A back contact solar cell and a method of manufacturing

Abstract

The present disclosure relates to the technical field of solar cells, and discloses a back contact solar cell and a preparation method. The back contact solar cell of the present disclosure comprises a back light surface of a base layer, which comprises first regions and second regions arranged alternately; a first passivation contact structure of the first regions comprises a tunneling oxide layer and a doped polysilicon layer; a second passivation contact structure of the second regions comprises a first structure layer and a second structure layer; the first structure layer comprises a first contact region with an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer and a first non-contact region with an intrinsic amorphous silicon layer; the second structure layer comprises a second contact region with a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer and a second non-contact region with a doped amorphous silicon layer, the first contact region and the second contact region at least partially overlap and cover part of the second regions; a first electrode is connected to the doped polysilicon layer, and a second electrode is connected to the second contact region, thereby optimizing the characteristic matching of different regions and improving the power generation performance of the cell.

Description

Technical Field

[0001] This disclosure relates to the field of solar cell technology, specifically to a back-contact solar cell and its fabrication method. Background Technology

[0002] Back-contact solar cells (BC cells) are a type of solar cell where both the positive and negative electrodes are located on the back of the cell. With no grid lines obstructing the front, they effectively improve light absorption efficiency and reduce current loss. With the continuous development of solar cell technology, hybrid back-contact solar cells, which combine back-contact technology with other cell technologies, have attracted widespread attention. For example, the tunneling oxide passivated contact solar cell (TOPCon cell) and BC cell technologies, forming the tunneling oxide passivated back-contact solar cell (TBC cell), apply the tunneling oxide layer and polycrystalline silicon doped passivation contact structure of the TOPCon cell to the back-contact cell. All electrodes are fabricated on the back of the cell, retaining the high current advantage of the BC cell on the front while further improving the open-circuit voltage and photoelectric conversion efficiency.

[0003] In back-contact solar cells, the performance of the doped layer directly determines the photoelectric conversion efficiency, especially in TBC cells. P-type doped layers (p-poly) are weaker than n-type doped layers (n-poly) in both passivation and contact performance, yet significant optimization in their manufacturing processes is difficult. Therefore, the industry has begun to use heterojunction passivation contact technology with intrinsic amorphous silicon / p-type doped amorphous silicon to replace traditional p-type passivation contact structures, thus forming hybrid passivated back-contact solar cells. However, the specific structure and fabrication process of this hybrid integrated cell based on TOPCon and heterojunction cell forms are not yet mature, and the overall performance and photoelectric conversion efficiency of the cells still need to be optimized and improved. Summary of the Invention

[0004] In view of this, the present disclosure provides a back-contact solar cell and a method for its fabrication, in order to solve the problems of poor performance and photoelectric conversion efficiency of existing back-contact solar cells.

[0005] In a first aspect, this disclosure provides a back-contact solar cell, comprising: a substrate layer, a first passivation contact structure, a second passivation contact structure, a first electrode, and a second electrode. The substrate layer includes a light-receiving surface and a back-lighting surface disposed opposite to each other, and the back-lighting surface includes alternating first and second regions. The first passivation contact structure is located in the first region and includes a tunneling oxide layer and a doped polycrystalline silicon layer stacked together, with the tunneling oxide layer disposed relatively close to the back-lighting surface. The second passivation contact structure is located at least in the second region and includes a first structural layer and a second structural layer stacked together, with the first structural layer disposed relatively close to the back-lighting surface. The first structural layer includes an adjacent first contact region and a first non-contact region, the first contact region including an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the first non-contact region including an intrinsic amorphous silicon layer. The second structural layer includes an adjacent second contact region and a second non-contact region, the second contact region including a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, and the second non-contact region including a doped amorphous silicon layer. The first contact region and the second contact region at least partially overlap and cover a portion of the second region. The first electrode is connected to the doped polycrystalline silicon layer, and the second electrode is connected to the second contact region.

[0006] In one optional implementation, the width of the first contact area is greater than or equal to the width of the second electrode and less than or equal to the width of the second region; the width of the second contact area is greater than or equal to the width of the second electrode and less than or equal to the width of the second region.

[0007] In one alternative embodiment, in the second structural layer, the crystallinity of the second contact region is greater than that of the second non-contact region, or the carrier mobility of the second contact region is greater than that of the second non-contact region, or the conductivity of the second contact region is greater than that of the second non-contact region.

[0008] In one optional embodiment, the crystallinity of the doped microcrystalline silicon layer ranges from 30% to 80%, and the crystallinity of the doped amorphous silicon layer is less than 30%; or the carrier mobility of the doped microcrystalline silicon layer ranges from 10. -1 ~10 0 cm 2 The carrier mobility of the doped amorphous silicon layer is in the range of 10 / V·s. -3 ~10 -2 cm 2 / V·s; or the conductivity of the doped microcrystalline silicon layer is in the range of 10. -1 ~10 0 S / cm, the conductivity of the doped amorphous silicon layer is in the range of 10. -5 ~10 -3 S / cm.

[0009] In one alternative embodiment, the second passivation contact structure extends to both sides to cover a portion of the surface of the first passivation contact structure and forms an opening that exposes a portion of the first passivation contact structure, and the first electrode is disposed in the opening.

[0010] The back-contact solar cell further includes a first transparent conductive layer and / or a second transparent conductive layer; the first transparent conductive layer includes a first transparent conductive layer body disposed on the doped polycrystalline silicon exposed by the opening, and a first electrode disposed on the first transparent conductive layer body; the second transparent conductive layer includes a second transparent conductive layer body disposed on the second contact area, and a second electrode disposed on the second transparent conductive layer.

[0011] In one optional embodiment, the width of the first transparent conductive layer is greater than the width of the first electrode and less than or equal to the width of the opening; the width of the second transparent conductive layer is greater than the width of the second electrode and less than or equal to the width of the second region.

[0012] In one optional embodiment, the first transparent conductive layer further includes: a first extension portion extending from the main body of the first transparent conductive layer to both sides to cover the second non-contact area; the second transparent conductive layer further includes a second extension portion extending from the main body of the second transparent conductive layer to both sides to cover the second non-contact area, the second extension portion and the first extension portion being isolated on the second non-contact area.

[0013] In one alternative embodiment, the resistivity of the first transparent conductive layer body is lower than the resistivity of the first extension, or the carrier mobility of the first transparent conductive layer body is lower than the carrier mobility of the first extension, or the light transmittance of the first transparent conductive layer body is less than or equal to the light transmittance of the first extension.

[0014] The resistivity of the second transparent conductive layer body is lower than that of the second extension, or the carrier mobility of the second transparent conductive layer body is lower than that of the second extension, or the light transmittance of the second transparent conductive layer body is lower than that of the second extension.

[0015] In one optional embodiment, the resistivity of the first transparent conductive layer and the second transparent conductive layer is less than or equal to 8 × 10⁻⁶. -4 Ω·cm, the resistivity of the first and second extensions is greater than 8×10 Ω·cm -4 Ω·cm; or the carrier mobility of the first transparent conductive layer and the second transparent conductive layer is less than or equal to 30 cm⁻¹. 2 / V·s, the carrier mobility of the first and second extensions is greater than 30 cm⁻¹. 2 / V·s and less than or equal to 120 cm 2 / V·s; or the light transmittance of the main body of the first transparent conductive layer and the main body of the second transparent conductive layer is less than or equal to 82%.

[0016] This disclosure also provides a method for fabricating a back-contact solar cell, comprising:

[0017] A substrate layer is provided, the substrate layer including a light-receiving surface and a back-lighting surface disposed opposite to each other, the back-lighting surface including a first region and a second region arranged alternately;

[0018] A first passivation contact structure is formed in the first region. The first passivation contact structure includes a tunneling oxide layer and a doped polysilicon layer stacked together. The tunneling oxide layer is disposed relatively close to the backlight surface.

[0019] A second passivation contact structure is formed in at least a second region. The second passivation contact structure includes a first structural layer and a second structural layer stacked together. The first structural layer is disposed relatively close to the backlight surface. The first structural layer includes an adjacent first contact area and a first non-contact area. The first contact area includes an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the first non-contact area includes an intrinsic amorphous silicon layer. The second structural layer includes an adjacent second contact area and a second non-contact area. The second contact area includes a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, and the second non-contact area includes a doped amorphous silicon layer. The first contact area and the second contact area at least partially overlap and cover a portion of the second region.

[0020] A first electrode and a second electrode are formed, wherein the first electrode is connected to the doped polycrystalline silicon layer and the second electrode is connected to the second contact region.

[0021] In one alternative implementation, forming a second passivated contact structure in at least a second region includes: forming a first structural layer and a second structural layer using a laser crystallization process.

[0022] In one alternative embodiment, after forming the second passivation contact structure in at least the second region and before forming the first electrode and the second electrode, the method further includes: forming a first transparent conductive layer on the first region that at least partially covers the first passivation contact structure, and / or forming a second transparent conductive layer on the second region that at least partially covers the second passivation contact structure.

[0023] This disclosure has the following beneficial effects:

[0024] 1. The back-contact solar cell disclosed herein has a first passivation contact structure comprising a tunneling oxide layer and a doped polycrystalline silicon layer of the TOPCon cell type, and a second passivation contact structure comprising a first structural layer and a second structural layer stacked together of the heterojunction cell type. The first structural layer comprises a first contact region composed of an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer and a first non-contact region composed of an intrinsic amorphous silicon layer. The second structural layer comprises a second contact region composed of a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer and a second non-contact region composed of a doped amorphous silicon layer. The first electrode is connected to the doped polycrystalline silicon layer, and the second electrode is connected to the second contact region. That is, the first and second contact areas, which are directly connected to the second electrode, are made of microcrystalline silicon or nanocrystalline silicon with high crystallinity, which gives them good electrical conductivity and significantly improves contact performance. Compared with using a doped amorphous silicon layer, this also reduces the parasitic absorption of the battery as a whole. The first and second non-contact areas, which are not directly connected to the second electrode, are made of amorphous silicon, which gives them better passivation performance. This optimizes the characteristic matching of different areas and greatly improves the power generation performance of the second passivation contact structure and the overall power generation performance of the battery.

[0025] 2. The back-contact solar cell of this disclosure further includes a first transparent conductive layer and / or a second transparent conductive layer to optimize carrier transport and interface performance between the passivated contact structure and the electrode. The first transparent conductive layer may consist only of the main portion of the first transparent conductive layer disposed between the first electrode and the first passivated contact structure. Similarly, the second transparent conductive layer may consist only of the main portion of the second transparent conductive layer disposed between the second electrode and the second passivated contact structure, with no transparent conductive layer material disposed in other areas, to reduce parasitic absorption of the transparent conductive film. Of course, in addition to the main portions of the first and second transparent conductive films, the first transparent conductive layer may also have first extension portions extending to both sides from the main portion of the first transparent conductive layer. Similarly, the second transparent conductive layer may also have second extension portions extending to both sides from the main portion of the second transparent conductive layer. In this case, the resistivity, carrier mobility, and transmittance of the main portion of the first transparent conductive layer are all lower than those of the first extension portion. Similarly, the resistivity, carrier mobility, and transmittance of the main portion of the second transparent conductive layer are all lower than those of the second extension portion, further balancing the electrical and optical performance of the back-contact solar cell.

[0026] 3. The back-contact solar cell prepared by the method disclosed herein has the aforementioned beneficial effects.

[0027] 4. In the back-contact solar cell fabrication method disclosed herein, a first structural layer and a second structural layer composed of different materials in different regions are obtained using laser crystallization. A high-energy-density laser beam irradiates the amorphous material for an extremely short time, causing its surface or interior to instantly heat to a molten state, followed by rapid cooling, inducing the material to transform from a disordered amorphous structure into an ordered crystalline structure. Compared to traditional stepwise fabrication processes using masks and localized removal, laser crystallization can rapidly and accurately achieve film layer fabrication, with high process compatibility. High-speed heating and cooling avoids heat diffusion to the substrate layer, reducing the risk of damage. The laser spot can be focused to the sub-micron level, achieving high-precision crystallization in micro-regions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a back-contact solar cell according to an embodiment of this disclosure;

[0030] Figure 2 This is a schematic diagram of the structure of a back-contact solar cell according to an embodiment of the present disclosure, wherein only the second transparent conductive layer is provided on the second contact area of ​​the second passivated contact structure;

[0031] Figure 3 This is a schematic diagram of the structure of a back-contact solar cell according to an embodiment of the present disclosure, wherein a second transparent conductive layer is disposed on the second contact area of ​​the second passivated contact structure, and a first transparent conductive layer is disposed on the doped polycrystalline silicon layer exposed by the opening of the second passivated contact structure.

[0032] Figure 4 This is a schematic diagram of the structure of a back-contact solar cell provided with a first transparent conductive layer and a second transparent conductive layer according to an embodiment of the present disclosure;

[0033] Figure 5 This is a schematic diagram of a back-contact solar cell according to an embodiment of the present disclosure, wherein the first transparent conductive layer includes a first transparent conductive layer body and a first extension with different parameters, and the second transparent conductive layer includes a second transparent conductive layer body and a second extension with different parameters;

[0034] Figure 6 This is a schematic flowchart of a method for fabricating a back-contact solar cell according to an embodiment of the present disclosure.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Base layer; 11. Light-receiving surface; 12. Backlight-receiving surface; 121. First region; 122. Second region;

[0037] 2. First passivation contact structure; 21. Tunneling oxide layer; 22. Doped polysilicon layer;

[0038] 3. Second passivated contact structure; 31. First structural layer; 311. First contact area; 312. First non-contact area; 32. Second structural layer; 321. Second contact area; 322. Second non-contact area; 30. Opening;

[0039] 41. First electrode; 42. Second electrode;

[0040] 5. First transparent conductive layer; 51. Main portion of the first transparent conductive layer; 52. First extension portion;

[0041] 6. Second transparent conductive layer; 61. Main body of the second transparent conductive layer; 62. Second extension;

[0042] 7. Suede-like texture;

[0043] 8. Passivation and anti-reflection layer. Detailed Implementation

[0044] The present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the present disclosure and not intended to limit it. It should also be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the drawings, not all structures. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure. The accompanying drawings show various structural schematic diagrams according to embodiments of the present disclosure. These drawings are not drawn to scale, and some details are enlarged for clarity and may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of this disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if one layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component can be "below" that other layer / component.

[0045] refer to Figures 1 to 5This disclosure provides a back-contact solar cell, comprising: a substrate layer 1, a first passivation contact structure 2, a second passivation contact structure 3, a first electrode 41, and a second electrode 42. The substrate layer 1 includes a light-receiving surface 11 and a back-lighting surface 12 disposed opposite to each other. The back-lighting surface 12 includes alternating first regions 121 and second regions 122. The first passivation contact structure 2 is located in the first region 121 and includes a tunneling oxide layer 21 and a doped polycrystalline silicon layer 22 stacked together. The tunneling oxide layer 21 is disposed relatively close to the back-lighting surface 12. The second passivation contact structure 3 is located at least in the second region 122 and includes a first structural layer 31 and a second structural layer 32 stacked together. The first structural layer 31 is disposed relatively close to the back-lighting surface 42. The backlight surface 12 is provided; the first structural layer 31 includes an adjacent first contact area 311 and a first non-contact area 312, the first contact area 311 includes an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the first non-contact area 312 includes an intrinsic amorphous silicon layer; the second structural layer 32 includes an adjacent second contact area 321 and a second non-contact area 322, the second contact area 321 includes a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, and the second non-contact area 322 includes a doped amorphous silicon layer, the first contact area 311 and the second contact area 321 at least partially overlap, and cover a portion of the second region 122; the first electrode 41 is connected to the doped polycrystalline silicon layer 22, and the second electrode 42 is connected to the second contact area 321.

[0046] Specifically, in the first passivation contact structure 2 and the second passivation contact structure 3, one of them has a p-type conductivity and the other has an n-type conductivity. In this embodiment, the first passivation contact structure 2 is n-type and the second passivation contact structure 3 is p-type, that is, an n-region structure is formed on the first region 121 of the backlight surface 12, and a p-region structure is formed on the second region 122. First, a tunneling oxide layer 21 and an n-type doped polysilicon layer 22 are sequentially formed on several first regions 121 to form a first passivation contact structure 2. Then, a groove is formed between adjacent first passivation contact structures 2, exposing the first region 121. Subsequently, a second passivation contact structure 3 is formed at the groove. The second passivation contact structure 3 can be formed only in the second region 122 within the groove, or it can extend to both sides to cover part of the surface of the first passivation contact structure 2. The first passivation contact structure 2 is connected to the first electrode 41 by an ohmic contact, and the second passivation contact structure 3 is connected to the second electrode 42 by an ohmic contact. The first electrode 41 and the second electrode 42 can be gate lines made of metal materials with good conductivity, such as silver, aluminum, and copper. The second passivation contact structure 3 includes a first structural layer 31 and a second structural layer 32 in the stacking direction. The first structural layer 31 mainly plays a role in chemical passivation, reducing the interface defect state density and carrier recombination. The second structural layer 32 is used to form a built-in electric field, establish an ohmic contact, and optimize carrier transport and light absorption.

[0047] While amorphous silicon generally exhibits better passivation properties than microcrystalline and nanocrystalline silicon, microcrystalline and nanocrystalline silicon offer superior contact and optical properties compared to amorphous silicon. (Reference) Figure 1 In the embodiments of this disclosure, the first structural layer 31 and the second structural layer 32 are both divided into two parts. The first contact area 311 and the second contact area 321 that are in contact with the second electrode 42 at least partially overlap to ensure better interfacial contact passivation performance. The first contact area 311 and the second contact area 321 are both made of microcrystalline silicon or nanocrystalline silicon. The first contact area 311 is an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the second contact area 321 is a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer. The first non-contact area 312 that is not in contact with the second electrode 42 is located on both sides of the first contact area 311, and the second non-contact area 322 is located on both sides of the second contact area 321. The first non-contact area 312 and the second non-contact area 322 are both made of amorphous silicon. The first non-contact area 312 is an intrinsic amorphous silicon layer, and the second non-contact area 322 is a doped amorphous silicon layer. Based on this, the first contact area 311 and the second contact area 321 corresponding to the second electrode 42 have good electrical conductivity, and the contact resistance is effectively reduced, which means that the contact performance of the second passivation contact structure 3 is greatly improved. Moreover, the band gap of the microcrystalline silicon material is slightly wider, usually 1.8~2.0 eV, and the crystalline phase reduces the tail state, which significantly reduces parasitic absorption compared to amorphous silicon material. Therefore, compared to using a completely doped amorphous silicon layer, the second structural layer 32, i.e., the second contact area 321, uses a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, which makes the overall parasitic absorption of the battery also lower. The first non-contact area 312 and the second non-contact area 322, which are not corresponding to the second electrode 42, have better passivation performance, optimize the characteristic matching of different areas, and greatly improve the power generation performance of the battery in the second area 122 and the overall power generation performance of the battery.

[0048] In one embodiment, reference Figures 1 to 5 The width of the first contact area 311 is greater than or equal to the width of the second electrode 42 and less than or equal to the width of the second region 122; the width of the second contact area 321 is greater than or equal to the width of the second electrode 42 and less than or equal to the width of the second region 122.

[0049] Specifically, the first contact area 311 and the second contact area 321 are both formed within the groove between adjacent first passivation contact structures 2 to ensure the subsequent fabrication of the second electrode 42. The partial overlap of the first contact area 311 and the second contact area 321 can be achieved by the projection areas of the first contact area 311 and the second contact area 321 on the substrate layer 1 partially overlapping, or by the projection areas of the first contact area 311 and the second contact area 321 being completely identical on the substrate layer 1, or by one of the projection areas being within the other's projection area. The key is to ensure that the area containing the first contact area 311 and the second contact area 321 includes the projection area of ​​the second electrode 42, ensuring good contact and conductivity with the second electrode 42. The remaining portion is made of amorphous silicon material, making the second passivation contact structure 3 a hybrid structure, thus optimizing the overall battery performance. In the embodiments of this disclosure, it is preferable that the projection areas of the first contact area 311 and the second contact area 321 are completely identical, improving film layer matching performance while simplifying the fabrication process.

[0050] In one embodiment, in the second structural layer 32, the crystallinity of the second contact region 321 is greater than that of the second non-contact region 322, or the carrier mobility of the second contact region 321 is greater than that of the second non-contact region 322, or the electrical conductivity of the second contact region 321 is greater than that of the second non-contact region 322.

[0051] In the embodiments of this disclosure, the crystallinity, carrier mobility, and conductivity of the second contact region 321 are all superior to those of the second non-contact region 322. Materials with high crystallinity have more ordered internal atomic arrangements, forming more grains and grain boundaries, and their lattice gaps and grain boundary densities are smaller, greatly reducing internal defects. Therefore, the prepared film has higher quality, and the crystalline structure also provides a smoother transport channel for carriers, resulting in higher carrier transport efficiency, i.e., higher carrier mobility, thereby reducing recombination losses. At the same time, higher conductivity means lower internal resistance, which can more effectively output photogenerated carriers, ultimately improving the photoelectric conversion efficiency of the battery. Therefore, the second contact region 321 in the embodiments of this disclosure has good interface performance between the first contact region 311 and the second electrode 42, greatly improving battery performance and photoelectric conversion efficiency.

[0052] In one embodiment, taking the second contact region 321 as a doped microcrystalline silicon layer and the second non-contact region 322 as a doped amorphous silicon layer as an example, the crystallinity of the doped microcrystalline silicon layer ranges from 30% to 80%, and the crystallinity of the doped amorphous silicon layer is less than 30%; the carrier mobility of the doped microcrystalline silicon layer ranges from 10... -1 ~10 0 cm 2 The carrier mobility of the doped amorphous silicon layer is in the range of 10 / V·s. -3 ~10 -2 cm 2 / V·s; the conductivity of the doped microcrystalline silicon layer ranges from 10⁻⁶ V·s. -1 ~10 0 S / cm, the conductivity of the doped amorphous silicon layer is in the range of 10. -5 ~10 -3 S / cm.

[0053] Within the above parameter range, the second contact region 321 has better crystallinity, carrier mobility and conductivity than the second non-contact region 322, and the characteristic performance matching of different surfaces is better. The high crystallinity, high carrier mobility and high conductivity work together to significantly improve the photoelectric conversion efficiency of the back contact solar cell.

[0054] refer to Figures 2 to 5 In one embodiment, the second passivation contact structure 3 extends to both sides to cover a portion of the surface of the first passivation contact structure 2 and forms an opening 30 that exposes a portion of the first passivation contact structure 2, and the first electrode 41 is disposed at the opening 30.

[0055] The hybrid passivated back contact battery of this disclosure embodiment further includes a first transparent conductive layer 5 and / or a second transparent conductive layer 6. That is, the first transparent conductive layer 5 can be provided only between the first passivated contact structure 2 and the first electrode 41, or the second transparent conductive layer 6 can be provided only between the second passivated contact structure 3 and the second electrode 42. Alternatively, the first transparent conductive layer 5 can be provided between the first passivated contact structure 2 and the first electrode 41, and the second transparent conductive layer 6 can also be provided between the second passivated contact structure 3 and the second electrode 42.

[0056] It should be noted that, since the n-type doped polycrystalline silicon layer 22, also known as n-poly, has the characteristics of high crystallinity, good film density, and low resistivity, it has better carrier transport performance compared to the p-type doped amorphous silicon layer. Therefore, a transparent conductive layer can be formed only in the groove portion of the p-region, while no transparent conductive film is formed in the other regions, which can reduce the parasitic absorption of the transparent conductive film. Therefore, in the embodiments of this disclosure, it is preferred that both the n-region and the p-region have transparent conductive layers, or that a transparent conductive layer is formed only in the p-region.

[0057] In one alternative implementation, refer to Figure 3 The first transparent conductive layer 5 may consist only of the first transparent conductive layer body 51 disposed in the opening 30 region of the second passivated contact structure 3. The first transparent conductive layer body 51 is disposed on the doped polysilicon exposed in the opening 30, and the first electrode 41 is disposed on the first transparent conductive layer body 51. (Reference) Figure 2 and Figure 3The second transparent conductive layer 6 may consist only of the main body 61 of the second transparent conductive layer disposed in the groove region between adjacent first passivation contact structures 2. The main body 61 of the second transparent conductive layer is disposed on the second contact area 321 and may have a certain distance between it and the sidewall of the first passivation contact structure 2. The second electrode 42 is disposed on the second transparent conductive layer 6. In this case, the transparent conductive film is disposed only in the area where the electrode is disposed, and the transparent conductive film in other areas is eliminated. This helps to reduce the coverage area of ​​the transparent conductive film, that is, to reduce the parasitic absorption caused by the transparent conductive film, thereby improving the optical performance of the battery.

[0058] In one embodiment, the width of the first transparent conductive layer 51 is greater than the width of the first electrode 41 and less than or equal to the width of the opening 30, ensuring the flatness of the first transparent conductive layer 51, thereby improving its conductivity and thus enhancing the carrier transport performance between the first electrode 41 and the doped polysilicon layer 22. The width of the second transparent conductive layer 61 is greater than the width of the second electrode 42 and less than or equal to the width of the second region 122, further ensuring the flatness of the second transparent conductive layer 61, thereby improving its conductivity and the carrier transport performance between the second electrode 42 and the second contact region 321. In the embodiments of this disclosure, preferably, the width of the first transparent conductive layer 51 is the same as the width of the opening 30, and the width of the second transparent conductive layer 61 is the same as the width of the first contact region 311, maximizing the carrier transport efficiency.

[0059] In another alternative embodiment, refer to Figure 4 and Figure 5 The first transparent conductive layer 5 further includes a first extension 52, which extends from the main body 51 of the first transparent conductive layer to both sides to cover the second non-contact area 322; the second transparent conductive layer 6 further includes a second extension 62, which extends from the main body 61 of the second transparent conductive layer to both sides to cover the second non-contact area 322, and the second extension 62 and the first extension 52 are isolated on the second non-contact area 322.

[0060] In other words, in addition to setting the transparent conductive film body in the electrode area, the transparent conductive film material can also be extended in other areas, that is, the first extension 52 and the second extension 62 are set to improve the carrier collection efficiency.

[0061] Based on this, refer to Figure 5In one embodiment, the resistivity of the first transparent conductive layer 51 is lower than the resistivity of the first extension 52, or the carrier mobility of the first transparent conductive layer 51 is lower than the carrier mobility of the first extension 52, or the light transmittance of the first transparent conductive layer 51 is less than or equal to the light transmittance of the first extension 52; the resistivity of the second transparent conductive layer 61 is lower than the resistivity of the second extension 62, or the carrier mobility of the second transparent conductive layer 61 is lower than the carrier mobility of the second extension 62, or the light transmittance of the second transparent conductive layer 61 is lower than the light transmittance of the second extension 62.

[0062] In one embodiment, the first transparent conductive layer 51 corresponding to the contact area in the first transparent conductive layer 5 can be made of a material with relatively low resistivity, carrier mobility and light transmittance, while the first extension 52 in other areas can be made of a conventional material with relatively high resistivity, carrier mobility and light transmittance, so as to further balance the electrical and optical performance of the back contact solar cell.

[0063] Specifically, firstly, resistivity is inversely proportional to carrier concentration; the higher the carrier concentration, the lower the resistivity. Secondly, carrier mobility and parasitic absorption of the film are also inversely proportional to carrier concentration. For transparent conductive films in contact with metal electrodes, the resistivity of the film layer has a significant impact on contact performance. To reduce contact resistance, the carrier concentration needs to be increased. However, a higher carrier concentration also enhances impurity scattering, leading to a decrease in carrier mobility. Simultaneously, free carrier absorption is also enhanced, exacerbating parasitic absorption in the film layer. Therefore, to fully utilize the characteristics of different transparent conductive films, contact performance is prioritized in the electrode contact area, thus using transparent conductive film materials with lower resistivity, such as ITO films. In non-electrode contact areas, optical performance is prioritized, selecting transparent conductive film materials with higher carrier mobility and transmittance, such as hydrogen-doped indium oxide (InO:H), which exhibits strong optical performance.

[0064] In one specific embodiment, the resistivity of the first transparent conductive layer 51 and the second transparent conductive layer 61 is less than or equal to 8 × 10⁻⁶. -4 Ω·cm, carrier mobility less than or equal to 30 cm 2 / V·s, transmittance less than or equal to 82%. The resistivity of the first extension 52 and the second extension 62 is greater than 8×10⁻⁶. -4 Ω·cm, carrier mobility greater than 30 cm 2 / V·s and less than 120 cm 2 / V·s, the transmittance can be less than or equal to 89%, but greater than the transmittance of the first transparent conductive layer body 51 and the second transparent conductive layer body 61.

[0065] Within the aforementioned parameter range, the first transparent conductive layer 51 and the second transparent conductive layer 61 have optimal contact performance that matches the hybrid passivated contact structure of the present disclosure embodiment, while the first extension 52 and the second extension 62 also have matching optical performance, which helps to improve the photoelectric conversion efficiency of the battery.

[0066] In back-contact solar cells, even the selective arrangement of specific film materials and coverage areas regarding the passivation contact structure and transparent conductive layer can have a significant impact on cell performance and photoelectric conversion efficiency. Therefore, electrical performance tests were conducted on comparative cells and cells from the embodiments of this disclosure with different configurations. It was found that the n-region passivation contact structure in both the comparative cells and the cells from the embodiments of this disclosure consists of an intrinsic polycrystalline silicon layer and a doped polycrystalline silicon layer; the difference lies in the arrangement of the p-region passivation contact structure and the different arrangements of the transparent conductive film. Based on this, the electrical performance test data for different comparative cells and cells from the embodiments of this disclosure are as follows:

[0067] Table 1. Electrical performance test results of each comparative example battery and the example battery.

[0068]

[0069] From the table above, it can be seen that, firstly, for the batteries of Comparative Example 1 and Comparative Example 2: In Comparative Example 1, the first structural layer 31 of the p-region passivation contact structure is an intrinsic amorphous silicon layer of a single material, and the second structural layer 32 is a doped amorphous silicon layer of a single material composition; in Comparative Example 2, the first structural layer 31 of the p-region passivation contact structure is an intrinsic amorphous silicon layer of a single material composition, and the second structural layer 32 is a partitioned arrangement of two material compositions: a doped microcrystalline silicon layer and a doped amorphous silicon layer. Furthermore, the transparent conductive layers of Comparative Example 1 and Comparative Example 2 are conventional designs, as shown in the appendix to this disclosure. Figure 4 The transparent conductive layer shown is configured as follows. From the above data, it can be seen that in Comparative Example 2, in the contact region corresponding to the second electrode 42, partially transforming the doped amorphous silicon layer of the second structural layer 32 in the p-region into a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer can further improve contact performance and reduce parasitic absorption of the doped amorphous silicon layer at this location. Therefore, Comparative Example 2 achieves higher conversion efficiency (…). η ), open circuit voltage ( V oc ), short-circuit current density ( J sc ), fill factor ( FF All electrical performance parameters, such as those of the control sample, are higher than those of the control sample 1.

[0070] For Example 1: as follows Figure 4As shown, in the p-region passivation contact structure, the first structural layer 31 is partitioned with two materials: intrinsic microcrystalline silicon and intrinsic amorphous silicon. The second structural layer 32 is partitioned with two materials: doped microcrystalline silicon and doped amorphous silicon. Additionally, the transparent conductive layer in Example 1 is a conventional design. Specifically, in Example 1, a portion of the intrinsic amorphous silicon layer of the first structural layer 31 in the contact region corresponding to the second electrode 42 is also transformed into an intrinsic microcrystalline silicon or intrinsic nanocrystalline silicon layer. This is combined with a doped microcrystalline silicon or doped nanocrystalline silicon layer of the second structural layer 32 in that region. This arrangement of films with corresponding different compositional combinations in the stacking direction is more conducive to carrier collection and transport, and also reduces parasitic absorption of the intrinsic amorphous silicon material. Therefore, Example 1 achieves higher conversion efficiency (…). η ), open circuit voltage ( V oc ), short-circuit current density ( J sc ), fill factor ( FF All electrical performance parameters, such as those of the control sample, are higher than those of the control sample 2.

[0071] For Example 2: as Figure 2 As shown, in the p-region passivation contact structure, the first structural layer 31 is composed of two materials: intrinsic microcrystalline silicon and intrinsic amorphous silicon, and the second structural layer 32 is composed of two materials: doped microcrystalline silicon and doped amorphous silicon. Furthermore, the transparent conductive layer in Example 2 is only provided in the groove contact area of ​​the p-region. Since the transparent conductive film also exhibits parasitic absorption, reducing the coverage area of ​​the transparent conductive film helps to further improve the optical performance of the battery. Secondly, since the conductivity of the doped microcrystalline silicon or nanocrystalline silicon layer is weaker than that of n-type doped polycrystalline silicon (i.e., n-poly), the transparent conductive film can be provided only on the surface of the corresponding doped microcrystalline silicon or doped nanocrystalline silicon layer in contact with the second electrode 42 in the p-region, i.e., only the second transparent conductive layer body 61 is provided. This helps to balance the performance of both carrier transport and parasitic absorption, thus the overall electrical performance of Example 2 is higher than that of Example 1.

[0072] For Example 3: as follows Figure 3As shown, in the p-region passivation contact structure, the first structural layer 31 is composed of two materials: intrinsic microcrystalline silicon and intrinsic amorphous silicon, and the second structural layer 32 is composed of two materials: doped microcrystalline silicon and doped amorphous silicon. Furthermore, in Example 2, the transparent conductive layer is only present on the surface of the first passivation contact structure 2 exposed at the opening 30 of the second passivation contact structure 3 in the n-region and in the groove contact area of ​​the p-region. In Example 3, the transparent conductive film exists only on the n-poly exposed at the opening 30 and on the doped microcrystalline silicon or doped nanocrystalline silicon layer; that is, only the first transparent conductive layer body 51 and the second transparent conductive layer body 61 are provided. Compared to Example 2, the parasitic absorption area of ​​the corresponding transparent conductive film in Example 3 is slightly increased, but the conductivity of the n-poly surface is slightly improved. Therefore, the overall battery performance is not significantly different from that of Example 2.

[0073] For Example 4: Reference Figure 5 In the p-region passivation contact structure, the first structural layer 31 is composed of two materials: intrinsic microcrystalline silicon and intrinsic amorphous silicon, and the second structural layer 32 is composed of two materials: doped microcrystalline silicon and doped amorphous silicon. This differentiates the characteristics of the transparent conductive film. By changing the mobility or conductivity of the transparent conductive film in the contact area, the mobility and conductivity of the transparent conductive layer itself are higher than those of the extension, which helps to further improve the contact performance in this area. Meanwhile, the characteristics of the transparent conductive film in the non-contact area remain unchanged to ensure high film transmittance, thus achieving optimal battery performance.

[0074] In addition, refer to Figures 1 to 5 In the embodiments of this disclosure, the substrate layer 1 forms a textured structure 7 on one side of the light-receiving surface 11, and a passivation antireflection layer 8 is covered on the textured structure 7. The passivation antireflection layer 8 can be a stacked structure composed of two or more of aluminum oxide, silicon nitride, silicon oxide, and silicon oxynitride.

[0075] The embodiments of this disclosure also disclose a method for fabricating a back-contact solar cell, used to fabricate the aforementioned back-contact solar cell. Figure 6 This is a schematic diagram of the preparation method, which specifically includes the following steps:

[0076] Step S601, a substrate layer 1 is provided. The substrate layer 1 includes a light-receiving surface 11 and a backlight surface 12 disposed opposite to each other. The backlight surface 12 includes a first region 121 and a second region 122 arranged alternately.

[0077] Specifically, the substrate 1 can be a silicon substrate, formed by polishing a silicon wafer on both sides. It is divided into a first region 121 and a second region 122 of different polarities on one side of the backlight surface 12. When the passivation contact structure is prepared by doping in this region, an inner extension layer of the corresponding polarity is also formed on the surface of this region.

[0078] In step S602, a first passivation contact structure 2 is formed in the first region 121. The first passivation contact structure 2 includes a tunneling oxide layer 21 and a doped polysilicon layer 22 stacked together. The tunneling oxide layer 21 is disposed relatively close to the backlight surface 12.

[0079] That is, a first passivation contact structure 2 of the TOPCon battery type is fabricated in the first region 121 of the backlight surface 12. The first passivation contact structure 2 includes a tunneling oxide layer 21 stacked on the surface of the first region 121 and a doped polycrystalline silicon layer 22 disposed on the tunneling oxide layer 21. The first passivation contact structure 2 can be n-type or p-type. In the embodiments of this disclosure, the first passivation contact structure 2 is n-type as an example for explanation.

[0080] In step S603, a second passivation contact structure 3 is formed in at least the second region 122. The second passivation contact structure 3 includes a first structural layer 31 and a second structural layer 32 stacked together. The first structural layer 31 is disposed relatively close to the backlight surface 12. The first structural layer 31 includes an adjacent first contact area 311 and a first non-contact area 312. The first contact area 311 includes an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the first non-contact area 312 includes an intrinsic amorphous silicon layer. The second structural layer 32 includes an adjacent second contact area 321 and a second non-contact area 322. The second contact area 321 includes a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, and the second non-contact area 322 includes a doped amorphous silicon layer. The first contact area 311 and the second contact area 321 at least partially overlap and cover a portion of the second region 122.

[0081] Exemplarily, based on the already formed first passivated contact structure 2, a second passivated contact structure 3 is further fabricated in the second region 122 exposed between at least adjacent first passivated contact structures 2 on one side of the backlight surface 12. The second passivated contact structure 3 employs a first structural layer 31 and a second structural layer 32 of a heterojunction battery type. The first structural layer 31 includes a first contact region 311 and first non-contact regions 312 on both sides. The first contact region 311 employs an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer with a high crystallinity, while the first non-contact regions 312 employ an intrinsic amorphous silicon layer with a relatively low crystallinity. The second structural layer 32 includes a second contact region 321 and a second non-contact region 322. The second contact region 321 employs a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer with a high crystallinity, while the second non-contact region 322 employs a doped amorphous silicon layer with a relatively low crystallinity. Similarly, the above-mentioned second passivated contact structure 3 can be either n-type or p-type. In the embodiments of this disclosure, the second passivated contact structure 3 is described as p-type.

[0082] In step S604, a first electrode 41 and a second electrode 42 are formed. The first electrode 41 is connected to the doped polycrystalline silicon layer 22, and the second electrode 42 is connected to the second contact region 321.

[0083] After printing a low-temperature paste on the first passivation contact structure 2 in the first region 121, sintering is performed to form a first electrode 41 in ohmic contact with the doped polycrystalline silicon layer 22. Similarly, after printing a low-temperature paste on the second passivation contact structure 3 in the second region 122, sintering is performed to form a second electrode 42 in ohmic contact with the second contact region 321.

[0084] In summary, in the back-contact solar cell fabrication method disclosed herein, a second passivation contact structure 3 of heterojunction cell type is selected. The first contact region 311 and the second contact region 321, which are directly connected to the second electrode 42, are made of microcrystalline silicon or nanocrystalline silicon material with high crystallinity, which gives them good electrical conductivity and significantly improves contact performance. Compared with using a doped amorphous silicon layer, this also reduces the parasitic absorption of the entire cell. The first non-contact region 312 and the second non-contact region 322, which are not directly connected to the second electrode 42, are both made of amorphous silicon material, which gives them better passivation performance. This optimizes the characteristic matching of different regions and greatly improves the power generation performance of the second passivation contact structure 3 and the overall power generation performance of the cell.

[0085] In one embodiment, step S603, which involves forming a second passivated contact structure 3 in at least the second region 122, includes forming a first structural layer 31 and a second structural layer 32 using a laser crystallization process.

[0086] The first structural layer 31 and the second structural layer 32 are obtained using a laser crystallization process. Specifically, an amorphous material (such as amorphous silicon) is irradiated with a high-energy-density laser beam (such as an excimer laser or picosecond laser) for an extremely short time (nanosecond to picosecond level), causing its surface or interior to heat up to a molten state instantaneously, followed by rapid cooling, inducing the material to transform from a disordered amorphous structure into an ordered crystalline structure. Compared with traditional stepwise fabrication processes that utilize masks and localized removal, laser crystallization can achieve rapid and precise film preparation, and has high process compatibility. The high-speed heating and cooling can prevent heat diffusion to the substrate layer 1, reducing the risk of damage. The laser spot can be focused to the submicron level, achieving high-precision crystallization in micro-regions.

[0087] In one embodiment, after step S603 of forming the second passivation contact structure 3 in at least the second region 122 and before step S604 of forming the first electrode 41 and the second electrode 42, the method further includes: forming a first transparent conductive layer 5 on the first region 121 that at least partially covers the first passivation contact structure 2, and / or forming a second transparent conductive layer 6 on the second region 122 that at least partially covers the second passivation contact structure 3. The transparent conductive layer helps to enhance the carrier transport efficiency between the passivation contact structure and the electrode, balancing the electrical and optical performance of the battery, thereby improving the photoelectric conversion efficiency of the battery. Further functional descriptions of the above structures are the same as in the corresponding embodiments described above, and will not be repeated here.

[0088] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0089] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A back-contact solar cell, characterized in that, include: A substrate layer, the substrate layer comprising a light-receiving surface and a backlight surface disposed opposite to each other, the backlight surface comprising an alternately arranged first region and a second region; A first passivation contact structure is located in the first region. The first passivation contact structure includes a tunneling oxide layer and a doped polysilicon layer stacked together. The tunneling oxide layer is disposed relatively close to the backlight surface. A second passivation contact structure is located at least in the second region. The second passivation contact structure includes a first structural layer and a second structural layer stacked together. The first structural layer is disposed relatively close to the backlight surface. The first structural layer includes an adjacent first contact area and a first non-contact area. The first contact area includes an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer, and the first non-contact area includes an intrinsic amorphous silicon layer. The second structural layer includes an adjacent second contact area and a second non-contact area. The second contact area includes a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer, and the second non-contact area includes a doped amorphous silicon layer. The first contact area and the second contact area at least partially overlap and cover a portion of the second region. A first electrode and a second electrode, wherein the first electrode is connected to the doped polycrystalline silicon layer and the second electrode is connected to the second contact area.

2. The back-contact solar cell according to claim 1, characterized in that, The width of the first contact area is greater than or equal to the width of the second electrode, and less than or equal to the width of the second region; The width of the second contact area is greater than or equal to the width of the second electrode, and less than or equal to the width of the second region.

3. The back-contact solar cell according to claim 1, characterized in that, In the second structural layer, the crystallinity of the second contact region is greater than that of the second non-contact region, or the carrier mobility of the second contact region is greater than that of the second non-contact region, or the electrical conductivity of the second contact region is greater than that of the second non-contact region.

4. The back-contact solar cell according to claim 1, characterized in that, The crystallinity of the doped microcrystalline silicon layer ranges from 30% to 80%, and the crystallinity of the doped amorphous silicon layer is less than 30%. Or the carrier mobility of the doped microcrystalline silicon layer is in the range of 10. -1 ~10 0 cm 2 / V·s, the carrier mobility of the doped amorphous silicon layer ranges from 10 -3 ~10 -2 cm 2 / V·s; Or the conductivity of the doped microcrystalline silicon layer is in the range of 10. -1 ~10 0 The conductivity of the doped amorphous silicon layer is in the range of 10 S / cm. -5 ~10 -3 S / cm.

5. The back-contact solar cell according to any one of claims 1-4, characterized in that, The second passivated contact structure extends to both sides to cover a portion of the surface of the first passivated contact structure and forms an opening that exposes a portion of the first passivated contact structure. The first electrode is disposed in the opening. The back contact solar cell further includes a first transparent conductive layer and / or a second transparent conductive layer. The first transparent conductive layer includes a first transparent conductive layer body, which is disposed on the doped polysilicon exposed by the opening, and the first electrode is disposed on the first transparent conductive layer body; The second transparent conductive layer includes a second transparent conductive layer body, which is disposed on the second contact area, and the second electrode is disposed on the second transparent conductive layer.

6. The back-contact solar cell according to claim 5, characterized in that, The width of the first transparent conductive layer is greater than the width of the first electrode, and less than or equal to the width of the opening; The width of the second transparent conductive layer is greater than the width of the second electrode, but less than or equal to the width of the second region.

7. The back-contact solar cell according to claim 5, characterized in that, The first transparent conductive layer further includes: a first extension portion, which extends from the main body of the first transparent conductive layer to both sides to cover the second non-contact area; The second transparent conductive layer further includes a second extension portion, which extends from the main body of the second transparent conductive layer to both sides to cover the second non-contact area. The second extension portion and the first extension portion are isolated on the second non-contact area.

8. The back-contact solar cell according to claim 7, characterized in that, The resistivity of the first transparent conductive layer body is lower than the resistivity of the first extension, or the carrier mobility of the first transparent conductive layer body is lower than the carrier mobility of the first extension, or the light transmittance of the first transparent conductive layer body is less than or lower than the light transmittance of the first extension. The resistivity of the second transparent conductive layer body is lower than the resistivity of the second extension, or the carrier mobility of the second transparent conductive layer body is lower than the carrier mobility of the second extension, or the light transmittance of the second transparent conductive layer body is lower than the light transmittance of the second extension.

9. The back-contact solar cell according to claim 8, characterized in that, The resistivity of the first transparent conductive layer and the second transparent conductive layer is less than or equal to 8 × 10⁻⁶. -4 Ω·cm, the resistivity of the first extension and the second extension is greater than 8×10 Ω·cm -4 Ω·cm; Alternatively, the carrier mobility of the first transparent conductive layer and the second transparent conductive layer is less than or equal to 30 cm⁻¹. 2 / V·s, the carrier mobility of the first and second extensions is greater than 30 cm⁻¹. 2 / V·s and less than or equal to 120 cm 2 / V·s; Alternatively, the light transmittance of the first transparent conductive layer and the second transparent conductive layer is less than or equal to 82%.

10. A method for preparing a back-contact solar cell, used to prepare the back-contact solar cell according to any one of claims 1-9, characterized in that, include: A substrate layer is provided, the substrate layer including a light-receiving surface and a back-lighting surface disposed opposite to each other, the back-lighting surface including a first region and a second region arranged alternately; A first passivation contact structure is formed in the first region. The first passivation contact structure includes a tunneling oxide layer and a doped polysilicon layer stacked together. The tunneling oxide layer is disposed relatively close to the backlight surface. A second passivation contact structure is formed in at least the second region. The second passivation contact structure includes a first structural layer and a second structural layer stacked together. The first structural layer is disposed relatively close to the backlight surface. The first structural layer includes an adjacent first contact area and a first non-contact area. The first contact area includes an intrinsic microcrystalline silicon layer or an intrinsic nanocrystalline silicon layer. The first non-contact area includes an intrinsic amorphous silicon layer. The second structural layer includes an adjacent second contact area and a second non-contact area. The second contact area includes a doped microcrystalline silicon layer or a doped nanocrystalline silicon layer. The second non-contact area includes a doped amorphous silicon layer. The first contact area and the second contact area at least partially overlap and cover a portion of the second region. A first electrode and a second electrode are formed, wherein the first electrode is connected to the doped polycrystalline silicon layer and the second electrode is connected to the second contact region.

11. The method for fabricating a back-contact solar cell according to claim 10, characterized in that, The formation of a second passivated contact structure in at least the second region includes: forming a first structural layer and a second structural layer using a laser crystallization process.

12. The method for preparing a back-contact solar cell according to claim 10, characterized in that, After the second passivated contact structure is formed in at least the second region, and before the first electrode and the second electrode are formed, the method further includes: A first transparent conductive layer is formed on the first region, at least covering a portion of the first passivated contact structure, and / or a second transparent conductive layer is formed on the second region, at least covering a portion of the second passivated contact structure.

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