the silicon wafer; (6) Depositing anti-reflection layers on the front and back of the silicon wafer; (7) Screen printing metal electrodes and patterns on the front and back of the silicon wafer; (8) Sintering the silicon wafer and then performing light injection; (9) Laser induced sintering of silicon wafers at 850-950°C; (10) Testing and sorting TOPCon solar cells; Wherein, in said step (9), the laser wavelength is 500-600 nm; In the step (2), when the boron is diffused on the back of the silicon wafer after texturing, the diffusion temperature is controlled between 820 and 1050 ° C, and the surface concentration is controlled at 5.2×10 19 cm -3 ~5.5×10 19 cm -3 The node depth is controlled between 0.2 and 0.28 μm, and the square resistance is controlled between 155 and 175 Ω / sqr. When the boron diffusion is performed on the front side of the silicon wafer after texturing, the surface concentration is controlled at 4.8×10 18 cm -3 ~5.1×10 19 cm -3 The node depth is controlled between 0.62 and 0.67 μm, and the square resistance is controlled between 280 and 340 Ω / sqr; In the step (3), the thickness of the amorphous silicon passivation layer is 120 to 180 nm; In step (4), when the amorphous silicon on the back of the silicon wafer is subjected to tubular phosphorus diffusion, the diffusion temperature is controlled between 800 and 900 ° C, and the surface concentration is controlled at 1.5×10 20 cm -3 ~2.2 × 10 20 cm -3 The node depth is controlled between 0.18 and 0.2 μm, and the square resistance is controlled between 40 and 60 Ω / sqr.
2. The preparation process according to claim 1, characterized in that In the step (5), wet etching is used to remove the PSG layer on the front and edge of the silicon wafer to expose the amorphous silicon passivation layer coated on the front, and then the amorphous silicon passivation layer on the front of the silicon wafer and the remaining PSG and BSG layers and the PSG layer on the back of the silicon wafer are removed by RCA cleaning.
3. The preparation process according to claim 1, characterized in that In the step (7), the screen-printed metal electrode is a silver-silicon alloy formed by printing and sintering.
4. The preparation process according to claim 1, characterized in that In the step (8), the sintering temperature is controlled between 670 and 730°C.
5. The preparation process according to claim 1, characterized in that: In step (9), the laser induced sintering treatment is set with a bias voltage of 20 to 50 V, a laser power of 5 to 25%, a laser frequency of 100 to 500 kHz, and a peak energy of 4.5 to 11.0 J / cm 2 The scanning speed of the laser is 4 to 40 m / s, the spot diameter of the laser is 10 to 35 μm, and the processing time is 0.5 to 3 s.
6. A TOPCon solar cell, characterized in that: The TOPCon solar cell is prepared by the preparation process according to any one of claims 1 to 5.
Citation Information
Patent Citations
Preparation method of TOPcon solar cell with double-sided SE
CN116864568A