A back contact cell and a method of manufacturing the same, a back contact stacked cell, and a photovoltaic module

Abstract

The application relates to the photovoltaic technology field, in particular to a back contact cell, a preparation method thereof, a back contact laminated cell and a photovoltaic module. The back contact cell comprises a substrate and a first passivation structure, and a first surface of the substrate is sequentially provided with a first hydrogenated amorphous silicon oxide layer, a second hydrogenated amorphous silicon oxide layer and a P-type doped layer. The oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer is X1, the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer is X2, and X1 and X2 satisfy X1>X2. By arranging the laminated structure with the oxygen doping ratio gradient design, the asymmetric carrier transport channel can be formed, the blocking effect on the electrons and the transmission effect on the holes can be improved, the selective transmission of the carriers can be realized, the parasitic absorption at the interface can be reduced, the probability of the repeated absorption of the light by the substrate can be increased, the open-circuit voltage and the short-circuit current of the back contact cell can be improved, and the photoelectric conversion efficiency of the back contact cell can be improved.

Description

Technical Field

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

[0002] Currently, in the fabrication of back-contact solar cells, an intrinsic amorphous silicon layer and a doped amorphous silicon layer are sequentially deposited on the back surface of the substrate to form a contact passivation structure. This reduces electron-hole recombination and improves the performance of the back-contact solar cell. However, due to the poor structural and thermal stability of intrinsic amorphous silicon (e.g., intrinsic hydrogenated amorphous silicon layer, ia-Si:H), it is easily damaged during subsequent doping and annealing processes, which can affect the overall passivation effect and consequently reduce the performance of the back-contact solar cell. Summary of the Invention

[0003] In view of this, this application provides a back contact cell and its preparation method, a back contact tandem cell and a photovoltaic module, to solve the technical problem that the back contact cell is easily damaged during the preparation process in the prior art, which easily affects the overall passivation effect.

[0004] This application provides a back contact battery, which includes a substrate and a first passivation structure. The substrate has a first surface and a second surface disposed opposite to each other along a first direction. The first passivation structure is disposed on the first surface and includes a first passivation layer and a P-type doped layer stacked along the first direction. The P-type doped layer is connected to the side of the first passivation layer away from the substrate.

[0005] The first passivation layer further includes a first hydrogenated amorphous silicon oxide layer and a second hydrogenated amorphous silicon oxide layer stacked along a first direction. The second hydrogenated amorphous silicon oxide layer is located between the first hydrogenated amorphous silicon oxide layer and the P-type doped layer. The oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer is X1, and the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer is X2, and X1 and X2 satisfy X1 > X2.

[0006] The beneficial effects of this embodiment are as follows: by setting a first passivation layer and a P-type doped layer with oxygen elements on the first surface of the substrate, the passivation effect at the interface can be effectively improved and the parasitic absorption at the interface can be reduced, thereby improving the open-circuit voltage and short-circuit current of the back contact cell. Furthermore, by setting the first passivation layer as a stacked structure with an oxygen doping ratio gradient design, not only can an asymmetric carrier transport channel be formed to further improve the blocking effect on electrons and the transport effect on holes, thereby better realizing the selective transport of carriers, but also a gradient structure with a reduced refractive index can be formed to further increase the probability of light being repeatedly absorbed by the substrate, thereby improving the photoelectric conversion efficiency of the back contact cell.

[0007] In one possible implementation, the first passivation layer further includes a third hydrogenated amorphous silicon oxide layer. Along the first direction, the third hydrogenated amorphous silicon oxide layer is located between the first hydrogenated amorphous silicon oxide layer and the second hydrogenated amorphous silicon oxide layer. The oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer is X3, and X1, X2 and X3 satisfy X3 > X1 and X3 > X2.

[0008] In one possible implementation, the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer satisfies 9%≤X1≤12%, the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer satisfies 6%≤X2≤8%, and the oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer satisfies 30%≤X3≤35%.

[0009] In one possible implementation, the refractive index of the first passivation layer is R1, and R1 satisfies 3.2≤R1≤3.6, and the extinction coefficient of the first passivation layer is K1, and K1 satisfies 0.5%≤K1≤1%.

[0010] In one possible implementation, the back contact battery further includes a second passivation structure disposed on the second surface. The second passivation structure includes a second passivation layer and an antireflection layer stacked along a first direction, with the antireflection layer connected to the side of the second passivation layer facing away from the substrate.

[0011] The second passivation layer further includes a first intrinsic hydrogenated amorphous silicon oxide layer and a second intrinsic hydrogenated amorphous silicon oxide layer stacked along the first direction. The second intrinsic hydrogenated amorphous silicon oxide layer is located between the first intrinsic hydrogenated amorphous silicon oxide layer and the antireflection layer. The oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer is X4, and the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer is X5, and X4 and X5 satisfy X4 < X5.

[0012] In one possible implementation, the oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer satisfies 0.5% ≤ X4 ≤ 2%, and the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer satisfies 3% ≤ X5 ≤ 35%.

[0013] In one possible implementation, the antireflection layer further includes at least one layer of silicon nitride, the refractive index of which is R2, and R2 satisfies 1.9≤R2≤2.1.

[0014] In one possible implementation, the first surface includes a first region and a second region alternately arranged along a second direction, a first passivation structure is disposed in the first region, and the back contact battery further includes a third passivation structure disposed in the second region.

[0015] The third passivation structure includes a tunneling oxide layer and an N-type doped layer stacked along the first direction, with the N-type doped layer connected to the side of the tunneling oxide layer away from the substrate.

[0016] In one possible implementation, the back contact battery further includes a transparent conductive layer, which is connected along a first direction to the side of the P-type doped layer away from the first passivation layer and the N-type doped layer away from the tunneling oxide layer.

[0017] The back contact battery also includes a first electrode and a second electrode. Along the first direction, the first electrode is connected to the side of the transparent conductive layer away from the P-type doped layer, and the second electrode is connected to the side of the transparent conductive layer away from the N-type doped layer. Along the second direction, the first electrode and the second electrode are arranged alternately and spaced apart.

[0018] This application also provides a preparation method, the preparation method comprising:

[0019] A substrate is provided, the substrate having a first surface and a second surface disposed opposite to each other along a first direction.

[0020] A first hydrogenated amorphous silicon oxide layer is deposited on the first surface using a first process gas.

[0021] A second hydrogenated amorphous silicon oxide layer is deposited on the first hydrogenated amorphous silicon oxide layer using a second process gas.

[0022] A P-type doped layer is deposited on the second hydrogenated amorphous silicon oxide layer using a third process gas.

[0023] During the deposition process, the hydrogen dilution ratio of the first process gas is RH, and RH satisfies 8≤RH≤12, the first pressure is P1, and P1 satisfies 50pa≤P1≤180pa, and the first temperature is T1, and T1 satisfies 180℃≤T1≤230℃, so that the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer and the second hydrogenated amorphous silicon oxide layer satisfies X1>X2.

[0024] The beneficial effects of this embodiment are as follows: During the deposition process, a first hydrogenated amorphous silicon oxide layer can be covered on the first surface, a second hydrogenated amorphous silicon oxide layer can be covered on the first hydrogenated amorphous silicon oxide layer, and a P-type doped layer can be covered on the second hydrogenated amorphous silicon oxide layer, thereby forming a first passivation structure composed of a first passivation layer and a P-type doped layer. This design effectively improves the passivation effect at the interface and reduces parasitic absorption at the interface, thereby increasing the open-circuit voltage and short-circuit current of the back contact cell. Furthermore, by setting the first and second hydrogenated amorphous silicon oxide layers as a stacked structure with a gradient oxygen doping ratio, it not only further improves the blocking effect on electrons and the transport effect on holes to better achieve selective carrier transport, but also allows long-wavelength light that is not absorbed by the substrate to pass through without loss, thus optimizing optical performance, reducing parasitic absorption, and improving the effective absorption rate of long-wavelength light by the back contact cell, thereby improving the photoelectric conversion efficiency of the back contact cell.

[0025] In one possible implementation, after the step of depositing a first hydrogenated amorphous silicon oxide layer on the first surface using a first process gas, the preparation method further includes:

[0026] A third hydrogenated amorphous silicon oxide layer is deposited on the first hydrogenated amorphous silicon oxide layer using a second process gas.

[0027] A second hydrogenated amorphous silicon oxide layer is deposited on the third hydrogenated amorphous silicon oxide layer using a second process gas.

[0028] Among them, the oxygen doping ratios of the third hydrogenated amorphous silicon oxide layer, the first hydrogenated amorphous silicon oxide layer, and the second hydrogenated amorphous silicon oxide layer satisfy X3 > X1 and X3 > X2.

[0029] In one possible implementation, the preparation method further includes, during the deposition of a first hydrogenated amorphous silicon oxide layer on the first surface using a first process gas:

[0030] A first intrinsic hydrogenated amorphous silicon oxide layer is deposited on the second surface using a first process gas.

[0031] A second intrinsic hydrogenated amorphous silicon oxide layer is deposited on the first intrinsic hydrogenated amorphous silicon oxide layer using a second process gas.

[0032] The oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer and the second intrinsic hydrogenated amorphous silicon oxide layer satisfies X4 < X5.

[0033] In one possible implementation, after the step of depositing a second intrinsic hydrogenated amorphous silicon oxide layer on the first intrinsic hydrogenated amorphous silicon oxide layer using a second process gas, the preparation method further includes:

[0034] An antireflection layer is deposited on the second intrinsic hydrogenated amorphous silicon oxide layer using a fourth process gas.

[0035] During the deposition process, the silicon-nitrogen atomic ratio in the fourth process gas is Si / N, and Si / N satisfies 0.5≤Si / N≤2.5. The hydrogen concentration in the fourth process gas is CH, and CH satisfies 15%≤CH≤50%. The second pressure is P2, and P2 satisfies 50pa≤P2≤200pa. The second temperature is T2, and T2 satisfies 170℃≤T2≤250℃.

[0036] This application also provides a back-contact stacked battery, which includes a back-contact bottom battery and a perovskite top battery. The perovskite top battery is electrically connected to the front side of the back-contact bottom battery, and the back-contact bottom battery is any of the back-contact batteries described above.

[0037] The beneficial effects of this embodiment are as follows: When the perovskite top cell and the back contact bottom cell are electrically connected on the front side to form a back contact tandem cell, the overall photoelectric conversion efficiency can be improved by utilizing the solar spectrum in different wavelength bands. Specifically, the perovskite top cell can use a wide bandgap to absorb high-energy short-wavelength photons to reduce light loss and increase open-circuit voltage, while the back contact bottom cell can use a narrow bandgap to absorb low-energy long-wavelength photons to reduce photothermal loss and increase current density. Thus, the photoelectric conversion efficiency of the back contact tandem cell can be improved through the synergistic effect of the perovskite top cell and the back contact bottom cell. Simultaneously, the back contact tandem cell also includes an interconnect layer located between the perovskite top cell and the back contact bottom cell along the thickness direction of the back contact tandem cell. This interconnect layer serves to connect and transmit current, facilitating current matching between the two cells and reducing series resistance, thereby increasing the fill factor and optimizing charge transfer efficiency.

[0038] This application also provides a photovoltaic module, which includes a cover plate, an encapsulation layer and at least one battery string. The cover plate is connected to the battery string through the encapsulation layer, and the battery string includes a plurality of back-contact batteries as described in any of the above claims or back-contact stacked batteries as described in the above claims.

[0039] The beneficial effects of this embodiment are as follows: The photovoltaic module may include multiple battery strings, which are electrically connected in series and / or parallel. The solar cells of each battery string can be the aforementioned back-contact cells or back-contact tandem cells. By using a hydrogenated amorphous silicon oxide tandem structure as the first passivation layer and P-type doped layer, and an intrinsic hydrogenated amorphous silicon oxide tandem structure as the second passivation layer and antireflection layer, the passivation effect of the first and second surfaces can be effectively improved, and parasitic absorption at the interface can be reduced. This can improve the open-circuit voltage and short-circuit current of the back-contact cells or back-contact tandem cells. Furthermore, the tandem structure designed with oxygen doping ratio gradient can not only further improve the blocking effect on electrons and the transport effect on holes to better achieve selective transport of charge carriers, but also further widen the bandgap to improve the utilization rate of long-wavelength light, thereby improving the photoelectric conversion efficiency of the back-contact cells or back-contact tandem cells.

[0040] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of the solar cell provided in one embodiment of this application;

[0043] Figure 2 yes Figure 1 A schematic diagram of the structure of the first passivation layer and the second passivation layer.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1-Base;

[0046] 11-First surface;

[0047] 111 - First Area;

[0048] 112 - Second Zone;

[0049] 12-Second surface;

[0050] 2-First passivation structure;

[0051] 21 - First passivation layer;

[0052] 211 - First hydrogenated amorphous silicon oxide layer;

[0053] 212 - Second hydrogenated amorphous silicon oxide layer;

[0054] 213-Third hydrogenated amorphous silicon oxide layer;

[0055] 22-P type doped layer;

[0056] 3-Second passivation structure;

[0057] 31 - Second passivation layer;

[0058] 311 - First intrinsic hydrogenated amorphous silicon oxide layer;

[0059] 312 - Second intrinsic hydrogenated amorphous silicon oxide layer;

[0060] 32-Antireflective layer;

[0061] 321-Hydrogenated silicon nitride layer;

[0062] 4-Third passivation structure;

[0063] 41-Tunneling oxide layer;

[0064] 42-N type doped layer;

[0065] 5-Transparent conductive layer;

[0066] 51 - First conductive segment;

[0067] 52 - Second conductive segment;

[0068] 6-First electrode;

[0069] 7-Second electrode.

[0070] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0071] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0072] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0073] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0074] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0075] Embodiments of this application provide a back contact battery, such as Figure 1 As shown, the back contact battery includes a substrate 1 and a first passivation structure 2. The substrate 1 has a first surface 11 and a second surface 12 disposed opposite to each other along a first direction x. The first passivation structure 2 is disposed on the first surface 11, and the first passivation structure 2 further includes a first passivation layer 21 and a P-type doped layer 22 stacked along the first direction x. The P-type doped layer 22 is connected to the side of the first passivation layer 21 away from the substrate 1.

[0076] The first passivation layer 21 further includes a first hydrogenated amorphous silicon oxide layer 211 and a second hydrogenated amorphous silicon oxide layer 212 stacked along the first direction x. The second hydrogenated amorphous silicon oxide layer 212 is located between the first hydrogenated amorphous silicon oxide layer 211 and the P-type doped layer 22. The oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer 211 is X1, and the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer 212 is X2, and X1 and X2 satisfy X1 > X2.

[0077] It should be noted that the substrate 1 can be doped with N-type elements, such as one or a combination of pentavalent elements like phosphorus, arsenic, or antimony. The substrate 1 can also be doped with P-type elements, such as one or a combination of trivalent elements like boron, indium, or gallium. In the embodiments of this application, a substrate 1 doped with N-type elements will be used for description. Meanwhile, the thickness direction of the back contact battery is defined as the first direction x, and the width direction of the back contact battery is defined as the second direction y. That is, the first direction x and the second direction y intersect and are perpendicular. The first surface 11 is used as the backlight surface of the back contact battery, and the second surface 12 is used as the light-receiving surface of the back contact battery. That is, the first surface 11 is not directly exposed to sunlight, while the second surface 12 can be directly exposed to sunlight.

[0078] In this embodiment, a first passivation layer 21 and a P-type doped layer 22 are sequentially deposited on the first surface 11 of the substrate 1. The first passivation layer 21 can saturate the dangling bonds on the surface of the substrate 1 to form chemical passivation, thereby reducing the recombination rate of electrons and holes at the first surface 11. The P-type doped layer 22 can form a heterojunction with the substrate 1 to establish a built-in electric field, thereby achieving selective transport of charge carriers. Furthermore, under the combined action of the first passivation layer 21 and the P-type doped layer 22, the recombination of electrons and holes can be further suppressed, which is beneficial to further improve the passivation effect of chemical passivation, thereby improving the open-circuit voltage and fill factor of the back contact battery and optimizing the electrical performance of the back contact battery.

[0079] Optionally, the first passivation layer 21 is hydrogenated amorphous silicon oxide (a-SiOx:H), and the P-type doped layer 22 is P-type hydrogenated amorphous silicon (pa-Si:H).

[0080] In contrast to the existing first passivation layer 21 which uses hydrogenated amorphous silicon (a-Si:H), the first passivation layer 21 in this embodiment introduces oxygen elements so that the strong electronegativity of oxygen atoms can better saturate the dangling bonds on the surface of the substrate 1 to form more stable and stronger chemical bonds (Si-O), thereby improving the passivation effect of chemical passivation, reducing the interface defect density, and thus helping to improve the open circuit voltage of the back contact battery.

[0081] Meanwhile, hydrogenated amorphous silicon oxide has a wider bandgap than hydrogenated amorphous silicon. The wider bandgap allows the first passivation layer 21 to have a higher valence band offset, making the holes more concentrated. This facilitates the collection of holes by P-type hydrogenated amorphous silicon, thereby improving the hole collection efficiency and transmission efficiency.

[0082] In addition, the wide bandgap can reduce the refractive index and extinction coefficient of the first passivation layer 21, making it more transparent so that long-wavelength light can pass through without damage, which facilitates absorption by the substrate 1, reduces parasitic absorption, and thus helps to increase the short-circuit current of the back contact battery.

[0083] Optionally, the first passivation layer 21 further includes a first hydrogenated amorphous silicon oxide layer 211 (a-SiOx:H-1) and a second hydrogenated amorphous silicon oxide layer 212 (a-SiOx:H-2) stacked along the first direction x, that is, the first hydrogenated amorphous silicon oxide layer 211 is in contact with the substrate 1, and the second hydrogenated amorphous silicon oxide layer 212 is in contact with the P-type doped layer 22.

[0084] The oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212 satisfies X1 > X2, enabling a gradient structure with a lower potential barrier between them. This allows for the formation of an asymmetric carrier transport channel between the substrate 1 and the P-type doped layer 22. Specifically, the first hydrogenated amorphous silicon oxide layer 211 forms a higher potential barrier, providing a more effective and efficient barrier to electron transport. The second hydrogenated amorphous silicon oxide layer 212 forms a lower potential barrier, allowing holes to move rapidly after crossing the high barrier through the combined action of the gradient structure and the P-type doped layer 22. This not only reduces recombination efficiency at the interface to improve the open-circuit voltage of the back contact battery but also increases hole lifetime for better collection and transport, thereby optimizing the electrical performance of the back contact battery.

[0085] Simultaneously, it can also create a gradient structure with decreasing refractive index between the two layers, allowing the refractive index between adjacent layers to gradually decrease. This improves the refractive index matching effect between the substrate 1 and the first hydrogenated amorphous silicon oxide layer 211, the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212, and the second hydrogenated amorphous silicon oxide layer 212 and the P-type doped layer 22. This avoids high extinction coefficients caused by excessive refractive index differences, thereby increasing the probability of light being repeatedly absorbed by the substrate 1, and further improving the working performance of the back contact battery.

[0086] In addition, the first hydrogenated amorphous silicon oxide layer 211 enables long-wavelength light that is not absorbed by the substrate 1 to pass through without loss, thereby optimizing the optical performance at the interface with the substrate 1, reducing parasitic absorption, and improving the effective absorption rate of long-wavelength light, thereby increasing the short-circuit current of the back contact battery.

[0087] Therefore, by setting a first passivation layer 21 and a P-type doped layer 22 with oxygen elements on the first surface 11 of the substrate 1, this embodiment can effectively improve the passivation effect at the interface and reduce parasitic absorption at the interface, thereby improving the open-circuit voltage and short-circuit current of the back contact cell. Furthermore, by setting the first passivation layer 21 as a stacked structure with an oxygen doping ratio gradient design, it can not only form an asymmetric carrier transport channel to further improve the blocking effect on electrons and the transport effect on holes, thereby better realizing the selective transport of carriers, but also form a gradient structure with a reduced refractive index to further increase the probability of light being repeatedly absorbed by the substrate 1, thereby improving the photoelectric conversion efficiency of the back contact cell.

[0088] In one specific implementation, such as Figure 2 As shown, the first passivation layer 21 also includes a third hydrogenated amorphous silicon oxide layer 213 (a-SiOx:H-3). Along the first direction x, the third hydrogenated amorphous silicon oxide layer 213 is located between the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212. The oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer 213 is X3, and X1, X2 and X3 satisfy X3 > X1 and X3 > X2.

[0089] In this embodiment, along the direction of the substrate 1 toward the P-type doped layer 22, a third hydrogenated amorphous silicon oxide layer 213 with a higher oxygen doping ratio is provided between the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212. This results in the oxygen doping ratio changing trend first increasing and then decreasing, and the refractive index changing trend first decreasing and then increasing. As a result, the third hydrogenated amorphous silicon oxide layer 213 can reflect the light reaching the back of the battery back to the substrate 1 as much as possible, so that the substrate 1 can repeatedly absorb it. This is beneficial to further reduce parasitic absorption, improve the utilization rate of long-wavelength light, and thus improve the long-wavelength response and short-circuit current of the back contact battery.

[0090] Meanwhile, the three-layer hydrogenated amorphous silicon oxide can form a double barrier structure, so that the barrier changes by first rising and then falling. This can not only accurately realize the effective transport of holes, but also further improve the blocking effect on electrons. Even if a small number of electrons manage to cross the first hydrogenated amorphous silicon oxide layer 211, they will be reflected back by the third hydrogenated amorphous silicon oxide layer 213, which helps to further reduce the recombination efficiency of electrons and holes at the interface.

[0091] In addition, the band difference between the three hydrogenated amorphous silicon oxide layers can generate a built-in electric field at the interface, which can help holes move toward the P-type doped layer 22, thereby further improving the hole collection efficiency and transport efficiency.

[0092] In one possible implementation, the thickness of the first passivation layer 21 is H1, and H1 satisfies 2nm≤H1≤10nm, specifically it can be 2nm, 2.2nm, 2.4nm, 2.6nm, 2.8nm, 3nm, 3.2nm, 3.4nm, 3.6nm, 3.8nm, 4nm, 4.2nm, 4.4nm, 4.6nm, 4.8nm, 5nm, 5.2nm, 5.4nm, 5.6nm, 5.8nm, 6nm, 6.2nm, 6.4nm, 6.6nm, 6.8nm, 7nm, 7.2nm, 7.4nm, 7.6nm, 7.8nm, 8nm, 8.2nm, 8.4nm, 8.6nm, 8.8nm, 9nm, 9.2nm, 9.4nm, 9.6nm, 9.8nm, 10nm, etc.

[0093] Optionally, the thicknesses of the first hydrogenated amorphous silicon oxide layer 211, the second hydrogenated amorphous silicon oxide layer 212, and the third hydrogenated amorphous silicon oxide layer 213 may be equal or unequal.

[0094] In one specific embodiment, the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer 211 satisfies 9%≤X1≤12%, and X1 can specifically be 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10%, 10.1%, 10.2%, 10.3%, 10.4%, 10.5%, 10.6%, 10.7%, 10.8%, 10.9%, 11%, 11.1%, 11.2%, 11.3%, 11.4%, 11.5%, 11.6%, 11.7%, 11.8%, 11.9%, 12%, etc.

[0095] When the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer 211 satisfies 9% ≤ X1 ≤ 12%, the first hydrogenated amorphous silicon oxide layer 211 can more stably and firmly saturate the dangling bonds of the substrate 1, thereby improving the passivation effect, reducing the interface defect density, and thus improving the hole lifetime and the open-circuit voltage of the back contact cell. Simultaneously, the first hydrogenated amorphous silicon oxide layer 211, with its higher oxygen doping ratio, not only possesses a lower refractive index and extinction coefficient to reduce parasitic absorption at the interface, but also a higher potential barrier to satisfy the selective transport of charge carriers, thus playing a transitional role and avoiding the risk of holes being hindered during transport due to an excessively high barrier, thereby contributing to improved photoelectric conversion efficiency of the back contact cell.

[0096] In one specific embodiment, the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer 212 satisfies 6%≤X2≤8%, and X2 can specifically be 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8%, etc.

[0097] When the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer 212 satisfies 6%≤X2≤8%, the band structure of the second hydrogenated amorphous silicon oxide layer 212 is more matched with that of the P-type doped layer 22, which is beneficial to improving the hole transport efficiency. Furthermore, the second hydrogenated amorphous silicon oxide layer 212 and the P-type doped layer 22 can achieve a good connection effect, which is beneficial to improving the stability and reliability of the film layer. This can improve the mechanical properties of the back contact battery and increase the production yield of the back contact battery.

[0098] In one specific embodiment, the oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer 213 satisfies 30% ≤ X3 ≤ 35%, and X3 can specifically be 30%, 30.1%, 30.2%, 30.3%, 30.4%, 30.5%, 30.6%, 30.7%, 30.8%, 30.9%, 31%, 31.1%, 31.2%, 31.3%, 31.4%, 31.5%, 31.6%, 31.7%, 31.8%, 31.9%, 32%, 32%. 1%, 32.2%, 32.3%, 32.4%, 32.5%, 32.6%, 32.7%, 32.8%, 32.9%, 33%, 33.1%, 33.2%, 33.3%, 33.4%, 33.5%, 33.6%, 33.7%, 33.8%, 33.9%, 34%, 34.1%, 34.2%, 34.3%, 34.4%, 34.5%, 34.6%, 34.7%, 34.8%, 34.9%, 35%, etc.

[0099] When the oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer 213 meets the requirement of 30% ≤ X3 ≤ 35%, the third hydrogenated amorphous silicon oxide layer 213 can ensure the lossless transmission of long-wavelength light, thereby reducing optical loss. This facilitates the subsequent reflection of long-wavelength light back to the substrate 1 for full absorption, which in turn helps to improve the long-wavelength response and short-circuit current of the back contact battery. At the same time, since the third hydrogenated amorphous silicon oxide layer 213 is located between the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212, its potential barrier is the highest compared to the two. Therefore, it can cooperate with the first hydrogenated amorphous silicon oxide layer 211 to block the transmission of electrons from the substrate 1 to the P-type doped layer 22, so as to reduce the recombination efficiency of electrons and holes, which in turn helps to improve the open-circuit voltage of the back contact battery.

[0100] In one specific embodiment, the refractive index of the first passivation layer 21 is R1, and R1 satisfies 3.2≤R1≤3.6, and the extinction coefficient of the first passivation layer 21 is K1, and K1 satisfies 0.5%≤K1≤1%.

[0101] In this embodiment, when the refractive index and extinction coefficient of the first passivation layer 21 meet the above conditions, the refractive index of the first passivation layer 21 is close to that of the substrate 1, and the overall transparency of the first passivation layer 21 is high, so that when light is transmitted to the first passivation layer 21, the loss of long-wavelength light is small, so that it can be reflected back to the substrate 1 almost undamaged and absorbed, thereby helping to reduce parasitic absorption and improve the long-wavelength response and short-circuit current of the back contact battery.

[0102] Optionally, R1 can specifically be 3.2, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29, 3.3, 3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, 3.39, 3.4, 3.41, 3.42, 3.43, 3.44, 3.45, 3.46, 3.47, 3.48, 3.49, 3.5, 3.51, 3.52, 3.53, 3.54, 3.55, 3.56, 3.57, 3.58, 3.59, 3.6, etc.

[0103] Optionally, K1 can specifically be 0.5%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%, 0.72%, 0.73%, 0.7 4%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.9%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, 1%, etc.

[0104] In one specific implementation, such as Figure 1 and Figure 2 As shown, the back contact battery also includes a second passivation structure 3, which is disposed on the second surface 12. The second passivation structure 3 includes a second passivation layer 31 and an anti-reflection layer 32 stacked along the first direction x. The anti-reflection layer 32 is connected to the side of the second passivation layer 31 away from the substrate 1.

[0105] The second passivation layer 31 further includes a first intrinsic hydrogenated amorphous silicon oxide layer 311 and a second intrinsic hydrogenated amorphous silicon oxide layer 312 stacked along the first direction x. The second intrinsic hydrogenated amorphous silicon oxide layer 312 is located between the first intrinsic hydrogenated amorphous silicon oxide layer 311 and the antireflection layer 32. The oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer 311 is X4, and the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer 312 is X5, and X4 and X5 satisfy X4 < X5.

[0106] In this embodiment, a second passivation layer 31 and an antireflection layer 32 are sequentially deposited on the second surface 12 of the substrate 1. The second passivation layer 31 can saturate the dangling bonds on the surface of the substrate 1 to form chemical passivation, thereby reducing the recombination rate of electrons and holes at the second surface 12, which is beneficial to improving the open-circuit voltage and fill factor of the back contact battery. The antireflection layer 32 can cancel the reflected light from its upper and lower surfaces to achieve destructive interference, thereby reducing the reflectivity of incident light on the front side of the battery, which is beneficial to improving the short-circuit current of the back contact battery.

[0107] Optionally, the second passivation layer 31 is made of intrinsic hydrogenated amorphous silicon oxide (ia-SiOx:H).

[0108] Compared to existing second passivation layers 31 that use intrinsic hydrogenated amorphous silicon (ia-Si:H), this embodiment introduces oxygen into the second passivation layer 31. The strong electronegativity of oxygen atoms allows for better saturation of the dangling bonds on the substrate 1 surface, forming more stable and robust chemical bonds (Si-O). This improves the passivation effect of chemical passivation, reduces interface defect density, and ultimately enhances the open-circuit voltage of the back contact battery. Furthermore, the lower processing temperature during the fabrication of the second passivation layer 31 avoids thermal damage to the substrate 1, thus ensuring the passivation quality of the second passivation layer 31 and the photoelectric conversion efficiency of the back contact battery.

[0109] Meanwhile, the thermal stability of the second passivation layer 31 is effectively improved, reducing the possibility of performance degradation of the second passivation layer 31 in subsequent processes, which is beneficial to improving the production yield of back contact batteries.

[0110] In addition, the band gap of the second passivation layer 31 becomes wider, so that more short-wavelength light can pass through the second passivation layer 31 and be absorbed by the substrate 1, and more long-wavelength light can pass through the second passivation layer 31 without damage, thereby reducing parasitic absorption, improving long-wavelength response, thereby improving the light absorption efficiency of the back contact battery, which in turn helps to improve the short-circuit current of the back contact battery.

[0111] Optionally, the second passivation layer 31 further includes a first intrinsic hydrogenated amorphous silicon oxide layer 311 (ia-SiOx:H-1) and a second intrinsic hydrogenated amorphous silicon oxide layer 312 (ia-SiOx:H-2) stacked along the first direction x, that is, the first intrinsic hydrogenated amorphous silicon oxide layer 311 is in contact with the substrate 1, and the second intrinsic hydrogenated amorphous silicon oxide layer 312 is in contact with the antireflection layer 32.

[0112] The oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer 311 and the second intrinsic hydrogenated amorphous silicon oxide layer 312 satisfies X4 < X5, which enables a gradient structure with increased refractive index between the two layers. That is, the refractive index of the first intrinsic hydrogenated amorphous silicon oxide layer 311 is lower than that of the second intrinsic hydrogenated amorphous silicon oxide layer 312, thereby reducing the possibility of light reflection inside the battery and improving the light absorption efficiency of the substrate 1.

[0113] Meanwhile, the second intrinsic hydrogenated amorphous silicon oxide layer 312 with a relatively high oxygen doping has high transparency, so that light passing through the antireflection layer 32 can pass through the second intrinsic hydrogenated amorphous silicon oxide layer 312 almost without damage, thereby reducing parasitic absorption and reducing optical loss.

[0114] In addition, the primary intrinsic hydrogenated amorphous silicon oxide layer 311 with relatively low oxygen doping has a lower defect density interface, which allows it to cooperate with the surface of the substrate 1 to form a more stable and reliable passivation effect, which is beneficial to improving the open circuit voltage of the back contact cell.

[0115] Therefore, by providing a second passivation layer 31 and an antireflection layer 32 with oxygen elements on the second surface 12 of the substrate 1, this embodiment can effectively improve the passivation effect at the interface and reduce parasitic absorption at the interface, thereby improving the open-circuit voltage and short-circuit current of the back contact battery. Furthermore, by setting the second passivation layer 31 as a stacked structure with an oxygen doping ratio gradient design, the loss of light during propagation can be further reduced, which is beneficial to improving the photoelectric conversion efficiency of the back contact battery.

[0116] In one possible implementation, the thickness of the second passivation layer 31 is H2, and H2 satisfies 2nm≤H2≤10nm, specifically it can be 2nm, 2.1nm, 2.3nm, 2.5nm, 2.7nm, 2.9nm, 3.1nm, 3.3nm, 3.5nm, 3.7nm, 3.9nm, 4.1nm, 4.3nm, 4.5nm, 4.7nm, 4.9nm, 5.1nm, 5.3nm, 5.5nm, 5.7nm, 5.9nm, 6.1nm, 6.3nm, 6.5nm, 6.7nm, 6.9nm, 7.1nm, 7.3nm, 7.5nm, 7.7nm, 7.9nm, 8.1nm, 8.3nm, 8.5nm, 8.7nm, 5.9nm, 9.1nm, 9.3nm, 9.5nm, 9.7nm, 9.9nm, 10nm, etc.

[0117] Optionally, the thicknesses of the first intrinsic hydrogenated amorphous silicon oxide layer 311, the second intrinsic hydrogenated amorphous silicon oxide layer 312, and the third hydrogenated amorphous silicon oxide layer 213 may be equal or unequal.

[0118] In one specific embodiment, the oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer 311 satisfies 0.5%≤X4≤2%, and X4 can specifically be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, 1.05%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, 1.5%, 1.55%, 1.6%, 1.65%, 1.7%, 1.75%, 1.8%, 1.85%, 1.9%, 1.95%, 2%, etc.

[0119] When the oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer 311 satisfies 0.5% ≤ X4 ≤ 2%, the first intrinsic hydrogenated amorphous silicon oxide layer 311 can balance passivation effect and optical performance. This allows it to reduce the recombination efficiency of electrons and holes at the second surface 12 through a lower interface defect density, thereby achieving good chemical passivation and improving the open-circuit voltage of the back contact cell. Furthermore, because the intrinsic hydrogenated amorphous silicon oxide has a high density and stable fixed positive charge, it can form a field passivation effect to prevent holes from getting too close to the second surface 12, which is beneficial for further reducing the recombination efficiency of electrons and holes. Simultaneously, it can also reduce parasitic absorption through a wider band gap, reducing light loss during transmission and improving the photoelectric conversion efficiency of the back contact cell.

[0120] In one specific embodiment, the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer 312 satisfies 3%≤X5≤35%, and X5 can specifically be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, etc.

[0121] When the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer 312 meets the requirement of 3% ≤ X5 ≤ 35%, the second intrinsic hydrogenated amorphous silicon oxide layer 312 ensures the lossless transmission of long-wavelength light, thereby reducing optical loss. This facilitates the subsequent reflection of long-wavelength light back to the substrate 1 for full absorption, which in turn helps improve the long-wavelength response and short-circuit current of the back contact cell. Simultaneously, the second intrinsic hydrogenated amorphous silicon oxide layer 312, the first intrinsic hydrogenated amorphous silicon oxide layer 311, and the antireflection layer 32 can form a refractive index gradient design, allowing more wavelengths of light to be transmitted to the substrate 1. This helps improve the short-circuit current of the back contact cell and enhances its photoelectric conversion efficiency.

[0122] In one specific implementation, such as Figure 1 and Figure 2 As shown, the antireflection layer 32 also includes at least one silicon nitride layer 321 (SiN:H), the refractive index of the silicon nitride layer 321 is R2, and R2 satisfies 1.9≤R2≤2.1.

[0123] In this embodiment, the antireflection layer 32 acts as a buffer between the air environment and the second passivation layer 31, adjusting the refractive index difference between them to form a better refractive index gradient design structure. This allows a complete four-layer antireflection passivation structure to be formed between the air environment and the hydrogenated silicon nitride layer 321, between the hydrogenated silicon nitride layer 321 and the second intrinsic hydrogenated amorphous silicon oxide layer 312, between the second intrinsic hydrogenated amorphous silicon oxide layer 312 and the first intrinsic hydrogenated amorphous silicon oxide layer 311, and between the first intrinsic hydrogenated amorphous silicon oxide layer 311 and the substrate 1. This improves the incident light effect and the absorption efficiency of the substrate 1, thereby increasing the short-circuit current of the back contact battery. Simultaneously, the hydrogenated silicon nitride layer 321 has good mechanical properties, protecting the second passivation layer 31 and the substrate 1 from damage by moisture or contaminants during subsequent packaging, transportation, and use, thus improving the working performance and lifespan of the back contact battery.

[0124] Optionally, the refractive index of the silicon nitride layer 321 can be 1.9, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.8, 1.99, 2, 2.01, 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.1, etc.

[0125] In one possible implementation, the thickness of the antireflection layer 32 is H3, and H3 satisfies 50nm≤H3≤95nm, specifically it can be 50nm, 51nm, 52nm, 53nm, 54nm, 55nm, 56nm, 57nm, 58nm, 59nm, 60nm, 61nm, 62nm, 63nm, 64nm, 65nm, 66nm, 67nm, 68nm, 69nm, 70nm, 71nm, 72nm, 73nm, 74nm, 75nm, 76nm, 77nm, 78nm, 79nm, 80nm, 81nm, 82nm, 83nm, 84nm, 85nm, 86nm, 87nm, 88nm, 89nm, 90nm, 91nm, 92nm, 93nm, 94nm, 95nm, etc.

[0126] In one specific implementation, such as Figure 1 and Figure 2 As shown, the first surface 11 includes a first region 111 and a second region 112 arranged alternately along the second direction y. A first passivation structure 2 is disposed in the first region 111. The back contact battery also includes a third passivation structure 4, which is disposed in the second region 112.

[0127] The third passivation structure 4 includes a tunneling oxide layer 41 and an N-type doped layer 42 stacked along the first direction x, with the N-type doped layer 42 connected to the side of the tunneling oxide layer 41 facing away from the substrate 1.

[0128] In this embodiment, a first passivation layer 21 and a P-type doped layer 22 are sequentially deposited in the first region 111 of the first surface 11, and a tunneling oxide layer 41 and an N-type doped layer 42 are sequentially deposited in the second region 112 of the first surface 11.

[0129] In this design, both the first passivation layer 21 and the tunneling oxide layer 41 saturate the dangling bonds on the surface of the substrate 1, forming chemical passivation to reduce the recombination rate of electrons and holes in the first region 111. The P-type doped layer 22 and the N-type doped layer 42 form a built-in electric field with the substrate 1, enabling selective hole transport in the first passivation structure 2 and selective electron transport in the third passivation structure 4. This allows electrons and holes to be effectively and partitioned, reducing the recombination probability of electrons and holes on the first surface 11 and improving carrier collection and transport efficiency. Simultaneously, by arranging the first region 111 and the second region 112 alternately along the second direction y, lateral electron and hole transport is facilitated, shortening the transport distance along the second direction y. This helps reduce the series resistance of the back-contact battery and improve the fill factor. Furthermore, the first passivation layer 21 uses hydrogenated amorphous silicon oxide, and the tunneling oxide layer 41 typically uses silicon dioxide, which reduces the parasitic absorption of long-wavelength light on the back side of the battery, thus improving the short-circuit current of the back-contact battery. Therefore, this design integrates heterojunction passivation and selective contact functions on the back of the battery, which helps to improve the optical and electrical performance of the back-contact battery, thereby improving the overall photoelectric conversion efficiency.

[0130] In one specific implementation, such as Figure 1 and Figure 2 As shown, the back contact battery also includes a transparent conductive layer 5. Along the first direction x, the transparent conductive layer 5 is connected to the side of the P-type doped layer 22 away from the first passivation layer 21 and the N-type doped layer 42 away from the tunneling oxide layer 41.

[0131] The back contact battery also includes a first electrode 6 and a second electrode 7. Along the first direction x, the first electrode 6 is connected to the side of the transparent conductive layer 5 away from the P-type doped layer 22, and the second electrode 7 is connected to the side of the transparent conductive layer 5 away from the N-type doped layer 42. Along the second direction y, the first electrode 6 and the second electrode 7 are arranged alternately and spaced apart.

[0132] In this embodiment, along the first direction x, the first electrode 6 can be located within the projection range of the first region 111, and the second electrode 7 can be located within the projection range of the second region 112, so that after holes and electrons move from the substrate 1 to the transparent conductive layer 5, they can be transversely transported, thereby flowing to the first electrode 6 and the second electrode 7 respectively, and the collected current can be transmitted to the corresponding gate line, which is beneficial to improving the current transmission efficiency.

[0133] The transparent conductive layer 5 includes a first conductive segment 51 and a second conductive segment 52 arranged alternately and spaced along the second direction y. The first electrode 6 is electrically connected to the P-type doped layer 22 through the first conductive segment 51, and the second electrode 7 is electrically connected to the N-type doped layer 42 through the second conductive segment 52. This allows electrons and holes to achieve efficient transport in their respective independent regions, avoiding electrical short circuits caused by electrons and holes in the same transparent conductive layer 5, thereby ensuring the stability and reliability of the back contact battery during operation.

[0134] An embodiment of this application also provides a preparation method, which includes:

[0135] A substrate 1 is provided; a first hydrogenated amorphous silicon oxide layer 211 is deposited on the first surface 11 using a first process gas; a second hydrogenated amorphous silicon oxide layer 212 is deposited on the first hydrogenated amorphous silicon oxide layer 211 using a second process gas; and a P-type doped layer 22 is deposited on the second hydrogenated amorphous silicon oxide layer 212 using a third process gas.

[0136] During the deposition process, the hydrogen dilution ratio of the first process gas is RH, and RH satisfies 8≤RH≤12, the first pressure is P1, and P1 satisfies 50pa≤P1≤180pa, and the first temperature is T1, and T1 satisfies 180℃≤T1≤230℃, so that the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212 satisfies X1>X2.

[0137] In this embodiment, during the deposition process, a first hydrogenated amorphous silicon oxide layer 211 can be deposited on the first surface 11, a second hydrogenated amorphous silicon oxide layer 212 can be deposited on the first hydrogenated amorphous silicon oxide layer 211, and a P-type doped layer 22 can be deposited on the second hydrogenated amorphous silicon oxide layer 212, thereby forming a first passivation structure 2 composed of a first passivation layer 21 and a P-type doped layer 22. This design effectively improves the passivation effect at the interface and reduces parasitic absorption at the interface, thereby increasing the open-circuit voltage and short-circuit current of the back contact battery. Furthermore, by setting the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212 as a stacked structure with a gradient oxygen doping ratio, it not only further improves the blocking effect on electrons and the transport effect on holes, thus better achieving selective carrier transport, but also allows long-wavelength light that is not absorbed by the substrate 1 to pass through without loss, optimizing optical performance, reducing parasitic absorption, and improving the effective absorption rate of the back contact battery for long-wavelength light, thereby improving the photoelectric conversion efficiency of the back contact battery.

[0138] Optionally, the first process gas includes silane (SiH4), carbon dioxide (CO2) or nitrous oxide (N2O), the second process gas includes silane (SiH4), hydrogen (H2), carbon dioxide (CO2) or nitrous oxide (N2O), and the third process gas includes diborane (B2H6).

[0139] The hydrogen dilution ratio of the first process gas during deposition satisfies 8 ≤ RH ≤ 12, specifically 8, 9, 10, 11, 12, etc., to create high hydrogen dilution conditions. This promotes the migration of silicon atoms and the formation of chemical bonds, thereby reducing the dangling bonds and defect density on the first surface 11, which is beneficial for achieving more stable and reliable chemical passivation. Simultaneously, the first pressure during deposition satisfies 50 Pa ≤ P1 ≤ 180 Pa, specifically 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa, 110 Pa, 120 Pa, 130 Pa, 140 Pa, 150 Pa, 160 Pa, 170 Pa, 180 Pa, etc., to ensure sufficient diffusion time for the process gas. This reduces the occurrence of pinholes, depressions, and other defects in the first passivation layer 21 during the forming process, thereby improving the passivation quality of the first passivation layer 21. Furthermore, the initial deposition temperature satisfies 180℃≤T1≤230℃, specifically 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, etc., to ensure a denser first passivation layer 21 during the forming process, thereby further optimizing the passivation effect. Therefore, by synergistically adjusting the hydrogen dilution ratio, the initial pressure, and the initial temperature, a favorable preparation environment can be created, resulting in the first passivation layer 21 having a lower defect density, higher density, and better electrical properties, which is beneficial for improving the product quality of back contact batteries.

[0140] In one specific embodiment, after the step of depositing a first hydrogenated amorphous silicon oxide layer 211 on the first surface 11 using a first process gas, the preparation method further includes:

[0141] A third hydrogenated amorphous silicon oxide layer 213 is deposited on the first hydrogenated amorphous silicon oxide layer 211 using a second process gas; a second hydrogenated amorphous silicon oxide layer 212 is deposited on the third hydrogenated amorphous silicon oxide layer 213 using a second process gas.

[0142] The oxygen doping ratios of the third hydrogenated amorphous silicon oxide layer 213, the first hydrogenated amorphous silicon oxide layer 211, and the second hydrogenated amorphous silicon oxide layer 212 satisfy X3 > X1 and X3 > X2.

[0143] In this embodiment, by depositing at least one third hydrogenated amorphous silicon oxide layer 213 with a higher oxygen doping ratio between the first hydrogenated amorphous silicon oxide layer 211 and the second hydrogenated amorphous silicon oxide layer 212, the oxygen doping ratio of the first passivation layer 21 first increases and then decreases, while the refractive index first decreases and then increases. This allows the third hydrogenated amorphous silicon oxide layer 213 to reflect light reaching the back of the battery back to the substrate 1 as much as possible, so that the substrate 1 can repeatedly absorb it. This helps to further reduce parasitic absorption, improve the utilization rate of long-wavelength light, and thus improve the long-wavelength response and short-circuit current of the back-contact battery. At the same time, the three hydrogenated amorphous silicon oxide layers can form a double barrier structure, with the barrier first increasing and then decreasing. This can not only accurately realize the effective transport of holes, but also further improve the blocking effect on electrons. Even if a small number of electrons manage to cross the first hydrogenated amorphous silicon oxide layer 211, they will be reflected back by the third hydrogenated amorphous silicon oxide layer 213, thereby helping to further reduce the recombination efficiency of electrons and holes at the interface.

[0144] In one specific embodiment, during the deposition of a first hydrogenated amorphous silicon oxide layer 211 on the first surface 11 using a first process gas, the preparation method further includes:

[0145] A first intrinsic hydrogenated amorphous silicon oxide layer 311 is deposited on the second surface 12 using a first process gas; a second intrinsic hydrogenated amorphous silicon oxide layer 312 is deposited on the first intrinsic hydrogenated amorphous silicon oxide layer 311 using a second process gas.

[0146] The oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer 311 and the second intrinsic hydrogenated amorphous silicon oxide layer 312 satisfies X4 < X5.

[0147] In this embodiment, during the deposition process, a first intrinsic hydrogenated amorphous silicon oxide layer 311 can be deposited on the second surface 12, and a second intrinsic hydrogenated amorphous silicon oxide layer 312 can be deposited on the first intrinsic hydrogenated amorphous silicon oxide layer 311, thereby forming a second passivation layer 31. This design effectively improves the passivation effect at the interface and reduces parasitic absorption at the interface, thereby increasing the open-circuit voltage and short-circuit current of the back contact battery. Furthermore, by setting the second passivation layer 31 as a stacked structure with an oxygen doping ratio gradient design, the loss of light during propagation can be further reduced, thus improving the photoelectric conversion efficiency of the back contact battery.

[0148] In one specific embodiment, after the step of depositing a second intrinsic hydrogenated amorphous silicon oxide layer 312 on the first intrinsic hydrogenated amorphous silicon oxide layer 311 using a second process gas, the preparation method further includes:

[0149] An antireflection layer 32 is deposited on the second intrinsic hydrogenated amorphous silicon oxide layer 312 using a fourth process gas.

[0150] During the deposition process, the silicon-nitrogen atom ratio in the fourth process gas is Si / N, and Si / N satisfies 0.5≤Si / N≤2.5. The hydrogen concentration in the fourth process gas is CH, and CH satisfies 15%≤CH≤50%. The second pressure is P2, and P2 satisfies 50pa≤P2≤200pa. The second temperature is T2, and T2 satisfies 170℃≤T2≤250℃.

[0151] In this embodiment of the application, during the deposition process, the first intrinsic hydrogenated amorphous silicon oxide layer 311 can cover the second surface 12, the second intrinsic hydrogenated amorphous silicon oxide layer 312 can cover the first intrinsic hydrogenated amorphous silicon oxide layer 311, and the antireflection layer 32 can cover the second hydrogenated amorphous silicon oxide layer 212, thereby forming a second passivation structure 3 composed of the first passivation layer 21 and the antireflection layer 32. This design allows the antireflective layer 32 to act as a buffer between the air environment and the second passivation layer 31, thus adjusting the refractive index difference between them. This results in a better refractive index gradient design structure, enabling the formation of a complete four-layer antireflective passivation structure between the air environment and the silicon nitride layer 321, between the silicon nitride layer 321 and the second intrinsic hydrogenated amorphous silicon oxide layer 312, between the second intrinsic hydrogenated amorphous silicon oxide layer 312 and the first intrinsic hydrogenated amorphous silicon oxide layer 311, and between the first intrinsic hydrogenated amorphous silicon oxide layer 311 and the substrate 1. This improves the incident light effect and the absorption efficiency of the substrate 1, thereby increasing the short-circuit current of the back contact battery. Simultaneously, the silicon nitride layer 321 possesses good mechanical properties, protecting the second passivation layer 31 and the substrate 1 from damage by moisture or contaminants during subsequent packaging, transportation, and use, thus improving the working performance and lifespan of the back contact battery.

[0152] Optionally, the fourth process gas includes silane (SiH4), ammonia (NH3), and hydrogen (H2).

[0153] The silicon-nitrogen atom ratio in the fourth process gas during deposition satisfies 0.5≤Si / N≤2.5, specifically 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc., so that the antireflection layer 32 has a high refractive index, which can achieve high light transmittance and low reflectivity when irradiated by sunlight. This is beneficial to improving the effective absorption rate of light and the photoelectric conversion efficiency of the back contact cell. In addition, the antireflection layer 32 can also have a large number of fixed positive charges, which can attract electrons and repel holes on the second surface 12, thereby reducing the recombination rate of the two and providing good field-effect passivation. Furthermore, the hydrogen concentration in the fourth process gas during deposition meets the requirement of 15% ≤ CH ≤ 50%, specifically 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc., to facilitate diffusion during deposition and heat treatment, thereby saturating dangling bonds, achieving chemical passivation, and reducing the recombination rate. Simultaneously, the second pressure during deposition meets the requirement of 50 Pa ≤ P2 ≤ 200 Pa, specifically 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa, 110 Pa, 120 Pa, 130 Pa, 140 Pa, 150 Pa, 160 Pa, 170 Pa, 180 Pa, 190 Pa, 200 Pa, etc., to ensure sufficient diffusion time for the process gas, thereby reducing pinholes, depressions, and other defects in the antireflective layer 32 during the forming process, and ultimately improving the passivation quality of the antireflective layer 32. Furthermore, the second deposition temperature satisfies 170℃≤T2≤250℃, specifically 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc., to ensure a more compact antireflection layer 32 during the molding process, thereby further optimizing the passivation effect. Therefore, by synergistically adjusting the silicon-nitrogen atomic ratio, hydrogen concentration, second pressure, and second temperature, a favorable preparation environment can be created, enabling the antireflection layer 32 to possess excellent optical properties and passivation effects, which is beneficial for improving the product quality of back contact batteries.

[0154] An embodiment of this application also provides a back-contact stacked battery, which includes a back-contact bottom battery and a perovskite top battery. The perovskite top battery is electrically connected to the front side of the back-contact bottom battery, and the back-contact bottom battery is any of the back-contact batteries described above.

[0155] In this embodiment, when the perovskite top cell and the back contact bottom cell are electrically connected on the front side to form a back contact tandem cell, the overall photoelectric conversion efficiency can be improved by utilizing the solar spectrum in different wavelength bands. Specifically, the perovskite top cell can use a wide bandgap to absorb high-energy short-wavelength photons to reduce light loss and increase open-circuit voltage, while the back contact bottom cell can use a narrow bandgap to absorb low-energy long-wavelength photons to reduce photothermal loss and increase current density. Thus, the photoelectric conversion efficiency of the back contact tandem cell can be improved through the synergistic effect of the perovskite top cell and the back contact bottom cell. Simultaneously, the back contact tandem cell also includes an interconnect layer located between the perovskite top cell and the back contact bottom cell along the thickness direction of the back contact tandem cell. This interconnect layer serves to connect and transmit current, facilitating current matching between the two cells and reducing series resistance, increasing the fill factor, and optimizing charge transfer efficiency.

[0156] Embodiments of this application also provide a photovoltaic module, which includes a cover plate, an encapsulation layer, and at least one battery string. The cover plate is connected to the battery string through the encapsulation layer, and the battery string includes a plurality of back-contact batteries as described in any of the above claims or back-contact stacked batteries as described in the above claims.

[0157] In this embodiment, the photovoltaic module may include multiple battery strings, which are electrically connected in series and / or parallel. The solar cells of each battery string can be the aforementioned back-contact cells or back-contact tandem cells. By employing a first passivation layer 21 and a P-type doped layer 22 made of a hydrogenated amorphous silicon oxide tandem structure, and a second passivation layer 31 and an anti-reflection layer 32 made of an intrinsic hydrogenated amorphous silicon oxide tandem structure, the passivation effect of the first surface 11 and the second surface 12 can be effectively improved, and parasitic absorption at the interface can be reduced. This can improve the open-circuit voltage and short-circuit current of the back-contact cells or back-contact tandem cells. Furthermore, the tandem structure designed with a gradient oxygen doping ratio can not only further improve the blocking effect on electrons and the transport effect on holes to better achieve selective transport of charge carriers, but also further widen the bandgap to improve the utilization rate of long-wavelength light, thereby improving the photoelectric conversion efficiency of the back-contact cells or back-contact tandem cells.

[0158] Optionally, the back contact battery can be electrically connected in the form of a single sheet or multiple segments to form multiple battery strings, and the multiple battery strings can be electrically connected in series and / or parallel to form a battery cell layer. Furthermore, back contact batteries include, but are not limited to, IBC batteries (Interdigitated Back Contact Battery), HBC batteries (Heterojunction Back Contact Battery), TBC batteries (TOPCon Back Contact Battery), or HPBC batteries (Hybrid Passivated Back Contact Battery), etc.

[0159] In one possible implementation, the cover plate may include a first cover plate and a second cover plate. The first cover plate may be located on the light-receiving side of the battery string, and the second cover plate may be located on the back-light side of the battery string. The encapsulation layer includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer may be located between the first cover plate and the battery string, and the second encapsulation layer may be located between the second cover plate and the battery string. That is, along the thickness direction of the photovoltaic module, the first cover plate, the first encapsulation layer, the battery string, the second encapsulation layer, and the second cover plate are stacked and pressed against each other.

[0160] The surfaces of the first and second cover plates facing the battery string can both have an uneven structure to increase the utilization rate of incident light. The first and second cover plates can be made of glass or plastic. The first and second encapsulation layers can connect the first cover plate and the battery string, and the second cover plate and the battery string, respectively, to encapsulate and protect the battery string. The first and second encapsulation layers can be made of one or more of the following: polyvinyl butyral film, ethylene-vinyl acetate copolymer film, polyvinyl octene co-elastomer film, and polyethylene terephthalate film.

[0161] The above description, based on the embodiments shown in the drawings, details the structure, features, and effects of this application. The above description is only a preferred embodiment of this application, but this application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of this application, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. A back contact cell, characterized in that, The back contact cell comprises: a substrate having a first surface and a second surface oppositely arranged along a first direction; a first passivation structure arranged on the first surface, the first passivation structure comprising a first passivation layer and a P-type doped layer arranged in a stack along the first direction, the P-type doped layer being connected to a side of the first passivation layer away from the substrate; the first passivation layer further comprises a first hydrogenated amorphous silicon oxide layer and a second hydrogenated amorphous silicon oxide layer arranged in a stack along the first direction, the second hydrogenated amorphous silicon oxide layer being located between the first hydrogenated amorphous silicon oxide layer and the P-type doped layer, the first hydrogenated amorphous silicon oxide layer having an oxygen content ratio X1, the second hydrogenated amorphous silicon oxide layer having an oxygen content ratio X2, and X1 and X2 satisfying X1>X2.

2. The back contact cell of claim 1, wherein, the first passivation layer further comprises a third hydrogenated amorphous silicon oxide layer, along the first direction, the third hydrogenated amorphous silicon oxide layer being located between the first hydrogenated amorphous silicon oxide layer and the second hydrogenated amorphous silicon oxide layer, the third hydrogenated amorphous silicon oxide layer having an oxygen content ratio X3, and X1, X2 and X3 satisfying X3>X1, X3>X2.

3. The back contact cell of claim 2, wherein, the oxygen content ratio of the first hydrogenated amorphous silicon oxide layer satisfies 9%≤X1≤12%, the oxygen content ratio of the second hydrogenated amorphous silicon oxide layer satisfies 6%≤X2≤8%, and the oxygen content ratio of the third hydrogenated amorphous silicon oxide layer satisfies 30%≤X3≤35%.

4. The back contact cell of claim 1, wherein, the first passivation layer has a refractive index R1, and R1 satisfies 3.2≤R1≤3.6, and the first passivation layer has an extinction coefficient K1, and K1 satisfies 0.5%≤K1≤1%.

5. The back contact cell of claim 1, wherein, the back contact cell further comprises a second passivation structure arranged on the second surface, the second passivation structure comprising a second passivation layer and an anti-reflection layer arranged in a stack along the first direction, the anti-reflection layer being connected to a side of the second passivation layer away from the substrate; the second passivation layer further comprises a first intrinsic hydrogenated amorphous silicon oxide layer and a second intrinsic hydrogenated amorphous silicon oxide layer arranged in a stack along the first direction, the second intrinsic hydrogenated amorphous silicon oxide layer being located between the first intrinsic hydrogenated amorphous silicon oxide layer and the anti-reflection layer, the first intrinsic hydrogenated amorphous silicon oxide layer having an oxygen content ratio X4, the second intrinsic hydrogenated amorphous silicon oxide layer having an oxygen content ratio X5, and X4 and X5 satisfying X4X5.

6. The back contact cell of claim 5, wherein, the oxygen content ratio of the first intrinsic hydrogenated amorphous silicon oxide layer satisfies 0.5%≤X4≤2%, and the oxygen content ratio of the second intrinsic hydrogenated amorphous silicon oxide layer satisfies 3%≤X5≤35%.

7. The back contact cell of claim 5, wherein, the anti-reflection layer further comprises at least one hydrogenated silicon nitride layer, the hydrogenated silicon nitride layer having a refractive index R2, and R2 satisfies 1.9≤R2≤2.

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8. The back contact cell according to any of claims 1-7, wherein, the first surface comprises first regions and second regions arranged alternately along a second direction, the first passivation structure being arranged on the first regions, and the back contact cell further comprises third passivation structures arranged on the second regions; The third passivation structure comprises a tunneling oxide layer and an N-type doped layer stacked along a first direction, and the N-type doped layer is connected to a side of the tunneling oxide layer away from the substrate.

9. The back contact cell of claim 8, wherein, The back contact cell further comprises a transparent conductive layer, along the first direction, the transparent conductive layer is connected to a side of the P-type doped layer away from the first passivation layer and a side of the N-type doped layer away from the tunneling oxide layer. The back contact cell further comprises a first electrode and a second electrode, along the first direction, the first electrode is connected to a side of the transparent conductive layer away from the P-type doped layer, and the second electrode is connected to a side of the transparent conductive layer away from the N-type doped layer, and along the second direction, the first electrode and the second electrode are arranged alternately and spaced apart.

10. A method of manufacture, characterized by, The preparation method comprises: providing a substrate, the substrate has a first surface and a second surface arranged oppositely along a first direction; depositing a first hydrogenated amorphous silicon oxide layer on the first surface by using a first process gas, the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer is X1; depositing a second hydrogenated amorphous silicon oxide layer on the first hydrogenated amorphous silicon oxide layer by using a second process gas, the oxygen doping ratio of the second hydrogenated amorphous silicon oxide layer is X2; depositing a P-type doped layer on the second hydrogenated amorphous silicon oxide layer by using a third process gas; during the deposition process, the hydrogen dilution ratio of the first process gas is RH, and RH satisfies 8≤RH≤12, the first pressure is P1, and P1 satisfies 50pa≤P1≤180pa, the first temperature is T1, and T1 satisfies 180℃≤T1≤230℃, so that the oxygen doping ratio of the first hydrogenated amorphous silicon oxide layer and the second hydrogenated amorphous silicon oxide layer satisfies X1>X2.

11. The method of claim 10, wherein, After the step of depositing the first hydrogenated amorphous silicon oxide layer on the first surface by using the first process gas, the preparation method further comprises: depositing a third hydrogenated amorphous silicon oxide layer on the first hydrogenated amorphous silicon oxide layer by using the second process gas, the oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer is X3; depositing the second hydrogenated amorphous silicon oxide layer on the third hydrogenated amorphous silicon oxide layer by using the second process gas; wherein the oxygen doping ratio of the third hydrogenated amorphous silicon oxide layer and the first hydrogenated amorphous silicon oxide layer and the second hydrogenated amorphous silicon oxide layer satisfies X3>X1, X3>X2.

12. The method of claim 10, wherein, During the process of depositing the first hydrogenated amorphous silicon oxide layer on the first surface by using the first process gas, the preparation method further comprises: depositing a first intrinsic hydrogenated amorphous silicon oxide layer on the second surface by using the first process gas, the oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer is X4; depositing a second intrinsic hydrogenated amorphous silicon oxide layer on the first intrinsic hydrogenated amorphous silicon oxide layer by using the second process gas, the oxygen doping ratio of the second intrinsic hydrogenated amorphous silicon oxide layer is X5; wherein the oxygen doping ratio of the first intrinsic hydrogenated amorphous silicon oxide layer and the second intrinsic hydrogenated amorphous silicon oxide layer satisfies X4X5.

13. The method of claim 12, wherein, After the step of depositing a second intrinsic hydrogenated amorphous silicon oxide layer on the first intrinsic hydrogenated amorphous silicon oxide layer using the second process gas, the preparation method further comprises: depositing an anti-reflective layer on the second intrinsic hydrogenated amorphous silicon oxide layer using a fourth process gas; During the deposition process, the silicon-nitrogen atomic ratio in the fourth process gas is Si / N, and Si / N satisfies 0.5≤Si / N≤2.5, the hydrogen concentration in the fourth process gas is CH, and CH satisfies 15%≤CH≤50%, the second pressure is P2, and P2 satisfies 50pa≤P2≤200pa, the second temperature is T2, and T2 satisfies 170℃≤T2≤250℃.

14. A back contact tandem cell, characterized by The back contact stacked cell comprises a back contact bottom cell and a perovskite top cell, the perovskite top cell is electrically connected with the front surface of the back contact bottom cell, and the back contact bottom cell is the back contact cell of any one of claims 1-9.

15. A photovoltaic module, characterized by, The photovoltaic module comprises a cover plate, an encapsulating layer, and at least one cell string, the cover plate is connected with the cell string through the encapsulating layer, and the cell string comprises a plurality of back contact cells of any one of claims 1-9 or the back contact stacked cell of claim 14.

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