Hybrid passivation back contact solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, and discloses a hybrid passivation back contact solar cell and a preparation method thereof. The cell comprises a substrate layer, a first passivation contact structure, a second passivation contact structure, a first electrode and a second electrode, wherein the substrate layer comprises a light receiving surface and a backlight surface which are opposite to each other; the first passivation contact structure comprises a tunneling oxide layer and a doping layer which are stacked; the second passivation contact structure comprises a charge transport layer which at least covers the exposed backlight surface of the first passivation contact structure; the conduction types of the first passivation contact structure and the second passivation contact structure are opposite; the first electrode is connected with the doping layer, and the second electrode is connected with the charge transmission layer. In the invention, the n region of the backlight surface adopts the first passivation contact structure formed by combining the tunneling oxide layer and the polycrystalline silicon doping layer, and the p region adopts the charge transport layer of the perovskite cell, so that the mixed passivation back contact cell is formed, the problem of poor passivation contact performance of the p region of the TBC cell is solved, the process is simpler, and the cost is low.

Description

Technical Field

[0001] The present disclosure relates to the technical field of solar cells, and in particular to a hybrid passivated back contact solar cell and a preparation method thereof. Background Art

[0002] Back-contact solar cells (BC cells for short) are a technology that transfers all positive and negative electrodes to the back of the cell. There are no grid lines blocking the front, which can effectively improve light absorption efficiency and reduce current loss. With the continuous development of solar cell technology, hybrid back-contact cells that combine back-contact solar cell technology with other types of solar cell technology have received widespread attention. For example, the tunneling oxide passivated back contact cell (TBC cell for short), which is formed by combining the tunneling oxide passivated contact solar cell (TOPCon cell for short) technology with the BC cell technology, applies the tunneling oxide passivated contact structure of the TOPCon cell to the back contact structure. All electrodes are prepared on the back of the cell. While retaining the high current advantage of the BC cell's front side, it also further improves the cell's open circuit voltage and photoelectric conversion efficiency.

[0003] In TBC cells, the p-type doped layer (p-poly) on the back is weaker than the n-type doped layer (n-poly) in terms of both passivation and contact performance. Therefore, the performance of the p-type doped layer directly determines the photovoltaic conversion efficiency of the cell, but it is difficult to achieve significant optimization on the process side. To this end, the industry has begun to adopt heterojunction passivation contact technology with intrinsic amorphous silicon / p-type doped amorphous silicon to replace the traditional p-type doped layer, thereby forming a mixed (or hybrid) passivated back-contact solar cell. However, this heterojunction passivation contact technology generally requires a low-temperature process to achieve the preparation of high-quality amorphous silicon thin films, which is difficult and costly, affecting the photovoltaic conversion efficiency and performance of the cell. Summary of the Invention

[0004] In view of this, the present disclosure provides a hybrid passivated back-contact solar cell and a preparation method thereof to solve the problem that the optimization process of the back film layer of the existing back-contact solar cell is difficult and costly, which affects the photoelectric conversion efficiency of the cell.

[0005] In the first aspect, the present disclosure provides a hybrid passivated back-contact solar cell, comprising: a base layer, a first passivation contact structure, a second passivation contact structure, a first electrode, and a second electrode, wherein the base layer comprises a light-receiving surface and a backlight surface arranged opposite to each other; the first passivation contact structure comprises a tunneling oxide layer and a doping layer arranged in a stacked manner, the tunneling oxide layer is arranged on a portion of the backlight surface, and the doping layer is arranged on the tunneling oxide layer; the second passivation contact structure comprises a charge transfer layer, and the charge transfer layer at least covers the backlight surface exposed by the first passivation contact structure; the conductivity type of the first passivation contact structure is opposite to that of the second passivation contact structure; the first electrode is connected to the doping layer, and the second electrode is connected to the charge transfer layer.

[0006] Beneficial effects: The hybrid passivated back contact solar cell disclosed in the present invention combines back contact cell technology, TOPCon cell technology and perovskite cell technology. The n-region on the backlight side of the cell corresponds to a first passivation contact structure combining a tunneling oxide layer and a polysilicon doped layer, and the p-region corresponds to a second passivation contact structure of a charge transport layer of a perovskite cell, specifically a hole transport layer, thereby forming a hybrid passivated back contact solar cell. This hybrid passivated back contact solar cell, on the one hand, solves the problem of poor performance of the p-poly thin film of traditional TBC cells; on the other hand, compared with the passivation contact method of 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 the hole transport layer of the perovskite cell has a simpler thin film process and lower cost, which is more conducive to obtaining a high-quality hybrid passivation structure, thereby obtaining a hybrid passivated back contact solar cell with excellent photoelectric conversion efficiency.

[0007] In an optional embodiment, 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 6 eV or less effectively reduces the contact barrier height, and therefore the band bending height. This allows hole carriers at the top of the silicon valence band to be more efficiently transported to the hole transport layer, effectively ensuring hole carrier transport efficiency. The thickness of the charge transport layer, specifically the hole transport layer, is limited to greater than 100 nm to effectively cover the base layer with a suede structure, improving the reliability of the charge transport layer on the base layer.

[0009] In an optional embodiment, the first passivation contact structure also includes a first transparent conductive layer arranged on the doping layer, and the first electrode is arranged on the first transparent conductive layer; the second passivation contact structure also includes a second transparent conductive layer arranged on the charge transfer layer, and the second electrode is arranged on the second transparent conductive layer; the first transparent conductive layer and the second transparent conductive layer are arranged at intervals.

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

[0011] In an optional embodiment, the charge transfer layer of the second passivation contact structure covers the surface of the first passivation contact structure and the backlight surface not covered by the first passivation contact structure; the charge transfer layer has an opening, and the opening exposes a portion of the doped layer; the first transparent conductive layer covers the opening to be connected to the doped layer.

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

[0013] In an optional embodiment, an isolation space is formed between the first passivation contact structure and the second passivation contact structure.

[0014] Beneficial effects: The first passivation contact structure and the second passivation contact structure are completely isolated by the isolation space, the preparation is simple, and the recombination of electrons and holes is greatly reduced, thereby improving the charge transfer efficiency.

[0015] In an optional embodiment, the second passivation contact structure further includes: an interface passivation layer disposed between the charge transport layer and the base layer.

[0016] Beneficial effects: Providing an interface passivation layer between the charge transport layer and the substrate layer helps reduce interface defects and inhibit non-radiative recombination; it can also improve the energy 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 an optional embodiment, the interface passivation layer includes: one or more of a silicon oxide layer, an aluminum oxide layer, and an intrinsic amorphous silicon layer.

[0018] Beneficial effects: A variety of materials can be used for the interface passivation layer, providing more structural possibilities for hybrid passivated back-contact solar cells, expanding the scope of application and improving economic benefits.

[0019] In an optional embodiment, a passivation anti-reflection layer is further included, which is arranged on the light-receiving surface of the base layer.

[0020] Beneficial effect: The formation of a passivation anti-reflection layer on the light-receiving surface helps to further reduce the optical loss of the light-receiving surface and improve the power generation efficiency of the battery.

[0021] In a second aspect, the present disclosure further provides a method for preparing a hybrid passivated back contact solar cell, which is used to prepare the above-mentioned hybrid passivated back contact solar cell, comprising: Providing a base layer, the base layer comprising a light-receiving surface and a backlight surface that are oppositely disposed; forming a first passivation contact structure on the backlight surface, the first passivation contact structure comprising a tunneling oxide layer and a doping layer stacked together, the tunneling oxide layer being disposed on a portion of the backlight surface, and the doping layer being disposed on the tunneling oxide layer; forming a second passivation contact structure on the backlight surface, the second passivation contact structure including a charge transfer layer, the charge transfer layer at least covering the backlight surface exposed by the first passivation contact structure; the first passivation contact structure and the second passivation contact structure have opposite conductivity types; A first electrode and a second electrode are formed, wherein the first electrode is connected to the doping layer, and the second electrode is connected to the charge transport layer.

[0022] Beneficial effect: In the preparation method of the hybrid passivated back contact cell disclosed in the present invention, first, a TOPCon cell-related structure is applied to the n-region of the backlight side of the substrate layer to form a tunneling oxide layer and a doping layer to achieve efficient transmission of electrons; then, a perovskite cell-related structure is applied to the p-region of the backlight side to form a hole transport layer to achieve efficient transmission of holes, and different types of passivation contact structures are formed on the backlight side of the cell, so that the formed hybrid passivated back contact solar cell has good thin film performance in different polarity regions, a simple preparation process, and high economic benefits while improving the photoelectric conversion efficiency of the cell.

[0023] In an optional embodiment, forming a second passivation contact structure on the backlight surface includes: forming an initial charge transport layer on the entire backlight side of the substrate layer, wherein the initial charge transport layer covers the first passivation contact structure and the backlight side exposed by the first passivation contact structure; A portion of the initial charge transport layer located on the first passivation contact structure is removed to form an opening exposing the doped layer.

[0024] Beneficial effect: After the entire surface is covered with the initial charge transfer layer, a first opening is opened on the first passivation contact structure by local removal methods such as laser, which can not only provide a current extraction channel for the first passivation contact structure, but also form a charge transfer layer for the second passivation contact structure, increasing the contact area between the second passivation contact structure and the silicon substrate, which helps to improve the transmission efficiency of charges of different polarities, and thus improve the photoelectric conversion efficiency of the battery.

[0025] In an optional embodiment, forming a second passivation contact structure on the backlight surface includes: forming an initial charge transport layer on the entire backlight side of the substrate layer, wherein the initial charge transport layer covers the first passivation contact structure and the backlight side exposed by the first passivation contact structure; All initial charge transfer layers on the surface and surrounding side of the first passivation contact structure are removed to completely expose the first passivation contact structure and form a charge transfer layer, with a relatively isolated isolation space formed between the charge transfer layer and the first passivation contact structure.

[0026] Beneficial effect: The first passivation contact structure and the second passivation contact structure are completely isolated by the isolation space, which can greatly reduce the recombination of electrons and holes, thereby improving the charge transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 is a schematic structural diagram of a base layer according to an embodiment of the present disclosure; Figure 2 is a schematic structural diagram of an embodiment of the present disclosure after an initial tunneling oxide layer, an initial doping layer, and a phosphosilicate glass layer are formed on a substrate layer; Figure 3 is a schematic structural diagram of an embodiment of the present disclosure after a tunneling oxide layer and a doping layer are formed on a base layer; Figure 4 is a schematic structural diagram of an embodiment of the present disclosure after forming an initial charge transport layer; Figure 5 1 is a schematic structural diagram of embodiment 1 of the present disclosure after a first opening is opened on the initial charge transport layer to form a charge transport layer; Figure 6 is a schematic structural diagram of embodiment 1 of the present disclosure after the first transparent conductive layer and the second transparent conductive layer are formed; Figure 7 1 is a schematic structural diagram of a hybrid passivated back contact solar cell according to Example 1 of the present disclosure; Figure 8 is another structural schematic diagram of a hybrid passivated back contact solar cell according to Example 1 of the present disclosure; Figure 9 1 is a schematic flow chart of a method for preparing a hybrid passivated back contact solar cell according to an embodiment of the present disclosure; Figure 10 is a schematic structural diagram of Example 2 of the present disclosure after the charge transport layer is formed; Figure 11 is a schematic structural diagram of embodiment 2 of the present disclosure after forming the first transparent conductive layer and the second transparent conductive layer; Figure 12 1 is a schematic structural diagram of a hybrid passivated back contact solar cell according to Example 2 of the present disclosure; Figure 13 This is another structural schematic diagram of the hybrid passivated back contact solar cell of Example 2 of the present disclosure.

[0029] Description of reference numerals: 1. Base layer; 11. Light-receiving surface; 12. Backlight surface; 121. n-region; 122. p-region; 2. First passivation contact structure; 21. Tunneling oxide layer; 21a. Initial tunneling oxide layer; 22. Doping layer; 22a. Initial doping layer; 23. First transparent conductive layer; 3. Second passivation contact structure; 31. Charge transfer layer; 31a. Initial charge transfer layer; 311. First opening; 32. Second transparent conductive layer; 33. Interface passivation layer; 4. First electrode; 5. Second electrode; 6. Isolation space; 7. Passivation anti-reflection layer; 8. Phosphorus silicon glass layer; 9. Second opening. DETAILED DESCRIPTION

[0030] The present disclosure will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are intended only to illustrate the present disclosure and are not intended to limit it. It should also be noted that, for ease of description, the drawings only illustrate some, but not all, structures relevant to the present disclosure. In the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present disclosure. The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present disclosure. These figures are not drawn to scale; certain details are exaggerated and may be omitted for clarity. The shapes, relative sizes, and positional relationships of the various regions and layers shown in the figures are merely illustrative and may vary in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs. In the context of the present 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 an intervening layer / element may exist between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element would be "below" the other layer / element.

[0031] Among related technologies, new types of solar cells, formed by combining back-contact solar cells (BC cells) with other types of solar cells, have attracted considerable attention. For example, BC cell technology can be combined with TOPCon cell technology and HJT cell technology to form high-efficiency cell technologies such as TBC and HBC. The passivation and contact performance of p-poly in TBC cells are weaker than those of n-poly, and significant optimization of p-poly is difficult due to current process limitations. Similarly, due to the low-temperature process requirements of HBC cells, the cell structure and fabrication process are still underdeveloped. Therefore, a new type of back-contact solar cell is urgently needed to ensure efficient passivation and contact performance in the p-type region structure, thereby improving the cell's photoelectric conversion efficiency.

[0032] Example 1 Based on this, reference Figures 1 to 8, this embodiment provides a hybrid passivation back contact solar cell, including: a base layer 1, a first passivation contact structure 2, a second passivation contact structure 3, a first electrode 4 and a second electrode 5, the base layer 1 includes a light-receiving surface 11 and a backlight surface 12 arranged opposite to each other; the first passivation contact structure 2 includes a tunneling oxide layer 21 and a doping layer 22 arranged in a stacked manner, the tunneling oxide layer 21 is arranged on a portion of the backlight surface 12, and the doping layer 22 is arranged on the tunneling oxide layer 21; the second passivation contact structure 3 includes a charge transfer layer 31, and the charge transfer layer 31 covers at least the backlight surface 12 exposed by the first passivation contact structure 2; the conductivity type of the first passivation contact structure 2 and the second passivation contact structure 3 are opposite; the first electrode 4 is connected to the doping layer 22, and the second electrode 5 is connected to the charge transfer layer 31.

[0033] Specifically, the base layer 1 is usually a silicon base. For ease of description, the backlight surface 12 of the base layer 1 is divided into an n-region 121 and a p-region 122 for schematic illustration. Figure 3 . In this embodiment, a first passivation contact structure 2 is provided in the n region 121. The first passivation contact structure 2 applies the passivation contact structure of the TOPCon battery, wherein the tunneling oxide layer 21 is ultra-thin silicon oxide. In this embodiment, the doping layer 22 is a polysilicon 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 applies the passivation contact structure in the perovskite thin film battery. The charge transport layer 31 of this embodiment 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 for short), 2,2',7,7'-tetrakis[n,n-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Sprio-OMeTAD for short), nickel oxide (NiO x 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 realize current extraction.

[0034] 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 backlight surface 12 of the cell corresponds to the first passivation contact structure 2 combining the tunneling oxide layer 21 and the polysilicon doping layer 22, and the p-region 122 corresponds to the charge transport layer 31 of the perovskite cell, specifically the second passivation contact structure 3 of the hole transport layer, thereby forming a hybrid passivated back contact solar cell. This hybrid passivated back contact solar cell solves the problem of the traditional TBC cell p-poly thin film. On the other hand, compared with the passivation contact mode of the tunneling oxide layer and p-poly in the TOPCon cell, and the passivation contact mode of the intrinsic amorphous silicon / boron-doped amorphous silicon in the heterojunction cell, the passivation contact mode of the hole transport layer of the perovskite cell is adopted in the p-region in this embodiment, which can not only effectively reduce the carrier recombination efficiency on the surface of the p-region 122, but also has a simpler preparation process and lower cost, and is more conducive to obtaining a high-quality hybrid passivation structure, thereby obtaining a hybrid passivation back contact solar cell with excellent photoelectric conversion efficiency.

[0035] 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.

[0036] Specifically, the work function is typically negative, meaning that the work function of the charge transport layer 31 of this embodiment actually ranges from -6 eV to 0. Since the work function of the charge transport layer 31 directly affects the subsequent contact barrier height with the crystalline silicon base layer 1, the greater the contact barrier height, the more difficult carrier transport becomes. When the charge transport layer 31, or the hole transport layer in this embodiment, covers the base layer 1, its work function (equal to its energy level) will undergo band bending with the Fermi level of the silicon in the base layer 1. This embodiment limits the absolute value of the work function of the hole transport layer to less than or equal to 6 eV, effectively reducing the contact barrier height, or the band bending height, allowing hole carriers at the top of the valence band in the silicon energy level to be more efficiently transported to the hole transport layer, effectively ensuring the transport efficiency of hole carriers. On the other hand, unlike the hole transport layer of about tens of nanometers in conventional perovskite cells, in this embodiment, since the hole transport layer needs to cover the base layer 1 with a velvet structure, in order to effectively cover the base layer 1 with a velvet structure, the charge transport layer 31 in this embodiment is specifically the hole transport layer, and its thickness is greater than 100 nm, which improves the reliability of the charge transport layer 31 on the base layer 1.

[0037] 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 arranged on the doping layer 22, and the first electrode 4 is arranged on the first transparent conductive layer 23; the second passivation contact structure 3 also includes a second transparent conductive layer 32 arranged on the charge transfer layer 31, and the second electrode 5 is arranged on the second transparent conductive layer 32; the first transparent conductive layer 23 and the second transparent conductive layer 32 are arranged at intervals.

[0038] Specifically, the first transparent conductive layer 23 and the second transparent conductive layer 32 can be made of materials such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), graphene, carbon nanotubes, metal grids, etc., which have good light transmittance and conductivity, and can effectively conduct the current in the doping layer 22 and the charge transfer layer 31 respectively, thereby further improving the photoelectric conversion efficiency of the battery.

[0039] In an optional embodiment, the charge transfer layer 31 of the above-mentioned 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 transfer layer 31 has an opening exposing a portion of the doped layer 22; the first transparent conductive layer 23 covers the opening to be connected to the doped layer 22.

[0040] 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, to achieve electron flow conduction. The charge transfer layer 31 of the second passivation contact structure 3 not only covers the p-region 122 of the backlight surface to achieve charge conduction, but also extends to cover a portion of the surface of the first passivation contact structure 2. The charge transfer layer 31 on the surface of the first passivation contact structure 2 is formed with a first opening 311 that exposes a portion of the doped layer 22, thereby allowing the first electrode 4 or the first transparent conductive layer 23 to connect to the doped layer 22 through the first opening 311 to achieve electrical connection. This approach increases the contact area between the second passivation contact structure 3 and the silicon substrate, helping to improve the transmission efficiency of charges of different polarities, thereby improving the photoelectric conversion efficiency of the battery.

[0041] like Figure 8As shown, in one embodiment, the second passivation contact structure 3 further includes: an interface passivation layer 33 disposed between the charge transport layer 31 and the substrate layer 1. That is, the surface of the p-region 122 of the backlight surface 12 of the substrate layer 1 is first covered with the interface passivation layer 33, and then the charge transport layer 31 is formed on the interface passivation layer 33, thereby forming the second passivation 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, helping to reduce interface defects and inhibit non-radiative recombination. It can also improve the energy band matching of the interface, block electrons, and promote the separation and subsequent transport efficiency of photogenerated carriers. It also improves the connection stability between the charge transport layer 31 and the substrate layer 1, thereby improving the overall stability of the second passivation contact structure 3 and even the battery.

[0042] Specifically, the aforementioned interface passivation layer 33 includes one or more of a silicon oxide layer, an aluminum oxide layer, and an intrinsic amorphous silicon layer. The interface passivation layer 33 can be made of any of the aforementioned inorganic materials. When the charge transport layer 31 utilizes an organic material such as Spiro-OMeTAD, the combination of the two can achieve composite passivation of the 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 costs. This provides more structural possibilities for hybrid passivated back-contact solar cells, broadens their scope of application, and improves economic benefits.

[0043] In addition, under the premise that the charge transfer layer 31 itself has a certain passivation performance, the interface passivation layer 33 should mainly consider the carrier selective transport performance. Therefore, the thickness of the above-mentioned interface passivation layer 33 is thinner than the inorganic interface passivation layer in the conventional TOPCon battery and HJT battery, and plays an auxiliary repair passivation role. If the interface passivation layer 33 is thicker, it will reduce the probability of carriers in the base layer 1 passing through the interface passivation layer 33, so that the probability of carriers being collected by the charge transfer layer 31 is reduced. Taking the TOPCon battery as an example, the thickness of the conventional tunneling oxide layer is 1~2 nm, but the thickness of the interface passivation layer 33 in the present disclosure is less than or equal to 1 nm.

[0044] In one embodiment, the hybrid passivated back contact solar cell may further include: a passivation anti-reflection layer 7 disposed on the light-receiving surface 11 of the substrate layer 1 .

[0045] like Figure 7 and Figure 8 As shown, the light-receiving surface 11 of the silicon substrate in this embodiment is formed with a textured structure to increase frontal light trapping. Furthermore, a passivation anti-reflection layer 7 is formed on the light-receiving surface 11. The passivation anti-reflection layer 7 can be made of materials such as amorphous silicon and silicon nitride, which helps further reduce optical losses on the light-receiving surface 11 and improve the power generation efficiency of the cell.

[0046] refer to Figures 1 to 9 This embodiment also provides a method for preparing a hybrid passivated back contact solar cell, which is used to prepare the above hybrid passivated back contact solar cell. Figure 9 Schematic diagram of the preparation method, the preparation method specifically comprises the following steps: Step S901 : providing a base layer 1 , wherein the base layer 1 includes a light-receiving surface 11 and a backlight surface 12 that are oppositely disposed.

[0047] refer to Figure 1 In this embodiment, the base layer 1 is a silicon base, which is formed by polishing the double sides of a silicon wafer to prepare a silicon base for a solar cell.

[0048] Step S902 , forming a first passivation contact structure 2 on the backlight surface 12 , the first passivation contact structure 2 including a stacked tunneling oxide layer 21 and a doping layer 22 , the tunneling oxide layer 21 being disposed on a portion of the backlight surface 12 , and the doping layer 22 being disposed on the tunneling oxide layer 21 .

[0049] refer to Figure 2 First, an initial tunneling oxide layer 21a and an initial polysilicon layer are deposited on the entire backlight surface 12 in sequence; then, the initial polysilicon layer is subjected to phosphorus diffusion treatment to obtain an initial doped layer 22a and a phosphosilicate glass layer 8 (also known as a PSG layer); then, a laser is used to partially remove the initial doped layer 22a and the initial tunneling oxide layer 21a located in the p-region 122 of the substrate layer and the entire phosphosilicate glass layer 8 to form the tunneling oxide layer 21 and the doped layer 22 of the first passivation contact structure 2, and expose the surface of the p-region 122 on the backlight surface 12 of the silicon substrate. It can be seen that this surface also has a textured surface, as shown in FIG. Figure 3 As shown, for the sake of convenience, this part of the structure is omitted in the figure.

[0050] 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 transfer layer 31 . The charge transfer layer 31 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.

[0051] This step S903 specifically includes the following steps: In step S9031 a , an initial charge transport layer 31 a is formed on the entire surface of the backlight surface 12 of the base layer 1 . The initial charge transport layer 31 a covers the first passivation contact structure 2 and the backlight surface 12 exposed by the first passivation contact structure 2 .

[0052] For example, the initial charge transfer layer 31a can be deposited on the entire backlight side 12 of the base layer 1 by plasma chemical vapor deposition, covering the entire first passivation contact structure 2 and the backlight side 12 surface exposed by the first passivation contact structure 2, such as Figure 4 shown.

[0053] In step S9032 a , a portion of the initial charge transport layer 31 a located on the first passivation contact structure 2 is removed to form an opening exposing the doped layer 22 .

[0054] For example, the initial charge transport layer 31a on the surface of the first passivation contact structure 2 can be patterned and grooved by 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 base layer, as shown in FIG. Figure 5 As shown, the first opening 311 provides a channel for subsequently connecting the first electrode 4 or the first transparent conductive layer 23 with the doping layer 22 .

[0055] Step S904 , forming a first electrode 4 and a second electrode 5 , wherein the first electrode 4 is connected to the doping layer 22 , and the second electrode 5 is connected to the charge transport layer 31 .

[0056] For example, the electrode paste can be printed on the charge transport layer 31 corresponding to the first opening 311 and the p-region 122 by screen printing or the like, and then sintered to form the first electrode 4 connected to the doping layer 22 and the second electrode 5 connected to the charge transport layer 31. Figure 7 shown.

[0057] In the preparation method of the hybrid passivated back contact cell of this embodiment, first, a TOPCon cell-related structure is applied to the n-region 121 of the backlight surface 12 of the substrate layer 1 to form a tunneling oxide layer 21 and a doping layer 22 to achieve efficient transmission of electrons; then, a perovskite cell-related structure is applied to the p-region 122 of the backlight surface to form a hole transport layer to achieve efficient transmission of holes, and different types of passivation contact structures are formed on one side of the backlight surface 12 of the cell, so that the thin films in different polarity regions of the formed hybrid passivated back contact solar cell have good performance, a simple preparation process, and high economic benefits while improving the photoelectric conversion efficiency of the cell.

[0058] In one embodiment, after the step S902 of forming the first passivation contact structure 2 on the backlight surface 12 and before the step S903 of forming the second passivation contact structure 3 on the backlight surface 12, the process further includes: Cleaning and texturing the battery structure having the base layer 1 and the first passivation contact structure 2 to form a texturing structure on the light-receiving surface 11 and the backlight surface 12 not covered by the first passivation contact structure 2; A passivation anti-reflection layer 7 is deposited on the light-receiving surface 11 of the base layer 1 .

[0059] Specifically, the cleaning process removes impurities on the battery surface, and the texturing process forms a velvet structure to increase light trapping. Figure 3 The velvet structure of the light-receiving surface 11 and the passivation anti-reflection layer 7 are superimposed to maximize the utilization of sunlight and improve the power generation efficiency. The velvet structure of the backlight surface 12 helps to improve the structural stability of the charge transfer layer 31 and reduce interface recombination.

[0060] See also 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, further comprising: Depositing an initial transparent conductive layer on the entire backlight surface 12 of the substrate layer 1; The initial transparent conductive layer is partially removed to form a second opening 9 offset from the first opening 311 , thereby obtaining a first transparent conductive layer 23 connected to the doping layer 22 through the first opening 311 and a second transparent conductive layer 32 connected to the charge transport layer 31 .

[0061] The first transparent conductive layer 23 and the second transparent conductive layer 32 are formed respectively by full-surface deposition and then partial removal. The material consistency is high, which helps to ensure the charge extraction performance of the first passivation contact structure 2 and the second passivation contact structure 3, and improve the power generation efficiency and battery life.

[0062] Example 2 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: Step S9031b, forming an initial charge transport layer 31a on the entire surface of the backlight surface 12 of the base layer 1, wherein 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; Step S1032b, remove all the initial charge transfer layer 31a on the surface and surrounding side of the first passivation contact structure 2 to completely expose the first passivation contact structure 2 and form a charge transfer layer 31, and form a relatively isolated isolation space 6 between the charge transfer layer 31 and the first passivation contact structure 2, as shown in FIG. Figure 10 shown.

[0063] On the backlight side, the first passivation contact structure 2 of the n-region 121 and the second passivation contact structure 3 of the p-region 122 are completely separated by the isolation space 6, forming a distinct isolation region between regions of different polarity. This effectively blocks the p-region 122 and the n-region 121 to reduce the risk of short circuit leakage, greatly reducing the recombination of electrons and holes, and also reducing the parasitic absorption of the charge transfer layer 31, thereby improving charge transfer efficiency and further enhancing battery performance. Of course, it is not ruled out that the isolation space 6 can be formed by methods such as photolithography or etching to simplify the manufacturing process.

[0064] See also Figures 11 to 13 In one embodiment, the structure of the interface passivation layer 33, the passivation anti-reflection layer 7, the first transparent conductive layer 23, and the second transparent conductive layer 32 may be the same as those in Example 1. The tunneling oxide layer 21, the doping 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 base layer 1 overlap; the interface passivation layer 33, the charge transfer layer 31, and the second transparent conductive layer 32 of the second passivation contact structure 3 are formed in the same shape. The rest of the content will not be repeated here.

[0065] In summary, the batteries corresponding to Example 1 and Example 2 are obtained. In the batteries of Example 1 and Example 2, the first passivation contact structure 2 located in the n region 121 includes a tunneling oxide layer 21, a doping 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 Example 1 is as follows: Figure 8 As shown, the battery structure of Example 2 is as follows Figure 13 shown.

[0066] In addition, comparative example 1 cells and comparative example 2 cells were selected, wherein the comparative example 1 cells and comparative example 2 cells both adopted the same passivation contact structure in the p-region as the comparative example 1 cells and comparative example 2 cells, but comparative example 1 adopted a tunneling oxide layer, a p-type doped polycrystalline silicon layer, and a transparent conductive layer in the form of a conventional TOPCon cell as the passivation contact structure in the p-region, while comparative example 2 adopted an intrinsic amorphous silicon layer, a p-type doped amorphous silicon layer, and a transparent conductive layer in the form of an HJT cell in the p-region.

[0067] Based on this, the batteries of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were respectively subjected to electrical performance tests, and the data shown in the following table were obtained:

[0068] As can be seen from the table above, the batteries of Example 1 and Example 2 have a high conversion efficiency ( η )、Open circuit voltage( V oc )、Short-circuit current density(J sc ) and the fill factor ( FF ) and other current performance parameters are better than those of Comparative Example 1 and Comparative Example 2, that is, the second passivation contact structure 3 used in the p-region 122 of Example 1 and Example 2 can effectively improve the cell efficiency of the back-contact solar cell.

[0069] Specifically, first, for the battery of Example 1, the hole transport layer of a low-cost perovskite battery is used as the charge transport layer 31 in the p-region 122 to achieve passivation and transport of carriers. The hole transport layer itself has certain passivation properties. At the same time, it is prepared using a low-temperature process, which avoids secondary high-temperature effects on the substrate layer 1 and ensures the performance of the substrate layer 1. In addition, the hole transport layer is combined with a high-quality inorganic interface passivation layer 33, making the carrier passivation and transport performance of the p-region much higher than that of Comparative Examples 1 and 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 the n-region 121 to prevent short-circuit leakage, a clear isolation space 6 is formed between the 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 of the battery than that of Example 1. However, the overall electrical performance is not much different from that of Example 1, but is still significantly higher than that of Comparative Examples 1 and 2. In Comparative Example 1, the poor passivation and contact performance of the p-poly layer severely degraded the battery performance, resulting in the lowest battery efficiency. In Comparative Example 2, although the p-region utilizes a boron-doped amorphous silicon passivation contact, further improving performance over p-poly and achieving higher electrical performance than Comparative Example 1, the overall equipment investment cost is high, and the passivation performance of the boron-doped amorphous silicon layer remains relatively low compared to the batteries of Examples 1 and 2, resulting in lower electrical performance than in Examples 1 and 2.

[0070] The further functional description of each of the above structures is the same as that of the above corresponding embodiments and will not be repeated here.

[0071] While the above description does not provide detailed technical details regarding patterning and etching of each layer, those skilled in the art will appreciate that various technical means can be employed to form layers, regions, and the like in desired shapes. Furthermore, those skilled in the art may devise methods that differ from those described above to form the same structure. Furthermore, while each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously combined.

[0072] Although the embodiments of the present disclosure have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A hybrid passivated back contact solar cell, characterized in that: include: a base layer, the base layer comprising a light-receiving surface and a backlight surface that are oppositely disposed; A first passivation contact structure includes a tunneling oxide layer and a doping layer stacked together, wherein the tunneling oxide layer is disposed on a portion of the backlight surface, and the doping layer is disposed on the tunneling oxide layer; a second passivation contact structure comprising a charge transport layer, wherein the charge transport layer at least covers the backlight surface exposed by the first passivation contact structure; the first passivation contact structure and the second passivation contact structure have opposite conductivity types; A first electrode and a second electrode, the first electrode is connected to the doping 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 passivation contact structure further includes a first transparent conductive layer disposed on the doping layer, and the first electrode is 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 the second electrode is disposed on the second transparent conductive layer; the first transparent conductive layer and the second transparent conductive layer are spaced apart.

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

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

6. The hybrid passivated back contact solar cell according to claim 1, characterized in that: The second passivation contact structure further includes: an interface passivation layer disposed between the charge transport layer and the base 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 a silicon oxide layer, an aluminum oxide layer, and an intrinsic amorphous silicon layer.

8. The hybrid passivated back contact solar cell according to claim 1, characterized in that: Also includes: The passivation anti-reflection layer is arranged on the light-receiving surface of the base layer.

9. A method for preparing a hybrid passivated back contact solar cell, for preparing the hybrid passivated back contact solar cell according to any one of claims 1 to 8, characterized in that: include: Providing a base layer, the base layer comprising a light-receiving surface and a backlight surface disposed opposite to each other; forming a first passivation contact structure on the backlight surface, wherein the first passivation contact structure includes a tunneling oxide layer and a doping layer stacked together, wherein the tunneling oxide layer is disposed on a portion of the backlight surface, and the doping layer is disposed on the tunneling oxide layer; forming a second passivation contact structure on the backlight surface, the second passivation contact structure comprising a charge transfer layer, the charge transfer layer at least covering the backlight surface exposed by the first passivation contact structure; the first passivation contact structure and the second passivation contact structure have opposite conductivity types; A first electrode and a second electrode are formed, wherein the first electrode is connected to the doping layer, and the second electrode is connected to the charge transport layer.

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

11. The method for preparing a hybrid passivated back contact solar cell according to claim 9, wherein: The forming of the second passivation contact structure on the backlight surface comprises: forming an initial charge transport layer on the entire backlight side of the base layer, wherein the initial charge transport layer covers the first passivation contact structure and the backlight side exposed by the first passivation contact structure; The entire initial charge transfer layer located on the surface and surrounding side of the first passivation contact structure is removed to completely expose the first passivation contact structure and form the charge transfer layer, with a relatively isolated isolation space being formed between the charge transfer layer and the first passivation contact structure.

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