Tunneling oxide layer passivation contact solar cell, preparation method, electric equipment and application

Abstract

The invention relates to a tunneling oxide layer passivation contact solar cell, a preparation method, electric equipment and application. The tunneling oxide layer passivation contact solar cell comprises a silicon substrate, and a tunneling layer, an n-type polycrystalline silicon layer, a conductive layer and a metal electrode which are sequentially stacked on the surface of one side of the silicon substrate, the conductive layer comprises a TiN crystal phase, a TiO2 crystal phase and a titanium oxynitride crystal phase. Compared with a non-conductive barrier layer such as SiN: H, the conductive layer film with a TiN crystal phase and other crystal phases such as TiO2 and titanium oxynitride can improve the current collection effect of an electrode and reduce the contact resistivity, thereby improving the fill factor, the current density and the energy conversion efficiency of the solar cell. The tunneling oxide layer passivation contact solar cell prepared by the preparation method provided by the invention has relatively high fill factor, current density and energy conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly to a tunneling oxide passivated contact solar cell, a preparation method, an electrical equipment and an application thereof. Background Art

[0002] The tunneling oxide passivated contact solar cell is one of the solar cell types with relatively high energy conversion efficiency and has been widely studied in the industry. In traditional technologies, an ohmic contact is formed between the electrode and the passivation layer, and setting a non-conductive barrier layer between the electrode and the passivation layer is likely to cause problems such as poor conductivity and energy level mismatch, making it difficult to improve the efficiency of the solar cell well. Summary of the Invention

[0003] Based on this, the objectives of the present application include providing a tunneling oxide passivated contact solar cell, which includes a conductive layer of TiN crystal phase, TiO 2 crystal phase and titanium oxynitride crystal phase, so as to improve the back electrode current collection effect and interface contact of the TOPCon cell; and also providing a preparation method, an electrical equipment and an application thereof.

[0004] In the first aspect of the present application, a tunneling oxide passivated contact solar cell is provided, which includes a silicon substrate, and a tunneling layer, an n-type polysilicon layer, a conductive layer and a metal electrode that are sequentially stacked on one side surface of the silicon substrate;

[0005] The conductive layer includes TiN crystal phase, TiO 2 crystal phase and titanium oxynitride crystal phase.

[0006] In one embodiment, in the tunneling oxide passivated contact solar cell, the metal electrode is selected from at least one of Ag and Al.

[0007] In one embodiment, in the tunneling oxide passivated contact solar cell, the metal electrode is an Ag electrode.

[0008] In one embodiment, in the tunneling oxide passivated contact solar cell, in the conductive layer, the atomic number ratio of the TiN crystal phase is 20% - 50%, and the atomic number ratio of the TiO 2 crystal phase ≤ 40%, and the atomic number ratio of the titanium oxynitride ≤ 45%.

[0009] In one embodiment, in the conductive layer, the atomic number ratio of the TiN crystal phase is 30% - 50%, the atomic number ratio of the TiO 2 crystal phase is 20% - 40%, and the atomic number ratio of the titanium oxynitride crystal phase is 20% - 40%.

[0010] In one embodiment, in the tunneling oxide passivated contact solar cell, in the conductive layer, at least a part of the TiN crystal phase is face-centered cubic and has a (111) crystal plane.

[0011] In one embodiment, in the tunneling oxide passivated contact solar cell, the atomic number percentage of the TiN crystal phase with a (111) crystal plane in all the TiN crystal phases is 10% - 90%.

[0012] In one embodiment, in the tunneling oxide passivated contact solar cell, the atomic number percentage of the TiN crystal phase with a (111) crystal plane in all the TiN crystal phases is 30% - 70%.

[0013] In one embodiment, in the tunneling oxide passivated contact solar cell, in the conductive layer, the TiO 2 crystal phase of at least a part is anatase tetragonal system or brookite orthorhombic system.

[0014] In one embodiment, the tunneling oxide passivated contact solar cell satisfies one or more of the following characteristics:

[0015] (1) The conductivity of the conductive layer is 0.5 S / cm - 7600 S / cm;

[0016] (2) The work function of the conductive layer is 4.0 eV - 5.4 eV;

[0017] (3) The carrier concentration of the conductive layer is 1×10 21 cm 3 - 9×10 21 cm 3 ;

[0018] (4) The mobility of the conductive layer is 2 cm 2 V -1 s -1 - 10 cm 2 V -1 s -1 .

[0019] In one embodiment, it satisfies one or more of the following characteristics:

[0020] (1) The conductivity of the conductive layer is 3000 S / cm - 6000 S / cm;

[0021] (2) The work function of the conductive layer is 4.2 eV - 4.3 eV;

[0022] (3) The carrier concentration of the conductive layer is 6×10 21 cm 3~8×10 21 cm 3 ;

[0023] (4) The mobility of the conductive layer is 4 cm 2 V -1 s -1 ~6 cm 2 V -1 s -1 。

[0024] In one embodiment, in the tunneling oxide passivated contact solar cell, the thickness of the conductive layer is 1 nm to 10 nm.

[0025] In one embodiment, in the tunneling oxide passivated contact solar cell, the thickness of the conductive layer is 1 nm to 5 nm.

[0026] In a second aspect of the present application, there is provided a method for manufacturing a tunneling oxide passivated contact solar cell, comprising the following steps:

[0027] Providing a substrate for deposition; wherein, the substrate for deposition comprises a silicon substrate, a tunneling layer and an n-type polysilicon layer stacked in sequence;

[0028] Forming a conductive layer and a metal electrode in sequence on a surface of the n-type polysilicon layer facing away from the tunneling layer, to obtain a tunneling oxide passivated contact solar cell;

[0029] Wherein, the conductive layer comprises a TiN crystal phase, a TiO 2 crystal phase and a titanium oxynitride crystal phase.

[0030] In one embodiment, in the manufacturing method, the conductive layer is formed on a surface of the n-type polysilicon layer facing away from the tunneling layer by a method comprising the following steps:

[0031] In a gas atmosphere of argon and nitrogen, using a titanium target, performing DC magnetron sputtering on a surface of the n-type polysilicon layer facing away from the tunneling layer;

[0032] Forming the conductive layer on a surface of the n-type polysilicon layer facing away from the tunneling layer by physical vapor deposition;

[0033] Wherein, the partial pressure ratio of nitrogen to argon is (0.1 to 0.6):1, and the power of the DC magnetron sputtering is 100 W to 300 W.

[0034] In a third aspect of the present application, there is provided an electrical device, comprising the tunneling oxide passivated contact solar cell described in the first aspect or the tunneling oxide passivated contact solar cell manufactured by the manufacturing method described in the second aspect.

[0035] In the fourth aspect of the present application, there is provided an application of the tunneling oxide passivated contact solar cell described in the first aspect, or the tunneling oxide passivated contact 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.

[0036] The tunneling oxide passivated contact solar cell provided in the present application includes a silicon substrate, and a tunneling layer, an n-type polysilicon layer, a conductive layer, and a metal electrode that are sequentially stacked on the first surface of the silicon substrate; the conductive layer includes a TiN crystal phase, TiO 2 crystal phase, and titanium oxynitride crystal phase; the provided conductive layer uses a conductive layer thin film having a TiN crystal phase and TiO 2 , and other crystal phases such as titanium oxynitride, compared with a non-conductive barrier layer such as SiN:H, can improve the current collection effect of the electrode, reduce the contact resistivity, thereby improving the fill factor, current density, and energy conversion efficiency of the solar cell. The tunneling oxide passivated contact solar cell prepared by the preparation method provided in the present application has a high fill factor, current density, and energy conversion efficiency. 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. The tunneling oxide passivated contact solar cell provided in the present application can efficiently utilize light energy in photovoltaic applications. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application and more completely understand the present application and its beneficial effects, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the drawings below are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings. It should also be noted that the drawings are all drawn in a simplified form and are only used to conveniently and clearly assist in explaining the present invention. The various dimensions of each component shown in the drawings are arbitrarily shown, which may be accurate or may not be drawn to actual scale. For example, in order to make the illustration clearer, the dimensions of some components in the drawings are appropriately exaggerated. Unless otherwise specified, the components in the drawings are not drawn to scale. The present invention does not limit each dimension of each component.

[0038] Figure 1 This is the back structure of the tunneling oxide passivated contact solar cell in an embodiment of the present application, where the meanings of the reference numerals are as follows: silicon substrate 1, tunneling layer 2, n-type polysilicon layer 3, conductive layer 4, and metal electrode 5;

[0039] Figure 2This is the structure of a tunneling oxide passivated contact solar cell in an embodiment of the present application. Among them, the meanings of the reference numerals are as follows: silicon substrate 1, tunneling layer 2, n-type polysilicon layer 3, conductive layer 4, metal electrode 5, P-type monocrystalline silicon layer 6, alumina layer 7, SiN:H layer 8, and second electrode 9;

[0040] Figure 3 This is the structure of a tunneling oxide passivated contact solar cell in an embodiment of the present application. Among them, the meanings of the reference numerals are as follows: silicon substrate 11, tunneling layer 21, first passivation layer 31, conductive layer 41, first electrode 51, P-type monocrystalline silicon layer 61, alumina layer 71, SiN:H layer 81, and second electrode 91;

[0041] Figure 4 is Figure 3 The energy band matching diagram of the first passivation layer, conductive layer and first electrode on the back of the tunneling oxide passivated contact solar cell shown in the figure, where silicon substrate 11, tunneling layer 21, first passivation layer 31, conductive layer 41, first electrode 51, electron 101, and hole 102;

[0042] Figure 5 This is the structure of a tunneling oxide passivated contact solar cell in the traditional technology. Among them, the meanings of the reference numerals are as follows: silicon substrate 12, tunneling layer 22, first passivation layer 32, SiN:H layer 42, first electrode 52, P-type monocrystalline silicon layer 62, alumina layer 72, SiN:H layer 82, and second electrode 92;

[0043] Figure 6 is Figure 5 The energy band matching diagram of the first passivation layer and first electrode on the back of the tunneling oxide passivated contact solar cell in the traditional technology shown in the figure. Among them, the meanings of the reference numerals are as follows: silicon substrate 12, tunneling layer 22, first passivation layer 32, first electrode 52, electron 101, and hole 102;

[0044] Figure 7 This is the preparation method of a tunneling oxide passivated contact solar cell in an embodiment of the present application;

[0045] Figure 8 This is the preparation method of a tunneling oxide passivated contact solar cell in another embodiment of the present application. Detailed implementation manners

[0046] For the convenience of understanding 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 content of the present invention more thorough and comprehensive.

[0047] 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, but the protection scope of the present invention is not limited to the following embodiments.

[0048] 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.

[0049] The term

[0050] Unless otherwise stated or there is a contradiction, the terms or phrases used herein have the following meanings:

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 refers to an integer 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 for a broad inclusion of numerical interval types such as a percentage interval, a ratio interval, a ratio interval, etc.

[0055] 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. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0056] 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, 3000~6000 S / cm means that the units of the left endpoint "3000" and the right endpoint "6000" are both S / cm.

[0057] To address issues such as the global energy shortage and the increasing depletion of traditional energy sources (fossil, coal, oil, etc.), it has become a consensus to vigorously develop renewable energy. Solar energy has become one of the fastest-growing renewable energy sources due to its significant advantages such as cleanliness, safety, and rich resources, and photovoltaic power generation is one of its most important utilization methods. After decades of development, photovoltaic power generation technology has also made great progress. The tunnel oxide passivated contact solar cell is one of the solar cell types with relatively high energy conversion efficiency and has been widely studied in the industry. Currently, the highest efficiency of the tunnel oxide passivated contact (TOPCon) solar cell has reached 26.81%, and its mass production efficiency has also reached over 24.5%. In traditional technologies, an ohmic contact is formed between the electrode and the passivation layer, and setting a non-conductive barrier layer between the electrode and the passivation layer easily causes problems such as poor conductivity and energy level mismatch, making it difficult to improve the efficiency of the solar cell well. In traditional technologies, the back of the TOPCon solar cell is designed to use SiN to cover the passivation layer. Since the SiN disposed on the back of the TOPCon cell is in direct contact with the silver electrode and is non-conductive, in order to achieve the collection of current by the back electrode, it is necessary to provide contact between the electrode and the N-type polysilicon (n+poly-Si) layer, generally by designing the electrode to pass through the SiN layer and contact the n+poly-Si layer; although this method of passing the electrode through the SiN layer and contacting the n+poly-Si layer can partially solve the conductivity problem, the ohmic contact formed directly between the n+poly-Si and the Ag electrode causes the energy band to bend upward, resulting in a relatively high electron transport barrier and contact resistivity.

[0058] Based on this, the object of the present application includes providing a tunnel oxide passivated contact solar cell, by inserting a conductive layer between the back electrode of the solar cell, such as an Ag electrode, and the n+poly-Si layer, which includes a TiN crystal phase, a TiO 2 crystal phase, and a titanium oxynitride crystal phase, so as to improve the back electrode current collection effect and interface contact of the TOPCon cell; and also providing a preparation method, an electrical equipment, and an application.

[0059] In the first aspect of the present application, a tunneling oxide passivated contact solar cell is provided, which includes a silicon substrate and a tunneling layer, an n-type polysilicon layer, a conductive layer, and a metal electrode that are sequentially stacked on one surface of the silicon substrate.

[0060] The conductive layer includes a TiN crystal phase, a TiO 2 crystal phase, and a titanium oxynitride crystal phase.

[0061] The tunneling oxide passivated contact solar cell provided in the present application includes a silicon substrate and a tunneling layer, an n-type polysilicon layer, a conductive layer, and a metal electrode that are sequentially stacked on the first surface of the silicon substrate; the conductive layer includes a TiN crystal phase, a TiO 2 crystal phase, and a titanium oxynitride crystal phase; the provided conductive layer uses a conductive layer thin film having a TiN crystal phase, a TiO 2 , a titanium oxynitride and other crystal phases, compared with a non-conductive barrier layer such as SiN:H, can improve the current collection effect of the electrode, reduce the contact resistivity, thereby improving the fill factor, current density, and energy conversion efficiency of the solar cell. It has been experimentally verified that the improvement of the solar cell efficiency is mainly due to the improvement of the fill factor and current density in the electrical performance parameters, and the reduction of the contact resistance and the excellent conductivity of the conductive layer are very direct for the improvement of the fill factor and current density.

[0062] It can be understood that the "layer" structure referred to in the present application, along the cross-section perpendicular to the interface formed by the layer and the adjacent layer, the overall outer contour of the cross-section of the layer (which can also be understood as the projection obtained by the layer in the direction perpendicular to the interface formed by the layer and the adjacent layer) is in the shape of a cuboid; the outer contour of the cross-section or the projection of the layer can be a continuous straight line, and the outer contour can also have a convex or concave shape, and the cuboid-shaped outer contour can also be composed of multiple cross-sections with outer contours (these cross-sections are adjacent or in contact with each other).

[0063] In one embodiment, the tunneling oxide passivated contact solar cell has Figure 1 the back structure shown in

[0064] In one embodiment, the tunneling oxide passivated contact solar cell has Figure 2The structure shown in the figure includes a silicon substrate 1, a tunneling layer 2, an n-type polysilicon layer 3 (also denoted as the first passivation layer), a conductive layer 4, and a metal electrode 5 (also denoted as the first electrode) that are sequentially stacked on the first surface of the silicon substrate. It also includes a P-type single-crystalline silicon layer 6, an alumina layer 7, a SiN:H layer 8, and a second electrode 9 that are sequentially stacked on the second surface of the silicon substrate.

[0065] In one embodiment, in the tunneling oxide passivated contact solar cell, the metal electrode is selected from at least one of Ag and Al. Specifically, in the tunneling oxide passivated contact solar cell, the metal electrode is an Ag electrode.

[0066] In one embodiment, in the tunneling oxide passivated contact solar cell, in the conductive layer, the atomic proportion of the TiN crystal phase is 20% - 50%, TiO 2 The atomic proportion of the crystal phase ≤ 40%, and the atomic proportion of the titanium oxynitride crystal phase ≤ 45%. All other crystal phases except TiN (including TiO 2 Crystal phase, titanium oxynitride crystal phase, etc.) can be called miscellaneous phases. Such miscellaneous phases are difficult to completely remove during the actual annealing process, but the proportion they occupy in the conductive layer can be adjusted by adjusting the process window. TiO 2 The crystal phase and the titanium oxynitride crystal phase have a certain inhibitory effect on the carrier transport. A too high concentration of N element in the conductive layer will increase the film defects and seriously affect the film formation quality, while the existence of an appropriate amount of miscellaneous phases can control the excessive enrichment of N element in the conductive layer. Controlling the relative content of the TiN crystal phase and other crystal phases in the conductive layer further improves the current collection effect of the back silver electrode, reduces the contact resistivity, and thus improves the fill factor, current density, and energy conversion efficiency of the solar cell.

[0067] In one embodiment, in the tunneling oxide passivated contact solar cell, the atomic proportion of the TiN crystal phase in the conductive layer is 20% - 50%, further it can be 30% - 50%, and even further it can be 40% - 50%. It can also be selected from any one of the following proportions or an interval composed of any two of the proportions: 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. For example, the atomic proportion of the TiN crystal phase in the conductive layer is 40%.

[0068] In one embodiment, in the tunneling oxide passivated contact solar cell, the atomic proportion of the TiO 2 Crystal phase in the conductive layer ≤ 40%, further it can be 20% - 40%, and even further it can be 20% - 30%. It can also be selected from any one of the following proportions or an interval composed of any two of the proportions: 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0069] The titanium oxynitride crystal phase is also known as TiO x N y crystal phase, where x ≤ 2, y ≤ 2 and x + y = 2. Among them, the closer the y value is to 2, the better the conductivity of the material, which is more conducive to the collection of current.

[0070] In one embodiment, in the tunneling oxide layer passivated contact solar cell, in the conductive layer, the atomic number ratio of TiO x N y crystal phase is ≤ 45%, further it can be 20% - 40%, still further it can be 20% - 30%, and it can also be selected from any one of the following ratios or the intervals composed of any two of the ratios: 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc.

[0071] In some embodiments, in the conductive layer, the atomic number ratio of the TiN crystal phase is 30% - 50%, and the atomic number ratio of the TiO 2 crystal phase is 20% - 40%, and the atomic number ratio of the titanium oxynitride crystal phase is 20% - 40%. Further, in the conductive layer, the atomic number ratio of the TiN crystal phase is 40% - 50%, and the atomic number ratio of the TiO 2 crystal phase is 20% - 30%, and the atomic number ratio of the titanium oxynitride crystal phase is 20% - 30%.

[0072] In one embodiment, in the tunneling oxide layer passivated contact solar cell, in the conductive layer, the total atomic number percentage of the TiN crystal phase, TiO 2 crystal phase and the titanium oxynitride crystal phase is 100%.

[0073] In one embodiment, in the tunneling oxide layer passivated contact solar cell, in the conductive layer, at least a part of the TiN crystal phase is face-centered cubic crystal system and has a (111) crystal plane.

[0074] In one embodiment, in the tunneling oxide layer passivated contact solar cell, in the conductive layer, the percentage of the TiN crystal phase with a (111) crystal plane in the total atomic number of all TiN crystal phases is 10% - 90%. For example, the percentage of the TiN crystal phase with a (111) crystal plane in the total atomic number of all TiN crystal phases can be but not limited to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or the ranges composed of any two of these values. Optionally, the percentage of the TiN crystal phase with a (111) crystal plane in the total atomic number of all TiN crystal phases is 10% - 70%, 30% - 70% or 30% - 90%, etc.

[0075] In one embodiment, in the tunneling oxide layer passivated contact solar cell, in the conductive layer, TiO 2At least a part of the crystal phase is in the anatase tetragonal system or the brookite orthorhombic system.

[0076] In one embodiment, in the tunneling oxide layer passivated contact solar cell, the conductivity of the conductive layer is 0.5 S / cm to 7600 S / cm, further it can be 3000 S / cm to 6000 S / cm, and it can also be selected from any one of the following conductivities or the intervals formed by any two of the following conductivities: 0.5 S / cm, 100 S / cm, 1000 S / cm, 2000 S / cm, 3000 S / cm, 4000 S / cm, 5000 S / cm, 6000 S / cm, 7000 S / cm, 7600 S / cm, etc.

[0077] In one embodiment, in the tunneling oxide layer passivated contact solar cell, the work function of the conductive layer is 4.0 eV to 5.4 eV, further it can be 4.2 eV to 4.3 eV, and it can also be selected from any one of the following work functions or the intervals formed by any two of the following work functions: 4 eV, 4.1 eV, 4.2 eV, 4.3 eV, 4.4 eV, 4.5 eV, 4.6 eV, 4.7 eV, 4.8 eV, 4.9 eV, 5 eV, 5.2 eV, 5.4 eV, etc.

[0078] In one embodiment, in the tunneling oxide layer passivated contact solar cell, the carrier concentration of the conductive layer is 1×10 21 cm 3 ~9×10 21 cm 3 Further it can be 6×10 21 cm 3 ~8×10 21 cm 3 It can also be selected from any one of the following carrier concentrations or the intervals formed by any two of the following carrier concentrations: 1×10 21 cm 3 、2×10 21 cm 3 、4×10 21 cm 3 、6×10 21 cm 3 、7×10 21 cm 3 、8×10 21 cm 3 、9×10 21 cm 3 etc.

[0079] In one embodiment, in the tunneling oxide layer passivated contact solar cell, the mobility of the conductive layer is 2 cm 2 V -1 s-1 ~10 cm 2 V -1 s -1 and further can be 4 cm 2 V -1 s -1 ~6 cm 2 V -1 s -1 and can also be selected from any one of the following mobilities or an interval composed of any two of the mobilities: 2 cm 2 V -1 s -1 、4 cm 2 V -1 s -1 、6 cm 2 V -1 s -1 、8 cm 2 V -1 s -1 、10 m 2 V -1 s -1 etc.

[0080] In one embodiment, in the tunneling oxide passivated contact solar cell, the thickness of the conductive layer is 1 nm to 10 nm, further can be 1 nm to 5 nm, and can also be selected from any one of the following thicknesses or an interval composed of any two of the thicknesses: 1 nm, 2 nm, 3 nm, 4 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc. Optimizing the thickness of the conductive layer is beneficial to further improving the efficiency of the solar cell.

[0081] Figure 3 This is the structure of the tunneling oxide passivated contact solar cell in one embodiment of the present application, wherein the meanings of the reference numerals are as follows: silicon substrate 11, tunneling layer 21, first passivation layer 31, conductive layer 41, first electrode 51, P-type monocrystalline silicon layer 61, alumina layer 71, SiN:H layer 81, and second electrode 91; Figure 4 is Figure 3 the energy band matching diagram of the first passivation layer 31, the conductive layer 41 and the first electrode 51 on the back of the tunneling oxide passivated contact solar cell shown in Figure 5 This is the structure of the tunneling oxide passivated contact solar cell in the traditional technology, wherein the first electrode 52 passes through the SiN:H layer 42 and contacts the first passivation layer 32 (n-type polysilicon layer), Figure 6 is Figure 5 the energy band matching diagram of the first passivation layer 32 and the first electrode 52 on the back of the tunneling oxide passivated contact solar cell in the traditional technology shown in

[0082] Comparing can show that when using an ultra-thin conductive layer as the back contact layer of a TOPCon solar cell (as shown in Figure 3 ), the energy band structure at the interface between the first electrode 51 and the n-type polycrystalline silicon layer 31 (also denoted as the first passivation layer) bends downward, thereby preventing direct contact between the n-type polycrystalline silicon layer 31 (the first passivation layer) and the first electrode 51, which further leads to a reduction in the interface contact resistance and promotes the selective extraction of electrons (the black dots 101 in the energy band diagram represent electrons, and the white dots 102 represent holes); the conductive layer 41 reduces the contact resistance at the interface between the metal first electrode 51 and the n-type polycrystalline silicon layer 31 (the first passivation layer), thereby forming a strong hole blocking layer on the surface of the n-type polycrystalline silicon layer 31 (the first passivation layer); the ultra-thin conductive layer with a low work function optimizes the energy band matching of the n-type polycrystalline silicon layer 31 (the first passivation layer) / the conductive layer 41 / the first electrode 51, which helps to avoid energy loss and the recombination of carrier transport, and realizes the dual functions of electron selective transport and hole blocking.

[0083] In one embodiment, in the tunneling oxide layer passivated contact solar cell described above, the composition of the tunneling layer is SiO 2 , and the high-quality ultra-thin silicon oxide plus doped polycrystalline silicon layer realizes efficient passivation of the entire back surface of the cell and selective collection of carriers. Since there is no silicon / metal contact interface, it is beneficial to increase the open circuit voltage (abbreviated as Voc), and the collection of carriers over the entire area is beneficial to increase the fill factor (abbreviated as FF).

[0084] In one embodiment, in the tunneling oxide layer passivated contact solar cell described above, the first passivation layer is an n-type polycrystalline silicon layer, that is, n+poly-Si, and its function is to avoid direct contact between the tunneling layer and the conductive layer, or between the tunneling layer and the metal electrode, so as to prevent the diffusion of metal elements in the metal electrode into single crystal or polycrystal to generate recombination centers.

[0085] In the second aspect of the present application, a method for manufacturing the tunneling oxide layer passivated contact solar cell described in the first aspect is provided, including the following steps:

[0086] Provide a substrate for deposition; wherein, the substrate for deposition includes a silicon substrate, a tunneling layer, and an n-type polycrystalline silicon layer stacked in sequence;

[0087] Form a conductive layer and a metal electrode in sequence on the surface of the n-type polycrystalline silicon layer facing away from the tunneling layer, and manufacture the tunneling oxide layer passivated contact solar cell described in the first aspect.

[0088] The tunneling oxide layer passivated contact solar cell manufactured by the manufacturing method provided in the present application has a relatively high fill factor, current density, and energy conversion efficiency.

[0089] In one embodiment, reference may also be made to Figure 7 and Figure 1 , a method for preparing a tunnel oxide passivated contact solar cell, comprising the following steps:

[0090] Step S110: Provide a deposition substrate, which includes a silicon substrate 1, a tunnel layer 2, and an n-type polysilicon layer 3 arranged in a stacked manner;

[0091] Step S120: Sequentially form a conductive layer 4 and a metal electrode 5 on the surface of the n-type polysilicon layer 3 facing away from the tunnel layer 2 to prepare a tunnel oxide passivated contact solar cell.

[0092] Among them, the conductive layer 4 includes a TiN crystal phase, a TiO 2 crystal phase, and a titanium oxynitride crystal phase.

[0093] The tunnel oxide passivated contact solar cell prepared by the preparation method provided in this application has a high fill factor, current density, and energy conversion efficiency.

[0094] In one embodiment, in the method for preparing a tunnel oxide passivated contact solar cell, the conductive layer is formed on the surface of the n-type polysilicon layer facing away from the tunnel layer by a method including the following steps:

[0095] In an argon and nitrogen gas atmosphere, using a titanium target, perform DC magnetron sputtering on the surface of the n-type polysilicon layer facing away from the tunnel layer;

[0096] Form a conductive layer on the surface of the n-type polysilicon layer facing away from the tunnel layer by physical vapor deposition; among them, the partial pressure ratio of nitrogen to argon is (0.1 - 0.6):1; the power of DC magnetron sputtering is 100W - 300W.

[0097] It can be understood that the purity of nitrogen used in industrial production is 99.99%, which is mainly extracted from the air and generally contains a small amount of oxygen. Therefore, during the magnetron sputtering process, introducing a certain proportion of nitrogen and argon can obtain a conductive layer including a TiN crystal phase, a TiO 2 crystal phase, and a titanium oxynitride crystal phase. And in the vacuum chamber, as the partial pressure ratio of nitrogen to argon increases, both the nitrogen concentration and the oxygen concentration will increase, and Ti - O and N - O bonds are more likely to form, resulting in more other impurity phases. However, if the nitrogen partial pressure ratio is too low, the film quality will deteriorate. Therefore, in some embodiments, the partial pressure ratio of nitrogen to argon is controlled to be (0.1 - 0.6):1.

[0098] In one embodiment, in the preparation method, the reaction gases for forming the conductive layer include nitrogen and argon, and the partial pressure ratio of nitrogen to argon is (0.1 - 0.6):1. For example, the partial pressure ratio of nitrogen to argon can be but is not limited to 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, or the range composed of any two of these values. Optionally, the partial pressure ratio of nitrogen to argon is (0.1 - 0.3):1, and further optionally, the partial pressure ratio of nitrogen to argon is (0.1 - 0.2):1.

[0099] In one embodiment, reference can also be made to Figure 3 and Figure 8 , and the preparation method of the tunnel oxide passivated contact solar cell (A) is as follows:

[0100] Step S100: Provide an N-type monocrystalline silicon substrate 11; the N-type monocrystalline silicon substrate 11 has a front side and a back side facing away from each other; clean, damage-remove, and texture the front side and the back side of the N-type monocrystalline silicon substrate 11.

[0101] Step S200: Form a P-type monocrystalline silicon layer 61 on the front side of the N-type monocrystalline silicon substrate 11.

[0102] Specifically, the P-type monocrystalline silicon layer 61 is prepared by boron diffusion in combination with laser doping.

[0103] Step S300: Form a tunnel layer 21 on the back side of the N-type monocrystalline silicon substrate 11.

[0104] Step S400: Form a first passivation layer 31 on the surface of the tunnel layer 21 on the side facing away from the N-type monocrystalline silicon substrate 11, and anneal; the first passivation layer 31 is an n-type polysilicon.

[0105] In some of these embodiments, between step S300 and step S400, steps S302 and S304 may further be included. Specifically, step S302: Perform BSG removal treatment. Step S304: Perform back grinding treatment. Steps S302 and S304 can be common in the art and are not particularly limited herein.

[0106] Step S500: Form an aluminum oxide layer 71 on the side of the P-type monocrystalline silicon layer 61 facing away from the N-type monocrystalline silicon substrate 11.

[0107] In some of these embodiments, between step S400 and step S500, step S402 may further be included. Specifically, step S402: Perform de-plating treatment on the side of the P-type monocrystalline silicon layer 61 facing away from the N-type monocrystalline silicon substrate 11 to ensure that the battery has no leakage. It can be understood that step S402 can be common in the art and is not particularly limited herein.

[0108] Step S600: Form an antireflection layer 81 on the side of the alumina layer 71 facing away from the P-type single-crystalline silicon layer 61.

[0109] Step S700: Form a conductive layer 41 on the surface of the first passivation layer 31 on the side facing away from the tunneling layer 21.

[0110] The specific method is to use the PVD (Physical Vapor Deposition) method to prepare the conductive layer 41 on the surface of the first passivation layer 31 on the side facing away from the tunneling layer by DC magnetron sputtering. The target is a pure titanium target (99.99%), the temperature is room temperature, the base pressure is 5×10 -4 Pa, and the working gases are high-purity Ar (99.99%) and high-purity N 2 (99.99%); the power is 200 W, the deposition pressure is 0.4 Pa, and the concentration of N in the working gas in the deposition chamber is 10%. Deposit the conductive layer film; the conductive layer includes a TiN crystal phase with an atomic number ratio of 40%, a TiO 2 crystal phase with an atomic number ratio of 30%, and a TiO 2 crystal phase with an atomic number ratio of 30% and a TiO x N y crystal phase, the conductivity is 5000 S / cm, the work function is 4.26 eV, the carrier concentration is 7×10 21 cm 3 , the mobility is 4.5 cm 2 V -1 s -1 , and the thickness is 1 nm.

[0111] Step S800: Form a first electrode 51 on the surface of the conductive layer 41 on the side facing away from the first passivation layer 31.

[0112] The specific method is to prepare 0.05 g of Ag by electron beam thermal evaporation technology under the condition of 0.05 Pa of Ar (99.99%), and deposit a silver electrode (i.e., the first electrode 51) on the back of the cell.

[0113] Step S900: Form a second electrode 91 on the surface of the P-type single-crystalline silicon layer 61 on the side facing away from the alumina layer 81, and obtain a tunneling oxide passivated contact solar cell (A).

[0114] In one embodiment, the preparation method of the tunneling oxide passivated contact solar cell (B) is basically the same as the preparation method of the tunneling oxide passivated contact solar cell (A), except that in Step S700:

[0115] Step S700: Form a conductive layer 41 on the surface of the first passivation layer 31 on the side facing away from the tunneling layer.

[0116] The specific method is to use the PVD (Physical Vapor Deposition) method to prepare the conductive layer 41 on the surface of the first passivation layer 31 facing away from the tunneling layer by direct current magnetron sputtering. The target is a pure titanium target (99.99%), the temperature is room temperature, and the base pressure is 5×10 -4 Pa, and the raw materials are high-purity Ar (99.99%) and high-purity N 2 (99.99%); the deposition pressure is 0.4 Pa, and the concentration of N in the reaction gas in the deposition chamber is 20% to deposit the conductive layer film; the conductive layer includes a TiN crystal phase with an atomic number ratio of 30%, a TiO 2 crystal phase with an atomic number ratio of 35%, and a TiO 2 crystal phase with an atomic number ratio of 35% and an N x crystal phase. The conductivity of the conductive layer is 4800 S / cm, the work function is 4.29 eV, the carrier concentration is 6×10 y cm 21 cm 3 , the mobility is 5 cm 2 V -1 s -1 , and the thickness is 5 nm.

[0117] In one embodiment, the preparation method of the tunneling oxide passivated contact solar cell (C) is basically the same as the preparation method of the tunneling oxide passivated contact solar cell (A), except for step S700:

[0118] Step S700: Form a conductive layer 41 on the surface of the first passivation layer 31 facing away from the tunneling layer.

[0119] The specific method is to use the PVD (Physical Vapor Deposition) method to prepare the conductive layer 41 on the surface of the first passivation layer 31 facing away from the tunneling layer by direct current magnetron sputtering. The target is a pure titanium target (99.99%), the temperature is room temperature, and the base pressure is 5×10 -4 Pa, and the raw materials are high-purity Ar (99.99%) and high-purity N 2 (99.99%); the deposition pressure is 0.4 Pa, and the concentration of N in the reaction gas in the deposition chamber is 35% to deposit the conductive layer film; the conductive layer includes a TiN crystal phase with an atomic number ratio of 20%, a TiO 2 crystal phase with an atomic number ratio of 35%, and a TiO 2 crystal phase with an atomic number ratio of 45% and an N x crystal phase. The conductivity of the conductive layer is 3580 S / cm, the work function is 4.31 eV, the carrier concentration is 4×10 y cm 21 cm 3 , the mobility is 5.6 cm 2 V -1s -1 , with a thickness of 10 nm.

[0120] In one embodiment, a method for fabricating a tunnel oxide passivated contact solar cell (D) has substantially the same fabrication steps as the method for fabricating a tunnel oxide passivated contact solar cell (A), except that it does not include step S700, i.e., there is no conductive layer.

[0121] The spectral response test of the solar cell is carried out in accordance with GB 11009-1989, the single crystal cell test is carried out in accordance with GB 12632-1990, and the photovoltaic current-voltage characteristics test of the solar cell is carried out in accordance with 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 2.

[0122] Table 1 Preparation parameters of the conductive layers of solar cells (A) to (D)

[0123]

[0124] Table 2 Performance comparison of solar cells (A) to (D)

[0125]

[0126] In Table 2, for solar cell (A): the performance of solar cell (D) means that the contact resistance of solar cell (A) with a conductive layer added is reduced by 0.45 mΩ·cm compared to solar cell (D) without a conductive layer 2 , the current is increased by 80 mA, the fill factor is increased by 0.30%, and the photoelectric conversion efficiency is increased by 0.21%. Similarly, the contact resistances of solar cell (B) and solar cell (C) relative to solar cell (D) are reduced by 0.13 and 0.03 mΩ·cm respectively 2 , the currents are increased by 53 mA and 12 mA respectively, the fill factors are increased by 0.15% and 0.10% respectively, and the photoelectric conversion efficiencies are increased by 0.125% and 0.040% respectively.

[0127] It can be seen from this that when using an ultrathin conductive layer as the back contact layer of the TOPCon solar cell, the current collection effect of the back silver electrode is improved, the contact resistivity is reduced, the FF and current density of the cell are increased, and the cell efficiency is also significantly improved. By controlling the relative content of the TiN crystal phase and other crystal phases, the current collection effect of the back silver electrode is further improved, the contact resistance is reduced, thereby increasing the fill factor, current density and energy conversion efficiency of the solar cell.

[0128] Understandably, in the step S100, the purpose of the cleaning process is to 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, and it 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)

[0129] Understandably, in the step S100, the purpose of the texturing process is to form a non-smooth structure with uniform size on the surface of the silicon wafer. This non-smooth structure presents a similar pyramid structure in the microscopic morphology, and millions of tetrahedral pyramids can be formed on the silicon surface per square centimeter. This treatment can enable the incident light to increase the absorption of light through the pyramid structure on its surface when entering the silicon wafer surface from different angles, 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 pyramids 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 pyramids that make up the pyramid texture on the silicon wafer surface, so that the sharp square pyramids on the surface of the tetrahedral pyramid structure become smooth square pyramid-like structures; an acidic solution such as HF can also be used to remove the oxide layer on the surface of the pyramid texture.

[0130] Understandably, in the step S100, 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, cleaning can be carried out again according to design and process requirements.

[0131] Understandably, in the step S200, the process of preparing the P-type monocrystalline silicon layer is also collectively referred to as boron diffusion, which can be the common method in the art and will not be elaborated here; in this application, there is no limitation on the method of preparing the P-type monocrystalline silicon layer, and it can be prepared by using one-time boron diffusion combined with laser doping, two-time boron diffusion combined with laser doping, laser opening film combined with two-time boron diffusion, laser grooving + boron paste printing, or wet etching + two-time boron diffusion to obtain the N-type monocrystalline silicon layer.

[0132] Understandably, in the steps S800 and S900, the specific method for preparing the electrodes in the present application is not limited. The method for forming the first electrode layer 51 and the second electrode layer 91 can adopt screen printing combined with sintering method, or electroplating method, or laser transfer printing method, thermal evaporation plating, etc.

[0133] 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.

[0134] In the third aspect of the present application, there is provided an electrical device including the tunneling oxide passivation contact solar cell described in the first aspect or the tunneling oxide passivation contact solar cell prepared by the preparation method described in the second aspect.

[0135] In the fourth aspect of the present application, there is provided an application of the tunneling oxide passivation contact solar cell described in the first aspect or the tunneling oxide passivation contact 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.

[0136] The tunneling oxide passivation contact solar cell provided in the present application can utilize light energy with high efficiency in photovoltaic applications.

[0137] 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-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0138] 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 belong to 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 drawings can be used to explain the content of the claims.

Claims

1. A tunnel oxide passivation contact solar cell, characterized in that: It comprises a silicon substrate and a tunneling layer, an n-type polysilicon layer, a conductive layer and a metal electrode which are sequentially stacked on one side surface of the silicon substrate; The conductive layer includes a TiN crystal phase, a TiO2 crystal phase and a titanium oxynitride crystal phase.

2. The tunnel oxide passivation contact solar cell according to claim 1, characterized in that: The metal electrode is selected from at least one of Ag and Al; Optionally, the metal electrode is an Ag electrode.

3. The tunnel oxide passivation contact solar cell according to claim 1, characterized in that: In the conductive layer, the atomic number of the TiN crystal phase accounts for 20% to 50%, the atomic number of the TiO2 crystal phase accounts for ≤40%, and the atomic number of the titanium oxynitride crystal phase accounts for ≤45%; Optionally, in the conductive layer, the atomic number of the TiN crystal phase accounts for 30% to 50%, the atomic number of the TiO2 crystal phase accounts for 20% to 40%, and the atomic number of the titanium oxynitride crystal phase accounts for 20% to 40%.

4. The tunnel oxide passivation contact solar cell according to claim 3, characterized in that: In the conductive layer, at least a portion of the TiN crystal phase is face-centered cubic and has a (111) crystal plane; Optionally, the percentage of the TiN crystal phase having the (111) crystal plane in the total TiN crystal phase is 10% to 90%; Optionally, the atomic percentage of the TiN crystal phase having the (111) crystal plane in the entire TiN crystal phase is 30% to 70%.

5. The tunnel oxide passivation contact solar cell according to claim 3, characterized in that: In the conductive layer, at least a portion of the TiO2 crystal phase is in anatase-type tetragonal system or brookite-type orthorhombic system.

6. The tunnel oxide passivation contact solar cell according to any one of claims 1 to 5, characterized in that: Satisfy one or more of the following characteristics: (1) The conductivity of the conductive layer is 0.5S / cm to 7600S / cm; (2) The work function of the conductive layer is 4.0 eV to 5.4 eV; (3) The carrier concentration of the conductive layer is 1×10 21 cm 3 ~9×10 21 cm 3 ; (4) The mobility of the conductive layer is 2 cm 2 V -1 s -1 ~10cm 2 V -1 s -1 .

7. The tunnel oxide passivation contact solar cell according to claim 6, characterized in that: Satisfy one or more of the following characteristics: (1) The conductivity of the conductive layer is 3000S / cm to 6000S / cm; (2) The work function of the conductive layer is 4.2 eV to 4.3 eV; (3) The carrier concentration of the conductive layer is 6×10 21 cm 3 ~8×10 21 cm 3 ; (4) The mobility of the conductive layer is 4 cm 2 V -1 s -1 ~6cm 2 V -1 s -1 .

8. The tunnel oxide passivated contact solar cell according to any one of claims 1 to 5 and 7, characterized in that: The thickness of the conductive layer is 1 nm to 10 nm; Optionally, the thickness of the conductive layer is 1 nm to 5 nm.

9. A method for preparing a tunnel oxide passivation contact solar cell, characterized in that: The following steps are involved: Providing a deposition substrate; wherein the deposition substrate comprises a silicon base, a tunneling layer and an n-type polysilicon layer stacked in sequence; forming a conductive layer and a metal electrode in sequence on a surface of the n-type polysilicon layer facing away from the tunneling layer to prepare a tunneling oxide layer passivated contact solar cell; Wherein, the conductive layer includes TiN crystal phase, TiO2 crystal phase and titanium oxynitride crystal phase.

10. The preparation method according to claim 9, characterized in that: The conductive layer is formed on a surface of the n-type polysilicon layer facing away from the tunnel layer by a method comprising the following steps: In an argon and nitrogen atmosphere, using a titanium target, direct current magnetron sputtering is performed on a surface of the n-type polysilicon layer on a side away from the tunneling layer; forming the conductive layer on the surface of the n-type polysilicon layer facing away from the tunnel layer by physical vapor deposition; The partial pressure ratio of nitrogen to argon is (0.1-0.6):1, and the power of the DC magnetron sputtering is 100W-300W.

11. An electrical device, characterized in that: The invention comprises the tunneling oxide layer passivation contact solar cell according to any one of claims 1 to 8 or the tunneling oxide layer passivation contact solar cell prepared by the preparation method according to claim 9 or 10.

12. Use of the tunneling oxide passivation contact solar cell according to any one of claims 1 to 8, or the tunneling oxide passivation contact solar cell prepared by the preparation method according to claim 9 or 10, or the electrical equipment according to claim 11 in photovoltaic power generation.

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