Solar cell and method of manufacturing the same, photovoltaic module

Abstract

This application relates to the field of solar cells, and more particularly to solar cells and their fabrication methods, and photovoltaic modules. The solar cell includes: a substrate having a first surface and a second surface disposed opposite to each other; a first intrinsic layer and a first doped conductive layer sequentially disposed on the first surface; wherein, along the direction from the substrate to the first doped conductive layer, the first intrinsic layer sequentially includes a first amorphous phase layer and a first crystalline phase layer, the first amorphous phase layer being in direct contact with the first surface of the substrate, and the first doped conductive layer being in direct contact with the surface of the first crystalline phase layer; the doping atoms of the first doped conductive layer include at least one of boron and gallium. This application, by adjusting the structure of the first intrinsic layer in the solar cell, improves the epitaxial growth of the first intrinsic layer while reducing defects in the first doped conductive layer. Through the synergistic effect of these two aspects, the carrier lifetime is extended, and the photoelectric performance of the solar cell is improved.

Description

Technical Field

[0001] This application relates to the field of solar cells, and in particular to solar cells and their preparation methods, and photovoltaic modules. Background Technology

[0002] In solar cells, carrier recombination during transport leads to a decrease in photoelectric performance. Epitaxial growth of the intrinsic layer increases defects at the interface with the substrate, exacerbating carrier recombination. Defects in the doped conductive layer also intensify carrier recombination. Summary of the Invention

[0003] This application discloses a solar cell and its preparation method, as well as a photovoltaic module, to improve the recombination problem of charge carriers during the transport process and enhance the transport efficiency of charge carriers.

[0004] To achieve the above objectives, in a first aspect, this application discloses a solar cell, said solar cell comprising: The substrate has a first surface and a second surface disposed opposite to each other; A first intrinsic layer and a first doped conductive layer are sequentially disposed on the first surface; wherein, along the direction from the substrate to the first doped conductive layer, the first intrinsic layer sequentially includes a first amorphous phase layer and a first crystalline phase layer, the first amorphous phase layer is in direct contact with the first surface of the substrate, and the first doped conductive layer is in direct contact with the surface of the first crystalline phase layer; The doping atoms of the first doped conductive layer include at least one of boron and gallium.

[0005] Furthermore, the crystalline phases in the first crystalline phase layer are discontinuously distributed along a plane perpendicular to the thickness direction of the solar cell; and / or, The crystallinity of the first crystalline phase layer is 20%~35%; and / or, The doping concentration of the doped atoms in the first doped conductive layer is 10. 16 pcs / cm 3 ~10 21 pcs / cm 3 ; and / or, The substrate <001> Zone axis orientation and the first crystal phase layer <001> Different zone axis orientations; and / or, The thickness of the first amorphous phase layer is 2.5 nm to 12.5 nm, and the thickness of the first crystalline phase layer is 1 nm to 8 nm.

[0006] Furthermore, the solar cell is a heterojunction cell, which further includes: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer facing away from the first intrinsic layer; a second intrinsic layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the second surface of the substrate, wherein one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode, and the doping atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic; or, The solar cell is a heterojunction back-contact cell, further comprising: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer facing away from the first intrinsic layer; a second intrinsic layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the first surface of the substrate, wherein the first intrinsic layer and the second intrinsic layer are spaced apart on the first surface of the substrate and separated by an isolation region; the doping atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic, wherein one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; or, The solar cell is a composite passivated back contact solar cell, which further includes: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer facing away from the first intrinsic layer; a dielectric layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the first surface of the substrate; the dielectric layer and the first intrinsic layer are disposed on the first surface of the substrate at a distance, and the dielectric layer and the first intrinsic layer are separated by an isolation region; the doped atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic, and one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode.

[0007] Secondly, this application provides a method for fabricating a solar cell, wherein the solar cell is the solar cell described in the first aspect, and the fabrication method includes the following steps: A wet-processed substrate has a first surface and a second surface disposed opposite to each other, such that an adsorbent is present on the first surface of the substrate; Preparation of the first intrinsic layer: Under vacuum conditions, a first amorphous phase layer and a first crystalline phase layer are sequentially prepared on the first surface where the adsorbent is present by chemical vapor deposition, and the adsorbent is removed during the preparation of the first amorphous phase layer and the first crystalline phase layer, and the first amorphous phase layer is in direct contact with the substrate. A first doped conductive layer is prepared on the surface of the first crystalline phase layer opposite to the first amorphous phase layer, wherein the doping atoms of the first doped conductive layer include at least one of boron and gallium.

[0008] Further, the wet treatment step of the substrate includes: treating the substrate with a wet solution at 25℃~75℃ for 120 s~400 s and then rinsing with water. The wet solution includes a cleaning agent and the adsorbent. The cleaning agent includes any one of hydrochloric acid-hydrogen peroxide mixed solution and hydrofluoric acid. The adsorbent contains at least one of citrate, sulfonate, hydroxyl, ether, carboxylate, and acetate. The mass fraction of the adsorbent in the wet solution is 0.02%~0.7%.

[0009] Furthermore, the adsorbent includes at least one of sodium citrate, sodium dodecyl sulfonate, ethylene glycol monobutyl ether, isopropanol, sodium benzoate, sodium acetate, polyoxyethylene ether, and sodium dodecyl sulfonate.

[0010] Further, the cleaning agent is the hydrochloric acid-hydrogen peroxide mixed solution, and the wet solution comprises 5 wt%~10 wt% hydrochloric acid, 5 wt%~7.5 wt% hydrogen peroxide, 0.10 wt%~0.16 wt% sodium citrate, 0.04 wt%~0.06 wt% sodium dodecyl sulfonate, 0.04 wt%~0.16 wt% ethylene glycol monobutyl ether, and 0.15 wt%~0.30 wt% isopropanol; the treatment temperature is 20℃~50℃, and the treatment time is 120 s~310 s; or, The cleaning agent is hydrofluoric acid, and the wet solution comprises 2 wt% to 8 wt% hydrofluoric acid, 0.01 wt% to 0.03 wt% sodium benzoate, 0.02 wt% to 0.04 wt% sodium acetate, 0.01 wt% to 0.03 wt% polyoxyethylene ether, and 0.02 wt% to 0.05 wt% sodium dodecyl sulfonate. The treatment temperature is 45℃ to 75℃, and the treatment time is 150 s to 400 s.

[0011] Furthermore, in the step of preparing the first intrinsic layer, the step of preparing the first amorphous phase layer includes: introducing a first silane, a first hydrogen gas and a first argon gas, and depositing the first amorphous phase layer; The steps for preparing the first crystalline phase layer include: introducing a second silane, a second hydrogen gas, and a second argon gas, and depositing the first crystalline phase layer.

[0012] Further, in the step of preparing the first amorphous phase layer, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of the first hydrogen to the first silane of 17.5:1 to 35:1, a flow ratio of the first argon to the first silane of 2:1 to 9:1, a temperature of 130℃ to 225℃, and a deposition time of 5 s to 18 s; and / or, In the step of preparing the first crystalline phase layer, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of the second hydrogen gas to the second silane of 12.5:1 to 25:1, a flow ratio of the second argon gas to the second silane of 1.5:1 to 7:1, a temperature of 130 to 225 °C, and a deposition time of 12 s to 32 s; and / or, The first silane and the second silane each comprise at least one of SiH4 and Si2H6; and / or, The pressure under the vacuum condition is 35 Pa to 255 Pa.

[0013] Thirdly, embodiments of this application provide a photovoltaic module, the photovoltaic module comprising the solar cell as described in the first aspect, or the photovoltaic module comprising the solar cell prepared by the preparation method of the second aspect.

[0014] Compared with the prior art, the beneficial effects of this application are as follows: This application improves the photoelectric performance of solar cells by adjusting the structure of the first intrinsic layer in the solar cell, thereby improving the epitaxial growth of the first intrinsic layer and reducing defects in the first doped conductive layer. Through the synergistic effect of these two aspects, the carrier lifetime is extended and the photoelectric performance of the solar cell is enhanced.

[0015] The first intrinsic layer of this application includes a first amorphous phase layer and a first crystalline phase layer, wherein the substrate is in direct contact with the first amorphous phase layer of the first intrinsic layer. That is, there is no epitaxial growth film layer between the substrate and the first amorphous phase layer with the zone axis orientation consistent with the substrate orientation. Such an anti-epitaxial structure setting can reduce the possibility of dangling bonds on the substrate surface being exposed, ensure the passivation effect of the first amorphous phase layer on the substrate surface defects, and improve the problem of carrier recombination.

[0016] Meanwhile, the first crystalline phase layer and the first doped conductive layer in the first intrinsic layer also have a close synergistic effect, playing a bidirectional optimization role for both. Specifically, a certain amount of hydrogen atoms are present during the formation of the first doped conductive layer. Since the surfaces of the first crystalline phase layer and the first doped conductive layer are in direct contact, the hydrogen atoms in the first doped conductive layer can combine with the interface state defects of the first crystalline phase layer, thus bringing two effects: First, for the first doped conductive layer, more hydrogen atoms combining with the interface state defects of the first crystalline phase layer means fewer hydrogen atoms combining with the doped atoms in the first doped conductive layer. This can reduce the content of complexes in the first doped conductive layer, improve the carrier recombination problem of the first doped conductive layer, and increase the effective doping amount of doped atoms in the first doped conductive layer; Second, for the first crystalline phase layer, since the interface state defects of the first crystalline phase layer can be effectively passivated, this is beneficial to improving the interface defects of the first crystalline phase layer, improving the contact performance between the first crystalline phase layer and the first doped conductive layer, and thus improving the carrier transport efficiency. Ultimately, the photoelectric performance of solar cells is improved by jointly improving the first doped conductive layer and the first crystalline phase layer. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the first type of solar cell provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the second type of solar cell provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the third type of solar cell provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the fourth type of solar cell provided in the embodiments of this application; Figure 5 This is a schematic diagram of the structure of the fifth type of solar cell provided in the embodiments of this application; Figure 6 This is a schematic diagram of the preparation method provided in the embodiments of this application; Figure 7 This is an HRTEM image of Embodiment 5 of this application; Figure 8 This is the HRTEM image of Comparative Example 1 of this application.

[0019] Explanation of reference numerals in the attached figures: 1. Substrate; 21. First intrinsic layer; 211. First amorphous phase layer; 212. First crystalline phase layer; 22. Second intrinsic layer; 221. Second amorphous phase layer; 222. Second crystalline phase layer; 31. First doped conductive layer; 32. Second doped conductive layer; 41. First transparent conductive layer; 42. Second transparent conductive layer; 51. First electrode; 52. Second electrode; 6. Antireflection layer; 7. Dielectric layer; 8. Passivation layer; 9. Epitaxial layer; A. Adsorbent. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In this application, 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 this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0022] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0023] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0024] 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.

[0025] When using crystalline silicon as the substrate for solar cells, the presence of dangling bonds on its surface increases surface defects, affecting carrier transport. Depositing a hydrogenated amorphous silicon layer on the crystalline silicon surface is one way to address this issue. Hydrogen within the hydrogenated amorphous silicon can combine with dangling bonds on the substrate surface to form silicon-hydrogen bonds, achieving both chemical passivation through the amorphous structure and field passivation through bandgap modulation. This reduces carrier recombination and improves carrier transport efficiency. However, the deposition of the amorphous silicon layer involves epitaxial growth, meaning the disordered amorphous silicon film is not in direct contact with the substrate; instead, a transition layer formed by epitaxial growth exists between the two layers. On the one hand, the transition film layer formed by epitaxial growth will form crystallization channels at the interface between the substrate and the amorphous silicon layer, causing the dangling bonds on the substrate surface to be re-exposed, resulting in an increase in defects and affecting carrier transport. On the other hand, epitaxial growth will also eliminate the wide bandgap characteristics of amorphous silicon, causing the amorphous silicon layer to lose its field passivation effect on carriers and increasing the recombination rate of carriers at the interface between the two film layers. Under the influence of the above two aspects, the effect on improving battery performance is limited.

[0026] Besides the impact of epitaxial growth on carrier transport, defects in the doped conductive layer can also exacerbate carrier recombination, reducing its transport efficiency. In the p-type doped conductive layer, p-type dopants and hydrogen atoms form complexes. On one hand, these complexes become centers of lattice distortion due to lattice mismatch, increasing carrier scattering and decreasing mobility. On the other hand, these complexes act as deep-level traps and centers of electron-hole recombination, accelerating nonradiative recombination of carriers, further reducing carrier concentration and transport efficiency, and affecting the photoelectric performance of the solar cell.

[0027] Based on in-depth research into the causes of the above-mentioned technical problems, this application provides a solar cell and its preparation method, as well as a photovoltaic module. By adjusting the structure of the first intrinsic layer in the solar cell, the epitaxial growth of the first intrinsic layer is improved while the defects of the first doped conductive layer are reduced. Under the synergistic effect of the two aspects, the carrier lifetime is extended and the photoelectric performance of the solar cell is improved.

[0028] The technical solutions provided in this application will be further described below with reference to the embodiments and accompanying drawings.

[0029] like Figure 1 As shown, this application embodiment provides a solar cell, which includes: The substrate 1 has a first surface and a second surface disposed opposite to each other; A first intrinsic layer 21 and a first doped conductive layer 31 are sequentially disposed on the first surface; wherein, along the direction from the substrate 1 to the first doped conductive layer 31, the first intrinsic layer 21 sequentially includes a first amorphous phase layer 211 and a first crystalline phase layer 212, the first amorphous phase layer 211 is in direct contact with the first surface of the substrate 1, and the first doped conductive layer 31 is in direct contact with the surface of the first crystalline phase layer 212. The doped atoms of the first doped conductive layer 31 include at least one of boron and gallium.

[0030] In this embodiment, one of the first and second surfaces is the light-receiving surface of substrate 1, and the other is the backlighting surface of substrate 1. For example, when substrate 1 is an N-type silicon substrate, as an optional implementation, the first surface is the light-receiving surface, i.e., the first intrinsic layer 21 and the first doped conductive layer 31 are disposed on the light-receiving side of the solar cell, and the PN junction is located on the light-receiving surface of substrate 1; as another optional implementation, the first surface is the backlighting surface, i.e., the first intrinsic layer 21 and the first doped conductive layer 31 are disposed on the backlighting side of the solar cell, and the PN junction is located on the backlighting surface of substrate 1. For example, when substrate 1 is a P-type silicon substrate, as an optional implementation, the first surface is the backlighting surface, i.e., the first intrinsic layer 21 and the first doped conductive layer 31 are disposed on the backlighting side of the solar cell, and the PN junction is located on the light-receiving surface of substrate 1; as another optional implementation, the first surface is the light-receiving surface, i.e., the first intrinsic layer 21 and the first doped conductive layer 31 are disposed on the light-receiving side of the solar cell, and the PN junction is located on the backlighting surface of substrate 1.

[0031] In this embodiment, the first intrinsic layer 21 includes a first amorphous phase layer 211 and a first crystalline phase layer 212. The solar cell includes a substrate 1 and the first amorphous phase layer 211, the first crystalline phase layer 212, and the first doped conductive layer 31 sequentially disposed thereon. This film layer configuration of the solar cell improves the epitaxial growth of the first intrinsic layer 21 near the substrate 1 while reducing defects in the first doped conductive layer 31. Through the synergistic effect of these two aspects, the carrier lifetime is extended, and the photoelectric performance of the solar cell is improved.

[0032] The first amorphous phase layer 211 is in direct contact with the substrate 1. This means there is no epitaxially grown transition film between the substrate 1 and the first amorphous phase layer 211 whose zone axis orientation aligns with that of the substrate 1. This structure ensures good bonding between the amorphous structure of the first amorphous phase layer 211 and the dangling bonds on the first surface of the substrate 1, achieving chemical passivation. It also enables field passivation through bandgap modulation of amorphous silicon, improving carrier transport efficiency at the interface between the substrate 1 and the first amorphous phase layer 211.

[0033] Meanwhile, the first crystalline phase layer 212 and the first doped conductive layer 31 are in direct contact, exhibiting a synergistic effect between the two layers. During the formation of the first doped conductive layer 31, a certain amount of hydrogen atoms are present. Due to the direct contact between the two layers, the hydrogen atoms in the first doped conductive layer 31 can combine with interface state defects (such as dangling bonds) in the first crystalline phase layer 212. This combination simultaneously optimizes both the first crystalline phase layer 212 and the first doped conductive layer 31—the defects in the first crystalline phase layer 212 are passivated by hydrogen atoms, resulting in better contact performance between the first crystalline phase layer 212 and the first doped conductive layer 31, thus improving the extraction and transport of charge carriers between the two layers. Furthermore, the reduction in the number of remaining hydrogen atoms in the first doped conductive layer 31 decreases the likelihood of them combining with dopant atoms (at least one of boron and gallium) to form complexes. Consequently, lattice distortion in the first doped conductive layer 31 is improved, and the number of deep-level traps and electron-hole recombination centers decreases, leading to increased charge carrier concentration and transport efficiency, thereby improving the photoelectric performance of the solar cell.

[0034] Preferably, the dopant atoms in the first doped conductive layer 31 are boron atoms.

[0035] Furthermore, the crystalline phases in the first crystalline phase layer 212 are discontinuously distributed along a plane perpendicular to the thickness direction of the solar cell. This discontinuous distribution means that the grains A within the crystalline phase exist isolated and dispersed in a specified direction, separated by amorphous phases or other defect regions, preventing the formation of a continuous crystalline phase spanning that direction. In this embodiment, the discontinuous distribution of the crystalline phases in the first crystalline phase layer 212 improves the doping effect of the first doped conductive layer 31 and enhances the photoelectric performance of the solar cell.

[0036] Further, the crystallinity of the first crystalline phase layer 212 is 20%~35%. The crystallinity is obtained by Raman spectroscopy. For example, the crystallinity of the first crystalline phase layer 212 is 20%, 25%, 30%, or 35%. In this embodiment, when the crystallinity of the first crystalline phase layer 212 is within the above range, the first crystalline phase layer 212 can reduce the content of boron-hydrogen complexes with the first doped conductive layer 31, reduce carrier recombination, better improve the doping effect of the first doped conductive layer 31, increase the carrier concentration of the first doped conductive layer 31, reduce the series resistance of the solar cell, increase the fill factor, and improve the photoelectric performance of the solar cell. Preferably, the crystallinity of the first crystalline phase layer 212 is 30%.

[0037] Furthermore, the doping concentration of the doped atoms in the first doped conductive layer 31 is 10. 16 pcs / cm 3 ~10 21 pcs / cm 3The doping concentration of the doped atoms was obtained through standard ECV testing using an electrochemical capacitance-voltage (ECV) meter. During the standard ECV test, the doping concentration at different locations was tested while the film was being etched. For example, the doping concentration of the doped atoms in the first doped conductive layer 31 was 10. 16 pcs / cm 3 10 18 pcs / cm 3 10 20 pcs / cm 3 Or 10 21 pcs / cm 3 In this embodiment, when the doping concentration of the doped atoms in the first doped conductive layer 31 is within the above-mentioned range, it is higher than the doping concentration of the P-type doped conductive layer in a conventional solar cell (10). 15 pcs / cm 3 Therefore, the carrier concentration in the first doped conductive layer 31 is higher, the series resistance of the solar cell is reduced, the fill factor is increased, and the photoelectric performance of the solar cell is improved.

[0038] Furthermore, base 1 <001> Zone axis orientation and the first crystal phase layer 212 <001> The zone axis orientations are different. Among them, <001> Zone axis orientation refers to the orientation of a zone axis under the Miller index specification, where the index is... <001> The direction of the normal vector of the crystallographic plane family.

[0039] Further, the thickness of the first amorphous phase layer 211 is 2.5 nm to 12.5 nm, and the thickness of the first crystalline phase layer 212 is 1 nm to 8 nm. The thickness of the film is obtained by ellipsometer measurement. For example, the thickness of the first amorphous phase layer 211 is 2.5 nm, 5 nm, 8 nm, 10 nm, or 12.5 nm, and the thickness of the first crystalline phase layer 212 is 1 nm, 4 nm, 6 nm, or 8 nm. In this embodiment, when the thickness of the first amorphous phase layer 211 is within the above range, microcrystalline silicon can be generated near the first crystalline phase layer 212, which is beneficial to the formation of the first crystalline phase layer 212; when the thickness of the first crystalline phase layer 212 is within the above range, a discontinuously distributed crystalline phase can be formed in the first crystalline phase layer 212, improving the film quality of the first doped conductive layer 31, reducing defects in the first doped conductive layer 31, improving the carrier transport performance, and also improving the problems of increased series resistance and increased parasitic absorption of solar cells caused by further increase in thickness, thereby improving the photoelectric performance of solar cells. Preferably, the thickness of the first amorphous phase layer 211 is 3 nm, and the thickness of the first crystalline phase layer 212 is 5 nm.

[0040] Optionally, the solar cell is a heterojunction cell (HJT), and its structural schematic diagram is shown below. Figure 1 and Figure 2As shown. The heterojunction solar cell further includes: a first transparent conductive layer 41 and a first electrode 51 sequentially disposed on the surface of the first doped conductive layer 31 facing away from the first intrinsic layer 21; and a second intrinsic layer 22, a second doped conductive layer 32, a second transparent conductive layer 42, and a second electrode 52 sequentially disposed on the second surface of the substrate 1. One of the first electrode 51 and the second electrode 52 is a positive electrode, and the other is a negative electrode. The doping atoms in the second doped conductive layer 32 include at least one of phosphorus, antimony, or arsenic.

[0041] Optionally, the solar cell is a heterojunction back contact cell (HBC), and its structural schematic diagram is shown below. Figure 3 and Figure 4 As shown. The heterojunction back contact battery further includes: a first transparent conductive layer 41 and a first electrode 51 sequentially disposed on the surface of the first doped conductive layer 31 facing away from the first intrinsic layer 21; a second intrinsic layer 22, a second doped conductive layer 32, a second transparent conductive layer 42, and a second electrode 52 sequentially disposed on the first surface of the substrate 1. The first intrinsic layer 21 and the second intrinsic layer 22 are disposed at intervals on the first surface of the substrate 1, and the first intrinsic layer 21 and the second intrinsic layer 22 are separated by an isolation region. The first surface is the backlight surface of the substrate 1, and the second surface is the light-receiving surface of the substrate 1. An antireflection layer 6 is also disposed on the light-receiving surface. The doped atoms in the second doped conductive layer 32 include at least one of phosphorus, antimony, or arsenic. One of the first electrode 51 and the second electrode 52 is a positive electrode, and the other is a negative electrode.

[0042] Optionally, the solar cell is a composite passivated back contact solar cell (HTBC or HPBC). The composite passivated back contact solar cell further includes: a first transparent conductive layer 41 and a first electrode 51 sequentially disposed on the surface of the first doped conductive layer 31 facing away from the first intrinsic layer 21; a dielectric layer 7, a second doped conductive layer 32, a second transparent conductive layer 42, and a second electrode 52 sequentially disposed on the first surface of the substrate 1; the dielectric layer 7 and the first intrinsic layer 21 are spaced apart on the first surface of the substrate 1, and are separated from the first intrinsic layer 21 by an isolation region. The first surface is the backlight surface of the substrate 1, and the second surface is the light-receiving surface of the substrate 1. The composite passivated back contact solar cell also includes a passivation layer 8 and an antireflection layer 6, which can be disposed only on the light-receiving surface (as shown in the schematic diagram). Figure 5 As shown, the second transparent conductive layer 42 can be disposed only between the second electrode 52 on the backlight surface, or it can be disposed simultaneously between the second transparent conductive layer 42 and the second electrode 52 on both the light-receiving surface and the backlight surface. The doped atoms in the second doped conductive layer 32 include at least one of phosphorus, antimony, or arsenic. One of the first electrode 51 and the second electrode 52 is a positive electrode, and the other is a negative electrode.

[0043] The first transparent conductive layer 41 and the second transparent conductive layer 42 are made of at least one of indium oxide, tin oxide, zinc oxide, indium tin oxide, indium zinc oxide, indium cerium oxide, or indium tungsten oxide. The first electrode 51 and the second electrode 52 are made of silver. The dielectric layer 7 is made of at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. The passivation layer 8 is made of aluminum oxide, and the antireflection layer 6 is made of one or more of silicon nitride, silicon oxynitride, or silicon oxide.

[0044] When the aforementioned heterojunction solar cell, heterojunction back contact solar cell, or composite passivated back contact solar cell includes the structure of substrate 1, first intrinsic layer 21, and first doped conductive layer 31 as described in this application, the carrier transport performance of the solar cell is improved, and the photoelectric performance is enhanced.

[0045] Furthermore, when the solar cell is a heterojunction cell or a heterojunction back-contact cell, along the direction from the substrate 1 to the second doped conductive layer 32, the second intrinsic layer 22 sequentially includes a second amorphous phase layer 221 and a second crystalline phase layer 222. When the solar cell is a heterojunction cell, the second amorphous phase layer 221 is in direct contact with the second surface of the substrate 1, and the second doped conductive layer 32 is in direct contact with the surface of the second crystalline phase layer 222. A schematic diagram of this structure is shown below. Figure 1 As shown in the diagram. When the solar cell is a heterojunction back-contact cell, the second amorphous phase layer 221 is in direct contact with the first surface of the substrate 1, and the second doped conductive layer 32 is in direct contact with the surface of the second crystalline phase layer 222. A schematic diagram of its structure is shown below. Figure 4 As shown. In this embodiment of the application, the second amorphous phase layer 221 in the substrate 1 and the second intrinsic layer 22 is in direct contact, that is, the epitaxial problem of the second intrinsic layer 22 near the substrate 1 is also improved, ensuring the passivation effect of the second intrinsic layer 22 on the surface of the substrate 1, reducing the attenuation of charge carriers, and further improving the photoelectric performance of the solar cell.

[0046] This application also provides a method for preparing the above-described solar cell. It is understood that this preparation method is one way to obtain the solar cell described in this application, but it is not limited to the only method. That is, the solar cell described in this application can also be prepared by other methods, and this application does not impose any limitations on this. Therefore, it should not be construed as a limitation on the solar cell provided in this application.

[0047] like Figure 6 As shown, the preparation method includes the following steps: The substrate 1 is wet-treated, the substrate 1 having a first surface and a second surface disposed opposite to each other, such that the first surface of the substrate 1 contains adsorbent A. Preparation of the first intrinsic layer 21: Under vacuum conditions, a first amorphous phase layer 211 and a first crystalline phase layer 212 are sequentially prepared on a first surface containing adsorbent A by chemical vapor deposition. During the preparation of the first amorphous phase layer 211 and the first crystalline phase layer 212, adsorbent A is removed and the first amorphous phase layer 211 is in direct contact with the substrate 1. A first doped conductive layer 31 is prepared on the surface of the first crystalline phase layer 212 that is opposite to the first amorphous phase layer 211. The doped atoms of the first doped conductive layer 31 include at least one of boron and gallium.

[0048] Among them, chemical vapor deposition methods include at least one of low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), or catalytic chemical vapor deposition (Cat-CVD).

[0049] The core issue in epitaxy of amorphous silicon layers on a substrate lies in the fact that during the formation of the amorphous silicon layer, the silicon atoms in the film are affected by the atoms on the substrate surface when deposited. Because the substrate is a crystalline silicon structure, the silicon atoms exhibit long-range ordered arrangement, resulting in periodic potential wells. When depositing an amorphous silicon thin film, the active molecules that first reach the substrate are trapped by these potential wells, inducing the film growth process and continuing the arrangement of the substrate lattice to form a locally ordered structure, i.e., the epitaxial layer.

[0050] In this embodiment, adsorbent A is adsorbed onto the surface of substrate 1 by force. Adsorbent A acts as a buffer during the preparation of the first amorphous phase layer 211 and is removed during the preparation of the first amorphous phase layer 211 and the first crystalline phase layer 212. Therefore, the first amorphous phase layer 211 and the first surface of substrate 1 are in direct contact, and there is no transition layer between the two layers. This reduces the influence of the crystalline structure of substrate 1 on the formation of the first amorphous phase layer 211, thus improving the epitaxiality problem and ensuring the passivation effect of the first amorphous phase layer 211 on substrate 1. At the same time, the step of preparing the first intrinsic layer 21 is carried out under vacuum conditions, and adsorbent A acting on the surface of substrate 1 by van der Waals forces is removed, avoiding adsorbent A residue at the interface between substrate 1 and the first amorphous phase layer 211, and ensuring the photoelectric performance of the solar cell. During the preparation of the first doped conductive layer 31, the interface state defects of the first crystalline phase layer 212 in the first intrinsic layer 21 combine with hydrogen atoms, which improves the recombination problem of charge carriers at the defects and reduces the content of complexes formed by doped atoms and hydrogen atoms in the first doped conductive layer 31, further improving the carrier transport efficiency. At the same time, it increases the effective doping of doped atoms and silicon atoms in the first doped conductive layer 31, increases the carrier concentration of the first doped conductive layer 31, reduces the series resistance of the solar cell, improves the fill factor, and improves the photoelectric performance of the solar cell.

[0051] Further, the vacuum pressure is 35 Pa to 255 Pa. Exemplarily, the vacuum pressure is 35 Pa, 100 Pa, 160 Pa, or 255 Pa. In this embodiment, when chemical vapor deposition is performed under vacuum conditions within the above pressure range, it can, on the one hand, prevent impurities in the air from entering the gas, thereby improving the quality of the film; on the other hand, it can enhance the diffusion and adsorption efficiency of the reactant gas, ensuring the density and uniformity of the film. Preferably, the pressure for preparing the first intrinsic layer 21 by chemical vapor deposition is 125 Pa to 210 Pa.

[0052] Further, the wet treatment step of substrate 1 includes: treating substrate 1 with a wet solution at 25℃~75℃ for 120 s~400 s and then rinsing with water. The wet solution includes a cleaning agent and an adsorbent A. The cleaning agent includes any one of hydrochloric acid-hydrogen peroxide mixed solution and hydrofluoric acid. The adsorbent A contains at least one of citrate, sulfonate, hydroxyl, ether, carboxylate, and acetate. The mass fraction of adsorbent A in the wet solution is 0.02%~0.7%.

[0053] Wherein, the mass fraction of adsorbent A in the wet solution refers to the ratio of the mass of adsorbent A to the mass of the wet solution. For example, the temperature of the wet solution treatment of substrate 1 is 25°C, 40°C, 55°C, or 75°C, the treatment time is 120 s, 200 s, 350 s, or 400 s, and the mass fraction of adsorbent A in the wet solution is 0.02 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, or 0.7 wt%.

[0054] In this embodiment, the cleaning agent in the wet solution removes the oxide layer on the surface of substrate 1. Then, substrate 1 is treated with adsorbent A containing citrate, sulfonate, hydroxyl, ether, carboxylate, or acetate groups. Adsorbent A adsorbs onto the first surface of substrate 1 via van der Waals forces. Afterward, water is used to wash away any residual cleaning agent and adsorbent A from the surface of substrate 1. The adsorption force of adsorbent A containing the aforementioned groups is neither too weak to be removed by water, ensuring the improvement of the surface energy of substrate 1, nor too strong to remain after the preparation of the first intrinsic layer 21, thus affecting the performance of the solar cell. At the aforementioned processing temperature and time, the removal effect of the cleaning agent on the oxide layer of substrate 1 and the adsorption effect of adsorbent A on substrate 1 are ensured, while avoiding the introduction of other defects into substrate 1. When the mass fraction of adsorbent A is within the aforementioned range, the buffering effect on the first amorphous phase layer 211 and the removal effect of adsorbent A are better balanced, further improving the performance of the solar cell.

[0055] Preferably, the temperature of the wet solution treatment of substrate 1 is 42℃~55℃, the treatment time is 180 s~300 s, and the mass fraction of adsorbent A in the wet solution is 0.06 wt%~0.4 wt%.

[0056] Furthermore, adsorbent A includes at least one of sodium citrate, sodium dodecyl sulfonate, ethylene glycol monobutyl ether, isopropanol, sodium benzoate, sodium acetate, polyoxyethylene ether, and sodium dodecyl sulfonate. In the embodiments of this application, adsorbent A contains at least one of citrate, sulfonate, hydroxyl, ether, carboxylate, and acetate groups, which can improve the surface energy of substrate 1 and can be removed after the subsequent preparation of the first intrinsic layer 21, ensuring the performance of the solar cell.

[0057] As an optional implementation method, the cleaning agent is a hydrochloric acid-hydrogen peroxide mixed solution. The wet solution includes 5 wt%~10 wt% hydrochloric acid, 5 wt%~7.5 wt% hydrogen peroxide, 0.10 wt%~0.16 wt% sodium citrate, 0.04 wt%~0.06 wt% sodium dodecyl sulfonate, 0.04 wt%~0.16 wt% ethylene glycol monobutyl ether, and 0.15 wt%~0.30 wt% isopropanol. The treatment temperature is 20℃~50℃, and the treatment time is 120 s~310 s.

[0058] Wherein, the mass fraction of each substance is the ratio of the mass of each substance to the mass of the wet process solution. For example, when the wet process solution is composed of the above raw materials, the mass fraction of hydrochloric acid is 5 wt%, 8 wt%, or 10 wt%, the mass fraction of hydrogen peroxide is 5 wt%, 6 wt%, or 7.5 wt%, the mass fraction of sodium citrate is 0.10 wt%, 0.13 wt%, or 0.16 wt%, the mass fraction of sodium dodecyl sulfonate is 0.04 wt%, 0.05 wt%, or 0.06 wt%, the mass fraction of ethylene glycol monobutyl ether is 0.04 wt%, 0.10 wt%, or 0.16 wt%, the mass fraction of isopropanol is 0.15 wt%, 0.22 wt%, or 0.30 wt%, the processing temperature is 20℃, 30℃, 40℃, or 50℃, and the processing time is 120 s, 180 s, 260 s, or 310 s. In this embodiment, the cleaning agent composed of hydrochloric acid and hydrogen peroxide can effectively oxidize the oxides on the surface of the substrate 1, reducing the oxygen content on the surface of the substrate 1. Simultaneously, it ensures the uniformity of the substrate 1 surface, allowing the subsequent adsorbent A to have a good adsorption effect on the silicon substrate 1 surface, reducing deposition-induced sites. Therefore, during the preparation of the first amorphous phase layer 211, epitaxial problems do not occur, improving the passivation effect of the first amorphous phase layer 211 on the substrate 1 and enhancing the carrier transport efficiency. Preferably, the wet solution comprises 10 wt% hydrochloric acid, 5 wt% hydrogen peroxide, 0.10 wt% sodium citrate, 0.04 wt% sodium dodecyl sulfonate, 0.04 wt% ethylene glycol monobutyl ether, and 0.15 wt% isopropanol. The processing temperature is 35℃~45℃, and the processing time is 180 s~270 s.

[0059] As another optional implementation method, the cleaning agent is hydrofluoric acid, and the wet solution includes 2 wt%~8 wt% hydrofluoric acid, 0.01 wt%~0.03 wt% sodium benzoate, 0.02 wt%~0.04 wt% sodium acetate, 0.01 wt%~0.03 wt% polyoxyethylene ether, and 0.02 wt%~0.05 wt% sodium dodecyl sulfonate. The treatment temperature is 45℃~75℃, and the treatment time is 150 s~400 s.

[0060] For example, when the wet solution is composed of the above-mentioned raw materials, the mass fraction of hydrofluoric acid is 2 wt%, 5 wt%, or 8 wt%, the mass fraction of sodium benzoate is 0.01 wt%, 0.02 wt%, or 0.03 wt%, the mass fraction of sodium acetate is 0.02 wt%, 0.03 wt%, or 0.04 wt%, the mass fraction of polyoxyethylene ether is 0.01 wt%, 0.02 wt%, or 0.03 wt%, the mass fraction of sodium dodecyl sulfonate is 0.02 wt%, 0.03 wt%, 0.04 wt%, or 0.05 wt%, the processing temperature is 45°C, 55°C, 65°C, or 75°C, and the processing time is 150 s, 230 s, 310 s, or 400 s. In this embodiment, hydrofluoric acid, as a cleaning agent, can reduce oxides on the surface of substrate 1, thereby reducing the oxygen content on the surface of substrate 1 and ensuring the uniformity of the substrate surface. This improves the adsorption effect of adsorbent A on the surface of the silicon substrate 1, thus achieving the purpose of preventing epitaxy during the preparation of the first amorphous phase layer 211, improving the passivation effect of the first amorphous phase layer 211 on substrate 1, and enhancing the carrier transport efficiency. Preferably, the wet solution includes 3 wt% hydrofluoric acid, 0.01 wt% sodium benzoate, 0.02 wt% sodium acetate, 0.01 wt% of the aforementioned polyoxyethylene ether, and 0.02 wt% sodium dodecyl sulfonate. The processing temperature is 45℃~65℃, and the processing time is 200 s~300 s.

[0061] Further, the step of preparing the first amorphous phase layer 211 includes: introducing a first silane, a first hydrogen gas, and a first argon gas to deposit the first amorphous phase layer 211. The first silane includes at least one of SiH4 and Si2H6. In this embodiment, during the preparation of the first amorphous phase layer 211, under vacuum conditions, the active material generated by the first silane is buffered by the adsorbent A layer on the first surface of the substrate 1. Therefore, the formation of the film layer 211 near the substrate 1 is not affected by the crystal structure of the substrate 1, i.e., no epitaxial problem occurs. Simultaneously, as the preparation of the first amorphous phase layer 211 is carried out under vacuum conditions, the adsorbent A acting on the surface of the substrate 1 by van der Waals forces is removed, preventing adsorbent A from remaining in the solar cell and affecting its photoelectric performance.

[0062] Further, in the step of preparing the first amorphous phase layer 211, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of first hydrogen to first silane of 17.5:1 to 35:1, a flow ratio of first argon to first silane of 2:1 to 9:1, a temperature of 130℃ to 225℃, and a deposition time of 5 s to 18 s. Exemplarily, the radio frequency is 2 MHz, 13 MHz, 26 MHz, 31 MHz, or 40 MHz, the flow ratio of first hydrogen to first silane is 17.5:1, 22:1, 28:1, or 35:1, and the flow ratio of first argon to first silane is 2:1, 5:1, or 9:1. In this embodiment, epitaxial growth is prevented by adsorbing adsorbent A onto the first surface through wet processing, rather than by increasing the hydrogen dilution ratio (i.e., the flow ratio of the first hydrogen to the first silane). Therefore, the hydrogen dilution ratio in this application is lower, which can increase the formation rate of the first amorphous phase layer 211 without affecting the film properties. Simultaneously, due to the process parameters and time for preparing the first amorphous phase layer 211, microcrystalline silicon is generated on the side of the first amorphous phase layer 211 close to the first crystalline phase layer 212, which is beneficial to the formation of the first crystalline phase layer 212. Preferably, in the step of preparing the first amorphous phase layer 211, the radio frequency is 13 MHz to 26 MHz, the flow ratio of the first hydrogen to the first silane is 18:1 to 22:1, the flow ratio of the first argon to the first silane is 4:1 to 6:1, the substrate temperature is 180℃ to 210℃, and the deposition time is 8 s to 12 s.

[0063] Further, the step of preparing the first crystalline phase layer 212 includes: introducing a second silane, a second hydrogen gas, and a second argon gas to deposit the first crystalline phase layer 212. The second silane includes at least one of SiH4 and Si2H6.

[0064] Further, in the step of preparing the first crystalline phase layer 212, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of second hydrogen to second silane of 12.5:1 to 25:1, a flow ratio of second argon to second silane of 1.5:1 to 7:1, a temperature of 130 to 225°C, and a deposition time of 12 to 32 s; exemplary, the radio frequency is 2 MHz, 13 MHz, 26 MHz, 31 MHz or 40 MHz, the flow ratio of second hydrogen to second silane is 12.5:1, 18:1, 21:1 or 25:1, and the flow ratio of second argon to second silane is 1.5:1, 4:1 or 7:1. In this embodiment, under the aforementioned raw material flow ratio and time conditions, a first crystalline phase layer 212 can be formed, and the crystalline phases in the first crystalline phase layer 212 are discontinuously distributed along a plane perpendicular to the thickness direction of the solar cell. This reduces defects in the first doped conductive layer 31, improves carrier transport efficiency, and simultaneously enhances the effective doping of the first doped conductive layer 31, thereby improving the photoelectric performance of the solar cell. Preferably, in the step of preparing the first crystalline phase layer 212, the radio frequency is 13 MHz to 26 MHz, the flow ratio of the second hydrogen gas to the second silane is 18:1 to 22:1, the flow ratio of the second argon gas to the second silane is 4:1 to 6:1, the substrate temperature is 180℃ to 210℃, and the deposition time is 10 s to 15 s.

[0065] Further, the step of preparing the first doped conductive layer 31 includes: introducing a third silane, a gas source containing doped atoms, a third hydrogen gas, and a third argon gas, and depositing the first doped conductive layer 31. The third silane includes at least one of SiH4 and Si2H6, and the gas source containing doped atoms includes at least one of boron trichloride and borane. In this embodiment, during the preparation of the doped conductive layer on the surface of the first crystalline phase layer 212, the active material (hydrogen atoms) generated by the third silane will also generate hydrogen atoms when the gas source containing doped atoms is borane. The dangling bonds on the surface of the first crystalline phase layer 212 away from the first amorphous phase layer 211 can capture hydrogen atoms and form silicon-hydrogen bonds, reducing the combination of doped atoms and hydrogen atoms in the first doped conductive layer 31, improving the effective doping of the first doped conductive layer 31, improving the carrier transport performance in the first doped conductive layer 31, and improving the photoelectric performance of the solar cell.

[0066] Furthermore, after the step of preparing the first doped conductive layer 31, other preparation steps are also included: When the solar cell is a heterojunction cell or a heterojunction back-contact cell, the fabrication method further includes fabricating a second intrinsic layer 22, fabricating a second doped conductive layer 32, fabricating a transparent conductive layer (including a first transparent conductive layer 41 and a second transparent conductive layer 42), and fabricating electrodes (including a first electrode 51 and a second electrode 52). The second intrinsic layer 22 can be fabricated using conventional methods or the same method as the first intrinsic layer 21 of this application, i.e., forming an adsorption layer on the second surface of the substrate 1, followed by forming a second amorphous phase layer 221 in direct contact with the substrate 1, and then a second crystalline phase layer 222 disposed on the surface of the second amorphous phase layer 221 away from the substrate 1. Preferably, the second intrinsic layer 22 is fabricated using the same method as the first intrinsic layer 21 of this application. In this case, the epitaxiality problem of the second intrinsic layer 22 near the substrate 1 is also improved, ensuring the passivation effect of the second intrinsic layer 22 on the surface of the substrate 1, reducing carrier attenuation, and further improving the photoelectric performance of the solar cell. This application does not limit the fabrication methods of other films.

[0067] When the solar cell is a composite passivated back contact solar cell, the fabrication method further includes fabricating a dielectric layer 7, a second intrinsic layer 22, a second doped conductive layer 32, a passivation layer 8, an antireflection layer 6, a transparent conductive layer (including a first transparent conductive layer 41 and a second transparent conductive layer 42), and electrodes (including a first electrode 51 and a second electrode 52). This application does not limit the fabrication methods of other films.

[0068] This application also provides a photovoltaic module. The photovoltaic module includes the solar cell described above, or includes a solar cell prepared by the above method.

[0069] The technical solution of this application will be further explained below with reference to more specific embodiments and experimental test results.

[0070] Example 1 This embodiment provides a heterojunction solar cell, the preparation method of which includes: Step 1: Wet treatment Provides an N-type silicon substrate, which has a light-receiving side and a back-lighting side; The light-receiving and back-light-receiving surfaces of an N-type silicon substrate are treated with a wet solution at 42°C for 180 s each, followed by rinsing with water, or the first and second surfaces contain adsorbents. The cleaning agents in the wet solution are hydrochloric acid (X1=10 wt%), hydrogen peroxide (X2=5 wt%), and the adsorbents are sodium citrate (Y1=0.10 wt%), sodium dodecyl sulfonate (Y2=0.04 wt%), ethylene glycol monobutyl ether (Y3=0.04 wt%), and isopropanol (Y4=0.15 wt%).

[0071] Step 2: Prepare the first intrinsic layer and the second intrinsic layer Plasma-enhanced chemical vapor deposition was used at 210 Pa and 13.56 MHz radio frequency. In step two, the flow ratio of H2 to SiH4 in silane was 20:1, and the flow ratio of Ar to SiH4 was 5:1. A first amorphous silicon layer was deposited on the backlight side, and a second amorphous silicon layer was deposited on the light-receiving side. The temperature was 210℃, and the deposition time was 10 s. The thicknesses of the first and second amorphous silicon layers were 3 nm, respectively.

[0072] Then, under the same process conditions, namely 210 Pa and 13.56 MHz RF, the flow ratio of H2 to SiH4 in silane in step two is 20:1, and the flow ratio of Ar to SiH4 is 5:1. A first crystalline silicon layer is deposited on the surface of the first amorphous silicon layer away from the N-type silicon substrate, and a second amorphous silicon layer is deposited on the second surface at a temperature of 210°C for 15 s. The thicknesses of the first crystalline silicon layer and the second crystalline silicon layer are 5 nm, respectively.

[0073] Step 3: Fabrication of the first doped conductive layer and the second doped conductive layer A boron-doped layer with a thickness of 30 nm is prepared on the surface of the first crystalline silicon layer away from the N-type silicon substrate as the first doped conductive layer, and a phosphorus-doped layer with a thickness of 20 nm is prepared on the surface of the second crystalline silicon layer away from the N-type silicon substrate as the second doped conductive layer.

[0074] Step 4: Fabrication of the first transparent conductive layer and the second transparent conductive layer An indium tin oxide layer with a thickness of 100 nm was prepared as the first transparent conductive layer, and an indium tin oxide layer with a thickness of 100 nm was prepared as the second transparent conductive layer.

[0075] Step 5: Fabrication of the first and second electrodes A copper grid line with a thickness of 12 μm was prepared as the first electrode, and a copper grid line with a thickness of 9 μm was prepared as the second electrode.

[0076] The only difference between Examples 2-4 and Example 1 is the process parameters in step 1. The parameters for Examples 1-4 are shown in Table 1. Here, Y represents the total mass fraction of the adsorbent, i.e., Y = Y1 + Y2 + Y3 + Y4.

[0077] Table 1. Process parameters for Examples 1 to 4

[0078] Note: " / " indicates that no test data exists.

[0079] Example 5 The only difference between this embodiment and Example 1 is that in the wet solution formulation of step one, the cleaning agent is hydrofluoric acid (X=3 wt%), the adsorbent is sodium benzoate (Y1=0.01 wt%), sodium acetate (Y2=0.02 wt%), polyoxyethylene ether (Y3=0.01 wt%), and sodium dodecyl sulfonate (Y4=0.02 wt%), the treatment time is 200 s, and the treatment temperature is 55℃.

[0080] The only difference between Examples 6-9 and Example 5 is the process parameters in step 1. The parameters for Examples 5-9 are shown in Table 2. Here, Y represents the total mass fraction of the adsorbent, i.e., Y = Y1 + Y2 + Y3 + Y4.

[0081] Table 2. Process parameters for Examples 5 to 9

[0082] Example 10 The only difference between this embodiment and Embodiment 5 is that the deposition time for the first and second silicon layers in step two is 18 seconds. The thickness of the first silicon layer is 6 nm, and the thickness of the second silicon layer is 6 nm. The crystalline phases in the first and second crystalline phase layers are continuously distributed along a plane perpendicular to the thickness direction of the solar cell.

[0083] Comparative Example 1 The preparation method in this comparative example does not include step one. A first intrinsic layer and a second intrinsic layer are directly deposited on the surface of an N-type silicon substrate for 25 seconds. Other process parameters are the same as in Example 1. The first and second intrinsic layers are single-layer films with a thickness of 8 nm each. Subsequent preparation methods are the same as steps 3-5 in Example 1. A crystalline phase structure exists between the amorphous phase structure in the first and second intrinsic layers and the substrate as a transition.

[0084] Comparative Example 2 The preparation method in this comparative example does not include step one. A first intrinsic layer and a second intrinsic layer are directly deposited on the surface of an N-type silicon substrate. The preparation of both the first and second intrinsic layers is divided into two stages. In the first stage, the flow ratio of silane (H2:SiH4) is 38:1, the flow ratio of Ar to SiH4 is 7:1, the pressure is 125 Pa, the temperature is 210°C, and the deposition time is 18 s, resulting in a film thickness of 3 nm. In the second stage, the flow ratio of silane (H2:SiH4) is 20:1, the flow ratio of Ar to SiH4 is 5:1, the temperature is 210°C, and the deposition time is 15 s, resulting in a film thickness of 5 nm. Subsequent preparation methods are the same as steps 3 to 5 in Example 1. A crystalline phase structure exists between the amorphous phase structure in the first and second intrinsic layers and the substrate as a transition.

[0085] Performance testing 1. Crystallinity The N-type silicon substrates of Examples 1, 5, and 8-10 were replaced with glass monolayers. After wet processing of the glass monolayers, a first intrinsic layer and a second intrinsic layer were prepared on their surface. The first crystalline silicon layer of Examples 1, 5, and 8-10 was then tested using a Raman spectrometer. The wet processing process and the process for preparing the first and second intrinsic layers were the same as those in Example 1.

[0086] The N-type silicon substrate of Comparative Example 1 was replaced with a glass monolayer, and a first intrinsic layer and a second intrinsic layer were prepared on its surface. The first intrinsic layer was then tested using a Raman spectrometer.

[0087] The N-type silicon substrate of Comparative Example 2 was replaced with a glass monolayer. After a first intrinsic layer and a second intrinsic layer were prepared on its surface, the film layer formed by the second stage deposition in the first intrinsic layer was tested using a Raman spectrometer.

[0088] The results of the crystallinity test are shown in Table 3.

[0089] 2. Doping concentration of doped atoms in the first doped conductive layer The first doped conductive layer of the heterojunction solar cells of Examples 1, 5, 8-10, and Comparative Examples 1-2 was tested using an electrochemical capacitance-voltage tester. The test results are shown in Table 3.

[0090] 3. Film thickness test Examples 1 to 10 were tested using an ellipsometry.

[0091] 4. Lattice fringe image test High-resolution transmission electron microscopy was used to test the solar cells of Example 5 and Comparative Example 1. The test results of the substrate, first intrinsic layer, and first doped layer regions of Example 5 are as follows: Figure 7 As shown, the test results for the substrate, first intrinsic layer, and first doped layer regions of Comparative Example 1 are as follows: Figure 8 As shown. By Figure 7 and Figure 8 It can be seen that in Example 5, the amorphous silicon layer in the first intrinsic layer is in direct contact with the substrate, while in Comparative Example 1, an epitaxial layer exists between the amorphous phase layer and the substrate. Furthermore, in Example 5, the lattice fringes of the first crystalline silicon layer and the substrate are arranged differently, therefore the substrate… <001> Zone axis orientation and the first crystal phase layer <001> The zone axis orientations are different.

[0092] 5. Photoelectric properties The solar cells from Examples 1-10 and Comparative Examples 1-2 were subjected to performance tests using a Halm testing and sorting equipment, including open-circuit voltage, fill factor, and photoelectric conversion efficiency. The Halm equipment simulates sunlight and is equipped with electronic loads, data acquisition and calculation devices to test the electrical performance of photovoltaic devices (including solar cells). The calibrated light intensity of the solar cells under test was controlled at 1000 ± 5 W / m². 2 The test results are shown in Table 4.

[0093] Table 3. Test results of performance tests 1 to 2 for Examples 1 to 10 and Comparative Examples 1 to 2.

[0094] Table 4. Photoelectric performance test results of Examples 1-10 and Comparative Examples 1-2

[0095] The structures in Examples 1-10 where the crystalline silicon layer is in direct contact with the substrate, combined with... Figure 7 As shown in Tables 3 and 4, in Examples 1 to 10, the amorphous silicon layer in the first intrinsic layer and the second intrinsic layer is in direct contact with the substrate, thus providing better passivation of surface defects and higher carrier transport efficiency at the interface between the substrate and the amorphous phase layer. Compared with Comparative Examples 1 and 2, Examples 1 to 10 of this application have higher crystallinity. Therefore, the first crystalline silicon layer of this application can better reduce the formation of boron-oxygen complexes in the first doped conductive layer, resulting in a higher doping concentration of doped atoms in the first doped conductive layer, improving carrier transport efficiency, and ultimately improving the fill factor and photoelectric conversion efficiency of the solar cell.

[0096] By comparing Example 5 and Example 10, it can be seen that Example 5 has better photoelectric performance. This is mainly because the crystal phase in Example 5 is discontinuous, which is conducive to further increasing the doping concentration of the first doped conductive layer, resulting in higher carrier transport efficiency and better photoelectric performance of the solar cell.

[0097] By comparing Examples 1 to 4 with Examples 5 to 10, it can be seen that the wet solution using hydrofluoric acid as the cleaning agent and sodium benzoate, sodium acetate, polyoxyethylene ether, and sodium dodecyl sulfonate as adsorbents has a better passivation effect on the substrate and the photovoltaic performance of the solar cell is more excellent.

[0098] Comparing Examples 1 and 4 reveals that, since the cleaning agent also includes hydrogen peroxide, the hydrogen peroxide can further enhance the oxidative etching of the substrate surface oxides by the cleaning agent, improve the adsorption effect of the adsorbent, and thus improve the passivation effect of the first and second amorphous silicon layers on the substrate. Comparing Examples 1 and 3 reveals that, using a hydrochloric acid-hydrogen peroxide mixed solution as the cleaning agent and sodium citrate, sodium dodecyl sulfonate, ethylene glycol monobutyl ether, and isopropanol as the adsorbents in a wet treatment solution, when the substrate is wet-treated at 20°C to 50°C for 120 s to 310 s, the passivation effect on the substrate can be guaranteed while avoiding over-treatment that could introduce other defects to the substrate, thereby improving the photoelectric performance of the positron. Comparing Examples 5 and 7-9, it can be seen that the wet solution using hydrofluoric acid as the cleaning agent and sodium benzoate, sodium acetate, polyoxyethylene ether, and sodium dodecyl sulfonate as adsorbents has a better passivation effect on substrate defects and results in superior photoelectric performance of the solar cell when the substrate is wet-treated at 45°C to 75°C for 150 s to 400 s.

[0099] The technical solutions disclosed in the embodiments of this application have been described in detail above. Specific examples have been used in this article 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 technical solutions and core inventive points of the embodiments of this application. 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 application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A solar cell, characterized by, The solar cell includes: The substrate has a first surface and a second surface disposed opposite to each other; A first intrinsic layer and a first doped conductive layer are sequentially disposed on the first surface; wherein, along the direction from the substrate to the first doped conductive layer, the first intrinsic layer sequentially includes a first amorphous phase layer and a first crystalline phase layer, the first amorphous phase layer is in direct contact with the first surface of the substrate, and the first doped conductive layer is in direct contact with the surface of the first crystalline phase layer; The doping atoms of the first doped conductive layer include at least one of boron and gallium.

2. The solar cell according to claim 1, characterized in that, The crystalline phases in the first crystalline phase layer are discontinuously distributed along a plane perpendicular to the thickness direction of the solar cell; and / or, The crystallinity of the first crystalline phase layer is 20%~35%; and / or, a dopant concentration of the dopant atoms in the first doped conductive layer is 10 16 cm 3 -10 21 cm 3 ; and / or, The substrate <001> Zone axis orientation and the first crystal phase layer <001> Different zone axis orientations; and / or, The thickness of the first amorphous phase layer is 2.5 nm to 12.5 nm, and the thickness of the first crystalline phase layer is 1 nm to 8 nm.

3. Solar cell according to any of claims 1-2, characterized in that, The solar cell is a heterojunction cell, further comprising: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer opposite to the first intrinsic layer; a second intrinsic layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the second surface of the substrate, wherein one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode, and the doping atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic; or, The solar cell is a heterojunction back-contact cell, further comprising: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer facing away from the first intrinsic layer; a second intrinsic layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the first surface of the substrate, wherein the first intrinsic layer and the second intrinsic layer are spaced apart on the first surface of the substrate and separated by an isolation region; the doping atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic, wherein one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode; or, The solar cell is a composite passivated back contact solar cell, which further includes: a first transparent conductive layer and a first electrode sequentially disposed on the surface of the first doped conductive layer facing away from the first intrinsic layer; a dielectric layer, a second doped conductive layer, a second transparent conductive layer, and a second electrode sequentially disposed on the first surface of the substrate; the dielectric layer and the first intrinsic layer are disposed on the first surface of the substrate at a distance, and the dielectric layer and the first intrinsic layer are separated by an isolation region; the doped atoms in the second doped conductive layer include at least one of phosphorus, antimony, or arsenic, and one of the first electrode and the second electrode is a positive electrode and the other is a negative electrode.

4. A method for producing a solar cell, characterized by The preparation method includes: A wet-processed substrate has a first surface and a second surface disposed opposite to each other, such that an adsorbent is present on the first surface of the substrate; Preparation of the first intrinsic layer: Under vacuum conditions, a first amorphous phase layer and a first crystalline phase layer are sequentially prepared on the first surface where the adsorbent is present by chemical vapor deposition, and the adsorbent is removed during the preparation of the first amorphous phase layer and the first crystalline phase layer, and the first amorphous phase layer is in direct contact with the substrate. A first doped conductive layer is prepared on the surface of the first crystalline phase layer opposite to the first amorphous phase layer, wherein the doping atoms of the first doped conductive layer include at least one of boron and gallium.

5. The preparation method according to claim 4, characterized in that, The wet treatment step of the substrate includes: treating the substrate with a wet solution at 25℃~75℃ for 120 s~400 s and then rinsing with water. The wet solution includes a cleaning agent and the adsorbent. The cleaning agent includes any one of hydrochloric acid-hydrogen peroxide mixed solution and hydrofluoric acid. The adsorbent contains at least one of citrate, sulfonate, hydroxyl, ether, carboxylate, and acetate. The mass fraction of the adsorbent in the wet solution is 0.02 wt%~0.7 wt%.

6. The preparation method according to claim 5, characterized in that, The adsorbent includes at least one of sodium citrate, sodium dodecyl sulfonate, ethylene glycol monobutyl ether, isopropanol, sodium benzoate, sodium acetate, polyoxyethylene ether, and sodium dodecyl sulfonate.

7. The preparation method according to claim 6, characterized in that, In the step of wet substrate treatment, the cleaning agent is the hydrochloric acid-hydrogen peroxide mixed solution. The wet solution comprises 5 wt%~10 wt% hydrochloric acid, 5 wt%~7.5 wt% hydrogen peroxide, 0.10 wt%~0.16 wt% sodium citrate, 0.04 wt%~0.06 wt% sodium dodecyl sulfonate, 0.04 wt%~0.16 wt% ethylene glycol monobutyl ether, and 0.15 wt%~0.30 wt% isopropanol. The treatment temperature is 20℃~50℃, and the treatment time is 120 s~310 s; or... The cleaning agent is hydrofluoric acid, and the wet solution comprises 2 wt% to 8 wt% hydrofluoric acid, 0.01 wt% to 0.03 wt% sodium benzoate, 0.02 wt% to 0.04 wt% sodium acetate, 0.01 wt% to 0.03 wt% polyoxyethylene ether, and 0.02 wt% to 0.05 wt% sodium dodecyl sulfonate. The treatment temperature is 45℃ to 75℃, and the treatment time is 150 s to 400 s.

8. The preparation method according to claim 4, characterized in that, In the step of preparing the first intrinsic layer, the step of preparing the first amorphous phase layer includes: introducing first silane, first hydrogen and first argon to deposit the first amorphous phase layer; The steps for preparing the first crystalline phase layer include: introducing a second silane, a second hydrogen gas, and a second argon gas, and depositing the first crystalline phase layer.

9. The preparation method according to claim 8, characterized in that, In the step of preparing the first amorphous phase layer, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of the first hydrogen to the first silane of 17.5:1 to 35:1, a flow ratio of the first argon to the first silane of 2:1 to 9:1, a temperature of 130℃ to 225℃, and a deposition time of 5 s to 18 s; and / or, In the step of preparing the first crystalline phase layer, plasma-enhanced chemical vapor deposition is used, with a radio frequency of 2 MHz to 40 MHz, a flow ratio of the second hydrogen to the second silane of 12.5:1 to 25:1, a flow ratio of the second argon to the second silane of 1.5:1 to 7:1, a temperature of 130 to 225 °C, and a deposition time of 12 s to 32 s; and / or, The first silane and the second silane each comprise at least one of SiH4 and Si2H6; and / or, The pressure under the vacuum condition is 35 Pa to 255 Pa.

10. A photovoltaic module, characterized in that, The photovoltaic module includes a solar cell as described in any one of claims 1-3 or a solar cell prepared by the preparation method described in any one of claims 4-9.

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