Solar cell and photovoltaic module

Abstract

The present application provides a solar cell, which comprises: a silicon substrate, and several collector grid lines formed on a side surface of the silicon substrate. The silicon substrate is doped with antimony; the grid line density of collector grid lines having the same polarity per unit length in a direction perpendicular to the collector grid lines is n lines / cm; and when the concentration of antimony in the silicon substrate is a atoms / cm3, n and a satisfy the following relationship: n≥35-klg a, where k is less than or equal to 2. The present application further provides a photovoltaic module formed by the solar cells of the present application.

Description

Solar cell and photovoltaic module

[0001] This application claims priority to Chinese Patent Application No. 202410461849.2 filed on April 16, 2024, and the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of photovoltaic technology, in particular to a solar cell and a photovoltaic module comprising the same. BACKGROUND

[0003] At present, in silicon solar cells, the substrate is usually an N-type or P-type doped silicon wafer. P-type and N-type semiconductors are formed at different positions of the silicon wafer, and then electrodes are respectively formed on the P-type and N-type semiconductor regions, thereby forming a cell. When light enters the silicon cell substrate, electron-hole pairs are generated. The free electron-hole pairs are separated by the carriers, so that the electrons gather near the N pole and the holes gather near the P pole. The electrodes are connected to an external circuit, and an electric current can be output. In the prior art, a P-type semiconductor substrate or an N-type semiconductor substrate is usually used as a photovoltaic semiconductor substrate. The P-type semiconductor substrate is usually doped with boron or gallium elements. The N-type semiconductor substrate is usually doped with phosphorus elements.

[0004] The N-type semiconductor substrate has the advantage of long minority carrier diffusion length, and when applied to the power generation of a silicon solar cell, more carriers can be collected than the P-type semiconductor substrate, and the efficiency is correspondingly higher. The N-type semiconductor substrate is usually doped with phosphorus elements. In the photovoltaic field, it has been studied to use a silicon wafer doped with Sb elements as a silicon substrate to prepare a solar cell and a photovoltaic module. However, the solar cell formed by the Sb-doped silicon substrate still needs to be further optimized to improve the cell efficiency. SUMMARY

[0005] In view of the above problems, the present application aims to improve the problems involved in the above prior art. Through in-depth research, the present application confirms the relationship between the Sb concentration and the grid line density, and realizes the improvement of the transmission effect and the cell efficiency of the solar cell by the combination of the Sb concentration and the number of grid lines in the silicon substrate. The present application provides the following solutions:

[0006] In a first aspect, a solar cell is provided, comprising:

[0007] a silicon substrate, and a plurality of current collecting grid lines formed on one side surface of the silicon substrate; each current collecting grid line extends in the same direction;

[0008] the silicon substrate is doped with antimony elements,

[0009] In a direction perpendicular to the extension direction of the collector grid lines, the grid line density of the collector grid lines of the same polarity is n roots / cm, and the concentration of the antimony element in the silicon substrate is a atoms / cm3, n and a satisfy the following relationship: n≥35-klg a,

[0010] wherein k is a constant less than or equal to 2.

[0011] wherein when the thickness of the silicon substrate of the battery is b μm, the n satisfies the following relationship:

[0012] wherein c is a constant and takes a value of 50 μm.

[0013] wherein n and a also satisfy the following relationship: n≤35-lg a.

[0014] wherein the solar cell is a dual-sided contact cell, and k=2.

[0015] wherein the solar cell is a back contact cell, and k=1.9.

[0016] 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, the n satisfies the following relationship:

[0017] wherein the depth of the isolation region is a height difference corresponding to the average depth of the bottom of the isolation region from the bottom of the electron collection region and the hole collection region, the bottom of the isolation region is the surface of the silicon substrate corresponding to the isolation region,

[0018] When the solar cell contains an interface passivation layer, the bottom of the electron collection region or the bottom of the hole collection region is the surface of the interface passivation layer close to the silicon substrate.

[0019] wherein the range of a is 1E13-1E18.

[0020] wherein the width of each of the collector grid lines is 10 μm-200 μm.

[0021] In a second aspect, a photovoltaic module is provided, which comprises any one of the solar cells.

[0022] Inventive Effects

[0023] The application can effectively improve the effect of carrier lateral transmission based on the battery structure, the concentration of Sb element in the battery silicon substrate, and the number of current collecting grid lines, i.e., can satisfy the above formula one, so as to effectively improve the efficiency of the battery piece. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 shows a schematic diagram of a back contact solar cell.

[0025] Figure 2 shows a back electrode pattern of a back contact cell.

[0026] Figure 3 shows a back electrode pattern of a double-sided contact cell.

[0027] Figure 4 shows a schematic diagram of a back contact solar cell according to an embodiment of the application.

[0028] Figure 5 shows a schematic diagram of a back contact solar cell according to an embodiment of the application.

[0029] Figure 6 shows a schematic diagram of a back contact solar cell according to an embodiment of the application.

[0030] Figure 7 shows a schematic diagram of a double-sided contact solar cell according to an embodiment of the application.

[0031] Figure 8 shows a battery efficiency trend graph of Table 1.

[0032] Figure 9 shows a battery efficiency trend graph of Table 2.

[0033] Figure 10 shows a battery efficiency trend graph of Table 3.

[0034] Figure 11 shows a battery efficiency trend graph of Table 4.

[0035] Figure 12 shows a fitting curve diagram of the antimony doping concentration and the inflection point grid line density.

[0036] Symbol explanation: 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

[0037] The following embodiments of the application are only used to illustrate the specific embodiments of the application, and these embodiments cannot be understood as a limitation of the application. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application are equivalent replacement methods, which fall within the protection scope of the application.

[0038] Specific embodiments of the application will be described in greater detail herein. It should be understood that the application can be embodied in various forms without being limited to the embodiments exemplified herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0039] It should be noted that in the specification and claims, terms such as "comprise", "include", "contain" or "encompass" are used in their open-ended sense to mean that the term "comprising" or "including" or "containing" or "encompassing" is used in its broadest sense to encompass the components listed, and any other components, as well as any sub-ranges or combinations thereof. The specification and claims should not be read to imply that any component, feature, or step is essential or necessary unless explicitly stated as such. The specification and claims should not be read to imply that any component, feature, or step is essential or necessary unless explicitly stated as such.

[0040] As used in this specification and claims, "a" or "an" can mean one or more. As used in this specification and claims, the term "or" as used in the "and / or" can mean "and / or", unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure

[0041] The term "or" is used in the claims to mean "and / or" unless explicitly indicated otherwise. As used herein, "another" can mean at least a second or more.

[0042] In the present application, the silicon substrate itself involved in the following contents of the present application is not further defined, and can be a silicon substrate obtained after machining and slicing after the end of the silicon rod drawing (also referred to as a bare silicon wafer). In the present application, it is also possible to recover and peel off a structure containing a silicon substrate and at least including a partially doped region from a battery assembly, as long as it can have a certain shape and can be in a sheet shape, i.e., a flat or plate shape, in which the size of one face is greater than that of a face perpendicular thereto. The size of the structure containing the silicon substrate body and at least including a partially doped region is also not limited, and the silicon substrate or the structure containing the silicon substrate and at least including a partially doped region can be of any size, and the peeled-off part of the silicon substrate body or the structure containing the silicon substrate body and at least including a partially doped region recovered and peeled off from the battery assembly. In addition, those skilled in the art can understand that, at the time of peeling, if the structure at least including a partially doped region is damaged, but as long as a part of the doped region still exists, it should also be understood as a 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 containing the silicon substrate body and at least including a partially 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±2) mm, (210±2) mm, (215±2) mm, (220±2) mm, (225±2) mm, (230±2) mm, (235±2) mm, (240±2) mm, (245±2) mm, (250±2) mm, (255±2) mm, (260±2) mm, (265±2) mm, (270±2) mm, (275±2) mm, and any range between these values. For example, in a specific embodiment, the thickness of the silicon substrate or the structure containing the silicon substrate and at least including a partially doped region of the present application is at least 70-170 μm, for example, it can be 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm. In a specific embodiment, the size of the peeled-off part of the structure containing the silicon substrate body and at least including a partially doped region recovered and peeled off from the other layer structure can be smaller than the above-mentioned size, as long as the doping concentration of the doping element can be detected therefrom and is equal to the parameters involved in the present application.

[0043] In the present application, the silicon substrate has a doping element of antimony, which is generally present at the time of preparing a bare silicon wafer, so the doping concentration of the doping element of the silicon substrate is substantially uniform in each part of the entire silicon substrate, i.e., the average concentration is substantially the same.

[0044] In one embodiment of the present application, the total elemental concentration of the element antimony in the silicon substrate is a atoms / cm3 3 Preferably, a is in the range of 1E13 to 1E18.

[0045] It is understood by the skilled in the art that the silicon substrate of the present application can further comprise other doping elements to form different functional doping regions. Depending on the structure of the solar cell, different regions can be formed on the silicon substrate, for example, a hole collecting region and an electron collecting region can be formed on one side of the silicon substrate, or a hole collecting region and an electron collecting region can be formed on both sides of the silicon substrate. The skilled in the art can form a hole collecting region and / or an electron collecting region on the silicon substrate according to the methods known to them, and there is no limitation on the number of hole collecting regions and electron collecting regions and the size of the regions, and the skilled in the art can design according to the structure, size and requirements of the actual solar cell.

[0046] In the present application, the detection method of whether an element is contained in the silicon substrate and the doping region can be detected by SIMS, SSMS, ICP-MS, GDMS, ECV and the like, and preferably the metal element is detected by SIMS and SSMS. In the present application, the solar cell is also referred to as a cell.

[0047] In the present application, the concentration of the doping element (antimony element) in the silicon substrate can be detected by any known method of the skilled in the art, which can be selected by the skilled in the art based on the requirements, for example, it can be detected by SIMS, SSMS, ICP-MS, GDMS, ECV and the like, and preferably it is detected by SIMS and SSMS. It is understood by the skilled in the art that the concentration of the doping element can refer to the concentration of the doping element at any site on the surface, middle or interior of the silicon substrate, and of course it can also be the average of the doping element concentration at multiple positions or the average of the doping element concentration on the entire silicon substrate. The skilled in the art can select any of the above-mentioned sites for detection based on the detection conditions and the instruments used, or can calculate the average of the doping element concentration at multiple sites after detecting multiple sites, and use it as the concentration of the doping element in the silicon substrate. In one embodiment, the concentration of the doping element in the silicon substrate refers to the average value detected in the thickness direction of the silicon substrate, for example, the concentration of the doping element in the silicon substrate is detected in the thickness direction by SIMS or SSMS, and the average value of the doping element concentration in the thickness direction is calculated. In the present application, when the concentration of the antimony element is mentioned, it usually refers to the average concentration of the antimony element, but usually the doping of the antimony element in the silicon substrate is uniform, and the average concentration can also be the concentration at any site.

[0048] In one specific embodiment of the present application, only antimony element is doped as the fifth main group doping element in the silicon substrate of the present application to replace phosphorus element doping. In this case, those skilled in the art can understand that depending on the different sources of the silicon substrate raw material, the silicon substrate itself can contain any one or two or three of other elements such as phosphorus, gallium, germanium, but only antimony element is actively doped as the fifth main group doping element to replace phosphorus element doping. Generally, in the silicon substrate, due to single element doping, the crystal silicon lattice is distorted, causing many defects in the heavily doped region; but in one specific embodiment of the present application, since the silicon substrate body has antimony element, it can be further doped with the third main group and the fifth main group to form co-doping, which can overcome the crystal silicon lattice distortion caused by single element doping, and avoid many defects in the heavily doped region.

[0049] As shown in Figure 1, a schematic diagram of a typical back contact solar cell is shown. Generally, the solar cell has a silicon substrate 4, with a positive electrode, i.e. a first electrode 1, and a negative electrode, i.e. a second electrode 5, wherein the positive electrode and the P-type semiconductor form a contact, and the negative electrode and the N-type semiconductor form a contact. In the case of light, the electrodes are connected to an external circuit, and the entire solar cell can output current. In Figure 1, the left side region formed by the P-type semiconductor is a hole collection region, and the right side region formed by the N-type semiconductor is an electron collection region.

[0050] Further, as shown in 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 nm-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 the material commonly used by those skilled in the art, and according to the different types of the battery, it can be selected from silicon oxide, aluminum oxide, silicon nitride, intrinsic amorphous silicon, etc.

[0051] Further, 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 the material commonly used by those skilled in the art, and according to the different types of the battery, it can be selected from one or more of polycrystalline silicon, amorphous silicon, microcrystalline silicon. The semiconductor layer 3 can be a mixture or a laminate of multiple materials. In the battery structure shown in Figure 1, 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.

[0052] The silicon substrate 4 of the present application can have other doping regions, and the doping regions can be formed by doping through the semiconductor layer 3 via the interface passivation layer 9 into the silicon wafer. It can also be formed by direct doping.

[0053] In the present application, the silicon substrate 4 can be further doped with other elements, such as a third main group element or a fifth main group element, in addition to the antimony element, the third main group element, such as boron, aluminum, gallium, indium, thallium, the fifth main group element, such as nitrogen, phosphorus, arsenic, antimony, bismuth.

[0054] In a specific manner, the silicon substrate 4 is doped with phosphorus elements in a partial region and doped with boron elements in a partial region. In a specific embodiment, the interface passivation layer 9 refers to a layer having a passivation effect and allowing the doping elements to pass through, such as a tunneling layer.

[0055] Figure 2 shows the back electrode pattern of an IBC (Interdigitated back contact) cell, which refers to a two-dimensional structure diagram of the electrode of an interdigitated back contact cell, and a back junction back contact solar cell in which the hole collection region and the electron collection region are formed in an interdigital cross arrangement on the back surface of the silicon substrate. In the present application, the type of the cell used in the IBC cell is not limited, as long as the first emitter (i.e., the electron collection region) and the second emitter (i.e., the hole collection region) are arranged in an interdigital cross arrangement on the back surface.

[0056] In the present application, the front surface of the silicon substrate refers to the surface facing the sunlight under normal working conditions of the cell, and the back surface refers to the surface of the other side of the silicon substrate opposite to the front surface.

[0057] As shown in Figure 2, a plurality of collector grid lines are formed on the back surface of the silicon substrate, and each collector grid line extends in the same direction (left-right direction in Figure 2). As shown in Figure 2, the center-to-center distance of the IBC fine grid lines of the same polarity in the direction perpendicular to the extension direction of the collector grid lines (up-down direction in Figure 2) is denoted as pitch hereinafter. Taking Figure 2 as an example, the center-to-center distance of the fine grid lines of the first electrode is pitch1, and the center-to-center distance of the fine grid lines of the second electrode is pitch2, pitch1 = pitch2 = pitch.

[0058] In the present application, in the direction perpendicular to the collector grid lines (i.e. the direction perpendicular to the extension direction of the collector grid lines), the grid line density of the collector grid lines of the same polarity is n roots / cm, the average number of the collector grid lines per centimeter can be determined by visual observation, for example, by counting method, or the total number of the collector grid lines provided on the entire silicon substrate can be counted and divided by the length of the entire silicon substrate (in the direction perpendicular to the collector grid lines) to determine the grid line density. For the back contact cell, since the collector grid lines of different polarities are provided on the same side, it is usually further divided by 2 to obtain the average number of the collector grid lines of the same polarity, in addition, the grid line density can also be obtained by the number of the collector grid lines of the same polarity and the length of the cell in the direction perpendicular to the collector grid lines.

[0059] Figure 3 is a back electrode pattern of a double-sided contact cell. In the cell structure of Figure 3, 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 can also include a main grid line perpendicular to the fine grid line as shown in Figure 3. Among them, the center-to-center distance of the fine grid lines of the same polarity is pitch, as shown in Figure 3.

[0060] Similar to the above-mentioned back contact electrode, the skilled person in the art can calculate the distance pitch between adjacent collector grid lines, and by the total length of the cell in the direction perpendicular to the collector grid lines, the total length is divided by the distance pitch, the skilled person in the art can also fully understand that the above-mentioned calculation method or measurement method of the number of roots is only listed, and the skilled person in the art can fully calculate according to the actual situation.

[0061] In the present application, when calculating the grid line density of the collector grid lines of the same polarity per unit length in the direction perpendicular to the collector grid lines, the skilled person in the art also explicitly means only for the area provided with the collector grid lines, if the collector grid lines are uniformly provided on the silicon substrate, the entire silicon substrate can be taken as the basis for calculating the collector grid lines, if only provided in the local area of the cell silicon substrate, the local area should be taken as the total length of the area provided with the collector grid lines, and then the grid line density per unit length is calculated.

[0062] The width of each collector grid line is 10-200 μm.

[0063] The inventors of the present application have found, through in-depth research, that in specific embodiments of the present application, a battery according to the present application comprises: a silicon substrate, and a plurality of current collecting grid lines formed on one side surface of the silicon substrate; the silicon substrate is doped with antimony elements; in a direction perpendicular to the extension direction of the current collecting grid lines, the grid line density of the current collecting grid lines of the same polarity per unit length is n roots / cm. The grid line density n and the concentration a atoms / cm of the antimony elements in the silicon substrate satisfy the following relationship: n≥35-klga Formula One. 3 The grid line density n and the concentration a atoms / cm of the antimony elements in the silicon substrate satisfy the following relationship: n≥35-klga Formula One.

[0064] In the present application, the current collecting grid line is a grid line for collecting carriers, which can also be referred to as a fine grid line.

[0065] The present application has no restrictions on the form of the battery and can be applied to various types of solar cells, including aluminum back surface field (Al-BSF), passivated emitter and back contact (PERC), metal wrap through (MWT), passivated emitter back locally diffused (PERL), passivated emitter back full diffusion (PERT), emitter wrap through (EWT), tunnel oxide passivated contact (TOPCon), interdigitated back contact (IBC), crystalline silicon heterojunction (HJT / HIT), and full back electrode back contact heterojunction (HBC).

[0066] In a specific embodiment, if it is a bifacial contact battery, the design of the front and back electrode current collecting grid lines according to the present application is applicable, and the front grid line is used as an example in the specific embodiment.

[0067] In some specific embodiments, the battery can be at least partially of the structure of TOPCon, including TOPCon battery, local TOPCon battery, back contact hybrid battery, and TBC battery, and can also be a crystalline silicon heterojunction (HJT / HIT) battery and a full back electrode back contact heterojunction (HBC) battery.

[0068] In a specific embodiment, k is a constant less than or equal to 2, for example, it can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0.

[0069] For various types of batteries, by effectively controlling the number of current collecting grid lines, i.e., satisfying Formula One, the effect of carrier lateral transport can be effectively improved. Good battery efficiency Eta and open circuit voltage can be obtained, and the short circuit current and the fill factor are also excellent, i.e., the efficiency of the battery piece can be effectively improved.

[0070] In one specific embodiment, the number of collecting grid lines of the same polarity per unit length n (i.e. the grid line density n per cm) is further corrected 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:

[0071] wherein the constant c is 50 μm. Based on Equation Two, the thinner the silicon substrate, the greater the impact of the resistance of the carrier lateral transfer on the grid line design, and the more grid lines are needed to improve the performance of the cell. When the thickness of the silicon substrate b is 50 μm-100 μm or 100 μm-180 μm, different numerical ranges can be calculated based on Equation Two.

[0072] In one specific embodiment, n satisfies the following relationship: n≤35-lg a Equation Three

[0073] Generally speaking, the more the number of grid lines, the greater the contact area between the metal and the silicon semiconductor, and the more likely the carriers in the silicon substrate are to be recombined. Therefore, the grid line density is not the greater the better, and there is an upper limit. Since there is usually a higher carrier recombination rate at the electrode (the recombination rate is measured by the reverse saturation current density), the greater the recombination rate, the more serious the recombination, and the lower the efficiency of the cell, so the grid line density is not the greater the better, and there is an upper limit. At the same time, the more the number of grid lines, the more serious the shading of the cell, and therefore, for n satisfying Equation One and Equation Three at the same time, i.e. 35-lg a≤n≤35-lg a, the effect of carrier lateral transfer and the impact of shading on the efficiency of the cell can be effectively balanced, and the efficiency of the cell is more optimal.

[0074] In one specific embodiment, the grid line density in the above-mentioned Equation One, Equation Two and Equation Three of the present application can be applied to the front and back fine grid lines of the double-sided contact cell, including the PN junction side and the high-low junction side; and can also be applied to the back grid lines of the BC cell, including the back positive fine grid lines and the back negative fine grid lines.

[0075] In one specific embodiment, for the double-sided contact cell, when the positive and negative electrodes of the cell are distributed on two different surfaces of the cell, it is preferred that k=2.

[0076] The double-sided contact cell refers to a cell in which carriers are collected to the same or different surfaces through different surface doped regions. The positive and negative electrodes can be directly on both sides, or the electrons and holes can be separately led out from both sides, but finally the positive and negative electrodes are on the same side surface of the cell.

[0077] In one specific embodiment of the present application, the double-sided contact cell can be a metal through hole winding (MWT) cell or an emitter through hole winding (EWT) cell.

[0078] In one specific embodiment of the present application, the bifacial contact cell is a TOPCon cell. FIG. 7 shows a typical structure of the bifacial contact cell involved in the present application. 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 further provided on the semiconductor layer 3. Further, the solar cell has a silicon substrate 4, a first electrode 1 and a second electrode 5. In FIG. 7, the upper part is a hole collection region formed by a P-type semiconductor, and the lower part is an electron collection region formed by an N-type semiconductor.

[0079] In one specific embodiment, for the back contact cell, when the positive and negative electrodes of the cell are provided on one surface of the cell, k = 1.9. The present inventors have found through a large number of experiments that k = 1.9 is more accurate for the back contact cell.

[0080] In one specific embodiment of the present application, the back contact cell is a back contact hybrid cell.

[0081] In one specific embodiment of the present application, the back contact cell is a TBC cell.

[0082] In one specific embodiment of the present application, the back contact cell is a full back electrode back contact heterojunction cell.

[0083] In one specific embodiment, for the case of a back contact cell, there is generally an electron collection region and a hole collection region on one side of the cell, and a separation region between the electron collection region and the hole collection region; when the depth of the separation region between the electron collection region and the hole collection region of the cell is d pm, the n satisfies the following relationship:

[0084] wherein the depth of the separation region is the height difference corresponding to the average depth of the bottom of the shallower region of the electron collection region and the hole collection region from the bottom of the separation region, that is, the vertical depth from the interface (i.e. the silicon substrate surface) of the tunneling layer of the hole collection region or the electron collection region and the substrate to the deepest part of the separation region, and if the heights of the hole collection region and the electron collection region are different, the vertical depth from the interface of the higher region to the deepest part of the separation region is selected.

[0085] 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 contact between the hole collection region and the electron collection region in the lateral direction. It is understood by those skilled in the art 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 bottom of the hole collection region is the surface of the interface passivation layer close to the silicon substrate.

[0086] In one embodiment, the structure of the back contact cell is shown in Figure 4, in which the hole collection region 7 and the electron collection region 8 are separated by the isolation region 6, and the hole collection region 7 is the higher of the two regions, so the height difference d as shown in Figure 4 refers to the difference between the bottom of the electron collection region 8 and the bottom of the isolation region 6.

[0087] In one embodiment, the hole collection region, the electron collection region and the isolation region of the solar cell according to the present application are at the same height, i.e. have the same depth, so there is no height difference.

[0088] In one embodiment, the present application provides a structure of a solar cell, as shown in Figure 5, the depths of the hole collection region and the electron collection region are the same, and the height difference corresponding to the average depth of the bottom of the isolation region from the bottom of either of the hole collection region and the electron collection region is d.

[0089] The present application provides a structure diagram of a solar cell, as shown in Figure 6, the depths of the hole collection region and the electron collection region are the same, and the height difference corresponding to the average depth of the bottom of the isolation region from the bottom of either of the hole collection region and the electron collection region is d.

[0090] For a back contact cell with a height difference d, if the above formula four (k = 1.9) is satisfied, the effect of balancing the lateral and vertical transport of carriers and the effect of shading on the efficiency of the cell can be effectively balanced by such a setting.

[0091] In one embodiment, the concentration a of the antimony element is in the range of 1E13 to 1E18 atom / cm 3 .

[0092] For example, the concentration a of the antimony element can be 1E13 atom / cm 3 , 1E14 atom / cm 3 , 1E15 atom / cm 3 , 1E16 atom / cm 31E17 atom / cm 3 1E18 atom / cm 3 2E13 atom / cm 3 3E13 atom / cm 3 4E13 atom / cm 3 5E13 atom / cm 3 6E13 atom / cm 3 7E13 atom / cm 3 8E13 atom / cm 3 9E13 atom / cm 3 1E14 atom / cm 3 4E+14 atom / cm 3 4.1E+14 atom / cm 3 4.2E+14 atom / cm 3 4.3E+14 atom / cm 3 4.4E+14 atom / cm 3 4.5E+14 atom / cm 3 4.6E+14 atom / cm 3 4.7E+14 atom / cm 3 4.8E+14 atom / cm 3 4.9E+14 atom / cm 3 5E+14 atom / cm 3 5.1E+14 atom / cm 3 5.2E+14 atom / cm 3 5.3E+14 atom / cm 3 5.4E+14 atom / cm 3 5.5E+14 atom / cm 3 5.6E+14 atom / cm 3 5.7E+14 atom / cm 3 5.8E+14 atom / cm 3 5.9E+14 atom / cm 3 6E+14 atom / cm 3 6.1E+14 atom / cm 3 6.2E+14 atom / cm 3 6.3E+14 atom / cm 3 6.4E+14 atom / cm 3 6.5E+14 atom / cm3 , 6.6E+14 atom / cm 3 , 6.7E+14 atom / cm 3 , 6.8E+14 atom / cm 3 , 6.9E+14 atom / cm 3 , 7E+14 atom / cm 3 , 7.1E+14 atom / cm 3 , 7.2E+14 atom / cm 3 , 7.3E+14 atom / cm 3 , 7.4E+14 atom / cm 3 , 7.5E+14 atom / cm 3 , 7.6E+14 atom / cm 3 , 7.7E+14 atom / cm 3 , 7.8E+14 atom / cm 3 , 7.9E+14 atom / cm 3 , 8E+14 atom / cm 3 , 8.1E+14 atom / cm 3 , 8.2E+14 atom / cm 3 , 8.3E+14 atom / cm 3 , 8.4E+14 atom / cm 3 , 8.5E+14 atom / cm 3 , 8.6E+14 atom / cm 3 , 8.7E+14 atom / cm 3 , 8.8E+14 atom / cm 3 , 8.9E+14 atom / cm 3 , 9E+14 atom / cm 3 , 9.1E+14 atom / cm 3 , 9.2E+14 atom / cm 3 , 9.3E+14 atom / cm 3 , 9.4E+14 atom / cm 3 , 9.5E+14 atom / cm 3 , 9.6E+14 atom / cm 3 , 9.7E+14 atom / cm 3 , 9.8E+14 atom / cm 3 , 9.9E+14 atom / cm 3 , 1E+15 atom / cm 3 , 1.1E+15 atom / cm3 1.2E+15 atoms / cm 3 1.3E+15 atoms / cm 3 1.4E+15 atoms / cm 3 1.5E+15 atoms / cm 3 1.6E+15 atoms / cm 3 1.7E+15 atoms / cm 3 1.8E+15 atoms / cm 3 1.9E+15 atoms / cm 3 2E+15 atoms / cm 3 2.1E+15 atoms / cm 3 2.2E+15 atoms / cm 3 2.3E+15 atoms / cm 3 2.4E+15 atoms / cm 3 2.5E+15 atoms / cm 3 2.6E+15 atoms / cm 3 2.7E+15 atoms / cm 3 2.8E+15 atoms / cm 3 2.9E+15 atoms / cm 3 3E+15 atoms / cm 3 3.1E+15 atoms / cm 3 3.2E+15 atoms / cm 3 3.3E+15 atoms / cm 3 3.4E+15 atoms / cm 3 3.5E+15 atoms / cm 3 3.6E+15 atoms / cm 3 3.7E+15 atoms / cm 3 3.8E+15 atoms / cm 3 3.9E+15 atoms / cm 3 4E+15 atoms / cm 3 4.1E+15 atoms / cm 3 4.2E+15 atoms / cm 3 4.3E+15 atoms / cm 3 4.4E+15 atoms / cm 3 4.5E+15 atoms / cm 3 4.6E+15 atoms / cm 3 4.7E+15 atoms / cm3 , 4.8E+15 atoms / cm 3 , 4.9E+15 atoms / cm 3 , 5E+15 atoms / cm 3 , 5.1E+15 atoms / cm 3 , 5.2E+15 atoms / cm 3 , 5.3E+15 atoms / cm 3 , 5.4E+15 atoms / cm 3 , 5.5E+15 atoms / cm 3 , 5.6E+15 atoms / cm 3 , 5.7E+15 atoms / cm 3 , 5.8E+15 atoms / cm 3 , 5.9E+15 atoms / cm 3 , 6E+15 atoms / cm 3 , 6.1E+15 atoms / cm 3 , 6.2E+15 atoms / cm 3 , 6.3E+15 atoms / cm 3 , 6.4E+15 atoms / cm 3 , 6.5E+15 atoms / cm 3 , 6.6E+15 atoms / cm 3 , 6.7E+15 atoms / cm 3 , 6.8E+15 atoms / cm 3 , 6.9E+15 atoms / cm 3 , 7E+15 atoms / cm 3 , 7.1E+15 atoms / cm 3 , 7.2E+15 atoms / cm 3 , 7.3E+15 atoms / cm 3 , 7.4E+15 atoms / cm 3 , 7.5E+15 atoms / cm 3 , 7.6E+15 atoms / cm 3 , 7.7E+15 atoms / cm 3 , 7.8E+15 atoms / cm 3 , 7.9E+15 atoms / cm 3 , 8E+15 atoms / cm 3 , 8.1E+15 atoms / cm 3 , 8.2E+15 atoms / cm 3 , 8.3E+15 atoms / cm3 8.4E+15 atoms / cm 3 8.5E+15 atoms / cm 3 8.6E+15 atoms / cm 3 8.7E+15 atoms / cm 3 8.8E+15 atoms / cm 3 8.9E+15 atoms / cm 3 9E+15 atoms / cm 3 9.1E+15 atoms / cm 3 9.2E+15 atoms / cm 3 9.3E+15 atoms / cm 3 9.4E+15 atoms / cm 3 9.5E+15 atoms / cm 3 9.6E+15 atoms / cm 3 9.7E+15 atoms / cm 3 9.8E+15 atoms / cm 3 9.9E+15 atoms / cm 3 1E+16 atoms / cm 3 1.1E+16 atoms / cm 3 1.2E+16 atoms / cm 3 1.3E+16 atoms / cm 3 1.4E+16 atoms / cm 3 1.5E+16 atoms / cm 3 1.6E+16 atoms / cm 3 1.7E+16 atoms / cm 3 1.8E+16 atoms / cm 3 1.9E+16 atoms / cm 3 2E+16 atoms / cm 3 3E+16 atoms / cm 3 4E+16 atoms / cm 3 5E+16 atoms / cm 3 6E+16 atoms / cm 3 7E+16 atoms / cm 3 8E+16 atoms / cm 3 9E+16 atoms / cm 3 1E+17 atoms / cm 3 2E+17 atoms / cm 33E+17 atom / cm 3 4E+17 atom / cm 3 5E+17 atom / cm 3 6E+17 atom / cm 3 7E+17 atom / cm 3 8E+17 atom / cm 3 9E+17 atom / cm 3 and any range between these values.

[0093] The present application dopes the silicon substrate with Sb element. Due to low concentration doping, defects are few, 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 band edge level of the crystalline silicon caused by doping, and the Sb element doping ionization rate is high.

[0094] Examples and Comparative Examples

[0095] I. Initial formula obtaining

[0096] First, the silicon substrate is prepared using the conventional method in the art, and by adjusting the doping amount of the Sb dopant, the concentration of the antimony element is detected and selected to be 8.00E+16 cm -3 1.00E+16 cm -3 2.40E+15 cm -3 9.00E+14 cm -3 4.50E+14 cm -3 3.00E+14 cm -3 2.20E+14 cm -3 4.40E+13 cm -3 The concentration of the antimony element of the above-mentioned silicon substrate is detected by the conventional method in the art.

[0097] The above-mentioned silicon substrate is made into a battery, and different grid line densities are set, and then the battery performance is tested respectively.

[0098] Figures 8-11 show the trends of the performance (in terms of conversion efficiency Eta) of the solar cells with different grid line densities on the same silicon substrate with the same Sb concentration. Figure 8 shows the efficiency distribution of the solar cells with different grid line densities on the same silicon substrate with the same Sb concentration, where the thickness of the solar cell is 150 μm. Figure 9 shows the efficiency distribution of the solar cells with different grid line densities on the same silicon substrate with the same Sb concentration, where the thickness of the solar cell is 100 μm. It can be seen that within a certain range, the electrical performance decreases with the decrease of the grid line density. And below a certain grid line density, the electrical performance decreases very quickly. The certain grid line density is referred to as the inflection point grid line density. Then, based on the data fitting of the different Sb concentrations and the corresponding inflection point grid line densities n, the result is shown in Figure 12.

[0099] As shown in Figure 12, the abscissa represents the Sb doping concentration a in the silicon substrate, in units of cm -3 ; the ordinate represents the grid line density n, in units of root / cm; it can be seen that the fitting curve formula is y = 35 - 2lgx, i.e. n = 35 - 2lg a; when n and a satisfy the formula 35 - 2lg a, i.e. n ≥ 35 - 2lg a, the efficiency of the solar cell increases very obviously, and if n < 35 - 2lg a, the efficiency of the solar cell decreases very obviously.

[0100] It can be seen that when the grid line density n of the actual solar cell is greater than the lower limit critical value (35 - 2lg a), the electrical performance level is obviously higher. When the n of the actual solar cell is greater than the lower limit critical value, the electrical performance level is selected to be lower.

[0101] II. Verification of the performance of the solar cell

[0102] Preparation Example

[0103] First, the silicon substrate is prepared using the conventional method in the art, and by adjusting the doping amount of the Sb dopant, the silicon substrates with the Sb element concentration of 8.00E+16 cm -3 , 1.00E+16 cm -3 , 2.40E+15 cm -3 , 9.00E+14 cm -3 , 4.50E+14 cm -3 , 3.00E+14 cm -3 , 2.20E+14 cm -3 , and 4.40E+13 cm -3 are detected and selected. The Sb element concentration of the above-mentioned silicon substrate is detected by the conventional method in the art.

[0104] Example 1 is for a double-sided contact solar cell

[0105] Preparation of the battery 1-1~1-10

[0106] The silicon substrate doped with antimony element obtained from the preparation example was used to prepare a double-sided contact battery structure as shown in FIG. 7, which is a TOPCon solar cell. In the examples 1-1 and 1-6, the silicon substrate with a concentration of 8.00E+16 cm-2of antimony element was used, in the examples 1-2 and 1-7, the silicon substrate with a concentration of 1.00E+16 cm-2of antimony element was used, in the examples 1-3 and 1-8, the silicon substrate with a concentration of 9.00E+14 cm-2of antimony element was used, in the examples 1-4 and 1-9, the silicon substrate with a concentration of 8.00E+14 cm-2of antimony element was used, and in the examples 1-5 and 1-10, the silicon substrate with a concentration of 4.00E+14 cm-2of antimony element was used. The thickness of the silicon substrate in the examples 1-1 to 1-5 was 150 μm, and the thickness of the silicon substrate in the examples 1-6 to 1-10 was 100 μm. -3 -3 -3 -3 -3

[0107] For the solar cells prepared in the examples 1-1~1-10, an IV tester, specifically a photovoltaic electrical performance test device produced by the halm company, was used for testing. When preparing the test samples, 100 experimental pieces were prepared for each group, and finally the finished battery pieces were not equal to 30-100 pieces. The efficiency of each group was taken as the median to obtain the Isc, Uoc, FF and Eta performance, and the results are shown in Tables 1 and 2, respectively.

[0108] Table 1: Results of double-sided contact battery with a thickness of 150 μm

[0109] Table 2: Results of double-sided contact battery with a thickness of 100 μm

[0110] Based on the results of the examples 1, it can be seen that in the case of a double-sided contact battery, i.e., 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 meet formula one, the performance of the solar cell Isc, Uoc, FF and Eta is not good; as the grid line density increases, when the relationship between the grid line density n and the antimony doping concentration a meets formula one, the performance of the solar cell Isc, Uoc, FF and Eta is better; when the relationship between the grid line density n and the antimony doping concentration a meets formula two, the performance of the solar cell Isc, Uoc, FF and Eta is better.

[0111] ​​​​​For the data in Table 1, at different concentrations, according to the order of increasing grid line density in this embodiment, the trend graph of Eta performance data is shown in Figure 8; for the data in Table 2, at different concentrations, according to the order of increasing grid line density in this embodiment, the trend graph of Eta performance data is shown in Figure 9; it should be noted that the abscissa in Figures 8 and 9 only represents the data sequence of the grid line density in this embodiment, and has no actual physical meaning.

[0112] In Figures 8 and 9, the data on the left side of the vertical dotted line do not satisfy Formula One, and it can be seen that in the case of not satisfying Formula One, the battery performance decreases rapidly.

[0113] Example 2 for back contact battery

[0114] Preparation of batteries 2-1 to 2-10

[0115] The back contact battery structure was prepared using the silicon substrate doped with antimony element obtained by the preparation example, and the battery structure is shown in Figure 1, and the grid line structure is shown in Figure 2. Among them, examples 2-1 and 2-6 use silicon substrate with a concentration of 8.00E+16cm-2of antimony element, examples 2-2 and 2-7 use silicon substrate with a concentration of 1.00E+16cm-2of antimony element, examples 2-3 and 2-8 use silicon substrate with a concentration of 9.00E+14cm-2of antimony element, examples 2-4 and 2-9 use silicon substrate with a concentration of 8.00E+14cm-2of antimony element, examples 2-5 and 2-10 use silicon substrate with a concentration of 4.00E+14cm-2of antimony element, and based on the thickness of different silicon substrates, the depth of the isolation region of different back contact batteries. -3 -3 -3 -3 -3

[0116] The Isc, Uoc, FF and Eta performance of the solar cells prepared in examples 2-1 to 2-15 were detected by the same method as in example 1, and the results are shown in Tables 3 and 4, respectively.

[0117] Table 3: Results of back contact battery with a thickness of 150 μm

[0118] Table 4: Results of back contact battery with a thickness of 100 μm

[0119] ​​​​​Based on the results of Tables 3 and 4, it can be seen that in the case of back contact cells, i.e. the positive and negative electrodes of the cell are both on one side of the cell, the Isc, Uoc, FF and Eta performance of the solar cell is better when n≥35-1.9lga, and the Isc, Uoc, FF and Eta performance is poorer when the formula is not satisfied.

[0120] In addition, when n satisfies Formula Two, the Isc, Uoc, FF and Eta performance of the solar cell is better, and the reason can be that the carriers not only have to pass through the thickness direction of the silicon substrate, but also generally need to move laterally between the positive and negative electrodes on the back surface. In the process of lateral transport of the carriers, the path is longer, and therefore more grid lines need to be provided per unit length to offset this effect.

[0121] When n satisfies Formula Four, the Isc, Uoc, FF and Eta performance of the solar cell can be further improved.

[0122] For the data in Table 3, the trend graphs of the Eta performance data in the order of increasing grid line density according to this embodiment at different concentrations are shown in Figure 10, and for the data in Table 4, the trend graphs of the Eta performance data in the order of increasing grid line density according to this embodiment at different concentrations are shown in Figure 11. It should be noted that the horizontal coordinates in Figures 10 and 11 only represent the grid line density data sequence according to this embodiment, and have no actual physical meaning.

[0123] In Figures 10 and 11, the data to the left of the vertical dashed line do not satisfy Formula One, and it can be more obviously seen that in the case of not satisfying Formula One, the cell performance decreases rapidly.

[0124] Although the above describes the embodiments of the present application, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and guiding, but not limiting. Those skilled in the art can make many forms under the guidance of this specification and without departing from the scope protected by the claims of the present application, and these all 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 one side surface of the silicon substrate; each of the collector grid lines extends in the same direction; the silicon substrate is doped with an element of antimony, In a direction perpendicular to an extension direction of the collector grid lines, a density of the collector grid lines of the same polarity is n pieces / cm, and a concentration of the antimony element in the silicon substrate is a atoms / cm 3 When n and a satisfy the following relationship: n≥35-klga, wherein k is a constant less than or equal to 2.

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

3. The solar cell of claim 2, wherein, n and a also satisfy the following relationship: n≤35-lga.

4. The solar cell according to any one of claims 1 to 3, wherein The solar cell is a dual-sided contact cell, and k=2.

5. The solar cell according to any one of claims 1 to 3, wherein The solar cell is a back contact cell, and k=1.

9.

6. The solar cell of claim 5, wherein, One side surface of the silicon substrate has an electron collecting region and a hole collecting region, and an isolation region between the electron collecting region and the hole collecting region; when the depth of the isolation region is d μm, the n satisfies the following relationship: 7.The solar cell of claim 6, wherein, a height difference corresponding to an average depth of a bottom of the isolation region from a bottom of a shallower region of the electron collection region and the hole collection region, the bottom of the isolation region being a surface of the silicon substrate corresponding to the isolation region; when the solar cell contains an interface passivation layer, the bottom of the electron collection region or the bottom of the hole collection region is a surface of the interface passivation layer close to the silicon substrate.

8. The solar cell according to any one of claims 1 to 7, wherein The a ranges from 1E13 to 1E18.

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

10. A photovoltaic module, wherein, The photovoltaic module comprises the solar cell according to any one of claims 1-9.

Images