Hybrid passivated back contact solar cell and method of making same

Abstract

The present disclosure relates to the technical field of solar cells, and discloses a hybrid passivated back contact solar cell and a preparation method thereof. The cell comprises a substrate layer, a first passivated contact structure, a second passivated contact structure, a first electrode and a second electrode, wherein the substrate layer comprises opposite light-receiving and back surfaces; the first passivated contact structure comprises a tunneling oxide layer and a doped layer arranged in a stack; the second passivated contact structure comprises a charge transport layer covering at least the exposed back surface of the first passivated contact structure; the conductive types of the first passivated contact structure and the second passivated contact structure are opposite; the first electrode is connected with the doped layer, and the second electrode is connected with the charge transport layer. In the present disclosure, the n region of the back surface adopts the first passivated contact structure combining the tunneling oxide layer and the polycrystalline silicon doped layer, and the p region adopts the charge transport layer of the perovskite cell, thereby forming a hybrid passivated back contact cell, solving the problem of poor passivation contact performance of the p region of the TBC cell, and making the process simpler and the cost lower.

Description

Technical Field

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

[0002] Back-contact solar cells (BC cells) are a technology that transfers both the positive and negative electrodes to 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 cells, which combine back-contact solar cell technology with other types of solar cells, have attracted widespread attention. For example, the tunneling oxide passivated contact solar cell (TOPCon cell) technology, which combines BC cell technology, forms the tunneling oxide passivated back-contact cell (TBC cell). This cell applies the tunneling oxide passivation contact structure of the TOPCon cell to the back-contact structure, with all electrodes fabricated on the back of the cell. While retaining the high current advantage of the BC cell on the front, it further improves the open-circuit voltage and photoelectric conversion efficiency.

[0003] In TBC (Total Bioelectric Cell) solar cells, the p-type doped layer (p-poly) on the back is weaker than the n-type doped layer (n-poly) in both passivation and contact performance. Therefore, the performance of the p-type doped layer directly determines the photoelectric conversion efficiency of the cell, but it is difficult to significantly optimize its process. To address this, the industry has begun to use heterojunction passivation contact technology with intrinsic amorphous silicon / p-type doped amorphous silicon to replace the traditional p-type doped layer, thus forming hybrid (or hybrid) passivated back-contact solar cells. However, this heterojunction passivation contact technology typically requires low-temperature processes to achieve high-quality amorphous silicon film fabrication, which is technically challenging and costly, impacting the cell's photoelectric conversion efficiency and performance. Summary of the Invention

[0004] In view of this, this disclosure provides a hybrid passivated back contact solar cell and its fabrication method to solve the problems of high difficulty and cost in optimizing the back film layer of existing back contact solar cells, which affects the photoelectric conversion efficiency of the cell.

[0005] In a first aspect, this disclosure provides a hybrid passivated back-contact solar cell, comprising: a substrate layer, a first passivated contact structure, a second passivated 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. The first passivated contact structure includes a tunneling oxide layer and a doped layer stacked thereon, the tunneling oxide layer being disposed on a portion of the back-lighting surface, and the doped layer being disposed on the tunneling oxide layer. The second passivated contact structure includes a charge transport layer, the charge transport layer at least covering the back-lighting surface exposed by the first passivated contact structure. The first passivated contact structure and the second passivated contact structure have opposite conductivity types. The first electrode is connected to the doped layer, and the second electrode is connected to the charge transport layer.

[0006] Beneficial Effects: The hybrid passivated back-contact solar cell disclosed herein combines back-contact cell technology, TOPCon cell technology, and perovskite cell technology. The n-region of the back surface of the cell adopts a first passivation contact structure combining a tunneling oxide layer and a polycrystalline silicon doped layer, while the p-region adopts a second passivation contact structure that is the charge transport layer of a perovskite cell, specifically a hole transport layer. This forms a hybrid passivated back-contact solar cell. On the one hand, this hybrid passivated back-contact solar cell solves the problem of poor performance of p-poly thin films in traditional TBC cells. On the other hand, compared with the p-poly passivation contact method in TOPCon cells and the passivation contact method of intrinsic amorphous silicon / boron-doped amorphous silicon in heterojunction cells, the passivation contact method of the hole transport layer in perovskite cells has a simpler and lower cost thin film process, which is more conducive to obtaining a high-quality hybrid passivation structure, thereby obtaining a hybrid passivated back-contact solar cell with superior photoelectric conversion efficiency.

[0007] In one alternative implementation, the absolute value of the work function of the charge transport layer is less than or equal to 6 eV, and the thickness of the charge transport layer is greater than 100 nm.

[0008] Beneficial effects: Limiting the absolute value of the work function of the hole transport layer to less than or equal to 6 eV effectively reduces the contact barrier height, i.e., reduces the band bending height. This allows hole carriers at the top of the valence band in the silicon energy level to be transported to the hole transport layer more efficiently, effectively ensuring the hole carrier transport efficiency. Limiting the thickness of the charge transport layer, specifically the hole transport layer, to greater than 100 nm effectively covers the textured substrate layer, improving the reliability of the charge transport layer on the substrate layer.

[0009] In one optional embodiment, the first passivation contact structure further includes a first transparent conductive layer disposed on the doped layer, and a first electrode disposed on the first transparent conductive layer; the second passivation contact structure further includes a second transparent conductive layer disposed on the charge transport layer, and a second electrode disposed on the second transparent conductive layer; the first transparent conductive layer and the second transparent conductive layer are disposed at intervals.

[0010] Beneficial effects: The first and second transparent conductive layers have good light transmittance and conductivity, which can effectively extract the current in the doped layer and charge transport layer, respectively, thereby further improving the photoelectric conversion efficiency of the battery.

[0011] In one alternative embodiment, the charge transport layer of the second passivated contact structure covers the surface of the first passivated contact structure and the backlight surface not covered by the first passivated contact structure; the charge transport layer has an opening that exposes a portion of the doped layer; a first transparent conductive layer covers the opening to connect with the doped layer.

[0012] Beneficial effects: The first passivated contact structure covers a portion of the backlight surface, enabling the flow and conduction of one polarity of charge. The charge transport layer of the second passivated contact structure, while covering the exposed portion of the backlight surface to achieve charge conduction, also extends to cover a portion of the first passivated contact structure surface. The charge transport layer on the surface of the first passivated contact structure forms a first opening exposing a portion of the doped layer, allowing the first electrode or the first transparent conductive layer to connect to the doped layer through the first opening, thus achieving electrical connection. This approach increases the contact area between the second passivated contact structure and the silicon substrate, helping to improve the transport efficiency of charges of different polarities, thereby improving the photoelectric conversion efficiency of the battery.

[0013] In one alternative implementation, an isolation space is formed between the first passivated contact structure and the second passivated contact structure.

[0014] Beneficial effects: The first passivated contact structure and the second passivated contact structure are completely isolated by the isolation space, which is simple to prepare and greatly reduces the recombination of electrons and holes, thereby improving charge transport efficiency.

[0015] In one alternative embodiment, the second passivated contact structure further includes an interface passivation layer disposed between the charge transport layer and the substrate layer.

[0016] Beneficial effects: Setting an interface passivation layer between the charge transport layer and the substrate layer helps to reduce interface defects and suppress nonradiative recombination; it can also improve the band matching of the interface, block electrons, promote the separation of photogenerated carriers and subsequent transport efficiency; and improve the connection stability between the charge transport layer and the substrate layer, thereby improving the overall stability of the second passivation contact structure and even the battery.

[0017] In one alternative embodiment, the interface passivation layer includes one or more of the following: a silicon oxide layer, an aluminum oxide layer, and an intrinsic amorphous silicon layer.

[0018] Beneficial effects: The interface passivation layer can be made of a variety of materials, providing more structural possibilities for hybrid passivation back contact solar cells, enhancing the scope of application, and improving economic benefits.

[0019] In an alternative implementation, a passivation antireflection layer is further included, disposed on the light-receiving surface of the substrate layer.

[0020] Beneficial effects: Forming a passivation and antireflection layer on the light-receiving surface helps to further reduce optical losses on the light-receiving surface and improve battery power generation efficiency.

[0021] Secondly, this disclosure also provides a method for preparing a hybrid passivated back contact solar cell, comprising:

[0022] A base layer is provided, the base layer including a light-receiving surface and a backlighting surface disposed opposite to each other;

[0023] A first passivation contact structure is formed on the backlight surface. The first passivation contact structure includes a tunneling oxide layer and a doped layer stacked together. The tunneling oxide layer is disposed on a portion of the backlight surface, and the doped layer is disposed on the tunneling oxide layer.

[0024] A second passivation contact structure is formed on the backlight surface. The second passivation contact structure includes a charge transport layer that at least covers the backlight surface exposed by the first passivation contact structure. The first passivation contact structure has the opposite conductivity type to the second passivation contact structure.

[0025] A first electrode and a second electrode are formed, with the first electrode connected to the doped layer and the second electrode connected to the charge transport layer.

[0026] Beneficial effects: In the preparation method of the hybrid passivated back contact solar cell disclosed herein, firstly, a tunneling oxide layer and a doped layer are formed in the n region of the back surface of the substrate using TOPCon cell-related structures to achieve efficient electron transport; then, a hole transport layer is formed in the p region of the back surface using perovskite cell-related structures to achieve efficient hole transport. Different types of passivated contact structures are formed on one side of the back surface of the cell, resulting in good thin film performance in different polarity regions of the formed hybrid passivated back contact solar cell. The preparation process is simple, and it is economically efficient while improving the photoelectric conversion efficiency of the cell.

[0027] In one alternative embodiment, forming a second passivated contact structure on the backlight surface includes:

[0028] An initial charge transport layer is formed on the entire back surface side of the substrate layer, and the initial charge transport layer covers the first passivation contact structure and the back surface exposed by the first passivation contact structure.

[0029] A portion of the initial charge transport layer located on the first passivated contact structure is removed to form an opening that exposes the doped layer.

[0030] Beneficial effects: After covering the entire surface with the initial charge transport layer, the first opening is created on the first passivated contact structure by local removal methods such as laser. This not only provides a current outflow channel for the first passivated contact structure, but also forms the charge transport layer of the second passivated contact structure. This increases the contact area between the second passivated contact structure and the silicon substrate, which helps to improve the transport efficiency of charges of different polarities, thereby improving the photoelectric conversion efficiency of the battery.

[0031] In one alternative embodiment, forming a second passivated contact structure on the backlight surface includes:

[0032] An initial charge transport layer is formed on the entire back surface side of the substrate layer, and the initial charge transport layer covers the first passivation contact structure and the back surface exposed by the first passivation contact structure.

[0033] All initial charge transport layers located on the surface and periphery of the first passivation contact structure are removed to fully expose the first passivation contact structure and form a charge transport layer, forming a relatively isolated isolation space between the charge transport layer and the first passivation contact structure.

[0034] Beneficial effects: By completely separating the first passivation contact structure and the second passivation contact structure through the isolation space, the recombination of electrons and holes can be greatly reduced, thereby improving charge transport efficiency. Attached Figure Description

[0035] 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.

[0036] Figure 1 This is a schematic diagram of the base layer structure according to an embodiment of the present disclosure;

[0037] Figure 2 This is a schematic diagram of the structure after the initial tunneling oxide layer, the initial doped layer and the phosphosilicate glass layer are formed on the substrate layer according to an embodiment of this disclosure;

[0038] Figure 3 This is a schematic diagram of the structure after forming a tunneling oxide layer and a doped layer on the substrate layer according to an embodiment of the present disclosure;

[0039] Figure 4 This is a schematic diagram of the structure after the initial charge transport layer is formed according to an embodiment of this disclosure;

[0040] Figure 5 This is a schematic diagram of the structure after forming a charge transport layer by opening a first opening in the initial charge transport layer according to Embodiment 1 of this disclosure;

[0041] Figure 6 This is a schematic diagram of the structure after forming the first transparent conductive layer and the second transparent conductive layer in Embodiment 1 of this disclosure;

[0042] Figure 7 This is a schematic diagram of a hybrid passivated back contact solar cell according to Embodiment 1 of this disclosure;

[0043] Figure 8 This is another structural schematic diagram of the hybrid passivated back contact solar cell of Embodiment 1 of this disclosure;

[0044] Figure 9 This is a schematic flowchart of a method for fabricating a hybrid passivated back contact solar cell according to an embodiment of this disclosure;

[0045] Figure 10 This is a schematic diagram of the structure after the formation of the charge transport layer in Embodiment 2 of this disclosure;

[0046] Figure 11 This is a schematic diagram of the structure after forming the first transparent conductive layer and the second transparent conductive layer in Embodiment 2 of this disclosure;

[0047] Figure 12 This is a schematic diagram of a hybrid passivated back contact solar cell according to Embodiment 2 of this disclosure;

[0048] Figure 13 This is another structural schematic diagram of the hybrid passivated back contact solar cell of Embodiment 2 of this disclosure.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1. Substrate layer; 11. Light-receiving surface; 12. Backlight-receiving surface; 121. n-region; 122. p-region; 2. First passivation contact structure; 21. Tunneling oxide layer; 21a. Initial tunneling oxide layer; 22. Doped layer; 22a. Initial doped layer; 23. First transparent conductive layer; 3. Second passivation contact structure; 31. Charge transport layer; 31a. Initial charge transport layer; 311. First opening; 32. Second transparent conductive layer; 33. Interface passivation layer; 4. First electrode; 5. Second electrode; 6. Isolation space; 7. Passivation antireflection layer; 8. Phosphosilicate glass layer; 9. Second opening. Detailed Implementation

[0051] 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.

[0052] Among related technologies, novel solar cells formed by combining back-contact solar cells (i.e., BC cells) with other types of solar cells have attracted much attention. For example, BC cell technology can be superimposed with TOPCon cell technology, HJT cell technology, etc., to form high-efficiency cell technologies such as TBC and HBC. In TBC cells, the passivation and contact performance of p-poly are weaker than those of n-poly. The p-poly process is limited by the current technology level and cannot be significantly optimized. Similarly, HBC cells are still underdeveloped in terms of cell structure and fabrication process due to the requirements of low-temperature processing. Therefore, there is an urgent need for a new type of back-contact solar cell that can ensure the efficient passivation and contact performance of the p-type region structure, thereby improving the photoelectric conversion efficiency of the cell.

[0053] Example 1

[0054] Based on this, refer to Figures 1 to 8This embodiment provides a hybrid passivated back contact solar cell, including: a substrate layer 1, a first passivated contact structure 2, a second passivated contact structure 3, a first electrode 4, and a second electrode 5. The substrate layer 1 includes a light-receiving surface 11 and a back-lighting surface 12 disposed opposite to each other. The first passivated contact structure 2 includes a tunneling oxide layer 21 and a doped layer 22 stacked together. The tunneling oxide layer 21 is disposed on a portion of the back-lighting surface 12, and the doped layer 22 is disposed on the tunneling oxide layer 21. The second passivated contact structure 3 includes a charge transport layer 31, which at least covers the exposed back-lighting surface 12 of the first passivated contact structure 2. The first passivated contact structure 2 and the second passivated contact structure 3 have opposite conductivity types. The first electrode 4 is connected to the doped layer 22, and the second electrode 5 is connected to the charge transport layer 31.

[0055] Specifically, the substrate 1 is typically a silicon substrate. For ease of description, the backlight surface 12 of the substrate 1 is schematically divided into an n-region 121 and a p-region 122. See [link to documentation]. Figure 3 In this embodiment, a first passivation contact structure 2 is provided in the n-region 121. The first passivation contact structure 2 adopts the passivation contact structure of TOPCon batteries. The tunneling oxide layer 21 is ultrathin silicon oxide. In this embodiment, the doped layer 22 is a polycrystalline silicon layer after phosphorus diffusion. That is, the conductivity type of the first passivation contact structure 2 is n-type. A second passivation contact structure 3 is provided in the p-region 122. The second passivation contact structure 3 adopts the passivation contact structure of perovskite thin-film batteries. In this embodiment, the charge transport layer 31 is specifically a hole transport layer. That is, the conductivity type of the second passivation contact structure 3 is p-type. The material of the charge transport layer 31 can be polytriarylamine (PTAA), 2,2',7,7'-tetrakis[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Sprio-OMeTAD), nickel oxide (NiO). x Materials such as ) are used. The first electrode 4 is connected to the n-type first passivation contact structure 2, and the second electrode 5 is connected to the p-type second passivation contact structure 3 to achieve current extraction.

[0056] In summary, the hybrid passivated back-contact solar cell of this embodiment combines back-contact cell technology, TOPCon cell technology, and perovskite cell technology. The n-region 121 of the cell's back surface 12 adopts a first passivation contact structure 2 combining a tunneling oxide layer 21 and a polycrystalline silicon doped layer 22, while the p-region 122 adopts a second passivation contact structure 3, specifically a hole transport layer, from the charge transport layer 31 of a perovskite cell. This forms a hybrid passivated back-contact solar cell. This hybrid passivated back-contact solar cell solves the problem of thin p-poly silicon in traditional TBC cells. The problem of poor film performance was addressed by achieving efficient passivation across the entire region. On the other hand, compared with the passivation contact method of tunneling oxide layer and p-poly in TOPCon cells, and the passivation contact method of intrinsic amorphous silicon / boron-doped amorphous silicon in heterojunction cells, the passivation contact method of hole transport layer in perovskite cells in this embodiment can not only effectively reduce the carrier recombination efficiency on the p-region 122 surface, but also has a simpler and lower cost fabrication process, which is more conducive to obtaining a high-quality hybrid passivation structure, thereby obtaining a hybrid passivated back contact solar cell with superior photoelectric conversion efficiency.

[0057] In one embodiment, the absolute value of the work function of the charge transport layer 31 is less than or equal to 6 eV, and the thickness of the charge transport layer 31 is greater than 100 nm.

[0058] Specifically, the work function is typically negative, meaning the work function of the charge transport layer 31 in this embodiment ranges from -6 eV to 0. Since the magnitude of the work function of the charge transport layer 31 directly affects the contact barrier height with the crystalline silicon substrate 1, a higher contact barrier height makes carrier transport more difficult. When the charge transport layer 31, i.e., the hole transport layer in this embodiment, covers the substrate 1, its work function (equivalent to the energy level) will undergo band bending with the Fermi level of the silicon substrate 1. In this embodiment, the absolute value of the work function of the hole transport layer is limited to less than or equal to 6 eV, which effectively reduces the contact barrier height, i.e., reduces the band bending height. This allows hole carriers at the top of the valence band in the silicon energy level to be transported more effectively to the hole transport layer, effectively ensuring the hole carrier transport efficiency. On the other hand, unlike the hole transport layer of about tens of nanometers in conventional perovskite solar cells, in this embodiment, since the hole transport layer needs to cover the substrate layer 1 with a textured surface, in order to effectively cover the substrate layer 1 with such a textured surface, in this embodiment, the thickness of the charge transport layer 31, that is, the hole transport layer, is limited to greater than 100 nm, which improves the reliability of the charge transport layer 31 on the substrate layer 1.

[0059] like Figure 7As shown, based on the above embodiments, in one embodiment, the first passivation contact structure 2 may further include a first transparent conductive layer 23 disposed on the doped layer 22, and the first electrode 4 disposed on the first transparent conductive layer 23; the second passivation contact structure 3 may further include a second transparent conductive layer 32 disposed on the charge transport layer 31, and the second electrode 5 disposed on the second transparent conductive layer 32; the first transparent conductive layer 23 and the second transparent conductive layer 32 are disposed at intervals.

[0060] Specifically, the first transparent conductive layer 23 and the second transparent conductive layer 32 can be materials such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), graphene, carbon nanotubes, and metal mesh, which have good light transmittance and conductivity, and can effectively conduct the current in the doped layer 22 and the charge transport layer 31 respectively, thereby further improving the photoelectric conversion efficiency of the battery.

[0061] In an optional embodiment, the charge transport layer 31 of the second passivation contact structure 3 covers the surface of the first passivation contact structure 2 and the backlight surface 12 not covered by the first passivation contact structure 2; the charge transport layer 31 has an opening that exposes a portion of the doped layer 22; the first transparent conductive layer 23 covers the opening to connect with the doped layer 22.

[0062] like Figure 7 As shown, the first passivation contact structure 2 covers a portion of the backlight surface 12, specifically the n-region 121 of the backlight surface 12, enabling electron flow conduction. The charge transport layer 31 of the second passivation contact structure 3, while covering the p-region 122 of the backlight surface to achieve charge conduction, also extends to cover a portion of the surface of the first passivation contact structure 2. The charge transport layer 31 on the surface of the first passivation contact structure 2 forms a first opening 311 exposing a portion of the doped layer 22, allowing the first electrode 4 or the first transparent conductive layer 23 to connect to the doped layer 22 through the first opening 311, thus achieving electrical connection. This increases the contact area between the second passivation contact structure 3 and the silicon substrate, helping to improve the transport efficiency of charges of different polarities, thereby improving the photoelectric conversion efficiency of the battery.

[0063] like Figure 8As shown, in one embodiment, the second passivated contact structure 3 further includes an interface passivation layer 33 disposed between the charge transport layer 31 and the substrate layer 1. Specifically, the interface passivation layer 33 is first applied to the surface of the p-region 122 on the back surface 12 of the substrate layer 1, and then the charge transport layer 31 is formed on the interface passivation layer 33, thereby forming the second passivated contact structure 3. In this embodiment, the interface passivation layer 33 is disposed between the charge transport layer 31 and the substrate layer 1 to further passivate the surface of the p-region 122, which helps to reduce interface defects and suppress non-radiative recombination; it can also improve the band matching of the interface, block electrons, promote the separation of photogenerated carriers and subsequent transport efficiency; and improve the connection stability between the charge transport layer 31 and the substrate layer 1, thereby improving the overall stability of the second passivated contact structure 3 and even the battery.

[0064] Specifically, the aforementioned interface passivation layer 33 includes one or more of the following: a silicon oxide layer, an aluminum oxide layer, and an intrinsic amorphous silicon layer. The interface passivation layer 33 can be made from various inorganic materials. When the charge transport layer 31 uses an organic material such as Sprio-OMeTAD, the combination of the two can achieve composite passivation of inorganic and organic materials in the p-region 122, further reducing surface carrier recombination in the p-region 122 without significantly increasing the overall process steps and manufacturing cost. This provides more structural possibilities for hybrid passivation back-contact solar cells, enhances their applicability, and improves economic efficiency.

[0065] Furthermore, given that the charge transport layer 31 already possesses certain passivation properties, the interface passivation layer 33 should primarily consider carrier selective transport performance. Therefore, the thickness of the aforementioned interface passivation layer 33 is thinner than the inorganic interface passivation layer in conventional TOPCon and HJT batteries, serving as an auxiliary passivation repair layer. If the interface passivation layer 33 is thicker, it will reduce the probability of carriers in the substrate layer 1 passing through the interface passivation layer 33, thus reducing the likelihood of carriers being collected by the charge transport layer 31. Taking a TOPCon battery as an example, the thickness of a conventional tunneling oxide layer is 1~2 nm, but the thickness of the interface passivation layer 33 in this disclosure is less than or equal to 1 nm.

[0066] In one embodiment, the hybrid passivated back contact solar cell may further include a passivation antireflection layer 7 disposed on the light-receiving surface 11 of the substrate layer 1.

[0067] like Figure 7 and Figure 8 As shown, the light-receiving surface 11 of the silicon substrate in this embodiment has a textured structure to increase light trapping on the front side. On this basis, a passivation antireflection layer 7 is formed on the light-receiving surface 11. The passivation antireflection layer 7 can be made of materials such as amorphous silicon or silicon nitride, which helps to further reduce optical losses on the light-receiving surface 11 and improve the power generation efficiency of the battery.

[0068] refer to Figures 1 to 9 This embodiment also provides a method for fabricating a hybrid passivated back contact solar cell, used to fabricate the aforementioned hybrid passivated back contact solar cell. Figure 9 The diagram below illustrates the process of this preparation method, which specifically includes the following steps:

[0069] Step S901, a substrate layer 1 is provided, the substrate layer 1 including a light-receiving surface 11 and a backlight surface 12 disposed opposite to each other.

[0070] refer to Figure 1 In this embodiment, the substrate 1 is a silicon substrate, which is formed by polishing the silicon wafer on both sides to create a silicon substrate for preparing solar cells.

[0071] In step S902, a first passivation contact structure 2 is formed on the backlight surface 12. The first passivation contact structure 2 includes a tunneling oxide layer 21 and a doped layer 22 stacked together. The tunneling oxide layer 21 is disposed on a portion of the backlight surface 12, and the doped layer 22 is disposed on the tunneling oxide layer 21.

[0072] refer to Figure 2 First, an initial tunneling oxide layer 21a and an initial polysilicon layer are sequentially deposited on the backlight surface 12. Then, the initial polysilicon layer undergoes phosphorus diffusion treatment to obtain an initial doped layer 22a and a phosphorosilicate glass layer 8 (i.e., a PSG layer). Next, the initial doped layer 22a, the initial tunneling oxide layer 21a, and all of the phosphorosilicate glass layer 8 located in the p-region 122 of the substrate are locally removed using a laser, forming the tunneling oxide layer 21 and the doped layer 22 of the first passivation contact structure 2, exposing the surface of the p-region 122 on the backlight surface 12 of the silicon substrate. It is known that this surface also has a textured surface, such as... Figure 3 As shown, this part of the structure will be omitted in the following diagrams for ease of illustration.

[0073] In step S903, a second passivation contact structure 3 is formed on the backlight surface 12. The second passivation contact structure 3 includes a charge transport layer 31, which at least covers the backlight surface 12 exposed by the first passivation contact structure 2. The first passivation contact structure 2 and the second passivation contact structure 3 have opposite conductivity types.

[0074] This step S903 specifically includes the following steps:

[0075] In step S9031a, an initial charge transport layer 31a is formed on the entire backlight surface 12 side of the substrate layer 1, and the initial charge transport layer 31a covers the first passivation contact structure 2 and the exposed backlight surface 12 of the first passivation contact structure 2.

[0076] For example, an initial charge transport layer 31a can be deposited on the entire back surface 12 side of the substrate 1 using plasma chemical vapor deposition, covering the entire first passivation contact structure 2 and the exposed back surface 12 surface of the first passivation contact structure 2, such as... Figure 4 As shown.

[0077] Step S9032a: Remove part of the initial charge transport layer 31a located on the first passivation contact structure 2 to form an opening that exposes the doped layer 22.

[0078] For example, the initial charge transport layer 31a on the surface of the first passivated contact structure 2 can be patterned and grooved using methods such as laser, photolithography, or etching to form a first opening 311 exposing a portion of the doped layer 22 and a charge transport layer 31 connected to the p-region 122 of the substrate layer, such as... Figure 5 As shown, the first opening 311 provides a channel for the subsequent connection of the first electrode 4 or the first transparent conductive layer 23 to the doped layer 22.

[0079] In step S904, a first electrode 4 and a second electrode 5 are formed. The first electrode 4 is connected to the doped layer 22, and the second electrode 5 is connected to the charge transport layer 31.

[0080] For example, electrode paste can be printed on the charge transport layer 31 corresponding to the first opening 311 and the p-region 122 using methods such as screen printing, followed by sintering to finally form a first electrode 4 connected to the doped layer 22 and a second electrode 5 connected to the charge transport layer 31. (Refer to...) Figure 7 As shown.

[0081] In the preparation method of the hybrid passivated back contact solar cell in this embodiment, firstly, a tunneling oxide layer 21 and a doped layer 22 are formed in the n region 121 of the back surface 12 of the substrate layer 1 using TOPCon cell-related structures to achieve efficient electron transport; then, a hole transport layer is formed in the p region 122 of the back surface using perovskite cell-related structures to achieve efficient hole transport. Different types of passivated contact structures are formed on one side of the back surface 12 of the cell, resulting in good thin film performance in different polarity regions of the formed hybrid passivated back contact solar cell. The preparation process is simple, and the cell's photoelectric conversion efficiency is improved while also being economically efficient.

[0082] In one embodiment, after step S902 of forming the first passivation contact structure 2 on the backlight surface 12 and before step S903 of forming the second passivation contact structure 3 on the backlight surface 12, the method further includes:

[0083] The battery structure having a substrate layer 1 and a first passivation contact structure 2 is cleaned and texturized to form a textured structure on the light-receiving surface 11 and the backlight surface 12 not covered by the first passivation contact structure 2.

[0084] A passivation and antireflection layer 7 is deposited on the light-receiving surface 11 of the base layer 1.

[0085] Specifically, the cleaning process removes impurities from the battery surface, and the texturing process creates a textured surface to increase light trapping. See [link to relevant documentation]. Figure 3 The textured structure of the light-receiving surface 11 and the passivation antireflection layer 7 are superimposed to maximize the utilization of sunlight and improve power generation efficiency. The textured structure of the back surface 12 helps to improve the structural stability of the charge transport layer 31 and reduce interface recombination.

[0086] See Figure 6 After step S903 of forming the second passivation contact structure 3 on the backlight surface 12, and before step S904 of forming the first electrode 4 and the second electrode 5, the method further includes:

[0087] An initial transparent conductive layer is deposited on the entire back surface 12 side of the substrate 1;

[0088] The initial transparent conductive layer is partially removed to form a second opening 9 that is misaligned with the first opening 311, so as to obtain a first transparent conductive layer 23 connected to the doped layer 22 through the first opening 311 and a second transparent conductive layer 32 connected to the charge transport layer 31.

[0089] The first transparent conductive layer 23 and the second transparent conductive layer 32 are formed by deposition on the whole surface and then local removal. The high material consistency helps to ensure the charge discharge performance of the first passivated contact structure 2 and the second passivated contact structure 3, thereby improving power generation efficiency and battery life.

[0090] Example 2

[0091] refer to Figures 10 to 13 The difference between this embodiment and Embodiment 1 is that: First, an isolation space 6 is formed between the first passivation contact structure 2 and the second passivation contact structure 3. Secondly, correspondingly, the step S903 of forming the second passivation contact structure 3 on the backlight surface 12 specifically includes the following steps:

[0092] Step S9031b: An initial charge transport layer 31a is formed on the entire backlight surface 12 side of the substrate layer 1. The initial charge transport layer 31a covers the first passivation contact structure 2 and the backlight surface 12 exposed by the first passivation contact structure 2.

[0093] Step S1032b: Remove all initial charge transport layers 31a located on the surface and periphery of the first passivation contact structure 2 to fully expose the first passivation contact structure 2 and form a charge transport layer 31. A relatively isolated isolation space 6 is formed between the charge transport layer 31 and the first passivation contact structure 2, such as... Figure 10 As shown.

[0094] On the aforementioned backlight surface, the first passivated contact structure 2 of the n-region 121 and the second passivated contact structure 3 of the p-region 122 are completely separated by the isolation space 6, forming a distinct isolation region between different polarity regions. This effectively blocks the p-region 122 and the n-region 121 to reduce the risk of short-circuit leakage, significantly reduces the recombination of electrons and holes, and also reduces the parasitic absorption of the charge transport layer 31, thereby improving charge transport efficiency and further enhancing battery performance. Of course, it is also possible to form the isolation space 6 through photolithography or etching to simplify the fabrication process.

[0095] See Figures 11 to 13 In one embodiment, it can also have the same structure as in Embodiment 1, such as the interface passivation layer 33, the passivation antireflection layer 7, the first transparent conductive layer 23, and the second transparent conductive layer 32. The tunneling oxide layer 21, the doped layer 22, and the first transparent conductive layer 23 of the first passivation contact structure 2 are formed in the same shape, that is, their projections on the substrate layer 1 coincide. The interface passivation layer 33, the charge transport layer 31, and the second transparent conductive layer 32 of the second passivation contact structure 3 are formed in the same shape. The rest will not be described in detail here.

[0096] In summary, the batteries corresponding to Embodiment 1 and Embodiment 2 are obtained. In both Embodiment 1 and Embodiment 2, the first passivation contact structure 2 located in the n region 121 includes a tunneling oxide layer 21, a doped layer 22, and a first transparent conductive layer 23. The second passivation contact structure 3 in the p region 122 includes an interface passivation layer 33, a charge transport layer 31 (specifically a hole transport layer), and a second transparent conductive layer 32. The battery structure of Embodiment 1 is as follows: Figure 8 As shown, the battery structure of Example 2 is as follows. Figure 13 As shown.

[0097] In addition, Comparative Example 1 and Comparative Example 2 were selected. Both Comparative Example 1 and Comparative Example 2 adopted the same passivation contact structure in the p region as the cells of Example 1 and Example 2. However, Comparative Example 1 adopted a tunneling oxide layer, a p-type doped polycrystalline silicon layer, and a transparent conductive layer in the p region as a passivation contact structure in the form of a conventional TOPCon cell. Comparative Example 2 adopted an intrinsic amorphous silicon layer, a p-type doped amorphous silicon layer, and a transparent conductive layer in the p region as a passivation contact structure in the form of an HJT cell.

[0098] Based on this, the batteries of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were subjected to electrical performance tests, and the data shown in the table below were obtained:

[0099]

[0100] As shown in the table above, the batteries of Example 1 and Example 2 have similar conversion efficiencies ( η ), open circuit voltage ( Voc ), short-circuit current density ( J sc ) and fill factor ( FF In terms of various current performance parameters, it is superior to Comparative Example 1 and Comparative Example 2. That is, the second passivated contact structure 3 used in p region 122 of Embodiment 1 and Embodiment 2 can effectively improve the cell efficiency of back contact solar cells.

[0101] Specifically, firstly, for the battery of Example 1, a low-cost perovskite battery hole transport layer 31 is used as the charge transport layer 31 in the p-region 122 to achieve passivation and transport of charge carriers. The hole transport layer itself has certain passivation performance, and it is also prepared using a low-temperature process, avoiding secondary high-temperature effects on the substrate 1 and ensuring the performance of the substrate 1. In addition, the hole transport layer is combined with a high-quality inorganic interface passivation layer 33, making the passivation and transport performance of charge carriers in the p-region much higher than that of Comparative Example 1 and Comparative Example 2. Secondly, for the battery of Example 2, in order to reduce the parasitic absorption of the hole transport layer and effectively block the p-region 122 and n-region 121 to avoid short circuit leakage, a clear isolation space 6 is formed between different polarity regions of the backlight surface 12. Compared with Example 1, the optical performance of the battery is significantly improved. However, due to the presence of the isolation space 6, the backlight surface 12 of the battery is not fully passivated, resulting in a lower open-circuit voltage than that of Example 1. However, the overall electrical performance is not much different from that of Example 1, but it is still significantly higher than that of Comparative Example 1 and Comparative Example 2. For Comparative Example 1, the poor passivation and contact performance of p-poly significantly reduced battery performance, resulting in the lowest battery efficiency. For Comparative Example 2, although the p-region adopted a passivation contact form of boron-doped amorphous silicon, which further improved the performance compared to p-poly and resulted in higher electrical performance than Comparative Example 1, the overall equipment investment cost was high, and the passivation performance of the boron-doped amorphous silicon layer was still lower than that of the batteries in Examples 1 and 2, resulting in lower electrical performance than in Examples 1 and 2.

[0102] Further functional descriptions of the above structures are the same as those of the corresponding embodiments described above, and will not be repeated here.

[0103] 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.

[0104] 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 hybrid passivated 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 first passivated contact structure includes a tunneling oxide layer and a doped layer stacked together, wherein the tunneling oxide layer is disposed on a portion of the backlight surface, and the doped layer is disposed on the tunneling oxide layer; The second passivation contact structure has a p-type conductivity and includes a charge transport layer, which is a hole transport layer of a perovskite solar cell, and at least covers the backlight surface exposed by the first passivation contact structure; the first passivation contact structure has the opposite conductivity type to the second passivation contact structure. A first electrode and a second electrode, wherein the first electrode is connected to the doped layer and the second electrode is connected to the charge transport layer.

2. The hybrid passivated back contact solar cell according to claim 1, characterized in that, The absolute value of the work function of the charge transport layer is less than or equal to 6 eV, and the thickness of the charge transport layer is greater than 100 nm.

3. The hybrid passivated back contact solar cell according to claim 1, characterized in that, The first passivated contact structure further includes a first transparent conductive layer disposed on the doped layer, and the first electrode is disposed on the first transparent conductive layer; The second passivated contact structure further includes a second transparent conductive layer disposed on the charge transport layer, and the second electrode is disposed on the second transparent conductive layer; the first transparent conductive layer and the second transparent conductive layer are disposed at intervals.

4. The hybrid passivated back contact solar cell according to claim 3, characterized in that, The charge transport layer of the second passivated contact structure covers the surface of the first passivated contact structure and the backlight surface not covered by the first passivated contact structure; the charge transport layer has an opening that exposes a portion of the doped layer; The first transparent conductive layer covers the opening to connect with the doped layer.

5. The hybrid passivated back contact solar cell according to claim 3, characterized in that, An isolation space is formed between the first passivated contact structure and the second passivated contact structure.

6. The hybrid passivated back contact solar cell according to claim 1, characterized in that, The second passivated contact structure further includes an interface passivation layer disposed between the charge transport layer and the substrate layer.

7. The hybrid passivated back contact solar cell according to claim 6, characterized in that, The interface passivation layer includes one or more of the following: silicon oxide layer, aluminum oxide layer, and intrinsic amorphous silicon layer.

8. The hybrid passivated back contact solar cell according to claim 1, characterized in that, Also includes: A passivation antireflection layer is disposed on the light-receiving surface of the substrate layer.

9. A method for fabricating a hybrid passivated back-contact solar cell, used to fabricate the hybrid passivated back-contact solar cell according to any one of claims 1-8, characterized in that, include: A substrate layer is provided, the substrate layer comprising a light-receiving surface and a backlight surface disposed opposite to each other; A first passivation contact structure is formed on the backlight surface. The first passivation contact structure includes a tunneling oxide layer and a doped layer stacked together. The tunneling oxide layer is disposed on a portion of the backlight surface, and the doped layer is disposed on the tunneling oxide layer. A second passivation contact structure is formed on the backlight surface. The second passivation contact structure has a p-type conductivity and includes a charge transport layer, which is a hole transport layer of a perovskite solar cell. The charge transport layer at least covers the backlight surface exposed by the first passivation contact structure. The conductivity types of the first passivation contact structure and the second passivation contact structure are opposite. A first electrode and a second electrode are formed, wherein the first electrode is connected to the doped layer and the second electrode is connected to the charge transport layer.

10. The method for fabricating a hybrid passivated back contact solar cell according to claim 9, characterized in that, The formation of the second passivated contact structure on the backlight surface includes: An initial charge transport layer is formed on the entire back surface side of the substrate layer, and the initial charge transport layer covers the first passivation contact structure and the back surface exposed by the first passivation contact structure. A portion of the initial charge transport layer located on the first passivated contact structure is removed to form an opening exposing the doped layer.

11. The method for fabricating a hybrid passivated back contact solar cell according to claim 9, characterized in that, The formation of the second passivated contact structure on the backlight surface includes: An initial charge transport layer is formed on the entire back surface side of the substrate layer, and the initial charge transport layer covers the first passivation contact structure and the back surface exposed by the first passivation contact structure. All of the initial charge transport layer located on the surface and periphery of the first passivated contact structure is removed to fully expose the first passivated contact structure and form the charge transport layer, wherein a relatively isolated isolation space is formed between the charge transport layer and the first passivated contact structure.

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