Heterojunction solar cell, method for manufacturing the same, and photovoltaic module

Abstract

The application relates to the field of solar cells, and discloses a heterojunction solar cell, a preparation method thereof and a photovoltaic module. The preparation method comprises the following steps: printing, printing a first electrode paste on a first surface of a solar cell semi-product; wherein the material of the solar cell semi-product comprises a silicon material and a transparent conductive material, the solar cell semi-product comprises a first surface and a second surface arranged oppositely, the first electrode paste comprises a metal material and an organic carrier; incomplete drying, drying the first electrode paste to retain part of the organic carrier in the first electrode paste; first photon sintering, performing light source irradiation on the second surface of the solar cell semi-product, the light source is configured to act on the first surface to sinter the first electrode paste, and a first electrode is prepared. The preparation method can effectively improve the utilization rate of the light source, improve the sintering effect of the first electrode paste, and prepare a high-quality first electrode.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a heterojunction solar cell and its preparation method, and a photovoltaic module. Background Technology

[0002] In the preparation of electrode structures for heterojunction solar cells, when a light source is used to sinter the electrode slurry, the electrode slurry, due to its metallic components, reflects part of the light source, resulting in reduced light source utilization. Consequently, the energy of the light source acting on the electrode slurry is lower, the sintering effect is poor, and the performance of the prepared electrode structure is also poor. Summary of the Invention

[0003] This application discloses a heterojunction solar cell and its preparation method, as well as a photovoltaic module. The preparation method of this application can effectively improve the utilization rate of the light source, improve the sintering effect of the first electrode slurry, and prepare a high-quality first electrode.

[0004] In the first aspect, embodiments of this application disclose a method for fabricating a heterojunction solar cell, the method comprising the following steps:

[0005] Printing: Printing a first electrode paste on the first surface of a solar cell semi-finished product; wherein the material of the solar cell semi-finished product includes silicon material and transparent conductive material, the solar cell semi-finished product includes a first surface and a second surface disposed opposite to each other, and the first electrode paste includes a metal material and an organic carrier;

[0006] Incomplete drying: The first electrode slurry is dried so that a portion of the organic carrier is retained in the first electrode slurry.

[0007] In the first photon sintering process, the second surface of the solar cell semi-finished product is irradiated with a light source, the light source being configured to act on the first surface to sinter the first electrode paste and obtain the first electrode.

[0008] Furthermore, in the incomplete drying step, the drying rate of the first electrode slurry is 2% to 8%.

[0009] Furthermore, in the incomplete drying step, the drying time is 15 s to 40 s, and the drying temperature is 80℃ to 190℃.

[0010] Furthermore, in the first photon sintering step, the light source is divergent light, and the energy density of the divergent light is 1 kW / m² to 5 kW / m².

[0011] Furthermore, the wavelength of the diffused light is >1000 nm.

[0012] Furthermore, the power of the emitted light is 2 kW to 3 kW, and the sintering temperature is 150℃ to 200℃.

[0013] Further, the first photon sintering step is carried out under a specified atmosphere, wherein the specified atmosphere includes a non-reactive gas and an oxygen-containing gas, and the mass percentage of the oxygen-containing gas in the specified atmosphere is 5% to 30%.

[0014] Furthermore, after the incomplete drying step and before the first photon sintering step, the preparation method further includes: flipping the first surface so that, in the first photon sintering step, the second surface and the emitter of the light source are located on the same side of the solar cell semi-finished product.

[0015] Furthermore, the solar cell semi-finished product includes a crystal structure, and before the printing step, the preparation method further includes: annealing the solar cell semi-finished product.

[0016] Furthermore, the annealing temperature is 100℃~200℃, and the annealing time is 10 min~50 min.

[0017] Furthermore, a mask is also provided between the emitter of the light source and the semi-finished solar cell;

[0018] The mask is used to block part of the light source so that the blocked light source illuminates the position on the second surface corresponding to the first electrode.

[0019] Further, the first surface is the backlight surface of the solar cell semi-finished product, and the second surface is the light-receiving surface of the solar cell semi-finished product; prior to the printing step, the preparation method further includes:

[0020] A first intrinsic silicon passivation layer and a second intrinsic silicon passivation layer are respectively prepared on the first surface and the second surface of the silicon substrate;

[0021] A first doped silicon layer is prepared on the surface of the first intrinsic silicon passivation layer, and a second doped silicon layer is prepared on the surface of the second intrinsic silicon passivation layer;

[0022] A first transparent conductive layer is prepared on the first doped silicon layer, and a second transparent conductive layer is prepared on the second doped silicon layer to obtain the solar cell semi-finished product;

[0023] In this process, one of the first doped silicon layer and the second doped silicon layer is an N-type doped silicon layer and the other is a P-type doped silicon layer.

[0024] Furthermore, after the first photon sintering step, the preparation method further includes: printing a second electrode paste on the second surface of the solar cell semi-finished product, performing a second photon sintering on the second electrode paste on the second surface to obtain the second electrode; and / or,

[0025] The metallic material is at least one of silver-plated copper or copper; and / or,

[0026] The emitter of the light source includes at least one of a ceramic lamp tube and a gold-plated lamp tube; and / or,

[0027] A filter is also provided between the emitter of the light source and the semi-finished solar cell, and the filter is used to adjust the wavelength of the light source.

[0028] Secondly, embodiments of this application disclose a heterojunction solar cell, wherein the heterojunction solar cell includes the heterojunction solar cell prepared by the preparation method described in any one of the first aspects.

[0029] Thirdly, embodiments of this application disclose a photovoltaic module, which includes the heterojunction solar cell described in the second aspect.

[0030] Compared with the prior art, the beneficial effects of this application are as follows: This application provides a heterojunction solar cell and its preparation method, as well as a photovoltaic module. The preparation method of this application can effectively improve the utilization rate of the light source, improve the sintering effect of the first electrode slurry, and prepare a high-quality first electrode.

[0031] Specifically, this application first prints a first electrode paste on the first surface of a solar cell semi-finished product; then, the printed first electrode paste is partially dried, so that some organic carrier remains in the dried first electrode paste, thereby giving the first electrode paste certain flow characteristics, rather than being completely solidified and unable to flow.

[0032] Next, in the first photonic sintering step, this application does not directly irradiate the first surface printed with the first electrode paste with a light source to sinter the first electrode paste. Instead, it irradiates the opposite side of the first surface, i.e., the second surface without the first electrode paste, to improve light source utilization and sintering quality. Since the materials of the solar cell semi-finished product include silicon and transparent conductive materials, both of which have good transmittance characteristics for long-wavelength light, long-wavelength light can penetrate from the second surface to the first surface, achieving indirect sintering of the first electrode paste. In this sintering method, because the light source enters from the second surface without the electrode paste, the reflection effect of the second surface on the light source is weak, allowing more light to effectively reach the first surface, thus contributing to a higher degree of full utilization of the light source. Based on this, since the first electrode slurry has a certain fluidity and the light source has a high utilization rate, the process of sintering to form the electrode by the light source will not only accelerate the diffusion ability of each component in the first electrode slurry, making each component approach and contact each other, thus improving the compactness of the electrode structure, but also improve the sufficiency of the reaction between each component, reduce the degree of crystal defects, and promote crystal growth, thereby preparing a first electrode with high crystal quality. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a process flow diagram of the first heterojunction solar cell fabrication method provided in the embodiments of this application;

[0035] Figure 2 This is a schematic diagram of the first photon sintering step provided in the embodiments of this application;

[0036] Figure 3 This is a schematic diagram of the second type of first photon sintering step provided in the embodiments of this application;

[0037] Figure 4 This is a process flow diagram of the second type of heterojunction solar cell fabrication method provided in the embodiments of this application;

[0038] Figure 5 This is a process flow diagram of the third heterojunction solar cell fabrication method provided in the embodiments of this application;

[0039] Figure 6 This is a schematic diagram of the third first photon sintering step provided in the embodiments of this application;

[0040] Figure 7 This is a schematic diagram of the structure of a heterojunction solar cell provided in an embodiment of this application;

[0041] Figure 8 This is a scanning electron microscope image of the first electrode before the first photon sintering provided in the embodiments of this application;

[0042] Figure 9 This is a scanning electron microscope image of the first electrode after first photon sintering, provided in an embodiment of this application.

[0043] Icons: 1. Semi-finished solar cell; 1a. First surface; 1b. Second surface; 11. Silicon substrate; 12. First intrinsic silicon passivation layer; 13. First doped silicon layer; 14. First transparent conductive layer; 15. Second intrinsic silicon passivation layer; 16. Second doped silicon layer; 17. Second transparent conductive layer; 2. First electrode; 3. Emitter; 4. Filter; 5. Photomask; 6. Second electrode. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0046] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0047] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0048] The technical solutions provided by the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0049] In the electrode fabrication process of heterojunction solar cells, the light source is often directly irradiated onto the electrode paste for sintering. Since the main component of the electrode paste is metal, which easily reflects light, this irradiation method results in a high degree of light reflection, leading to lower light source utilization.

[0050] Although the occurrence of light source reflection can be reduced by increasing the amount of light source or changing the incident angle of the light source, the above-mentioned improvement methods are not effective enough in reducing the degree of light source reflection, and therefore it is still difficult to effectively make full use of the light source.

[0051] Based on the above problems, this application provides a heterojunction solar cell and its preparation method, as well as a photovoltaic module. The preparation method of this application can effectively improve the utilization rate of the light source, improve the sintering effect of the first electrode, and prepare a high-quality first electrode.

[0052] This application discloses a method for fabricating a heterojunction solar cell, such as... Figure 1 and Figure 2 As shown, the preparation method includes the following steps:

[0053] Printing: Printing a first electrode paste on the first surface 1a of the solar cell semi-finished product 1; wherein, the material of the solar cell semi-finished product 1 includes silicon material and transparent conductive material, the solar cell semi-finished product 1 includes a first surface 1a and a second surface 1b arranged opposite to each other, and the first electrode paste includes metal material and organic carrier.

[0054] Incomplete drying: The first electrode slurry is dried so that some of the organic carrier is retained in the first electrode slurry.

[0055] In the first photon sintering process, the second surface 1b of the solar cell semi-finished product 1 is irradiated with a light source, and the light source is configured to act on the first surface 1a to sinter the first electrode paste and obtain the first electrode 2.

[0056] Among them, the solar cell semi-finished product 1 refers to the semi-finished product that has been prepared with other functional film layers but lacks electrode structure; one of the first surface 1a and the second surface 1b is the light-receiving surface of the solar cell, and the other is the back-lighting surface of the solar cell; the silicon-containing layer structure made of silicon material as the main material includes at least one of silicon substrate 11, doped silicon layer, and intrinsic silicon passivation layer; the transparent conductive material can be at least one of indium tin oxide and indium zinc oxide; long-wavelength light refers to light with relatively long wavelengths in the electromagnetic spectrum, such as wavelengths greater than 700 nm.

[0057] This application first prints a first electrode paste on the first surface 1a of the solar cell semi-finished product 1; then, the printed first electrode paste is partially dried, so that some organic carrier remains in the dried first electrode paste, thus making the dried first electrode paste have suitable flow characteristics.

[0058] Next, in the first photonic sintering step, this application does not directly irradiate the first surface 1a, on which the first electrode paste is printed, with a light source to sinter the first electrode paste. Instead, it irradiates the opposite side of the first surface 1a, namely the second surface 1b, on which the first electrode paste is not placed, to improve the utilization rate of the light source and the sintering quality. Since the materials of the solar cell semi-finished product 1 include silicon and transparent conductive materials, both of which have good transmittance characteristics for long-wavelength light, long-wavelength light can penetrate from the second surface 1b to the first surface 1a, achieving indirect sintering of the first electrode paste. In this sintering method, since the light source enters from the second surface 1b, on which the electrode paste is not printed, the reflection effect of the second surface 1b on the light source is weak, and more light can effectively reach the first surface 1a, contributing to a higher degree of full utilization of the light source.

[0059] Furthermore, since the first electrode slurry has a certain fluidity and high light source utilization, during the sintering process, it will not only accelerate the diffusion ability of each component in the first electrode slurry, making each component approach and contact each other, thus improving the compactness of the electrode structure, but also improve the sufficiency of the reaction between each component, reduce crystal defects, and promote crystal growth, thereby preparing a first electrode 2 with high crystal quality.

[0060] In summary, the preparation method of this application can effectively improve the utilization rate of the light source, thereby helping to improve the diffusion ability of each component in the first electrode slurry and improve the reaction sufficiency of each component, thus preparing a first electrode 2 with high density and few crystal defects.

[0061] In addition, the metallic material is at least one of silver-plated copper or copper.

[0062] Furthermore, in the incomplete drying step, the drying rate of the first electrode slurry is 2% to 8%.

[0063] Drying rate indicates the degree of drying of the first electrode slurry. The formula for calculating the drying rate is:

[0064] w=(m1-m2) / m1;

[0065] Where m1 represents the mass of the solar cell semi-finished product 1 containing the first electrode slurry before drying, in g;

[0066] m2 represents the mass of the dried solar cell semi-finished product 1 containing the first electrode slurry, in grams;

[0067] w represents the drying rate, expressed as a percentage.

[0068] This application achieves suitable flow characteristics of the first electrode slurry by keeping its drying rate within the aforementioned range. This allows for effective utilization of the flow characteristics of the first electrode slurry during the first photonic sintering step, promoting the diffusion of components within the slurry and thus contributing to further improving the density of the first electrode 2 structure. Examples of drying rates include 2%, 3%, 4%, 6%, and 8%.

[0069] In addition, it should be noted that the control of drying parameters in this application is to achieve a drying rate of 2% to 8% for the first electrode slurry. Different types of electrode slurries require different drying parameters to be controlled in the incomplete drying step. This application does not limit the specific drying parameters, as long as the drying effect of this application can be achieved.

[0070] In one optional embodiment, during the incomplete drying step, the drying time is 15 s to 40 s, and the drying temperature is 80℃ to 190℃. When the drying parameters are within the above range, the drying rate of the first electrode slurry can be effectively ensured, thereby making the flow characteristics of the first electrode slurry within a more suitable range, which in turn helps to form a first electrode 2 with higher density and fewer defects. For example, the drying time is 15 s, 20 s, 30 s, 35 s, 40 s, etc.; and the drying temperature is 80℃, 100℃, 140℃, 160℃, 190℃, etc.

[0071] In one optional embodiment, the light source in the first photon sintering step is a laser. In another optional embodiment, the light source in the first photon sintering step is divergent light. The energy density of the divergent light is 1 kW / m² to 5 kW / m². For heterojunction solar cells, since the electrode structure of the heterojunction solar cell is in ohmic contact with the transparent conductive layer, and the electrode structure is directly disposed on the transparent conductive layer, the heterojunction solar cell does not need to be burned through, and the electrode structure can be fabricated by using a low-temperature process. Specifically, during the first photon sintering, since the emitted light has a lower energy density than the laser and the divergence effect of the light source is better, the sintering temperature rises slowly and the temperature uniformity is higher during the sintering process. This helps to avoid the generation of local hot spots and makes the sintering effect more consistent. This sintering method not only helps to reduce thermal damage to sensitive materials (such as silicon materials and transparent conductive materials) in the non-electrode areas of the solar cell semi-finished product 1, effectively avoiding damage to the non-electrode areas, but also helps to disrupt the thermodynamic balance between materials in the solar cell semi-finished product 1. For example, the energy density of the diffused light is 1 kW / m², 2 kW / m², 3 kW / m², 4 kW / m², 5 kW / m², etc.

[0072] Optionally, when the light source is diffuse light, the emitter 3 of the corresponding light source includes at least one of ceramic lamp tube and gold-plated lamp tube.

[0073] Furthermore, the wavelength of the diffused light is >1000 nm. This wavelength is the lowest point of the absorption valley for silicon and transparent conductive materials. When the wavelength of the diffused light is within the above range, the absorption of light by the solar cell semi-finished product 1 at the above wavelength is minimal, which helps to further avoid damage to the solar cell semi-finished product 1 and effectively ensures the sintering effect. For example, the wavelength of the diffused light is 1010 nm, 1100 nm, 1500 nm, 2000 nm, 3000 nm, etc.

[0074] In addition, such as Figure 3 As shown, the wavelength range of the diffused light is selected by setting a filter 4 between the emitter 3 of the light source and the solar cell semi-finished product 1. The filter 4 can effectively filter wavelengths of different bands, thereby better controlling the wavelength acting on the solar cell semi-finished product 1 to be within the above range.

[0075] Furthermore, the power of the diffused light is 2 kW to 3 kW, and the sintering temperature is 150℃ to 200℃. When the power of the diffused light and the sintering temperature are within the above ranges, the sintering effect is higher, which is more conducive to promoting the migration of various components in the first electrode slurry, thereby helping to form a higher quality first electrode 2. For example, the power of the diffused light is 2 kW, 2.2 kW, 2.4 kW, 2.7 kW, 3 kW, etc.; and the sintering temperature is 150℃, 160℃, 170℃, 180℃, 200℃, etc.

[0076] Furthermore, the first photon sintering step is carried out under a specified atmosphere, which includes non-reactive gases and oxygen-containing gases, and the mass percentage of oxygen-containing gases in the specified atmosphere is 5% to 30%.

[0077] Non-reactive gases refer to gases that do not participate in the reaction of the first electrode slurry, including at least one of nitrogen, argon, and helium; oxygen-containing gases include oxygen.

[0078] The specified atmosphere in this application includes non-reactive gases and oxygen-containing gases, and the mass percentage of oxygen-containing gases is controlled within the aforementioned range. Therefore, the oxygen-containing gases can effectively react with the components in the first electrode slurry and participate in the reaction process of the first electrode slurry, which helps to further improve the crystallization effect and reduce the formation of defects. For example, the mass percentage of oxygen-containing gases is 5%, 10%, 15%, 25%, 30%, etc.

[0079] In one alternative embodiment, after the incomplete drying step and before the solar cell semi-finished product 1 is fed into the first photon sintering equipment, the emitter 3 of the light source and the second surface 1b are located on the same side of the solar cell semi-finished product 1. Therefore, when the solar cell semi-finished product 1 is fed into the first photon sintering equipment, the light source can directly irradiate the second surface 1b of the solar cell semi-finished product 1, which helps to improve the processing efficiency.

[0080] In another alternative implementation, such as Figure 4 As shown, after the incomplete drying step and before the solar cell semi-finished product 1 is fed into the first photon sintering equipment, the emitter 3 of the light source and the second surface 1b are located on different sides of the solar cell semi-finished product 1. Therefore, in order to achieve irradiation of the second surface 1b by the light source, the preparation method further includes: flipping the first surface 1a so that the second surface 1b and the emitter 3 are located on the same side of the solar cell semi-finished product 1. In this embodiment, by further controlling the drying rate within the range of 2% to 8%, the flow characteristics of the first electrode slurry are made suitable, thereby helping to avoid the problem of excessive flow of the first electrode slurry during the flipping process, which leads to an increased coverage area of ​​the first electrode slurry and low solar energy utilization.

[0081] Furthermore, the solar cell semi-finished product 1 includes a crystal structure. For example... Figure 5 As shown, prior to the printing step, the preparation method further includes annealing the solar cell semi-finished product 1. Since the solar cell semi-finished product 1 of this application includes a crystal structure, annealing promotes the rearrangement of atoms in the solar cell semi-finished product 1. Under the induction of the crystal structure, the atoms are arranged into a regular structure, which helps to increase the crystallization rate of the solar cell semi-finished product 1. Furthermore, the increased crystallization rate of the solar cell semi-finished product 1 helps to increase the transmittance of long-wavelength light, thus facilitating the effective penetration of light irradiated onto the second surface 1b to the first surface 1a in the subsequent first photon sintering step, thereby further forming a first electrode 2 with higher crystal quality, fewer defects, greater density, and lower resistance.

[0082] A crystal structure refers to a regular arrangement of atoms. In this application, the silicon material and the transparent conductive material in the heterojunction solar cell contain this crystal structure. Specifically, in the heterojunction solar cell, the doped silicon layer formed by the silicon material and the transparent conductive layer formed by the transparent conductive material contain this crystal structure.

[0083] Furthermore, the annealing temperature is 100℃~200℃, and the annealing time is 10 min~50 min.

[0084] When the annealing parameters are within the above range, it is more conducive to improving the crystallinity of the solar cell semi-finished product 1, thereby making the light transmittance of long-wavelength light stronger and more conducive to the preparation of a high-quality first electrode 2. For example, the annealing temperature is 100℃, 160℃, 170℃, 180℃, 200℃, etc.; the annealing time is 10 min, 20 min, 30 min, 40 min, 50 min, etc.

[0085] Furthermore, such as Figure 6 As shown, a mask 5 is also provided between the emitter 3 of the light source and the solar cell semi-finished product 1. The position of the mask 5 corresponds to the area outside the position of the first electrode 2 on the solar cell semi-finished product 1.

[0086] The mask is used to partially block the light source so that the blocked light source illuminates the second surface 1b corresponding to the position of the first electrode 2. By adding the mask 5, patterned illumination of light is achieved, causing the light to only illuminate the second surface 1b corresponding to the position of the first electrode 2. This effectively avoids adverse effects on the heat-sensitive materials in the non-electrode areas, further preventing damage to the non-electrode areas, and thus helping to further improve the performance of the heterojunction solar cell.

[0087] Furthermore, the first surface 1a is the backlight surface of the solar cell semi-finished product 1, and the second surface 1b is the light-receiving surface of the solar cell semi-finished product 1; prior to the printing step, the preparation method further includes:

[0088] A first intrinsic silicon passivation layer and a second intrinsic silicon passivation layer are respectively formed on the first surface 1a and the second surface 1b of the silicon substrate 11;

[0089] A first doped silicon layer is prepared on the surface of the first intrinsic silicon passivation layer, and a second doped silicon layer is prepared on the surface of the second intrinsic silicon passivation layer.

[0090] A first transparent conductive layer is prepared on a first doped silicon layer, and a second transparent conductive layer is prepared on a second doped silicon layer to obtain a solar cell semi-finished product 1.

[0091] Among them, one of the first doped silicon layer and the second doped silicon layer is an N-type doped silicon layer and the other is a P-type doped silicon layer.

[0092] For heterojunction solar cells, the linear resistance of the electrodes on the light-receiving side is subject to higher requirements. Therefore, the silver content in the electrode paste used on the light-receiving side is higher than that on the back-lighting side. Consequently, the back-lighting side has a lower silver content in its electrode paste, leading to an increase in the linear resistance of its electrode structure. The method described in this application helps to further reduce the linear resistance of the electrode structure on the back-lighting side. In other words, for the back-lighting side, the electrode structure reduces both cost and linear resistance.

[0093] Furthermore, after the first photon sintering step, the preparation method further includes: printing a second electrode paste on the second surface 1b of the solar cell semi-finished product 1, and performing a second photon sintering on the second electrode paste on the second surface 1b to obtain the second electrode.

[0094] This application also discloses a heterojunction solar cell, which includes the heterojunction solar cell prepared by the above-described preparation method.

[0095] In one alternative implementation, such as Figure 7As shown, the structure of the solar cell semi-finished product 1 in the heterojunction solar cell of this application includes: a second intrinsic silicon passivation layer 15, a second doped silicon layer 16, and a second transparent conductive layer 17 sequentially disposed on the second surface 1b of the silicon substrate 11; a first intrinsic silicon passivation layer 12, a first doped silicon layer 13, and a first transparent conductive layer 14 sequentially disposed on the first surface 1a of the silicon substrate 11; wherein, the heterojunction solar cell also includes a second electrode 6, the second electrode 6 is disposed on the side of the second transparent conductive layer 17 away from the second doped silicon layer 16 and is in ohmic contact with the second transparent conductive layer 17; a first electrode 2 is disposed on the side of the first transparent conductive layer 14 away from the first doped silicon layer 13 and is in ohmic contact with the first transparent conductive layer 14; wherein, one of the first electrode 2 and the second electrode 6 is a positive electrode and the other is a negative electrode; one of the first doped silicon layer 13 and the second doped silicon layer 16 is an N-type doped silicon layer and the other is a P-type doped silicon layer; one of the first surface 1a and the second surface 1b is a light-receiving surface and the other is a backlighting surface.

[0096] This application also discloses a photovoltaic module, which includes the above-mentioned heterojunction solar cell.

[0097] The technical solution of this application will be further explained below with reference to more specific embodiments and experimental test results.

[0098] Example 1:

[0099] This application provides a method for fabricating a heterojunction solar cell.

[0100] The steps for preparing semi-finished solar cells include:

[0101] Texturing of N-type silicon substrates;

[0102] A first intrinsic silicon passivation layer with a thickness of 6 nm was prepared on the first surface of a silicon substrate using PECVD; a second intrinsic silicon passivation layer with a thickness of 5 nm was prepared on the second surface of the silicon substrate using PECVD, wherein the first surface is the backlight surface and the second surface is the light-receiving surface;

[0103] A second doped silicon layer with a thickness of 35 nm was deposited on the first intrinsic silicon passivation layer using PECVD. This second doped silicon layer is a P-type doped silicon layer. A second doped silicon layer with a thickness of 20 nm was deposited on the second intrinsic silicon passivation layer using PECVD. This second doped silicon layer is an N-type doped silicon layer.

[0104] A first transparent conductive layer is prepared on a first doped silicon layer using PVD; a second transparent conductive layer is prepared on a second doped silicon layer to obtain a solar cell semi-finished product, which includes a crystal structure.

[0105] The semi-finished solar cell was annealed at a temperature of 190°C for 45 minutes.

[0106] Printing involves printing a first electrode paste on the back surface of a semi-finished solar cell. The semi-finished solar cell is made of silicon and transparent conductive materials, and the first electrode paste is made of metal and organic carrier. The metal material includes silver-coated copper.

[0107] The first electrode slurry is not completely dried, so that some of the organic carrier is retained in the first electrode slurry. The drying rate of the first electrode slurry is 5%, the drying time is 25 s, and the drying temperature is 180℃.

[0108] The steps of first photon sintering include:

[0109] Since the emitter and backlight of the light source are located on the same side of the semi-finished solar cell, the backlight is first flipped so that the light-receiving surface and the emitter are located on the same side of the semi-finished solar cell; the emitter of the light source is a ceramic lamp tube.

[0110] The solar cell semi-finished product is irradiated with a light source on its light-receiving surface under a specified atmosphere. The light source is configured to act on the back surface to sinter the first electrode paste, thereby obtaining the first electrode. The specified atmosphere includes nitrogen and oxygen with a mass percentage of 10%, and the light source is diffuse light with an energy density of 2.4 kW / m². 2 The wavelength is 1050 nm to 1500 nm, the power of the diffused light is 2.4 kW, and the sintering temperature is 180℃.

[0111] A second electrode paste is printed on the light-receiving surface of a solar cell semi-finished product, and the second electrode paste on the light-receiving surface is subjected to second photon sintering to obtain the second electrode.

[0112] Example 2:

[0113] The difference between this embodiment and Embodiment 1 is that, in the incomplete drying step, the drying rate of the first electrode slurry is 2%.

[0114] Example 3:

[0115] The difference between this embodiment and Embodiment 1 is that, in the incomplete drying step, the drying rate of the first electrode slurry is 8%.

[0116] Example 4:

[0117] The difference between this embodiment and Embodiment 1 is that, in the incomplete drying step, the drying rate of the first electrode slurry is 10%.

[0118] Example 5:

[0119] The difference between this embodiment and Embodiment 1 is that, in the specified atmosphere, the mass percentage of oxygen-containing gas is 5%.

[0120] Example 6:

[0121] The difference between this embodiment and Embodiment 1 is that, in the specified atmosphere, the mass percentage of oxygen-containing gas is 30%.

[0122] Example 7:

[0123] The difference between this embodiment and Embodiment 1 is that, in the specified atmosphere, the mass percentage of oxygen-containing gas is 0%, that is, the specified atmosphere only includes nitrogen.

[0124] Example 8:

[0125] The difference between this embodiment and Embodiment 1 is that the solar cell semi-finished product is not annealed; that is, the first electrode paste is directly printed on the prepared solar cell semi-finished product.

[0126] Example 9:

[0127] The difference between this application and Embodiment 1 is that a mask is provided between the emitter of the light source and the semi-finished solar cell, and the mask makes the light source only act on the light-receiving surface corresponding to the position of the first electrode.

[0128] Comparative Example 1:

[0129] The difference between this comparative example and Example 1 is that in Example 1, the light-receiving surface of the solar cell semi-finished product is irradiated with a light source under a specified atmosphere during the first photon sintering step, while in this comparative example, the back surface of the solar cell semi-finished product is irradiated with a light source to sinter the first electrode paste.

[0130] Comparative Example 2:

[0131] The difference between this comparative example and Example 1 is that the first electrode slurry is completely dried, meaning that no organic carrier is retained in the dried first electrode slurry.

[0132] Comparative Example 3:

[0133] The difference between this comparative example and Example 1 is that after the first electrode paste is printed on the backlight side, it is dried, and then the second electrode paste is printed on the light-receiving side. The solar cell semi-finished product is sent into the curing furnace for sintering to obtain the first electrode structure and the second electrode structure.

[0134] Structural testing:

[0135] like Figure 8 and Figure 9 As shown, Figure 8 This is a scanning electron microscope (SEM) image of the first electrode paste before the first photon sintering. Figure 9The image shows a scanning electron microscope (SEM) image of the first electrode paste after first photon sintering. As can be seen from the image, compared with the first electrode paste before first photon sintering, the first electrode paste of this application has higher density after first photon sintering. This is because the preparation method of this application can effectively improve the utilization rate of the light source, thus helping to improve the diffusion ability of each component of the first electrode paste and improve the reaction sufficiency of each component, thereby helping to prepare a first electrode of higher quality.

[0136] Performance testing

[0137] The line resistance of the first electrode of the heterojunction solar cells prepared in Examples 1 to 9 and Comparative Examples 1 to 3 was tested. The line resistance of the first electrode was tested using the Transmission Line Model (TLM) method. The experimental test results are shown in Table 1. Table 1 shows the test results of the line resistance of the first electrode.

[0138] Table 1 Test results of the first electrode line resistance

[0139]

[0140] Analysis of the data from Example 1 and Comparative Example 1 shows that the line resistance of the first electrode in Example 1 is better than that in Comparative Example 1. This demonstrates that indirectly sintering the first electrode paste on the first surface (i.e., the backlight surface in Example 1) by utilizing the long-wavelength light transmittance characteristics of the second surface (i.e., the light-receiving surface in Example 1) allows more light to effectively reach the first surface, contributing to a higher degree of full utilization of the light source. In contrast, Comparative Example 1 directly irradiates the backlight surface of the solar cell semi-finished product. Since the backlight surface already has electrode paste printed on it, the light source cannot be fully utilized.

[0141] Analysis of the data from Examples 1 to 4 and Comparative Example 2 shows that the line resistance of the first electrode in Examples 1 to 4 is better than that in Comparative Example 2. This indicates that during the drying of the first electrode slurry, some organic carrier remains in the slurry, exhibiting certain flow characteristics, which results in a highly compact structure and good crystal quality in the prepared first electrode.

[0142] In the data analysis of Examples 1 to 4, it was found that the line resistance of the first electrode in Examples 1 to 3 was better than that in Example 4. This indicates that the drying rate in Examples 1 to 3 is more suitable, and a more suitable drying rate helps to further prepare a first electrode with higher density and better crystal quality.

[0143] Analysis of the data from Example 1 and Comparative Example 3 shows that the line resistance of the first electrode in Example 1 is better than that in Comparative Example 3. This indicates that the photonic sintering method provides stronger energy, which helps to prepare a first electrode with a better structure. In contrast, the sintering method using a curing furnace in Comparative Example 3 results in a significant amount of energy being consumed in non-target areas (such as the furnace body and carrier) during sintering, leading to lower energy applied to the first electrode and a poorer sintering effect.

[0144] Analysis of the data from Examples 1, 5 to 7 shows that the line resistance of the first electrode in Examples 1, 5, and 6 is better than that in Example 7. This indicates that during sintering in a specified atmosphere, by introducing oxygen-containing gas and controlling its content, the oxygen-containing gas can effectively react with the components in the first electrode slurry, which helps to further improve the crystal structure of the first electrode.

[0145] Analysis of the data from Examples 1 and 8 shows that the line resistance of the first electrode in Example 1 is better than that in Example 8. This demonstrates that annealing the semi-finished solar cell can effectively improve the crystallization rate of the crystal structure in the semi-finished solar cell, thereby helping to increase the transmittance of long-wavelength light and producing a first electrode with a better structure.

[0146] Analysis of the data from Embodiment 1 and Embodiment 9 shows that the line resistance of the first electrode in Embodiment 1 is better than that in Embodiment 9. This demonstrates that by using a mask, the light source acts only on the light-receiving surface corresponding to the position of the first electrode, thus helping to ensure the sintering effect of the first electrode while avoiding damage to non-electrode areas.

[0147] The electrode structure and its preparation method, heterojunction solar cell, and photovoltaic module disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the electrode structure and its preparation method, heterojunction solar cell, and photovoltaic module. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for fabricating a heterojunction solar cell, characterized in that, The preparation method includes the following steps: Printing: Printing a first electrode paste on the first surface of a solar cell semi-finished product; wherein the material of the solar cell semi-finished product includes silicon material and transparent conductive material, the solar cell semi-finished product includes a first surface and a second surface disposed opposite to each other, and the first electrode paste includes a metal material and an organic carrier; Incomplete drying: The first electrode slurry is dried so that a portion of the organic carrier is retained in the first electrode slurry. In the first photon sintering process, the second surface of the solar cell semi-finished product is irradiated with a light source, the light source being configured to act on the first surface to sinter the first electrode paste and obtain the first electrode.

2. The preparation method according to claim 1, characterized in that, In the incomplete drying step, the drying rate of the first electrode slurry is 2% to 8%.

3. The preparation method according to claim 1, characterized in that, In the incomplete drying step, the drying time is 15 s to 40 s and the drying temperature is 80℃ to 190℃.

4. The preparation method according to claim 1, characterized in that, In the first photon sintering step, the light source is divergent light, and the energy density of the divergent light is 1 kW / m² to 5 kW / m².

5. The preparation method according to claim 4, characterized in that, The wavelength of the emitted light is >1000 nm.

6. The preparation method according to claim 4, characterized in that, The power of the emitted light is 2 kW to 3 kW, and the sintering temperature is 150℃ to 200℃.

7. The preparation method according to claim 1, characterized in that, The first photon sintering step is performed under a specified atmosphere, wherein the specified atmosphere includes a non-reactive gas and an oxygen-containing gas, and the mass percentage of the oxygen-containing gas in the specified atmosphere is 5% to 30%.

8. The preparation method according to any one of claims 1 to 7, characterized in that, After the incomplete drying step and before the first photon sintering step, the preparation method further includes: flipping the first surface so that, in the first photon sintering step, the second surface and the emitter of the light source are located on the same side of the solar cell semi-finished product.

9. The preparation method according to claim 1, characterized in that, The solar cell semi-finished product includes a crystal structure. Before the printing step, the preparation method further includes annealing the solar cell semi-finished product.

10. The preparation method according to claim 9, characterized in that, The annealing temperature is 100℃~200℃, and the annealing time is 10 min~50 min.

11. The preparation method according to claim 1, characterized in that, A mask is also provided between the emitter of the light source and the semi-finished solar cell. The mask is used to block part of the light source so that the blocked light source illuminates the position on the second surface corresponding to the first electrode.

12. The preparation method according to claim 1, characterized in that, The first surface is the backlight surface of the solar cell semi-finished product, and the second surface is the light-receiving surface of the solar cell semi-finished product. Prior to the printing step, the preparation method further includes: A first intrinsic silicon passivation layer and a second intrinsic silicon passivation layer are respectively prepared on the first surface and the second surface of the silicon substrate; A first doped silicon layer is prepared on the surface of the first intrinsic silicon passivation layer, and a second doped silicon layer is prepared on the surface of the second intrinsic silicon passivation layer; A first transparent conductive layer is prepared on the first doped silicon layer, and a second transparent conductive layer is prepared on the second doped silicon layer to obtain the solar cell semi-finished product; In this process, one of the first doped silicon layer and the second doped silicon layer is an N-type doped silicon layer and the other is a P-type doped silicon layer.

13. The preparation method according to any one of claims 9 to 12, characterized in that, Following the first photon sintering step, the preparation method further includes: printing a second electrode paste on the second surface of the solar cell semi-finished product, and performing a second photon sintering on the second electrode paste on the second surface to obtain the second electrode; and / or, The metallic material is at least one of silver-plated copper or copper; and / or, The emitter of the light source includes at least one of a ceramic lamp tube and a gold-plated lamp tube; and / or, A filter is also provided between the emitter of the light source and the semi-finished solar cell, and the filter is used to adjust the wavelength of the light source.

14. A heterojunction solar cell, characterized in that, The heterojunction solar cell includes the heterojunction solar cell prepared by the preparation method according to any one of claims 1 to 13.

15. A photovoltaic module, characterized in that, The photovoltaic module includes the heterojunction solar cell as described in claim 14.

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