Photovoltaic monocrystalline silicon wafer and solar cell comprising same

Abstract

A photovoltaic monocrystalline silicon wafer and a solar cell comprising same, belonging to the technical field of solar cells, and in particular to the technical field of photovoltaic silicon wafers. The resistivity of the silicon wafer is 50-500 Ω•cm; and the oxygen content of the silicon wafer is less than or equal to 8x1017 atom / cm3, preferably 1.5×1017-6×1017 atom / cm3. Solar cells manufactured from the silicon wafer have high consistency in photoelectric conversion efficiency.

Description

A photovoltaic monocrystalline silicon wafer and a solar cell comprising the same TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to the technical field of photovoltaic silicon wafers, and more particularly to a photovoltaic monocrystalline silicon wafer and a solar cell comprising the same. BACKGROUND

[0002] Crystalline silicon solar cells have become the dominant product of photovoltaic cells, among which the use of monocrystalline silicon wafers as the substrate of solar cells has made outstanding contributions to further improving the photoelectric conversion efficiency of solar cells. With the progress of the surface passivation technology of photovoltaic cells, the surface recombination of photovoltaic cells is becoming lower and lower. With the decrease of surface recombination, the cell end tends to a higher range of silicon wafer resistivity. For high-efficiency cells (especially high-efficiency cells with an average conversion efficiency of more than 26% in mass production), the cell end requires silicon wafers with ultra-high resistance.

[0003] Generally, after production, the silicon wafers need to be sorted by a sorting machine to supply the silicon wafers meeting the resistance value range required by the cell end to the cell end. However, after the silicon wafers with a resistance value greater than 10Ω·cm are put into the cell end, the concentration of the photoelectric conversion efficiency of the cell end is poor, which is not conducive to quality control. SUMMARY

[0004] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present application provides a photovoltaic monocrystalline silicon wafer and a solar cell comprising the same.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] According to an embodiment of one aspect of the present application, a photovoltaic monocrystalline silicon wafer is provided, the resistivity of the silicon wafer being 50-500Ω·cm; the oxygen content of the above-mentioned silicon wafer being less than or equal to 8×10 17 atom / cm 3 , preferably 1.5×10 17 -6×10 17 atom / cm 3 .

[0007] According to an embodiment of another aspect of the present application, a solar cell is also provided, the substrate of the solar cell being the above-mentioned silicon wafer.

[0008] The silicon wafer provided by the present application has high consistency of photoelectric conversion efficiency of the cell after being made into a solar cell. At the same time, the oxygen content in the above-mentioned range helps to increase the mechanical strength of the silicon wafer, so as to avoid easy warping deformation and fragmentation in the cell process. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0010] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components. All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0011] Crystalline silicon solar cells have become the dominant product in photovoltaic (PV) cells. Among them, using monocrystalline silicon wafers as the substrate for solar cells has made a significant contribution to further improving the photoelectric conversion efficiency of solar cells. With advancements in PV cell surface passivation technology, surface recombination in PV cells is decreasing. As surface recombination decreases, the resistivity range of silicon wafers at the cell end is trending towards higher values. For example, for high-efficiency cells (especially mass-produced high-efficiency cells with an average conversion efficiency greater than 26%), the requirements for silicon wafers at the cell end are trending towards ultra-high resistivity wafers. Many cell manufacturers have already expressed a demand for silicon wafer resistivity greater than 10 Ω·cm.

[0012] Generally, after silicon wafers are produced, they need to be sorted by a sorting machine to supply wafers with resistance values ​​that meet the requirements of the battery. However, when silicon wafers with resistance values ​​greater than 10 Ω·cm are fed into the battery, the concentration of photoelectric conversion efficiency at the battery is poor, which is not conducive to quality control.

[0013] The inventors of this application further discovered that the reason for the poor concentration of photoelectric conversion efficiency at the battery terminal may be:

[0014] Generally, when resistivity is low, the content of dopants in silicon wafers is high, and the dopants dominate, while the influence of other elements or defects is relatively small. Silicon wafers with the same resistivity have more similar properties. However, when resistivity is greater than 10 Ω·cm, especially 50 Ω·cm, the content of dopants in silicon wafers is low, and the influence of dopants is significantly reduced. Meanwhile, the influence of other elements or defects in the silicon wafer is amplified. When the silicon wafer is made into a cell, these effects are released. In particular, the efficiency of cells made from silicon wafers with high element content or many defects drops significantly compared to the target efficiency, resulting in poor concentration of photoelectric conversion efficiency.

[0015] It is found by further research that, when the resistivity is greater than or equal to 50 Ω·cm, the difference in oxygen content has a greater impact on the battery process under the same resistivity. On the one hand, oxygen can cause micro-defects, increase the defects in the silicon wafer, and thus reduce the photoelectric conversion efficiency of the battery; on the other hand, due to the thermal history of the silicon wafer process, oxygen has an oxygen donor effect on the resistivity test of the silicon wafer, which weakens the link between the resistivity tested by the sorting machine and the quality of the silicon wafer. Even if the resistivity is the same, the quality of the silicon wafer is quite different, and the difference is reflected after the battery process, that is, the photoelectric conversion efficiency is concentrated.

[0016] The inventors of the present application find that, when the resistivity of the silicon wafer is 50-500 Ω·cm, the oxygen content is less than 8×10 17 atom / cm 3 , the micro-defects caused by oxygen in the silicon wafer are controlled within a certain range; and when the oxygen content is within this range, the link between the resistivity and the quality of the silicon wafer is relatively strong, and the photoelectric conversion efficiency of the battery is more concentrated.

[0017] Specifically, according to an embodiment of one aspect of the present application, a photovoltaic monocrystalline silicon wafer is provided, the resistivity of the silicon wafer is 50-500 Ω·cm; and the oxygen content of the silicon wafer is less than or equal to 8×10 17 atom / cm 3 .

[0018] According to the embodiments of the present application, the photovoltaic silicon wafer provided by the present application is mainly applied to solar cells, and the purity requirement is lower than that of semiconductor silicon wafers applied to semiconductor devices, and there are also great differences in shape and size. The photovoltaic silicon wafer of the present application is a high-resistance silicon wafer, that is, the doping concentration is small, and compared with low-resistance silicon wafers, lattice distortion does not occur in the crystal growth process due to the difference in atomic radius, which reduces the breakage rate in the crystal pulling process. At the same time, due to the low content of doped impurities and few defects, it is beneficial to improve the minority carrier lifetime. The resistivity of the silicon wafer provided by the present application can be 50 Ω·cm, 100 Ω·cm, 200 Ω·cm, 250 Ω·cm, 300 Ω·cm, 350 Ω·cm, 400 Ω·cm, 450 Ω·cm or 500 Ω·cm.

[0019] In one embodiment, the silicon wafer provided by the present application is a monocrystalline silicon wafer, which has a complete lattice structure and a stronger carrier conduction capability, which helps to improve the photoelectric conversion efficiency.

[0020] The present application does not make special limitations on the conductivity type of the silicon wafer, and the conductivity type can be N-type or P-type, and more preferably an N-type monocrystalline silicon wafer.

[0021] According to embodiments of this application, the oxygen content of the silicon wafer provided in this application refers to the total oxygen content, that is, the total oxygen content in general. Total oxygen includes oxygen donors, interstitial oxygen, and precipitated oxygen. Typically, oxygen in silicon wafers exists primarily as interstitial oxygen. The oxygen content in this application can be 1×10⁻⁶. 17 atom / cm 3 1.5×10 17 atom / cm 3 2×10 17 atom / cm 3 3×10 17 atom / cm 3 4×10 17 atom / cm 3 5×10 17 atom / cm 3 6×10 17 atom / cm 3 7×10 17 atom / cm 3 Or 8×10 17 atom / cm 3 The oxygen content is further preferably 1.5 × 10⁻⁶. 17 -6×10 17 atom / cm 3 .

[0022] In this application, the total oxygen content in the silicon wafer can be detected by any method known to those skilled in the art, and they can choose the appropriate method based on their needs, such as secondary ion mass spectrometry (SIMS). In one specific embodiment of this application, secondary ion mass spectrometry (SIMS) is used to test the total oxygen content of the silicon wafer. Those skilled in the art will understand that the total oxygen content in the silicon wafer can refer to the total oxygen content at any point on the surface of the silicon wafer, in the middle of the silicon wafer, or it can be the average of the total oxygen content at multiple locations or the average of the total oxygen content across the entire silicon wafer. Those skilled in the art can select any of the above-mentioned locations for detection based on the detection conditions and the instruments used, or they can detect multiple locations and calculate the average of the multiple locations as the total oxygen content detection result of the silicon wafer.

[0023] In a preferred embodiment, the oxygen donor content in the silicon wafer is less than or equal to 3 × 10⁻⁶. 14 atom / cm 3 Preferably less than or equal to 8.59 × 10 13 atom / cm 3 More preferably, it is 1.42 × 10 13 -5×10 13 atom / cm 3 .

[0024] According to the embodiments of the present application, the content of the oxygen donor can be 1×10 13 atom / cm 3 , 1.42×10 13 atom / cm 3 , 2×10 13 atom / cm 3 , 3×10 13 atom / cm 3 , 4×10 13 atom / cm 3 , 5×10 13 atom / cm 3 , 6×10 13 atom / cm 3 , 7×10 13 atom / cm 3 , 8×10 13 atom / cm 3 , 8.59×10 13 atom / cm 3 , 9×10 13 atom / cm 3 , 1×10 14 atom / cm 3 , 2×10 14 atom / cm 3 , 2.8×10 14 atom / cm 3 , or 3×10 14 atom / cm 3 .

[0025] It is found through experiments that the content of the above oxygen donor can further reduce the influence of the oxygen donor on the resistance uniformity of the silicon wafer, and the silicon wafers with the same resistance sorted have good photoelectric conversion efficiency concentration at the battery end. Especially when the content of the oxygen donor is less than 5×10 13 atom / cm 3 , the influence on the resistance variation of the 50-500Ω·cm high resistance silicon wafer is smaller, and it is more conducive to improving the concentration of the photoelectric conversion efficiency at the battery end.

[0026] Exemplarily, the determination of the content of the oxygen donor can be determined by the following way: first, the four-probe method is used to detect the resistance value ρ1 of the silicon wafer, then the silicon wafer is annealed at 650℃ for 1h (which can make the oxygen donor completely disappear), the four-probe method is used to detect the resistance value ρ2 of the silicon wafer after annealing, and finally the content N A of the oxygen donor is calculated based on the two resistance values ρ1 and ρ2.

[0027] In a preferred embodiment, the content of interstitial oxygen in the silicon wafer is less than 6 x 10 17 atom / cm 3 , preferably 3 x 10 17 - 5 x 10 17 atom / cm 3 .

[0028] According to embodiments of the present application, the content of interstitial oxygen can be 1 x 10 17 atom / cm 3 , 2 x 10 17 atom / cm 3 , 3 x 10 17 atom / cm 3 , 4 x 10 17 atom / cm 3 , 4.5 x 10 17 atom / cm 3 , 5 x 10 17 atom / cm 3 , 5.5 x 10 17 atom / cm 3 , or 6 x 10 17 atom / cm 3 .

[0029] The inventors of the present application, through a large number of experiments and data research, fit the content of interstitial oxygen and oxygen donor concentration, when the content of interstitial oxygen is less than or equal to 6 x 10 17 atom / cm 3 , the oxygen donor concentration is less than or equal to 3 x 10 14 atom / cm 3 , thereby reducing the influence of oxygen donors on high resistance silicon wafers, thereby improving the concentration of cell end photoelectric conversion rate.

[0030] Further, when the content of interstitial oxygen is less than 8 ppma, i.e. in the range of 4 x 10 17 atom / cm 3 , the change of oxygen donors is relatively flat, thereby making the photoelectric conversion efficiency of the cell high at the same resistivity.

[0031] The interstitial oxygen content of the silicon wafer can be detected by any method known to those skilled in the art, which can be selected by those skilled in the art based on the requirements, for example, can be detected by a Fourier infrared spectrometer. In this application, in one specific manner, the Fourier infrared spectrometer is used to test the interstitial oxygen content of the silicon wafer. Those skilled in the art can understand that the interstitial oxygen content in the silicon wafer can refer to the interstitial oxygen content at any site on the surface of the silicon wafer, the middle of the silicon wafer, or the average of the interstitial oxygen content at multiple positions or the average of the interstitial oxygen content on the entire silicon wafer or silicon substrate. Those skilled in the art can select the above-mentioned any site for detection based on the detection conditions and the instrument used, or can detect multiple sites and calculate the average of multiple sites as the detection result of the interstitial oxygen content of the silicon wafer.

[0032] In a preferred embodiment, the content of precipitated oxygen in the silicon wafer can be less than or equal to 3×10 17 atom / cm 3 , preferably less than or equal to 1.2×10 17 atom / cm 3 .

[0033] According to the embodiments of the present application, the content of precipitated oxygen can be 1×10 17 atom / cm 3 , 1.2×10 17 atom / cm 3 , 1.5×10 17 atom / cm 3 , 2×10 17 atom / cm 3 , 2.5×10 17 atom / cm 3 or 3×10 17 atom / cm 3 .

[0034] When the content of precipitated oxygen is in the above range, the defects caused by precipitated oxygen are smaller, and the quality of the silicon wafer is higher, thereby improving the concentration of the cell end photoelectric conversion rate.

[0035] The content of precipitated oxygen in the silicon wafer can be obtained by calculation, and the content of precipitated oxygen can be determined according to the difference between the oxygen content and the interstitial oxygen content and the oxygen donor content.

[0036] According to the embodiments of the present application, the silicon wafer contains a third and / or fifth main group of doping elements, and the doping elements are selected from one or more of phosphorus, gallium, arsenic, and antimony; wherein the total concentration of the doping elements is 1×10 12 -3×10 14 atom / cm 3 .

[0037] According to embodiments of the present application, the sum of the concentrations of the doped elements can be 1 x 10 12 atom / cm 3 , 2 x 10 12 atom / cm 3 , 5 x 10 12 atom / cm 3 , 8 x 10 12 atom / cm 3 , 1 x 10 13 atom / cm 3 , 3 x 10 13 atom / cm 3 , 5 x 10 13 atom / cm 3 , 8 x 10 13 atom / cm 3 , 1 x 10 14 atom / cm 3 , 2 x 10 14 atom / cm 3 , or 3 x 10 14 atom / cm 3 .

[0038] In a silicon wafer, the fifth main group element can provide electrons, and the oxygen donor can also provide electrons, and the final product resistivity is determined by the combined effect of the fifth main group element doping concentration and the oxygen donor concentration. The lower the oxygen donor concentration, the closer the resistivity of the silicon wafer to the resistivity provided by the fifth main group doping element. Similarly, the third main group element can provide holes, and the oxygen donor can provide electrons, and the final product resistivity is determined by the combined effect of the third main group element doping concentration and the oxygen donor concentration. The lower the oxygen donor concentration, the closer the resistivity of the silicon wafer to the resistivity provided by the third main group doping element. When the content of the doped element is low, the oxygen content should be less than 8 x 10 17 atom / cm 3 , so that the cell concentration is higher at the same resistivity.

[0039] In a preferred embodiment, the sum of the concentrations of the transition metals is less than or equal to 5 ng / g, and the sum of the concentrations of the transition metals can be 1 ng / g, 2 ng / g, 3 ng / g, 4 ng / g, or 5 ng / g.

[0040] The above-mentioned low content of transition metals has a small probability of interaction with oxygen, and the transition metals cause less deep level defects, which is beneficial to improve the minority carrier lifetime and the quality of the silicon wafer.

[0041] In a preferred embodiment, the minority carrier lifetime of the silicon wafer is greater than 2000 μs. For example, the minority carrier lifetime of the silicon wafer can be 2500 μs, 3500 μs, 4000 μs, 4500 μs, 5000 μs or 6000 μs. A higher minority carrier lifetime in the silicon wafer means that there are fewer defects in the silicon wafer, which means that the silicon wafer has a higher quality and is more conducive to improving the photoelectric conversion efficiency of the solar cell.

[0042] According to embodiments of the present application, the silicon wafer can be rectangular, square or circular, etc., so as to be more conveniently used as a substrate in a solar cell. Preferably, the silicon wafer is rectangular or square, because it has a larger use area, which is conducive to improving the power of the solar cell.

[0043] According to embodiments of the present application, the side length of the silicon wafer can be greater than 75 mm, for example, it can be 156 mm, 166 mm, 182 mm, 210 mm, 218 mm or 245 mm. It should be noted that when the silicon wafer is square, the side length is the length of a side of the square. When the silicon wafer is rectangular, the side length here can be the length of any side of the rectangle. A suitable size of the silicon wafer is conducive to improving the use area, so that the power of the solar cell can be increased.

[0044] According to embodiments of the present application, the silicon wafer also has a chamfer, and the projection length of the arc length corresponding to the chamfer of the silicon wafer is 1 mm to 10 mm, for example, it can be 1 mm, 2 mm, 4 mm, 6 mm, 8 mm or 10 mm. Under the same size of the silicon wafer, a suitable projection length of the arc length is conducive to smoothing the edge of the silicon wafer and improving the processing quality, while helping to obtain a suitable use area, so as to help improve the power of the solar cell.

[0045] For the silicon wafer of the present application, a person skilled in the art can obtain the approximate target resistivity by a resistivity control method known in the art, and obtain the approximate target oxygen content by an oxygen control method known in the art. Then, the silicon wafer with the target resistivity and the target oxygen content is obtained by sorting.

[0046] For example, in the process of pulling a single crystal silicon rod from a silicon melt by using the Czochralski method, the oxygen content is controlled in the required range, and the oxygen content of the single crystal silicon rod is controlled in the above range by at least one of the following methods 1 to 4.

[0047] In method 1, a hook-shaped magnetic field with a magnetic field strength of 1000-5000 Gauss is used. The hook-shaped magnetic field is a non-uniform magnetic field, which can suppress the thermal convection of the silicon melt in the crucible. Increasing the magnetic field strength can reduce the oxygen concentration at the solid-liquid interface during the growth of large-size crystals, and at the same time, it is conducive to improving the uniformity of the oxygen concentration distribution at the solid-liquid interface.

[0048] Optionally, the growth of the single crystal silicon rod is completed in a single crystal furnace, the single crystal furnace is provided with a quartz crucible, and the single crystal furnace is provided with a magnetic field generator. By applying a hook-shaped magnetic field to the silicon melt in the crucible through the magnetic field generator, the oxygen content in the silicon melt can be reduced, thereby reducing the oxygen content in the single crystal silicon rod drawn from the silicon melt.

[0049] In mode 2, the silicon melt is heated using an oxygen-reducing heater; the oxygen-reducing heater can suppress the oxygen impurities in the silicon melt by optimizing the dynamic and static thermal field, intelligently controlling the thermal field temperature, improving the furnace body impurity removal capacity, realizing the upgrading of the oxygen-reducing effect, and improving the overall quality of the crystal.

[0050] Optionally, for example, a shortened side heater height can be used to reduce the high-temperature area of the crucible, thereby weakening the precipitation of oxygen atoms in the crucible.

[0051] In mode 3, the pulling speed of the single crystal silicon rod in the constant diameter growth stage is controlled to be 89-90 mm / h at the head and 110-120 mm / h at the tail; by controlling the pulling speed of the crystal rod head and tail, the thermal history process of the crystal rod is controlled to regulate the oxygen content and reduce the oxygen donor content, so that the oxygen donor content at different positions of the whole crystal rod is controlled within the target range.

[0052] In mode 4, the pressure in the furnace is controlled to be maintained at 50-600 Pa. Generally, the lower the furnace pressure, the lower the oxygen content in the single crystal silicon, and the higher the furnace pressure, the higher the oxygen content in the single crystal silicon. The oxygen content of the single crystal silicon can be controlled by controlling the pressure in the furnace.

[0053] According to an embodiment of another aspect of the present application, a solar cell is also provided, and the substrate of the solar cell is the silicon wafer of any of the above embodiments.

[0054] According to an embodiment of the present application, in a solar cell, the silicon wafer provided by the present application is used, so that the photoelectric conversion efficiency of the cell is high.

[0055] According to an embodiment of the present application, the above-mentioned silicon wafer can be applied to various battery types, such as: tunnel oxide passivation contact battery (TOPcon), double-sided heterojunction battery (Heterojunction with Intrinsic Thin-layer, referred to as HJT), tunnel passivation contact back contact battery (TBC), heterojunction back contact battery (Heterojunction Back Contac, referred to as HBC), hybrid HBC battery (such as a hybrid battery combined with TBC (TopCon-Back Contact)-HJT), etc.

[0056] More preferably, the battery is a TBC battery.

[0057] The application will be further described in conjunction with specific examples.

[0058] Example 1

[0059] The silicon wafers with resistivity of 50±1 Ω·cm, oxygen content of 8*10 17 atom / cm 3 , and metal impurity concentration of 1*10 16 atom / cm 3 were selected, and 10,000 wafers were put into the battery TBC production line. The battery yield was recorded, and the details are shown in the following table.

[0060] Example 2

[0061] The difference from Example 1 is that the resistivity of the silicon wafer is 50±1 Ω·cm, and the oxygen content is 7.5*10 17 atom / cm 3 .

[0062] Example 3

[0063] The difference from Example 1 is that the resistivity of the silicon wafer is 100±1 Ω·cm, and the oxygen content is 6*10 17 atom / cm 3 .

[0064] Example 4

[0065] The difference from Example 1 is that the resistivity of the silicon wafer is 120±1 Ω·cm, and the oxygen content is 4*10 17 atom / cm 3

[0066] Example 5

[0067] The difference from Example 1 is that the resistivity of the silicon wafer is 160±1 Ω·cm, and the oxygen content is 1.5*10 17 atom / cm 3 .

[0068] Example 6

[0069] The difference from Example 1 is that the resistivity of the silicon wafer is 160±1 Ω·cm, and the oxygen content is 1*10 17 atom / cm 3 .

[0070] Example 7

[0071] The difference from Example 1 is that the resistivity of the silicon wafer is 500±1 Ω·cm, and the oxygen content is 3*10 17 atom / cm 3 .

[0072] Comparative Example 1

[0073] The difference from Example 1 is that the silicon wafer resistivity is 1±1 Ω-cm, and the oxygen content is 8*10 17 atom / cm 3 .

[0074] Comparative Example 2

[0075] The difference from Example 1 is that the silicon wafer resistivity is 30±1 Ω-cm, and the oxygen content is 7*10 17 atom / cm 3 .

[0076] Comparative Example 3

[0077] The difference from Example 1 is that the silicon wafer resistivity is 50±1 Ω-cm, and the oxygen content is 9.5*10 17 atom / cm 3 .

[0078] The test results are shown in the following table:

[0079] It should be noted that the data in the above table are respectively obtained by testing the efficiency of ten thousand samples in the TBC battery product line corresponding to Examples 1-7, and calculating the battery yield. Among them, the proportion of the corresponding battery with efficiency greater than 26% in ten thousand samples in each example is defined as the battery yield, and the greater the proportion represents the higher the concentration of the battery end photoelectric conversion efficiency.

[0080] As can be seen from the above table, in Examples 1-7, 50 Ω-cm < resistivity < 500 Ω-cm, and the oxygen content < 8*10 17 atom / cm 3 , the battery yield is more than 92%;

[0081] Referring to Comparative Example 1, when the resistivity is 1 Ω-cm, the oxygen content is 8*10 17 atom / cm 3 , the battery yield is only 86%, which is much lower than the 92% in the examples; similarly, referring to Comparative Example 2, when the resistivity is 30 Ω-cm and the oxygen content is 7*10 17 atom / cm 3 , the battery yield is only 89%, which is also much lower than 92%.

[0082] Referring to Comparative Example 3, although the resistivity reaches 50 Ω-cm, the oxygen content is 9.5*10 17 atom / cm 3 , the battery yield is only 70%.

[0083] As can be seen from the above, as long as the resistivity and oxygen content are within the ranges exemplified in the present application, the battery yield, i.e. the proportion of batteries with an efficiency greater than 26%, can be significantly improved, thereby improving the concentration of the battery end photoelectric conversion efficiency. However, as long as the resistivity (such as Comparative Example 1-2) or the oxygen content (Comparative Example 3) is not within the range exemplified in the present application, especially the oxygen content is not within the exemplified range, the battery yield is reduced more.

[0084] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A photovoltaic single crystal silicon wafer, the resistivity of the silicon wafer being 50-500 Ω-cm; the oxygen content of the silicon wafer being less than or equal to 8 x 10 17 atom / cm 3 , preferably 1.5 x 10 17 -6 x 10 17 atom / cm 3 .

2. The silicon wafer of claim 1, wherein, The content of oxygen donors in the silicon wafer is less than or equal to 3 x 1016 atoms / cm2 14 atoms / cm2 3 , preferably less than or equal to 8.59 x 1016 atoms / cm2 13 atoms / cm2 3 , more preferably 1.42 x 1016 atoms / cm2 13 - 5 x 1016 atoms / cm2 13 atoms / cm2 3 .

3. The silicon wafer of claim 1 or 2, wherein, The content of interstitial oxygen in the silicon wafer is less than or equal to 6 x 10 17 atom / cm 3 , preferably 3 x 10 17 - 5 x 10 17 atom / cm 3 .

4. The silicon wafer of claim 1 or 2, wherein, The content of precipitated oxygen in the silicon wafer is less than or equal to 3 x 10 17 atom / cm 3 , preferably less than or equal to 1.2 x 10 17 atom / cm 3 .

5. The silicon wafer of claim 1, wherein, the silicon wafer contains a doping element of the third and / or fifth main group, which is preferably selected from one or more of phosphorus, gallium, arsenic, antimony; wherein the sum of the concentrations of the doping elements is 1 x 10 12 -3 x 10 14 atom / cm 3 .

6. The silicon piece of claim 1 or 2, wherein, the sum of the concentrations of transition metals in the silicon wafer is less than or equal to 5 ng / g.

7. The silicon wafer of claim 1, wherein, the minority carrier lifetime of the silicon wafer is greater than 2000 μs.

8. The silicon wafer of claim 1, wherein, the edge length of the silicon wafer is greater than 75 mm.

9. The silicon wafer of claim 1, wherein, the length of the projection of the arc length of the chamfering of the silicon wafer is from 1 mm to 10 mm.

10. A solar cell, the substrate of which is a silicon wafer according to any one of claims 1 to 9.

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