Solar cell and photovoltaic module

Abstract

The present application provides a solar cell, which comprises: a silicon substrate, and a plurality of collector grid lines formed on a side surface of the silicon substrate; the silicon substrate is doped with antimony elements, the grid line density of collector grid lines of the same polarity per unit length in a direction perpendicular to the collector grid lines is n grid lines / cm, and the concentration of antimony elements in the silicon substrate is a atoms / cm 3 When n and a satisfy the following relationship: n≥35‑klg a Formula 1, wherein k is less than or equal to 2. The present application also provides a photovoltaic module formed by the solar cell of the present application.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module comprising the solar cell. Background Art

[0002] In current silicon solar cells, the substrate usually uses a silicon wafer with an N-type or P-type doped substrate. P-type and N-type semiconductors are formed at different positions of the silicon wafer, and then electrodes are formed on the P-type and N-type semiconductor regions to form a battery. When light is incident on the silicon battery substrate, electron-hole pairs are generated. The free electron-hole pairs are separated by carriers, so that electrons gather near the N pole and holes gather near the P pole. When an external circuit is connected to the electrode, current can be output. In the prior art, a P-type substrate or an N-type substrate is usually used as a photovoltaic semiconductor substrate. The P-type substrate is usually doped with boron or gallium. The N-type substrate is usually doped with phosphorus.

[0003] N-type semiconductor substrates have the advantage of long minority carrier diffusion length. When used in silicon solar cells for power generation, more carriers will be collected compared to P-type substrates, which means they have higher efficiency accordingly. N-type substrates are usually doped with phosphorus. In the photovoltaic field, research has begun on using Sb-doped silicon wafers as silicon substrates to prepare solar cells and photovoltaic modules. However, for solar cells formed by Sb-doped silicon substrates, further optimization is needed to improve cell efficiency. Summary of the invention

[0004] In view of the above problems, this application is intended to improve the problems involved in the above prior art. Through in-depth research, this application confirms the relationship between Sb concentration and grid line density, and realizes that the transmission effect and battery efficiency of solar cells are improved by combining the Sb concentration in the silicon substrate and the number of grid lines. This application provides the following solutions:

[0005] 1. A solar cell, comprising:

[0006] A silicon substrate, and a plurality of collector grid lines formed on a surface of one side of the silicon substrate;

[0007] The silicon substrate is doped with antimony element,

[0008] The density of collector gate lines of the same polarity in a direction perpendicular to the collector gate lines is n / cm, and the concentration of antimony elements in the silicon substrate is a atoms / cm 3 When , n and a satisfy the following relationship:

[0009] n≥35-klg a Formula 1,

[0010] Wherein, k is less than or equal to 2.

[0011] 2. The solar cell according to item 1, wherein when the thickness of the silicon substrate of the cell is b μm, n satisfies the following relationship:

[0012]

[0013] Wherein, c is a constant and its value is 50 μm.

[0014] 3. The solar cell according to item 1, wherein n and a further satisfy the following relationship:

[0015] n≤35-lg a Formula 3.

[0016] 4. The solar cell according to any one of items 1 to 3, wherein the solar cell is a double-sided contact cell, and k=2.

[0017] 5. The solar cell according to any one of items 1 to 3, wherein the solar cell is a back contact cell, and k=1.9.

[0018] 6. The solar cell according to item 5, wherein one side surface of the silicon substrate has an electron collection region and a hole collection region, and an isolation region between the electron collection region and the hole collection region; when the depth of the isolation region is d μm, n satisfies the following relationship:

[0019]

[0020] 8. The solar cell according to item 6, wherein:

[0021] The depth of the isolation region is the numerical height difference corresponding to the average depth of the bottom of the shallower region between the electron collection region and the hole collection region from the bottom of the isolation region, and the bottom of the isolation region is the surface of the silicon substrate corresponding to the isolation region.

[0022] When the solar cell comprises an interface passivation layer, the bottom of the electron collection region or the hole collection region is the height of the interface passivation layer close to the silicon substrate.

[0023] 8. The solar cell according to any one of items 1 to 7, wherein the range of a is 1E13 to 1E18.

[0024] 9. The solar cell according to any one of items 1 to 8, wherein the width of each of the collector grid lines is 10-200 μm.

[0025] 10. A photovoltaic component, characterized in that the photovoltaic component comprises the solar cell described in any one of items 1 to 9.

[0026] Effects of the Invention

[0027] The present application can effectively improve the effect of lateral transmission based on the battery structure, the concentration of the Sb element in the battery silicon substrate, and the number of collector grid lines, that is, it can satisfy the above formula 1. It can obtain good battery efficiency Eta and open circuit voltage, and at the same time, the short circuit current and fill factor are also relatively excellent, that is, it can effectively improve the efficiency of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a back-contact solar cell is shown.

[0029] Figure 2 Shown is the back electrode pattern of a back-contact cell.

[0030] Figure 3 Shows the back electrode pattern of a double-sided contact cell.

[0031] Figure 4 A schematic diagram of a back-contact solar cell according to a specific embodiment of the present application is shown.

[0032] Figure 5 A schematic diagram of a back-contact solar cell according to a specific embodiment of the present application is shown.

[0033] Figure 6 A schematic diagram of a back-contact solar cell according to a specific embodiment of the present application is shown.

[0034] Figure 7 A schematic diagram of a double-sided contact solar cell according to a specific embodiment of the present application is shown.

[0035] Figure 8 The battery efficiency trend graph of Table 1 is shown.

[0036] Fig. 9 The battery efficiency trend graph of Table 2 is shown.

[0037] Fig.10 Table 3 shows the battery efficiency trend graph.

[0038] Fig.11 Table 4 shows the battery efficiency trend graph.

[0039] Fig.12 A schematic diagram showing the fitting curve of antimony doping concentration and inflection point grid line density.

[0040] Explanation of symbols:

[0041] 1: first electrode; 2: passivation layer; 3: semiconductor layer; 9: interface passivation layer; 4: silicon substrate; 5: second electrode; 6: isolation region; 7: hole collection region; 8: electron collection region. DETAILED DESCRIPTION

[0042] The following embodiments of the present application are only used to illustrate the specific embodiments of the present application, and these embodiments cannot be understood as limiting the present application. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present application are deemed to be equivalent replacement methods and fall within the scope of protection of the present application.

[0043] The specific embodiments of the present application will be described in more detail below. However, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to enable the scope of the present application to be fully communicated to those skilled in the art.

[0044] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the implementation of the present application, but the description is based on the general principles of the specification and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0045] As used in this specification, "a" or "an" may mean one or more. As used in the claims, when used with the word "comprising", the word "a" or "an" may mean one or more than one.

[0046] The term "or" is used in the claims to mean "and / or" unless explicitly stated to refer only to alternatives or the alternatives are mutually exclusive, although the present disclosure supports a definition referring only to alternatives and "and / or." As used herein, "another" may mean at least a second or more.

[0047] In the present application, there is no further limitation on the silicon substrate itself involved in the following content of the present application. It can be a silicon substrate (also called a bare silicon wafer) obtained after machining and slicing after the silicon rod is drawn. In the present application, it is also possible to peel and recover a structure containing a silicon substrate and at least a part of the doped area from a battery component, as long as it can have a certain shape and can be presented in a sheet shape, that is, the size of one surface is larger than the size of the surface perpendicular to it, and it is flat or plate-shaped. There is no limitation on the size of the structure containing a silicon substrate body and at least a part of the doped area. The silicon substrate or the silicon substrate containing at least a part of the doped area can be of any size. The silicon substrate body or the silicon substrate body containing at least a part of the doped area after peeling is recovered from the battery component and other layer structures are peeled off. In addition, those skilled in the art can understand that when peeling, if at least a part of the doped area is destroyed, as long as there is still a part of the doped area, it should also be understood to correspond to the solar cell mentioned in the battery of the present application. For example, in a specific embodiment, the length of at least one side of the structure including the silicon substrate body and at least a part of the doped region of the present application is greater than 156 mm, for example, it can be 158±2 mm, (160±2) mm, (165±2) mm, (170±2) mm, (175±2) mm, (180±2) mm, (185±2) mm, 190±2 mm, (195±2) mm, (200±2) mm, (205 In some embodiments, the present invention relates to a silicon substrate or a structure comprising a silicon substrate and at least a portion of a doped region, wherein the thickness of the silicon substrate or the structure comprising the silicon substrate and at least a portion of a doped region is at least 70 to 170 μm, for example, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, or 160 μm. In a specific embodiment, the size of the stripped portion of the other layer structure after recovery and stripping, including the silicon substrate body and at least part of the doped area, can be smaller than the above size, as long as the parameters involved in this application such as the doping concentration of the doping element can be detected therefor.

[0048] In the present application, the silicon substrate has the doping element antimony, which is usually present when the bare silicon wafer is prepared, so the doping concentration of the doping element of the silicon substrate is roughly uniform in all parts of the silicon substrate, that is, the average concentration is roughly the same.

[0049] In a specific embodiment of the present application, the total element concentration per unit volume of antimony element in the silicon substrate of the present application is a atoms / cm 3 , preferably, the range of a is 1E13~1E18.

[0050] Those skilled in the art can understand that the silicon substrate of the present application can further include other doping elements to form doping regions with different functions. Different regions will be formed on the silicon substrate based on different battery structures. For example, a hole collection region and an electron collection region can be formed on one side of the silicon substrate, or a hole collection region and an electron collection region can be formed on both sides of the silicon substrate. Those skilled in the art can form hole collection regions and / or electron collection regions on the silicon substrate according to methods they know. There is no limitation on the number and size of the hole collection regions and electron collection regions. Those skilled in the art can design according to the structure, size and requirements of the actual battery.

[0051] In the present application, the method for detecting whether a certain element is contained in the silicon substrate and the doped region can be detected by SIMS, SSMS, ICP-MS, GDMS, ECV and other methods, preferably by SIMS, SSMS method to detect metal elements. In the present application, solar cells are also referred to as batteries.

[0052] In the present application, the concentration of the doping element (antimony element) in the silicon substrate can be detected by any known method to those skilled in the art, and those skilled in the art can select based on demand, for example, by SIMS, SSMS, ICP-MS, GDMS, ECV and other methods, preferably by SIMS, SSMS method detection. Those skilled in the art can understand that the concentration of the doping element can refer to the concentration of the doping element at any site on the surface of the silicon substrate, in the middle or inside of the silicon substrate, and of course it can also be the average value of the concentration of the doping element of the silicon substrate at multiple locations or the average value of the concentration of the doping element on the entire silicon substrate. Those skilled in the art can select the above-mentioned arbitrary sites for detection based on the actual situation based on the detection conditions and the instruments used, or can calculate the average value of multiple sites after detecting multiple sites as the concentration of the doping element of the silicon substrate. In a specific embodiment, the concentration of the doping element of the silicon substrate refers to the average value detected on the thickness of the silicon substrate, for example, the concentration of the doping element in the silicon substrate is detected in a thickness direction using SIMS or SSMS method, and the average value in this thickness direction is obtained. In the present application, when the concentration of antimony is mentioned, it usually refers to the average concentration of antimony. However, the doping of antimony in the silicon substrate is usually relatively uniform, and the average concentration may also be the concentration at any site.

[0053] In a specific embodiment of the present application, only antimony is doped as a doping element of the fifth main group in the silicon substrate of the present application to replace phosphorus doping. In this case, those skilled in the art can understand that depending on the different sources of the silicon substrate raw materials, the silicon substrate itself may contain other elements, such as any one, two or three of phosphorus, gallium and germanium, but only antimony is actively doped as a doping element of the fifth main group to replace phosphorus doping. Usually, in a silicon substrate, the crystalline silicon lattice is distorted due to the doping of a single element, resulting in many defects in the heavily doped area; but in a specific embodiment of the present application, since the silicon substrate body contains antimony, it can be further doped with the third main group and the fifth main group to form co-doping, which can also overcome the crystalline silicon lattice distortion caused by the doping of a single element and avoid many defects in the heavily doped area.

[0054] like Figure 1 The schematic diagram of a typical back-contact solar cell is shown. A solar cell usually has a silicon substrate 4, a positive electrode, i.e., a first electrode 1, and a negative electrode, i.e., a second electrode 5, wherein the positive electrode forms contact with a P-type semiconductor and the negative electrode forms contact with an N-type semiconductor. When the electrodes are connected to an external circuit under illumination, the entire solar cell can output current. Figure 1 In the figure, the region formed by the P-type semiconductor on the left is the hole collection region, and the region formed by the N-type semiconductor on the right is the electron collection region.

[0055] Furthermore, if Figure 1 An interface passivation layer 9 (also referred to as a tunneling layer) is provided on the surface of the silicon substrate 4, and the thickness of the interface passivation layer 9 is 0.1-5 nm, for example, it can be 0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, etc.; the material of the interface passivation layer 9 can be a material commonly used by technicians in this field, and can be selected from silicon oxide, aluminum oxide, silicon nitride, intrinsic amorphous silicon and other materials according to the specific type of the battery.

[0056] Furthermore, a semiconductor layer 3 is provided on the side of the interface passivation layer 9 away from the silicon substrate 4. The material of the semiconductor layer 3 can be a material commonly used by those skilled in the art, and can be selected from one or more of polycrystalline silicon, amorphous silicon, and microcrystalline silicon according to the specific type of the battery. The semiconductor layer 3 can be a mixture or a stack of multiple materials. Figure 1 In the battery structure shown, the hole collection region and the electron collection region can be isolated by the isolation region 6. Further, a passivation layer 2 can be provided on the semiconductor layer 3.

[0057] The silicon substrate 4 of the present application may have some other doped regions, which may be formed by doping the semiconductor layer 3 into the silicon wafer via the interface passivation layer 9. It may also be formed by direct doping.

[0058] In the present application, in addition to antimony element doped into the silicon substrate 4, other elements may be further doped, such as third main group elements or fifth main group elements, third main group elements such as boron, aluminum, gallium, indium, thallium, and fifth main group elements such as nitrogen, phosphorus, arsenic, antimony, and bismuth.

[0059] In a specific manner, part of the silicon substrate 4 is doped with phosphorus, and part of the silicon substrate 4 is doped with boron. In a specific manner, the interface passivation layer refers to a layer that has a passivation effect and allows the doped elements to pass through, such as a tunneling layer.

[0060] Figure 2 The back electrode pattern of an IBC (Interdigitated back contact) cell is shown, which refers to a two-dimensional structure of the electrode of a cross-back contact cell. A hole collection region and an electron collection region arranged in a cross-shaped manner are formed on the backlight side of the silicon substrate. At the same time, the positive and negative electrodes are also arranged in a cross-shaped manner on the backlight side of the cell. In this application, there is no limitation on the type of cell used in the IBC cell, as long as the first emitter (i.e., the electron collection region) and the second emitter (i.e., the hole collection region) are arranged crosswise on the backlight side.

[0061] In the present application, the front side of the silicon substrate refers to the surface facing the sunlight under normal working conditions of the cell, and the backlight side refers to the surface on the other side of the silicon substrate opposite to the front side.

[0062] like Figure 2 As shown in FIG. 1 , a plurality of collector grid lines are formed on the back side of the silicon substrate. Figure 2 The center spacing of IBC fine grid lines of the same polarity is shown in Figure d. Figure 2 For example, the center distance between the thin gate lines of the first electrode is d1, and the center distance between the thin gate lines of the second electrode is d2, d1=d2=d.

[0063] In the present application, the density of collector grid lines of the same polarity in the direction perpendicular to the collector grid lines is n / cm. A person skilled in the art can determine the average number of collector grid lines per centimeter by visual observation, for example, by counting, or by counting to determine the total number of collector grid lines arranged on the entire silicon substrate, and dividing by the length of the entire silicon substrate (in the direction perpendicular to the collector grid lines) to determine the grid line density. For back-contact cells, since collector grid lines of different polarities are arranged on the same side, it is usually necessary to further divide by 2 to obtain the average number of collector grid lines of the same polarity. In addition, the grid line density can also be obtained by the number of collector grid lines of the same polarity and the battery length in the direction perpendicular to the collector grid lines.

[0064] Figure 3 This is the back electrode pattern of the double-sided contact battery. Figure 3 In the battery structure, the entire surface of one side of the silicon substrate is an electrode of the same polarity, and the electrode of the same polarity includes parallel or approximately parallel collector grid lines, i.e., fine grid lines. The entire surface of the other side of the silicon substrate forms an electrode of the opposite polarity. In addition, the electrode may also include Figure 3 The main grid lines are perpendicular to the fine grid lines shown in FIG. Wherein, the center distance between the fine grid lines of the same polarity is d, as shown in FIG. Figure 3 shown.

[0065] Similar to the above-mentioned back contact electrode, a person skilled in the art can calculate the number by measuring the distance d between adjacent collector grid lines and dividing the total length of the battery in the direction perpendicular to the collector grid lines by the length d. A person skilled in the art can also fully understand that the above-mentioned method for calculating or measuring the number of roots is only listed, and a person skilled in the art can calculate it completely according to the actual situation.

[0066] In the present application, when calculating the gate line density of collector gate lines of the same polarity per unit length in the direction perpendicular to the collector gate lines of the present application, the technical personnel in this field also clearly state that it is only for the area where the collector gate lines are set. If the collector gate lines are uniformly set on the silicon substrate, the entire silicon substrate can be used as the basis for calculating the collector gate lines. If they are only set in a local area of ​​the battery silicon substrate, the local area should be used as the measurement of the total length of the area where the collector gate lines are set, and then the gate line density per unit length is calculated.

[0067] The applicant of the present application has found through in-depth research that in a specific embodiment of the present application, a battery of the present application includes: a silicon substrate, and a plurality of collector grid lines formed on a side surface of the silicon substrate; the silicon substrate is doped with antimony; in a direction perpendicular to the collector grid lines, the grid line density of the collector grid lines of the same polarity per unit length is n / cm. The grid line density n and the concentration of antimony in the substrate of the silicon wafer a atoms / cm 3 Satisfies the following relationship:

[0068] n≥35-klg a Formula 1.

[0069] In the present application, the collector grid line is a grid line used to collect carriers, and is generally referred to as a fine grid line.

[0070] There is no restriction on the form of the battery, and it can be applied to various types of solar cells, including aluminum back side field cells (Al-BSF), passivated emitter and back contact cells (PERC), metal perforated wound cells (MWT); passivated emitter back localized diffused cells (PERL), passivated emitter back fully diffused cells (PERT), emitter perforated wound cells (EWT), tunneling oxide passivated cells (TOPCon), interdigitated back contact cells (IBC), crystalline silicon heterojunction cells (HJT / HIT), and full back electrode back contact heterojunction cells (HBC).

[0071] In a specific embodiment, if it is a double-sided contact battery, the solution of the present application is applicable to the design of both the front and back electrode collector grid lines, and both can be designed according to the solution of the present application. The data in the specific implementation method takes the front grid line as an example.

[0072] In some specific embodiments, it can be a battery having at least a partial TOPCon structure, including a TOPCon battery, a partial TOPCon battery, a back-contact hybrid battery and a TBC battery, or it can be a crystalline silicon heterojunction battery (HJT / HIT) or a full back electrode back-contact heterojunction battery (HBC).

[0073] In a specific embodiment, k is less than or equal to 2, for example, it can be 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0.

[0074] For various types of batteries, by effectively controlling the number of collector grid lines, that is, satisfying Formula 1, the effect of lateral transmission can be effectively improved. Good battery efficiency Eta and open circuit voltage can be obtained, while short circuit current and fill factor are also relatively excellent, that is, the efficiency of the battery cell can be effectively improved.

[0075] In a specific embodiment, the number of collector grid lines n of the same polarity per unit length (i.e., the grid line density n / cm) is further corrected and calculated according to the thickness of the silicon substrate in different solar cells. When the thickness of the silicon substrate is b μm, the grid line density n and the concentration a of the antimony element in the silicon substrate satisfy the following relationship:

[0076]

[0077] Wherein, the constant c is 50μm. Based on Formula 2, the thinner the silicon substrate, the greater the impact of the resistance of lateral carrier transmission on the gate line design, and the more gate lines are needed to improve battery performance. When the thickness b of the silicon substrate is 50-100μm or 100-180μm, different value ranges can be calculated based on Formula 2.

[0078] In a specific implementation, n satisfies the following relationship:

[0079] n≤35-lg a formula 3

[0080] Generally speaking, the more gate lines there are, the larger the contact area between the metal and the silicon semiconductor, and the easier it is for the carriers in the silicon substrate to be recombined. Therefore, the higher the gate line density, the better. There is a certain upper limit. And because there is usually a higher carrier recombination rate at the electrode (the recombination rate is measured by the reverse saturation current density), the larger the recombination rate, the more serious the recombination, and the more serious the battery, so the higher the gate line density, the better. There is a certain upper limit. At the same time, the more gate lines there are, the more serious the battery shading is. Therefore, for n, both formula 1 and formula 3 are satisfied, that is, 35-klg a≤n≤35-lg a, the effect of lateral transmission and the influence of shading on battery efficiency can be effectively balanced, and the battery efficiency is better.

[0081] In a specific embodiment, the grid line density in the above formulas 1, 2 and 3 of the present application can be applicable to the front and back thin grid lines of a double-sided contact battery, including the PN junction side and the high-low junction side; it is also applicable to the back grid lines of a BC battery, including the back positive fine grid lines and the back negative fine grid lines.

[0082] In a specific embodiment, for a double-sided contact battery, when the positive electrode and the negative electrode of the battery are distributed on two different surfaces of the battery, preferably k=2.

[0083] Double-sided contact battery refers to a battery that collects carriers on the same or different surfaces through doped regions on different surfaces. The positive and negative electrodes can be directly on both sides, or the electron holes can be extracted from both sides separately, but in the end the positive and negative electrodes are on the same side of the battery.

[0084] In a specific embodiment of the present application, the double-sided contact cell may be a metal through-hole wound (MWT) cell or an emitter through-hole wound (EWT) cell.

[0085] In a specific embodiment of the present application, the double-sided contact cell is a TOPCon cell. Figure 7 A typical structure of a double-sided contact cell involved in the present application is shown. A semiconductor layer 3 is provided on the side of the interface passivation layer 9 away from the silicon substrate 4. Further, a passivation layer 2 can be provided on the semiconductor layer 3. Furthermore, the solar cell has a silicon substrate 4, a first electrode 1 and a second electrode 5. Figure 7 In the figure, the upper region formed by P-type semiconductor is the hole collection region, and the lower region formed by N-type semiconductor is the electron collection region.

[0086] In a specific embodiment, for a back-contact battery, when the positive electrode and the negative electrode of the battery are arranged on one surface of the battery, k = 1.9. The inventor of the present application has found through a large number of experiments that for a back-contact battery, k is more accurate when it is 1.9.

[0087] In a specific embodiment of the present application, the back contact cell is a back contact hybrid cell.

[0088] In a specific embodiment of the present application, the back contact cell is a TBC cell.

[0089] In a specific embodiment of the present application, the back contact cell is a full back electrode back contact heterojunction cell.

[0090] In a specific embodiment, for the case of a back contact battery, there is usually an electron collection region and a hole collection region on one side of the battery, and an isolation region between the electron collection region and the hole collection region; when the depth of the isolation region between the electron collection region and the hole collection region of the battery is d μm, n satisfies the following relationship:

[0091]

[0092] The depth of the isolation region is the numerical height difference corresponding to the average depth of the bottom of the isolation region from the bottom of the shallower area in the electron collection region and the hole collection region, that is, the vertical depth from the interface between the tunneling layer of the hole collection region or the electron collection region and the substrate (that is, the surface of the silicon substrate) to the deepest part of the isolation region. If the heights of the hole collection region and the electron collection region are different, the higher region is selected to obtain the vertical depth to the deepest part of the isolation region.

[0093] The isolation region refers to an electrically insulating region (or gap region) introduced between the hole collection region and the electron collection region, thereby avoiding direct lateral contact between the hole collection region and the electron collection region. It is not difficult for a person skilled in the art to understand that the height difference d refers to the vertical height difference corresponding to the average depth of the bottom of the isolation region from the bottom of the shallower region of the electron collection region and the hole collection region, or when the solar cell contains an interface passivation layer, the bottom of the electron collection region or the hole collection region is the height of the interface passivation layer close to the silicon substrate.

[0094] In one embodiment, the structure of the back contact battery is as shown in Figure 4 As shown, the hole collection region 7 and the electron collection region 8 are separated by the isolation region 6, wherein the hole collection region 7 is the higher region of the two regions, so the height difference d is as shown in FIG. Figure 4 As shown, it refers to the difference between the bottom of the hole collection region 7 and the bottom of the isolation region 6.

[0095] In a specific embodiment, the hole collection region, the electron collection region and the isolation region of the solar cell involved in the present application are at the same height, that is, the depths are the same, so there is no height difference.

[0096] In a specific embodiment, the present application provides a solar cell structure, wherein the structure is as follows: Figure 5 As shown, the depths of the hole collection region and the electron collection region are the same, and the numerical height difference corresponding to the average depth of the bottom of any one of the hole collection region and the electron collection region and the bottom of the isolation region is d.

[0097] The present application provides a schematic diagram of the structure of a solar cell, such as Figure 6 As shown, the depths of the hole collection region and the electron collection region are the same, and the numerical height difference corresponding to the average depth of the bottom of any one of the hole collection region and the electron collection region and the bottom of the isolation region is d.

[0098] For a back contact cell with a numerical height difference d, if the above formula 4 (k=1.9) is satisfied, such a setting can effectively balance the effects of lateral transmission, longitudinal transmission and the influence of shading on cell efficiency.

[0099] In a specific embodiment, the concentration a of the antimony element ranges from 1E13 to 1E18 atom / cm 3 .

[0100] For example, the concentration a of the antimony element may be 1E13 atom / cm 3 , 1E14 atom / cm 3 , 1E15atom / cm 3 , 1E16 atom / cm 3 , 1E17 atom / cm 3 , 1E18 atom / cm 3 Etc. For example, it can be 2E13 atom / cm 3 、3E13 atom / cm 3 、4E13 atom / cm 3 、5E13 atom / cm 3 、6E13atom / cm 3 、7E13 atom / cm 3 、8E13 atom / cm 3 、9E13atom / cm 3 , 1E14 atom / cm 3 , 4E+14 atom / cm 3 4.1E+14 atom / cm 3、4.2E+14atom / cm 3 、4.3E+14atom / cm 3 、4.4E+14atom / cm 3 、4.5E+14atom / cm 3 、4.6E+14atom / cm 3 、4.7E+14atom / cm 3 、4.8E+14atom / cm 3 、4.9E+14atom / cm 3 、5E+14atom / cm 3 、5.1E+14atom / cm 3 、5.2E+14atom / cm 3 、5.3E+14atom / cm 3 、5.4E+14atom / cm 3 、5.5E+14atom / cm 3 、5.6E+14atom / cm 3 、5.7E+14atom / cm 3 、5.8E+14atom / cm 3 、5.9E+14atom / cm 3 、6E+14atom / cm 3 、6.1E+14atom / cm 3 、6.2E+14atom / cm 3 、6.3E+14atom / cm 3 、6.4E+14atom / cm 3 、6.5E+14atom / cm 3 、6.6E+14atom / cm 3 、6.7E+14atom / cm 3 、6.8E+14atom / cm 3 、6.9E+14atom / cm 3 、7E+14atom / cm 3 、7.1E+14atom / cm 3 、7.2E+14atom / cm 3 、7.3E+14atom / cm 3 、7.4E+14atom / cm 3 、7.5E+14atom / cm 3 、7.6E+14atom / cm 3 、7.7E+14atom / cm 3、7.8E+14atom / cm 3 、7.9E+14atom / cm 3 、8E+14atom / cm 3 、8.1E+14atom / cm 3 、8.2E+14atom / cm 3 、8.3E+14atom / cm 3 、8.4E+14atom / cm 3 、8.5E+14atom / cm 3 、8.6E+14atom / cm 3 、8.7E+14atom / cm 3 、8.8E+14atom / cm 3 、8.9E+14atom / cm 3 、9E+14atom / cm 3 、9.1E+14atom / cm 3 、9.2E+14atom / cm 3 、9.3E+14atom / cm 3 、9.4E+14atom / cm 3 、9.5E+14atom / cm 3 、9.6E+14atom / cm 3 、9.7E+14atom / cm 3 、9.8E+14atom / cm 3 、9.9E+14atom / cm 3 、1E+15atom / cm 3 、1.1E+15atom / cm 3 、1.2E+15atom / cm 3 、1.3E+15atom / cm 3 、1.4E+15atom / cm 3 、1.5E+15atom / cm 3 、1.6E+15atom / cm 3 、1.7E+15atom / cm 3 、1.8E+15atom / cm 3 、1.9E+15atom / cm 3 、2E+15atom / cm 3 、2.1E+15atom / cm 3 、2.2E+15atom / cm 3 、2.3E+15atom / cm 3、2.4E+15atom / cm 3 、2.5E+15atom / cm 3 、2.6E+15atom / cm 3 、2.7E+15atom / cm 3 、2.8E+15atom / cm 3 、2.9E+15atom / cm 3 、3E+15atom / cm 3 、3.1E+15atom / cm 3 、3.2E+15atom / cm 3 、3.3E+15atom / cm 3 、3.4E+15atom / cm 3 、3.5E+15atom / cm 3 、3.6E+15atom / cm 3 、3.7E+15atom / cm 3 、3.8E+15atom / cm 3 、3.9E+15atom / cm 3 、4E+15atom / cm 3 、4.1E+15atom / cm 3 、4.2E+15atom / cm 3 、4.3E+15atom / cm 3 、4.4E+15atom / cm 3 、4.5E+15atom / cm 3 、4.6E+15atom / cm 3 、4.7E+15atom / cm 3 、4.8E+15atom / cm 3 、4.9E+15atom / cm 3 、5E+15atom / cm 3 、5.1E+15atom / cm 3 、5.2E+15atom / cm 3 、5.3E+15atom / cm 3 、5.4E+15atom / cm 3 、5.5E+15atom / cm 3 、5.6E+15atom / cm 3 、5.7E+15atom / cm 3 、5.8E+15atom / cm 3 、5.9E+15atom / cm 3、6E+15atom / cm 3 、6.1E+15atom / cm 3 、6.2E+15atom / cm 3 、6.3E+15atom / cm 3 、6.4E+15atom / cm 3 、6.5E+15atom / cm 3 、6.6E+15atom / cm 3 、6.7E+15atom / cm 3 、6.8E+15atom / cm 3 、6.9E+15atom / cm 3 、7E+15atom / cm 3 、7.1E+15atom / cm 3 、7.2E+15atom / cm 3 、7.3E+15atom / cm 3 、7.4E+15atom / cm 3 、7.5E+15atom / cm 3 、7.6E+15atom / cm 3 、7.7E+15atom / cm 3 、7.8E+15atom / cm 3 、7.9E+15atom / cm 3 、8E+15atom / cm 3 、8.1E+15atom / cm 3 、8.2E+15atom / cm 3 、8.3E+15atom / cm 3 、8.4E+15atom / cm 3 、8.5E+15atom / cm 3 、8.6E+15atom / cm 3 、8.7E+15atom / cm 3 、8.8E+15atom / cm 3 、8.9E+15atom / cm 3 、9E+15atom / cm 3 、9.1E+15atom / cm 3 、9.2E+15atom / cm 3 、9.3E+15atom / cm 3 、9.4E+15atom / cm 3 、9.5E+15atom / cm 3、9.6E+15atom / cm 3 、9.7E+15atom / cm 3 、9.8E+15atom / cm 3 、9.9E+15atom / cm 3 、1E+16atom / cm 3 , 1.1E+16atom / cm 3 、1.2E+16atom / cm 3 、1.3E+16atom / cm 3 , 1.4E+16atom / cm 3 、1.5E+16atom / cm 3 、1.6E+16atom / cm 3 、1.7E+16atom / cm 3 、1.8E+16atom / cm 3 、1.9E+16atom / cm 3 、2E+16atom / cm 3 、3E+16atom / cm 3 、4E+16atom / cm 3 、5E+16atom / cm 3 、6E+16atom / cm 3 、7E+16atom / cm 3 、8E+16atom / cm 3 、9E+16atom / cm 3 、1E+17atom / cm 3 、2E+17atom / cm 3 、3E+17atom / cm 3 、4E+17atom / cm 3 、5E+17atom / cm 3 、6E+17atom / cm 3 、7E+17atom / cm 3 、8E+17atom / cm 3 、9E+17atom / cm 3 and any range between these values.

[0101] The present application dopes Sb element into the silicon substrate. Due to the low concentration of doping, there are few defects, which can improve the charge mobility of the silicon substrate and reduce the resistivity of the silicon substrate. Secondly, the Sb element at this concentration can reduce the differentiation of the crystalline silicon band edge energy levels caused by doping, and the Sb element doping ionization rate is relatively high.

[0102] Examples and Comparative Examples

[0103] 1. Initial formula acquisition

[0104] First, a silicon substrate was prepared using conventional methods in the art, and the concentration of antimony was detected and selected to be 8.00E+16cm by adjusting the doping amount of Sb dopant. -3 、1.00E+16cm -3 、2.40E+15cm -3 、9.00E+14cm -3 4.50E+14cm -3 、3.00E+14cm -3 、2.20E+14cm -3 4.40E+13cm -3 The concentration of antimony element in the silicon substrate is detected by a conventional method in the art.

[0105] The silicon substrate is made into a battery, and different grid line densities are set, and then the battery performance is tested respectively.

[0106] For the silicon substrate with the same antimony concentration, the distribution of cell efficiency with different grid line densities, that is, the trend diagram of cell performance (based on conversion efficiency Eta) with different grid line densities under the same silicon substrate, such as Figures 8 to 11 As shown in Figure 1, it is found that within a certain range, as the grid line density decreases, the electrical performance tends to decrease. And below a certain grid line density, the electrical performance decreases very quickly. This specific grid line density is recorded as the inflection point grid line density; then data fitting is performed based on different antimony concentrations and the corresponding inflection point grid line density n. The results are as follows Fig.12 shown.

[0107] like Fig.12 As shown, the horizontal axis represents the antimony doping concentration a in the silicon substrate, in cm -3 ; The ordinate represents the grid line density n, and the unit is root / cm; it can be seen that the fitting curve formula is y=35-2lgx, that is, n=35-2lga; when n and a satisfy the formula 35-2lg a, that is, n≥35-2lg a, the efficiency of the solar cell increases significantly, if n<35-2lga, the efficiency of the solar cell decreases significantly.

[0108] It can be seen that when the grid line density n of the actual battery is greater than the lower critical value (35-2lg a), the electrical performance level is significantly higher. When the n of the actual battery is greater than the lower critical value, the electrical performance level is relatively low.

[0109] 2. Verification of solar cell performance

[0110] Preparation Example

[0111] First, a silicon substrate was prepared using conventional methods in the art, and the concentration of antimony was detected and selected to be 8.00E+16cm by adjusting the doping amount of Sb dopant. -3 、1.00E+16cm -3 、2.40E+15cm -3 、9.00E+14cm -3 4.50E+14cm -3 、3.00E+14cm -3 、2.20E+14cm -3 4.40E+13cm -3 The concentration of antimony element in the silicon substrate is detected by a conventional method in the art.

[0112] Example 1 for double-sided contact battery

[0113] Preparation of batteries 1-1 to 1-10

[0114] The antimony-doped silicon substrates obtained in the preparation example were used to prepare Figure 7 The double-sided contact cell structure shown in the figure is a TOPCon solar cell, wherein the concentration of antimony element used in Examples 1-1 and 1-6 is 8.00E+16cm -3 The silicon substrate, the concentration of antimony element used in Examples 1-2 and 1-7 is 1.00E+16cm -3 The concentration of antimony element used in Examples 1-3 and 1-8 is 9.00E+14cm -3 The silicon substrate, the antimony concentration of Examples 1-4 and 1-9 is 8.00E+14cm -3 The silicon substrate, and the antimony concentration of Examples 1-5 and 1-10 is 4.00E+14cm -3 The thickness of the silicon substrate of Examples 1-1 to 1-5 is 150 μm; the thickness of the silicon substrate of Examples 1-6 to 1-10 is 100 μm.

[0115] The solar cells prepared in Examples 1-1 to 1-10 were tested using an IV tester, specifically a photovoltaic electrical performance testing device produced by Halm. When preparing the test samples, 100 experimental pieces were prepared in each group, and the final finished cell pieces ranged from 30 to 100 pieces. The median efficiency of each group was taken to obtain Isc, Uoc, FF and Eta performance. The results are shown in Tables 1 and 2, respectively.

[0116] Table 1 Results of double-sided contact cells with a thickness of 150 μm

[0117]

[0118]

[0119] Table 2 Results of double-sided contact cells with a thickness of 100 μm

[0120]

[0121] Based on the results of Example 1, it can be seen that in the case of a double-sided contact battery, that is, the positive and negative electrodes of the battery are distributed on two different sides of the battery, when the relationship between the grid line density n and the antimony doping concentration a does not conform to Formula 1, the performance of Isc, Uoc, FF and Eta of the solar cell is not good; as the grid line density increases, when the relationship between the grid line density n and the antimony doping concentration a satisfies Formula 1, the performance of Isc, Uoc, FF and Eta of the solar cell is better; when the relationship between the grid line density n and the antimony doping concentration a satisfies Formula 2, the performance of Isc, Uoc, FF and Eta of the solar cell is better.

[0122] For the data in Table 1, at different concentrations, according to the order of increasing grid line density in this embodiment, the trend diagrams of the Eta performance data are as follows: Figure 8 For the data in Table 2, at different concentrations, according to the order of increasing grid line density under this embodiment, the trend diagrams of the Eta performance data are as follows: Fig. 9 It should be noted that Figure 8 and Fig. 9 The horizontal axis in only represents the grid line density data serial number in this embodiment and has no actual physical meaning.

[0123] from Figure 8 and Fig. 9 In the figure, the data on the left side of the vertical dotted line do not satisfy Formula 1. It can be seen that when Formula 1 is not satisfied, the battery performance decreases rapidly.

[0124] Example 2 for back contact cells

[0125] Preparation of batteries 2-1 to 2-10

[0126] The antimony-doped silicon substrate obtained in the preparation example was used to prepare a back contact battery structure. The battery structure is as follows: Figure 1 As shown, the gate line structure is as follows Figure 2 As shown. In Examples 2-1 and 2-6, the concentration of antimony element used is 8.00E+16cm -3 The silicon substrate, the concentration of antimony element used in Examples 2-2 and 2-7 is 1.00E+16cm -3 The silicon substrate, the concentration of antimony element used in Examples 2-3 and 2-8 is 9.00E+14cm -3 The silicon substrate, the concentration of antimony element used in Examples 2-4 and 2-9 is 8.00E+14cm-3 The silicon substrate, the concentration of antimony element used in Examples 2-5 and 2-10 is 4.00E+14cm -3 of silicon substrates, and based on the thickness of different silicon substrates, the depth of the isolation area of ​​different back contact batteries.

[0127] For the solar cells prepared in Examples 2-1 to 2-15, the Isc, Uoc, FF and Eta performances were tested using the same method as in Example 1. The results are shown in Tables 3 and 4, respectively.

[0128] Table 3 Results of back contact cells with a thickness of 150 μm

[0129]

[0130]

[0131]

[0132] Table 4 Results of back contact cells with a thickness of 100 μm

[0133]

[0134]

[0135]

[0136] Based on the results in Tables 3 and 4, it can be seen that in the case of a back-contact battery, that is, the positive and negative electrodes of the battery are both on one side of the battery, at this time, when n≥35-1.9lga, the Isc, Uoc, FF and Eta performance of the solar cell are good, and when this formula is not satisfied, the Isc, Uoc, FF and Eta performance are poor.

[0137] In addition, when n conforms to Formula 2, the Isc, Uoc, FF and Eta performance of the solar cell are better. The inventor speculates that the reason is that the carriers not only need to pass through the thickness direction of the silicon substrate, but also usually need to move laterally between the positive and negative electrodes on the back. During the lateral transmission process, the path passed is longer, so more gate lines need to be set per unit length to offset this effect.

[0138] When n conforms to formula 4, the performance of Isc, Uoc, FF and Eta of the solar cell can be further improved.

[0139] For the data in Table 3, at different concentrations, according to the order of increasing grid line density in this embodiment, the trend diagrams of the Eta performance data are as follows: Fig.10 For the data in Table 4, at different concentrations, according to the order of increasing grid line density under this embodiment, the trend diagrams of the Eta performance data are as follows: Fig.11 It should be noted that Fig.10 and Fig.11 The horizontal axis in only represents the grid line density data serial number in this embodiment and has no actual physical meaning.

[0140] exist Fig.10 and Fig.11 In the figure, the data on the left side of the vertical dotted line do not satisfy Formula 1. It is more obvious that when Formula 1 is not satisfied, the battery performance decreases rapidly.

[0141] Although the embodiments of the present application are described above, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are merely illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present application, all of which belong to the protection of the present application.

Claims

1. A solar cell, comprising: A silicon substrate, and a plurality of collector grid lines formed on a surface of one side of the silicon substrate; The silicon substrate is doped with antimony element, The density of collector gate lines of the same polarity in a direction perpendicular to the collector gate lines is n / cm, and the concentration of antimony elements in the silicon substrate is a atoms / cm 3 When , n and a satisfy the following relationship: n≥35-klg a Formula 1, Wherein, k is less than or equal to 2; The range of a is 1E13~2E17, Among them, n and a also satisfy the following relationship: n≤35-lg a Formula 3.

2. The solar cell according to claim 1, wherein: When the thickness of the silicon substrate of the battery is b μm, n satisfies the following relationship: Wherein, c is a constant and its value is 50 μm.

3. The solar cell according to claim 1 or 2, wherein: The solar cell is a double-sided contact cell, and k=2.

4. The solar cell according to claim 1 or 2, wherein: The solar cell is a back contact cell, and k=1.

9.

5. The solar cell according to claim 4, wherein: One side surface of the silicon substrate has an electron collection region and a hole collection region, and an isolation region between the electron collection region and the hole collection region; when the depth of the isolation region is d μm, n satisfies the following relationship:

6. The solar cell according to claim 5, wherein: The depth of the isolation region is the numerical height difference corresponding to the average depth of the bottom of the shallower region between the electron collection region and the hole collection region from the bottom of the isolation region, and the bottom of the isolation region is the surface of the silicon substrate corresponding to the isolation region. When the solar cell comprises an interface passivation layer, the bottom of the electron collection region or the hole collection region is the height of the interface passivation layer close to the silicon substrate.

7. The solar cell according to claim 1 or 2, wherein: The range of a is 1E14 to 1E17.

8. The solar cell according to claim 1 or 2, wherein: The width of each collector grid line is 10-200 μm.

9. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell according to any one of claims 1 to 8.

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