Back contact solar cell, cell assembly and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and provides a back contact solar cell piece, a cell assembly and a photovoltaic system, a silicon substrate of the back contact solar cell piece is provided with a front surface and a back surface which are opposite, and the back surface comprises a first area, a second area and a spacing area located between the first area and the second area. The first hybrid doping layer is disposed on the front surface of the silicon substrate, and the second hybrid doping layer is disposed on the spacer region. Doping elements in the first mixed doping layer and the second mixed doping layer comprise at least one of third main group elements, at least one of fifth main group elements and an oxygen element, and the doping concentration of the doping elements in the first mixed doping layer and the second mixed doping layer is larger than that of the corresponding doping elements in the silicon substrate. Therefore, the surface defects of the silicon substrate can be reduced, the bulk mass of the silicon substrate is effectively improved, and the performance of the back contact solar cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a back-contact solar cell sheet, a cell assembly and a photovoltaic system. Background Art

[0002] With the development of photovoltaic cell technology, the quality of surface passivation has been effectively improved, and defects in the body area of ​​silicon wafers have increasingly become a shortcoming that limits performance. Among them, defects in the body area and near the surface of silicon wafers mainly come from complex phases formed by various metal impurities and complex phases formed by oxygen and various substances. Among them, the introduction of effective impurity absorption technology to gather various metal impurities and oxygen to the surface, creating a clean body area, is conducive to improving the performance of photovoltaic cells. However, the performance of photovoltaic cells in the prior art still needs to be improved. Summary of the invention

[0003] The present application provides a back-contact solar cell sheet, a solar cell assembly and a photovoltaic system.

[0004] The present application is implemented in this way. The back contact solar cell of the embodiment of the present application comprises:

[0005] A silicon substrate having a front surface and a back surface opposite to each other, wherein the back surface includes a first region, a second region, and a spacing region between the first region and the second region;

[0006] A first hybrid doped layer disposed on the front surface; and

[0007] a second mixed doping layer disposed on the spacing region;

[0008] Among them, the first mixed doping layer and the second mixed doping layer are both doped with doping elements, and the doping elements include at least one of the third main group elements, at least one of the fifth main group elements and oxygen element, and the doping concentration of the doping elements in the first mixed doping layer and the second mixed doping layer is greater than the doping concentration of the corresponding doping elements in the silicon substrate.

[0009] In some embodiments, the doping elements in the first mixed doping layer and the second mixed doping layer both include phosphorus, nitrogen, boron, and oxygen.

[0010] In some embodiments, in the first mixed doping layer, the doping concentration of at least one of the phosphorus element, the nitrogen element, and the oxygen element is greater than the doping concentration of the boron element; and / or

[0011] In the second mixed doping layer, a doping concentration of at least one of the phosphorus element, the nitrogen element, and the oxygen element is greater than a doping concentration of the boron element; and / or.

[0012] In some embodiments, the doping element in the silicon substrate includes at least one of the third main group elements; or

[0013] The doping element in the silicon substrate includes at least one of the fifth main group elements; or

[0014] The doping elements in the silicon substrate include at least one of the third main group elements and at least one of the fifth main group elements.

[0015] In some embodiments, the thickness of the first mixed doping layer is 50-600 nm.

[0016] In some embodiments, the thickness of the first mixed doping layer is 50-400 nm.

[0017] In some embodiments, the thickness of the first mixed doping layer is 50-200 nm.

[0018] In some embodiments, the second mixed doping layer has a thickness of 50-600 nm.

[0019] In some embodiments, the second mixed doping layer has a thickness of 50-400 nm.

[0020] In some embodiments, the thickness of the second mixed doping layer is 50-200 nm.

[0021] In some embodiments, in the first mixed doping layer, in a direction from the first mixed doping layer toward the front surface, the doping concentration of each of the doping elements in the first mixed doping layer gradually decreases; or

[0022] In the first mixed doping layer, in a direction from the first mixed doping layer toward the front surface, the doping concentration of each of the doping elements in the first mixed doping layer first increases and then gradually decreases.

[0023] In some embodiments, in the second mixed doping layer, in a direction from the second mixed doping layer toward the back surface, the doping concentration of each of the doping elements in the second mixed doping layer gradually decreases; or

[0024] In the second mixed doping layer, in a direction from the second mixed doping layer toward the back surface, the doping concentration of each of the doping elements in the second mixed doping layer first increases and then gradually decreases.

[0025] In some embodiments, the first mixed doping layer has a first surface opposite to the front surface, and the peak value of the doping concentration of each of the doping elements in the first mixed doping layer is located within a thickness range of 150 nm from the first surface;

[0026] And / or, the second mixed doping layer has a second surface opposite to the back surface, and the peak value of the doping concentration of each of the doping elements in the second mixed doping layer is located within a thickness range of 150 nm from the second surface.

[0027] In some embodiments, the doping element includes phosphorus, boron and oxygen. In the first mixed doping layer, the doping concentration of the phosphorus is greater than 10 16 atoms / cm 3 ; The doping concentration of the boron element is greater than 10 15 atoms / cm 3 ; The doping concentration of the oxygen element is greater than 10 17 atoms / cm 3 .

[0028] In some embodiments, in the first mixed doping layer, the doping concentration of the phosphorus element is 10 16 -10 20 atoms / cm 3 The doping concentration of the boron element is 10 15 -10 18 atoms / cm 3 ; The doping concentration of the oxygen element is 10 17 -10 22 atoms / cm 3 .

[0029] In some embodiments, the doping element includes phosphorus, boron and oxygen. In the second mixed doping layer, the doping concentration of the phosphorus is greater than 10 17 atoms / cm 3 ; The doping concentration of the boron element is greater than 10 15 atoms / cm 3 ; The doping concentration of the oxygen element is greater than 10 17 atoms / cm 3 .

[0030] In some embodiments, in the second mixed doping layer, the doping concentration of the phosphorus element is 10 17 -10 20 atoms / cm 3 ; The doping concentration of the boron element is 10 15 -10 18 atoms / cm 3 ; The doping concentration of the oxygen element is 10 17 -10 22 atoms / cm 3.

[0031] In some embodiments, the peak concentration of each of the doping elements in the first mixed doping layer is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate; and / or

[0032] The peak concentration of each of the doping elements in the second mixed doping layer is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate.

[0033] In some embodiments, in the first mixed doping layer, the difference in doping depth of the peak concentration of each doping element is less than 150 nm; and / or

[0034] In the second mixed doping layer, the difference in doping depth of peak concentrations of the various doping elements is less than 150 nm.

[0035] The present application also provides a battery assembly, which includes a plurality of back-contact solar cells as described in any one of the above items.

[0036] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0037] In the back-contact solar cell, battery assembly and photovoltaic system of the embodiment of the present application, the silicon substrate has a relative front surface and a back surface, the back surface includes a first region, a second region and a spacing region between the first region and the second region, the first mixed doping layer is arranged on the front surface of the silicon substrate, and the second mixed doping layer is arranged on the spacing region. The first mixed doping layer and the second mixed doping layer are both doped with doping elements, and the doping elements include at least one of the third main group elements, at least one of the fifth main group elements and oxygen elements, and the doping concentration of the doping elements in the first mixed doping layer and the second mixed doping layer is greater than the doping concentration of the corresponding doping elements in the silicon substrate. In this way, by combining the high doping of the third main group elements, the fifth main group elements and the oxygen atoms to form the first mixed doping layer and the second mixed doping layer, the surface defects of the silicon substrate can be reduced, and the body quality of the silicon substrate can be effectively improved, thereby improving the performance of the back-contact solar cell.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0040] Figure 2 is a module schematic diagram of a battery assembly provided in an embodiment of the present application;

[0041] Figure 3 is a cross-sectional schematic diagram of a back-contact solar cell provided in an embodiment of the present application;

[0042] Figure 4 is a curve diagram showing the variation of the doping concentration of each doping element with the doping depth in the direction from the front surface to the back surface of the back contact solar cell provided by an embodiment of the present application;

[0043] Figure 5 It is a curve diagram showing the variation of the doping concentration of each doping element in the spacing region with the doping depth in the direction from the back surface to the front surface of the back contact solar cell provided by the embodiment of the present application.

[0044] Description of main component symbols:

[0045] Photovoltaic system 1000, battery assembly 200, back contact solar cell 100, silicon substrate 10, front surface 11, back surface 12, first region 121, second region 122, spacing region 123, first mixed doping layer 20, second mixed doping layer 30, first passivation contact structure 40, first passivation layer 41, first doping layer 42, second passivation contact structure 50, second passivation layer 51, second doping layer 52, front surface passivation layer 60, back surface passivation layer 70, first diffusion layer 80, second diffusion layer 90. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0047] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "lateral", "longitudinal", etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0048] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0049] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0051] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0052] See also Figure 1-Figure 2 The photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, and the battery assembly 200 in the embodiment of the present application may include a plurality of back-contact solar cells 100 in the embodiment of the present application.

[0053] In the embodiment of the present application, the multiple back-contact solar cells 100 in the battery assembly 200 can be connected in series to form multiple battery strings, and each battery string can be connected in series, in parallel, or in series-parallel combination to realize the current bus output. For example, the connection between each battery cell can be realized by welding a welding strip, and the connection between each battery string can be realized by a bus bar. In some embodiments, each battery string can form a battery cell array, and then be packaged together by a front plate, a front adhesive film, a rear adhesive film and a back plate to form a battery assembly 200.

[0054] See also Figure 3-Figure 5 The back-contact solar cell 100 in the embodiment of the present application may include a silicon substrate 10 , a first mixed doping layer 20 , and a second mixed doping layer 30 .

[0055] The silicon substrate 10 has a front surface 11 and a back surface 12 opposite to each other, and the back surface 12 includes a first region 121, a second region 122, and a spacing region 123 between the first region 121 and the second region 122. Specifically, in some embodiments, the back surface 12 may include a plurality of first regions 121, a plurality of second regions 122, and a plurality of spacing regions 123, and the plurality of first regions 121 and the plurality of second regions 122 are alternately arranged in sequence, and the spacing region 123 is between adjacent first regions 121 and second regions 122.

[0056] The first mixed doping layer 20 is disposed on the front surface 11 of the silicon substrate 10, and the second mixed doping layer 30 is disposed on the spacing region 123. The first mixed doping layer 20 and the second mixed doping layer 30 are both doped with doping elements, and the doping elements include at least one of the third main group elements, at least one of the fifth main group elements, and oxygen, and the doping concentrations of the doping elements in the first mixed doping layer 20 and the second mixed doping layer 30 are both greater than the doping concentrations of the corresponding doping elements in the silicon substrate 10.

[0057] It should be noted that the third main group elements include a variety of elements, such as boron, aluminum, gallium, indium, and thallium, and the fifth main group elements also include a variety of elements, such as nitrogen, phosphorus, arsenic, bismuth, and antimony. That is to say, in the embodiment of the present application, the first mixed doping layer 20 and the second mixed doping layer 30 are both doped with at least one of boron, aluminum, gallium, indium, and thallium, at least one of nitrogen, phosphorus, arsenic, bismuth, and antimony, and oxygen. “The doping concentration of each doping element in the first mixed doping layer 20 and the second mixed doping layer 30 is greater than the doping concentration of the corresponding doping element in the silicon substrate 10” means that the doping concentration of the same doping element in the first mixed doping layer 20 and the second mixed doping layer 30 is greater than the doping concentration of the element in the silicon substrate 10. For example, in some embodiments, when the first mixed doping layer 20 and the second mixed doping layer 30 are doped with phosphorus, boron and oxygen, the doping concentration of phosphorus in the first mixed doping layer 20 and the second mixed doping layer 30 is greater than the doping concentration of phosphorus in the silicon substrate 10, the doping concentration of boron in the first mixed doping layer 20 and the second mixed doping layer 30 is greater than the doping concentration of boron in the silicon substrate 10, and the doping concentration of oxygen in the first mixed doping layer 20 and the second mixed doping layer 30 is greater than the doping concentration of oxygen in the silicon substrate 10.

[0058] In the back-contact solar cell 100, the battery assembly 200 and the photovoltaic system 1000 in the embodiments of the present application, the silicon substrate 10 has a front surface 11 and a back surface 12 opposite to each other, the back surface 12 includes a first region 121, a second region 122 and a spacing region 123 between the first region 121 and the second region 122, the first mixed doping layer 20 is disposed on the front surface 11 of the silicon substrate 10, and the second mixed doping layer 30 is disposed on the spacing region 123. The first mixed doping layer 20 and the second mixed doping layer 30 are both doped with doping elements, the doping elements include at least one of the third main group elements, at least one of the fifth main group elements and oxygen, and the doping concentrations of the doping elements in the first mixed doping layer 20 and the second mixed doping layer 30 are both greater than the doping concentrations of the corresponding doping elements in the silicon substrate 10. In this way, by forming a first mixed doping layer 20 and a second mixed doping layer 30 having a higher doping concentration than the silicon substrate 10 on the silicon substrate 10, the high concentration doping of the fifth group element can effectively change the Fermi level, thereby changing the solid solubility of the transition metal in silicon, and achieving the effect of doping in the high concentration area. For example, in some embodiments, the silicon substrate 10 can be heated and then cooled, and the low solid solubility area reaches saturation first. By controlling the cooling rate to control the diffusion rate of impurities, the doping effect of the high concentration area is achieved. The high concentration doping of the third main group element can effectively increase the diffusion coefficient of hydrogen in silicon, wherein hydrogen can passivate defects in the body (including oxygen precipitation, metal polymer precipitation, or various lattice defects), reduce the influence of defects on the recombination, effectively increase the diffusion coefficient of hydrogen in silicon and effectively improve the passivation effect of defects in the body. High concentration doping of oxygen elements can precipitate and getter impurities, forming a local high oxygen region. After heating and cooling, a high oxygen precipitation region is formed locally, thereby introducing a high defect layer. The high defect layer creates conditions for non-uniform nucleation, thereby introducing a high nucleation rate region. When the temperature drops below the solid solubility, due to the different nucleation rates in different regions, the number of interstitial atoms consumed by their precipitation is different, forming an impurity concentration gradient, thereby forming an effective gettering effect. In this way, by combining the high doping of the third main group elements, the fifth main group elements, and oxygen atoms to form the first mixed doping layer 20 and the second mixed doping layer 30, the surface defects of the silicon substrate 10 can be reduced, and the body mass of the silicon substrate 10 can be effectively improved, thereby improving the performance of the back contact solar cell 100.

[0059] Specifically, in the embodiments of the present application, in some embodiments, the first mixed doping layer 20 and the second mixed doping layer 30 can be formed on the silicon substrate 10 by diffusion or the like. In this case, during the manufacturing process, a complete silicon wafer can be provided first, and then diffusion is performed on the silicon wafer to form the first mixed doping layer 20 and the second mixed doping layer 30 in the silicon wafer. In this case, the silicon substrate 10 and the first mixed doping layer 20 and the second mixed doping layer 30 are actually a whole, and the three are respectively a part of the whole. Of course, in other embodiments, the silicon substrate 10 can also be directly provided first, and then the first mixed doping layer 20 and the second mixed doping layer 30 are formed on the silicon substrate 10 by deposition or the like, which is not specifically limited here.

[0060] In addition, if Figure 3 As shown, in the embodiment of the present application, in the back contact solar cell 100, a first passivation contact structure 40 may be provided on the first region 121, and the first passivation contact structure 40 may include a first passivation layer 41 and a first doping layer 42. A second passivation contact structure 50 may be provided on the second region 122, and the second passivation contact structure 50 may include a second passivation layer 51 and a second doping layer 52. The first passivation layer 41 and the second passivation layer 51 may be film layers such as a tunneling layer and an intrinsic amorphous silicon layer. The first doping layer 42 and the second doping layer 52 may be a P-type doping layer and an N-type doping layer, respectively. The first doping layer 42 and the second doping layer 52 are isolated from each other by a spacing region 123. The first mixed doping layer 20 covers the entire front surface 11 of the silicon substrate 10, and the second mixed doping layer 30 is located on the spacing region 123. The spacing region 123 may be a planar structure or a trench structure, which is not specifically limited here.

[0061] Furthermore, if Figure 3 As shown, in an embodiment of the present application, the back-contact solar cell 100 further includes a front surface passivation layer 60 disposed on the first mixed doping layer 20 and a back surface passivation layer 70 stacked to cover the entire back surface 12 (i.e., covering the first passivation contact structure 40, the second passivation contact structure 50 and the second mixed doping layer 30), the first mixed doping layer 20 corresponds to the front surface passivation layer 60, and the back surface passivation layer 70 contacts the second mixed doping layer 30 at the spacing region 123.

[0062] In addition, in some embodiments, a first diffusion layer 80 may be provided on the first region 121, and the first diffusion layer 80 is located between the first passivation layer 41 and the back surface 12. The first diffusion layer 80 is an inner diffusion layer formed in the process of depositing the first doping layer 42, and its polarity is the same as that of the first doping layer 42. A second diffusion layer 90 may be provided on the second region 122, and the second diffusion layer 90 is located between the first passivation layer 41 and the back surface 12. The second diffusion layer 90 is a diffusion layer formed in the process of depositing the second doping layer 52, and its polarity is the same as that of the second doping layer 52. That is to say, in some embodiments, the first diffusion layer 80 is provided on the first region 121, and the first passivation contact structure 40 is located on the first diffusion layer 80. The second diffusion layer 90 is provided on the second region 122, and the second passivation contact structure 50 is located on the first diffusion layer 80. The second mixed doping layer 30 is provided on the spacing region 123.

[0063] Furthermore, if Figure 5 As shown, in the embodiment of the present application, the doping elements in the first mixed doping layer 20 and the second mixed doping layer 30 both include phosphorus (P), nitrogen (N), boron (B) and oxygen (O).

[0064] In this way, by using high concentrations of phosphorus, nitrogen, boron and oxygen in the first mixed doping layer 20 and the second mixed doping layer 30 , the performance of the back contact solar cell 100 can be improved.

[0065] Furthermore, in some embodiments, in the first mixed doping layer 20, the doping concentration of at least one of phosphorus, nitrogen and oxygen is greater than the doping concentration of boron, preferably the doping concentrations of phosphorus, nitrogen and oxygen are all greater than the doping concentration of boron.

[0066] In this way, the concentration of at least one of the phosphorus element, nitrogen element and oxygen element in the first mixed doping layer 20 is set higher, and the doping concentration of the boron element is set lower, which can further enhance the doping effect and surface passivation effect on one side of the back contact solar cell 100, improve the body quality, and thus further enhance the performance of the back contact solar cell 100.

[0067] In some embodiments, in the second mixed doping layer 30 , the doping concentration of at least one of phosphorus, nitrogen and oxygen is greater than the doping concentration of boron, preferably the doping concentrations of phosphorus, nitrogen and oxygen are all greater than the doping concentration of boron.

[0068] In this way, the concentration of at least one of the phosphorus element, nitrogen element and oxygen element in the second mixed doping layer 30 is set higher, and the doping concentration of the boron element is set lower, which can further enhance the doping effect and surface passivation effect on the other side of the back contact solar cell 100, improve the body quality, and thus further enhance the performance of the back contact solar cell 100.

[0069] In some embodiments, the silicon substrate 10 may be a P-type silicon substrate 10, an N-type silicon substrate 10, or a combination of a P-type and an N-type silicon substrate 10. Specifically, when the silicon substrate 10 is a P-type silicon substrate 10, the doping element in the silicon substrate 10 includes at least one of the third main group elements, such as boron. Of course, in such a case, in some embodiments, the silicon substrate 10 may also include at least one of nitrogen and oxygen.

[0070] When the silicon substrate 10 is an N-type silicon substrate 10, the doping element in the silicon substrate 10 includes at least one of the fifth main group elements, such as phosphorus. Of course, in this case, in some embodiments, the silicon substrate 10 may also include at least one of nitrogen and oxygen.

[0071] When the silicon substrate 10 is a P-type and N-type combined silicon substrate 10, the doping elements in the silicon substrate 10 include at least one of the third doping elements and at least one of the fifth main group elements. Of course, in some embodiments, it may also include at least one of nitrogen and oxygen.

[0072] In some embodiments, the thickness of the first mixed doping layer 20 may be 50 nm-600 nm.

[0073] Thus, by setting the thickness of the first mixed doping layer 20 within this reasonable range, it is possible to avoid the first mixed doping layer 20 being too thick to form effective doping in the center of the silicon substrate 10, and it is also possible to avoid the first mixed doping layer 20 being too thin to result in poor passivation effect and low efficiency.

[0074] Specifically, in such an embodiment, the thickness of the first mixed doping layer 20 may be, for example, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm or any value between 50nm-600nm.

[0075] Further, in such an embodiment, the thickness of the first hybrid doping layer 20 is preferably 50nm-400nm, and most preferably 50nm-200nm. Thus, setting the thickness of the first hybrid doping layer 20 within the preferred range of 50nm-200nm can better balance the contradiction between the gettering and passivation effects, and further optimize the performance of the back contact solar cell 100.

[0076] In some embodiments, the thickness of the second mixed doping layer 30 may be 50 nm-600 nm.

[0077] Thus, by setting the thickness of the second mixed doping layer 30 within this reasonable range, it is possible to avoid the second mixed doping layer 30 being too thick to form effective doping in the center of the silicon substrate 10, and it is also possible to avoid the second mixed doping layer 30 being too thin to result in poor passivation effect and low efficiency.

[0078] Specifically, in such an embodiment, the thickness of the second mixed doping layer 30 may be, for example, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm or any value between 50nm-600nm.

[0079] Further, in such an embodiment, the thickness of the second hybrid doping layer 30 is preferably 50nm-400nm, and most preferably 50nm-200nm. Thus, setting the thickness of the second hybrid doping layer 30 within the preferred range of 50nm-200nm can better balance the contradiction between the gettering and passivation effects, and further optimize the performance of the back contact solar cell 100.

[0080] See also Figure 4 , Figure 4 The graph shown is a curve of the doping concentration of each doping element versus doping depth in the direction from the front surface 11 to the back surface 12 in the back contact solar cell 100. Figure 4 In FIG. 1 , the A region represents the first mixed doping layer 20, the B region represents the silicon substrate 10, and the region on the left side of the A region is the front surface passivation layer 60. Figure 4 As shown, in some embodiments, in the first mixed doping layer 20 , in a direction from the first mixed doping layer 20 toward the front surface 11 , the doping concentration of each doping element in the first mixed doping layer 20 gradually decreases.

[0081] Thus, the first mixed doping layer 20 can form a gradient concentration on the side where the front surface 11 is located, so that impurities can be effectively transported to the side near the surface (ie, the side of the first mixed doping layer 20 facing away from the front surface 11), thereby improving the impurity gettering effect.

[0082] Of course, in some embodiments, it may also be that: in the first mixed doping layer 20 , in the direction from the first mixed doping layer 20 toward the front surface 11 , the doping concentration of each doping element in the first mixed doping layer 20 first increases and then gradually decreases.

[0083] In this way, a gradient concentration can also be formed on the side of the front surface 11, so that impurities can be effectively transported to the side close to the surface, thereby improving the impurity absorption effect. At the same time, the doping concentration peak of each element in the first mixed doping layer 20 can be located inside the first mixed doping layer 20, thereby avoiding the surface impurity concentration of the first mixed doping layer 20 being too high and introducing more surface defects to affect the passivation effect.

[0084] See also Figure 5 , Figure 5 The graph shown is a curve of the doping concentration of each doping element in the spacing region 123 as a function of the doping depth in the direction from the back surface 12 to the front surface 11 in the back contact solar cell 100. Figure 5 In FIG. 1 , the C region represents the second mixed doping layer 30, the D region represents the silicon substrate 10, and the region on the left side of the C region is the back surface passivation layer 70. Figure 5 As shown, in some embodiments, in the second mixed doping layer 30 , in a direction from the second mixed doping layer 30 toward the back surface 12 , the doping concentration of each doping element in the second mixed doping layer 30 gradually decreases.

[0085] Thus, the second mixed doping layer 30 can form a gradient concentration on the side where the back surface 12 is located, so that impurities can be effectively transported to the side near the surface (ie, the side of the second mixed doping layer 30 facing away from the back surface 12), thereby improving the impurity gettering effect.

[0086] Of course, in some embodiments, it may also be that: in the second mixed doping layer 30 , in the direction from the second mixed doping layer 30 toward the back surface 12 , the doping concentration of each doping element in the second mixed doping layer 30 first increases and then gradually decreases.

[0087] In this way, a gradient concentration can also be formed on the side of the back surface 12, so that impurities can be effectively transported to the side close to the surface, thereby improving the impurity absorption effect. At the same time, the doping concentration peak of each element in the second mixed doping layer 30 can be located inside the second mixed doping layer 30, thereby avoiding the surface impurity concentration of the second mixed doping layer 30 being too high and introducing more surface defects to affect the passivation effect.

[0088] See also Figure 3 In some embodiments, the first mixed doping layer 20 has a first surface 21 opposite to the front surface 11, and the peak value (i.e., peak concentration) of the doping concentration of each doping element in the first mixed doping layer 20 is located within a thickness range of 150 nm from the first surface 21. That is, in the first mixed doping layer 20, the distance between the depth position where the peak value of the doping concentration of each doping element is located and the surface of the first mixed doping layer 20 away from the front surface passivation layer 60 is less than or equal to 150 nm. That is, the depth at which the highest peak value of the doping concentration of each doping element is located is within a thickness range of 150 nm from the surface of the first mixed doping layer 20 away from the silicon substrate 10.

[0089] In this way, a doping peak can be created on the side where the front surface 11 of the silicon substrate 10 is located, taking into account the impurity gettering effect and surface passivation of the silicon substrate 10 while avoiding excessive surface impurity content that may affect the introduction of surface defects and affect surface passivation.

[0090] See also Figure 3 In some embodiments, the second mixed doping layer 30 has a second surface 31 opposite to the back surface 12, and the peak value of the doping concentration of each doping element in the second mixed doping layer 30 is located within a thickness range of 150 nm from the second surface 31. That is, in the second mixed doping layer 30, the distance between the depth position where the peak value of the doping concentration of each doping element is located and the surface of the second mixed doping layer 30 away from the back surface passivation layer 70 is less than or equal to 150 nm, that is, the depth at which the highest peak value of the doping concentration of each doping element is located is within a thickness range of 150 nm from the surface of the second mixed doping layer 30 away from the silicon substrate 10.

[0091] In this way, a doping peak can be created on the side of the back surface 12 of the silicon substrate 10 where the spacing region 123 is located, taking into account both the impurity gettering effect and surface passivation of the silicon substrate 10 while avoiding excessive surface impurity content that may affect the introduction of surface defects and affect surface passivation.

[0092] See also Figure 4 In some embodiments, the doping elements include phosphorus, boron and oxygen. In the first mixed doping layer 20, the doping concentration of phosphorus is greater than 10 16 atoms / cm 3 ; The doping concentration of boron is greater than 10 15 atoms / cm 3 ; The doping concentration of oxygen element is greater than 10 17 atoms / cm 3 .

[0093] In this way, setting the doping concentrations of the three elements in the first mixed doping layer 20 to be greater than the above values ​​can further enhance the surface gettering effect and further improve the performance of the back contact solar cell 100 .

[0094] Furthermore, if Figure 4 As shown, in such an embodiment, in the first mixed doping layer 20, the doping concentration of phosphorus element is preferably 10 16 -10 20 atoms / cm 3 The doping concentration of boron is preferably 10 15 -10 18 atoms / cm 3 ; The doping concentration of oxygen element is preferably 10 17 -10 22 atoms / cm 3 .

[0095] Thus, by setting the doping concentrations of the three elements in the first mixed doping layer 20 within the above-mentioned preferred range, it is possible to improve the doping effect while avoiding the introduction of larger Auger recombination and larger defect recombination near the surface of the first mixed doping layer 20.

[0096] Specifically, in such an embodiment, in the first mixed doping layer 20, the doping concentration of phosphorus element may be, for example, 10 16 atoms / cm 3 , 10 17 atoms / cm 3 , 10 18 atoms / cm 3 , 10 19 atoms / cm 3 , 10 12 atoms / cm 3 The doping concentration of the boron element may be, for example, 10 15 atoms / cm 3 , 10 16 atoms / cm 3 , 10 17 atoms / cm 3 , 10 18 atoms / cm 3 The doping concentration of oxygen element may be, for example, 10 17 atoms / cm 3 , 10 18 atoms / cm 3 , 10 19 atoms / cm 3 , 10 20 atoms / cm3 , 10 21 atoms / cm 3 , 10 22 atoms / cm 3 .

[0097] See also Figure 5 In some embodiments, the doping elements include phosphorus, boron and oxygen. In the second mixed doping layer 30, the doping concentration of phosphorus is greater than 10 17 atoms / cm 3 ; The doping concentration of boron is greater than 10 15 atoms / cm 3 ; The doping concentration of oxygen element is greater than 10 17 atoms / cm 3 .

[0098] In this way, setting the doping concentrations of the three elements in the second mixed doping layer 30 to be greater than the above values ​​can further enhance the surface gettering effect and further improve the performance of the back contact solar cell 100 .

[0099] Furthermore, in such an embodiment, in the second mixed doping layer 30, the doping concentration of phosphorus is preferably 10 17 -10 20 atoms / cm 3 The doping concentration of boron is preferably 10 15 -10 18 atoms / cm 3 ; The doping concentration of oxygen element is preferably 10 17 -10 22 atoms / cm 3 .

[0100] Thus, by setting the doping concentrations of the three elements in the second mixed doping layer 30 within the above preferred range, it is possible to improve the doping effect while avoiding the introduction of larger Auger recombination and larger defect recombination near the surface of the second mixed doping layer 30 .

[0101] Specifically, in such an embodiment, in the second mixed doping layer 30, the doping concentration of phosphorus element may be, for example, 10 16 atoms / cm 3 , 10 17 atoms / cm 3 , 10 18 atoms / cm 3 , 10 19 atoms / cm 3 , 10 12 atoms / cm3 The doping concentration of the boron element may be, for example, 10 15 atoms / cm 3 , 10 16 atoms / cm 3 , 10 17 atoms / cm 3 , 10 18 atoms / cm 3 ; The doping concentration of oxygen element may be, for example, 10 17 atoms / cm 3 , 10 18 atoms / cm 3 , 10 19 atoms / cm 3 , 10 20 atoms / cm 3 , 10 21 atoms / cm 3 , 10 22 atoms / cm 3 .

[0102] See also Figure 4 and Figure 5 In some embodiments, at the same doping depth of the first hybrid doping layer 20 and the second hybrid doping layer 30, the doping concentration of phosphorus in the second hybrid doping layer 30 is greater than the doping concentration of phosphorus in the first hybrid doping layer 20, and the doping concentration of boron in the first hybrid doping layer 20 is greater than the doping concentration of boron in the second hybrid doping layer 30. The doping depth of the first hybrid doping layer 20 refers to the distance between any position in the first hybrid doping layer 20 and the surface of the first hybrid doping layer 20 away from the silicon substrate 10, and the doping depth of the second hybrid doping layer 30 refers to the distance between any position in the second hybrid doping layer 30 and the surface of the second hybrid doping layer 30 away from the silicon substrate 10, and the “same doping depth” means that the distance values ​​of the two are the same.

[0103] In this way, by introducing a higher concentration of phosphorus doping on the back surface 12 side and a higher concentration of boron doping on the front surface 11 side, the performance of the back contact solar cell 100 can be further optimized.

[0104] In some embodiments, the peak concentration of each doping element in the first mixed doping layer 20 is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate 10 .

[0105] In this way, by increasing the concentration of the doping elements in the first mixed doping layer 20 to more than 10 times, the surface doping effect can be effectively guaranteed to avoid the difference between the doping concentration in the first mixed doping layer 20 and the doping concentration in the silicon substrate 10 being too small, resulting in poor doping effect.

[0106] In some embodiments, the peak concentration of each doping element in the second mixed doping layer 30 is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate 10 .

[0107] Thus, by increasing the concentration of the doping elements in the second mixed doping layer 30 to more than 10 times, the surface gettering effect can be effectively guaranteed, avoiding the poor gettering effect caused by the difference between the doping concentration in the second mixed doping layer 30 and the doping concentration in the silicon substrate 10 being too small.

[0108] In some embodiments, in the first mixed doping layer 20, the difference in doping depth of the peak concentration of each doping element is less than 150nm. It should be noted that in such an embodiment, "peak concentration" refers to the maximum doping concentration of each doping element, and "doping depth of peak concentration" refers to the distance between the location of the peak concentration and the surface of the first mixed doping layer 20 facing away from the silicon substrate 10.

[0109] In this way, by controlling the depth of the peak concentration of each element within this smaller range, the range of the gettering region of the first mixed doping layer 20 can be minimized, defects can be more concentrated, and the influence of the gettering region itself on the performance can be reduced.

[0110] In some embodiments, in the second mixed doping layer 30, the difference in doping depth of the peak concentration of each doping element is also less than 150nm. It should be noted that in such an embodiment, "peak concentration" refers to the maximum doping concentration of each doping element, and "doping depth of peak concentration" refers to the distance between the location of the peak concentration and the surface of the second mixed doping layer 30 facing away from the silicon substrate 10.

[0111] In this way, by controlling the depth of the peak concentration of each element within this smaller range, the range of the gettering region of the second mixed doping layer 30 can be minimized, defects can be more concentrated, and the influence of the gettering region itself on the performance can be reduced.

[0112] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0113] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate having a front surface and a back surface opposite to each other, wherein the back surface includes a first region, a second region, and a spacing region between the first region and the second region; a first hybrid doped layer disposed on the front surface; and a second mixed doping layer disposed on the spacing region; Among them, the first mixed doping layer and the second mixed doping layer are both doped with doping elements, and the doping elements include at least one of the third main group elements, at least one of the fifth main group elements and oxygen element, and the doping concentration of the doping elements in the first mixed doping layer and the second mixed doping layer is greater than the doping concentration of the corresponding doping elements in the silicon substrate.

2. The back contact solar cell according to claim 1, characterized in that: The doping elements in the first mixed doping layer and the second mixed doping layer both include phosphorus, nitrogen, boron and oxygen.

3. The back contact solar cell according to claim 2, characterized in that: In the first mixed doping layer, a doping concentration of at least one of the phosphorus element, the nitrogen element, and the oxygen element is greater than a doping concentration of the boron element; and / or In the second mixed doping layer, a doping concentration of at least one of the phosphorus element, the nitrogen element, and the oxygen element is greater than a doping concentration of the boron element; and / or.

4. The back contact solar cell according to claim 1, characterized in that: The doping element in the silicon substrate includes at least one of the third main group elements; or The doping element in the silicon substrate includes at least one of the fifth main group elements; or The doping elements in the silicon substrate include at least one of the third main group elements and at least one of the fifth main group elements.

5. The back contact solar cell according to claim 1, characterized in that: The thickness of the first mixed doping layer is 50-600 nm.

6. The back contact solar cell according to claim 5, characterized in that: The thickness of the first mixed doping layer is 50-400 nm.

7. The back contact solar cell according to claim 6, characterized in that: The thickness of the first mixed doping layer is 50-200 nm.

8. The back contact solar cell according to claim 1, characterized in that: The thickness of the second mixed doping layer is 50-600 nm.

9. The back contact solar cell according to claim 8, characterized in that: The thickness of the second mixed doping layer is 50-400 nm.

10. The back contact solar cell according to claim 9, characterized in that: The thickness of the second mixed doping layer is 50-200 nm.

11. The back contact solar cell according to claim 1, characterized in that: In the first mixed doping layer, in a direction from the first mixed doping layer toward the front surface, the doping concentration of each of the doping elements in the first mixed doping layer gradually decreases; or In the first mixed doping layer, in a direction from the first mixed doping layer toward the front surface, the doping concentration of each of the doping elements in the first mixed doping layer first increases and then gradually decreases.

12. The back contact solar cell according to claim 1, characterized in that: In the second mixed doping layer, in a direction from the second mixed doping layer toward the back surface, the doping concentration of each of the doping elements in the second mixed doping layer gradually decreases; or In the second mixed doping layer, in a direction from the second mixed doping layer toward the back surface, the doping concentration of each of the doping elements in the second mixed doping layer first increases and then gradually decreases.

13. The back contact solar cell according to claim 1, characterized in that: The first mixed doping layer has a first surface opposite to the front surface, and the peak value of the doping concentration of each of the doping elements in the first mixed doping layer is located within a thickness range of 150 nm from the first surface; And / or, the second mixed doping layer has a second surface opposite to the back surface, and the peak value of the doping concentration of each of the doping elements in the second mixed doping layer is located within a thickness range of 150 nm from the second surface.

14. The back contact solar cell according to claim 1, characterized in that: The doping elements include phosphorus, boron and oxygen. In the first mixed doping layer, the doping concentration of the phosphorus is greater than 10 16 atoms / cm 3 ; The doping concentration of the boron element is greater than 10 15 atoms / cm 3 ; The doping concentration of the oxygen element is greater than 10 17 atoms / cm 3 .

15. The back contact solar cell according to claim 14, characterized in that: In the first mixed doping layer, the doping concentration of the phosphorus element is 10 16 -10 20 atoms / cm 3 ; The doping concentration of the boron element is 10 15 -10 18 atoms / cm 3 ; The doping concentration of the oxygen element is 10 17 -10 22 atoms / cm 3 .

16. The back contact solar cell according to claim 1, characterized in that: The doping elements include phosphorus, boron and oxygen. In the second mixed doping layer, the doping concentration of the phosphorus is greater than 10 17 atoms / cm 3 ; The doping concentration of the boron element is greater than 10 15 atoms / cm 3 ; The doping concentration of the oxygen element is greater than 10 17 atoms / cm 3 .

17. The back contact solar cell according to claim 16, characterized in that: In the second mixed doping layer, the doping concentration of the phosphorus element is 10 17 -10 20 atoms / cm 3 ; The doping concentration of the boron element is 10 15 -10 18 atoms / cm 3 ; The doping concentration of the oxygen element is 10 17 -10 22 atoms / cm 3 .

18. The back contact solar cell according to claim 1, characterized in that: The peak concentration of each of the doping elements in the first mixed doping layer is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate; and / or The peak concentration of each of the doping elements in the second mixed doping layer is more than 10 times the peak concentration of the corresponding doping element in the silicon substrate.

19. The back contact solar cell according to claim 1, characterized in that: In the first mixed doping layer, the difference in doping depth of the peak concentration of each doping element is less than 150 nm; and / or In the second mixed doping layer, the difference in doping depth of peak concentrations of the various doping elements is less than 150 nm.

20. A battery assembly, characterized in that: A back-contact solar cell comprising the back-contact solar cell according to any one of claims 1 to 19.

21. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 20.

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