Solar cell and photovoltaic module

Abstract

This application relates to the field of solar cells, and particularly to a solar cell and photovoltaic module. The solar cell includes: a substrate; a tunneling dielectric layer and a doped conductive layer located on the surface of the substrate, the tunneling dielectric layer being located between the doped conductive layer and the substrate, the doped conductive layer containing a dopant element, the dopant element being N-type or P-type, the doped conductive layer having a plurality of spaced-apart first heavily doped regions extending along a first direction, the doping concentration in the first heavily doped regions being greater than the doping concentration in the doped conductive layer excluding the first heavily doped regions; a passivation layer located on the surface of the doped conductive layer away from the substrate; and a plurality of spaced-apart electrodes extending along a second direction, the electrodes penetrating the passivation layer and contacting the doped conductive layer, with at least two first heavily doped regions contacting the same electrode. This application embodiment is beneficial for improving the photoelectric conversion efficiency of passivated contact solar cells.

Description

Technical Field

[0001] This application relates to the field of solar cells, and particularly to a solar cell and a photovoltaic module. Background Technology

[0002] Factors affecting the performance of solar cells (such as photoelectric conversion efficiency) include optical losses and electrical losses. Optical losses include reflection losses from the front surface of the cell, shading losses from the contact grid lines, and non-absorption losses in the long wavelength range. Electrical losses include photogenerated carrier recombination on the semiconductor surface and within the cell, contact resistance between the semiconductor and metal grid lines, and contact resistance between the metal and semiconductor.

[0003] To reduce electrical losses in solar cells, a tunneling oxide passivation metal contact structure can be formed on the cell surface. This structure consists of an ultrathin tunneling dielectric layer and a doped conductive layer. This structure provides excellent surface passivation, thereby reducing metal contact recombination current and improving the cell's open-circuit voltage and short-circuit current. While the tunneling oxide passivation metal contact structure can optimize solar cell performance, many factors still influence the performance of this type of solar cell. Therefore, developing high-efficiency passivated contact solar cells is of great significance. Summary of the Invention

[0004] This application provides a solar cell and a photovoltaic module, which are beneficial for improving the photoelectric conversion efficiency of passivated contact solar cells.

[0005] One embodiment of this application provides a solar cell, comprising: a substrate; a tunneling dielectric layer and a doped conductive layer located on the surface of the substrate, the tunneling dielectric layer being located between the doped conductive layer and the substrate, the doped conductive layer containing a dopant element of N-type or P-type, the doped conductive layer having a plurality of spaced-apart first heavily doped regions extending along a first direction, the doping concentration in the first heavily doped regions being greater than the doping concentration in the doped conductive layer excluding the first heavily doped regions; a passivation layer located on the surface of the doped conductive layer away from the substrate; and a plurality of spaced-apart electrodes extending along a second direction, the electrodes penetrating the passivation layer and contacting the doped conductive layer, with at least two first heavily doped regions contacting the same electrode.

[0006] In addition, in the direction perpendicular to the surface of the substrate, the depth of the first doped region is less than or equal to the thickness of the doped conductive layer outside the first doped region.

[0007] In addition, the ratio of the depth of the first doped region to the thickness of the doped conductive layer ranges from 80% to 100%.

[0008] In addition, the substrate has a second doped region, the doping concentration of which is greater than the doping concentration of the substrate excluding the second doped region, and the first doped region is aligned with the second doped region and the doping elements are of the same type.

[0009] In addition, the doping concentration in the second doping region is less than or equal to the doping concentration in the first doping region.

[0010] In addition, the dopant ion concentration in the first doped region is 2E+20cm. -3 ~2E+21cm -3 .

[0011] In addition, the depth of the second heavily doped region in the direction perpendicular to the substrate surface ranges from 0.001 μm to 1 μm.

[0012] In addition, the tunneling dielectric layer has a third doped region that extends through the thickness of the tunneling dielectric layer. One end of the third doped region is in contact with the first doped region, and the other end of the third doped region is in contact with the second doped region. The doped ions in the first doped region, the second doped region, and the third doped region are of the same type and are directly opposite each other.

[0013] In addition, along the arrangement direction of the multiple first-level doped regions, the width of the first-level doped region is smaller than the width of the second-level doped region; the width of the first-level doped region is less than or equal to the width of the third-level doped region.

[0014] In addition, the ratio of the total surface area of ​​the first doped region to the surface area of ​​the doped conductive layer ranges from 1% to 20%.

[0015] In addition, along the arrangement direction of the multiple first-doped regions, the width of the first-doped region is 20μm to 100μm.

[0016] In addition, along the arrangement direction of the multiple first doped regions, the spacing between adjacent first heavily doped regions ranges from 0.8 mm to 4 mm.

[0017] In addition, the materials used to dop the conductive layer include at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0018] In addition, the substrate has a first surface and a second surface disposed opposite to each other, and the tunneling dielectric layer and the doped conductive layer are located on the first surface side and / or the second surface side of the substrate.

[0019] In addition, the type of dopant element in the substrate is the same as the type of dopant element in the conductive layer.

[0020] Accordingly, another aspect of this application provides a photovoltaic module, including: a battery string, formed by connecting a plurality of solar cells as described above; an encapsulating film for covering the surface of the battery string; and a cover plate for covering the surface of the encapsulating film facing away from the battery string.

[0021] The technical solution provided in this application has at least the following advantages:

[0022] In the solar cell technical solution provided in this application embodiment, the doped conductive layer has multiple spaced-apart first doped regions, the doping concentration in the first doped regions being greater than the doping concentration in the doped conductive layer excluding the first doped regions; multiple spaced-apart electrodes, with at least two first doped regions in contact with the same electrode. Thus, the doped conductive layer can be divided into first doped regions and regions excluding the first doped regions. That is, the doping concentration and doping depth of the first doped regions can be appropriately set without affecting the doping concentration and thickness of the doped conductive layer excluding the first doped regions. This is beneficial for reducing the sheet resistance and optical absorption of the doped conductive layer, thereby improving the photoelectric conversion efficiency of the solar cell. The doped conductive layer has multiple spaced-apart first doped regions, the doping ion concentration in the first doped regions being greater than the doping ion concentration in the doped conductive layer excluding the first doped regions, and the number of majority carriers in the first doped regions being greater than the number of majority carriers in the regions excluding the first doped regions. This increases the current transmission capability, thereby reducing the series resistance of the solar cell and improving the photoelectric conversion efficiency. At least two first-doped regions are in contact with the same electrode. The first-doped region with a higher doping concentration forms a good ohmic contact with the electrode. The contact resistance between the first-doped region with a higher doping concentration and the electrode is lower than the contact resistance between the doped conductive layer other than the first-doped region and the electrode. The current conduction effect is better, which is beneficial to improving the photoelectric conversion efficiency. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 This is a schematic diagram of a solar cell provided in one embodiment of this application;

[0025] Figure 2 This is a partial structural schematic diagram of a solar cell provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram of another partial structure of a solar cell provided in an embodiment of this application;

[0027] Figure 4 ECV doping curve of a solar cell provided in an embodiment of this application;

[0028] Figure 5 A schematic diagram of a solar cell provided in another embodiment of this application;

[0029] Figure 6 A schematic diagram of a solar cell provided in yet another embodiment of this application;

[0030] Figure 7 This is a schematic diagram of a solar cell provided in another embodiment of the present application;

[0031] Figures 8 to 16 This is a schematic diagram of the structure corresponding to each step in the fabrication method of a solar cell provided in an embodiment of this application. Detailed Implementation

[0032] As can be seen from the background technology, the photoelectric conversion efficiency of passivated contact solar cells still needs to be further optimized and improved.

[0033] Therefore, this application provides a solar cell and its fabrication method, as well as a photovoltaic module. Multiple first-doped regions are formed at intervals within the doped conductive layer of the solar cell. These first-doped regions extend along a first direction, and their doping concentration is greater than the doping concentration of the conductive layer excluding the first-doped regions. At least two of the first-doped regions are in contact with the same electrode. This increases the doping concentration within the conductive layer, improving current transmission capability and reducing the sheet resistance of the conductive layer, which helps reduce open-circuit voltage and thus improves photoelectric conversion efficiency. The higher doping concentration within the first-doped regions, and the fact that at least two of the first-doped regions are in contact with the same electrode, creates a good ohmic contact between the conductive layer and the electrode, reducing the contact resistance between the conductive layer and the electrode and further improving the photoelectric conversion efficiency of the solar cell. Simultaneously, increasing the spacing between the electrodes reduces the amount of electrode material used, saving production costs, and also increases the light-receiving surface area of ​​the solar cell, thereby improving photoelectric conversion efficiency.

[0034] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0035] refer to Figures 1 to 4 , Figure 1 This is a schematic diagram of a solar cell provided in one embodiment of this application; Figure 2 This is a partial structural schematic diagram of a solar cell provided in an embodiment of this application; Figure 3 This is a schematic diagram of another partial structure of a solar cell provided in an embodiment of this application; Figure 4ECV doping curve of a solar cell provided in an embodiment of this application.

[0036] One embodiment of this application provides a solar cell, such as Figure 2 As shown, it includes: a substrate 100; a tunneling dielectric layer 140 and a doped conductive layer 150 located on the surface of the substrate 100, the tunneling dielectric layer 140 being located between the doped conductive layer 150 and the substrate 100, the doped conductive layer 150 containing a dopant element of type N-type or P-type, the doped conductive layer 150 having a plurality of spaced-apart first heavily doped regions 151 extending along a first direction, the doping concentration in the first heavily doped regions 151 being greater than the doping concentration in the doped conductive layer 150 excluding the first heavily doped regions 151; a passivation layer 160 located on the surface of the doped conductive layer 150 away from the substrate 100; a plurality of spaced-apart electrodes 170 extending along a second direction, each electrode 170 penetrating the passivation layer 160 and contacting the doped conductive layer 150, and at least two first heavily doped regions 151 contacting the same electrode 170.

[0037] In some embodiments, the solar cell is a tunnel oxide passivated contact (TOPCon) cell, which may include a double-sided tunnel oxide passivated contact cell or a single-sided tunnel oxide passivated contact cell.

[0038] The substrate 100 is a region that absorbs incident photons to generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate 100, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon; in other embodiments, the material of the substrate 100 may also be silicon carbide, organic materials, or multi-component compounds. Multi-component compounds may include, but are not limited to, materials such as perovskite, gallium arsenide, cadmium telluride, and copper indium selenide. Exemplarily, in this application, the substrate 100 is a monocrystalline silicon substrate.

[0039] In some embodiments, the substrate 100 has a first surface 101 and a second surface 102 disposed opposite to each other. The first surface 101 of the substrate 100 is referred to as the front surface, and the second surface 102 of the substrate 100 is referred to as the rear surface. Further, for a single-sided battery, the first surface 101 of the substrate 100 is the light-receiving surface, and the second surface 102 of the substrate 100 is the back-lighting surface; for a bi-sided battery, both the first surface 101 and the second surface 102 can serve as light-receiving surfaces to absorb incident light.

[0040] In some embodiments, the substrate 100 contains dopant elements of either N-type or P-type. N-type elements can be group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As), while P-type elements can be group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In). For example, when the substrate 100 is a P-type substrate, the internal dopant element type is P-type. Similarly, when the substrate 100 is an N-type substrate, the internal dopant element type is N-type.

[0041] In some embodiments, the doping element type in the substrate 100 and the doping element type in the conductive layer 150 can be the same. For example, the doping element type in the substrate 100 is N-type, and the doping element type in the conductive layer 150 is N-type.

[0042] In some embodiments, the solar cell includes an emitter 110 located on the first surface 101 side of the substrate 100. The substrate 100 and the emitter 110 form a PN junction; for example, the substrate 100 contains N-type doped elements, and the emitter 110 contains P-type doped elements. In other embodiments, the emitter 110 can be considered as part of the substrate 100, or as an extension of the substrate 100. Furthermore, the surface of the emitter 110 can be configured as a pyramidal textured surface to reduce light reflection, increase light absorption and utilization, and improve the conversion efficiency of the solar cell.

[0043] In some embodiments, the tunneling dielectric layer 140 and the doped conductive layer 150 are located on the second surface 102 side of the substrate 100. The tunneling dielectric layer 140 reduces the interface state density between the substrate 100 and the doped conductive layer 150 through chemical passivation, thereby reducing minority carrier recombination and helping to reduce the Jo load current. The tunneling dielectric layer 140 allows majority carriers to tunnel into the doped conductive layer 150, and then the majority carriers are laterally transported in the doped conductive layer 150 and collected by the electrode 170, thereby greatly reducing the contact recombination current between the electrode 170 and the doped conductive layer 150 and improving the open-circuit voltage and short-circuit current of the solar cell.

[0044] In some embodiments, the material of the tunneling dielectric layer 140 may include, but is not limited to, dielectric materials with tunneling properties such as silicon oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, and intrinsic polycrystalline silicon. The thickness of the tunneling dielectric layer 140 may be 0.5 nm to 2 nm, optionally, the thickness of the tunneling dielectric layer 140 may be 0.5 nm to 1.5 nm, and further, the thickness of the tunneling dielectric layer 140 may be 0.5 nm to 1.2 nm.

[0045] The doping concentration and depth of the conductive layer 150 affect the photoelectric conversion efficiency of the solar cell. When the doping concentration and depth of the conductive layer 150 are within an appropriate range, it can ensure that the conductive layer 150 and the electrode 170 form a good ohmic contact, so that the majority carriers can be effectively transported, that is, the solar cell has a high conversion efficiency. At the same time, it can ensure that the recombination loss on the surface of the substrate 100 is small and the interface passivation effect of the tunneling dielectric layer 140 is achieved, thereby improving the conversion efficiency of the solar cell.

[0046] Methods for detecting impurity concentration distribution may include extended resistance method, capacitance-voltage method (CV), secondary ion mass spectrometry (SIMS), differential Hall effect, and electrochemical capacitance-voltage method (ECV). In some embodiments, the range of doping concentration and depth of the doped conductive layer 150 is detected by electrochemical capacitance-voltage method. (Reference) Figure 4 The relationship between the doping concentration and depth of the doped conductive layer 150 in the solar cell of this application conforms to... Figure 4 The ECV doping curves of the doped conductive layer 150 are shown, including the ECV doping curves of the doped conductive layer 150 in the first heavily doped region 151 and the ECV doping curves of the doped conductive layer 150 excluding the first heavily doped region 151. This application does not limit the specific doping concentration or depth of the doped conductive layer 150, as long as it meets the following requirements... Figure 4 The ECV doping curve of the medium-doped conductive layer 150 is sufficient.

[0047] The material of the doped conductive layer 150 can be at least one of polycrystalline semiconductor, amorphous semiconductor, or microcrystalline semiconductor. Preferably, the material of the doped conductive layer includes at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The thickness of the doped conductive layer 150 ranges from 40 nm to 150 nm, and optionally, the thickness ranges from 60 nm to 90 nm. This thickness range ensures that the optical loss of the doped conductive layer 150 is small and the interface passivation effect of the tunneling dielectric layer 140 is good, thereby improving the battery efficiency. For example, in this application, the material of the doped conductive layer 150 is polycrystalline silicon, and the thickness of the doped conductive layer 150 is 80 nm.

[0048] The relationship between the doping concentration and depth of the doped conductive layer 150 in the first doped region 151 conforms to... Figure 4 The ECV doping curve of the doped conductive layer 150 in the first heavily doped region 151 is shown. This application does not limit the specific doping concentration or depth of the doped conductive layer 150 in the first heavily doped region 151, as long as it meets the following requirements: Figure 4The ECV doping curve of the doped conductive layer in the first doped region 151 can be obtained. Similarly, the relationship between the doping concentration and depth of the doped conductive layer 150 other than the first doped region 151 conforms to... Figure 4 ECV doping curves of the conductive layer 150 excluding the first doped region 151.

[0049] Continue to refer to Figures 1 to 3 In some embodiments, the ratio of the total surface area of ​​the first heavily doped region 151 to the surface area of ​​the doped conductive layer 150 ranges from 1% to 20%. Optionally, the ratio of the total projected area of ​​all the first heavily doped regions 151 on the substrate 100 to the projected area of ​​the doped conductive layer 150 on the substrate 100 ranges from 1% to 20%, specifically 5%, 3%, 10%, 15%, or 20%. This ratio range can avoid the situation where the area of ​​the first heavily doped region 151 is too large, resulting in excessive optical absorption of the solar cell, which is beneficial to improving the photoelectric conversion efficiency of the solar cell. At the same time, it can avoid the situation where the area of ​​the first heavily doped region 151 is too small, resulting in a large sheet resistance of the doped conductive layer of the first heavily doped region 151 and a small contact area with the electrode 170, which is beneficial to reducing the contact resistance between the doped conductive layer 150 and the electrode 170, thereby improving the current conductivity and the photoelectric conversion efficiency of the solar cell.

[0050] In some embodiments, the top surface of the doped conductive layer 150 of the first heavily doped region 151, away from the substrate 100, is flush with the top surface of the doped conductive layers 150 other than the first heavily doped region 151. In other embodiments, the top surface of the doped conductive layer 150 of the first heavily doped region 151, away from the substrate 100, is lower than the top surface of the doped conductive layers 150 other than the first heavily doped region 151, and the height difference may be less than 20% of the thickness of the doped conductive layers 150 other than the first heavily doped region 151.

[0051] In some embodiments, along the arrangement direction of the plurality of first heavily doped regions 151, the width of the first heavily doped region 151 is 20 μm to 100 μm, specifically 20 μm, 40 μm, 58 μm, 82 μm, or 100 μm. Along the arrangement direction of the plurality of first heavily doped regions 151, the spacing between adjacent first heavily doped regions 151 ranges from 0.8 mm to 4 mm, specifically 0.8 mm, 1.5 mm, 2.8 mm, 3.6 mm, or 4 mm. The width of the first heavily doped region 151 and the spacing between adjacent first heavily doped regions 151 can further limit the ratio of the total projected area of ​​all first heavily doped regions 151 on the substrate 100 to the projected area of ​​the doped conductive layer 150 on the substrate 100 to be in the range of 1% to 20%.

[0052] In some embodiments, the first heavily doped regions 151 located below different electrodes 170 are equally spaced, so that the current collection of each first heavily doped region 151 is more uniform. Optionally, the first heavily doped regions 151 located below the same electrode 170 are equally spaced, so that the current collection of each first heavily doped region 151 is more uniform.

[0053] In some embodiments, the doping concentration of the first heavily doped region 151 is 2E+20cm. -3 ~1E+22cm -3 The dopant concentration of the conductive layer 150, excluding the first doped region 151, is 1E+20cm. -3 ~2E+20cm -3 The dopant concentration of the first doped region 151 is 2E+20cm. -3 ~2E+21cm -3 .

[0054] It is understood that doping involves incorporating a certain quantity and type of impurities or elements into a crystal, including electrically active and non-electrically active elements. It is generally expressed vaguely as "doping concentration". In the embodiments of this application, the doping ion concentration refers to the concentration of electrically active impurities (ionization state), so the doping concentration is greater than the doping ion concentration.

[0055] Continue to refer to Figure 2 In some embodiments, in a direction perpendicular to the surface 102 of the substrate 100, the depth of the first heavily doped region 151 is less than or equal to the thickness of the doped conductive layer 150 outside the first heavily doped region 151.

[0056] In some embodiments, the ratio of the depth of the first heavily doped region 151 to the thickness of the doped conductive layer 150 ranges from 50% to 100%. Preferably, the ratio of the depth of the first heavily doped region 151 to the thickness of the doped conductive layer 150 ranges from 80% to 100%, specifically 80%, 88%, 92%, or 100%.

[0057] It should be noted that the aforementioned ( Figure 2 Taking the thickness of the first heavily doped region 151 not penetrating the doped conductive layer 150 as an example, embodiments of this application may also form a first heavily doped region 151 that penetrates the thickness of the doped conductive layer 150, that is, the ratio of the depth of the first heavily doped region 151 to the thickness of the doped conductive layer 150 is 100%. Specifically, the following will be combined with Figure 3 Please provide a detailed explanation:

[0058] refer to Figure 3The substrate 100 has a second doped region 103, the doping concentration in the second doped region 103 is greater than the doping concentration in the substrate 100 excluding the second doped region 103, and the first doped region 151 is aligned with the second doped region 103 and the doping elements are of the same type.

[0059] The substrate 100 has a second doped region 103, and the surface of the second doped region 103 is exposed. The doping concentration in the second doped region 103 is greater than the doping concentration in the substrate 100 excluding the second doped region 103. This is beneficial to improving the carrier transport efficiency, the open-circuit voltage and the current transmission efficiency, and thus the photoelectric conversion efficiency of the solar cell.

[0060] In some embodiments, the depth of the second heavily doped region 103 in the direction perpendicular to the second surface 102 of the substrate 100 ranges from 0.001 μm to 1 μm, specifically 0.005 μm, 0.02 μm, 0.09 μm, 0.4 μm, or 0.9 μm. This depth range of the second heavily doped region 103 can prevent tunneling effects caused by high doping in the second heavily doped region 103, meaning the dopant elements in the second heavily doped region 103 will not diffuse to the surface of the substrate 100 in contact with the emitter 110 or into the emitter 110, thereby increasing the open-circuit voltage of the solar cell and improving its photoelectric conversion efficiency.

[0061] In some embodiments, along the arrangement direction of the plurality of first doped regions 151, the width of the first doped region 151 is smaller than the width of the second doped region 103. The doping concentration in the second doped region 103 is equal to the doping concentration in the first doped region 151; the doping concentration in the second doped region 103 is 1E+20cm. -3 ~1E+22cm -3 The dopant ion concentration in the second doped region 103 is 1E+20cm⁻¹. -3 ~2E+20cm -3 In other embodiments, the doping concentration in the second doped region 103 is less than the doping concentration in the first doped region 151.

[0062] In some embodiments, the tunneling dielectric layer 140 has a third doped region 141 extending through the thickness of the tunneling dielectric layer 140. The third doped region 141 contacts the first doped region 151 and the second doped region 103, respectively. The first doped region 151, the second doped region 103, and the third doped region 141 are aligned and have the same type of dopant element. This reduces recombination losses between the tunneling dielectric layer 140 and the substrate 100, and between the tunneling dielectric layer 140 and the doped conductive layer 150, which is beneficial for improving carrier transport efficiency, open-circuit voltage, and current transmission efficiency, thereby improving the photoelectric conversion efficiency of the solar cell. Preferably, one end of the third doped region 141 contacts the first doped region 151, and the other end of the third doped region 141 contacts the second doped region 103.

[0063] In some embodiments, along the arrangement direction of the plurality of first heavily doped regions 151, the width of the second heavily doped region 103 is smaller than the width of the third heavily doped region 141; the width of the first heavily doped region 151 is equal to the width of the third heavily doped region 141. In other embodiments, the width of the second heavily doped region 103 is equal to the width of the third heavily doped region 141; the width of the first heavily doped region 151 is smaller than the width of the third heavily doped region 141. In still other embodiments, the widths of the first heavily doped region 151, the third heavily doped region 141, and the second heavily doped region 103 gradually increase. In one example, the width of the first heavily doped region 151 is 50 μm, the width of the third heavily doped region 141 is 60 μm, and the width of the second heavily doped region 103 is 70 μm.

[0064] In some embodiments, the doping concentration within the third doped region 141 is 6E+19cm- 3 ~2E+20cm -3 The dopant concentration in the third doped region 141 is 6E+19cm⁻¹. -3 ~1E+20cm -3 The doping concentrations in the third doped region 141, the second doped region 103, and the first doped region 151 can be the same. In other embodiments, the doping concentrations in the first doped region 151, the third doped region 141, and the second doped region 103 decrease in a stepwise manner; for example, the doping concentration in the first doped region 151 is 4E+20cm. -3 The doping concentration in the third doped region 141 is 3E+20cm. -3 The doping concentration in the second doped region 103 is 2E+20cm. -3 .

[0065] It is understandable that the doping concentration of the first heavily doped region 151 can be the same throughout the first heavily doped region 151, or the first heavily doped region 151 can have a step-like or gradient distribution towards the second heavily doped region 103, with the doping concentration increasing closer to the electrode. Similarly, the doping concentration of the second heavily doped region 103 can be the same throughout the second heavily doped region 103, or the first heavily doped region 151 can have a step-like or gradient distribution towards the second heavily doped region 103, with the doping concentration increasing closer to the first heavily doped region 151. Likewise, the doping concentration of the third heavily doped region 141 can be the same throughout the third heavily doped region 141, or the first heavily doped region 151 can have a step-like or gradient distribution towards the second heavily doped region 103, with the doping concentration increasing closer to the first heavily doped region 151.

[0066] It should be noted that, Figure 2 The doping concentration of the doped conductive layer 150 in the first heavily doped region 151 of the solar cell shown is... Figure 3 The doping concentration of the doped conductive layer 150 in the first heavily doped region 151 of the solar cell shown can be the same or different, but the doping concentration range of the doped conductive layer 150 in the first heavily doped region 151 of the solar cell is 2E+20cm. -3 ~1E+22cm -3 .

[0067] Similarly, the width, length and spacing between adjacent first doped regions 151 can be set according to different structural requirements, but the ratio of the total surface area of ​​the first doped region 151 to the surface area of ​​the doped conductive layer 150 must be in the range of 1% to 20%.

[0068] Continue to refer to Figures 1 to 3 The passivation layer 160 can reduce recombination in the metal region generated by the contact between the electrode 170 and the substrate 100, thereby improving battery efficiency. The passivation layer 160 can be a single-layer structure or a stacked structure, and the material of the passivation layer 160 can be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0069] Electrode 170 is a grid line of a solar cell, used to collect and summarize the current from the solar cell. Electrode 170 may be formed by sintering a burn-through paste. The contact between electrode 170 and the doped conductive layer 150 may be localized or complete. The material of electrode 170 may be one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In some embodiments, when the doped conductive layer 150 is located on the back surface of the substrate 100, electrode 170 is a lower electrode or a back electrode. In some cases, electrode 170 refers to fine grid lines or finger grid lines to distinguish it from main grid lines or busbars.

[0070] The first direction and the second direction can intersect so that at least two first heavily doped regions 151 are in contact with the same electrode 170. The angle between the first direction and the second direction can be 0° to 90°. Preferably, the angle between the first direction and the second direction can be 90°, that is, the extension direction of the first heavily doped region 151 is perpendicular to the extension direction of the electrode 170.

[0071] In some embodiments, continue to refer to Figure 1 The solar cell further includes: a first passivation layer 120, which is located on the surface of the emitter 110 away from the substrate 100, and is regarded as a front passivation layer; and a plurality of spaced electrodes 130, which extend along a second direction and penetrate the first passivation layer 120 and are in contact with the emitter 110.

[0072] In some embodiments, the first passivation layer 120 may be a single-layer structure or a stacked structure, and the material of the first passivation layer 120 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0073] Electrode 130 may be sintered from a burn-through slurry. The contact between electrode 130 and emitter 110 may be localized or complete. The material of electrode 130 may be one or more of aluminum, silver, nickel, gold, molybdenum, or copper. In some embodiments, electrode 130 is an upper electrode or a front electrode. In some cases, electrode 130 refers to fine grid lines or finger grid lines, to distinguish it from main grid lines or busbars.

[0074] In the solar cell technical solution provided in this application embodiment, the doped conductive layer 150 has a plurality of first heavily doped regions 151 arranged at intervals. The dopant ion concentration in the first heavily doped region 151 is greater than the dopant ion concentration in the doped conductive layer 150 excluding the first heavily doped region 151. A plurality of electrodes 170 are arranged at intervals, with at least two first heavily doped regions 151 in contact with the same electrode 170. Thus, the doped conductive layer 150 can be divided into the first heavily doped region 151 and regions excluding the first heavily doped region 151. That is, the doping concentration and doping depth of the first heavily doped region 151 can be appropriately set without affecting the doping concentration and thickness of the doped conductive layer 150 excluding the first heavily doped region 151. This is beneficial for reducing the sheet resistance and optical absorption of the doped conductive layer 150, and can improve the photoelectric conversion efficiency of the solar cell. The doped conductive layer 150 has multiple spaced-apart first heavily doped regions 151. The dopant concentration in the first heavily doped regions 151 is greater than the dopant concentration in the doped conductive layer 150 excluding the first heavily doped regions 151. The number of majority carriers in the first heavily doped regions 151 is greater than that in other regions, which increases the current transmission capability, thereby reducing the series resistance of the solar cell and improving the photoelectric conversion efficiency. At least two first heavily doped regions 151 are in contact with the same electrode 170. The first heavily doped region 151 with a higher doping concentration forms a good ohmic contact with the electrode 170. The contact resistance between the first heavily doped region 151 with a higher doping concentration and the electrode 170 is lower than the contact resistance between the doped conductive layer 150 excluding the first heavily doped regions 151 and the electrode 170, resulting in better current conduction and improving the photoelectric conversion efficiency.

[0075] Figure 5 This is a schematic diagram of a solar cell provided in another embodiment of this application. Figure 5 The solar cells shown are Figures 1-3 The solar cells shown have the same structural composition, the main difference being that the tunneling dielectric layer and the doped conductive layer are located on the first surface (also known as the front surface) of the substrate. Figures 1-3 Details of contents or elements that are the same or similar to those described in the embodiments shown will not be repeated; only descriptions that differ from the above descriptions will be described in detail. The following will combine... Figure 5 A solar cell provided in another embodiment of this application will be described in detail.

[0076] refer to Figure 5The solar cell includes: a substrate 200 having a first surface 201 (also referred to as the front surface 201) and a second surface 202 (also referred to as the rear surface 202) opposite to each other; a tunneling dielectric layer 240 and a doped conductive layer 250 located on the side of the first surface 201 of the substrate 200, the tunneling dielectric layer 240 being located between the doped conductive layer 250 and the substrate 200; and a passivation layer 260 located on the surface of the doped conductive layer 250 away from the substrate 200, for passivation. Layer 260 is considered as a front passivation layer; a plurality of spaced electrodes 270 (also referred to as first electrodes 270) extend along a second direction, and each electrode 270 penetrates the passivation layer 260 and contacts the doped conductive layer 250; a second passivation layer 207 and an electrode 208 (also referred to as second electrode 208) are located on the side of the second surface 202 of the substrate 200, the electrode 208 penetrates the second passivation layer 207 and contacts the substrate 200, and the second passivation layer 207 is considered as a rear passivation layer.

[0077] Understandable Figure 5 The solar cell shown can be a back-junction solar cell, meaning the PN junction of the cell forms the back side of the cell. The doping element in the doped conductive layer 250 is of the same type as the doping element in the substrate 200. For example, if the substrate 200 is an N-type substrate, the doped conductive layer 250 is doped with N-type elements; or, for example, if the substrate 200 is a P-type substrate, the doped conductive layer 250 is doped with P-type elements. An emitter region with the opposite doping element type to that of the substrate 200 is formed inside the substrate 200 near the second surface 202.

[0078] It is understood that the doped conductive layer 250 and the doped conductive layer 150 (reference) Figures 1 to 3 The elements are the same or similar; that is, in some embodiments of this application, the doped conductive layer 250 may have a plurality of first heavily doped regions arranged at intervals. Similarly, the substrate 200 may have a second heavily doped region. The tunneling dielectric layer 240 may have a third heavily doped region.

[0079] In some embodiments, the second passivation layer 207 may be a single-layer structure or a stacked structure, and the material of the second passivation layer 207 may be one or more of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0080] Electrode 208 can be sintered from burn-through slurry. The contact between electrode 208 and substrate 200 can be localized or complete. The material of electrode 208 can be one or more of aluminum, silver, nickel, gold, molybdenum, or copper.

[0081] In some embodiments, electrode 270 is an upper electrode or a front electrode, and electrode 208 is a lower electrode or a back electrode.

[0082] for Figure 5 In the described solar cell, the tunneling dielectric layer 240 and the doped conductive layer 250 are located on the first surface 201 of the substrate 200. The doped conductive layer 250 has a first heavily doped region, which can reduce the sheet resistance and optical absorption of the doped conductive layer 250, thereby improving the photoelectric conversion efficiency of the solar cell. Simultaneously, the two first heavily doped regions are in contact with the same electrode 270, forming a good ohmic contact and improving current conduction, which is beneficial for improving photoelectric conversion efficiency. Furthermore, the location of the tunneling dielectric layer 240 and the doped conductive layer 250 on the first surface 201 of the substrate 200 can reduce the probability of carrier and hole recombination on the first surface 201 of the substrate 200, and also reduce metal recombination in direct contact between the electrode 270 and the substrate 200, which is beneficial for improving photoelectric conversion efficiency.

[0083] The aforementioned (such as) Figure 1 or Figure 5 The solar cell shown is an example in which a tunneling dielectric layer and a heavily doped conductive layer with a doped region are disposed on a single surface (first surface or second surface) of the substrate. Other embodiments in this application also provide a tunneling dielectric layer and a doped conductive layer disposed on both surfaces (first surface and second surface) of the substrate, i.e., the solar cell is a double-sided tunneling oxide passivated contact cell. Figures 1-5 Details of contents or elements that are the same or similar to those described in the embodiments will not be repeated; only descriptions that differ from the above descriptions will be described in detail. The following will combine... Figure 6 as well as Figure 7 Please provide a detailed explanation:

[0084] Figure 6 This is a schematic diagram of a solar cell provided in yet another embodiment of this application. (Reference) Figure 6The solar cell includes: a substrate 300 having a first surface 301 and a second surface 302 opposite to each other; a tunneling dielectric layer 340 (also referred to as a first tunneling layer 340) and a doped conductive layer 350 (also referred to as a first conductive layer 350) located on the first surface 301 side of the substrate 300, the tunneling dielectric layer 340 being located between the doped conductive layer 350 and the substrate 300; a passivation layer 360 located on the surface of the doped conductive layer 350 away from the substrate 300, the passivation layer 360 being considered as a front passivation layer; and a plurality of spaced-apart... The electrode 370 extends along the second direction, and each electrode 370 penetrates the passivation layer 360 and contacts the doped conductive layer 350. The electrode 370 is the upper electrode or the front electrode. The first tunneling dielectric layer 381, the first doped conductive layer 382, ​​the third passivation layer 383 and the electrode 384 are stacked sequentially on the second surface 302 side of the substrate 300. The electrode 384 penetrates the third passivation layer 383 and contacts the first doped conductive layer 382. The third passivation layer 383 is regarded as the rear passivation layer. The electrode 384 is the lower electrode or the back electrode.

[0085] In some embodiments, the dopant type of the doped conductive layer 350 is the same as the dopant type in the substrate 300, and the dopant type of the first doped conductive layer 382 is opposite to that in the substrate 300. In one example, the substrate 300 has N-type dopant, the doped conductive layer 350 has N-type dopant, and the first doped conductive layer 382 has P-type dopant. In another example, the substrate 300 has P-type dopant, the doped conductive layer 350 has P-type dopant, and the first doped conductive layer 382 has N-type dopant.

[0086] Understandable Figure 6 The solar cell shown can be a back junction solar cell.

[0087] The doped conductive layer 350 and Figure 1-3 The doped conductive layer 150 can be any identical or similar element, and the doped conductive layer 350 can have multiple first heavily doped regions arranged at intervals. Similarly, the substrate 300 can have second heavily doped regions. The tunneling dielectric layer 340 can have third heavily doped regions.

[0088] In some embodiments, the material of the first tunneling dielectric layer 381 can be any one of silicon oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, and intrinsic polycrystalline silicon. The thickness of the first tunneling dielectric layer 381 can be 0.5 nm to 2 nm, optionally, the thickness of the first tunneling dielectric layer 381 is 0.5 nm to 1.5 nm, and further, the thickness of the first tunneling dielectric layer 381 is 0.5 nm to 1.2 nm. The material of the first doped conductive layer 382 includes at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The thickness of the first doped conductive layer 382 ranges from 40 nm to 150 nm, optionally, the thickness of the first doped conductive layer 382 ranges from 60 nm to 90 nm.

[0089] In some embodiments, the third passivation layer 383 may be a single-layer structure or a stacked structure, and the material of the third passivation layer 383 may be one or more of the following materials: silicon nitride, silicon oxynitride, silicon carbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

[0090] Electrode 384 can be sintered from a burn-through paste. The contact between electrode 384 and the first doped conductive layer 381 can be localized or complete. The material of electrode 384 can be one or more of aluminum, silver, nickel, gold, molybdenum, or copper.

[0091] for Figure 6 In the solar cell described above, the tunneling dielectric layer 340 and the doped conductive layer 350 are located on the first surface 301 of the substrate 300. This reduces the probability of carrier and hole recombination on the first surface 301 of the substrate 300 and also reduces metal recombination in direct contact between the electrode 370 and the substrate 300, which is beneficial to improving photoelectric conversion efficiency. The doped conductive layer 350 has a first heavily doped region, which reduces the sheet resistance and optical absorption of the doped conductive layer 350, thereby improving the photoelectric conversion efficiency of the solar cell. At the same time, the two first heavily doped regions are in contact with the same electrode 370, which can form a good ohmic contact, resulting in better current conduction and further improving photoelectric conversion efficiency. Furthermore, a first tunneling dielectric layer 381, a first doped conductive layer 382, ​​a third passivation layer 383, and an electrode 384 are sequentially stacked on the second surface 302 side of the substrate 300. The electrode 384 penetrates the third passivation layer 383 and is in contact with the first doped conductive layer 382. That is, the solar cell is a double-sided tunneling oxide passivated contact cell. Both the first surface 301 and the second surface 302 of the substrate 300 are light-receiving surfaces, which increases the surface area for collecting photogenerated carriers and is beneficial to improving the photoelectric conversion efficiency of the solar cell.

[0092] Figure 7 This is a schematic diagram of a solar cell provided in another embodiment of this application. Figure 7 The provided solar cell is similar to the aforementioned embodiment ( Figure 6The solar cell provided has the same structural composition as the one described in the above embodiments. Details of the contents or components that are the same or similar to those described in the above embodiments will not be repeated. Only descriptions that are different from the above descriptions will be described in detail.

[0093] refer to Figure 7 The solar cell includes: a substrate 400 having a first surface 401 and a second surface 402 opposite to each other; a first tunneling dielectric layer 481, a first doped conductive layer 482, a third passivation layer 483, and an electrode 484 sequentially stacked on the first surface 401 side of the substrate 400, the electrode 484 penetrating the third passivation layer 483 and contacting the first doped conductive layer 482, the third passivation layer 483 being considered the front passivation layer, and the electrode 484 being the top electrode or the front electrode; and a tunneling dielectric layer 481 on the second surface 402 side of the substrate 400. 40 (also known as the second tunneling layer 440) and a doped conductive layer 450 (also known as the second conductive layer 450), the tunneling dielectric layer 440 being located between the doped conductive layer 450 and the substrate 400; a passivation layer 460, the passivation layer 460 being located on the surface of the doped conductive layer 450 away from the substrate 400, the passivation layer 460 being considered as a back passivation layer; a plurality of spaced electrodes 470, the electrodes 470 extending along the second direction, and each electrode 470 penetrating the passivation layer 460 and contacting the doped conductive layer 450, the electrodes 470 being the lower electrode or the back electrode.

[0094] The doped conductive layer 450 and Figure 1-3 The doped conductive layer 150 can be any identical or similar element, and the doped conductive layer 450 can have multiple first heavily doped regions arranged at intervals. Similarly, the substrate 400 can have second heavily doped regions. The tunneling dielectric layer 440 can have third heavily doped regions.

[0095] In some embodiments, the dopant type of the doped conductive layer 450 is the same as the dopant type in the substrate 400, and the dopant type of the first doped conductive layer 482 is opposite to that in the substrate 400. In one example, the substrate 400 has N-type dopant, the doped conductive layer 450 has N-type dopant, and the first doped conductive layer 482 has P-type dopant. In another example, the substrate 400 has P-type dopant, the doped conductive layer 450 has P-type dopant, and the first doped conductive layer 482 has N-type dopant.

[0096] Understandable Figure 7 The solar cell shown can be a positive junction solar cell.

[0097] Accordingly, another aspect of this application embodiment also provides a photovoltaic module, which is used to convert received light energy into electrical energy. The photovoltaic module includes: a battery string, consisting of multiple of the above-described... Figures 1 to 7It consists of any one of the solar cells connected together; an encapsulating film used to cover the surface of the cell string; and a cover plate used to cover the surface of the encapsulating film facing away from the cell string.

[0098] The encapsulating film can be an organic encapsulating film such as EVA or POE, which covers the surface of the battery string to seal it. The cover plate can be a glass cover plate or a plastic cover plate, which covers the surface of the encapsulation layer away from the battery string. In some embodiments, a light-trapping structure is provided on the cover plate to increase the utilization rate of incident light. Photovoltaic modules have high current collection capability and low carrier recombination rate, which can achieve high photoelectric conversion efficiency.

[0099] Accordingly, another aspect of this application provides a method for preparing a solar cell, used to prepare the above-described embodiments ( Figures 1 to 7 The solar cell provided is described above. Details of contents or elements that are the same as or similar to those described in the above embodiments will not be repeated; only descriptions that differ from the above descriptions will be described in detail. Exemplarily, embodiments of this application provide a method for fabricating a solar cell that can produce a solar cell as described above. Figures 1 to 3 The solar cell shown.

[0100] refer to Figure 4 , Figures 8 to 16 , Figures 8 to 16 This is a schematic diagram of the structure corresponding to each step in the fabrication method of a solar cell provided in an embodiment of this application. Wherein, Figures 11 to 14 This is a partial structural diagram, showing only the structure of the second surface side of the substrate in the solar cell.

[0101] refer to Figure 8 A substrate 100 is provided, the substrate 100 having a first surface 101 and a second surface 102 disposed opposite to each other.

[0102] refer to Figure 9 An emitter 110 is formed, which is located on the first surface 101 side of the substrate 100.

[0103] refer to Figures 10 to 13 A tunneling dielectric layer 140 and a doped conductive layer 150 are formed. The doped conductive layer 150 is located on the second surface 102 side of the substrate 100. The tunneling dielectric layer 140 is located between the doped conductive layer 150 and the substrate 100. The doped conductive layer 150 contains a doping element, which is of the N-type or P-type type. The doped conductive layer 150 has a plurality of first heavily doped regions 151 arranged at intervals. The first heavily doped regions 151 extend along a first direction, and the doped conductive layer 150 exposes the surface of the first heavily doped regions 151 away from the substrate 100. The doping concentration in the first heavily doped regions 151 is greater than the doping concentration in the doped conductive layer 150 excluding the first heavily doped regions 151.

[0104] In some embodiments, the tunneling medium layer 140 is formed by one or more of low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD).

[0105] The following will combine Figures 11 to 14 The steps for forming the doped conductive layer 150 are described in detail.

[0106] refer to Figure 11 An initial doped conductive layer 104 is formed, which is located on the side of the tunneling dielectric layer 140 away from the substrate 100, and the initial doped conductive layer 150 contains doped elements.

[0107] In some embodiments, an intrinsically doped conductive layer can be formed by LPCVD followed by diffusion or ion implantation to form an initial doped conductive layer 104. The intrinsically doped conductive layer can be an intrinsic polycrystalline silicon layer. In other embodiments, an initial doped conductive film is deposited by PECVD, followed by annealing to form the initial doped conductive layer 104. The material of the initial conductive film can be amorphous silicon or microcrystalline silicon. The material of the initial doped conductive layer 104 can be polycrystalline silicon, amorphous silicon, or microcrystalline silicon. Exemplarily, in this application, the material of the initial doped conductive layer 104 is polycrystalline silicon.

[0108] In some embodiments, the relationship between the doping concentration and depth of the initial doped conductive layer 104 conforms to... Figure 4 The ECV doping curves of the intermediate-doped conductive layer include the ECV doping curves of the first heavily doped region and the ECV doping curves of the conductive layers excluding the first heavily doped region. This application does not limit the specific doping concentration or depth of the initial doped conductive layer 104, as long as it meets the following requirements... Figure 4 The ECV doping curve of the medium-doped conductive layer is sufficient.

[0109] In some embodiments, the doping element type in the initial doped conductive layer 104 may be the same as the doping element type in the substrate 100. For example, the doping element type in the substrate 100 may be N-type, and the doping element type in the initial doped conductive layer 104 may also be N-type.

[0110] In some embodiments, the thickness of the initial doped conductive layer 104 ranges from 40 nm to 150 nm. Optionally, the thickness of the initial doped conductive layer 104 ranges from 60 nm to 90 nm. This thickness range ensures that the optical loss of the subsequently formed doped conductive layer is small and the interface passivation effect of the tunneling dielectric layer 140 is good, thereby improving the battery efficiency. The thickness of the initial doped conductive layer 104 may include, but is not limited to, 40 nm to 150 nm, or other thicknesses known to those skilled in the art.

[0111] refer to Figure 11 and Figure 12 A portion of the initial doped conductive layer 104 is doped to increase the concentration of doping elements in that portion of the layer, thereby forming a first heavily doped region 151. The remaining portion of the initial doped conductive layer 104 is then used as a doped conductive layer 150.

[0112] It is understood that doping in doping treatment refers to incorporating a certain number and type of impurities or elements into a crystal, including electrically active impurities and non-electrically active impurities. It is generally expressed in a vague way as "doping concentration". In the embodiments of this application, the doping ion concentration refers to the concentration of electrically active impurities (ionization state). Therefore, the doping concentration is greater than the doping ion concentration.

[0113] Specifically, refer to Figure 11 A doped source layer 105 is formed on the surface of the initial doped conductive layer 104, and the doped source layer 105 contains doped elements.

[0114] In some embodiments, the doped source layer 105 is located over the entire surface of the initial doped conductive layer 104. The material of the doped source layer 105 may include, but is not limited to, phosphosilicate glass (PSG) or borophosphosilicate glass (BPSG).

[0115] refer to Figure 12 A diffusion process is performed to make some regions of the doped source layer 105 (reference) Figure 10 The doped ions diffuse into the initial doped conductive layer 104 to form the first heavily doped region 151; the doped source layer 105 is removed.

[0116] In some embodiments, a localized laser diffusion process is used for diffusion treatment. Wet etching completely removes the doped source layer 105, preventing residual phosphosilicate glass from causing moisture absorption on the silicon wafer surface, which would lead to reduced current and power attenuation. It also prevents the passivation layer subsequently formed on the doped conductive layer 150 from detaching, thus improving the photoelectric conversion efficiency of the solar cell. The wet etching solution is a mixture of HNO3 and HF. In other embodiments, thermal diffusion or ion implantation processes can be used for diffusion treatment.

[0117] It should be noted that the aforementioned ( Figure 11-12 Taking the example where the doped source layer 105 is located on the entire surface of the initial doped conductive layer 104, the embodiments of this application can also form multiple sub-doped source layers spaced apart. Specifically, the following will be combined with Figure 13 Please provide a detailed explanation:

[0118] refer to Figure 13 A plurality of sub-doped source layers 106 are formed at intervals on the surface of the initial semiconductor layer 150, and each sub-doped source layer 106 extends along a first direction.

[0119] In some embodiments, the ratio of the total surface area of ​​the sub-doped source layers 106 to the area of ​​the initial doped conductive layer 104 ranges from 1% to 20%. Specifically, the ratio of the total projected area of ​​all sub-doped source layers 106 on the substrate 100 to the projected area of ​​the initial doped conductive layer 106 on the substrate 100 ranges from 1% to 20%, specifically 5%, 3%, 10%, 15%, or 20%. This ratio range can prevent the situation where the area of ​​the subsequently formed first doped region is too large, resulting in excessive optical absorption of the solar cell, which is beneficial to improving the photoelectric conversion efficiency of the solar cell. At the same time, it can prevent the situation where the area of ​​the first doped region is too small, resulting in a large sheet resistance of the initial doped conductive layer 104 in the first doped region and a small contact area with the subsequently formed electrode, which is beneficial to reducing the contact resistance between the doped conductive layer and the subsequently formed electrode, thereby improving the current conduction and the photoelectric conversion efficiency of the solar cell.

[0120] In some embodiments, the sub-doped source layers 106 located below different subsequently formed electrodes are equally spaced, so that the current collection of each subsequently formed first heavily doped region is more uniform. Preferably, the sub-doped source layers 106 located below the same subsequently formed electrode are equally spaced, so that the current collection of each first heavily doped region is more uniform.

[0121] In some embodiments, along the arrangement direction of the plurality of sub-doped source layers 106, the width of the sub-doped source layer 106 is 20 μm to 100 μm, specifically 20 μm, 40 μm, 58 μm, 82 μm, or 100 μm. Along the arrangement direction of the plurality of sub-doped source layers 106, the spacing between adjacent sub-doped source layers 106 ranges from 0.8 mm to 4 mm, specifically 0.8 mm, 1.5 mm, 2.8 mm, 3.6 mm, or 4 mm. The width of the sub-doped source layer 106 and the spacing between adjacent sub-doped source layers 106 can further ensure that the ratio of the total surface area of ​​the subsequently formed first heavily doped region to the surface area of ​​the doped conductive layer ranges from 1% to 20%.

[0122] In some embodiments, the material of the sub-doped source layer 106 may include, but is not limited to, phosphosilicate glass or borosilicate glass.

[0123] Continue to refer to Figure 11 Diffusion processing is performed to make the sub-doped source layer 106 (reference) Figure 13 The doping elements in the first doped conductive layer 104 diffuse into the first doped conductive layer 104 to form the first heavily doped region 151; the sub-doped source layer 106 is removed.

[0124] It is understood that the doping process will eliminate some of the top surface of the initial doped conductive layer 104 away from the substrate 100. That is, the top surface of the doped conductive layer 150 of the first heavily doped region 151 away from the substrate 100 is lower than the top surface of the doped conductive layers 150 other than the first heavily doped region 151, and the height difference can be less than 20% of the thickness of the doped conductive layers 150 other than the first heavily doped region 151. Optionally, the top surface of the first heavily doped region 151 away from the substrate 100 is flush with the top surface of the doped conductive layers 150 other than the first heavily doped region 151.

[0125] In other embodiments, reference is made to... Figure 14 A diffusion process is performed to make some regions of the doped source layer 105 (reference) Figure 11 The doping elements in the doped source layer 105 diffuse into the initial doped conductive layer 104 to form a first heavily doped region 151. The doping elements in the doped source layer 105 also diffuse into the tunneling dielectric layer 140 and a portion of the thickness of the substrate 100 to form a second heavily doped region 103 in the substrate 100 opposite to the first heavily doped region 151, and a third heavily doped region 141 in the tunneling dielectric layer 140 opposite to the first heavily doped region 151. The doped source layer 105 is then removed.

[0126] In some embodiments, the first heavily doped region 151 extends through the thickness of the doped conductive layer 150, that is, the ratio of the depth of the first heavily doped region 151 to the thickness of the doped conductive layer 150 is 100%.

[0127] It should be noted that, Figure 12 The doping concentration of the first heavily doped region 151 of the solar cell shown is... Figure 14 The doping concentration of the first heavily doped region 151 of the solar cell shown can be the same or different, but the doping range of the first heavily doped region 151 of the solar cell is 2E+20cm. -3 ~1E+22cm -3 .

[0128] Similarly, the width, length and spacing between adjacent first doped regions 151 can be set according to different structural requirements, but the ratio of the total surface area of ​​the first doped region 151 to the surface area of ​​the doped conductive layer 150 must be in the range of 1% to 20%.

[0129] It can be formed using a nanosecond laser with a wavelength of 532nm or other lasers that can be doped. Figure 12 and Figure 14 Solar cells, and forming Figure 12 and Figure 14 The process parameters for diffusion treatment of solar cells can vary. In some embodiments, the formation of... Figure 12 The process parameters for the solar cells shown include: laser power of 5W to 40W, laser frequency of 50kHz to 250kHz; formation... Figure 14 The process parameters of the solar cell shown include: laser power of 40W to 100W and laser frequency of 250KHz to 450KHz.

[0130] refer to Figure 15 A passivation layer 160 is formed, which is located on the surface of the doped conductive layer 150 away from the substrate 100.

[0131] Continue to refer to Figure 15 A first passivation layer 120 is formed, which is located on the surface of the emitter 110 away from the substrate 100.

[0132] refer to Figure 16 Multiple electrodes 170 are formed at intervals, the electrodes 170 extend along the second direction, and each electrode 170 penetrates the passivation layer 160 and contacts the doped conductive layer 150, and at least two first heavily doped regions 151 are in contact with the same electrode 170.

[0133] Continue to refer to Figure 16 Multiple electrodes 130 are formed at intervals, the electrodes 130 extend along the second direction, and each electrode 130 penetrates the first passivation layer 120 and contacts the emitter 110.

[0134] In other embodiments, the method for fabricating solar cells can form as follows: Figure 5The solar cell shown includes: a substrate 200 having opposing first surfaces 201 and second surfaces 201; a tunneling dielectric layer 240, a doped conductive layer 250, a passivation layer 260, and a plurality of spaced electrodes 270 sequentially formed on the first surface 201 side, the electrodes 270 penetrating the passivation layer 260 and contacting the doped conductive layer 250; and a second passivation layer 207 and an electrode 208 sequentially formed on the second surface 202 side, the electrode 208 penetrating the second passivation layer 207 and contacting the substrate 200.

[0135] It is understood that the process steps for forming the second passivation layer 207 are the same as those for forming the first passivation layer 120 in the above embodiment (see reference). Figure 15 The process steps for forming electrode 208 are the same or similar to those for forming electrode 130 in the above embodiment, and will not be elaborated further here. Similarly, the process steps for forming electrode 208 are the same as those for forming electrode 130 in the above embodiment (see reference). Figure 16 The process steps are the same or similar.

[0136] In some other embodiments, the method for fabricating solar cells can form as follows: Figure 6 The solar cell shown includes: a substrate 300 having a first surface 301 and a second surface 302 opposite to each other; a tunneling dielectric layer 340, a doped conductive layer 350, a passivation layer 360 and a plurality of spaced electrodes 370 sequentially formed on the first surface 301 side, the electrodes 370 penetrating the passivation layer 360 and contacting the doped conductive layer 350; and a first tunneling dielectric layer 381, a first doped conductive layer 382, ​​a third passivation layer 383 and an electrode 384 sequentially formed on the second surface 302 side, the electrode 384 penetrating the third passivation layer 383 and contacting the first doped conductive layer 382.

[0137] It is understood that the process steps for forming the first tunneling medium layer 381 are the same as those for forming the tunneling medium layer 140 in the above embodiment (see reference). Figure 10 The process steps for forming the first doped conductive layer 382 are the same or similar to those for forming the doped conductive layer 150 in the above embodiment (see reference). Figure 10 The process steps for forming the third passivation layer 383 are the same as or similar to those for forming the passivation layer 160 in the above embodiment (see reference). Figure 15 The process steps for forming electrode 384 are the same as or similar to those for forming electrode 170 in the above embodiment (see reference). Figure 15 The process steps are the same or similar.

[0138] In some other embodiments, the method for fabricating a solar cell can form as follows: Figure 7The solar cell shown includes: a substrate 400 having a first surface 401 and a second surface 402 opposite to each other; a first tunneling dielectric layer 481, a first doped conductive layer 482, a third passivation layer 483 and an electrode 484 sequentially formed on the first surface 401 side, the electrode 484 penetrating the third passivation layer 483 and contacting the first doped conductive layer 484; and a tunneling dielectric layer 440, a doped conductive layer 450, a passivation layer 460 and a plurality of spaced electrodes 470 sequentially formed on the second surface 402 side, the electrodes 470 penetrating the passivation layer 460 and contacting the doped conductive layer 450.

[0139] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A solar cell, characterized in that, include: Base; A tunneling dielectric layer and a doped conductive layer are located on the surface of the substrate. The tunneling dielectric layer is located between the doped conductive layer and the substrate. The doped conductive layer contains a doping element, which is of type N or P. The doped conductive layer has a plurality of spaced first heavily doped regions that extend along a first direction. The doping concentration in the first heavily doped regions is greater than the doping concentration in the doped conductive layer excluding the first heavily doped regions. A passivation layer is located on the surface of the doped conductive layer away from the substrate; Multiple electrodes are spaced apart, the electrodes extend along a second direction, the electrodes penetrate the passivation layer and contact the doped conductive layer, and at least two of the first heavily doped regions contact the same electrode; The substrate has a second doped region, the doping concentration of the second doped region is greater than the doping concentration of the substrate excluding the second doped region, the first doped region and the second doped region are aligned and the doping elements are of the same type; the doping concentration of the second doped region is less than or equal to the doping concentration of the first doped region.

2. The solar cell according to claim 1, characterized in that, In a direction perpendicular to the surface of the substrate, the depth of the first heavily doped region is less than or equal to the thickness of the doped conductive layer outside the first heavily doped region.

3. The solar cell according to claim 2, characterized in that, The ratio of the depth of the first heavily doped region to the thickness of the doped conductive layer ranges from 80% to 100%.

4. The solar cell according to claim 1 or 3, characterized in that, The thickness of the doped conductive layer ranges from 40 nm to 150 nm.

5. The solar cell according to claim 1, characterized in that, The doping concentration of the first heavily doped region is 2E+20cm. -3 ~1E+22cm -3 .

6. The solar cell according to claim 1, characterized in that, In the direction perpendicular to the substrate surface, the depth of the second heavily doped region ranges from 0.001 μm to 1 μm.

7. The solar cell according to claim 1, characterized in that, The tunneling dielectric layer has a third doped region that extends through the thickness of the tunneling dielectric layer. The third doped region is in contact with the first doped region and the second doped region, respectively. The first doped region, the second doped region and the third doped region are aligned and have the same type of doping element.

8. The solar cell according to claim 7, characterized in that, Along the arrangement direction of the plurality of first heavily doped regions, the width of the first heavily doped region is smaller than the width of the second heavily doped region; the width of the first heavily doped region is less than or equal to the width of the third heavily doped region.

9. The solar cell according to claim 1, characterized in that, The ratio of the total surface area of ​​the first heavily doped region to the surface area of ​​the doped conductive layer ranges from 1% to 20%.

10. The solar cell according to claim 1, characterized in that, Along the arrangement direction of the plurality of first heavily doped regions, the width of the first heavily doped region is 20μm~100μm.

11. The solar cell according to claim 1, characterized in that, Along the arrangement direction of the plurality of first heavily doped regions, the spacing between adjacent first heavily doped regions ranges from 0.8 mm to 4 mm.

12. The solar cell according to claim 1, characterized in that, The material of the doped conductive layer includes at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

13. The solar cell according to claim 1, characterized in that, The substrate has a first surface and a second surface disposed opposite to each other, and the tunneling dielectric layer and the doped conductive layer are located on the first surface side and / or the second surface side of the substrate.

14. The solar cell according to any one of claims 1 to 3 or 5 to 13, characterized in that, The type of doped element in the substrate is the same as the type of doped element in the doped conductive layer.

15. A photovoltaic module, characterized in that, include: A battery string, consisting of multiple solar cells connected together according to any one of claims 1 to 14; An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

Images