Solar cell
By introducing a zinc oxide transparent conductive layer and optimizing the electrode contact structure in solar cells, the problems of low carrier lateral transport performance and low conversion efficiency were solved, resulting in higher cell efficiency.
Patent Information
- Application Number
- CN202422672319.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-11-01
AI Technical Summary
There is room for improvement in the lateral carrier transport performance and cell conversion efficiency of existing TOPcon solar cells.
A structural design that combines a transparent conductive layer containing zinc oxide with a tunneling oxide layer and a doped polycrystalline silicon layer enhances the lateral transport performance of charge carriers and improves the battery conversion efficiency by optimizing the contact method between the electrode and the transparent conductive layer.
This improves the lateral transport performance of charge carriers, enhances the passivation effect of solar cells, and thus improves the conversion efficiency of the cells.
Smart Images
Figure CN223528429U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application mainly relates to the field of photovoltaic technology, and in particular to a solar cell. BACKGROUND
[0002] TOPcon (Tunnel Oxide Passivated Contact) solar cell is one of the important types of solar cells. The TOPcon solar cell forms a tunnel oxide passivation contact structure by forming an ultra-thin oxide layer and a doped polysilicon layer. This structure not only significantly reduces the back surface recombination, but also realizes higher carrier collection efficiency through an optimized doping process. However, the pursuit of higher cell efficiency is a continuous pursuit in the field. CONTENT OF THE UTILITY MODEL
[0003] The technical problem to be solved by the present application is to provide a solar cell which can enhance the carrier lateral transport performance and improve the conversion efficiency of the cell.
[0004] To solve the above technical problem, the present application provides a solar cell, comprising: a silicon substrate having opposite first and second surfaces, the first surface comprising alternating first and second regions; a first tunnel oxide layer and a first doped polysilicon layer stacked on the first region; a first transparent conductive layer disposed on the second region, the first transparent conductive layer comprising zinc oxide; a second tunnel oxide layer and a second doped polysilicon layer stacked on the second surface; and a first electrode electrically connected to the first doped polysilicon layer and a second electrode electrically connected to the second doped polysilicon layer.
[0005] In an embodiment of the present application, the first transparent conductive layer is in contact with the side surface of the first tunnel oxide layer and the side surface of the first doped polysilicon layer.
[0006] In an embodiment of the present application, the first electrode is in contact with the first doped polysilicon layer through the first transparent conductive layer.
[0007] In an embodiment of the present application, the first transparent conductive layer is in contact with the surface of the first doped polysilicon layer away from the silicon substrate.
[0008] In an embodiment of the present application, the first electrode is in contact with the first transparent conductive layer, and part of the first transparent conductive layer is located between the first electrode and the first doped polysilicon layer in the thickness direction of the silicon substrate.
[0009] In an embodiment of the present application, a second transparent conductive layer is further included, disposed on the surface of the second doped polysilicon layer away from the silicon substrate.
[0010] In an embodiment of the present application, the second electrode is in contact with the second transparent conductive layer.
[0011] In an embodiment of the present application, the zinc oxide is doped with aluminum atoms, and the doping concentration of the aluminum atoms is 1E20cm -3 ~1E21cm -3 .
[0012] In an embodiment of the present application, the first electrode comprises a first seed layer and a first plating layer, and / or the second electrode comprises a second seed layer and a second plating layer.
[0013] In an embodiment of the present application, the solar cell further comprises a first dielectric layer disposed on the first transparent conductive layer, wherein the first electrode is in contact with the first transparent conductive layer through the first dielectric layer.
[0014] Compared with the prior art, the present application has the following advantages: the first transparent conductive layer containing zinc oxide has a higher carrier mobility, which can strengthen the carrier lateral transmission performance. In addition, the first transparent conductive layer containing zinc oxide has a better passivation effect, which can improve the conversion efficiency of the cell. BRIEF DESCRIPTION OF DRAWINGS
[0015] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute apart of this application, illustrate embodiments of the present application, and together with the description serve to explain the principles of the present application. In the drawings:
[0016] Figure 1 is a structural schematic diagram of a solar cell in an embodiment of the present application;
[0017] Figure 2 is a structural schematic diagram of a solar cell in another embodiment of the present application.
[0018] REFERENCE NUMERALS
[0019] Silicon substrate 110 First transparent conductive layer 140 Second seed layer 181
[0020] First surface 111 Second tunneling oxide layer 150 Second plating layer 182
[0021] Second surface 112 Second doped polysilicon layer 160 Second transparent conductive layer 190
[0022] First region 111a First electrode 170 First dielectric layer 210
[0023] Second region 111b First seed layer 171 Second dielectric layer 220
[0024] first tunneling oxide layer 120 first plated layer 172
[0025] first doped polysilicon layer 130 second electrode 180 DETAILED DESCRIPTION
[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and for those skilled in the art, the present application can also be applied to other similar scenarios without creative labor on the basis of the drawings. Unless it is clear from the language context or otherwise indicated, the same reference numbers in the drawings represent the same structures or operations.
[0027] As shown in the present application and claims, unless the context clearly indicates otherwise, the words "one", "an", "a", and / or "the" do not specify a singular form but can include a plural form as well. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements.
[0028] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the various embodiments described herein are not limitations on the scope of the present application. At the same time, it should be understood that the sizes of the various parts shown in the drawings are not drawn in accordance with the actual proportional relationship. The technology, methods and devices known to those skilled in the relevant art can not be discussed in detail, but under appropriate circumstances, the technology, methods and devices should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.
[0029] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and in the absence of contrary indications, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer relative to the contour of the parts themselves.
[0030] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.
[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.
[0032] The solar cell of this application will now be described through examples.
[0033] refer to Figure 1 The diagram shows a cross-sectional view of a solar cell in one embodiment. The solar cell in this embodiment includes a silicon substrate 110, a first tunneling oxide layer 120, a first doped polycrystalline silicon layer 130, a first transparent conductive layer 140, a second tunneling oxide layer 150, a second doped polycrystalline silicon layer 160, a first electrode 170, and a second electrode 180.
[0034] Specifically, the silicon substrate 110 has opposing first surfaces 111 and second surfaces 112. When the solar cell is operating, the first surface 111 faces the sun, and the first surface 111 and / or the second surface 112 may have a pyramidal textured surface. The first surface 111 includes alternating first regions 111a and second regions 111b. The silicon substrate 110 may be N-type or P-type doped monocrystalline silicon.
[0035] A first tunneling oxide layer 120 is disposed on the first region 111a, and a first doped polycrystalline silicon layer 130 is disposed on the surface of the first tunneling oxide layer 120 facing away from the silicon substrate 110. The first tunneling oxide layer 120 may include silicon oxide (SiOx). The first doped polycrystalline silicon layer 130 may be p-type or n-type doped; more specifically, the first doped polycrystalline silicon layer 130 may include n-type or p-type doped polycrystalline silicon. The first tunneling oxide layer 120 and the first doped polycrystalline silicon layer 130 have a passivation effect on the solar cell.
[0036] A first transparent conductive layer 140 is disposed on the second region 111b, and the first transparent conductive layer 140 comprises zinc oxide (ZnO). In one embodiment, the zinc oxide is doped with aluminum atoms at a doping concentration of 1E20cm⁻¹. -3 ~1E21cm -3 Any value within the range, for example, a doping concentration of 1E20cm. -3 2E20cm -3 3E20cm -3 4E20cm -3 5E20cm -3 6E20cm -3 7E20cm -3 8E20cm -3 9E20cm -3 Or 2E21cm -3 The aluminum atoms within the aforementioned doping concentration range enable the first transparent conductive layer 140 to exhibit excellent field passivation effects for the solar cell. Furthermore, zinc oxide possesses high carrier mobility, thus enhancing the lateral carrier transport performance.
[0037] like Figure 1 As shown, the first transparent conductive layer 140 is in contact with the side surface of the first tunneling oxide layer 120 and the side surface of the first doped polysilicon layer 130. The first electrode 170 passes through the first transparent conductive layer 140 and contacts the first doped polysilicon layer 130.
[0038] refer to Figure 2 As shown, in another embodiment, in addition to the sides of the first tunneling oxide layer 120 and the first doped polysilicon layer 130, the first transparent conductive layer 140 also contacts the surface of the first doped polysilicon layer 130 away from the silicon substrate 110. The first electrode 170 contacts the first transparent conductive layer 140, and a portion of the first transparent conductive layer is located between the first electrode 170 and the first doped polysilicon layer 130 in the thickness direction D1 of the silicon substrate 110. The first transparent conductive layer located on the surface of the first doped polysilicon layer 130 away from the silicon substrate 110 can passivate the first doped polysilicon layer 130, thereby improving the passivation effect on the solar cell.
[0039] BackFigure 1 As shown, a second tunneling oxide layer 150 is disposed on the second surface 112, the second tunneling oxide layer 150 is in direct contact with the second surface 112, and the second tunneling oxide layer 150 can include silicon oxide. A second doped polysilicon layer 160 is disposed on a surface of the second tunneling oxide layer 150 facing away from the silicon substrate 110. The second doped polysilicon layer 160 can be N-type or P-type doped, and more specifically, the second doped polysilicon layer 160 can include N-type or P-type doped polysilicon, the doping type of the first doped polysilicon layer 130 is opposite to the doping type of the second doped polysilicon layer 160, and when the second doped polysilicon layer 160 is P-type doped, the doping element can be gallium (Ga). The second tunneling oxide layer 150 and the second doped polysilicon layer 160 have a passivation effect on the solar cell.
[0040] The first electrode 170 is electrically connected to the first doped polysilicon layer 130. Specifically, as shown in FIG. 1A, the first electrode 170 can be electrically connected to the first doped polysilicon layer 130 by directly contacting the first doped polysilicon layer 130, and as shown in FIG. 1B, the first electrode 170 can be electrically connected to the first doped polysilicon layer 130 by directly contacting the first transparent conductive layer 140 without directly contacting the first doped polysilicon layer 130. Figure 1 Figure 2
[0041] In an embodiment, the first electrode 170 can be prepared using an electroplating process. In the case where the first electrode 170 is prepared using the electroplating process, the first electrode 170 includes a first seed layer 171 and a first electroplated layer 172, the first seed layer 171 can include copper, and the first electroplated layer 172 can include copper and tin, for example, the first electroplated layer 172 includes a layer of copper and a layer of tin covering the copper. In other embodiments, the first electrode 170 can also be prepared using a screen printing process.
[0042] The second electroplated layer 182 is electrically connected to the second doped polysilicon layer 160, and the second electrode 180 can be electrically connected to the second doped polysilicon layer 160 by directly contacting the second doped polysilicon layer 160. In an embodiment, the second electrode 180 can be prepared using an electroplating process. In the case where the second electrode 180 is prepared using the electroplating process, the second electrode 180 includes a second seed layer 181 and a second electroplated layer 182, the second seed layer 181 can include copper, and the second electroplated layer 182 can include copper and tin, for example, the second electroplated layer 182 includes a layer of copper and a layer of tin covering the copper. In other embodiments, the second electroplated layer 182 can also be prepared using a screen printing process.
[0043] Figure 1 As shown, in one embodiment, the solar cell further comprises a second transparent conductive layer 190 disposed on the surface of the second doped polysilicon layer 160 facing away from the silicon substrate 110. The second electrode 180 is in contact with the second transparent conductive layer 190, and the second electrode 180 is electrically connected to the second doped polysilicon layer 160 through the second transparent conductive layer 190.
[0044] In one embodiment, the solar cell further comprises a first dielectric layer 210 disposed on the first transparent conductive layer 140, and the first electrode 170 is in contact with the first transparent conductive layer 140 through the first dielectric layer 210. The first dielectric layer 210 can comprise silicon nitride (SiNx), and the first dielectric layer 210 has passivation (e.g. hydrogen passivation) and anti-reflective effects.
[0045] In one embodiment, the solar cell further comprises a second dielectric layer 220 disposed on the surface of the second transparent conductive layer 190 facing away from the silicon substrate 110, and the second electrode 180 is in contact with the second transparent conductive layer 190 through the second dielectric layer 220.
[0046] To help more clearly understand the present application, a method for preparing the solar cell of the present application is given below, which comprises the following steps:
[0047] Step 1: providing an N-type silicon substrate having opposite front and back surfaces, the front surface facing the sun when the solar cell is in operation;
[0048] Step 2: preparing a back surface tunneling oxide layer and a gallium-doped P-type polysilicon layer on the back surface of the N-type silicon substrate;
[0049] Step 3: preparing a front surface local tunneling oxide layer and an N-type polysilicon layer on the front surface of the N-type silicon substrate;
[0050] Step 4: preparing a layer of ZnO as a front surface transparent conductive layer;
[0051] Step 5: preparing a back surface transparent conductive layer (this step can also be omitted);
[0052] Step 6: preparing a front and back surface silicon nitride layer;
[0053] Step 7: preparing a front and back surface local seed layer, the seed layer being copper;
[0054] Step 8: preparing a copper-tin composite electroplating layer on the seed layer by an electroplating process.
[0055] Having described the basic concepts, it is obvious that the above-described application disclosure is merely an example for the skilled person in the art and does not limit the application. Although not explicitly described herein, the skilled person can make various modifications, improvements and modifications to the application. Such modifications, improvements and modifications are suggested in the application and still fall within the spirit and scope of the exemplary embodiments of the application.
[0056] Meanwhile, specific words are used in the application to describe the embodiments of the application. As "one embodiment", "an embodiment", and / or "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that the "an embodiment" or "one embodiment" or "an alternative embodiment" mentioned in different places in the specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of the application can be properly combined.
[0057] Similarly, it should be noted that, in order to simplify the description of the application and to help understand one or more embodiments of the application, sometimes multiple features are combined into one embodiment, figure or description thereof in the foregoing description of the embodiments of the application. However, this method of disclosure does not mean that the features required by the application are more than those mentioned in the claims. In fact, the features of the embodiments are less than all the features disclosed in the foregoing single embodiment.
[0058] Some embodiments use numbers to describe components, attributes, etc. It should be understood that such numbers used in the description of the embodiments are, in some examples, modified by the adjectives "about", "approximately" or "generally". Unless otherwise stated, "about", "approximately" or "generally" indicates that the number allows for a ±20% variation. Accordingly, in some embodiments, the numerical parameters in the specification and claims are approximations that can vary depending on the desired properties of the individual embodiments. In some embodiments, numerical parameters should be considered in the context of the number of significant digits and errors inherent to measurement using conventional measurement equipment. Although the numerical ranges and parameters in some embodiments of the application are approximations, in specific embodiments, these numerical values are set to be as precise as possible.
[0059] Although the application has been described with reference to the current specific embodiments, those skilled in the art will realize that the above-described embodiments are only used to illustrate the application, and various equivalent changes or replacements can be made without departing from the spirit of the application, therefore, any changes, modifications to the above-described embodiments within the scope of the spirit of the application will fall within the scope of the claims of the application.
Claims
1. A solar cell, characterized by, Comprise: a silicon substrate having opposite first and second surfaces, the first surface comprising first and second regions which alternate; a first tunneling oxide layer and a first doped polysilicon layer which are stacked on the first regions; a first transparent conductive layer which is disposed on the second regions, the first transparent conductive layer comprising zinc oxide; a second tunneling oxide layer and a second doped polysilicon layer which are stacked on the second surface; and a first electrode which is electrically connected to the first doped polysilicon layer, and a second electrode which is electrically connected to the second doped polysilicon layer. The first transparent conductive layer is in contact with the side surface of the first tunneling oxide layer and the side surface of the first doped polysilicon layer.
2. The solar cell of claim 1, wherein, The first electrode is in contact with the first doped polysilicon layer through the first transparent conductive layer.
3. The solar cell of claim 2, wherein the first and second doped regions are formed by implanting dopants into the first and second surfaces of the substrate. The first transparent conductive layer is in contact with the surface of the first doped polysilicon layer which faces away from the silicon substrate.
4. The solar cell of claim 2, wherein the first and second doped regions are formed by implanting dopants into the first and second surfaces of the substrate. The first electrode is in contact with the first transparent conductive layer, and part of the first transparent conductive layer is located between the first electrode and the first doped polysilicon layer in the thickness direction of the silicon substrate.
5. The solar cell of claim 4, wherein the first and second doped regions are formed by implanting dopants into the first and second surfaces of the substrate. Further comprising a second transparent conductive layer which is disposed on the surface of the second doped polysilicon layer which faces away from the silicon substrate.
6. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof. The second electrode is in contact with the second transparent conductive layer.
7. The solar cell of claim 6, wherein the first and second doped regions are formed by implanting dopants into the first and second surfaces of the substrate. Aluminum atoms are doped in the zinc oxide.
8. The solar cell of claim 1, wherein, The first electrode comprises a first seed layer and a first electroplated layer, and / or the second electrode comprises a second seed layer and a second electroplated layer.
9. The solar cell of claim 1, wherein, Further comprising a first dielectric layer which is disposed on the first transparent conductive layer, wherein the first electrode is in contact with the first transparent conductive layer through the first dielectric layer.
10. The solar cell of claim 1, wherein the first and second electrodes are formed of a material selected from the group consisting of silver, aluminum, gold, copper, and combinations thereof.