Photovoltaic cell and preparation method thereof

Abstract

The invention provides a photovoltaic cell and a preparation method thereof. The photovoltaic cell comprises: a silicon substrate having a first surface and a second surface opposite to each other, the first surface being closer to a light-facing surface of the photovoltaic cell than the second surface; the oxide layer, the polycrystalline silicon layer and the first transparent conductive film layer are sequentially located on the first surface, the polycrystalline silicon layer has a first doping type, and the first transparent conductive film layer is located on at least part of the polycrystalline silicon layer or the whole polycrystalline silicon layer; the intrinsic layer, the doping layer and the second transparent conductive film layer are sequentially located on the second surface, and the doping layer is of a second doping type different from the first doping type. According to the photovoltaic cell and the preparation method thereof, on the premise that the passivation effect of the metal electrode region is guaranteed, parasitic absorption of light is reduced, and the cell efficiency is improved.

Description

Technical Field

[0001] The present application mainly relates to the field of photovoltaic technology, and in particular to a photovoltaic cell and a method for preparing the same. Background Art

[0002] For traditional heterojunction cells, amorphous silicon is usually used on the front of the cell, which has high parasitic absorption of light; and for traditional TOPCon cells, high temperatures are required to achieve diffusion of doping elements, which will affect the life of the silicon wafer. In addition, in conventional cells, the metal electrode needs to burn through the dielectric film thickness to contact the silicon body, and the metal electrode area is severely compounded, making it difficult to increase the opening voltage. Summary of the invention

[0003] The technical problem to be solved by the present application is to provide a photovoltaic cell and a preparation method thereof, which can reduce the parasitic absorption of light and improve the cell efficiency while ensuring the passivation effect of the metal electrode area.

[0004] To solve the above technical problems, the present application provides a photovoltaic cell, comprising: a silicon substrate having a first surface and a second surface relative to each other, the first surface being closer to the light-facing surface of the photovoltaic cell than the second surface; an oxide layer, a polycrystalline silicon layer and a first transparent conductive film layer, which are sequentially located on the first surface, wherein the polycrystalline silicon layer has a first doping type, and the first transparent conductive film layer is located on at least a portion or the entire surface of the polycrystalline silicon layer; and an intrinsic layer, a doped layer and a second transparent conductive film layer, which are sequentially located on the second surface, the doped layer has a second doping type different from the first doping type, wherein the intrinsic layer includes intrinsic amorphous silicon or intrinsic microcrystalline silicon, and the doped layer includes doped amorphous silicon or doped microcrystalline silicon.

[0005] Optionally, the photovoltaic cell further includes a plurality of first electrodes and a plurality of second electrodes, which are respectively located on the side where the first surface is located and the side where the second surface is located, wherein each first electrode is in contact with the first transparent conductive film layer, and each second electrode is in contact with the second transparent conductive film layer.

[0006] Optionally, the photovoltaic cell includes a metal contact area corresponding to the first electrode, and a non-metal contact area outside the metal contact area on one side of the first surface, wherein the oxide layer includes a first oxide layer and a second oxide layer, and the polysilicon layer includes a first polysilicon layer and a second polysilicon layer having the same first doping type, the first oxide layer and the first polysilicon layer are only located in the metal contact area, and the second oxide layer and the second polysilicon layer are simultaneously located in the metal contact area and the non-metal contact area.

[0007] Optionally, in the metal contact region, the first oxide layer, the first polysilicon layer, the second oxide layer, the second polysilicon layer and the first transparent conductive film layer are sequentially located on the first surface.

[0008] Optionally, a thickness of the first polysilicon layer along a first direction perpendicular to the silicon substrate is greater than a thickness of the second polysilicon layer along the first direction.

[0009] Optionally, a thickness of the first polysilicon layer along the first direction is greater than 100 nm, and a thickness of the second polysilicon layer along the first direction is less than 100 nm.

[0010] Optionally, a thickness of the first polysilicon layer along the first direction is between 120 nm and 130 nm, and a thickness of the second polysilicon layer along the first direction is between 40 nm and 50 nm.

[0011] Optionally, a thickness of the first polysilicon layer along the first direction is 2.5 to 3.5 times a thickness of the second polysilicon layer along the first direction.

[0012] Optionally, the photovoltaic cell also includes an anti-reflection dielectric film located only in the non-metallic contact area, and the first transparent conductive film layer is located only in the metal contact area, wherein the first transparent conductive film layer and the anti-reflection dielectric film are respectively located in the metal contact area and the non-metallic contact area, adjacent to a side of the second polysilicon layer further away from the first surface.

[0013] Optionally, the anti-reflection dielectric film includes a single layer or a composite layer, the composite layer is a plurality of layers stacked together, and the single layer or the composite layer includes one or more materials selected from silicon oxide, silicon nitride, silicon oxynitride, and magnesium fluoride.

[0014] Optionally, a width of the first transparent conductive film layer along a second direction parallel to an extending direction of the silicon substrate is greater than, equal to, or less than a width of the first electrode along the second direction.

[0015] Optionally, the polysilicon layer has a uniform thickness in a first direction perpendicular to the silicon substrate.

[0016] Optionally, the first transparent conductive film layer and / or the second transparent conductive film layer are composed of a transparent conductive oxide, and the transparent conductive oxide includes tin-doped indium oxide, tungsten-doped indium oxide and / or cesium-doped indium oxide, or includes ZnO or InO or SnO doped with one or more elements of Ga element, Sn element, Mo element, Ce element, F element, W element, and Al element.

[0017] Another aspect of the present application also proposes a method for preparing a photovoltaic cell, comprising the following steps: providing a silicon substrate, the silicon substrate having a first surface and a second surface relative to each other, the first surface being closer to the light-facing surface of the photovoltaic cell than the second surface; preparing an oxide layer, a polycrystalline silicon layer and a first transparent conductive film layer, the oxide layer, the polycrystalline silicon layer and the first transparent conductive film layer being sequentially located on the first surface, wherein the polycrystalline silicon layer has a first doping type, and the first transparent conductive film layer is located on at least a portion or the entire surface of the polycrystalline silicon layer; and preparing an intrinsic layer, a doped layer and a second transparent conductive film layer, the intrinsic layer, the doped layer and the second transparent conductive film layer being sequentially located on the second surface, the doped layer having a second doping type different from the first doping type, wherein the intrinsic layer comprises intrinsic amorphous silicon or intrinsic microcrystalline silicon, and the doped layer comprises doped amorphous silicon or doped microcrystalline silicon.

[0018] Optionally, the preparation method also includes the following steps: preparing the oxide layer and the polysilicon layer on the first surface of the silicon substrate; preparing the intrinsic layer and the doped layer on the second surface of the silicon substrate; preparing the first transparent conductive film layer and the second transparent conductive film layer on both sides; and preparing a plurality of first electrodes and a plurality of second electrodes, the plurality of first electrodes and the plurality of second electrodes being respectively located on the side where the first surface is located and the side where the second surface is located, wherein each of the first electrodes is in contact with the first transparent conductive film layer, and each of the second electrodes is in contact with the second transparent conductive film layer.

[0019] Optionally, the oxide layer includes a first oxide layer and a second oxide layer, the polysilicon layer includes a first polysilicon layer and a second polysilicon layer, and the preparation method further includes the following steps: preparing the first oxide layer and the first polysilicon layer on the first surface of the silicon substrate; setting a mask layer on the first polysilicon layer by patterning, and removing the first polysilicon layer and the first oxide layer in the area where the mask layer is not set by an alkaline solution; continuing to prepare the second oxide layer and the second polysilicon layer on one side of the first surface, wherein the thickness of the first polysilicon layer along a first direction perpendicular to the silicon substrate is greater than the thickness of the second polysilicon layer along the first direction; preparing the intrinsic layer and the doping layer on the second surface of the silicon substrate; preparing the first transparent conductive film layer and the second transparent conductive film layer on both sides; and preparing a plurality of first electrodes and a plurality of second electrodes, the plurality of first electrodes and the plurality of second electrodes are respectively located on the side where the first surface is located and the side where the second surface is located, wherein each of the first electrodes is in contact with the first transparent conductive film layer, and each of the second electrodes is in contact with the second transparent conductive film layer.

[0020] Optionally, the photovoltaic cell has a metal contact area corresponding to the first electrode on one side of the first surface, and the area outside the metal contact area is a non-metal contact area. The preparation method further includes, after preparing the multiple first electrodes and the multiple second electrodes: using an acid solution to remove the first transparent conductive film in the non-metal contact area; and preparing an anti-reflection dielectric film in the non-metal contact area.

[0021] Optionally, the silicon substrate is N-type crystalline silicon, the polysilicon layer is a phosphorus-doped polysilicon layer, and the doped layer is a boron-doped layer.

[0022] Compared with the prior art, the present application has the following advantages: the present application achieves the passivation effect and reduces the parasitic absorption of light by arranging doped polysilicon on the front of the battery, doped amorphous silicon on the back, and arranging the transparent conductive film on the front in a local or entire area. Compared with the existing battery structure, in the present application, since the electrode only needs to contact the transparent conductive film layer and does not need to burn through the dielectric layer, the electrode is prepared by using low-temperature slurry to reduce the metal composite, which is beneficial to the opening voltage; and the preparation process is short, the structure is simple, and the efficiency potential is high, which is beneficial to increase production capacity and improve yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0024] Figure 1 is a schematic structural diagram of a photovoltaic cell according to an embodiment of the present application;

[0025] Figure 2 is a schematic structural diagram of a photovoltaic cell according to another embodiment of the present application;

[0026] Figure 3 is a schematic structural diagram of a photovoltaic cell according to another embodiment of the present application; and

[0027] Figure 4 It is a schematic diagram of a process for preparing a photovoltaic cell according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0029] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0030] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0031] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0032] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0033] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0034] It should be understood that when a component is referred to as being "on another component," "connected to another component," "coupled to another component," or "contacting another component," it may be directly on, connected to, coupled to, or contacting the other component, or there may be intervening components. In contrast, when a component is referred to as being "directly on another component," "directly connected to," "directly coupled to," or "directly contacting" another component, there are no intervening components. Similarly, when a first component is referred to as being "electrically in contact with" or "electrically coupled to" a second component, there is an electrical path between the first component and the second component that allows current to flow. The electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between conductive components.

[0035] An embodiment of the present application refers to Figure 1 A photovoltaic cell 10 is proposed, which can reduce parasitic absorption of light and improve cell efficiency while ensuring the passivation effect of the metal electrode region.

[0036] according to Figure 1The photovoltaic cell 10 includes a silicon substrate 100 having a first surface 101 and a second surface 102 opposite to each other, wherein the first surface 101 is closer to the light-facing surface of the photovoltaic cell 10 than the second surface 102. Further, an oxide layer 11, a polysilicon layer 12 and a first transparent conductive film layer 13 are sequentially provided on the first surface 101, wherein the polysilicon layer 12 has a first doping type, and the first transparent conductive film layer is located on the entire polysilicon layer 12 in this embodiment. On the second surface 102, an intrinsic layer 14, a doping layer 15 and a second transparent conductive film layer 16 are sequentially provided, wherein the doping layer 15 has a second doping type different from the first doping type, that is, the doping layer 15 and the polysilicon layer 12 have opposite doping types. In this embodiment, referring to Figure 1 The polysilicon layer 12 has a uniform thickness along a first direction x perpendicular to the silicon substrate 100 , wherein the intrinsic layer 14 includes intrinsic amorphous silicon or intrinsic microcrystalline silicon, and the doped layer 15 includes doped amorphous silicon or doped microcrystalline silicon.

[0037] exist Figure 1 In the embodiment shown, a plurality of first electrodes 171 and a plurality of second electrodes 172 ( Figure 1 Only one of them is schematically shown), which are respectively located on the side where the first surface 101 is located and the side where the second surface 102 is located, wherein each first electrode 171 is in contact with the first transparent conductive film layer 13, and each second electrode 172 is in contact with the second transparent conductive film layer 16.

[0038] according to Figure 1 The photovoltaic cell 10 shown, the first surface 101 (the side close to the light-facing surface) adopts a combination of an oxide layer 11 and a polysilicon layer 12 and further combines with the first transparent conductive film layer 13, which can not only achieve a good tunneling passivation effect, but also improve the problem of high light parasitic absorption. Exemplarily, the oxide layer 11 can be made of silicon dioxide or other materials, and the thickness along the first direction x perpendicular to the silicon substrate 100 can be controlled between 1nm and 4nm. Furthermore, the silicon substrate 100 is preferably N-type doped crystalline silicon, the polysilicon layer 12 is a phosphorus-doped polysilicon layer, and the doping layer 15 is a boron-doped layer.

[0039] Further preferably, the present application includes Figure 1 In the multiple embodiments shown, the first transparent conductive film layer 13 and / or the second transparent conductive film layer 16 are composed of transparent conductive oxides, and the transparent conductive oxides include tin-doped indium oxide, tungsten-doped indium oxide and / or cesium-doped indium oxide, or ZnO or InO or SnO doped with one or more elements of Ga, Sn, Mo, Ce, F, W, and Al.

[0040] exist Figure 1 Based on the embodiment shown, Figure 2 FIG. 2 shows a schematic diagram of the structure of a photovoltaic cell 20 in another embodiment. Figure 1 Similar to the embodiment shown, the photovoltaic cell 20 includes a silicon substrate 200, and the silicon substrate 200 has a first surface 201 (closer to the light-facing surface of the photovoltaic cell 20) and a second surface 202. On one side of the second surface 202, there are an intrinsic layer 24, a doping layer 25 and a second transparent conductive film layer 26 in sequence, and the second electrode 272 is in contact with the second transparent conductive film layer 26 on the side where the second surface 202 is located. Figure 1 The photovoltaic cell 10 shown is the same as that shown in FIG. Figure 1 The embodiments are not described in detail here.

[0041] and Figure 1 The embodiment shown is different in that the photovoltaic cell 20 includes a metal contact area 2011 corresponding to the first electrode 271 (i.e., the area above the first surface 201 including the first electrode 271), and a non-metal contact area 2012 outside the metal contact area 2011 (i.e., the area above the first surface 201 not including the first electrode 271). Figure 1 The oxide layer 11 shown in this embodiment is specifically implemented as a first oxide layer 211 and a second oxide layer 212, and the polysilicon layer 12 is specifically implemented as a first polysilicon layer 221 and a second polysilicon layer 222 in this embodiment. The first polysilicon layer 221 and the second polysilicon layer 222 have the same first doping type. Figure 2 The first oxide layer 211 and the first polysilicon layer 221 are only located in the metal contact area 2011 , and the second oxide layer 212 and the second polysilicon layer 222 are simultaneously located in the metal contact area 2011 and the non-metal contact area 2012 .

[0042] For more details, see Figure 2 In the metal contact area 2011, the first oxide layer 211, the first polysilicon layer 221, the second oxide layer 212, the second polysilicon layer 222 and the first transparent conductive film layer 23 are sequentially located on the first surface 201. Through the arrangement of the stacked tunnel passivation, the passivation effect of the front side of the battery can be further improved, and a battery with better performance can be obtained.

[0043] In this embodiment, preferably, the thickness of the first polysilicon layer 221 along the first direction x perpendicular to the silicon substrate 200 is greater than the thickness of the second polysilicon layer 222 along the first direction x. Preferably, the thickness of the first polysilicon layer 221 along the first direction x is greater than 100nm, and the thickness of the second polysilicon layer 222 along the first direction x is less than 100nm. Further preferably, according to the experimental results of some embodiments of the present application, the cell efficiency is improved best when the thickness of the first polysilicon layer 221 along the first direction x is between 120nm and 130nm, and the thickness of the second polysilicon layer 222 along the first direction is between 40nm and 50nm. In addition, when the thickness of the first polysilicon layer 221 along the first direction x is set to 2.5 to 3.5 times the thickness of the second doped polysilicon layer 222 along the first direction x, the effect of improving the cell efficiency tends to be stable, and a cell efficiency improvement effect of 0.1% can be achieved.

[0044] More preferably, Figure 2 Based on the embodiment shown, Figure 3 A photovoltaic cell 30 is shown and provides a Figure 2 A preferred variation of the photovoltaic cell 20 is shown, and therefore the same parts are marked with the same reference numerals. Figure 3 The photovoltaic cell 30 further includes an anti-reflection dielectric film 28 located only in the non-metallic contact area 2012, and the first transparent conductive film layer 23 is different from Figure 2 The entire surface of the embodiment shown is paved in this embodiment only in the metal contact area 2011. Figure 3 The first transparent conductive film layer 23 and the anti-reflection dielectric film 28 are respectively located in the metal contact area 2011 and the non-metal contact area 2012 and are adjacent to the side of the second polysilicon layer 222 that is further away from the first surface 201 .

[0045] Exemplarily, the anti-reflection dielectric film 28 includes a single layer or a composite layer, the composite layer is a multi-layer stack, and the single layer or the composite layer includes one or more materials selected from silicon oxide, silicon nitride, silicon oxynitride, and magnesium fluoride. It should be noted that even for the same material, such as silicon nitride, a multi-layer stacked structure with different refractive indices can be formed. Therefore, whether it is a single layer or a multi-layer stacked composite layer, it also includes a combination of one or more of the above materials. In this embodiment, the width of the first transparent conductive film layer 23 along the second direction y parallel to the extension direction of the silicon substrate 200 is greater than, equal to, or less than the width of the first electrode 271 along the second direction y. In this embodiment, Figure 2 On the basis of the illustrated embodiment, the first transparent conductive film layer 23 in the non-metallic contact area 2012 is replaced with an anti-reflection dielectric film 28, which further reduces the parasitic absorption of the non-metallic contact area 2012 on the light side of the cell, which is beneficial to further improve the current and conversion efficiency.

[0046] Another aspect of this application refers to Figure 4 A method 40 for preparing a photovoltaic cell is proposed, which can reduce the parasitic absorption of light and improve the efficiency of the cell while ensuring the passivation effect of the metal electrode region. Figure 4 Flowcharts are used to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Instead, various steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0047] according to Figure 4 , the preparation method 40 includes the following steps.

[0048] Step 41 is to provide a silicon substrate, wherein the silicon substrate has a first surface and a second surface opposite to each other, wherein the first surface is closer to the light-facing surface of the photovoltaic cell than the second surface;

[0049] Step 42 is to prepare an oxide layer, a polysilicon layer and a first transparent conductive film layer, wherein the oxide layer, the polysilicon layer and the first transparent conductive film layer are sequentially located on the first surface, wherein the polysilicon layer has a first doping type, and the first transparent conductive film layer is located on at least a portion or the entire polysilicon layer.

[0050] Step 43 is to prepare an intrinsic layer, a doped layer and a second transparent conductive film layer, wherein the intrinsic layer, the doped layer and the second transparent conductive film layer are sequentially located on the second surface, and the doped layer has a second doping type different from the first doping type.

[0051] In the embodiments of the preparation method proposed in the present application, the silicon substrate is preferably N-type crystalline silicon, the polysilicon layers are all phosphorus-doped polysilicon layers, and the doped layers are boron-doped layers. Exemplarily, the preparation method 40 can be used to prepare the above-mentioned Figure 1 to Figure 3 The photovoltaic cells 10 to 30 shown are taken as an example to further illustrate the details of the preferred embodiment based on the preparation method 40.

[0052] First, refer to Figure 1 , when the preparation method 40 is used to prepare Figure 1When the photovoltaic cell 10 is shown, the preparation method 40 can be specifically implemented as the following steps. First, an oxide layer 11 and a polysilicon layer 12 are prepared on the first surface 101 of the silicon substrate 100. Then, an intrinsic layer 15 and a doping layer 16 are prepared on the second surface 102 of the silicon substrate 100. On this basis, a first transparent conductive film layer 13 and a second transparent conductive film layer 16 are prepared on both sides. Finally, a plurality of first electrodes 171 and a plurality of second electrodes 172 are prepared on both sides, respectively, and the plurality of first electrodes 171 and the plurality of second electrodes 172 are respectively located on the side where the first surface 101 is located and the side where the second surface 102 is located, wherein each first electrode 171 is in contact with the first transparent conductive film layer 13, and each second electrode 172 is in contact with the second transparent conductive film layer 16.

[0053] On this basis, for Figure 2 In the embodiment shown, the oxide layer includes a first oxide layer 211 and a second oxide layer 212, and the polysilicon layer includes a first polysilicon layer 221 and a second polysilicon layer 222. The preparation method 40 can be specifically implemented as follows. First, a first oxide layer 211 and a first polysilicon layer 221 are prepared on the first surface 201 of the silicon substrate 200. Then, a mask layer is graphically set on the first polysilicon layer 221, and the first polysilicon layer 221 and the first oxide layer 211 in the area where the mask layer is not set are removed by an alkaline solution. It can be understood that the area where the mask layer is set corresponds to the metal contact area 2011 after the photovoltaic cell 20 is prepared, and the area where the mask layer is not set corresponds to the non-metal contact area 2012 after the photovoltaic cell 20 is prepared. On this basis, a second oxide layer 212 and a second polysilicon layer 222 are further prepared on one side of the first surface 201 , wherein the thickness of the first polysilicon layer 221 along the first direction x perpendicular to the silicon substrate 200 is greater than the thickness of the second polysilicon layer 222 along the first direction x.

[0054] Furthermore, an intrinsic layer 24 and a doping layer 25 are prepared on the second surface 202 of the silicon substrate 200. Then, a first transparent conductive film layer 23 and a second transparent conductive film layer 26 are prepared on both sides. Finally, a plurality of first electrodes 271 and a plurality of second electrodes 272 are prepared, and the plurality of first electrodes 271 and the plurality of second electrodes 272 are respectively located on the side where the first surface 201 is located and the side where the second surface 202 is located, wherein each first electrode 271 is in contact with the first transparent conductive film layer 23, and each second electrode 272 is in contact with the second transparent conductive film layer 26.

[0055] On this basis, in order to prepare Figure 3The preparation method of the photovoltaic cell 30 shown may further include first removing the first transparent conductive film 23 in the non-metallic contact area 2012 using an acid solution after preparing a plurality of first electrodes 271 and a plurality of second electrodes 272 , and further preparing an anti-reflection dielectric film 28 in the non-metallic contact area 2012 .

[0056] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0057] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0058] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0059] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0060] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A photovoltaic cell, characterized in that: include: A silicon substrate having a first surface and a second surface opposite to each other, wherein the first surface is closer to a light-facing surface of the photovoltaic cell than the second surface; an oxide layer, a polysilicon layer, and a first transparent conductive film layer, which are sequentially disposed on the first surface, wherein the polysilicon layer has a first doping type, and the first transparent conductive film layer is disposed on at least a portion or the entire surface of the polysilicon layer; and An intrinsic layer, a doped layer and a second transparent conductive film layer are sequentially located on the second surface, the doped layer has a second doping type different from the first doping type, wherein the intrinsic layer includes intrinsic amorphous silicon or intrinsic microcrystalline silicon, and the doped layer includes doped amorphous silicon or doped microcrystalline silicon.

2. The photovoltaic cell according to claim 1, characterized in that It also includes a plurality of first electrodes and a plurality of second electrodes, which are respectively located on the side where the first surface is located and the side where the second surface is located, wherein each of the first electrodes is in contact with the first transparent conductive film layer, and each of the second electrodes is in contact with the second transparent conductive film layer.

3. The photovoltaic cell according to claim 2, characterized in that: The photovoltaic cell includes a metal contact area corresponding to the first electrode and a non-metal contact area outside the metal contact area on one side of the first surface, wherein the oxide layer includes a first oxide layer and a second oxide layer, and the polysilicon layer includes a first polysilicon layer and a second polysilicon layer having the same first doping type, the first oxide layer and the first polysilicon layer are only located in the metal contact area, and the second oxide layer and the second polysilicon layer are simultaneously located in the metal contact area and the non-metal contact area.

4. The photovoltaic cell according to claim 3, characterized in that: In the metal contact region, the first oxide layer, the first polysilicon layer, the second oxide layer, the second polysilicon layer, and the first transparent conductive film layer are sequentially located on the first surface.

5. The photovoltaic cell according to claim 4, characterized in that A thickness of the first polysilicon layer along a first direction perpendicular to the silicon substrate is greater than a thickness of the second polysilicon layer along the first direction.

6. The photovoltaic cell according to claim 5, characterized in that: The thickness of the first polysilicon layer along the first direction is greater than 100 nm, and the thickness of the second polysilicon layer along the first direction is less than 100 nm.

7. The photovoltaic cell according to claim 6, characterized in that: The thickness of the first polysilicon layer along the first direction is between 120 nm and 130 nm, and the thickness of the second polysilicon layer along the first direction is between 40 nm and 50 nm.

8. The photovoltaic cell according to claim 6, characterized in that: The thickness of the first polysilicon layer along the first direction is 2.5 to 3.5 times the thickness of the second polysilicon layer along the first direction.

9. The photovoltaic cell according to any one of claims 3 to 8, characterized in that: It also includes an anti-reflection dielectric film located only in the non-metallic contact area, and the first transparent conductive film layer is located only in the metal contact area, wherein the first transparent conductive film layer and the anti-reflection dielectric film are respectively located in the metal contact area and the non-metallic contact area, adjacent to the side of the second polysilicon layer farther away from the first surface.

10. The photovoltaic cell according to claim 9, characterized in that The anti-reflection dielectric film includes a single layer or a composite layer, the composite layer is a plurality of layers stacked together, and the single layer or the composite layer includes one or more materials selected from silicon oxide, silicon nitride, silicon oxynitride, and magnesium fluoride.

11. The photovoltaic cell according to claim 9, characterized in that: The width of the first transparent conductive film layer along a second direction parallel to the extending direction of the silicon substrate is greater than, equal to, or less than the width of the first electrode along the second direction.

12. The photovoltaic cell according to claim 1, characterized in that: The polysilicon layer has a uniform thickness in a first direction perpendicular to the silicon substrate.

13. The photovoltaic cell according to claim 1, characterized in that: The first transparent conductive film layer and / or the second transparent conductive film layer are composed of a transparent conductive oxide, and the transparent conductive oxide includes tin-doped indium oxide, tungsten-doped indium oxide and / or cesium-doped indium oxide, or ZnO or InO or SnO doped with one or more elements of Ga, Sn, Mo, Ce, F, W, and Al.

14. A method for preparing a photovoltaic cell, characterized in that: The steps include: Providing a silicon substrate, wherein the silicon substrate has a first surface and a second surface opposite to each other, wherein the first surface is closer to a light-facing surface of the photovoltaic cell than the second surface; preparing an oxide layer, a polysilicon layer and a first transparent conductive film layer, wherein the oxide layer, the polysilicon layer and the first transparent conductive film layer are sequentially disposed on the first surface, wherein the polysilicon layer has a first doping type, and the first transparent conductive film layer is disposed on at least a portion or the entire surface of the polysilicon layer; and An intrinsic layer, a doped layer and a second transparent conductive film layer are prepared, wherein the intrinsic layer, the doped layer and the second transparent conductive film layer are sequentially located on the second surface, and the doped layer has a second doping type different from the first doping type, wherein the intrinsic layer includes intrinsic amorphous silicon or intrinsic microcrystalline silicon, and the doped layer includes doped amorphous silicon or doped microcrystalline silicon.

15. The preparation method according to claim 14, characterized in that: The following steps are also included: Prepare the oxide layer and the polysilicon layer on the first surface of the silicon substrate; Prepare the intrinsic layer and the doping layer on the second surface of the silicon substrate; preparing the first transparent conductive film layer and the second transparent conductive film layer on both sides; as well as A plurality of first electrodes and a plurality of second electrodes are prepared, wherein the plurality of first electrodes and the plurality of second electrodes are respectively located on the side where the first surface is located and the side where the second surface is located, wherein each of the first electrodes is in contact with the first transparent conductive film layer, and each of the second electrodes is in contact with the second transparent conductive film layer.

16. The preparation method according to claim 14, characterized in that: The oxide layer includes a first oxide layer and a second oxide layer, the polysilicon layer includes a first polysilicon layer and a second polysilicon layer, and the preparation method further includes the following steps: Prepare the first oxide layer and the first polysilicon layer on the first surface of the silicon substrate; Setting a mask layer on the first polysilicon layer by patterning, and removing the first polysilicon layer and the first oxide layer in the area where the mask layer is not set by using an alkaline solution; Continue to prepare the second oxide layer and the second polysilicon layer on one side of the first surface, wherein the thickness of the first polysilicon layer along a first direction perpendicular to the silicon substrate is greater than the thickness of the second polysilicon layer along the first direction; Prepare the intrinsic layer and the doping layer on the second surface of the silicon substrate; preparing the first transparent conductive film layer and the second transparent conductive film layer on both sides; and A plurality of first electrodes and a plurality of second electrodes are prepared, wherein the plurality of first electrodes and the plurality of second electrodes are respectively located on the side where the first surface is located and the side where the second surface is located, wherein each of the first electrodes is in contact with the first transparent conductive film layer, and each of the second electrodes is in contact with the second transparent conductive film layer.

17. The preparation method according to claim 15, characterized in that: The photovoltaic cell has a metal contact area corresponding to the first electrode on one side of the first surface, and a non-metal contact area outside the metal contact area. The preparation method further comprises, after preparing the plurality of first electrodes and the plurality of second electrodes: Using an acid solution to remove the first transparent conductive film in the non-metal contact area; and An anti-reflection dielectric film is prepared in the non-metallic contact area.

18. The preparation method according to any one of claims 14 to 17, characterized in that: The silicon substrate is N-type crystalline silicon, the polysilicon layer is a phosphorus-doped polysilicon layer, and the doped layer is a boron-doped layer.

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