TOPCon battery, preparation method thereof and photovoltaic module

Abstract

The embodiment of the invention discloses a TOPCon battery and a preparation method thereof, and a photovoltaic module, and the TOPCon battery comprises a substrate which is provided with a first surface facing incident light and a second surface opposite to the incident light; two or three tunneling passivation layers and contact layers arranged on the tunneling passivation layers are sequentially arranged on the second surface of the substrate; the tunneling passivation layer comprises a tunneling oxide layer and a phosphorus-doped layer; the contact layer is of a single-layer structure or a double-layer structure, and when the contact layer is of the single-layer structure, the contact layer is a light phosphorus-doped non-carbon-doped layer or a heavy phosphorus-doped non-carbon-doped layer; when the contact layer is of a double-layer structure, the contact layer sequentially comprises a light phosphorus-doped light carbon-doped layer and a heavy phosphorus-doped non-carbon-doped layer, or comprises a light phosphorus-doped non-carbon-doped layer and a heavy phosphorus-doped non-carbon-doped layer. According to the TOPCon battery provided by the invention, the multi-layer tunneling passivation structure and the contact layer are introduced, doping and carbon content are cooperatively regulated and controlled, silver penetration is effectively inhibited, contact resistance is reduced, interface passivation is optimized, and thus the open-circuit voltage and conversion efficiency of the TOPCon battery are improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically, to a TOPCon cell, its preparation method, and a photovoltaic module. Background Technology

[0002] With the continuous evolution of photovoltaic technology, high-efficiency solar cells have gradually become the core direction of industrial development. Among them, TOPCon (tunneling oxide passivated contact) cells based on N-type silicon substrates have become an important candidate for high-efficiency cell structures due to their excellent interface passivation performance and superior electron selective transport capability. TOPCon technology effectively suppresses minority carrier recombination while ensuring efficient carrier passage through the contact interface by depositing an ultrathin tunneling silicon oxide layer and a doped polycrystalline silicon layer on the silicon substrate surface, achieving dual optimization of photoelectric conversion efficiency, with a theoretical limit efficiency of up to 28.7%.

[0003] Currently, the mainstream technical solution mainly uses a single tunneling passivation contact structure, while some research has expanded to double or triple tunneling structures to further improve battery performance. For example, CN 119907353 A discloses a solar cell and photovoltaic module, including: a substrate, a first tunneling layer, a second doped semiconductor layer, a third doped semiconductor layer, and a third tunneling oxide layer. CN119277844 A proposes a solar cell with a triple tunneling structure, disclosing a solar cell and its fabrication method, as well as a photovoltaic module. The solar cell includes: a substrate; a first tunneling oxide layer; a first phosphorus doped layer; a second tunneling oxide layer; a second phosphorus doped layer; a third tunneling oxide layer; and a third phosphorus doped layer.

[0004] While multi-tunneling structures have made some progress in improving interface passivation and electron selectivity, how to further improve the open-circuit voltage (Voc) and reduce the contact resistance (ρc) to balance the fill factor (FF) and short-circuit current density (Jsc) remains a key issue that urgently needs to be addressed in the design of TOPCon devices. Therefore, it is imperative to propose a novel multilayer doped structure to optimize carrier concentration distribution, regulate doping activation effects, and improve overall optoelectronic performance. Summary of the Invention

[0005] This invention aims to address one of the technical problems in related technologies to a certain extent. To this end, embodiments of this invention propose a TOPCon battery that, by introducing a multilayer tunneling passivation structure and a contact layer, synergistically controls doping and carbon content, effectively suppressing silver penetration, reducing contact resistance, and optimizing interface passivation, thereby improving the open-circuit voltage and conversion efficiency of the TOPCon battery, and exhibiting good process compatibility and stability.

[0006] This invention also proposes a method for preparing a TOPCon battery.

[0007] This invention also proposes a photovoltaic module including TOPCon cells.

[0008] The technical solution adopted by this invention is: to provide a TOPCon battery, comprising: A substrate having a first surface facing the incident light and a second surface facing away from the incident light; The second side of the substrate is provided with two or three tunneling passivation layers, and a contact layer disposed on the tunneling passivation layers. The tunneling passivation layer includes a tunneling oxide layer and a phosphorus-doped layer; the contact layer is a single-layer structure or a double-layer structure, wherein: When it is a single-layer structure, the contact layer is a lightly phosphorus-doped but uncarbon-doped layer or a heavily phosphorus-doped but uncarbon-doped layer; When it is a double-layer structure, the contact layer sequentially includes a lightly phosphorus-doped and lightly carbon-doped layer and a heavily phosphorus-doped and undoped layer, or includes a lightly phosphorus-doped and undoped layer and a heavily phosphorus-doped and undoped layer.

[0009] The TOPCon battery provided by this invention introduces a two- or three-layer tunneling passivation layer structure and a contact layer in its structural design to solve key problems faced by existing TOPCon structures, such as high contact resistance, severe silver ion penetration, and insufficient interface passivation. Specifically, it brings the following beneficial effects: 1. Suppressing silver penetration and improving contact stability: By introducing carbon elements into the tunneling passivation layer and the contact layer, the carbon elements act as a barrier to silver diffusion in silicon, which can effectively suppress the penetration of silver ions, thereby significantly reducing the contact degradation problem caused by silver crystal erosion of the active layer after sintering and improving the long-term reliability of the battery.

[0010] 3. Reduce contact resistance and increase fill factor (FF): The heavily phosphorus-doped layer has a higher carrier concentration, which can enhance electron transport capability and significantly reduce the series resistance on the charge transport path, thereby reducing the overall contact resistance (ρc) and improving FF without affecting the passivation quality.

[0011] 3. High structural tunability and compatibility with different preparation processes: It provides a dual-layer or triple-layer tunneling passivation structure. In the triple-layer structure, the dual-layer heavy phosphorus and heavy carbon doping configuration improves the stability of the structure to high-temperature sintering and enhances the process window tolerance.

[0012] 4. Balancing high open-circuit voltage and low contact resistance: Although traditional single-layer heavily doped layers have strong conductivity, their interface passivation effect is poor. This invention optimizes the multi-layer passivation structure by dividing the functions: the outer layer is heavily doped with phosphorus to provide good conductivity, while the inner layer can be lightly doped to optimize the interface state density, thus achieving a balance between high Voc and low ρc.

[0013] 5. Improved battery conversion efficiency: The multi-layer structure design optimizes charge selectivity, carrier collection capability, and interface characteristics of metal contacts, significantly improving the overall electrical performance of the TOPCon structure. Ultimately, this helps to improve the photoelectric conversion efficiency of the battery and promote the industrialization of N-type high-efficiency batteries.

[0014] According to one embodiment of the present invention, when the tunneling passivation layer has a two-layer structure, the outermost phosphorus-doped layer is a heavily phosphorus-doped and heavily carbon-doped layer; when the tunneling passivation layer has a two-layer structure, the outermost phosphorus-doped layer is a heavily phosphorus-doped and heavily carbon-doped layer, which is used to form a higher carrier concentration gradient in the interface region near the contact layer, and to further suppress the interfacial recombination of carriers by controlling the band bending at the grain boundary through carbon elements, thereby improving the selective transport capability of carriers, and thus effectively reducing the contact resistance and increasing the open-circuit voltage.

[0015] When the tunneling passivation layer has a three-layer structure, the two outermost phosphorus-doped layers are both heavily phosphorus-doped and heavily carbon-doped layers. This three-layer structure enables stronger field-effect passivation and a better bandgap structure at the multiple tunneling interface, effectively improving minority carrier lifetime and reducing interface state density. Simultaneously, by deepening the doping and introducing carbon, the conductivity and thermal stability are further improved. This ensures efficient current extraction while maintaining excellent passivation performance, synergistically optimizing the cell's Voc, Jsc, and FF parameters.

[0016] According to one embodiment of the present invention, the activation concentration of phosphorus in the heavily phosphorus-doped carbon layer is 1E20~3E20 cm⁻¹. -3 The carbon doping concentration is 1E21~4E21cm. -3 This concentration design ensures carrier concentration while enhancing the suppression of silver ion penetration, thereby improving contact stability and battery life.

[0017] According to one embodiment of the present invention, the phosphorus-doped layer in the first tunneling passivation layer in the direction from the substrate to the contact layer is a lightly phosphorus-doped, undoped layer, or a lightly phosphorus-doped, lightly doped carbon layer: this configuration can optimize the interface passivation effect and tunneling transport performance, and improve the open-circuit voltage and device efficiency.

[0018] According to one embodiment of the present invention, the activation concentration of phosphorus in the first tunneling passivation layer is 2E20~5E20 cm⁻¹. -3 The carbon doping concentration is 9E20~2E21 cm⁻¹ -3 .

[0019] According to one embodiment of the present invention, the activation concentration of phosphorus in the lightly phosphorus-doped but carbon-free layer is 1E20~3E20 cm⁻¹. -3 ; and / or The activation concentration of phosphorus in the lightly phosphorus-doped carbon layer is 1E20~3E20 cm⁻¹. -3 The carbon doping concentration is 1E21~4E21cm. -3 ; and / or The activation concentration of phosphorus in the heavily phosphorus-doped but undoped layer is 1E20~4E20 cm⁻¹. -3 .

[0020] A method for preparing a TOPCon battery includes the following steps: 1) Provide a substrate having a first surface facing the incident light and a second surface facing away from the incident light; 2) Two or three tunneling passivation layers are sequentially formed on the second surface of the substrate, wherein the tunneling passivation layers include a tunneling oxide layer and a phosphorus doped layer; 3) A contact layer is formed on the surface of the tunneling passivation layer, wherein the contact layer is formed in one of the following two ways: When forming a single-layer contact layer, the single-layer contact layer is a lightly phosphorus-doped but uncarbon-doped layer or a heavily phosphorus-doped but uncarbon-doped layer; When a double contact layer is formed, the double contact layer is, in sequence, a lightly phosphorus-doped and lightly carbon-doped layer and a heavily phosphorus-doped and undoped layer, or in sequence, a lightly phosphorus-doped and undoped layer and a heavily phosphorus-doped and undoped layer.

[0021] According to an embodiment of the present invention, the method for forming a phosphorus-doped layer in the first tunneling passivation layer in the direction from the substrate to the contact layer in step 2 includes: A lightly phosphorus-doped, undoped carbon layer, or a lightly phosphorus-doped, lightly carbon-doped layer, is formed on the first tunneling oxide layer.

[0022] According to one embodiment of the present invention, in step 2, when the tunneling passivation layer is a two-layer structure, the outermost phosphorus-doped layer is a heavily phosphorus-doped and heavily carbon-doped layer. When the tunneling passivation layer has a three-layer structure, the two outermost phosphorus-doped layers are both heavily phosphorus-doped and carbon-doped layers.

[0023] A photovoltaic module includes a TOPCon cell as described above or a TOPCon cell prepared by any of the methods described above. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a schematic diagram of the TOPCon battery structure in Embodiment 1 of the present invention.

[0026] Figure 2 This is a schematic diagram of the TOPCon battery structure in Embodiment 2 of the present invention.

[0027] Explanation of the labels in the diagram: 1. Substrate; 2. First tunneling passivation layer; 3. Second tunneling passivation layer; 4. Third tunneling passivation layer; 5. Contact layer; 21. First tunneling oxide layer; 22. Lightly doped layer; 31. Second tunneling oxide layer; 32. First heavily doped layer; 41. Third tunneling oxide layer; 42. Second doped layer. Detailed Implementation

[0028] This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. Of course, they are merely examples and are not intended to limit this application. Furthermore, reference numerals and / or letters may be repeated in different instances. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0030] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of this application. Unless otherwise specified, all masses of the listed ingredients are given as the content of the active substance and therefore do not include solvents or byproducts that may be present in commercially available materials. The term "percentage by mass" may be expressed by the symbol "%".

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0032] Unless otherwise stated, a singular term may include a plural term and should not be understood as having a quantity of one.

[0033] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means additional steps and components that may be added without affecting the final result. The term “comprising” also includes the terms “composed of” and “substantially composed of.” The compositions and methods / processes of this application comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0034] The terms "preferred," "more preferably," etc., used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0035] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0036] This embodiment provides a TOPCon cell, including a substrate 1, which is an n-type silicon wafer having a first side facing incident light and a second side facing away from incident light. The first side is the light-receiving side of the cell, typically forming a p-type emitting region structure to absorb sunlight and generate charge carriers. The second side is provided with passivation and contact structures to achieve efficient minority carrier passivation and selective collection of charge carriers.

[0037] Furthermore, a tunneling passivation layer and a contact layer 5 are sequentially disposed on the second surface of the substrate 1, wherein the tunneling passivation layer is a double-layer or triple-layer structure. The tunneling passivation layer includes at least one tunneling oxide layer and at least one phosphorus-doped layer. The tunneling oxide layer is an ultrathin silicon oxide layer with a thickness ranging from 1.2 nm to 2.0 nm. The phosphorus-doped layer is made of microcrystalline silicon or polycrystalline silicon.

[0038] Furthermore, the phosphorus-doped layer of the tunneling passivation layer can be a lightly phosphorus-doped and lightly carbon-doped layer, a lightly phosphorus-doped and undoped layer, or a heavily phosphorus-doped and heavily carbon-doped layer, the specific structure of which is determined by the number and position of the passivation layers. From the substrate 1 to the contact layer 5, the first phosphorus-doped layer is usually a lightly doped structure, which helps to maintain the passivation effect of the oxide layer interface; the outermost phosphorus-doped layer is a heavily phosphorus-doped and heavily carbon-doped structure, which can improve the interface stability through a higher carrier concentration and the introduction of carbon elements.

[0039] Furthermore, when the number of tunneling passivation layers is two, each tunneling oxide layer includes a tunneling oxide layer and a phosphorus-doped layer, with the outermost phosphorus-doped layer being a heavily phosphorus-doped and heavily carbon-doped layer. In this structure, the heavily phosphorus-doped and heavily carbon-doped layers are located close to the contact layer 5 to form a higher electron concentration gradient at the contact interface, effectively reducing the recombination rate and improving the selective transport capability of charge carriers.

[0040] Furthermore, combined Figure 1 As shown, the dual tunneling structure consists of a substrate 1, a first tunneling passivation layer 2, a second tunneling passivation layer 3, and a contact layer 5, arranged sequentially from the first to the second side. The first tunneling passivation layer 2 includes a first tunneling oxide layer 21 and a lightly doped layer 22, which is either a lightly phosphorus-doped and lightly carbon-doped layer or a lightly phosphorus-doped but undoped layer. The second tunneling passivation layer 3 includes a second tunneling oxide layer 31 and a first heavily doped layer 32, which is a heavily phosphorus-doped and heavily carbon-doped layer.

[0041] In this embodiment, the dual-tunneling TOPCon cell structure includes the following eight types: Structure 1: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon layer.

[0042] Structure 2: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Heavily phosphorus-doped and undoped carbon layer.

[0043] Structure 3: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer.

[0044] Structure 4: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon layer + Heavily phosphorus-doped and undoped carbon layer.

[0045] Structure 5: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and undoped layer.

[0046] Structure 6: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Heavily phosphorus-doped and undoped layer.

[0047] Structure 7: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and lightly carbon-doped layer + Heavily phosphorus-doped and undoped layer.

[0048] Structure 8: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and undoped layer + Heavily phosphorus-doped and undoped layer.

[0049] Furthermore, when the number of tunneling passivation layers is three, each tunneling passivation layer includes a tunneling oxide layer and a phosphorus doped layer, and the two outermost phosphorus doped layers are both heavily phosphorus-doped and heavily carbon-doped layers.

[0050] Furthermore, combined Figure 2 As shown, the three-tunneling passivation structure consists of a substrate 1, a first tunneling passivation layer 2, a second tunneling passivation layer 3, a third tunneling passivation layer 4, and a contact layer 5, arranged sequentially from the first to the second side. The first tunneling passivation layer 2 comprises a first tunneling oxide layer 21 and a lightly doped layer 22, where the lightly doped layer 22 is either a lightly phosphorus-doped and lightly carbon-doped layer or a lightly phosphorus-doped but undoped layer. The second tunneling passivation layer 3 comprises a second tunneling oxide layer 31 and a first heavily doped layer 32, where the first heavily doped layer 32 is a heavily phosphorus-doped and heavily carbon-doped layer. The third tunneling passivation layer 4 comprises a third tunneling oxide layer 41 and a second heavily doped layer 42, where the second heavily doped layer 42 is a heavily phosphorus-doped and heavily carbon-doped layer.

[0051] This design can form a composite passivation field effect at multiple tunneling interfaces, and introduce carbon elements to control the band structure, reduce the interface state density, improve thermal stability and conductivity, and ultimately improve the minority carrier lifetime, open circuit voltage (Voc), short circuit current (Jsc) and fill factor (FF) of the battery.

[0052] In this embodiment, the three-tunnel TOPCon cell structure includes the following eight types: Structure 9: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Phosphorus-doped and undoped carbon layer.

[0053] Structure 10: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Heavily phosphorus-doped and undoped carbon layer.

[0054] Structure 11: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer.

[0055] Structure 12: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon layer + Heavily phosphorus-doped and undoped carbon layer.

[0056] Structure 13: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Phosphorus-doped and undoped layer.

[0057] Structure 14: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Heavily phosphorus-doped and undoped layer.

[0058] Structure 15: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and lightly carbon-doped layer + Heavily phosphorus-doped and undoped layer.

[0059] Structure 16: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and undoped layer + Heavily phosphorus-doped and undoped layer.

[0060] Among them, the first tunneling oxide layer 21, the second tunneling oxide layer 31 and the third tunneling oxide layer 41 are all ultrathin silicon oxide.

[0061] Furthermore, the doping concentration of the phosphorus-doped layer is set according to the layer type. Specifically, the activation concentration of phosphorus in the lightly phosphorus-doped but undoped carbon layer is 1E20~3E20 cm⁻¹. -3 The activation concentration of phosphorus in the lightly phosphorus-doped and lightly carbon-doped layer is 1E20~3E20 cm⁻¹. -3 The carbon doping concentration is 1E21~4E21cm. -3 The activation concentration of phosphorus in the heavily phosphorus-doped, undoped layer is 1E20~4E20 cm⁻³; the activation concentration of phosphorus in the heavily phosphorus-doped, heavily doped carbon layer is 1E20~3E20 cm⁻³. -3 The carbon doping concentration is 1E21~4E21cm. -3 The doping concentration is achieved by adjusting the flow rate of the reaction gas and the deposition time during the chemical vapor deposition process. The precursor gas for phosphorus can be phosphine (PH3), trimethyl phosphate (TMP), etc., and the precursor gas for carbon can be methane (CH4), carbon dioxide (CO2), etc.

[0062] Furthermore, the contact layer 5 is a conductive structure formed on the outside of the tunneling passivation layer, used to form an ohmic contact with the external metal electrode. The contact layer 5 can be a single-layer or double-layer structure. When it is a single-layer structure, it is either a lightly phosphorus-doped but undoped carbon layer or a heavily phosphorus-doped but undoped carbon layer. When it is a double-layer structure, it sequentially includes a lightly phosphorus-doped and lightly carbon-doped layer followed by a heavily phosphorus-doped but undoped carbon layer, or a lightly phosphorus-doped but undoped carbon layer followed by a heavily phosphorus-doped but undoped carbon layer. This structure can be flexibly adjusted according to the conductivity and passivation capability requirements, effectively controlling the contact resistance and thermal stability.

[0063] Furthermore, this application also provides a method for preparing a TOPCon battery, comprising the following steps: 1) A silicon substrate 1 is provided, the silicon substrate 1 having a first surface facing the incident light and a second surface facing away from the incident light; 2) A tunneling passivation layer is sequentially formed on the second surface of the substrate 1, including forming a tunneling oxide layer with a thickness of 1.2~2.0 nm and at least one phosphorus doped layer. The phosphorus doped layer can be formed by plasma enhanced chemical vapor deposition (PECVD) or low pressure chemical vapor deposition (LPCVD) process. 3) A contact layer 5 is formed on the surface of the tunneling passivation layer, and the formation method includes selecting an appropriate doping concentration and precursor gas type.

[0064] Furthermore, in step 2, the first phosphorus-doped layer can be a lightly phosphorus-doped but undoped layer or a lightly phosphorus-doped and lightly carbon-doped layer. This layer is in direct contact with the tunneling oxide layer, which is beneficial for maintaining the passivation effect of the oxide layer and optimizing the charge transport performance.

[0065] Furthermore, if the tunneling passivation layer has a two-layer structure, a heavily phosphorus-doped and heavily carbon-doped layer is formed on the tunneling oxide layer; if it has a three-layer structure, a lightly doped layer 22 and two heavily phosphorus-doped and heavily carbon-doped layers are sequentially formed on the tunneling oxide layer. The layers form a gradual transition through atomic diffusion, and the overall structure exhibits excellent passivation and transport capabilities.

[0066] Furthermore, this application also relates to a photovoltaic module, which includes at least one of the aforementioned TOPCon cell units. The TOPCon cells can be packaged in series and parallel to form a standard cell module and integrated through structures such as glass, encapsulation film, and backsheet. It features high efficiency and high stability and is suitable for rooftop, ground-mounted power stations and integrated photovoltaic and energy storage systems. Example 1

[0067] This embodiment provides a TOPCon battery, the specific structure of which is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and lightly carbon-doped layer + Heavily phosphorus-doped and undoped layer Contact layer 5.

[0068] Specifically, the TOPCon cell uses an n-type monocrystalline silicon wafer as substrate 1. The selected silicon wafer has a (100) crystal orientation, a thickness of 130 micrometers, and a resistivity of 1~7 Ω·cm. After the silicon wafer undergoes a standard RCA cleaning process to remove surface impurities and contaminants, it is placed in a graphite boat for later use.

[0069] Next, the first tunneling oxide layer is deposited. This oxide layer is an ultrathin silicon oxide layer, which is deposited using a plasma-assisted deposition process. The reaction gas is nitrous oxide (N2O) with a flow rate of 15000 sccm, a gas pressure of 1900 mtorr, a deposition temperature of 430℃, a deposition power of 10000 W, an RF on / off ratio of 2 ms:150 ms, and a deposition time of 95 s, forming an ultrathin silicon oxide layer to achieve effective carrier tunneling transport and surface passivation.

[0070] Then, a first phosphorus-doped layer, namely a lightly phosphorus-doped and lightly carbon-doped amorphous silicon layer, is deposited on the first tunneling oxide layer 21. Plasma-enhanced chemical vapor deposition (PECVD) is used, with the reaction gases being SiH4, H2, PH3 and CH4 in a flow ratio of 4500 sccm:10000 sccm:300 sccm:300 sccm, a gas pressure of 3500 mtorr, a substrate temperature of 430℃, a deposition power of 5000 W, an RF on / off ratio of 3 ms:45 ms, and a deposition time of 200 s.

[0071] A second tunneling oxide layer 31 is deposited on the lightly phosphorus-doped and lightly carbon-doped layer. The oxidation process parameters are the same as those of the first tunneling oxide layer 21, but the deposition time is 35s, forming a second tunneling silicon oxide layer. This further constructs a double tunneling interface structure to enhance minority carrier lifetime and bandgap modulation.

[0072] Subsequently, a second phosphorus-doped layer was deposited, which was a heavily phosphorus-doped and heavily carbon-doped amorphous silicon thin film. SiH4, H2, PH3, and CH4 were used as reactant gases, with flow rates of 4500 sccm: 10000 sccm: 1000 sccm: 3000 sccm, respectively. The deposition temperature was 430℃, the gas pressure was 3500 mtorr, the deposition power was 10000 W, the RF on / off ratio was 3 ms: 45 ms, and the deposition time was 400 s.

[0073] Contact layer 5 employs a bilayer structure. First, a lightly phosphorus-doped and lightly carbon-doped amorphous silicon film is deposited. The reactant gas flow rates are SiH4: 4500 sccm, H2: 10000 sccm, PH3: 200 sccm, and CH4: 200 sccm. The deposition power is 5000 W, the RF on / off ratio is 3 ms:45 ms, and the deposition time is 100 s. Subsequently, a heavily phosphorus-doped and undoped amorphous silicon film is deposited. The reactant gases are SiH4, H2, and PH3, with flow rates of 4500 sccm:10000 sccm:600 sccm, and a CH4 flow rate of 0 sccm. All other parameters remain the same, and the deposition time is 100 s. This bilayer structure design aims to balance low contact resistance with good chemical stability.

[0074] After completing the silicon thin film stack structure, a mask layer is deposited on it to protect the pattern. The deposition conditions are as follows: substrate 1 temperature 400℃, reaction gas is N2O and SiH4 with a flow ratio of 15000sccm:3500sccm, gas pressure is 1900mtorr, power is 10000W, RF on / off ratio is 2ms:200ms, and deposition time is 120s.

[0075] Subsequently, a high-temperature crystallization annealing treatment was performed at a temperature of 930°C for 30 minutes to transform the deposited amorphous silicon film into a polycrystalline state, thereby improving its conductivity and structural stability.

[0076] After crystallization, RCA cleaning is used to remove surface impurities, while wet etching is used to remove the surface silicon oxide layer and ineffective deposited layer, and a 5nm aluminum oxide layer is deposited on the front side for further passivation.

[0077] Next, silicon nitride anti-reflective films are deposited on the front and back sides of the battery, with the front film thickness being about 70nm and the back film thickness being about 80nm, to improve light absorption and encapsulation compatibility.

[0078] The iVoc of the sample was tested using a Sinton tester, and the result was 745mV, indicating that the structure has excellent passivation and charge-selective transport properties.

[0079] Finally, metal grid lines were printed on the back using screen printing and then sintered at a temperature of 680℃ to form an ohmic contact.

[0080] The performance parameters of the TOPCon battery obtained from the test are as follows: battery efficiency is 25.80%, open circuit voltage Voc is 740mV, short circuit current Isc is 15.9mA, fill factor FF is 83.8%. All performance indicators are stable, the structure is reliable, and it has good prospects for industrial application. Example 2

[0081] This embodiment provides a TOPCon battery with a dual tunneling structure, the specific structure of which is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer.

[0082] Specifically, the TOPCon cell uses an n-type monocrystalline silicon wafer as substrate 1. The silicon wafer has a (100) crystal orientation, a thickness of 130 micrometers, and a resistivity range of 1~7 Ω·cm. After standard chemical cleaning (RCA) treatment, the silicon wafer is placed in a graphite boat for subsequent deposition steps.

[0083] First, a first tunneling oxide layer, namely the first silicon oxide layer, is deposited on the surface of silicon substrate 1 using a plasma-assisted deposition process. The reactant gas is nitrous oxide (N2O), with a flow rate of 15000 sccm, a pressure of 1900 mtorr, a deposition temperature of 400℃, a deposition power of 10000 W, an RF on / off ratio of 2 ms:150 ms, and a deposition time of 95 s. This layer is an ultra-thin tunneling silicon oxide layer, used to achieve efficient carrier tunneling and provide passivation.

[0084] Next, a lightly phosphorus-doped, undoped amorphous silicon thin film was deposited on the oxide layer as the first phosphorus-doped layer. The deposition conditions for this layer were as follows: the flow rates of the reactive gases SiH4, H2, PH3, and CH4 were 4500 sccm, 10000 sccm, 300 sccm, and 0 sccm, respectively; the deposition temperature was 400℃; the gas pressure was 3500 mtorr; the deposition power was 5000 W; the RF on / off ratio was 3 ms:45 ms; and the deposition time was 200 s. This layer provides a low defect density interface and suitable carrier transport capability.

[0085] Subsequently, a second tunneling oxide layer 31 was deposited on top of it, with process conditions basically the same as those for the first tunneling oxide layer 21: deposition temperature of 400℃, gas of N2O at a flow rate of 15000 sccm, gas pressure of 1900 mtorr, deposition power of 10000 W, RF on / off ratio of 2 ms:50 ms, and deposition time of 35 s. This layer further enhances charge-selective transport, forming a double-tunneling structure.

[0086] Next, a heavily phosphorus- and carbon-doped amorphous silicon film was deposited as the second phosphorus-doped layer. The reactant gases used in this layer were SiH2, H2, PH3, and CH4, with flow rates of 4500 sccm, 10000 sccm, 1000 sccm, and 3000 sccm, respectively. The substrate temperature was 400℃, the gas pressure was 3500 mtorr, the deposition power was 10000 W, the RF on / off ratio was 3 ms:45 ms, and the deposition time was 400 s. This layer forms a high carrier concentration region, and the band structure is effectively controlled through heavy carbon doping.

[0087] As contact layer 5, a lightly phosphorus-doped and lightly carbon-doped amorphous silicon layer and a heavily phosphorus-doped and undoped amorphous silicon layer are further deposited sequentially on the above structure to form a double-layer contact structure. The process parameters are as follows: Lightly phosphorus-doped and lightly carbon-doped layers: SiH4, H2, PH3, CH4 flow rates of 4500 sccm, 10000 sccm, 200 sccm, and 200 sccm, respectively; substrate temperature 400℃; gas pressure 3500 mtorr; deposition power 5000 W; RF on / off ratio 3 ms: 45 ms; deposition time 100 s. Heavy phosphorus-doped but carbon-free layer: SiH4, H2, and PH3 flow rates are 4500 sccm, 10000 sccm, and 600 sccm, respectively, CH4 flow rate is 0 sccm, all other parameters are the same, and the deposition time is 100 s.

[0088] The contact layer 5 combination has both good conductivity and stability, which helps to reduce contact resistance and ensure long-term operational reliability.

[0089] After completing the above film deposition, a mask layer is deposited on the overall structure to achieve pattern protection. The deposition conditions are as follows: substrate 1 temperature 400℃, reactant gases N2O and SiH4 with a flow rate ratio of 15000 sccm:3500 sccm, gas pressure 1900 mtorr, power 10000 W, RF on / off ratio 2 ms:200 ms, and deposition time 120 s.

[0090] Subsequently, a high-temperature crystallization annealing treatment is performed at a temperature of 930°C for approximately 30 minutes, which transforms the deposited amorphous silicon film into a polycrystalline or nanocrystalline structure, thereby improving its electrical properties and interface compatibility.

[0091] After annealing, the ineffective deposited layer on the surface is removed by wet etching, and a 5nm thick aluminum oxide passivation layer is deposited on the front side of the battery to further improve the minority carrier lifetime and surface passivation effect.

[0092] Silicon nitride is deposited on the front and back sides as an anti-reflection layer and a passivation protection layer, respectively, with film thicknesses of 70nm on the front side and 80nm on the back side, improving optical absorption efficiency and packaging compatibility.

[0093] The iVoc value of the battery sample was measured to be 744.5 mV using a Sinton tester, indicating that the device structure has good passivation effect and low carrier recombination rate.

[0094] Finally, metal grid lines are screen-printed on the back of the battery and sintered to form metal contacts at a temperature of 680°C.

[0095] Performance tests on the TOPCon battery showed a battery efficiency of 25.82%, an open-circuit voltage (Voc) of 740mV, a short-circuit current (Isc) of 15.88mA, and a fill factor (FF) of 84.0%. This structure features mature technology, excellent device performance, and is suitable for mass production and industrialization. Example 3

[0096] The difference between this embodiment and embodiment 2 is that the TOPCon battery structure in this embodiment is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon contact layer 5 (single layer), the difference being that the 6th layer (contact layer 5) is a single layer of phosphorus-doped and undoped carbon.

[0097] The specific steps for preparing this layer are as follows: the substrate temperature is 400℃; the flow rates of the reaction gases SiH4, H2, PH3, and CH4 are 4500 sccm, 10000 sccm, 400 sccm, and 0 sccm, respectively; the gas pressure is 3500 mtorr; the deposition power is 5000 W; the RF on / off ratio is 3 ms: 45 ms; and the deposition time is 120 s. Example 4

[0098] The difference between this embodiment and embodiment 2 is that the TOPCon battery structure in this embodiment is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Heavily phosphorus-doped and undoped carbon contact layer 5 (single layer), the difference being that the 6th layer (contact layer 5) is a single layer of heavily phosphorus-doped and undoped carbon.

[0099] The specific steps for preparing this layer are as follows: the substrate temperature is 430℃; the flow rates of the reaction gases SiH4, H2, PH3, and CH4 are 4500 sccm, 10000 sccm, 800 sccm, and 0 sccm, respectively; the gas pressure is 3500 mtorr; the deposition power is 10000 W; the RF on / off ratio is 3 ms: 45 ms; and the deposition time is 150 s. Example 5

[0100] The difference between this embodiment and embodiment 2 is that the TOPCon battery structure in this embodiment is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon layer + Heavily phosphorus-doped and undoped carbon layer (double contact layer 5).

[0101] The difference lies in the fact that the sixth layer is a two-layer contact structure, consisting of a lightly phosphorus-doped but undoped layer and a heavily phosphorus-doped but undoped layer.

[0102] The specific preparation steps of this layer are as follows: Lightly phosphorus-doped but undoped carbon layer: substrate 1 temperature 400℃; SiH4: 4500sccm, H2: 10000sccm, PH3: 200sccm, CH4: 0sccm; gas pressure 3500mtorr; power 5000W, RF on / off ratio 3ms:45ms; deposition time 80s.

[0103] The parameters of the heavily phosphorus-doped but undoped layer are the same as in Example 4. Example 6

[0104] The difference between this embodiment and embodiment 3 is that the TOPCon battery structure in this embodiment is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and undoped carbon contact layer 5 (single layer), the difference being that the third layer is a lightly phosphorus-doped and lightly carbon-doped layer, and the contact layer 5 is a single layer of lightly phosphorus-doped and undoped carbon.

[0105] The specific steps for preparing the third layer are as follows: the substrate temperature is 430℃; the flow rates of the reaction gases SiH4, H2, PH3, and CH4 are 4500 sccm, 10000 sccm, 300 sccm, and 300 sccm, respectively; the gas pressure is 3500 mtorr; the deposition power is 5000 W; the RF on / off ratio is 3 ms: 45 ms; and the deposition time is 200 s.

[0106] The deposition parameters for contact layer 5 are the same as in Example 3. Example 7

[0107] The difference between this embodiment and embodiment 4 is that the TOPCon battery structure in this embodiment is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Heavily phosphorus-doped and undoped carbon contact layer 5 (single layer), the difference being that the third layer is a lightly phosphorus-doped and lightly carbon-doped layer.

[0108] The preparation steps for the third layer are the same as in Example 6, and the deposition parameters for the contact layer 5 are the same as in Example 4. Example 8

[0109] The difference between this embodiment and embodiment 5 is that the TOPCon battery structure in this embodiment is as follows: The structure consists of a silicon substrate 1, a first tunneling oxide layer 21, a lightly phosphorus-doped and lightly carbon-doped layer, a second tunneling oxide layer 31, a heavily phosphorus-doped and heavily carbon-doped layer, a lightly phosphorus-doped and undoped carbon layer, and a heavily phosphorus-doped and undoped carbon layer (double contact layer 5). The difference is that the third layer is a lightly phosphorus-doped and lightly carbon-doped layer. The preparation steps of this third layer are the same as in Example 6, and the two contact structure parameters of the sixth layer are the same as the deposition conditions of the two layers in Example 5. Example 9

[0110] This embodiment provides a TOPCon battery with a three-tunnel structure, the specific structure of which is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and lightly carbon-doped layer + Heavily phosphorus-doped and undoped layer.

[0111] Specifically, the battery uses an n-type (100) oriented silicon wafer as substrate 1, the silicon wafer having a thickness of 130 micrometers and a resistivity of 1~7 Ω·cm. The fabrication steps of this TOPCon battery are as follows: 1. Place the cleaned silicon wafer into the graphite boat and then place it in the PECVD reaction chamber.

[0112] 2. Deposit the first tunneling oxide layer 21, wherein the silicon oxide is an ultrathin silicon oxide layer. During deposition, the substrate temperature is 430°C, the reaction gas is nitrous oxide (N2O), the gas flow rate is 15000 sccm, the gas pressure is 1900 mtorr, the deposition power is 10000 W, the RF on / off ratio is 2 ms: 150 ms, and the deposition time is 95 s.

[0113] 3. A first lightly phosphorus-doped and lightly carbon-doped layer, specifically an amorphous silicon thin film structure, is deposited on the first tunneling oxide layer 21. The flow rate ratio of the reaction gases SiH4, H2, PH3, and CH4 is 4500 sccm: 10000 sccm: 300 sccm: 300 sccm. The substrate temperature is 430℃, the gas pressure is 3500 mtorr, the deposition power is 5000 W, the RF on / off ratio is 3 ms: 45 ms, and the deposition time is 200 s.

[0114] 4. Deposit the second tunneling oxide layer 31 under the following conditions: substrate 1 temperature 430℃, N2O flow rate 15000 sccm, gas pressure 1900 mtorr, deposition power 10000 W, RF on / off ratio 2 ms: 50 ms, and deposition time 35 s.

[0115] 5. A first heavily phosphorus-doped and heavily carbon-doped layer is deposited on the second tunneling oxide layer 31. The reaction gas flow rates are: SiH4: 4500 sccm, H2: 10000 sccm, PH3: 1000 sccm, CH4: 3000 sccm; the substrate temperature is 430℃, the gas pressure is 3500 mtorr, the deposition power is 10000 W, the RF on / off ratio is 3ms:45ms, and the deposition time is 100s.

[0116] 6. Continue to deposit the third tunneling oxide layer 41 at a deposition temperature of 400℃, with N2O gas at a flow rate of 15000 sccm, a gas pressure of 1900 mtorr, a deposition power of 10000 W, an RF on / off ratio of 2 ms: 50 ms, and a deposition time of 20 s.

[0117] 7. Deposit a second heavily phosphorus-doped and heavily carbon-doped layer on the third tunneling oxide layer 41. The reaction gases are SiH4: 4500 sccm, H2: 10000 sccm, PH3: 1000 sccm, and CH4: 3000 sccm. The substrate temperature is 430℃, the gas pressure is 3500 mtorr, the deposition power is 10000 W, the RF on / off ratio is 3ms:45ms, and the deposition time is 300s.

[0118] 8. A double contact layer 5 is sequentially deposited on it. The first layer is a lightly phosphorus-doped and lightly carbon-doped amorphous silicon thin film. The reaction gas ratio is SiH4: 4500 sccm, H2: 10000 sccm, PH3: 200 sccm, CH4: 200 sccm. The substrate temperature is 430℃, the gas pressure is 3500 mtorr, the deposition power is 5000 W, the RF on / off ratio is 3ms:45ms, and the deposition time is 100s.

[0119] 9. The second contact layer 5 is a heavily phosphorus-doped, undoped carbon amorphous silicon thin film with a gas ratio of SiH4: 4500 sccm, H2: 10000 sccm, PH3: 600 sccm, CH4: 0 sccm; substrate 1 temperature 430℃, gas pressure 3500 mtorr, deposition power 5000 W, RF on / off ratio 3 ms: 45 ms, deposition time 100 s.

[0120] 10. Deposit a mask layer on the above film layer. The reactant gases are N2O and SiH4, with flow rates of 15000 sccm and 3500 sccm, respectively. The substrate temperature is 400℃, the gas pressure is 1900 mtorr, the deposition power is 10000 W, the RF on / off ratio is 2ms:200ms, and the deposition time is 120s.

[0121] 11. The deposited sample is subjected to high-temperature crystallization annealing treatment at a temperature of 930℃ for 30 minutes.

[0122] 12. Perform RCA cleaning on the sample to remove the wrapped area and the surface silicon oxide layer; then deposit an aluminum oxide passivation layer of about 5 nm on the front side.

[0123] 13. Silicon nitride films are deposited on the front and back sides respectively as anti-reflection and passivation films, with a thickness of 70nm on the front side and 80nm on the back side.

[0124] 14. The open-circuit voltage was tested using a Sinton tester, and the measured iVoc was 746mV.

[0125] 15. Perform screen printing and sintering processes to print metal grid lines on the back side, with a sintering temperature of 680℃.

[0126] 16. Finally, the battery performance was tested. The test results showed that the battery efficiency was 25.86%, the open circuit voltage Voc was 741mV, the short circuit current Isc was 15.9mA, and the fill factor FF was 83.9. Example 10

[0127] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Phosphorus-doped and undoped carbon contact layer 5 (single layer). Example 11

[0128] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Heavily phosphorus-doped and undoped carbon contact layer 5 (single layer). Example 12

[0129] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and undoped carbon layer + Heavily phosphorus-doped and undoped carbon layer (double contact layer 5). Example 13

[0130] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily doped carbon layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily doped carbon layer / Lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer (double contact layer 5). Example 14

[0131] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Phosphorus-doped and non-carbon-doped contact layer 5 (single layer). Example 15

[0132] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Heavily phosphorus-doped and undoped contact layer 5 (single layer). Example 16

[0133] Similarly, the TOPCon battery in this embodiment adopts the following structure: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Lightly phosphorus-doped and undoped layer + Heavily phosphorus-doped and undoped layer (double contact layer 5).

[0134] Comparative Example 1 The difference between this comparative example and Example 1 is that contact layer 5 is not provided in this comparative example (i.e., a contact structure with no lightly phosphorus-doped and lightly carbon-doped layer + a heavily phosphorus-doped and undoped layer). Therefore, the structure of this TOPCon battery is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer.

[0135] After completing the above structural deposition, a high-temperature crystallization annealing process is directly performed, specifically as follows: The crystallization annealing temperature is 930℃, and the duration is about 30 minutes, which is used to improve the density of the film and the quality of the crystal.

[0136] Subsequently, the RCA standard cleaning process is performed to remove surface impurities and the amorphous oxide layer.

[0137] After cleaning, silicon nitride antireflective films are deposited on the front and back of the battery respectively to improve optical performance, as detailed below: A 70nm thick silicon nitride film is deposited on the front side and used as an anti-reflection film. An 80nm thick silicon nitride film is deposited on the back side and used as a passivation and reflection structure.

[0138] Comparative Example 2 The difference between this comparative example and Example 1 is that a heavily phosphorus-doped and heavily carbon-doped layer was not deposited on the surface of the second tunneling oxide layer 31 in this comparative example, that is, this functional layer was omitted.

[0139] Therefore, the structure of this TOPCon battery is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Contact layer 5 (lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer).

[0140] In this structure, the contact layer 5 is deposited directly after the second tunneling oxide layer 31, without a heavily phosphorus-doped and heavily carbon-doped layer on top of it, thus missing the high carrier concentration gradient and bandgap modulation effect provided by this layer.

[0141] The subsequent processes are the same as in Example 1.

[0142] Comparative Example 3 The difference between this comparative example and Example 2 is that the contact layer 5 (i.e., the contact structure of not depositing a lightly phosphorus-doped and lightly carbon-doped layer + a heavily phosphorus-doped and undoped carbon layer) is not provided in this comparative example.

[0143] Therefore, the structure of this TOPCon cell is: silicon substrate 1 / first tunneling oxide layer 21 / lightly phosphorus-doped and undoped carbon layer / second tunneling oxide layer 31 / heavily phosphorus-doped and heavily doped carbon layer.

[0144] After completing the above-mentioned structural deposition, a high-temperature crystallization annealing treatment is directly performed. The specific process parameters are as follows: the crystallization annealing temperature is 930℃ and the annealing time is about 30 minutes, which is used to improve the crystallization quality of the film and the overall structural stability.

[0145] Subsequently, the RCA cleaning process was used to remove residual impurities and oxide layers from the surface.

[0146] After cleaning, silicon nitride anti-reflection films are deposited on the front and back sides of the battery, respectively: the front silicon nitride film is 70nm thick to improve light incident efficiency; the back silicon nitride film is 80nm thick to have both passivation and reflection functions.

[0147] Since the contact layer 5 is not provided, an effective carrier collection path cannot be formed, resulting in a significant increase in contact resistance. The battery open-circuit voltage (Voc), short-circuit current density (Isc), and fill factor (FF) are all significantly lower than in Example 2, verifying the important role of the contact layer 5 structure in achieving efficient electron extraction and improving the overall battery performance.

[0148] Comparative Example 4 The difference between this comparative example and Example 2 is that a heavily phosphorus-doped and heavily carbon-doped layer was not deposited on the surface of the second tunneling oxide layer 31 in this comparative example, that is, this functional layer was omitted.

[0149] Therefore, the structure of this TOPCon battery is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and undoped carbon layer / Second tunneling oxide layer 31 / Contact layer 5 (lightly phosphorus-doped and lightly doped carbon layer + heavily phosphorus-doped and undoped carbon layer).

[0150] In this structure, the contact layer 5 is deposited directly after the second tunneling oxide layer 31, without a heavily phosphorus-doped or heavily carbon-doped layer, thus missing its key role in enhancing selective carrier transport, optimizing band alignment, and reducing contact resistance.

[0151] The subsequent process flow is the same as in Example 2.

[0152] Comparative Example 5 The difference between this comparative example and Example 9 is that the contact layer 5 is not provided in this comparative example, that is, the contact structure of a lightly phosphorus-doped and lightly carbon-doped layer + a heavily phosphorus-doped and undoped carbon layer is not deposited on the top of the three-tunnel structure.

[0153] Therefore, the structure of this TOPCon battery is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Heavily phosphorus-doped and heavily carbon-doped layer / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer.

[0154] The above structure does not form an effective electron extraction contact interface and lacks the band alignment adjustment and interface carrier selective extraction channel provided by contact layer 5.

[0155] The subsequent crystallization annealing and RCA cleaning are carried out, and silicon nitride films are deposited on the front and back sides respectively. The process flow includes: crystallization annealing: 930℃, 30 minutes; RCA cleaning to remove impurities; deposition of 70nm silicon nitride film on the front side and 80nm silicon nitride film on the back side.

[0156] Comparative Example 6 The difference between this comparative example and Example 9 is that no heavily phosphorus-doped and heavily carbon-doped layer was deposited on the surface of the second tunneling oxide layer 31 in this comparative example.

[0157] Therefore, the structure of this TOPCon battery is as follows: Silicon substrate 1 / First tunneling oxide layer 21 / Lightly phosphorus-doped and lightly carbon-doped layer / Second tunneling oxide layer 31 / Third tunneling oxide layer 41 / Heavily phosphorus-doped and heavily carbon-doped layer / Contact layer 5 (lightly phosphorus-doped and lightly carbon-doped layer + heavily phosphorus-doped and undoped layer).

[0158] That is, the structure omits the first heavily phosphorus-doped and heavily carbon-doped layer between the second tunneling oxide layer 31 and the third tunneling oxide layer 41, and lacks the key intermediate doping adjustment structure.

[0159] The subsequent processes are consistent with those in Example 9, including: high-temperature crystallization annealing (930°C, 30 minutes); RCA cleaning; deposition of 5nm aluminum oxide on the front side to improve passivation effect; deposition of silicon nitride films (70nm / 80nm) on the front and back sides; screen printing and sintering.

[0160] Test case This test aims to compare the performance of TOPCon batteries with different structures, evaluate their overall performance in terms of open-circuit voltage (Voc), contact resistance (Rc), fill factor (FF), and short-circuit current density (Jsc), and verify the actual role of key functional layers in the structural design.

[0161] The test subjects were the TOPCon cells prepared in Examples 1, 2, and 9, and Comparative Examples 1 to 6. The open-circuit voltage (Voc), contact resistance (Rc), fill factor (FF), and short-circuit current density (Jsc) of the sample cells were measured using standard testing procedures. The Sinton test equipment and a standard solar simulator were used for evaluation, and the test conditions were AM1.5 spectrum, 1000 W / m², and 25°C.

[0162] The test data is summarized in the table below: serial number Structure type η (%) Voc (mV) ρc (mΩ·cm²) FF (%) Jsc (mA / cm²) Example 1 Dual tunneling (including lightly phosphorus- and lightly carbon-doped + heavily phosphorus- and heavily carbon-doped) + contact layer (lightly phosphorus- and lightly carbon-doped + heavily phosphorus- and no carbon-doped) 25.8 740 1.5 83.8 15.9 Comparative Example 1 Dual tunneling (including lightly phosphorus- and lightly carbon-doped, + heavily phosphorus- and heavily carbon-doped), no contact layer 25.48 738 4 83.5 15.8 Comparative Example 2 Dual tunneling (including lightly phosphorus-doped and lightly carbon-doped, and no heavy phosphorus-doped and heavy carbon-doped) + contact layer (lightly phosphorus-doped and lightly carbon-doped + heavily phosphorus-doped and no carbon-doped) 25.48 737.9 2.5 83.5 15.81 Example 2 Dual tunneling (including lightly phosphorus-doped and undoped carbon + heavily phosphorus-doped and heavily doped carbon) + contact layer (lightly phosphorus-doped and lightly doped carbon + heavily phosphorus-doped and undoped carbon) 25.82 740 1.5 84 15.88 Comparative Example 3 Dual tunneling (including lightly phosphorus-doped and undoped + heavily phosphorus-doped and heavily doped carbon), without contact layer 25.49 738 3.5 83.55 15.8 Comparative Example 4 Double tunneling (including lightly phosphorus-doped and undoped, and lightly phosphorus-doped and heavily doped), and lightly phosphorus-doped and heavily doped carbon layers. 25.5 737.8 2.2 83.5 15.82 Example 9 Three tunnels (including lightly phosphorus-doped and lightly carbon-doped + heavily phosphorus-doped and heavily carbon-doped + heavily phosphorus-doped and heavily carbon-doped) + contact layer (lightly phosphorus-doped and lightly carbon-doped + heavily phosphorus-doped and no carbon-doped) 25.86 741 1.4 83.9 15.9 Comparative Example 5 Three-tunnel penetration (including lightly phosphorus-doped and lightly carbon-doped + heavily phosphorus-doped and heavily carbon-doped + heavily phosphorus-doped and heavily carbon-doped), without contact layer. 25.68 739 5 83.8 15.85 Comparative Example 6 Three-stage tunnel (including lightly phosphorus- and lightly carbon-doped + heavily phosphorus- and heavily carbon-doped, without an intermediate heavily phosphorus- and heavily carbon-doped layer) + contact layer 25.49 738 7 83.8 15.75 The data in the table shows that: Examples 1, 2 and 9 all employ a complete contact layer 5 structure, exhibiting high Voc (≥740 mV) and low ρc (≤1.5 mΩ·cm²), while also maintaining high levels in terms of FF and Jsc; In comparative examples 1, 3, and 5, the contact layer 5 was not provided, resulting in a significant increase in contact resistance and a noticeable decrease in FF. In Comparative Examples 2, 4, and 6, the key heavily phosphorus-doped and heavily carbon-doped layers were missing. Although the contact layer was retained, the field-effect passivation and bandgap modulation were insufficient, and the electrical performance was significantly weaker than that of the Examples.

[0163] The experimental results verified the key technological value of contact layer 5 and heavily doped layer in optimizing battery performance.

[0164] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0165] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0166] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A TOPCon battery, characterized in that: include: A substrate having a first surface facing the incident light and a second surface facing away from the incident light; The second side of the substrate is provided with two or three tunneling passivation layers, and a contact layer disposed on the tunneling passivation layers. The tunneling passivation layer includes a tunneling oxide layer and a phosphorus-doped layer; the contact layer is a single-layer structure or a double-layer structure, wherein: When it is a single-layer structure, the contact layer is a lightly phosphorus-doped but uncarbon-doped layer or a heavily phosphorus-doped but uncarbon-doped layer; When it is a double-layer structure, the contact layer sequentially includes a lightly phosphorus-doped and lightly carbon-doped layer and a heavily phosphorus-doped and undoped layer, or includes a lightly phosphorus-doped and undoped layer and a heavily phosphorus-doped and undoped layer.

2. The TOPCon battery according to claim 1, characterized in that: When the tunneling passivation layer is a two-layer structure, the outermost phosphorus-doped layer is a heavily phosphorus-doped and heavily carbon-doped layer. When the tunneling passivation layer has a three-layer structure, the two outermost phosphorus-doped layers are both heavily phosphorus-doped and heavily carbon-doped layers.

3. A TOPCon battery according to claim 2, characterized in that: The activation concentration of phosphorus in the heavily phosphorus-doped carbon layer is 1E20~3E20 cm⁻¹. -3 The carbon doping concentration is 1E21~4E21cm. -3 .

4. A TOPCon battery according to claim 3, characterized in that: The phosphorus-doped layer in the first tunneling passivation layer in the direction from the substrate to the contact layer is either a lightly phosphorus-doped, undoped layer or a lightly phosphorus-doped, lightly carbon-doped layer.

5. A TOPCon battery according to claim 1, characterized in that: The activation concentration of phosphorus in the first tunneling passivation layer is 2E20~5E20 cm⁻¹ -3 The carbon doping concentration is 9E20~2E21 cm⁻¹ -3 .

6. A TOPCon battery according to any one of claims 1-5, characterized in that: The activation concentration of phosphorus in the lightly phosphorus-doped, non-carbon-doped layer is 1E20~3E20 cm⁻¹. -3 ; and / or The activation concentration of phosphorus in the lightly phosphorus-doped carbon layer is 1E20~3E20 cm⁻¹. -3 The carbon doping concentration is 1E21~4E21cm. -3 ; and / or The activation concentration of phosphorus in the heavily phosphorus-doped but undoped layer is 1E20~4E20 cm⁻¹. -3 .

7. A method for preparing a TOPCon battery as described in any one of claims 1-6, characterized in that: Includes the following steps: 1) Provide a substrate having a first surface facing the incident light and a second surface facing away from the incident light; 2) Two or three tunneling passivation layers are sequentially formed on the second surface of the substrate, wherein the tunneling passivation layers include a tunneling oxide layer and a phosphorus doped layer; 3) A contact layer is formed on the surface of the tunneling passivation layer, wherein the contact layer is formed in one of the following two ways: When forming a single-layer contact layer, the single-layer contact layer is a lightly phosphorus-doped but uncarbon-doped layer or a heavily phosphorus-doped but uncarbon-doped layer; When a double contact layer is formed, the double contact layer is, in sequence, a lightly phosphorus-doped and lightly carbon-doped layer and a heavily phosphorus-doped and undoped layer, or in sequence, a lightly phosphorus-doped and undoped layer and a heavily phosphorus-doped and undoped layer.

8. The preparation method according to claim 7, characterized in that: The method for forming the phosphorus-doped layer in the first tunneling passivation layer in the direction from the substrate to the contact layer in step 2 includes: A lightly phosphorus-doped, undoped carbon layer, or a lightly phosphorus-doped, lightly carbon-doped layer, is formed on the first tunneling oxide layer.

9. The preparation method according to claim 7, characterized in that: In step 2, when the tunneling passivation layer is a two-layer structure, the outermost phosphorus doped layer is a heavily phosphorus-doped and heavily carbon-doped layer. When the tunneling passivation layer has a three-layer structure, the two outermost phosphorus-doped layers are both heavily phosphorus-doped and carbon-doped layers.

10. A photovoltaic module, characterized in that: This includes the TOPCon battery as described in any one of claims 1-6 or the TOPCon battery prepared by the method described in any one of claims 7-9.

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