A window layer of a solar cell, a solar cell and a method for preparing the same

Abstract

The present invention discloses a window layer of a solar cell, a solar cell and a preparation method thereof. It relates to the field of solar cell manufacturing and solves the problems of poor conductivity and crystallization stability of the window layer. The window layer of the solar cell is an N-type hydrogenated carbon silicon oxide thin film, and the chemical formula of the N-type hydrogenated carbon silicon oxide thin film is nc-Si x C y :H, which is in a nanocrystalline state. Among them, the range of the non-stoichiometric ratio x is 0.1 to 0.5, and the range of the non-stoichiometric ratio y is 0.25 to 1. The nanocrystalline N-type hydrogenated carbon silicon oxide thin film has better crystallinity and conductivity, and at the same time has a wide optical band gap. The window layer of the solar cell can improve the photoelectric conversion efficiency. The preparation method of the window layer of the solar cell is used to prepare the window layer, and the preparation method of the solar cell is used to prepare the solar cell.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell manufacturing, and in particular to a window layer of a solar cell, a solar cell and a preparation method thereof. Background Art

[0002] In the past decade, nanocrystalline silicon has been widely used in solar cells due to its excellent optoelectronic properties, such as high conductivity, adjustable optical band gap, and good stability. Among them, hydrogenated nanocrystalline silicon films formed by doping O atoms or C atoms in various nanocrystalline silicon films are very promising materials for constructing the window layer of solar cells.

[0003] At present, silicon heterojunction solar cells are mainly prepared by introducing SiH4, H2, CO2, and PH3 into the process chamber to prepare phosphorus-doped N-type nc-SiO x :H film is used as a window layer, due to SiO x The substrate has a high barrier height, making nc-SiO x :H film has a high resistivity, which is not conducive to the collection of carriers in solar cells and has poor conductivity. x :H film is used as a window layer and SiO x Compared with the substrate, SiC x Although the substrate has a high carrier mobility, SiC x The length and polarity of Si-Si bonds in the matrix are relatively low, making nanocrystalline silicon x Phase separation and accumulation in the matrix are difficult, and the crystallinity is poor. Summary of the invention

[0004] The object of the present invention is to provide a window layer of a solar cell, a solar cell and a preparation method thereof, so as to improve the conductivity and crystal stability of the film.

[0005] In a first aspect, the present invention provides a window layer of a solar cell, wherein the window layer is an N-type hydrogenated carbon oxide silicon film, and the chemical formula of the N-type hydrogenated carbon oxide silicon film is nc-SiO x C y :H, which is in a nanocrystalline state, wherein the non-stoichiometric ratio x is in the range of 0.1 to 0.5, and the non-stoichiometric ratio y is in the range of 0.25 to 1.

[0006] When the above technical solution is adopted, the window layer of the solar cell is a nanocrystalline N-type hydrogenated carbon oxide silicon film formed by simultaneously doping oxygen atoms and carbon atoms into the nanocrystalline silicon film. The nanocrystalline N-type hydrogenated carbon oxide silicon film combines SiO x Substrate and SiC y The advantages of the substrate, among which SiO xThe matrix can achieve optimal thermodynamic phase separation and has high amorphous phase stability at high temperatures; SiC y The matrix has a high carrier mobility and high conductivity. Therefore, the nanocrystalline N-type hydrogenated carbon oxide silicon film has better crystallinity and conductivity, and also has a wide optical band gap. As a window layer of a solar cell, it can better improve the photoelectric conversion efficiency.

[0007] In a second aspect, the present invention further provides a method for preparing a window layer of a solar cell, comprising:

[0008] providing a substrate;

[0009] An N-type hydrogenated silicon carbide oxide film is deposited on the first surface of the substrate by using a hot wire chemical vapor deposition (HWCVD) method, and the N-type hydrogenated silicon carbide oxide film forms the above-mentioned window layer.

[0010] When the above technical solution is adopted, an N-type hydrogenated carbon oxide silicon thin film is deposited on the first surface of the substrate by a hot wire chemical vapor deposition method to form a window layer of the solar cell. The hot wire chemical vapor deposition method uses a hot wire high-temperature catalytic process to form a free radical on the substrate to form a film. Compared with the existing plasma enhanced chemical vapor deposition (PECVD) method for coating a film on a substrate, the substrate is easily damaged and causes defects under the bombardment of plasma, which reduces the performance of the battery. The hot wire chemical vapor deposition method will not cause damage to the substrate during the coating process; and the hot wire chemical vapor deposition method has a high dissociation efficiency for the process gas, and can easily dissociate the gas containing carbon atoms. The prepared N-type hydrogenated carbon oxide silicon thin film has a high crystallization rate, does not require a large amount of H2, and has a very low cost; the hot wire chemical vapor deposition method has a simple process, a high film doping efficiency, and does not require an additional heat treatment process.

[0011] Optionally, in the above-mentioned window layer preparation method, the precursor gas for forming the N-type hydrogenated silicon oxycarbon film includes a silicon source gas, a hydrogen source gas, an oxygen source gas, a carbon source gas, and a nitrogen source gas. In this way, the N-type hydrogenated silicon oxycarbon film is prepared in one step by a precursor gas containing silicon atoms, hydrogen atoms, oxygen atoms, carbon atoms, and nitrogen atoms, thereby obtaining high conductivity.

[0012] Optionally, in the above-mentioned window layer preparation method, the oxygen source gas includes N2O. In this way, the precursor gas can provide not only oxygen atoms but also nitrogen atoms through N2O, thereby reducing the types of gases and thus reducing the storage cost of the gases.

[0013] Optionally, in the above-mentioned thin film preparation method, the nitrogen source gas includes N2.

[0014] When the above technical solution is adopted, nitrogen atoms are provided by N2 and N2 is doped. This is because the process chamber itself contains trace amounts of N2, and the high temperature of the hot wire can also catalyze the dissociation of N2. N2 has the same doping effect as phosphine, so the introduction of additional impurity gases is avoided. In addition, N2 has a wide source and is non-toxic, harmless and pollution-free.

[0015] Optionally, in the above-mentioned window layer preparation method, before forming the N-type hydrogenated silicon carbide oxide film, the step of forming an amorphous silicon film on at least one surface of the substrate is further included. Such a configuration is conducive to improving the passivation effect of the substrate.

[0016] Optionally, in the above-mentioned window layer preparation method, before forming the N-type hydrogenated carbon oxide silicon film, the step of forming a seed layer on the first surface of the substrate by a hot wire chemical vapor deposition method using silicon source gas and hydrogen source gas is further included. When the above-mentioned technical solution is adopted, before preparing the N-type hydrogenated carbon oxide silicon film, a seed layer is first deposited on the substrate. By setting the seed layer, the nucleation points on the substrate are increased, which is conducive to the deposition and growth of the N-type hydrogenated carbon oxide silicon film.

[0017] In a third aspect, the present invention further provides a method for preparing a solar cell, comprising any of the above methods for preparing a window layer.

[0018] Since the preparation method of the solar cell adopts the window layer preparation method of the present application, it has the same beneficial effects as the thin film preparation method, which will not be described in detail here.

[0019] Optionally, in the above-mentioned method for preparing a solar cell, the substrate is N-type, and further comprises the steps of:

[0020] forming a P-type emitter layer on the second surface of the substrate;

[0021] forming a transparent conductive layer on the surfaces of the N-type hydrogenated silicon oxycarbon film and the P-type emitter layer; and

[0022] Metal electrodes are formed on the surfaces of the transparent conductive layer located on the first surface and the second surface.

[0023] When the above technical solution is adopted, the N-type hydrogenated carbon oxide silicon film is used as the window layer of the solar cell, which has higher conductivity and wider optical band gap, thereby improving the performance of the solar cell.

[0024] In a fourth aspect, the present invention further provides a solar cell, comprising:

[0025] An N-type substrate; and

[0026] The N-type hydrogenated silicon oxycarbide film formed on the first surface of the substrate serves as a window layer, and the N-type hydrogenated silicon oxycarbide film is the film mentioned above.

[0027] When the above technical solution is adopted, since the N-type hydrogenated silicon carbide film of the solar cell adopts the nanocrystalline hydrogenated silicon carbide film in this application as the window layer of the solar cell, it has the same beneficial effects as the hydrogenated silicon carbide film, which will not be repeated here.

[0028] Optionally, in the above solar cell, it further comprises:

[0029] A P-type emitter layer formed on the second surface of the substrate;

[0030] A transparent conductive layer formed on the N-type hydrogenated silicon oxycarbon film and the P-type emitter layer respectively; and

[0031] A metal electrode is formed on the transparent conductive layer.

[0032] When the above technical solution is adopted, the solar cell is a silicon heterojunction cell.

[0033] Optionally, in the above solar cell, a passivation layer is provided between the first surface of the substrate and the N-type hydrogenated silicon carbide oxide film, and / or a passivation layer is provided between the second surface of the substrate and the P-type emitter layer.

[0034] When the above technical solution is adopted, the generation of interface defects of the substrate is reduced by the passivation layer, thereby reducing the recombination of carriers caused by the defects and improving the photoelectric conversion efficiency.

[0035] Optionally, in the above solar cell, the passivation layer is an intrinsic amorphous silicon layer. Such a configuration is beneficial to improving the passivation effect of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0037] Figure 1 A schematic diagram of the structure of a solar cell provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of a process for preparing a thin film of a solar cell provided by an embodiment of the present invention;

[0039] Figure 3 A schematic flow chart of step S200 of a method for preparing a thin film of a solar cell provided by an embodiment of the present invention;

[0040] Figure 4 A schematic flow chart of another method for preparing a thin film of a solar cell provided by an embodiment of the present invention;

[0041] Figure 5 A schematic flow chart of a method for preparing a solar cell provided in an embodiment of the present invention.

[0042] Figure numerals: 10 - substrate, 100 - N-type single crystal silicon wafer, 101 - first passivation layer, 102 - second passivation layer, 20 - N-type hydrogenated carbon dioxide silicon film, 30 - first transparent conductive layer, 40 - first metal electrode, 50 - P-type back emitter layer, 60 - second transparent conductive layer, 70 - second metal electrode. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0046] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] At present, silicon heterojunction solar cells are mainly prepared by introducing SiH4, H2, CO2, and PH3 into the process chamber to prepare boron-doped N-type nc-SiO x :H film is used as a window layer, due to SiO x The substrate has a high barrier height, making nc-SiO x :H film has a high resistivity, which is not conducive to the collection of carriers in solar cells and has poor conductivity. x :H film is used as a window layer and SiO x Compared with the substrate, SiC x Although the substrate has a high carrier mobility, SiC x The length and polarity of Si-Si bonds in the matrix are relatively low, making nanocrystalline silicon x Phase separation and accumulation in the matrix are difficult, and the crystallinity is poor.

[0049] In order to solve the above problems, the present invention provides a window layer of a solar cell, wherein the window layer is an N-type hydrogenated carbon oxide silicon film, and the chemical formula of the N-type hydrogenated carbon oxide silicon film is nc-SiO x C y :H, which is nanocrystalline, hereinafter referred to as nc-SiO x C y :H film, wherein the non-stoichiometric ratio x ranges from 0.1 to 0.5, the non-stoichiometric ratio y ranges from 0.25 to 1, and the non-stoichiometric ratios x and y both represent the percentage of the flow rate of the gas containing the doping element to the total flow rate of the gas introduced into the process chamber.

[0050] When the above technical solution is adopted, the window layer of the solar cell is nc-SiO formed by simultaneously doping oxygen atoms and carbon atoms into the nanocrystalline silicon film. x C y :H thin film, the nc-SiO x C y :H thin film fused with SiO x Substrate and SiC y The advantages of the substrate, among which SiO xThe matrix can achieve optimal thermodynamic phase separation and has high amorphous phase stability at high temperatures; SiC y The matrix has high carrier mobility and high conductivity. x C y :H film has better crystallinity and conductivity, and also has a wide optical band gap. It is used as the window layer of solar cells. The window layer refers to the place where the solar cell first passes light. x C y :H film has good conductivity and wide optical band gap, which can better improve the photoelectric conversion efficiency.

[0051] When nc-SiO x C y :H film can be used as the window layer of solar cells, and can be applied to a variety of solar cells, such as silicon heterojunction cells, tunnel oxide passivated contact (TOPCon) cells, stacked cells, etc. x C y :H thin film is a thin film prepared under low temperature process, and silicon heterojunction cell is also a solar cell prepared under low temperature process. Therefore, nc-SiO x C y :H film is a better choice for the window layer of silicon heterojunction cells. x C y When H thin film is used as the window layer of other solar cells, temperature control during the preparation process needs to be considered. For solar cells with high temperature processes, such as TOPCON cells, it is necessary to control the temperature during the preparation of nc-SiO x C y :H thin film window layer, a high temperature process is performed first, and then nc-SiO x C y :H film to avoid high temperature to nc-SiO x C y :H film destruction.

[0052] like Figure 1 and Figure 2 As shown, an embodiment of the present invention also provides a method for preparing a window layer of a solar cell, comprising the following steps:

[0053] In step S100 , a substrate 10 is provided and the substrate 10 is placed on a carrier. Usually, the substrate 10 is made of a silicon substrate, and a light incident surface of the silicon substrate has a suede structure.

[0054] Step S200, a N-type hydrogenated carbon oxide silicon film 20 is deposited on the first surface (light incident surface) of the substrate by hot wire chemical vapor deposition (HWCVD) as a window layer. The window layer is the window layer described in the above embodiment, i.e., nc-SiO x C y :H film.

[0055] An N-type hydrogenated silicon carbide thin film 20 is deposited on the first surface of the substrate 10 by a HWCVD process. The HWCVD process utilizes a hot wire high-temperature catalytic process to cause the gas to form free radicals and deposit on the substrate to form a film. Compared with the existing method of coating a film on a substrate by plasma enhanced chemical vapor deposition (PECVD), the substrate is easily damaged and causes defects under the bombardment of plasma, which reduces the battery performance. However, the HWCVD process does not damage the substrate during the coating process. Moreover, HWCVD has a high dissociation efficiency for process gases and can easily dissociate gases containing carbon atoms. The prepared N-type hydrogenated silicon carbide thin film 20 has a high crystallization rate and does not require a large amount of H2, so the cost is very low. The HWCVD method has a simple process, a high film doping efficiency, and does not require an additional heat treatment process.

[0056] Furthermore, in this embodiment, the precursor gas for forming the N-type hydrogenated silicon oxycarbon film 20 includes a silicon source gas, a hydrogen source gas, an oxygen source gas, a carbon source gas, and a nitrogen source gas. In this way, the N-type hydrogenated silicon oxycarbon film 20 is prepared in one step by using a precursor gas containing silicon atoms, hydrogen atoms, oxygen atoms, carbon atoms, and nitrogen atoms, thereby obtaining high electrical conductivity.

[0057] Specifically, the silicon source gas may be SiH4, the hydrogen source gas may be SiH4, H2 and / or CH4, the oxygen source gas may be N2O, the carbon source gas may be CH4, and the nitrogen source gas may be N2O and / or N2. In this way, N2O in the precursor gas can provide not only oxygen atoms but also nitrogen atoms, thereby reducing the types of gases and thus reducing the storage cost of the gases.

[0058] Nitrogen atoms are provided by N2 and doped with N2 because the process chamber itself contains trace amounts of N2. The high temperature of the hot wire can also catalyze the dissociation of N2. N2 has the same doping effect as phosphine, so the introduction of additional impurity gases is avoided. In addition, N2 has a wide source and is non-toxic, harmless and pollution-free.

[0059] like Figure 3As shown, forming an N-type hydrogenated silicon carbide film 20 on the first surface by HWCVD deposition specifically includes the following steps:

[0060] Step S201, placing the substrate 10 in a process chamber and evacuating the process chamber;

[0061] Step S202, introducing precursor gas into the process chamber, the precursor gas including SiH4, H2, N2O, CH4 and N2;

[0062] Step S203, using a hot wire to heat, so that the precursor gas is deposited on the first surface of the substrate 10 by HWCVD to form an N-type hydrogenated silicon carbide film 20, namely nc-SiO x C y :H film, maintain heating time 200S ~ 500s.

[0063] Exemplarily, the process conditions are as follows: the SiH4 flow rate can be 10sccm~50sccm (standard cubic centimeter per minute, volume flow unit, representing standard milliliters per minute), the H2 flow rate can be 300sccm~1000sccm, the N2O flow rate can be 5sccm~30sccm, the CH4 flow rate can be 5sccm~30sccm, the N2 flow rate can be 10sccm~50sccm, the process pressure can be 1pa~10pa, the process temperature can be 200℃~300℃, and the hot wire temperature can be 1600℃~1950℃.

[0064] It can be seen that before HWCVD deposition, the process chamber is first evacuated to ensure that the process environment is not polluted and improve the quality of the deposited coating.

[0065] As an optimization, the pressure in the process chamber after vacuuming is 4.0×10 -4 pa~6.0×10 -6 The lower the pressure after vacuuming, the more conducive it is to the purification of the process environment and the collision of doping atoms, thus improving the film quality and deposition efficiency.

[0066] For example, the pressure of the process chamber after evacuation may be 4.0×10 -4 pa, 5.0×10 -6 pa, 6.0×10 - 6 The pressure value pa, etc. can be selected according to the need of vacuum degree and is not limited to the pressure values ​​listed in this embodiment.

[0067] like Figure 4 As shown, in this embodiment, before placing the substrate 10 in the process chamber in step S100, the following steps are also included:

[0068] Step S090, evacuate the process chamber; specifically, the pressure of the process chamber after evacuation is 4.0×10 -4 pa~6.0×10 -6 pa.

[0069] Step S091 , placing a carrier for carrying the substrate 10 into a process chamber.

[0070] Step S092, introduce SiH4 into the process chamber, use the hot wire to heat, and chemically vapor deposit a layer of amorphous silicon film on the carrier and the inner wall of the process chamber. Specifically, the SiH4 flow rate can be 100sccm to 500sccm, the process pressure can be 2Pa to 10Pa, the process temperature can be 200℃ to 300℃, and the hot wire can be 1400℃ to 1600℃;

[0071] Step S093, preheating the carrier. Specifically, the carrier is placed in the HWCVD preheating chamber, kept there for 3 minutes to 10 minutes, and then taken out of the HWCVD preheating chamber.

[0072] Through the above steps, it can be known that before placing the substrate 10 in the process chamber in step S100, a layer of amorphous silicon film is first deposited on the surface of the carrier and the process chamber, so that the impurities on the surface of the carrier and the process chamber are covered by the amorphous silicon film, thereby protecting the substrate 10 from being contaminated during subsequent deposition, and improving the molding quality of the N-type hydrogenated silicon carbide film 20. After the coating of the carrier is completed, the carrier is preheated first, and then the substrate 10 is placed on the carrier, and the surface of the substrate 10 covered by the carrier can also be heated to avoid uneven heating of the substrate 10 in the future, which affects the deposition effect.

[0073] In this embodiment, before forming the N-type hydrogenated silicon carbide oxide film 20, a step is further included: forming an amorphous silicon film on at least one surface of the substrate. Such a configuration is beneficial to improving the passivation effect of the substrate.

[0074] Furthermore, in this embodiment, before forming the N-type hydrogenated silicon carbide oxide film 20, a step is also included: using silicon source gas and hydrogen source gas to form a seed layer on the first surface of the substrate by a hot wire chemical vapor deposition method.

[0075] Specifically, in this embodiment, after placing the substrate 10 in the process chamber in step S100, evacuating the process chamber, and before introducing the precursor gas into the process chamber in step S200, the following steps are also included:

[0076] Step S101, start preheating of the hot wire, specifically, preheating for 30s to 60s.

[0077] Step S102, SiH4 and H2 are introduced into the process chamber, and a seed layer is formed by hot wire chemical vapor deposition on the first surface of the substrate 10. Specifically, the SiH4 flow rate can be 10 sccm to 50 sccm, the H2 flow rate can be 300 sccm to 1000 sccm, the process pressure can be 1 Pa to 10 Pa, the process temperature can be 200°C to 300°C, and the hot wire temperature can be 1600°C to 1950°C.

[0078] Since it is not easy to directly deposit a nanocrystalline N-type hydrogenated silicon carbide film 20 on the light incident surface of the substrate 10, before preparing the N-type hydrogenated silicon carbide film 20, a seed layer is first deposited on the substrate 10. The seed layer is microcrystalline and has more nucleation points, which is beneficial to the subsequent deposition and growth of the nanocrystalline N-type hydrogenated silicon carbide film 20.

[0079] like Figure 5 As shown, the embodiment of the present invention also provides a method for preparing a solar cell, including the method for preparing a window layer as described in any of the above embodiments. That is, when preparing the window layer of the solar cell, the N-type nc-SiO x C y :H thin film preparation method as window layer.

[0080] Since the preparation method of the solar cell adopts the window layer preparation method in the present application, it has the same beneficial effects as the window layer preparation method, which will not be described in detail here.

[0081] like Figure 1 and Figure 5 As shown, further, in this embodiment, the substrate is an N-type substrate, specifically an N-type silicon substrate, and after the hot wire heating is used in step S200 to make the precursor gas form the N-type hydrogenated carbon oxide silicon film 20 by hot wire chemical vapor deposition on the first surface of the substrate 10, the following steps are also included:

[0082] Step S300 , forming a P-type emitter layer 50 on one side of the second surface (backlight side) of the substrate 10 .

[0083] In step S400 , a transparent conductive layer is formed on the surfaces of the N-type hydrogenated silicon oxycarbon film 20 and the P-type emitter layer 50 .

[0084] Step S500 , forming metal electrodes on the surfaces of the transparent conductive layer located on the first surface and the second surface respectively.

[0085] For example, a silicon heterojunction cell is used as an example to illustrate:

[0086] Step S200, depositing N-type nc-SiO on the light incident surface of the N-type substrate 10 xC y :H film;

[0087] Step S300, depositing a P-type emitter layer 50 on the backlight side of the N-type substrate 10 by PECVD, wherein the P-type emitter layer 50 is a P-type doped layer;

[0088] Step S400, in N-type nc-SiO x C y A first transparent conductive layer 30 is deposited on the H film, and a second transparent conductive layer 60 is deposited on the P-type emitter layer 50. The materials of the first transparent conductive layer 30 and the second transparent conductive layer 60 can be one or more of indium tin oxide (ITO), tungsten-doped indium oxide (In2O3:W, abbreviated as IWO), indium zinc oxide (IZO), and titanium-doped indium oxide (ITiO), but are not limited thereto. The materials of the first transparent conductive layer 30 and the second transparent conductive layer 60 can be the same or different;

[0089] Step S500, forming a first metal electrode 40 on the first transparent conductive layer 30, and forming a second metal electrode 70 on the second transparent conductive layer 60; the material of the first metal electrode 40 and the second metal electrode 70 can be one or more of Ag, Al, Cu, and W, but is not limited thereto. The materials of the first metal electrode 40 and the second metal electrode 70 can be the same or different.

[0090] When the above technical solution is adopted, the N-type hydrogenated carbon oxide silicon film 20 is used as the window layer of the solar cell, which has higher conductivity and wider optical band gap, thereby improving the performance of the solar cell.

[0091] like Figure 1 As shown, the embodiment of the present invention further provides a solar cell, comprising an N-type substrate 10 and a window layer, wherein the window layer is an N-type hydrogenated carbon oxide silicon film 20, the N-type hydrogenated carbon oxide silicon film 20 is formed on the first surface of the substrate 10, and the N-type hydrogenated carbon oxide silicon film 20 is the above-mentioned film, that is, N-type nc-SiO x C y :H film.

[0092] When the above technical solution is adopted, since the N-type hydrogenated silicon carbide film 20 of the solar cell adopts the nanocrystalline hydrogenated silicon carbide film in this application as the window layer of the solar cell, it has the same beneficial effects as the hydrogenated silicon carbide film, which will not be repeated here.

[0093] In some possible embodiments, the solar cell includes, in addition to the N-type substrate 10 and the N-type hydrogenated silicon oxycarbon film 20 formed on the first surface of the substrate 10, further including:

[0094] A P-type emitter layer 50 formed on the second surface of the substrate 10;

[0095] A transparent conductive layer formed on the N-type hydrogenated silicon carbide oxide film 20 and the P back emitter layer 50 respectively;

[0096] A metal electrode is formed on the transparent conductive layer.

[0097] Thus, the solar cell is a silicon heterojunction cell, specifically, in the N-type nc-SiO x C y A first transparent conductive layer 30 is deposited on the H film, and a second transparent conductive layer 60 is deposited on the P-type emitter layer 50. A first metal electrode 40 is formed on the first transparent conductive layer 30, and a second metal electrode 70 is formed on the second transparent conductive layer 60.

[0098] Of course, exemplary, the solar cell includes, in addition to the N-type substrate 10 and the N-type hydrogenated silicon carbide oxide film 20 formed on the light incident side of the substrate, further comprising:

[0099] A passivation contact layer formed on the backlight side of the substrate;

[0100] A passivation layer formed on the surface of the N-type hydrogenated silicon carbide oxide film and the passivation contact layer;

[0101] Metal electrodes are formed on the passivation layer on the light incident side and the backlight side.

[0102] Thus, the solar cell is a TOPCon cell. Specifically, the passivation contact layer is a tunneling oxide layer and a doped silicon layer sequentially formed on the backlight side of the substrate; x C y A first passivation layer is deposited on the H film, a second passivation layer is deposited on the doped silicon layer, a first metal electrode is formed on the first passivation layer, and a second metal electrode is formed on the second passivation layer.

[0103] Further, in this embodiment, the thickness of the N-type hydrogenated silicon carbide film 20 in the solar cell is 15nm to 30nm. Specifically, it can be 15nm, 16nm, 17nm, 20nm, 22nm, 25nm, 28nm, 30nm, etc. The thickness cannot be too thin, otherwise it may cause the series resistance to be too high, thereby reducing the fill factor FF of the battery and reducing the conductivity. The thickness cannot be too thick, otherwise the N-type hydrogenated silicon carbide film 20 absorbs more light, which is not conducive to light transmission.

[0104] like Figure 1As shown, in this embodiment, the substrate 10 includes an N-type single crystal silicon wafer 100 and a passivation layer, wherein the surface of the N-type single crystal silicon wafer 100 has a velvet structure; both the light incident surface and the backlight surface of the N-type single crystal silicon wafer 100 have a passivation layer, specifically, the light incident surface is a first passivation layer 101, and the backlight surface is a second passivation layer 102.

[0105] When the above technical solution is adopted, the N-type single crystal silicon wafer 100 with a velvet structure on the surface has a good light trapping effect and can improve the light absorption effect. The passivation layer reduces the generation of interface defects of the N-type single crystal silicon wafer 100, thereby reducing the recombination of carriers caused by defects and improving the photoelectric conversion efficiency.

[0106] Furthermore, in the present embodiment, the passivation layer is an intrinsic amorphous silicon layer, which is beneficial to improving the passivation effect of the N-type single crystal silicon wafer 100. Of course, other intrinsic silicon layers may also be used.

[0107] Furthermore, in this embodiment, the P-type back emitter layer 50 is a P-type amorphous silicon layer or a P-type microcrystalline silicon layer. Such a configuration is conducive to forming the P-type back emitter layer 50 in a low temperature environment.

[0108] like Figure 1-Figure 5 As shown, exemplary, this embodiment lists a preparation process of a solar cell:

[0109] Step 1: Texturing of 100% N-type monocrystalline silicon wafer;

[0110] Step 2: 8 nm of intrinsic amorphous silicon layer is deposited on both sides of the N-type single crystal silicon wafer 100 by PECVD method as a passivation layer to form an N-type substrate 10;

[0111] Step 3: Deposit N-type nc-SiO on the light incident surface of the substrate 10 using HWCVD x C y :H film, as the window layer of silicon heterojunction cells;

[0112] Among them, the specific steps of the third step are:

[0113] a. Before deposition, the process chamber is evacuated to a pressure of 5.0×10 -4 pa;

[0114] b. Transfer the carrier into the process chamber, introduce SiH4 with a flow rate of 300 sccm and turn on the hot wire. The hot wire temperature is 1500°C, and the process temperature in the process chamber is maintained at 250°C. A layer of amorphous silicon film is first deposited on the carrier and the inner wall of the process chamber to protect the subsequent processes from contamination;

[0115] c. Place the carrier into the preheating chamber, keep it there for 8 minutes, and then take it out;

[0116] d. placing the N-type single crystal silicon wafer 100 with a double-sided passivation layer on a carrier and transferring it into a process chamber;

[0117] e. The process chamber is evacuated to 5.0×10 -6 pa;

[0118] f. Turn on the hot wire to preheat for 50 seconds;

[0119] g. Then, SiH4 with a flow rate of 30 sccm and H2 with a flow rate of 800 sccm are introduced into the process chamber, and the hot wire is turned on. The hot wire temperature is 1900° C. and the process temperature is 250° C., which is maintained for 30 seconds to form a seed layer on the substrate 10 with a thickness of about 2 nm;

[0120] h. Then, SiH4 with a flow rate of 30 sccm, H2 with a flow rate of 800 sccm, N2O with a flow rate of 15 sccm, CH4 with a flow rate of 20 sccm, and N2 with a flow rate of 35 sccm are introduced into the process chamber, and the hot wire is turned on. The hot wire temperature is 1900°C and the process temperature is 250°C. N-type nc-SiO is deposited on one side of the N-type single crystal silicon wafer 100 with a double-sided passivation layer. x C y :H film, holding time 300s, N-type nc-SiO x C y :H film thickness is about 20nm;

[0121] i. After completion, the N-type nc-SiO x C y :H thin film silicon wafer is transferred out of the process chamber.

[0122] Step 4: Use PECVD method to plate P-type amorphous silicon or P-type microcrystalline silicon on the backlight surface as the P-type back emitter layer 50 of the silicon heterojunction battery;

[0123] Step 5: Use physical vapor deposition (PVD) to coat TCO transparent conductive layers on both sides of the battery as anti-reflection films to collect current;

[0124] Step 6: Print metal grid lines on both the upper and lower TCO transparent conductive layers as the metal electrodes of the battery to complete the production of the solar cell.

[0125] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0126] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a window layer of a solar cell, characterized in that: include: The process chamber is evacuated, and a carrier for carrying the substrate is placed in the process chamber; SiH4 is introduced into the process chamber, and a layer of amorphous silicon thin film is chemically vapor deposited on the carrier plate and the inner wall of the process chamber by using a hot wire for heating; Preheat the carrier board; Providing a substrate, and placing the substrate into the process chamber; Using silicon source gas and hydrogen source gas to form a seed layer on the first surface of the substrate by hot wire chemical vapor deposition method; An N-type hydrogenated silicon carbide film is deposited on the first surface of the substrate by a hot wire chemical vapor deposition (HWCVD) method, wherein the chemical formula of the N-type hydrogenated silicon carbide film is nc-SiO x C y :H, which is in a nanocrystalline state, wherein the non-stoichiometric ratio x is in the range of 0.1 to 0.5, the non-stoichiometric ratio y is in the range of 0.25 to 1, and the N-type hydrogenated silicon carbide film forms a window layer.

2. The method for preparing a window layer according to claim 1, characterized in that: The precursor gas for forming the N-type hydrogenated silicon oxycarbon film includes a silicon source gas, a hydrogen source gas, an oxygen source gas, a carbon source gas and a nitrogen source gas.

3. The method for preparing a window layer according to claim 2, characterized in that: The oxygen source gas includes N2O.

4. The method for preparing a window layer according to claim 2, characterized in that: The nitrogen source gas includes N2.

5. The method for preparing a window layer according to claim 1, characterized in that: Before forming the N-type hydrogenated silicon carbide film, the method further includes forming an amorphous silicon film on at least one surface of the substrate.

6. A window layer of a solar cell, characterized in that: The window layer is an N-type hydrogenated silicon carbide film, the chemical formula of the N-type hydrogenated silicon carbide film is nc-SiOxCy:H, which is in a nanocrystalline state, wherein the non-stoichiometric ratio x ranges from 0.1 to 0.5, and the non-stoichiometric ratio y ranges from 0.25 to 1; the window layer is formed by the window layer preparation method according to any one of claims 1 to 5.

7. A method for preparing a solar cell, characterized in that: The invention comprises a method for preparing a window layer as described in any one of claims 1 to 5.

8. The method for preparing a solar cell according to claim 7, characterized in that: The substrate is of N type, and further comprises the steps of: forming a P-type emitter layer on the second surface of the substrate; forming a transparent conductive layer on the surfaces of the N-type hydrogenated silicon oxycarbon film and the P-type emitter layer; and Metal electrodes are formed on the surfaces of the transparent conductive layer located on the first surface and the second surface.

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