Silicon-based heterojunction solar cell, preparation method, electric equipment and application

Abstract

The invention relates to a silicon-based heterojunction solar cell, a preparation method, electric equipment and application, and the silicon-based heterojunction solar cell comprises a silicon substrate, a first passivation layer, an N-type doped layer and a first transparent electrode which are sequentially arranged in a first direction, the first direction is the direction from the silicon substrate to the first transparent electrode in the thickness direction of the silicon substrate; the N-type doped layer comprises a plurality of sub-layers which are sequentially arranged in the first direction: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer and an oxygen-free contact layer. Through the optimal design of the N-type doping layer, the conductivity of the N-type doping layer is not affected, additional carrier recombination is not brought, the overall process is simple, and the prepared solar cell can improve the current density and improve the cell efficiency on the premise of keeping fill factors. The silicon-based heterojunction solar cell can efficiently utilize light energy in photovoltaic application.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the title "Silicon-based Heterojunction Solar Cell, Preparation Method, Electrical Equipment and Application", application number 202311618879.1, filed by the applicant on November 30, 2023. Technical Field

[0002] The present invention relates to the field of photovoltaic technology, and particularly to a silicon-based heterojunction solar cell, a preparation method, electrical equipment and an application. Background Art

[0003] With the development of photovoltaic technology and the continuous increase in market demand, various types of solar cells have been widely studied. Silicon-based heterojunction cells have attracted much attention in the scientific research field and the industry due to their advantages of good weak light response, high efficiency, simple process and high bifaciality. However, the efficiency of mass-produced silicon-based heterojunction cells is still relatively low and cannot meet the market's expectations for them. Summary of the Invention

[0004] Based on this, the objectives of the present application include providing a silicon-based heterojunction solar cell with an N-type doping layer, which has a high fill factor and a high current density, and is conducive to improving the light utilization efficiency; and also providing a preparation method, electrical equipment and an application.

[0005] In a first aspect of the present application, there is provided a silicon-based heterojunction solar cell, including a silicon substrate, a first passivation layer, an N-type doping layer and a first transparent electrode sequentially arranged along a first direction, wherein the first direction is the direction from the silicon substrate to the first transparent electrode in the thickness direction of the silicon substrate;

[0006] The N-type doping layer includes the following multiple sub-layers sequentially arranged along the first direction: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main layer and an oxygen-free contact layer.

[0007] In one embodiment, in the silicon-based heterojunction solar cell, the oxygen-silicon ratio in the oxygen-containing seed layer ≥ 0.6, and the silicon-oxygen ratio in the oxygen-containing main layer ≥ 0.6.

[0008] In one embodiment, in the silicon-based heterojunction solar cell, the energy band of the oxygen-free seed layer is 1.3 eV to 1.4 eV, and the energy band of the oxygen-containing seed layer is 1.6 eV to 2 eV.

[0009] In one embodiment, the silicon-based heterojunction solar cell satisfies one or more of the following conditions:

[0010] Along the first direction, the crystallization rate of each layer in the N-type doping layer increases sequentially;

[0011] The doping activation concentration of P element in the oxygen-containing main body layer is greater than 1×10 17 / cm 3 ;

[0012] The doping activation concentration of P element in the oxygen-free contact layer is greater than 1×10 17 / cm 3 .

[0013] In one embodiment, the silicon-based heterojunction solar cell satisfies one or more of the following conditions:

[0014] The thickness of the oxygen-free seed layer ≤ 0.5 nm;

[0015] The thickness of the oxygen-containing seed layer ≤ 0.5 nm;

[0016] The thickness of the oxygen-containing main body layer is 13 nm to 14 nm;

[0017] The thickness of the oxygen-free contact layer is 1.5 nm to 2.5 nm.

[0018] In one embodiment, in the silicon-based heterojunction solar cell, along the opposite direction of the first direction, a second passivation layer, a P-type doping layer, and a second transparent electrode are sequentially disposed on a side of the silicon substrate away from the first passivation layer.

[0019] In one embodiment, in the silicon-based heterojunction solar cell, the first passivation layer and the second passivation layer are each independently an intrinsic hydrogenated amorphous silicon layer; the silicon substrate is a microcrystalline silicon substrate or a nanocrystalline silicon substrate.

[0020] In a second aspect of the present application, a method for manufacturing a silicon-based heterojunction solar cell is provided, including the following steps:

[0021] Form a first passivation layer, an N-type doping layer, and a first transparent electrode in sequence on one surface of the silicon substrate;

[0022] Among them, forming the N-doped layer on the first passivation layer includes: sequentially forming the following sub-layers on a side of the first passivation layer away from the silicon substrate: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer.

[0023] In one embodiment, the manufacturing method satisfies one or more of the following conditions:

[0024] The reaction gas raw materials H 2 , SiH 4 and PH 3 The molar ratio is 400:1:0.2 to 400:1:0.4, and the pressure of the reaction gas is 2 to 3 mbar;

[0025] The reaction gas raw materials H 2 、SiH 4 、CO 2 and PH 3 have a molar ratio of 400:1:0.4:0.3 to 400:1:0.8:0.6, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0026] In one embodiment, the preparation method satisfies one or more of the following conditions:

[0027] The reaction gas raw materials H 2 、SiH 4 、CO 2 and PH 3 for forming the oxygen-containing main layer are 160:1:0.6:0.4 to 200:1:0.8:0.8, and the pressure of the reaction gas is 2 mbar to 3 mbar;

[0028] The reaction gas raw materials H 2 、SiH 4 and PH 3 for forming the oxygen-free contact layer are 160:1:0.6 to 200:1:0.8, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0029] In the third aspect of the present application, there is provided an electrical device including the silicon-based heterojunction solar cell described in the first aspect or the silicon-based heterojunction solar cell prepared by the preparation method described in the second aspect.

[0030] In the fourth aspect of the present application, there is provided an application of the silicon-based heterojunction solar cell described in the first aspect or the silicon-based heterojunction solar cell prepared by the preparation method described in the second aspect or the electrical device described in the third aspect in photovoltaic power generation.

[0031] In the silicon-based heterojunction solar cell provided in the present application, the N-type doping layer includes an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main layer, and an oxygen-free contact layer stacked in sequence; wherein, the provided oxygen-free seed layer is beneficial to improving the crystallization rate of the N main layer (i.e., the oxygen-containing main layer), the oxygen-containing seed layer can increase the overall band gap of the seed layer and reduce the additional carrier recombination caused by the sharp shrinkage of the band gap due to the high crystallization of the oxygen-free seed layer, the oxygen-containing main layer can improve the conductivity while ensuring the transmittance, and the oxygen-free contact layer can reduce the contact resistance between the silicon thin film layer and the transparent conductive oxide layer. Through the optimized design of the N-type doping layer, the current can be increased while ensuring the FF, realizing the improvement of the battery efficiency.

[0032] The preparation method provided in this application can achieve the lamination of an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer on an oxygen-free seed layer, without affecting the conductivity of the N-type doping layer and without causing additional carrier recombination. The overall process is simple, and the prepared solar cell can increase the current density while maintaining the fill factor.

[0033] The electrical equipment provided in this application has a high utilization rate of light energy, which is beneficial to reducing costs and increasing the battery life.

[0034] The silicon-based heterojunction solar cell provided in this application can increase the current density while maintaining the fill factor, and can efficiently utilize light energy in photovoltaic applications. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0036] Figure 1 It is a schematic diagram of the N-type doping layer of a silicon-based heterojunction solar cell in an implementation manner of this application; among them, the meanings of the marks are as follows: oxygen-free seed (201), oxygen-containing seed layer (202), oxygen-containing main body layer (203), oxygen-free contact layer (204).

[0037] Figure 2 It is a schematic diagram of a silicon-based heterojunction solar cell in an implementation manner of this application; among them, the meanings of the marks are as follows: first transparent electrode (1), N-type doping layer (2), oxygen-free seed (201), oxygen-containing seed layer (202), oxygen-containing main body layer (203), oxygen-free contact layer (204), i-α-Si:H (3), n-c-Si silicon wafer (4), i-α-Si:H (5), P-type doping layer (6), second transparent electrode (7), grid line electrode (8), and grid line electrode (9). Detailed Embodiments

[0038] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0041] The term

[0042] Unless otherwise stated or there is a contradiction, the terms or phrases used herein have the following meanings:

[0043] In the present invention, when it comes to "a plurality of", "a variety of", etc., unless otherwise specified, it means greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0044] In the present invention, "further", "especially", etc. are used for descriptive purposes and represent differences in content, but should not be construed as limiting the protection scope of the present invention.

[0045] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0046] In the present invention, when it comes to a numerical interval (that is, a numerical range), unless otherwise specified, the distribution of the optional numerical values within this numerical interval is regarded as continuous, and includes the two numerical endpoints of this numerical interval (that is, the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When providing multiple numerical ranges to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows a broad inclusion of numerical interval types such as a percentage interval, a ratio interval, a ratio interval, etc.

[0047] In the present invention, the term "room temperature" generally refers to 4°C to 35°C, preferably 20°C ± 5°C. In some embodiments of the present invention, the room temperature refers to 20°C to 30°C.

[0048] In the present invention, unless otherwise specified, the temperature parameter allows both constant temperature treatment and variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuation within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C is allowed.

[0049] In the present invention, for the unit of the data range, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 2~5h means that the units of both the left endpoint "2" and the right endpoint "5" are h (hours).

[0050] With the development of photovoltaic technology and the continuous increase in market demand, various types of solar cells have been widely studied. Silicon-based heterojunction cells have attracted much attention in the scientific research field and the industry due to their advantages of good weak light response, relatively high efficiency, simple process, and high bifaciality. However, the efficiency of mass-produced silicon-based heterojunction cells is still relatively low and cannot meet the market's expectations.

[0051] Compared with traditional solar cell technologies, the silicon-based heterojunction cell (Heterojunction with Intrinsic Thin-layer, abbreviated as "HJT") is a high-efficiency solar cell structure. The HJT cell mainly includes an N-type crystalline silicon substrate and amorphous silicon thin films. The back of the cell includes a transparent conductive oxide film (transparent conductive oxide, abbreviated as "TCO", also can be abbreviated as TCO film), a P-type amorphous silicon thin film, and a hydrogenated amorphous silicon thin film; the front of the cell includes a TCO transparent conductive oxide film, an N-type amorphous silicon thin film, and an intrinsic amorphous silicon film. The introduction of amorphous silicon thin films enables the heterojunction solar cell to combine the advantages of crystalline silicon and thin-film solar cells, has a good surface passivation effect, and also avoids the direct contact between the metal electrode and the silicon material, further reducing the carrier recombination loss, thus being beneficial to the improvement of the cell conversion efficiency. In addition, the HJT cell also has technical advantages such as low process temperature, few preparation processes, and high bifaciality, and has received extensive attention from the R & D and industrial circles.

[0052] Optimization of amorphous silicon is one of the ways to improve the efficiency of HJT cells. With the development of technology, the performance requirements for the N-type doped layer in the single-sided or double-sided microcrystalline cell structure are getting higher and higher. The N-type doped layer should at least have good optical transparency, good carrier transportability, and good contact with the TCO layer. In fact, currently, the industry generally believes that the optimization of the N-type doped layer (close to the light-facing surface) has entered a bottleneck, and the current mainstream research direction focuses on the optimization of the P-type doped layer (close to the backlight surface).

[0053] Through a large amount of creative work, the inventors of the present application provide an N-type doping layer, which can further increase the open-circuit voltage of the battery, thus facilitating the improvement of battery efficiency.

[0054] In a first aspect of the present application, a silicon-based heterojunction solar cell is provided, which includes a silicon substrate, a first passivation layer, an N-type doping layer, and a first transparent electrode sequentially arranged in a first direction, where the first direction is the direction from the silicon substrate to the first transparent electrode in the thickness direction of the silicon substrate;

[0055] The N-type doping layer includes the following multiple sub-layers sequentially arranged in the first direction: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer.

[0056] In the silicon-based heterojunction solar cell provided in the present application, the N-type doping layer includes an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer stacked in sequence. The N-type doping layer provided in the present application is functionally designed according to different functional requirements, and the N layer is divided into multiple sub-layers, namely an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer. Among them, the provided oxygen-free seed layer is beneficial to improving the crystallization rate of the N main body layer (i.e., the oxygen-containing main body layer), the oxygen-containing seed layer can increase the overall band gap of the seed layer and reduce the additional carrier recombination caused by the sharp contraction of the band gap due to the high crystallization of the oxygen-free seed layer. The oxygen-containing main body layer with high oxygen content and high phosphorus doping can improve the conductivity while ensuring the transmittance, and the oxygen-free contact layer with high phosphorus doping can reduce the contact resistance between the silicon thin film layer and the transparent conductive oxide layer. Through the optimized design of the N-type doping layer, the current can be increased while ensuring the FF, realizing the improvement of battery efficiency.

[0057] Figure 1 It is a schematic diagram of the N-type doping layer of a silicon-based heterojunction solar cell in an embodiment of the present application, where 201 is an oxygen-free seed, 202 is an oxygen-containing seed layer, 203 is an oxygen-containing main body layer, and 204 is an oxygen-free contact layer.

[0058] In one embodiment, in the silicon-based heterojunction solar cell, the oxygen-silicon ratio in the oxygen-containing seed layer ≥ 0.6, and further can be 0.6 - 0.8. If the oxygen-silicon ratio in the oxygen-containing seed layer is too low, it may cause a narrow energy band of the seed layer and easily cause carrier recombination. The composition of the oxygen-containing seed layer can be P-doped microcrystalline silicon oxide (P depedμc-SiO x )

[0059] It can be understood that, unless otherwise specified, the oxygen-silicon ratio of the oxygen-containing seed layer in the present application refers to the ratio of oxygen atoms to silicon atoms inside the thin film.

[0060] In one embodiment, in the silicon-based heterojunction solar cell, the silicon-oxygen ratio in the oxygen-containing main body layer is ≥ 0.6, and further can be 0.6 to 0.9. When the oxygen-silicon ratio of the oxygen-containing main body layer is too low, it may cause a decrease in the film transmittance and result in additional optical losses.

[0061] It can be understood that, unless otherwise specified, the silicon-oxygen ratio of the oxygen-containing main body layer in this application refers to the ratio of oxygen atoms to silicon atoms inside the film.

[0062] In one embodiment, in the silicon-based heterojunction solar cell, the energy band of the oxygen-free seed layer is 1.3 eV to 1.4 eV, and can also be selected from any one of the following band gaps or an interval composed of any two of the following band gaps: 1.3 eV, 1.31 eV, 1.32 eV, 1.33 eV, 1.34 eV, 1.35 eV, 1.36 eV, 1.37 eV, 1.38 eV, 1.39 eV, 1.4 eV.

[0063] In one embodiment, in the silicon-based heterojunction solar cell, the energy band of the oxygen-containing seed layer is 1.6 eV to 2 eV, and further can be 1.6 eV to 1.8 eV, and can also be selected from any one of the following band gaps or an interval composed of any two of the following band gaps: 1.3 eV, 1.4 eV, 1.5 eV, 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2 eV.

[0064] In one embodiment, in the silicon-based heterojunction solar cell, the energy band of the oxygen-containing main body layer is 1.6 eV to 1.9 eV, and can also be selected from any one of the following band gaps or an interval composed of any two of the following band gaps: 1.3 eV, 1.4 eV, 1.5 eV, 1.6 eV, 1.7 eV, 1.8 eV, 1.9 eV, 2 eV.

[0065] In one embodiment, in the silicon-based heterojunction solar cell, the energy band of the oxygen-free contact layer is 1.3 eV to 1.5 eV, and can also be selected from any one of the following band gaps or an interval composed of any two of the following band gaps: 1.3 eV, 1.31 eV, 1.32 eV, 1.33 eV, 1.34 eV, 1.35 eV, 1.36 eV, 1.37 eV, 1.38 eV, 1.39 eV, 1.4 eV, 1.41 eV, 1.42 eV, 1.43 eV, 1.44 eV, 1.45 eV, 1.46 eV, 1.47 eV, 1.48 eV, 1.49 eV, 1.5 eV, etc.

[0066] In one embodiment, in the silicon-based heterojunction solar cell, along the first direction, the crystallization rate of each layer in the N-type doped layer increases successively. If the crystallization rate of the N-type doped layer is too high, the recombination degree of electrons and holes in the valence band is relatively high, resulting in additional FF loss; if the crystallization rate of the N-type doped layer is too low, it may be unfavorable for carrier transport, also causing a decrease in the fill factor FF.

[0067] In one embodiment, in the silicon-based heterojunction solar cell, the crystallization rate of the oxygen-free seed layer is 40% - 60%, and it can also be selected from any one crystallization rate or an interval composed of any two crystallization rates: 40%, 45%, 50%, 55%, 60%, etc.

[0068] In one embodiment, in the silicon-based heterojunction solar cell, the crystallization rate of the oxygen-containing seed layer is 30% - 40%, and it can also be selected from any one crystallization rate or an interval composed of any two crystallization rates: 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.

[0069] In one embodiment, in the silicon-based heterojunction solar cell, the crystallization rate of the oxygen-containing main layer is 30% - 45%, and it can also be selected from any one crystallization rate or an interval composed of any two crystallization rates: 30%, 35%, 40%, 45%, etc.

[0070] In one embodiment, in the silicon-based heterojunction solar cell, the crystallization rate of the oxygen-free contact layer is 40% - 60%, and it can also be selected from any one crystallization rate or an interval composed of any two crystallization rates: 40%, 45%, 50%, 55%, 60%, etc.

[0071] In one embodiment, in the silicon-based heterojunction solar cell, the doping activation concentration of P element in the oxygen-containing main layer is greater than or equal to 1×10 17 cm 3 , and further can be 1×10 17 cm 3 ~1.5×10 21 cm 3 , and it can also be selected from any one doping activation concentration or an interval composed of any two doping activation concentrations: 1×10 17 / cm 3 , 5×10 17 / cm 3 , 1×10 18 / cm 3 , 5×10 18 / cm 3 , 1×10 19 / cm 3 , 5×10 19 / cm3 、1 × 10 20 / cm 3 、5 × 10 20 / cm 3 、1 × 10 21 / cm 3 、1.5 × 10 21 / cm 3 etc.

[0072] In one embodiment, in the silicon-based heterojunction solar cell, the doping activation concentration of P element in the oxygen-free contact layer is greater than 1 × 10 17 / cm 3 , and further can be 1 × 10 17 cm 3 ~1.5 × 10 21 cm 3 , and can also be selected from any one of the following doping activation concentrations or an interval composed of any two doping activation concentrations: 1 × 10 17 / cm 3 、5 × 10 17 / cm 3 、1 × 10 18 / cm 3 、5 × 10 18 / cm 3 、1 × 10 19 / cm 3 、5 × 10 19 / cm 3 、1 × 10 20 / cm 3 、5 × 10 20 / cm 3 、1 × 10 21 / cm 3 、1.5 × 10 21 / cm 3 etc.

[0073] In one embodiment, in the silicon-based heterojunction solar cell, the thickness of the oxygen-free seed layer < 0.5 nm, and further can be 0.3 nm~0.5 nm, and can also be selected from any one of the following thicknesses or an interval composed of any two thicknesses: 0.3 nm, 0.35 nm, 0.4 nm, 0.45 nm, 0.5 nm, etc.

[0074] In one embodiment, in the silicon-based heterojunction solar cell, the thickness of the oxygen-containing seed layer < 0.5 nm, and further can be 0.3 nm~0.5 nm, and can also be selected from any one of the following thicknesses or an interval composed of any two thicknesses: 0.3 nm, 0.35 nm, 0.4 nm, 0.45 nm, 0.5 nm, etc.

[0075] In one embodiment, in the silicon-based heterojunction solar cell, the thickness of the oxygen-containing main layer is 13nm to 14nm, and can also be selected from any one or two of the following thicknesses: 13nm, 13.1nm, 13.2nm, 13.3nm, 13.4nm, 13.5nm, 13.6nm, 13.7nm, 13.8nm, 13.9nm and 14nm.

[0076] In one embodiment, in the silicon-based heterojunction solar cell, the thickness of the oxygen-free contact layer is 1.5nm to 2.5nm, and can also be selected from any one or two of the following thicknesses: 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm and 2.5nm.

[0077] In one embodiment, in the silicon-based heterojunction solar cell, a second passivation layer, a P-type doping layer and a second transparent electrode are sequentially arranged on a side of the silicon substrate away from the first passivation layer along a direction opposite to the first direction.

[0078] In one embodiment, in the silicon-based heterojunction solar cell, the first passivation layer and the second passivation layer are each independently an intrinsic hydrogenated amorphous silicon layer; and the silicon substrate is a microcrystalline silicon substrate or a nanocrystalline silicon substrate.

[0079] In one embodiment, reference Figure 2 , the solar cell has the following structure:

[0080] A gate line electrode 8, a first transparent electrode 1, an N-type doped layer 2, the N-type doped layer 2 including an oxygen-free seed 201, an oxygen-containing seed layer 202, an oxygen-containing main layer 203 and an oxygen-free contact layer 204, i-α-Si:H (equivalent to a first passivation layer) 3, a nc-Si silicon wafer (equivalent to a silicon substrate) 4, i-α-Si:H (equivalent to a second passivation layer) 5, a P-type doped layer 6, a second transparent electrode 7 and a gate line electrode 9.

[0081] A second aspect of the present application provides a method for preparing a silicon-based heterojunction solar cell, comprising the following steps:

[0082] A first passivation layer, an N-type doping layer and a first transparent electrode are sequentially formed on a surface of one side of the silicon substrate;

[0083] Wherein, forming the N-doped layer on the first passivation layer includes: forming the following sub-layers in sequence on a side of the first passivation layer away from the silicon substrate: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main layer and an oxygen-free contact layer.

[0084] The second aspect of the present application provides a method for manufacturing a silicon-based heterojunction solar cell, comprising the following steps:

[0085] S200: Form a first passivation layer on the front surface of the silicon substrate; the substrate has two opposite surfaces, which are respectively referred to as the front surface and the back surface;

[0086] S500: Form an N-type doped layer on the side of the first passivation layer formed on the front surface of the substrate away from the substrate;

[0087] Wherein, an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer are sequentially formed on the N-type doped layer in a direction away from the hydrogenated polysilicon layer.

[0088] The manufacturing method provided in the present application can stack an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer on the oxygen-free seed layer, without affecting the conductivity of the N-type doped layer and without introducing additional carrier recombination. The overall process is simple, and the manufactured solar cell can improve the current density while maintaining the fill factor.

[0089] In one embodiment, the method for manufacturing the solar cell comprises the following steps:

[0090] S100: Form a silicon wafer, and the silicon wafer is an N-type single-crystalline silicon wafer; the substrate has two opposite surfaces, which are respectively referred to as the front surface and the back surface;

[0091] S200: Clean and texture the front and back surfaces of the silicon wafer to obtain a substrate with a pyramid-shaped textured surface;

[0092] S300: Form a first passivation layer on the front surface of the substrate;

[0093] S400: Form a second passivation layer on the back surface of the substrate;

[0094] S500: Form an N-type doped layer on the side of the first passivation layer formed on the front surface of the substrate away from the substrate; wherein, an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer are sequentially formed on the N-type doped layer in a direction away from the hydrogenated polysilicon layer;

[0095] S600: Form a p-type doped layer on the side of the second passivation layer formed on the back surface of the substrate away from the substrate;

[0096] S700: Form a TCO film layer on the surfaces of the oxygen-free contact layer of the N-type doped layer and the p-type doped layer respectively;

[0097] S800: Form grid line electrodes on the surfaces of the TCO film layers.

[0098] Understandably, in the step S200, the purpose of the cleaning process is to clean and remove surface organic substances and metal ions, so as to better form the functional layer of the solar cell on the surface of the N-type monocrystalline silicon. In this application, there is no limitation on the method of the cleaning process, which can be the RCA industrial standard wet cleaning process, that is, using SPM (H 2 SO 4 / H 2 O 2 ), HF (DHF), APM (NH 4 OH / H 2 O 2 / H 2 O), HPM (HCl / H 2 O 2 / H 2 O)

[0099] Understandably, in the step S200, the purpose of the texturing process is to form an uneven structure with uniform size on the surface of the silicon wafer. This uneven structure presents a similar pyramid structure in the microscopic morphology, and millions of tetrahedral cones can be formed on the silicon surface per square centimeter. This treatment can enable the incident light to enter the silicon wafer surface from different angles, and increase the absorption of light through the pyramid structure on its surface, thereby realizing the short-circuit current and conversion efficiency of the battery. The texturing process of monocrystalline silicon utilizes the anisotropic etching of silicon. In this application, there is no limitation on the specific method adopted for the texturing process, and it can be realized by using hot alkaline solutions such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and ethylenediamine solution. According to needs, after obtaining a silicon wafer with several tetrahedral cones on its surface by using a hot alkaline solution for texturing, a suitable method such as mechanical grinding can be used to polish the tetrahedral cones that make up the pyramid texture on the silicon wafer surface, so that the sharp square cones on the surface of the tetrahedral cone structure become smooth square cone-like structures; an acidic solution such as HF can also be used to remove the oxide layer on the surface of the pyramid texture.

[0100] Understandably, in the step S200, the cleaning and texturing processes of the silicon wafer can be carried out multiple times according to needs. For example, after using a hot alkaline solution for texturing, the cleaning process can be carried out again according to design and process requirements.

[0101] Understandably, in the steps S300 and S400, the first passivation layer and the second passivation layer can be selected from hydrogenated amorphous silicon or hydrogenated amorphous silicon oxide respectively.

[0102] Understandably, in the step S700, the purposes of forming the TCO film layers on the surfaces of the oxygen-free contact layer of the N-type doped layer and the p-type doped layer include the following aspects: Firstly, by utilizing its light-transmitting property, under sunlight irradiation, light can pass through the TCO thin film and enter the interior of the solar cell, and a p-n junction is formed on its surface; Secondly, by utilizing the electrical conductivity of the TCO film, it allows carriers in the n-type doped layer and the p-type doped layer to pass through and connect with external devices, realizing the directional migration of carriers, thereby completing the conversion of electrical energy. In this application, the composition of the TCO film is not limited, and it can be composed of oxides formed by typical elements such as In, Sb, Zn, and Cd and their composite multi-element oxide materials. In this application, the process methods and equipment for preparing the TCO film are also not limited, and methods such as physical vapor deposition (Physical Vapor Deposition, abbreviated as "PVD"), CVD (Chemical Vapor Deposition, abbreviated as "CVD"), and reactive plasma deposition (Reactive Plasma Deposition, abbreviated as "RPD") and their corresponding equipment can be used to prepare the TCO film.

[0103] Understandably, in the step S800, the function of the grid line electrode is to serve as a bridge between light absorption and charge transfer. The electrode is the current output end of the solar cell, and it can transfer charges from the light absorption layer to the external circuit, completing the conversion and output of electrical energy. Similarly, in this application, the method for preparing the grid line electrode is not limited, and methods such as screen printing, laser transfer technology, and electroplating can be used to prepare the grid line electrode.

[0104] Understandably, in the steps S100 to S800, the silicon wafer of the solar cell or the solar cell precursor including multiple functional layers can be flipped (or turned over) according to process requirements.

[0105] In one embodiment, in the preparation method, the reaction gas raw materials H 2 , SiH 4 and PH 3 have a molar ratio of 400:1:0.2 to 400:1:0.4, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0106] In one embodiment, in the preparation method, the reaction gas raw materials H 2 , SiH 4 , CO 2 and PH 3 have a molar ratio of 400:1:0.4:0.3 to 400:1:0.8:0.6, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0107] In one embodiment, in the preparation method, the reaction gas raw materials H 2 , SiH 4 , CO 2 and PH 3 are in the ratio of 160:1:0.6:0.4 to 200:1:0.8:0.8, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0108] In one embodiment, in the preparation method, the reaction gas raw materials H 2 , SiH 4 and PH 3 are in the ratio of 160:1:0.6 to 200:1:0.8, and the pressure of the reaction gas is 2 mbar to 3 mbar.

[0109] In one embodiment, in the preparation method of the solar cell, the order of steps S400 and S500 can be interchanged.

[0110] In one embodiment, the preparation method of the solar cell (denoted as solar cell (A)) includes the following steps:

[0111] S101: Provide an n-c-Si silicon wafer 4; the n-c-Si silicon wafer has a front side and a back side facing away from each other;

[0112] S201: Clean and damage-remove and texture the front and back sides of the n-c-Si silicon wafer to form a pyramid texture structure with uniform size on the front and back surfaces of the n-c-Si silicon wafer, then remove surface organic substances and metal ions by RCA cleaning, then round the surface pyramids by the Rounding process, and finally remove the oxide layer with an HF solution;

[0113] S301: Sequentially deposit i-α-Si:H3 with a thickness of 9.5 nm on one side (equivalent to the front side) of the silicon wafer by a VHF-PECVD device;

[0114] S401: After turning the wafer over, deposit i-α-Si:H5 with a thickness of 10 nm on the other surface (equivalent to the back side);

[0115] S501: After turning the wafer over, deposit an N-type doped layer 2 with a thickness of 15 nm. The doping activation concentration of P element in the N-type doped layer (oxygen-containing main body layer and oxygen-free contact layer) is 5×10 17 / cm 3; Among them, in the order of preparation, the N-type doped layer 2 includes an oxygen-free seed layer 201, an oxygen-containing seed layer 202, an oxygen-containing main layer 203, and an oxygen-free contact layer 204; among them, the thickness of the oxygen-free seed layer 201 in the N-type doped layer 2 is 0.5 nm, and the preparation condition is H 2 :SiH 4 :PH 3 is 400:1:0.2 to 400:1:0.4, the reaction gas pressure is 3 mbar, the band gap of the obtained oxygen-free seed layer 201 is 1.3 eV, and the crystallization rate is 55%. The oxygen-free seed layer helps to improve the crystallization rate of the oxygen-containing main layer 203; the thickness of the oxygen-containing seed layer 202 in the N-type doped layer 2 is 0.5 nm, and the preparation condition is H 2 :SiH 4 :CO 2 :PH 3 is 400:1:0.8:0.3, the reaction gas pressure is 3 mbar, the oxygen-silicon ratio of the oxygen-containing seed layer of the obtained oxygen-containing seed layer 202 is 0.7, the band gap is 1.7 eV, and the crystallization rate is 40%. It is beneficial to increase the overall band gap of the oxygen-free seed layer and the oxygen-containing seed layer, and reduce the additional carrier recombination caused by the sharp contraction of the band gap caused by the high crystallization of the oxygen-free seed layer 201; the thickness of the oxygen-containing main layer 203 in the N-type doped layer 2 is 13.5 nm, and the preparation condition is H 2 :SiH 4 :CO 2 :PH 3 is 166:1:0.6:0.4, the reaction gas pressure is 3 mbar, the silicon-oxygen ratio of the obtained oxygen-containing main layer 203 is 0.8, the band gap is 1.9 eV, and the crystallization rate is 43%. The oxygen-containing main layer (also called the N main layer) obtained by the method of high oxygen content and high phosphorus doping can improve the conductivity while ensuring the transmittance; the thickness of the oxygen-free contact layer 204 in the N-type doped layer 2 is 3 nm, and the preparation condition is H 2 :SiH 4 :PH 3 is 166:1:0.6, the reaction gas pressure is 3 mbar, the band gap of the obtained oxygen-free contact layer 204 is 1.4 eV, and the crystallization rate is 55%. The oxygen-free contact layer obtained by the method of oxygen-free high phosphorus doping can reduce the contact resistance between the silicon thin film layer and the transparent conductive oxide (TCO) layer, thereby improving the FF of the battery;

[0116] S601: Flip it over again to prepare the P-type doped layer 6 with a thickness of 20 nm; the silicon-based thin film preparation stage is completed;

[0117] S701: Use PVD equipment to prepare TCO1 and TCO7 on the front and back of the silicon wafer, with a thickness of 90 nm each;

[0118] S801: Prepare grid line electrodes 8 and 9 on the front and back surfaces respectively by screen printing method. Among them, the density of the grid line electrode 9 on the P side is greater than that of the grid line electrode 8 on the N side; subsequently, curing and / or annealing treatment of the grid lines is carried out.

[0119] It can be understood that the P side is the side where the dopant in the doped layer is element B, and the N side is the side where the dopant in the doped layer is element P; the N side is the relative front surface, i.e., the light incident surface, and the P side is the relative back surface.

[0120] In one embodiment, the preparation method of the solar cell (denoted as solar cell (B)) is basically the same as the preparation method of the aforementioned solar cell (A), except that in step S501, the preparation raw materials H 2 :SiH 4 :CO 2 :PH 3 is 400:1:1:0.3.

[0121] In one embodiment, the preparation method of the solar cell (denoted as solar cell (C)) is basically the same as the preparation method of the aforementioned solar cell (A), except that in step S501, the preparation raw materials H 2 :SiH 4 :CO 2 :PH 3 is 400:1:0.6:0.3.

[0122] In one embodiment, the preparation method of the solar cell (denoted as solar cell (D)) is basically the same as the preparation method of the aforementioned solar cell (A), except that in step S501, the prepared N-type doped layer 2 includes an oxygen-free seed layer 201, an oxygen-containing main body layer 203, and an oxygen-free contact layer 204, and does not include an oxygen-containing seed layer 202.

[0123] The spectral response test of the solar cell is carried out according to GB 11009-1989, the single crystal cell test is carried out according to GB 12632-1990, and the photovoltaic current-voltage characteristic test of the solar cell is carried out according to GBT 6495.1-1996. The specific conditions are 25 °C, AM1.5G spectrum, 1000 W / cm 2 Light intensity polarity test. The measured performance is shown in Table 1. It should be noted that the performance of the solar cells in Table 1 are all relative values.

[0124] Table 1 Performance comparison of solar cells (A) to (D)

[0125]

[0126] The inventors of the present application also found that if the crystallization rates of the oxygen-free seed layer, oxygen-containing seed layer, oxygen-containing main body layer, and oxygen-free contact layer of the N-type doped layer sequentially arranged in the first direction are not set to increase sequentially, or the crystallization rate of the seed layer is low, it has no positive effect on improving the crystallization rate of the subsequent oxygen-containing main body layer; if the crystallization rate of the oxygen-containing main body layer is too high, it will cause serious parasitic absorption and seriously affect the optical performance.

[0127] In the third aspect of the present application, an electrical device is provided, including the solar cell described in the first aspect or the solar cell prepared by the preparation method described in the second aspect.

[0128] It can be understood that the electrical device can be an electric transportation device (such as ships, spacecrafts, electric vehicles, and battery cars, etc.), a lighting device (lamps and auxiliary lighting components, etc.), a photovoltaic power generation device, and other devices that need to provide electrical energy.

[0129] The electrical device provided in the present application has a high utilization rate of light energy, which is beneficial to reducing costs and increasing the battery life.

[0130] In the fourth aspect of the present application, an application of the solar cell described in the first aspect or the solar cell prepared by the preparation method described in the second aspect or the electrical device described in the third aspect in photovoltaic power generation is provided.

[0131] The silicon-based heterojunction solar cell provided in the present application can increase the current density while maintaining the fill factor (FF), and can efficiently utilize light energy in photovoltaic applications.

[0132] To make the present invention easier to understand and implement, the following also provides relatively easy-to-implement, more specific and detailed examples and comparative examples for reference.

[0133] The following will further illustrate the concept, specific examples, and technical effects of the present invention with reference to the accompanying drawings to fully understand the present invention. The purpose of providing these descriptions is only to help explain the present invention and should not be used to limit the scope of the claims of the present invention.

[0134] Unless otherwise specified, the raw materials used in the following experiments can be conventionally purchased from the market.

[0135] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as within the scope described in this specification.

[0136] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims, and the specification and the drawings can be used to explain the content of the claims.

Claims

1. A silicon-based heterojunction solar cell, It is characterized in that It comprises a silicon substrate, a first passivation layer, an N-type doping layer and a first transparent electrode arranged in sequence along a first direction, wherein the first direction is a direction from the silicon substrate to the first transparent electrode in the thickness direction of the silicon substrate; The N-type doped layer includes the following multiple sub-layers arranged in sequence along the first direction: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main layer and an oxygen-free contact layer; The energy band of the oxygen-free seed layer is 1.3eV to 1.4eV; the crystallization rate of the oxygen-free seed layer is 40% to 60%; The oxygen-silicon ratio of the oxygen-containing seed layer is ≥0.6; the crystallization rate of the oxygen-containing seed layer is 30% to 40%; The silicon-oxygen ratio in the oxygen-containing main body layer is ≥0.6, and the doping activation concentration of P element in the oxygen-containing main body layer is greater than 1×10 17 / cm 3 ; the crystallization rate of the oxygen-containing main body layer is 30% - 45%; The doping activation concentration of P element in the anaerobic contact layer is greater than 1×10 17 / cm 3 ; The crystallization rate of the anaerobic contact layer is 40% - 60%.

2. The silicon-based heterojunction solar cell according to claim 1, It is characterized in that One or more of the following conditions are met: The crystallization rate of the oxygen-free seed layer is 50% to 55%; The crystallization rate of the oxygen-containing seed layer is 35% to 40%; The crystallization rate of the oxygen-containing main layer is 40% to 45%; The crystallization rate of the oxygen-free contact layer is 50% to 55%.

3. The silicon-based heterojunction solar cell according to claim 1, It is characterized in that The energy band of the oxygen-free contact layer is 1.3 eV to 1.5 eV.

4. The silicon-based heterojunction solar cell according to claim 1, It is characterized in that The energy band of the oxygen-containing seed layer is 1.6 eV to 2 eV.

5. The silicon-based heterojunction solar cell according to claim 1, It is characterized in that Meet one or more of the following conditions: the doping activation concentration of P element in the oxygen-containing main body layer is 1×10 17 cm 3 ~1.5×10 21 cm 3 ; The doping activation concentration of P element in the anaerobic contact layer is 1×10 17 cm 3 ~1.5×10 21 cm 3 .

6. The silicon-based heterojunction solar cell according to claim 1, It is characterized in that One or more of the following conditions are met: The thickness of the oxygen-free seed layer is ≤0.5 nm; The thickness of the oxygen-containing seed layer is ≤0.5 nm; The thickness of the oxygen-containing main layer is 13nm to 14nm; The thickness of the oxygen-free contact layer is 1.5 nm to 2.5 nm.

7. The silicon-based heterojunction solar cell according to claim 6, It is characterized in that One or more of the following conditions are met: The thickness of the oxygen-free seed layer is 0.3nm~0.5nm; The thickness of the oxygen-containing seed layer is 0.3 nm to 0.5 nm.

8. The silicon-based heterojunction solar cell according to any one of claims 1 to 7, It is characterized in that Along the direction opposite to the first direction, a second passivation layer, a P-type doping layer and a second transparent electrode are sequentially arranged on a side of the silicon substrate away from the first passivation layer.

9. The silicon-based heterojunction solar cell according to claim 8, It is characterized in that The first passivation layer and the second passivation layer are each independently an intrinsic hydrogenated amorphous silicon layer; and the silicon substrate is a microcrystalline silicon substrate or a nanocrystalline silicon substrate.

10. A method for preparing a silicon-based heterojunction solar cell, It is characterized in that The following steps are involved: A first passivation layer, an N-type doping layer and a first transparent electrode are sequentially formed on a surface of one side of the silicon substrate; Among them, forming the N-type doping layer on the first passivation layer includes: sequentially forming the following sub-layers on the side of the first passivation layer away from the silicon substrate: an oxygen-free seed layer, an oxygen-containing seed layer, an oxygen-containing main body layer, and an oxygen-free contact layer; Among them, the energy band of the oxygen-free seed layer is 1.3 eV to 1.4 eV; the crystallization rate of the oxygen-free seed layer is 40% to 60%; The oxygen-silicon ratio in the oxygen-containing seed layer is ≥0.6; the crystallization rate of the oxygen-containing seed layer is 30% to 40%; The silicon-oxygen ratio in the oxygen-containing main body layer ≥ 0.6; the doping activation concentration of P element in the oxygen-containing main body layer is greater than 1×10 17 / cm 3 ; the reaction gas raw materials H 2 、SiH 4 、CO 2 and PH 3 are 160:1:0.6:0.4 to 200:1:0.8:0.8, the pressure of the reaction gas is 2 mbar to 3 mbar; the crystallization rate of the oxygen-containing main body layer is 30% to 45%; The doping activation concentration of P element in the anaerobic contact layer is greater than 1×10 17 / cm 3 ; the reaction gas raw materials H 2 , SiH 4 and PH 3 for the anaerobic contact layer are 160:1:0.6 to 200:1:0.8, the pressure of the reaction gas is 2 mbar to 3 mbar; the crystallization rate of the anaerobic contact layer is 40% to 60%.

11. According to the preparation method described in claim 10, It is characterized in that One or more of the following conditions are satisfied: The reaction gas raw material H for forming the anaerobic seed layer 2 , SiH 4 and PH 3 have a molar ratio of 400:1:0.2 to 400:1:0.4, and the pressure of the reaction gas is 2 mbar to 3 mbar; The reaction gas raw materials H for forming the oxygen-containing seed layer 2 , SiH 4 , CO 2 and PH 3 have a molar ratio of 400:1:0.4:0.3 to 400:1:0.8:0.6, and the pressure of the reaction gas is 2 mbar to 3 mbar.

12. An electrical device, It is characterized in that It includes the silicon-based heterojunction solar cell described in any one of claims 1 to 9 or the silicon-based heterojunction solar cell prepared by the preparation method described in claim 10 or 11.

13. Application of the silicon-based heterojunction solar cell described in any one of claims 1 to 9 or the silicon-based heterojunction solar cell prepared by the preparation method described in claim 10 or 11 or the electrical device described in claim 12 in photovoltaic power generation.

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