Method for passivating cutting edge of silicon-based solar cell
By forming a SiOx/AZO/Al2O3 or SiOx/BZO/Al2O3 edge passivation stack layer on the cutting edge of a silicon-based solar cell, the edge recombination problem caused by laser cutting is solved, the battery efficiency is improved, and an effective passivation effect is achieved.
Patent Information
- Application Number
- CN202510266228.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-07-01
AI Technical Summary
Silicon-based solar cells have severe edge recombination during laser cutting, resulting in reduced efficiency. The existing passivation methods are difficult to achieve or have poor results in industrial mass production.
SiOx/AZO/Al2O3 or SiOx/BZO/Al2O3 edge passivation stack is formed at the cutting edge of the sliced solar cell, and a silicon oxide layer is formed by ultraviolet ozone treatment or oxygen plasma treatment, followed by an aluminum or boron-doped zinc oxide layer outside the silicon oxide layer, and an aluminum oxide cap layer is added, and annealing is performed to activate the chemical passivation of hydrogen.
It improves the chemical passivation and field effect passivation performance of sliced solar cells, repairs edge damage caused by laser cutting, and improves battery efficiency.
Smart Images
Figure CN120239353A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar cells, and particularly to a method for passivating the cutting edge of a silicon-based solar cell. Background Art
[0002] In order to increase the output power density of solar cell devices, one method is to improve the absolute efficiency of a single solar cell, and another method is to interconnect the back electrodes of multiple solar cells with the front electrodes of adjacent cells to increase the output power density of the module. The latter shingling reduces the cell gap and increases the photosensitive area of the module, reduces the shading loss of the visible electrodes, and reduces the resistance loss of the current collection. Its potential is self-evident. For example, the corresponding shingled solar cell technology has appeared in publications and patents and has also been promoted in commercial cell modules.
[0003] However, shingled cells are usually assembled from half-cells cut from a whole cell. Silicon-based solar cells, including tunnel oxide passivated contact (TOPCon) cells and back contact (BC) cells, require laser cutting during module preparation; edge recombination will occur during the cutting process, resulting in a reduction in the efficiency of solar cells. If the cell size is further reduced, whether it is a whole cell or a half-cell after cutting, small-sized cells have a much larger perimeter-to-area ratio, which makes edge recombination even more serious, resulting in open-circuit voltage (V OC ) and fill factor (FF) losses. To reduce such losses, there are currently the following methods: 1. Achieve surface long passivation effect by strongly doping the edge to repel edge carriers and prevent edge recombination; 2. Etch the edge by wet chemical method and passivate the edge by thermally growing silicon oxide; 3. Passivate the edge by growing aluminum oxide and annealing it in an electron injection annealing furnace. However, according to the first two edge passivation methods, several additional pre-metallization process steps or post-metallization chemical etching processes are required to produce such cells, which makes it challenging to achieve industrial mass production; although the third edge passivation method can greatly reduce the difficulty of industrial mass production, its passivation effect is not ideal. Summary of the Invention
[0004] In order to solve the above technical problems, the present invention provides a method for passivating the cutting edge of a silicon-based solar cell.
[0005] To achieve the above object, the present invention is implemented according to the following technical solution:
[0006] A method for passivating the cutting edge of a silicon-based solar cell includes the following steps:
[0007] S1. Laser cut the silicon-based solar cell into sliced solar cells;
[0008] S2. Subject the sliced solar cell to ultraviolet ozone treatment or oxygen plasma treatment to form a silicon oxide layer on the cutting edge of the sliced solar cell;
[0009] S3. Place the sliced solar cell into an atomic layer deposition chamber to form an aluminum-doped zinc oxide (AZO) layer or a boron-doped zinc oxide (BZO) layer outside the silicon oxide layer on the cutting edge of the sliced solar cell;
[0010] S4. Place the sliced solar cell into an atomic layer deposition chamber to form an aluminum oxide capping layer outside the aluminum-doped zinc oxide layer or the boron-doped zinc oxide layer on the cutting edge of the sliced solar cell; finally, form a SiO x / AZO / Al2O3 or SiO x / BZO / Al2O3 edge passivation stack layer;
[0011] S5. Anneal the sliced solar cell with the formed SiO x / AZO / Al2O3 or SiO x / BZO / Al2O3 edge passivation stack layer to activate the chemical passivation of hydrogen.
[0012] Furthermore, in step S2, the temperature of the ultraviolet ozone treatment is 25 - 200 °C, and the time is 10 - 600 s. More preferably, the temperature of the ultraviolet ozone treatment is 50 °C, and the time of the ultraviolet ozone treatment is 300 s.
[0013] Furthermore, in step S2, the process of the oxygen plasma treatment is as follows: heat the chamber, place the sliced solar cell into the chamber, pad the back to be empty, evacuate to a vacuum degree lower than 5E-2 torr, perform oxygen plasma treatment on the sliced solar cell, the oxygen plasma treatment time is 1 s - 20 s, the oxygen plasma treatment power is 20 - 250 W, the oxygen flow rate is 25 - 200 sccm, and form a silicon oxide layer with a thickness of 0.5 nm - 3 nm. More preferably, the oxygen plasma treatment time is 4 s, the oxygen plasma treatment power is 80 W, the oxygen flow rate is 50 sccm, and the thickness of the silicon oxide is 1 nm.
[0014] Furthermore, in step S3, the preparation process of the aluminum-doped zinc oxide (AZO) layer is as follows:
[0015] (1) Fix the sliced solar cell using an in-slot fixture and then vertically place the sliced solar cell into the atomic layer deposition chamber. The exposed part of the sliced solar cell is the cutting edge of the sliced solar cell;
[0016] (2) Heat the chamber to 100 - 300 °C, turn on the mechanical pump switch to evacuate the chamber to a vacuum degree lower than 5E-2 torr; first perform n cycles of growth of the transition metal zinc precursor and the oxygen precursor to form a zinc oxide layer outside the silicon oxide layer, and then perform one cycle of growth of the aluminum precursor and the oxygen precursor to form an aluminum oxide layer outside the zinc oxide layer, or first perform one cycle of growth of the aluminum precursor and the oxygen precursor to form an aluminum oxide layer outside the zinc oxide layer, and then perform n cycles of growth of the transition metal zinc precursor and the oxygen precursor to form a zinc oxide layer outside the silicon oxide layer. This is one small cycle; perform N small cycles to obtain an aluminum-doped zinc oxide AZO layer with a thickness of 2 nm - 30 nm. Further preferably, the thickness of the AZO layer is 8 nm - 18 nm.
[0017] Further, in the step S3, the preparation process of the boron-doped zinc oxide BZO layer is as follows:
[0018] 1) Use an insert-type fixture to fix the sliced solar cell and vertically place the sliced solar cell into the atomic layer deposition chamber. The exposed part of the sliced solar cell is the cutting edge of the sliced solar cell.
[0019] 2) Heat the chamber to 100 - 300 °C, turn on the mechanical pump switch to evacuate the chamber to a vacuum degree lower than 5E-2 torr; first perform n cycles of growth of the transition metal zinc precursor and the oxygen precursor to form a zinc oxide layer outside the silicon oxide layer, and then perform one cycle of growth of the boron precursor and the oxygen precursor to form a boron oxide layer outside the zinc oxide layer, or first perform one cycle of growth of the boron precursor and the oxygen precursor to form a boron oxide layer outside the zinc oxide layer, and then perform n cycles of growth of the transition metal zinc precursor and the oxygen precursor to form a zinc oxide layer outside the silicon oxide layer. This is one small cycle; perform N small cycles to obtain a boron-doped zinc oxide BZO layer with a thickness of 2 nm - 15 nm; further preferably, the thickness of the BZO layer is 6 nm - 10 nm.
[0020] Further, the transition metal zinc precursor is one of dimethyl zinc, diethyl zinc, zinc acetylacetonate, zinc chloride, and zinc methoxide compound; the aluminum precursor is one of trimethyl aluminum, triethyl aluminum, aluminum chloride, aluminum isopropoxide, diisopropyl acetylacetonate aluminum, and aluminum trifluoride; the oxygen precursor is one of deionized water, ozone, oxygen, and hydrogen peroxide. Further preferably, the transition metal zinc precursor is diethyl zinc, the aluminum precursor is trimethyl aluminum, and the oxygen precursor is deionized water.
[0021] Further, the transition metal zinc precursor is one of dimethyl zinc, diethyl zinc, zinc acetylacetonate complex, zinc chloride, and zinc methoxide compound; the boron precursor is one of trimethyl boron, boron trichloride, triethyl boron, boric acid, isopropyl borate, and boron oxide compound; and the oxygen precursor is one of deionized water, ozone, oxygen, and hydrogen peroxide. More preferably, the transition metal zinc precursor is diethyl zinc, the boron precursor is isopropyl borate, and the oxygen precursor is deionized water.
[0022] Preferably, n is any integer from 3 to 50, and N is any integer from 1 to 54. More preferably, the number of cycles n is 5, and the number of large cycles N is 10.
[0023] Further, in step S4, the process of preparing the alumina capping layer is as follows: After the deposition of AZO or BZO, the chamber is evacuated for 1 minute, the chamber is heated to 100 - 300 °C, and 100 - 800 cycles of growth of the metal aluminum precursor and the oxygen precursor are carried out to obtain an alumina capping layer with a thickness of 10 nm - 80 nm.
[0024] Further, in step S5, the annealing process is as follows: The sliced solar cell with the SiO x / AZO / Al2O3 or SiO x / BZO / Al2O3 edge passivation stack layer is annealed under the conditions that the annealing atmosphere is formed by N2 and H2 with a volume ratio of 95%:5%, the annealing temperature is 500 °C, and the annealing time is 30 minutes.
[0025] Compared with the prior art, by forming an SiO x / AZO / Al2O3 or SiO x / BZO / Al2O3 edge passivation stack layer on the cutting edge of the sliced solar cell, the chemical passivation and field effect passivation performance of the sliced solar cell are improved, and the repair of the laser cutting edge damage of the TOPCon solar cell / BC cell is realized. Description of the Drawings
[0026] Figure 1 It is a laser cutting method for a silicon-based solar cell.
[0027] Figure 2 It is a schematic structural diagram of an edge passivated sliced solar cell. Detailed Embodiments
[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.
[0029] Example 1
[0030] In this example, silicon oxide is grown by ultraviolet ozone, boron zinc oxide (BZO) is grown by atomic layer deposition, and aluminum oxide (AlO) is grown. x Finally, SiO x / BZO / AlO x A method for passivating the edge of a diffused n-type TOPCon solar cell with a size of 166×166 cm and a thickness of 150 μm, comprising the following steps: 2 1) Laser cutting of the TOPCon solar cell: The structure of the TOPCon solar cell in this example is as
[0031] shown, including an n-type monocrystalline silicon substrate 10. On the upper end face of the n-type monocrystalline silicon substrate 10, there are successively arranged a boron-doped emitter layer 11, an aluminum oxide layer 12, a silicon nitride layer 13, and a front metal electrode 14 from bottom to top; on the lower end face of the n-type monocrystalline silicon substrate 10, there are successively arranged a silicon oxide layer 21, a phosphorus-doped polysilicon layer 22, a silicon nitride layer 23, and a back metal electrode 24 from bottom to top; The laser cutting method of the solar cell is as Figure 2 shown. The dissociation is carried out by laser cutting, and the sizes are respectively cut to 1 / 2 and 1 / 4 of the original wafer; Figure 1 2) After each laser cutting, a solar cell IV tester is used to test the optoelectronic parameters, especially the optoelectronic conversion efficiency.
[0032] 3) Growth of silicon oxide by ultraviolet ozone: The sliced solar cells after different cutting times are placed in the cavity of an ultraviolet ozone cleaning machine. By heating the substrate temperature to 50 °C and the ozone treatment time is 5 min, a 1.5 nm thick silicon oxide layer is generated at the edge of the dissociated cell;
[0033] 4) Atomic layer deposition of zinc oxide thin film: The sliced solar cells after growing silicon oxide are placed in the ALD cavity. The mechanical pump is turned on, and the vacuum is pumped to below 5E-2 torr. Pure ZnO
[0034] thin film is grown through n cycles of diethylzinc and deionized water precursors, and 10 cycles of intrinsic zinc oxide thin film are deposited and fixed; x 5) Boron doping treatment: After depositing the fixed 10 cycles of intrinsic zinc oxide thin film, a boron doping treatment is carried out. At this time, the boron metal precursor is isopropyl borate, and the pulse time of the boron metal precursor is 80 ms. Taking 10 depositions of intrinsic zinc oxide plus one deposition of intrinsic boron oxide as one small cycle, and performing 6 large cycles on this small cycle, the total number of cycles is 60 Cycle, and the film thickness is about 6 nm; Boron-doped zinc oxide is grown at the edge of the sliced solar cell;
[0035] 6) Growth of aluminum oxide: After the boron doping treatment, the sliced solar cells are placed in the ALD cavity again, and the mechanical pump is turned on, and the vacuum is pumped to below 5E-2 torr. Aluminum oxide is grown through m cycles of trimethylaluminum and deionized water precursors, and 10 cycles of aluminum oxide thin film are deposited and fixed;
[0036] 6) Atomic layer deposition of aluminum oxide capping layer: Deposit an aluminum oxide thin film by atomic layer deposition. Place the sliced solar cell with BZO grown above in the chamber of the atomic layer deposition equipment heated to 200 °C, evacuate to below 5E-2 torr, deposit an intrinsic zinc oxide thin film with 250 fixed deposition cycles, and the thickness is about 27 nm; grow an intrinsic aluminum oxide capping layer at the edge of the sliced solar cell.
[0037] Post-annealing treatment: Place the sliced solar cell with the deposited SiO x / AZO / AlO x thin film in an annealing atmosphere of a nitrogen-hydrogen mixture (N2:H2 = 95%:5%), an annealing temperature of 500 °C, and an annealing time of 30 minutes to obtain the sliced solar cell sample 1 with passivated cutting edges.
[0038] Example 2
[0039] In this example, silicon oxide is grown by oxygen plasma, AZO is grown by atomic layer deposition, and AlO x is grown, and finally SiO x / AZO / AlO x passivated slices of 166×166 cm 2 , a method for the edge of an n-type TOPCon solar cell with a thickness of 150 μm, includes the following steps:
[0040] 1) Laser cutting of TOPCon solar cell: The structure of the TOPCon solar cell in this example is as Figure 2 shown, including an n-type single-crystalline silicon substrate 10. On the upper end face of the n-type single-crystalline silicon substrate 10, there are successively a boron-doped emitter layer 11, an aluminum oxide layer 12, a silicon nitride layer 13, and a front metal electrode 14 from bottom to top; on the lower end face of the n-type single-crystalline silicon substrate 10, there are successively a silicon oxide layer 21, a phosphorus-doped polysilicon layer 22, a silicon nitride layer 23, and a back metal electrode 24 from bottom to top; the laser cutting method of the solar cell is as Figure 1 shown, and dissociation is carried out by laser cutting. After each laser cutting, the photovoltaic parameters of the solar cell are tested using a solar cell IV tester, especially the photovoltaic conversion efficiency.
[0041] 2) Oxygen plasma treatment to grow silicon oxide: Place the sliced solar cells with different cutting times into the PEALD chamber, turn on the mechanical pump, evacuate to below 5E-2 torr, heat the substrate temperature to 200 °C. At this time, introduce 50 sccm of oxygen, the plasma power is 80 W, and the plasma treatment time is 4 s to generate a 1-nm-thick silicon oxide layer, and grow silicon oxide at the edge of the sliced solar cell;
[0042] 3) Atomic layer deposition of zinc oxide thin film: Place the sliced solar cell with silicon oxide grown by oxygen plasma into the PEALD chamber and wait for the vacuum to reach below 5E-2 torr. Grow pure ZnO through 5 cycles of diethylzinc and deionized water precursor circulation. x Deposit the intrinsic zinc oxide thin film with 5 fixed deposition cycles.
[0043] 4) Aluminum doping treatment: After depositing the fixed 5-cycle intrinsic zinc oxide thin film, perform an aluminum doping treatment. At this time, the aluminum metal precursor is trimethylaluminum, and the pulse time of the aluminum metal precursor is 70 ms. Take the deposition of 5 times of intrinsic zinc oxide plus 1 time of intrinsic aluminum oxide as a small cycle, and perform 20 large cycles on this small cycle. The total number of cycles is 100 Cycle, and the film thickness is about 18 nm; grow aluminum-doped zinc oxide at the edge of the sliced solar cell.
[0044] 5) Atomic layer deposition of alumina capping layer: Deposit the alumina thin film by atomic layer deposition. Place the silicon wafer with AZO grown above in the PEALD chamber heated to 200 degrees Celsius and wait for the vacuum to reach below 5E-2 torr. Deposit the intrinsic zinc oxide thin film with 250 fixed deposition cycles, and the thickness is about 27 nm; grow the intrinsic alumina capping layer at the edge of the sliced solar cell.
[0045] Post-annealing treatment: Anneal the sliced solar cell with the above-deposited SiO x / BZO / AlO x thin film under the conditions of an annealing atmosphere of nitrogen-hydrogen mixture (N2:H2 = 95%:5%), an annealing temperature of 500 degrees Celsius, and an annealing time of 30 minutes to obtain the sliced solar cell sample 2 with passivated cutting edges.
[0046] Use a solar cell IV test equipment (Vision vs6825, Class AAA light source) to perform photoelectric efficiency tests on the TOPCon sliced cell before cutting, the sliced solar cell after cutting, the sliced solar cell sample 1 with passivated cutting edges, and the sliced solar cell sample 2 with passivated cutting edges respectively. The test results are shown in Table 1.
[0047] Table 1
[0048]
[0049] As can be seen from Table 1, the greater the number of laser cutting times, the greater the efficiency decay. After passivating the edges with SiO x / AZO / Al2O3 and SiO x / BZO / Al2O3, the efficiency has increased. SiO x / AZO / AlO xThe passivation edge effect is better.
[0050] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.
Claims
1. A method for passivating the cut edge of a silicon-based solar cell, characterized in that: The following steps are involved: S1, laser cutting silicon-based solar cells into sliced solar cells; S2, subjecting the sliced solar cells to ultraviolet ozone treatment or oxygen plasma treatment to generate a silicon oxide layer on the cut edges of the sliced solar cells; S3, placing the sliced solar cell into an atomic layer deposition chamber, and forming an aluminum-doped zinc oxide (AZO) layer or a boron-doped zinc oxide (BZO) layer outside the silicon oxide layer at the cut edge of the sliced solar cell; S4, placing the sliced solar cell into an atomic layer deposition chamber, and forming an aluminum oxide capping layer outside the aluminum-doped zinc oxide layer or the boron-doped zinc oxide layer at the cut edge of the sliced solar cell; Finally, SiO is formed on the cutting edge of the sliced solar cell. x / AZO / Al2O3 or SiO x / BZO / Al2O3 edge passivation stacking layer; S5, will form SiO x / AZO / Al2O3 or SiO x The sliced solar cells with edge passivation stack of / BZO / Al2O3 were annealed to activate the chemical passivation of hydrogen.
2. The method for passivating the cut edge of a silicon-based solar cell according to claim 1, characterized in that: In step S2, the temperature of the ultraviolet ozone treatment is 25-200° C., and the time is 10-600 seconds.
3. The method for passivating the cut edge of a silicon-based solar cell according to claim 1, characterized in that: In step S2, the process of oxygen plasma treatment is as follows: heating the cavity, placing the sliced solar cell into the cavity, evacuating the back side, evacuating to a vacuum degree lower than 5E-2torr, and performing oxygen plasma treatment on the sliced solar cell. The oxygen plasma treatment time is 1s-20s, the oxygen plasma treatment power is 20-250W, the oxygen flow rate is 25-200sccm, and a silicon oxide layer with a thickness of 0.5nm-3nm is produced.
4. The method for passivating the cut edge of a silicon-based solar cell according to claim 1, characterized in that: In step S3, the preparation process of the aluminum-doped zinc oxide AZO layer is as follows: (1) Using a plug-in fixture to fix the sliced solar cell so as to vertically place the sliced solar cell into an atomic layer deposition chamber, wherein the exposed portion of the sliced solar cell is the cut edge of the sliced solar cell; (2) The chamber is heated to 100-300° C., and a mechanical pump is turned on to evacuate the chamber to a vacuum degree lower than 5E-2 torr; firstly, a transition metal zinc precursor and an oxygen precursor are cyclically grown to form a zinc oxide layer outside the silicon oxide layer for n times, and then an aluminum precursor and an oxygen precursor are cyclically grown to form an aluminum oxide layer outside the zinc oxide layer; or firstly, an aluminum precursor and an oxygen precursor are cyclically grown to form an aluminum oxide layer outside the zinc oxide layer, and then n transition metal zinc precursors are cyclically grown to form a zinc oxide layer outside the silicon oxide layer for n times, which is a small cycle; and N small cycles are performed to obtain an aluminum-doped zinc oxide AZO layer with a thickness of 2nm-30nm.
5. The method for passivating the cut edge of a silicon-based solar cell according to claim 1, characterized in that: In step S3, the preparation process of the boron-doped zinc oxide BZO layer is as follows: 1) Using a plug-in fixture to fix the sliced solar cell so as to vertically place the sliced solar cell into an atomic layer deposition chamber, wherein the exposed portion of the sliced solar cell is the cut edge of the sliced solar cell; 2) The cavity is heated to 100-300° C., and a mechanical pump is turned on to evacuate the cavity to a vacuum degree lower than 5E-2 torr; firstly, a transition metal zinc precursor and an oxygen precursor are cyclically grown to form a zinc oxide layer outside the silicon oxide layer for n times, and then a boron precursor and an oxygen precursor are cyclically grown to form a boron oxide layer outside the zinc oxide layer; or firstly, a boron precursor and an oxygen precursor are cyclically grown to form a boron oxide layer outside the zinc oxide layer, and then n transition metal zinc precursors are cyclically grown to form a zinc oxide layer outside the silicon oxide layer for n times, which is a small cycle; and N small cycles are performed to obtain a boron-doped zinc oxide BZO layer with a thickness of 2nm-15nm.
6. The method for passivating the cut edge of a silicon-based solar cell according to claim 4, characterized in that: The transition metal zinc precursor is one of dimethyl zinc, diethyl zinc, zinc acetylacetonate complex, zinc chloride and zinc methoxy compound, the aluminum precursor is one of trimethyl aluminum, triethyl aluminum, aluminum chloride, isopropoxy aluminum, diisopropyl acetylacetonate aluminum and aluminum trifluoride, and the oxygen precursor is one of deionized water, ozone, oxygen and hydrogen peroxide.
7. The method for passivating the cut edge of a silicon-based solar cell according to claim 5, characterized in that: The transition metal zinc precursor is one of dimethyl zinc, diethyl zinc, zinc acetylacetone complex, zinc chloride and zinc methoxy compound, the boron precursor is one of trimethyl boron, boron trichloride, triethyl boron, boric acid, isopropyl borate and boron oxide compound, and the oxygen precursor is one of deionized water, ozone, oxygen and hydrogen peroxide.
8. The method for passivating the cut edge of a silicon-based solar cell according to claim 4 or 5, characterized in that: The n is any integer from 3 to 50, and N is any integer from 1 to 54.
9. The method for passivating the cut edge of a silicon-based solar cell according to claim 6, characterized in that: In step S4, the preparation process of the aluminum oxide capping layer is as follows: after the AZO or BZO deposition, the chamber is evacuated for 1 minute, the chamber is heated to 100-300° C., and the metal aluminum precursor and the oxygen precursor are cyclically grown 100-800 times to obtain an aluminum oxide capping layer with a thickness of 10nm-80nm.
10. The method for passivating the cut edge of a silicon-based solar cell according to claim 1, characterized in that: In step S5, the annealing process is as follows: x / AZO / Al2O3 or SiO x The sliced solar cell with / BZO / Al2O3 edge passivation stack layer was annealed in an annealing atmosphere formed by N2 and H2 with a volume ratio of 95%:5%, an annealing temperature of 500°C, and an annealing time of 30 minutes.