N-type TOPCon photovoltaic cell and photovoltaic device

Abstract

The utility model provides an N-type TOPCon photovoltaic cell and photovoltaic equipment, and relates to the technical field of TOPCon cells, and the N-type TOPCon photovoltaic cell comprises an N-type substrate which comprises a light-facing surface and a backlight surface; a P-type diffusion layer, a first polycrystalline silicon layer and a first passivation contact layer are sequentially arranged on the light facing surface from inside to outside; a tunnel oxide layer, a second polycrystalline silicon layer and a second passivation contact layer are sequentially arranged on the backlight surface from inside to outside; wherein a conductive oxide layer is arranged on the outer side of the first passivation contact layer, and the conductive oxide layer is of a transparent curved surface structure, so that the technical problem of low light receiving rate of a PN junction on the surface of the cell in the prior art is solved, and the technical effects of improving the light receiving rate of a light-facing surface of the cell and improving the electric energy efficiency are achieved.

Description

Technical Field

[0001] This disclosure relates to the field of photovoltaic equipment technology, and in particular to an N-type TOPCon photovoltaic cell and photovoltaic device. Background Technology

[0002] Photovoltaic cells are devices that convert sunlight into electrical energy. They are the core components of solar power generation systems. Among them, N-type TOPCON cells have become a hot topic in current photovoltaic research due to their high efficiency, low leakage current, high temperature adaptability, long lifespan, and high flexibility.

[0003] TOPCon batteries use silicon or other semiconductor materials as photosensitive materials. When light shines on the battery surface, the selective contact of high-temperature metal current-carrying ions enables the migration of lithium electrons between the positive and negative electrodes to store and release energy. Therefore, the light absorption rate of the TOPCon battery structure determines the overall energy conversion efficiency of the battery.

[0004] Since existing TOPCon batteries rely on direct sunlight to the PN junction on the battery surface, generating an electromotive force on the N-type substrate and P-type diffusion layer through the photovoltaic effect, their light absorption rate can only be determined by the angle of illumination. Therefore, it is impossible to guarantee the overall energy input and subsequent conductivity of the battery. Utility Model Content

[0005] One of the technical problems this disclosure aims to solve is: how to improve the light absorption rate of the PN junction on the battery surface in order to ensure the overall conductivity of the battery.

[0006] To address the aforementioned technical problems, this disclosure provides an N-type TOPCon photovoltaic cell and photovoltaic device, comprising:

[0007] N-type substrate, which includes a light-facing side and a back-light-facing side;

[0008] The light-facing surface is provided with a P-type diffusion layer, a first polysilicon layer and a first passivation contact layer from the inside out; the back-lighting surface is provided with a tunnel oxide layer, a second polysilicon layer and a second passivation contact layer from the inside out; wherein, a conductive oxide layer is provided on the outside of the first passivation contact layer, and the conductive oxide layer has a transparent curved surface structure.

[0009] In some embodiments, the conductive oxide layer is flexible glass.

[0010] In some embodiments, a reflective layer is provided on the outside of the second passivation contact layer to reduce the light transmitted from the backlight surface to the outside.

[0011] In some embodiments, both the first passivation contact layer and the second passivation contact layer comprise at least one of silicon nitride and silicon oxynitride.

[0012] In some embodiments, a silicon carbide layer is provided between the first polysilicon layer and the first passivation contact layer, and between the second polysilicon layer and the second passivation contact layer.

[0013] In some embodiments, the thickness of polycrystalline silicon is between 10 nm and 60 nm, and the thickness of silicon carbide is between 40 nm and 120 nm.

[0014] In some embodiments, a positive metal electrode is further included, which penetrates the conductive oxide layer, the first polysilicon layer and the first passivation contact layer and then contacts the P-type diffusion layer.

[0015] In some embodiments, a negative metal electrode is further included, which penetrates the second passivation contact layer and then contacts the second polysilicon layer.

[0016] In some embodiments, the conductive oxide layer is provided with a connection hole adapted to the positive metal electrode.

[0017] Secondly, this utility model also provides a photovoltaic device, including the N-type TOPCon photovoltaic cell mentioned above.

[0018] Through the above technical solution, the N-type TOPCon photovoltaic cell provided by this utility model, by setting a conductive oxide layer on the outside of the first passivation contact layer, and the conductive oxide layer having a transparent curved structure, that is, using the conductive oxide layer as the front electrode, improves the overall light transmittance of the cell by the transparent setting, and the curved structure increases the area of ​​the conductive oxide layer in contact with external light per unit volume, thereby increasing the amount of light received. At the same time, to ensure the subsequent cell transfer efficiency of TOPCon, a P-type diffusion layer and a first polycrystalline silicon layer are sequentially set from the inside to the outside on the light-facing surface of the N-type substrate. The back surface is provided with a tunnel oxide layer, a second polysilicon layer, and a second passivation contact layer from the inside out. When light shines on the pn junction through the transparent conductive layer, an electromotive force is generated on the N-type substrate and the P-type diffusion layer by the photovoltaic effect. The positive metal electrode and the back metal electrode are connected to the external load, thereby supplying power to the external load. In addition, the first and second polysilicon layers serve as carrier transport layers. By controlling their doping concentration and thickness, the carrier collection efficiency can be improved. The first and second passivation contact layers are used to reduce contact resistance and improve battery performance.

[0019] Secondly, this utility model also provides a photovoltaic device, including the N-type TOPCon photovoltaic cell described above, which can apply the technical effects of the N-type TOPCon photovoltaic cell described above to various fields such as photovoltaic power plants, solar photovoltaic modules, and photovoltaic cells. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the N-type TOPCon photovoltaic cell disclosed in this embodiment;

[0022] Figure 2 This is a schematic diagram of the internal structure of the first polycrystalline silicon layer in the N-type TOPCon photovoltaic cell disclosed in this embodiment.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. N-type substrate; 2. P-type diffusion layer; 3. First polysilicon layer; 4. First passivation contact layer; 5. Tunnel oxide layer; 6. Second polysilicon layer; 7. Second passivation contact layer; 8. Reflection layer; 9. Silicon carbide layer; 10. Positive metal electrode; 11. Negative metal electrode; 12. Conductive oxide layer. Detailed Implementation

[0025] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0026] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0027] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0029] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0030] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0031] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0032] This invention first improves the light transmission inside the battery. One improvement is that a conductive oxide layer with a transparent curved structure is placed on the outside of the first passivation contact layer, which increases the overall light intake and light reception rate of the battery from the light source. Due to its curved design, the conductive oxide layer uses flexible glass, which is different from the film-based carrier in the prior art. The second improvement is that a reflection layer is set on the outside of the second passivation contact layer, which uses silicon nitride or silicon oxynitride inside to reduce the light transmitted from the backlight surface.

[0033] Secondly, this invention makes technical improvements from the perspective of electron transmission. Polycrystalline silicon absorbs long-wavelength light severely and does not generate electrons after absorption, which wastes this part of the light. However, in order to prevent the silver paste on the back from burning through, a certain thickness must be maintained. Polycrystalline silicon carbide has low parasitic absorption, which can reduce the absorption of long-wavelength light on the back of the TOPCon cell without losing passivation, thereby increasing the short-circuit current of the solar cell and thus improving the cell efficiency.

[0034] Finally, this invention defines the connection between the positive and negative metal electrodes and the battery structure, namely, the positive metal electrode is in contact with the P-type diffusion layer, and the negative metal electrode is in contact with the second polycrystalline silicon layer. The P-type diffusion layer and the positive metal electrode are used to receive electrons from the external circuit, and the second polycrystalline silicon layer and the negative metal electrode are used to store and release lithium ions. Energy is stored and released through the migration of lithium ions between the positive and negative electrodes to form an electric current.

[0035] This invention significantly improves the conversion efficiency and stability of N-type TOPCon photovoltaic cells by optimizing the multi-layer structure design of the battery. The preparation method is simple and efficient, suitable for large-scale industrial production, and reduces production costs.

[0036] Example 1

[0037] This embodiment provides an N-type TOPCon photovoltaic cell, including:

[0038] N-type substrate 1, which includes a light-facing surface and a back-light-facing surface;

[0039] The light-facing surface is provided with a P-type diffusion layer 2, a first polycrystalline silicon layer 3 and a first passivation contact layer 4 from the inside out;

[0040] The backlight surface is provided with a tunnel oxide layer 5, a second polysilicon layer 6, and a second passivation contact layer 7, sequentially from the inside out.

[0041] A conductive oxide layer 12 is provided on the outer side of the first passivation contact layer 4, and the conductive oxide layer 12 has a transparent curved surface structure.

[0042] The technical effects of each component are as follows:

[0043] (1) The tunnel oxide layer uses ultra-thin alumina or silicon oxide materials to effectively passivate silicon surface defects and reduce interface recombination losses.

[0044] (2) The first polysilicon layer 3 and the second polysilicon layer 6 serve as carrier transport layers. By precisely controlling their doping concentration and thickness, the carrier collection efficiency is improved.

[0045] (3) The first passivation contact layer 4 and the second passivation contact layer 7 are made of special materials, which have excellent carrier selectivity and conductivity, reduce contact resistance and improve battery performance.

[0046] (4) The conductive oxide layer 12 with a transparent curved surface structure serves as the front electrode, which improves light absorption and light transmittance while ensuring good electrical contact.

[0047] By setting a conductive oxide layer 12 on the outside of the first passivation contact layer 4, and the conductive oxide layer 12 having a transparent curved structure, the conductive oxide layer 12 serves as the front electrode. The transparency improves the overall light transmittance of the battery, and the curved structure increases the area of ​​the conductive oxide layer 12 in contact with external light per unit volume, thereby increasing the amount of light received. Simultaneously, to ensure the subsequent battery transfer efficiency of TOPCon, a P-type diffusion layer 2, a first polycrystalline silicon layer 3, and a first passivation contact layer 4 are sequentially arranged from the inside to the outside on the light-facing side of the N-type substrate 1; the backlight side follows... The battery consists of a tunnel oxide layer 5, a second polycrystalline silicon layer 6, and a second passivation contact layer 7, arranged from the inside out. When light passes through the transparent conductive layer and irradiates the pn junction, an electromotive force is generated on the N-type substrate 1 and the P-type diffusion layer 2 by the photovoltaic effect. The positive metal electrode 10 and the back metal electrode are connected to the external load, thereby supplying power to the external load. In addition, the first and second crystalline silicon layers serve as carrier transport layers, and the carrier collection efficiency can be improved by controlling their doping concentration and thickness. The first passivation contact layer 4 and the second passivation contact layer 7 are used to reduce contact resistance and improve battery performance.

[0048] Furthermore, the conductive oxide layer 12 is flexible glass.

[0049] Flexible glass has extremely high flexibility and wear resistance, which can effectively adapt to the outdoor environment and maintain the curved structure. Multiple parallel strip lenses can be set on the top of the flexible glass so that the conductive oxide layer 12 can have the effect of multiple convex lenses. That is, after refraction by the conductive oxide layer 12, multiple beam bands are formed on the bottom surface of the glass to achieve the effect of focusing light and have high light transmittance.

[0050] It should be noted that the conductive oxide layer 12 can be indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), which can achieve both light transmission and conductivity.

[0051] Furthermore, an anti-transmittance layer 8 is provided on the outside of the second passivation contact layer 7. The anti-transmittance layer 8 is used to reduce the light transmitted from the back surface to the outside.

[0052] Furthermore, both the first passivation contact layer 4 and the second passivation contact layer 7 comprise at least one of silicon nitride and silicon oxynitride.

[0053] The back reflective layer includes at least one of a back silicon nitride layer and a back silicon oxynitride layer, preferably a composite layer of the back silicon nitride layer and the back silicon oxynitride layer. It needs to meet the condition that the refractive index gradually decreases from the inside of the solar cell to the back surface, so as to increase total internal reflection and achieve the reflective effect.

[0054] Furthermore, a silicon carbide layer 9 is provided between the first polysilicon layer 3 and the first passivation contact layer 4, and between the second polysilicon layer and the second passivation contact layer 7.

[0055] Furthermore, the thickness of polycrystalline silicon is between 10nm and 60nm, while the thickness of silicon carbide is between 40nm and 120nm.

[0056] In existing technologies, the tunneling oxide layer and polycrystalline silicon layer together form a passivation contact structure in TOPCON cells. However, the polycrystalline silicon layer suffers from severe absorption of long-wavelength light and does not generate electrons after absorption, thus wasting some of the light. Therefore, theoretically, the thinner the polycrystalline silicon layer, the better. However, current back-side silver pastes have strong burn-through properties, so the polycrystalline silicon layer also needs to have a certain thickness and cannot be too thin.

[0057] Based on this, the technical solution of this embodiment is as follows: by reducing the thickness of the polycrystalline silicon layer (approximately 90nm-120nm) that was originally set separately, and replacing the reduced portion with a silicon carbide layer 9, the polycrystalline silicon carbide has low parasitic absorption, which can reduce the absorption of long-wavelength light on the back of the TOPCon cell without losing passivation. On the one hand, the silicon carbide layer 9 can protect the back of the cell, preventing the metal paste from burning through the back silicon nitride layer and polycrystalline silicon layer during the screen sintering process due to the polycrystalline silicon layer being too thin, causing the metal paste to directly contact the silicon substrate, increasing metal recombination, and thus causing photovoltaic cell efficiency loss. On the other hand, the silicon carbide layer can provide good contact performance for the back of the cell, which is conducive to current transmission and increases the short-circuit current of the solar cell, thereby improving the cell efficiency.

[0058] Practice has shown that the best results and the most material savings are achieved when the thickness of the polycrystalline silicon layer is between 10nm and 60nm, and the thickness of the silicon carbide layer 9 is between 40nm and 120nm, thus reducing costs and increasing efficiency.

[0059] Furthermore, it also includes a positive metal electrode 10, which penetrates the conductive oxide layer 12, the first polycrystalline silicon layer 3 and the first passivation contact layer 4, and then contacts the P-type diffusion layer 2.

[0060] Furthermore, it also includes a negative metal electrode 11, which penetrates the second passivation contact layer 7 and then contacts the second polysilicon layer 6.

[0061] Furthermore, the conductive oxide layer 12 is provided with connection holes adapted to the positive metal electrode 10.

[0062] The conductive oxide layer 12 has multiple through holes that extend to the P-type diffusion layer 2. The through holes are filled with a filling metal electrode that connects to the positive metal electrode 10, so that the positive metal electrode 10 extends to the P-type diffusion layer 2 through the filling metal electrode. When light shines on the pn junction through the transparent conductive layer, an electromotive force is generated on the N-type substrate 1 and the P-type diffusion layer 2 by the photovoltaic effect. The positive metal electrode 10 and the negative metal electrode 11 are connected to the external load, thereby supplying power to the external load.

[0063] It should be noted that, in this process, by setting the conductive oxide layer 12, the light absorption rate of the solar cell can be improved, and its conductivity can also reduce the series resistance, thereby improving the short-circuit current and fill factor of the solar cell of this invention.

[0064] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0065] Example 2

[0066] This embodiment focuses on the processing method of the N-type TOPCon photovoltaic cell in Embodiment 1, in order to further illustrate the technical effects of this utility model.

[0067] S1: Boron doping is performed on the light-facing side of the N-type substrate 1 to obtain the P-type diffusion layer 2.

[0068] Prior to this step, the following also applies:

[0069] Texturing the N-type substrate 1 yields a nanoscale textured surface. Texturized silicon substrates exhibit better light absorption, which is beneficial for improving photoelectric conversion efficiency. However, boron doping at high temperatures also generates numerous BSG (borosilicate glass) byproducts. Therefore, after obtaining the P-type diffusion layer 2, the back side is first acid-washed to remove the BSG byproducts. Then, the back side is further alkaline-washed and polished on a tank mill to form a polished surface. Finally, the front side is BSG-cleaned to obtain an excellent epitaxial layer growth surface, ensuring the quality of subsequent film growth.

[0070] S2: A tunnel oxide layer and a preparatory layer for the second polysilicon layer 6 are sequentially disposed on the back surface of the N-type substrate 1. The preparatory layer for the second polysilicon layer is subjected to heavy phosphorus doping and annealing crystallization to obtain the second polysilicon layer 6.

[0071] S3: Remove the tunnel oxide-free layer and the second polycrystalline silicon layer 6 from the non-metallic area of ​​the backlight to obtain the battery preform.

[0072] It should be noted that the removal method in step 3 can be physical removal or chemical removal, such as laser etching removal or mask removal, and the appropriate method can be selected according to actual needs.

[0073] S4: A first passivation contact layer 4 and a positive metal electrode 10 are sequentially disposed on the light-facing side of the battery preform; a second passivation contact layer 7 and a negative metal electrode 11 are sequentially disposed on the back-facing side.

[0074] The first passivation contact layer 4 and the second passivation contact layer 7 can be aluminum oxide layers. In this case, ALD (atomic layer deposition) can be used to deposit aluminum oxide on both the light-facing and back-facing surfaces of the battery preform.

[0075] S5. A conductive oxide layer 12 and a reverse transparency layer 8 are provided on the surface of the battery preform. The conductive oxide layer 12 can be physically connected. The reverse transparency layer 8 can be deposited by PECVD on the surface of the battery preform where the second passivation contact layer 7 is provided, at least one of a silicon nitride layer and a silicon oxynitride layer, to improve production efficiency.

[0076] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. An N-type TOPCon photovoltaic cell, characterized in that, Comprising: An N-type substrate (1) comprising a light-receiving surface and a back surface; The light-receiving surface is provided with a P-type diffusion layer (2), a first polysilicon layer (3) and a first passivation contact layer (4) from inside to outside in sequence; The back surface is provided with a tunnel oxide layer (5), a second polysilicon layer (6) and a second passivation contact layer (7) from inside to outside in sequence; Wherein, a conductive oxide layer (12) is provided outside the first passivation contact layer (4), and the conductive oxide layer (12) is a transparent curved surface structure.

2. The N-type TOPCon photovoltaic cell according to claim 1, characterized in that, The conductive oxide layer (12) is a flexible glass.

3. The N-type TOPCon photovoltaic cell according to claim 1, characterized in that, A reverse transmission layer (8) is provided outside the second passivation contact layer (7), and the reverse transmission layer (8) is used to reduce the light transmitted from the back surface to the outside.

4. The N-type TOPCon photovoltaic cell according to claim 3, characterized in that, The first passivation contact layer (4) and the second passivation contact layer (7) both comprise at least one of silicon nitride and silicon oxynitride.

5. The N-type TOPCon photovoltaic cell according to claim 1, characterized in that, A silicon carbide layer (9) is provided between the first polysilicon layer (3) and the first passivation contact layer (4), and between the second polysilicon layer (6) and the second passivation contact layer (7).

6. The N-type TOPCon photovoltaic cell according to claim 5, characterized in that The thickness of the first polysilicon layer (3) and the second polysilicon layer (6) is between 10nm-60nm, and the thickness of the silicon carbide layer (9) is between 40nm-120nm.

7. The N-type TOPCon photovoltaic cell according to claim 1, characterized in that, Further comprising a positive metal electrode (10) which penetrates through the conductive oxide layer (12), the first polysilicon layer (3) and the first passivation contact layer (4), and then contacts the P-type diffusion layer (2).

8. The N-type TOPCon photovoltaic cell according to claim 7, characterized in that, Further comprising a negative metal electrode (11) which penetrates through the second passivation contact layer (7) and then contacts the second polysilicon layer (6).

9. The N-type TOPCon photovoltaic cell according to claim 7, characterized in that, The conductive oxide layer (12) is provided with a connecting hole matched with the positive metal electrode (10).

10. A photovoltaic device, characterized by The N-type TOPCon photovoltaic cell of any one of claims 1-9 is also included.

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