All-back junction cell, preparation method thereof and laminated cell

Abstract

The invention provides an all-back-junction cell and a preparation method thereof, and a laminated cell. The all-back-junction cell comprises a cell substrate; the first electrode and the second electrode are positioned on the back surface of the battery substrate; the passivation contact structure is positioned on the front surface, opposite to the back surface, of the battery substrate; and the third electrode is positioned on one side, deviating from the battery substrate, of the passivation contact structure.

Description

[0001] This application is a divisional application filed for the application with the application number: 202310406529.2 (invention creation name: all-back contact battery and its preparation method, application date: April 17, 2023). Technical Field

[0002] This application relates to the technical field of batteries, and particularly relates to an all-back contact battery, its preparation method, and a stacked battery. Background Art

[0003] In recent years, the application market of solar cells has developed rapidly, with broad and diverse application scenarios. Under this general background, the market has put forward more requirements for solar cells, including the development needs of diversified battery technologies and the facilitation of battery product use. Summary of the Invention

[0004] This application provides an all-back contact battery, its preparation method, and a stacked battery.

[0005] In a first aspect, this application provides an all-back contact battery, which includes: a battery substrate; a first electrode and a second electrode located on the back surface of the battery substrate; a passivated contact structure located on the front surface of the battery substrate opposite to the back surface; and a third electrode located on a side of the passivated contact structure away from the battery substrate.

[0006] In some embodiments, the passivated contact structure includes a tunneling oxide layer and a polysilicon layer; the tunneling oxide layer is located on the front surface of the battery substrate opposite to the back surface; the polysilicon layer is located on a side of the tunneling oxide layer away from the battery substrate; and the third electrode is located on a side of the polysilicon layer away from the battery substrate.

[0007] In some embodiments, the polysilicon layer is doped with phosphorus or boron.

[0008] In some embodiments, the third electrode is a transparent conductive structure.

[0009] In some embodiments, the material of the transparent conductive structure includes one or more of indium tin oxide and zinc oxide.

[0010] In some embodiments, the first electrode is a positive electrode, and an emitter is further provided between the first electrode and the back surface of the battery substrate.

[0011] In some embodiments, the second electrode is a negative electrode, and a back surface field structure is further provided between the second electrode and the back surface of the battery substrate.

[0012] In some embodiments, the thickness range of the tunneling oxide layer is from 1 nanometer to 2 nanometers.

[0013] In some embodiments, the thickness of the polysilicon layer ranges from 1 nanometer to 1000 nanometers.

[0014] In some embodiments, the thickness of the third electrode ranges from 1 nanometer to 1000 nanometers.

[0015] In a second aspect, the present application provides a method for manufacturing a full-back-contact cell, the manufacturing method comprising: providing a cell substrate having a front surface and a back surface opposite to the front surface; forming a passivated contact structure on the front surface of the cell substrate; forming a third electrode on a side of the passivated contact structure facing away from the cell substrate; and forming a first electrode and a second electrode on the back surface of the cell substrate.

[0016] In some embodiments, the passivated contact structure includes a tunneling oxide layer and a polysilicon layer; the forming of the passivated contact structure on the front surface of the cell substrate includes: forming a tunneling oxide layer on the front surface of the cell substrate; and forming a polysilicon layer on a side of the tunneling oxide layer facing away from the cell substrate, and the third electrode is formed on a side of the polysilicon layer facing away from the cell substrate.

[0017] In some embodiments, before forming the first electrode and the second electrode on the back surface of the cell substrate, the manufacturing method further includes: forming an emitter and a back surface field structure on the back surface of the cell substrate; forming a passivation film on a surface of the emitter and the back surface field structure facing away from the cell substrate; performing a patterning process on the passivation film to form a first via corresponding to the emitter and a second via corresponding to the back surface field structure; and forming the first electrode and the second electrode on the back surface of the cell substrate, including: forming the first electrode in the first via, and the first electrode is connected to the emitter through the first via; and forming the second electrode in the second via, and the second electrode is connected to the back surface field structure through the second via.

[0018] The technical solution of the full-back-contact cell and its manufacturing method provided by the present application, by disposing the first electrode and the second electrode of the full-back-contact cell on the back surface of the cell substrate, and simultaneously disposing a third electrode on the front surface of the cell substrate, the third electrode can provide an electrical connection port on the front surface of the full-back-contact cell, can be used to form a stacked cell in series with other cells, is conducive to applying the full-back-contact cell to the manufacture of stacked cells, and a passivated contact structure is also disposed on the front surface of the cell substrate, and the passivated contact structure can provide good surface passivation for the front surface of the cell substrate, and can effectively reduce surface recombination and metal contact recombination.

[0019] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application, and do not constitute a limitation to the present application. By describing the detailed exemplary embodiments with reference to the accompanying drawings, the above and other features and advantages will become more apparent to those skilled in the art. In the drawings:

[0021] Figure 1 FIG. is a schematic structural diagram of a full-back contact battery provided by an embodiment of the present application;

[0022] Figure 2 FIG. is a schematic flow diagram of a method for manufacturing a full-back contact battery provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To enable those skilled in the art to better understand the technical solutions of the present application, the following provides a description of exemplary embodiments of the present application with reference to the accompanying drawings. Various details of the embodiments of the present application are included to assist in understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for clarity and conciseness, the description below omits the description of well-known functions and structures.

[0024] Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0025] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. As used herein, the singular forms "a" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms "comprises" and / or "consists of" are used in this specification, the specified features, wholes, steps, operations, elements, and / or components are present, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof. "Connected" or "coupled" and other similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0027] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant art and the context of the present application, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0028] Figure 1 The figure is a schematic structural diagram of a full-back-contact battery provided for the embodiments of the present application. The embodiments of the present application provide a full-back-contact battery. Referring to Figure 1 , the battery 10 includes a battery substrate 11, a first electrode 12, a second electrode 13, a passivated contact structure 14, and a third electrode 15.

[0029] Among them, the battery substrate 11 has a front surface M and a back surface S which are oppositely arranged. The first electrode 12 and the second electrode 13 are located on the back surface S of the battery substrate 11. The passivated contact structure 14 is located on the front surface M of the battery substrate 11. The third electrode 15 is located on the side of the passivated contact structure 14 away from the battery substrate 11.

[0030] In the embodiments of the present application, the full-back-contact battery is an Interdigitated Back Contact (IBC) solar cell. IBC is a technology that moves both the positive and negative electrodes of a solar cell to the back of the cell. Correspondingly, the battery substrate 11 can be a silicon substrate, which is used to collect solar energy and convert it into electrons. Further, the silicon substrate can be an n-type or p-type silicon substrate.

[0031] In the embodiments of the present application, the first electrode 12 and the second electrode 13 respectively serve as the positive and negative electrodes of the battery, and are both distributed on the back surface S of the battery substrate 11, which is used to provide an electrical connection port on the back surface S of the battery to be electrically connected to an external circuit and supply power to the external circuit.

[0032] In the embodiments of the present application, the third electrode 15 is used to provide an electrical connection port on the front surface M of the battery. In practical applications, other batteries can be stacked on the front surface M of the battery. The third electrode 15 can be used to be connected in series with other batteries to form a tandem cell. The embodiments of the present application do not impose special restrictions on the implementation form of other batteries. For example, other batteries can be perovskite batteries, and the positive or negative electrode of other batteries is connected in series with the third electrode 15 to form a tandem cell.

[0033] In the embodiments of the present application, a passivated contact structure 14 is provided between the third electrode 15 and the battery substrate 11. The passivated contact structure 14 can provide good surface passivation for the front surface M of the battery substrate 11, effectively reducing surface recombination and metal contact recombination, thereby effectively improving the open-circuit voltage and short-circuit current of the front surface of the battery.

[0034] According to the technical solution of the full-back-contact battery provided by the embodiments of the present application, by disposing the first electrode and the second electrode of the full-back-contact battery on the back surface of the battery substrate, and at the same time disposing a third electrode on the front surface of the battery substrate, the third electrode can provide an electrical connection port on the front surface of the full-back-contact battery, and can be used to form a stacked battery in series with other batteries, which is beneficial to realizing the application of the full-back-contact battery in the preparation of the stacked battery. A passivation contact structure is also disposed on the front surface of the battery substrate, and the passivation contact structure can provide good surface passivation for the front surface of the battery substrate, and can effectively reduce surface recombination and metal contact recombination.

[0035] In some embodiments, as Figure 1 shown, the passivation contact structure 14 includes a tunneling oxide layer 141 and a polysilicon layer 142; the tunneling oxide layer 141 is located on the front surface M of the battery substrate 11 opposite to the back surface S; the polysilicon layer 142 is located on the side of the tunneling oxide layer 141 away from the battery substrate 11; the third electrode 15 is located on the side of the polysilicon layer 142 away from the battery substrate 11. Among them, the ultra-thin tunneling oxide layer 141 can enable majority carriers electrons to tunnel into the polysilicon layer 142, while blocking the recombination of minority carriers holes. Then, the electrons are laterally transported in the polysilicon layer 142 and collected by the metal, thereby greatly reducing the metal contact recombination current, and further effectively improving the open-circuit voltage and short-circuit current of the battery.

[0036] In some embodiments, the polysilicon layer 142 can be a doped polysilicon thin film, and the polysilicon layer 142 can be doped with phosphorus or boron to form a pn junction and be electrically connected to the third electrode 15.

[0037] In some embodiments, the third electrode 15 is a transparent conductive structure, and the transparent conductive structure can be a transparent conductive thin film. Among them, the material of the transparent conductive structure is a transparent conductive material, and the transparent conductive material can include one or more of transparent conductive materials such as indium tin oxide and zinc oxide.

[0038] In some embodiments, the back surface S of the battery substrate 11 includes a P-type region and an N-type region for forming a pn junction. The first electrode 12 is correspondingly located in the P-type region, and the first electrode 12 is a positive electrode. As Figure 1 shown, an emitter 16 is further disposed between the first electrode 12 and the back surface S of the battery substrate 11. The first electrode 12 is connected to the emitter 16, and the emitter 16 can form a pn junction with the battery substrate 11 in the P-type region, effectively shunting carriers.

[0039] In some embodiments, the second electrode 13 is correspondingly located in the N-type region, and the second electrode 13 is a negative electrode. As Figure 1As shown, a back surface field structure 17 is further provided between the second electrode 13 and the back surface S of the battery substrate 11. The second electrode 13 is connected to the back surface field structure 17. The back surface field structure 17 can passivate the N-type region of the back surface S of the battery substrate 11, form a high-low junction with the battery substrate 11 in the N-type region, and enhance the carrier separation ability.

[0040] In some embodiments, the thickness range of the tunneling oxide layer 141 can be set to 1 nanometer to 2 nanometers.

[0041] In some embodiments, the thickness range of the polysilicon layer 142 can be set to 1 nanometer to 1000 nanometers.

[0042] In some embodiments, the thickness range of the third electrode 15 can be set to 1 nanometer to 1000 nanometers.

[0043] In some embodiments, an isolation band is further provided between the emitter 16 and the back surface field structure 17, and the isolation band is used to isolate the emitter 16 and the back surface field structure 17.

[0044] In some embodiments, as Figure 1 shown, a passivation film 18 is provided on the side surface of the emitter 16 and the back surface field structure 17 facing away from the battery substrate 11, and the passivation film 18 can play a role in passivation and antireflection.

[0045] Figure 2 FIG. is a schematic flow chart of a method for manufacturing a full back-junction battery provided by an embodiment of the present application. An embodiment of the present application also provides a method for manufacturing a full back-junction battery. Referring to Figure 2 the following, the method for manufacturing the full back-junction battery includes:

[0046] Step S21: Provide a battery substrate, which has a front surface and a back surface opposite to the front surface.

[0047] Among them, the battery substrate can adopt an N-type or P-type silicon substrate.

[0048] In some embodiments, the front surface of the battery substrate is textured, and the obtained morphology includes a positive pyramid, an inverted pyramid or other light-trapping geometric patterns.

[0049] In some embodiments, a pn junction is formed by making a P-type region and an N-type region on the back surface of the battery substrate.

[0050] Step S22: Form a passivation contact structure on the front surface of the battery substrate.

[0051] Among them, the passivated contact structure includes a tunneling oxide layer and a polysilicon layer; a passivated contact structure is formed on the front surface of the cell substrate, including: forming a tunneling oxide layer on the front surface of the cell substrate; forming a polysilicon layer on the side of the tunneling oxide layer away from the cell substrate, and a third electrode is formed on the side of the polysilicon layer away from the cell substrate.

[0052] In some embodiments, a thermal oxidation method can be used to form the tunneling oxide layer, and a doped polysilicon thin film is deposited on the side of the tunneling oxide layer away from the cell substrate to form the polysilicon layer.

[0053] Step S23: Form a third electrode on the side of the passivated contact structure away from the cell substrate.

[0054] Deposit a transparent conductive thin film on the side of the passivated contact structure away from the cell substrate to form the third electrode.

[0055] Step S24: Form a first electrode and a second electrode on the back surface of the cell substrate.

[0056] Print metal electrode grid lines on the P-type region and the N-type region on the back surface of the cell substrate to form the first electrode and the second electrode.

[0057] In some embodiments, before forming the first electrode and the second electrode on the back surface of the cell substrate, the preparation method further includes: forming an emitter and a back surface field structure on the back surface of the cell substrate; forming a passivation film on the surface of the emitter and the back surface field structure away from the cell substrate; performing a patterning process on the passivation film to form a first via corresponding to the emitter and a second via corresponding to the back surface field structure. Among them, the first via exposes a part of the surface of the corresponding emitter to be in contact and connection with the first electrode formed subsequently, and the second via exposes a part of the surface of the corresponding back surface field structure to be in contact and connection with the second electrode formed subsequently.

[0058] Further, forming the first electrode and the second electrode on the back surface of the cell substrate includes: forming the first electrode in the first via, and the first electrode is connected to the emitter through the first via; forming the second electrode in the second via, and the second electrode is connected to the back surface field structure through the second via.

[0059] In the embodiments of the present application, the preparation method of the full-back junction cell is used to prepare the full-back junction cell of the above embodiments. For related descriptions, reference can be made to the related descriptions of the full-back junction cell in the above embodiments, which will not be elaborated here.

[0060] It is understandable that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present application, and the above specific embodiments do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A full-back contact battery, characterized in that, Comprising: A battery substrate; A first electrode and a second electrode, located on the back surface of the battery substrate. The back surface of the battery substrate includes a P-type region and an N-type region. The first electrode is correspondingly located in the P-type region, and the first electrode is the positive electrode. An emitter is further provided between the first electrode and the back surface of the battery substrate, and the emitter is used to form a PN junction with the battery substrate in the P-type region. The second electrode is correspondingly located in the N-type region, and the second electrode is the negative electrode. A back surface field structure is further provided between the second electrode and the back surface of the battery substrate, and the back surface field structure is used to form a high-low junction with the battery substrate in the N-type region. An isolation strip is further provided between the emitter and the back surface field structure, and the isolation strip is used to isolate the emitter and the back surface field structure.

2. The all-back contact battery according to claim 1, wherein, The all-back-junction battery includes a passivation contact structure and a third electrode. The passivation contact structure is located on the front surface of the battery substrate opposite to the back surface. The third electrode is located on the side of the passivation contact structure away from the battery substrate.

3. The all-back contact battery according to claim 2, wherein, The passivation contact structure includes a tunneling oxide layer and a polysilicon layer; The tunneling oxide layer is located on the front surface of the battery substrate opposite to the back surface; The polysilicon layer is located on the side of the tunneling oxide layer away from the battery substrate; The third electrode is located on the side of the polysilicon layer away from the battery substrate.

4. The all-back-contact battery according to claim 3, wherein The polysilicon layer is doped with phosphorus or boron.

5. The all-back contact battery according to any one of claims 2-4, characterized in that The third electrode is a transparent conductive structure.

6. The all-back contact battery according to claim 5, wherein, The material of the transparent conductive structure includes one or more of indium tin oxide and zinc oxide.

7. The all-back-contact battery according to claim 3 or 4, characterized in that, The thickness range of the tunneling oxide layer is from 1 nanometer to 2 nanometers.

8. The all-back contact battery according to claim 3 or 4, characterized in that, The thickness range of the polysilicon layer is from 1 nanometer to 1000 nanometers.

9. The all-back-contact battery according to any one of claims 2-4, characterized in that, The thickness range of the third electrode is from 1 nanometer to 1000 nanometers.

10. The all-back-contact battery according to any one of claims 2-4, characterized in that, The all-back-junction battery includes a passivation film, and the passivation film is located on the side of the emitter and the back surface field structure away from the battery substrate.

11. The all-back-junction battery according to claim 10, wherein, A first via hole and a second via hole are provided on the passivation film. The first via hole exposes part of the emitter, and the second via hole exposes part of the back surface field structure. The first electrode contacts the emitter through the first via hole, and the second electrode contacts the back surface field structure through the second via hole.

12. A stacked battery, characterized in that, Comprising: A battery to be connected and the all-back-junction battery according to any one of claims 1-11 above. The all-back-junction battery includes a third electrode, and the third electrode is located on one side of the front surface of the battery substrate of the all-back-junction battery; The battery to be connected is located on the side of the third electrode away from the battery substrate, and the battery to be connected and the third electrode are connected in series.

13. A method for preparing a full-back contact battery, characterized in that, Comprising: Providing a battery substrate, the battery substrate having a front surface and a back surface opposite to the front surface; Forming an emitter and a back surface field structure on the back surface of the battery substrate; A first electrode and a second electrode are formed on the back side of the battery substrate, the back side of the battery substrate includes a P-type region and an N-type region, the first electrode is correspondingly located in the P-type region, the first electrode is a positive electrode, the first electrode is formed on the side of the emitter away from the battery substrate, and the emitter is used to form a PN junction with the battery substrate in the P-type region; the second electrode is correspondingly located in the N-type region, the second electrode is a negative electrode, the second electrode is formed on the side of the back surface field structure away from the battery substrate, and the back surface field structure is used to form a high-low junction with the battery substrate in the N-type region; an isolation belt is also formed between the emitter and the back surface field structure, and the isolation belt is used to isolate the emitter from the back surface field structure.

14. The preparation method according to claim 13, characterized in that, The preparation method comprises: forming a passivation contact structure on the front side of the battery substrate; A third electrode is formed on the side of the passivation contact structure facing away from the battery base body.

15. The preparation method according to claim 14, characterized in that, The passivation contact structure comprises a tunneling oxide layer and a polysilicon layer; the passivation contact structure is formed on the front side of the battery substrate, comprising: forming a tunneling oxide layer on the front side of the battery substrate; A polysilicon layer is formed on a side of the tunnel oxide layer away from the battery substrate, and the third electrode is formed on a side of the polysilicon layer away from the battery substrate.

16. The preparation method according to claim 15, characterized in that, Before forming the first electrode and the second electrode on the back side of the battery substrate, the preparation method further comprises: Forming a passivation film on the surface of the emitter and the back surface field structure facing away from the battery substrate; Performing a patterning process on the passivation film to form a first via hole corresponding to the emitter and a second via hole corresponding to the back surface field structure; A first electrode and a second electrode are formed on the back side of the battery substrate, comprising: forming the first electrode in the first via hole, wherein the first electrode is connected to the emitter through the first via hole; The second electrode is formed in the second via hole, and the second electrode is connected to the back surface field structure through the second via hole.

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