Back contact battery and production process thereof

Abstract

The invention discloses a back contact battery and a production process thereof, and the back contact battery comprises a substrate layer which is provided with a light receiving surface and a backlight surface; a front passivation layer; the heterojunction composite layer comprises an electron current-carrying assembly and a hole current-carrying assembly which are deposited and formed on a backlight surface, and the back conductive layer and the heterojunction composite layer are enclosed to form an isolation through groove; and an electrode assembly including a first electrode and a second electrode. According to the back contact cell and the production process thereof, the electron current-carrying assembly and the hole current-carrying assembly which are deposited and formed on the backlight surface are combined to form the heterojunction composite layer, and the isolation through groove is formed in the back surface of the substrate layer in a laser grooving manner, so that the process steps are simplified, and the problem of complex and tedious process is solved; and the types of equipment required in the production process are reduced, the production efficiency and the yield are greatly improved, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and in particular to a back contact cell and a production process thereof. Background Art

[0002] Solar cell technology is the most widely used clean energy technology, among which crystalline silicon solar cells occupy about 90% of the global market share. In recent years, high-efficiency crystalline silicon solar cells are mainly heterojunction cells and back contact cells. Back contact combined with heterojunction cells can obtain heterojunction back contact cells, also known as HBC cells. This type of cell has the advantages of both back contact cells and heterojunction cells. Since there is no grid line blocking the front of the cell, the shading loss on the front is greatly reduced, and the short-circuit current is increased. On the other hand, the high-quality passivation of the c-Si surface by hydrogenated amorphous silicon reduces the interface recombination, thereby bringing high open circuit voltage.

[0003] In the existing technology, although HBC cells can improve the photoelectric conversion efficiency by at least 0.5% compared with HJT cells, there are still many technical problems that restrict the large-scale production of HBC technology, mainly manifested in: First, in the production process of HBC cells, fragmentation and rework are often prone to occur, and the yield of the cells is low, making it difficult to increase the yield of large-scale HBC battery mass production to more than 90%, resulting in high production costs; second, in the production process of HBC cells, a variety of different types of instruments and devices are required, which not only increases the cost of the entire production chain, but also has a complex process, is time-consuming, and is difficult to produce quickly, reducing production efficiency. In addition, the photoelectric conversion efficiency of existing HBC cells is limited, and there is still room for further improvement.

[0004] Therefore, it is necessary to improve the back contact battery and its production process in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects existing in the prior art and to provide a back-contact cell and its production process which can improve the yield to be suitable for large-scale batch production, reduce the types of devices required in the production chain, reduce the process steps to reduce costs and improve production efficiency and further improve photovoltaic power generation efficiency.

[0006] In order to solve the above technical problems, the present invention provides a back contact battery, comprising: A substrate layer, wherein the substrate layer has a light-receiving surface and a light-receiving surface distributed along a thickness direction of the substrate layer; A front passivation layer, the front passivation layer is stacked and connected with the light receiving surface; A photoelectric conversion conductive composite layer, the photoelectric conversion conductive composite layer comprising a back conductive layer and a heterojunction composite layer connected in layers, the heterojunction composite layer being connected to the backlight surface, the heterojunction composite layer comprising electron current-carrying components and hole current-carrying components that are distributed at intervals and connected in sequence, the electron current-carrying components and the hole current-carrying components being formed on the backlight surface by deposition, the back conductive layer and the heterojunction composite layer enclosing isolation through grooves, the number of the isolation through grooves being equal to and corresponding to the number of the electron current-carrying components; The electrode assembly comprises a first electrode and a second electrode which are spaced apart from each other, wherein the first electrode is connected to the electron current-carrying assembly through the back conductive layer, and the second electrode is connected to the hole current-carrying assembly through the back conductive layer.

[0007] Preferably, in order to collect electrons (negative charge carriers), the electron current-carrying component includes a first back passivation layer, an n-type semiconductor layer, and a second back passivation layer which are sequentially stacked and connected, and the hole current-carrying component includes a third back passivation layer and a p-type semiconductor layer which are sequentially stacked and connected, and the first back passivation layer and the third back passivation layer are both connected to the backlight surface.

[0008] Preferably, in order to facilitate the formation of spaced electron current-carrying components, the spaced electron current-carrying components are formed by a composite electron current-carrying film formed by a first back passivation film, an n-type semiconductor film and a second back passivation film stacked in sequence on the backlight surface, which is formed by preliminary laser grooving. Adjacent electron current-carrying components and the backlight surface are enclosed to form a first deposition groove. The inner wall of the first deposition groove is combined with a side of the electron current-carrying component facing away from the backlight surface to form a first deposition surface. The hole current-carrying component is formed on the first deposition surface.

[0009] Preferably, in order to collect holes (positive charge carriers), the hole current carrier component includes a third back passivation layer and a p-type semiconductor layer stacked on the third back passivation layer and facing away from the backlight surface.

[0010] Preferably, in order to facilitate the formation of spaced hole current carrier components, the spaced hole current carrier components are formed by a hole current carrier composite film composed of a third back side passivation film and a p-type semiconductor film which are sequentially stacked and connected on the backlight surface, and are formed by mid-stage laser grooving and late-stage laser grooving.

[0011] Preferably, in order to facilitate the formation of a back conductive layer, after the mid-stage laser grooving, the third back passivation film, the p-type semiconductor film and the electron current-carrying component are combined to form a second deposition groove, and the inner wall of the second deposition groove and the side of the p-type semiconductor film facing away from the backlight surface are combined to form a second deposition surface, and the back conductive layer is formed by the back conductive film stacked on the second deposition surface through the late laser grooving, and the late laser grooving acts on the back conductive film and the hole current-carrying component in sequence.

[0012] Preferably, in order to avoid short circuit, the back conductive layer and the heterojunction composite layer also enclose to form insulating grooves, the number of the insulating grooves is equal to and corresponds one to one with the electron current carrying components, and the insulating grooves and the isolation grooves cooperate with each other to separate the electron current carrying components and the hole current carrying components.

[0013] In order to solve the above technical problems, the present invention also provides a production process of a back contact battery, comprising the following steps: S100, cleaning and texturing: cleaning and texturing the n-type crystalline silicon to form a substrate layer, wherein the two sides of the substrate layer are respectively a light-receiving side and a backlight side; S200, depositing a passivation conductive composite layer and a photoelectric conversion conductive composite layer: depositing a front passivation layer and a photoelectric conversion conductive composite layer on the light-receiving surface and the backlight surface of the substrate layer obtained in S100, respectively, the photoelectric conversion conductive composite layer comprising a heterojunction composite layer and a back conductive layer deposited in sequence and connected in a stacked manner, the heterojunction composite layer being formed by a combination of electron current-carrying components and hole current-carrying components deposited in sequence and spaced apart on the backlight surface of the substrate layer obtained in S100; S300, late laser grooving: using a laser to irradiate the back conductive layer with a laser, so that under the laser irradiation, the side of each electron current-carrying component facing away from the substrate layer is exposed and an isolation groove is formed, wherein the isolation groove is formed by enclosing the back conductive layer and the heterojunction composite layer, and the isolation groove corresponds to the electron current-carrying component one by one; S400, preparing an electrode assembly; printing a metal grid line on the back conductive layer to form a first electrode connected to the electron current carrying assembly through the back conductive layer and a second electrode connected to the hole current carrying assembly through the back conductive layer.

[0014] Preferably, in order to facilitate the rapid deposition of electron current-carrying components and hole current-carrying components distributed at intervals on the backlight surface, step S200 includes the following steps: S210, depositing a first back passivation film, an n-type semiconductor film, and a second back passivation film in sequence on the backlight surface of the substrate layer obtained in S100, so that the first back passivation film, the n-type semiconductor film, and the second back passivation film are stacked and connected to form an electron current carrying composite film; S220, early laser grooving: using a laser to irradiate the electron current carrying composite film with laser, the backlight surface is partially exposed under the laser irradiation and a first deposition groove is formed, the first deposition groove is formed by the backlight surface and the electron current carrying composite film, so that the electron current carrying composite film is divided into at least two electron current carrying components distributed at intervals, and the inner wall of the first deposition groove and the side of each electron current carrying component 4 facing away from the substrate layer are combined to form a first deposition surface; S230, sequentially depositing a third back passivation film and a p-type semiconductor film on the first deposition surface obtained in S220, so that the third back passivation film and the p-type semiconductor film are sequentially stacked and connected to form a hole current carrying composite film; S240, mid-term laser grooving: using a laser to irradiate the hole current carrier composite film with a laser, the irradiation position is directly opposite to the electron current carrier component 4, under the laser irradiation, the side of the electron current carrier component 4 facing away from the substrate layer is partially exposed and forms a second deposition groove, the second deposition groove is formed by enclosing the third back passivation film, the p-type semiconductor film and the second back passivation film, so that the hole current carrier composite film is divided into at least two hole current carrier components distributed at intervals, the inner wall of the second deposition groove and the side of each hole current carrier component facing away from the substrate layer are combined to form a second deposition surface for depositing a back conductive layer; S250, depositing a front passivation layer on the light-receiving surface of the substrate layer obtained in S100; S260 , depositing a back conductive layer on the second deposition surface obtained in S240 .

[0015] Preferably, in order to avoid short circuit, step S310, final laser grooving, is further included between step S300 and step S400, or after step S300: a laser is used to irradiate the back conductive layer with a laser, and under the laser irradiation, a side of each electron current-carrying component facing away from the substrate layer is exposed and an insulating groove is formed, the insulating groove is formed by enclosing the back conductive layer and the heterojunction composite layer, and the insulating groove corresponds to the electron current-carrying component one by one, and the insulating groove and the isolation groove cooperate with each other to separate the electron current-carrying component and the hole current-carrying component.

[0016] In summary, compared with the prior art, the back contact battery and its production process of the present invention form a heterojunction composite layer by combining electron current carrying components and hole current carrying components deposited on the backlight surface, and form isolation grooves on the back of the substrate layer by laser grooving, which is conducive to simplifying the process steps, solving the problem of complex and cumbersome processes, reducing the types of equipment required in the production process, greatly improving production efficiency and yield rate and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1is a schematic structural diagram of a back contact battery substrate layer of the present invention; Figure 2 is Figure 1 A schematic structural diagram of a first back side passivation film deposited on the back side of a substrate layer; Figure 3 is Figure 2 A schematic diagram of the structure of depositing an n-type semiconductor film on the first back side passivation film; Figure 4 is Figure 3 A schematic diagram of the structure of depositing a second back passivation film on an n-type semiconductor film; Figure 5 is Figure 4 Schematic diagram of the structure of laser grooving on the electron current-carrying composite film; Figure 6 is Figure 5 A schematic diagram of a structure in which a third back passivation film is deposited on a first deposition surface; Figure 7 is Figure 6 A schematic diagram of a structure in which a p-type semiconductor film is deposited on a third back passivation film; Figure 8 is Figure 7 Schematic diagram of the structure of laser grooving on the hole-carrying composite film; Fig. 9 is Figure 7 A schematic diagram of the structure of depositing a front passivation layer on the light-receiving surface of a substrate layer; Fig.10 is Fig. 9 A schematic diagram of the structure of a front passivation layer and a conductive film deposited on a second deposition surface; Fig.11 is Fig.10 Schematic diagram of the structure of laser grooving on the back conductive film; Fig.12 is Fig.11 A schematic diagram of the structure of preparing an electrode assembly on a back conductive film; Fig.13 is Fig.12 Schematic diagram of the structure of laser grooving on the back conductive film; Fig.14 is a flow chart of a first embodiment of a process for producing a back contact battery substrate layer of the present invention; Fig.15 It is a flow chart of depositing a front passivation layer and a photoelectric conversion conductive composite layer in the first embodiment of the back contact battery substrate layer production process of the present invention; Fig.16 is a flow chart of a second embodiment of a process for producing a back contact battery substrate layer of the present invention; Fig.17 It is a structural schematic diagram of a prior art HJT battery; Fig.18 It is a schematic diagram of the structure of a prior art TOPCon battery; Fig.19 is a table of relevant performance data of a back-contact battery based on the production process of the second embodiment; Fig. 20 It is a table of relevant performance data of HJT batteries in the prior art; Fig.21 It is a table of relevant performance data of the prior art TOPCon battery; In the figure: 1, substrate layer; 11, light-receiving surface; 12, backlight surface; 2, second deposition channel; 3, front passivation layer; 4, electron current-carrying component; 40, electron current-carrying composite film; 41, first back passivation layer; 410, first back passivation film; 42, n-type semiconductor layer; 420, n-type semiconductor film; 43, second back passivation layer; 430, second back passivation film; 5, hole current-carrying component; 50, hole current-carrying composite film; 51, third back passivation layer; 510, third back passivation film; 52, p-type semiconductor layer; 520, p-type Semiconductor film; 6. back conductive layer; 60. back conductive film; 7. electrode assembly; 71. first electrode; 72. second electrode; 8. isolation groove; 9. first deposition groove; 10. insulation groove; A1. first comparison substrate layer; A2. first comparison front hydrogenated intrinsic amorphous silicon layer; A3. first comparison hydrogenated microcrystalline silicon n-type doped layer; A4. first comparison conductive layer; A5. first comparison reverse hydrogenated intrinsic amorphous silicon layer; A6. first comparison hydrogenated microcrystalline silicon p-type doped layer; A7. first comparison reverse conductive layer; A8. first comparison silver electrode; B1. second comparison substrate layer; B2. second comparison p+ diffusion layer; B3. second comparison front passivation layer; B4. second comparison front anti-reflection layer; B5. second comparison reverse passivation layer; B6. second comparison n-type polysilicon thin film layer; B7. second comparison reverse anti-reflection layer; B8. second comparison silver electrode. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0019] First embodiment

[0020] like Fig.12 As shown, the back contact battery of the first embodiment of the present invention comprises: A substrate layer 1, wherein the substrate layer 1 has a light receiving surface 11 and a backlight surface 12 distributed along the thickness direction thereof; A front passivation layer 3, the front passivation layer 3 is stacked and connected with the light receiving surface 11; A photoelectric conversion conductive composite layer, the photoelectric conversion conductive composite layer includes a back conductive layer 6 and a heterojunction composite layer connected in layers, the heterojunction composite layer is connected to the backlight surface 12, the heterojunction composite layer includes electron current-carrying components 4 and hole current-carrying components 5 that are distributed at intervals and connected in sequence, the electron current-carrying components 4 and the hole current-carrying components 5 are both formed on the backlight surface 12 by deposition, the back conductive layer 6 and the heterojunction composite layer are enclosed to form isolation through grooves 8, and the number of isolation through grooves 8 is equal to that of the electron current-carrying components 4 and corresponds one to one; The electrode assembly 7 includes a first electrode 71 and a second electrode 72 that are spaced apart from each other. The first electrode 71 is connected to the electron current-carrying assembly 4 through the back conductive layer 6 , and the second electrode 72 is connected to the hole current-carrying assembly 5 through the back conductive layer 6 .

[0021] Compared with the mask method in the prior art, in this embodiment, the electron current-carrying component 4 and the hole current-carrying component 5 constituting the heterojunction composite layer are both deposited on the back of the substrate layer 1. After the heterojunction composite layer is formed, a back conductive layer 6 is deposited on the reverse side, and then the back conductive layer 6 is subjected to a subsequent laser grooving process to form an isolation through groove 8. After ensuring that the electron current-carrying component 4 and the hole current-carrying component 5 are separated, the first electrode 71 and the second electrode 72 are formed by metal grid line printing. That is, the back contact battery in this embodiment only needs to use the device used for deposition and the laser device used for grooving. On the one hand, it reduces the types of equipment required in the production process, which is conducive to reducing the production cost of the battery cell. On the other hand, it is conducive to simplifying the production process, thereby improving production efficiency. In addition, it avoids problems and phenomena such as fragmentation and rework caused by the cumbersome production process, thereby helping to improve the yield rate and is suitable for large-scale batch production.

[0022] Specifically, the substrate layer 1 in this embodiment is mainly an n-type single crystal silicon substrate, that is, nc-Si, which uses phosphorus doped silicon as the base material, provides basic semiconductor properties, and is the basis of photoelectric conversion. The entire material presents n-type conductivity, and its primary function is to absorb sunlight. After sunlight irradiates the silicon wafer, the photon energy is absorbed by silicon atoms, causing the electrons in the silicon to transition from the valence band to the conduction band, forming photogenerated carriers (electron-hole pairs). The photogenerated carriers are separated under the action of the internal electric field of the battery, and the electrons are collected by the n-type semiconductor layer 42, and the holes are collected by the p-type semiconductor layer 52, and current is formed through the external circuit, thereby realizing photoelectric conversion. In addition, the substrate layer 1 also plays a role in structural support, protecting the sensitive structure inside the battery and reducing the interference from the external environment, such as humidity, temperature and mechanical stress.

[0023] The two sides of the substrate layer 1 are the light-receiving surface 11 and the backlight surface 12. When in use, the light-receiving surface 11 faces upward to receive sunlight from above, while the backlight surface 12 faces downward to receive sunlight reflected from the ground or other installation facilities, thereby increasing the amount of sunlight received by the back battery and improving the photoelectric conversion efficiency.

[0024] In order to increase the amount of light absorbed by the substrate layer 1 and reduce the light reflectivity, thereby improving the photoelectric conversion efficiency and increasing the power generation efficiency of the photovoltaic module, the substrate layer 1 in the present invention has its light-receiving surface 11 and the backlight surface 12 both subjected to surface corrosion through a texturing process to form a densely pyramidal velvet light-trapping structure.

[0025] Specifically, the velvet structure is composed of micron-level protrusions and depressions, forming a velvet-like surface morphology, which can effectively reduce light reflection, thereby increasing light absorption rate; after the substrate layer 1 is corroded, many densely distributed square pyramid structures, that is, pyramid structures, will be formed on the surface of the silicon wafer, which form the velvet morphology. The pyramid structure can effectively absorb and scatter sunlight, change the propagation path of light on the surface of the solar cell, thereby reducing the light reflectivity on both sides of the substrate layer, so that more light can be absorbed by the solar cell and then converted into electrical energy. That is, through the velvet structure, the incident light is reflected and refracted multiple times on the surface, changing the direction of light in the silicon wafer, extending the optical path, and generating a light trapping effect, thereby improving the photoelectric conversion efficiency.

[0026] A front passivation layer 3 is stacked and connected on the light-receiving surface 11 . The front passivation layer 3 is SiNx and is formed by deposition, so as to be stacked and connected to the light-receiving surface 11 .

[0027] Specifically, SiNx as the front passivation layer 3 is usually called silicon nitride film, which is an important functional layer, and its main functions are as follows: 1. Anti-reflection effect: SiNx film can effectively reduce the reflection of light and improve the solar cell's ability to absorb sunlight. Since the refractive index of SiNx film is higher than that of glass, after forming a layer of medium on the surface of the cell, it can enhance the ability of sunlight to enter the cell, thereby improving the photoelectric conversion efficiency; 2. Protecting the battery: SiNx film has high corrosion resistance and scratch resistance, which can effectively prevent the battery from being affected by external factors, such as erosion and damage by sunlight, rain, dust and chemical pollutants. This protective effect provides a reliable guarantee for the long-term use of the battery and extends the service life of the battery. 3. Chemical passivation: During the preparation process of SiNx film, a large number of fixed positive charges and free hydrogen atoms will be formed in the film, making the surface in an inversion state, thereby reducing the probability of carriers meeting and recombination on the surface, while the free hydrogen atoms can diffuse to the Si-SiNx interface, further reducing the surface recombination rate, thereby improving the open circuit voltage and conversion efficiency of the battery; 4. Enhanced mechanical strength and chemical stability: SiNx film can also improve the mechanical strength and chemical stability of solar cells, helping to ensure that solar cells maintain good performance under different environmental conditions.

[0028] The back conductive layer 6 is made of ITO film. ITO conductive film has excellent conductive properties and can be used as a transparent electrode in a solar cell to effectively transmit current. It can also significantly reduce the internal resistance of the battery and improve the current collection efficiency, thereby improving the photoelectric conversion efficiency of the solar cell. ITO conductive film also has high light transmittance and can allow a large amount of sunlight to penetrate and shine on the substrate layer 1, which helps to fully absorb sunlight and generate more electrical energy.

[0029] The thickness of the ITO conductive film has a complex effect on the performance of solar cells. On the one hand, the greater the thickness, the better the conductivity, which can reduce the series resistance and ohmic loss. On the other hand, the greater the thickness, the lower the corresponding transparency, which in turn increases light reflection and reduces the amount of sunlight absorbed. Therefore, in order to balance reducing power loss and ensuring the amount of sunlight absorbed, in this embodiment, the thickness of the back conductive layer 6 is preferably controlled at 60-100nm.

[0030] Of course, according to the performance of the above-mentioned ITO conductive film and actual production and use requirements, it can also be selected whether to deposit and form an ITO conductive film on the front passivation layer 3 .

[0031] When preparing the electrode assembly 7, first, a transparent conductive metal layer, preferably a pure copper paste layer, is deposited on the entire surface of the back conductive layer 6, and then a conductive medium with higher stability is printed, such as carbon paste, silver-coated copper paste, silver paste, aluminum paste, etc., or a mixed paste formed by a mixture of at least two of the above pastes, and a conductive medium covering the transparent conductive metal layer is formed by the above paste; then a protective medium is covered on the conductive medium, and the protective medium is preferably a photoresist to achieve the effect of protecting the conductive medium; thereafter, single-sided etching is performed in a wet chemical tank, and the conductive medium can be retained at the position where the protective medium is printed.

[0032] A further improvement is that the electron current-carrying component 4 includes a first back passivation layer 41, an n-type semiconductor layer 42 and a second back passivation layer 43 which are sequentially stacked and connected, and the hole current-carrying component 5 includes a third back passivation layer 51 and a p-type semiconductor layer which are sequentially stacked and connected, and the first back passivation layer 41 and the third back passivation layer 51 are both connected to the backlight surface 12; the electron current-carrying components 4 distributed at intervals are formed by an electron current-carrying composite film 40 which is formed by a combination of a first back passivation film 410, an n-type semiconductor film 420 and a second back passivation film 430 which are sequentially stacked and connected on the backlight surface 12, and is formed by laser grooving in the early stage, and adjacent electron current-carrying components 4 and the backlight surface 12 are enclosed to form a first deposition groove 9, and the inner wall of the first deposition groove 9 is combined with a side of the electron current-carrying component 4 which is back to the backlight surface 12 to form a first deposition surface, and the hole current-carrying component 5 is formed on the first deposition surface.

[0033] like Figure 2-Figure 5 As shown, when preparing the electron current-carrying component 4, firstly, a first back passivation film 410 (such as Figure 2 Then, an n-type semiconductor film 420 (as shown) is deposited on the side of the first back passivation film 410 facing away from the substrate layer 1. Figure 3 As shown, after the deposition is completed, a second back passivation film 430 (as shown in FIG. Figure 4 As shown), at this time, the first back passivation layer 41, the n-type semiconductor layer 42 and the second back passivation layer 43 are connected in sequence to form an electron current-carrying composite film 40. After the electron current-carrying composite film 40 is formed, it is pre-laser grooved. The electron current-carrying composite film 40 is irradiated with a laser so that the backlight surface 12 is partially exposed. At the same time, the electron current-carrying composite film 40 is divided into a plurality of electron current-carrying components 4 distributed at intervals under the action of laser grooves. The electron current-carrying component 4 is formed by the first back passivation layer 41, the n-type semiconductor layer 42 and the second back passivation layer 43 being stacked and connected. After the electron current-carrying component 4 is formed, the laser irradiated part is immediately cleaned to remove the debris remaining on the surface of the backlight surface 12 under laser irradiation, to ensure the cleanliness of the surface of the backlight surface 12, to reduce lattice distortion, to reduce the surface recombination rate, to lay a good foundation for subsequent processes, and thus to improve the quality of battery cell products.

[0034] After adopting the above structure, a plurality of electron current-carrying components 4 can be formed on the backlight surface 12 with intervals, and cooperate with a plurality of hole current-carrying components 5 to form a pn structure. Specifically, in the solar cell, the p+ layer (i.e., the p-type semiconductor layer 52) and the n+ layer (i.e., the n-type semiconductor layer 42) are important components of the solar cell structure, and respectively represent different conductive types and doping layers in the solar cell. Among them, the n-type semiconductor layer 42 mainly plays the role of collecting electrons, i.e., negative charge carriers in the solar cell. When sunlight irradiates the surface of the cell, the electrons generated are collected by the n-type semiconductor layer 42 and guided to the external circuit. Correspondingly, the p-type semiconductor layer 52 mainly plays the role of collecting holes, i.e., positive charge carriers in the solar cell. When sunlight irradiates the surface of the solar cell, photons are absorbed and stimulate electron-hole pairs. After these electron-hole pairs are separated by the built-in electric field, the electrons and holes are collected by the n-type semiconductor layer 42 and the p-type semiconductor layer 52 respectively and guided to the external circuit, thereby generating a circuit. Therefore, the n-type semiconductor layer 42 in the electron current-carrying component 4 and the p-type semiconductor layer 52 in the hole current-carrying component 5 cooperate with each other to form a pn core structure of the battery, generate electromotive force and form current under light, and realize photoelectric conversion.

[0035] Specifically, in this embodiment, the first back passivation film 410 and the second back passivation film 430 are both SiOx passivation films, which can significantly improve the performance of the solar cell. The main functions are as follows: 1. Chemical passivation: The SiOx layer can chemically passivate the defects on the surface of the solar cell, reduce the number of surface recombination centers, thereby reducing the surface recombination rate, and help improve the open circuit voltage and fill factor of the solar cell; 2. Tunneling transmission: The SiOx layer is an ultra-thin oxide layer, and its thickness is usually less than 2nm, to allow tunneling transmission of photocarriers. This structure can realize the extraction of current while ensuring effective passivation, thereby improving the efficiency of solar cells; 3. Simplified process: In this embodiment, the first back passivation film 410 and the second back passivation film 430 are both SiOx films grown by diffusion doping process, which are used as the surface passivation layer of the doping layer of the solar cell. No additional process is required to achieve the growth of the surface passivation layer of the doping layer, which helps to simplify the solar cell preparation process and improve production efficiency. 4. Ensure the stability of battery performance: The use of SiOx layer can also improve the stability of solar cell product quality. Since it is completed at the same time as the doping layer during the diffusion process, it can effectively solve the problem of the influence of the external environment on the passivation quality of the doping layer surface.

[0036] A further improvement is that the hole current carrier component 5 includes a third back passivation layer 51 and a p-type semiconductor layer 52 stacked on the third back passivation layer 51 facing away from the backlight surface 12; the spaced hole current carrier component 5 is formed by a hole current carrier composite film 50 formed by a third back passivation film 510 and a p-type semiconductor film 520 stacked in sequence and connected to the backlight surface 12, which is formed by mid-stage laser grooving and late-stage laser grooving in sequence; after the mid-stage laser grooving, the third back passivation film 510, the p-type semiconductor film 520 and the electron current carrier component 4 are enclosed to form a second deposition groove 2, the inner wall of the second deposition groove 2 is combined with a side of the p-type semiconductor film 520 facing away from the backlight surface 12 to form a second deposition surface, and the back conductive layer 6 is formed by a back conductive film 60 stacked on the second deposition surface through late laser grooving, and the late laser grooving acts on the back conductive film 60 and the hole current carrier component 5 in sequence.

[0037] like Figure 6-Figure 8 As shown, when preparing the hole current carrying component 5, a third back passivation film 510 (such as Figure 6 As shown), a p-type semiconductor film 520 is then deposited on the side of the third back passivation film 510 facing away from the substrate layer 1, so that the third back passivation film 510 and the p-type semiconductor film 520 are sequentially stacked and connected to form a hole current composite film 50, and then a laser is used to irradiate the hole current composite film 50 for mid-term laser grooving, so that the second back passivation layer 43 is partially exposed, and the hole current composite film 50 is divided into a plurality of hole current components 5, and the hole current component 5 is formed by stacking and connecting the third back passivation layer 51 and the p-type semiconductor layer 52. The hole current component 5 and the electron current component 4 are combined with each other to form a pn junction of the solar cell.

[0038] To be more specific, in the present embodiment, the third back passivation layer 51 is an a-Si:H passivation layer, i.e., a hydrogenated amorphous silicon passivation layer, which is mainly composed of amorphous silicon (a-Si) and hydrogen (H). Amorphous silicon is a short-range ordered and long-range disordered material, and the addition of hydrogen can improve its electrical properties and reduce the number of dangling bonds. It can usually be formed by chemical vapor deposition (CVD) such as plasma enhanced chemical vapor deposition (PECVD) on the backlight surface 12 of the nc-Si substrate layer 1. By adopting the above method, a high-quality a-Si:H film can be deposited quickly and uniformly at low temperature.

[0039] The main function of the a-Si:H passivation layer is to passivate the surface. Specifically, in the a-Si:H layer, the hydrogen atoms in amorphous silicon can combine with the dangling bonds on the silicon surface, thereby reducing the surface state density and the number of recombination centers, and reducing the surface recombination rate. This passivation effect helps to improve the open circuit voltage and fill factor and other performance parameters of solar cells. In addition, the a-Si:H passivation layer can also enhance the stability of the battery, to a certain extent resist the erosion and damage of the external environment to the inside of the battery, and extend the service life of the battery.

[0040] Therefore, in this embodiment, after the third back passivation layer 51 is made of an a-Si:H layer, it can help improve the photoelectric conversion efficiency of the solar cell, optimize performance parameters and enhance stability.

[0041] It should be noted that after the mid-term laser grooving and the late-stage laser grooving, in order to remove the impurities generated after the grooving and ensure the cleanliness of the surface, which is conducive to subsequent processing, the irradiated area should be cleaned immediately after laser irradiation.

[0042] According to the back contact battery of this embodiment, the present invention also provides a production process of the back contact battery, such as Fig.14 and Fig.15 As shown, the following steps are included: S100, cleaning and texturing: cleaning and texturing the n-type crystalline silicon to form a substrate layer 1, wherein two sides of the substrate layer 1 are a light receiving side 11 and a backlight side 12; S200, depositing a passivation conductive composite layer and a photoelectric conversion conductive composite layer: depositing a front passivation layer 3 and a photoelectric conversion conductive composite layer on the light-receiving surface 11 and the backlight surface 12 of the substrate layer 1 obtained in S100, respectively, wherein the photoelectric conversion conductive composite layer includes a heterojunction composite layer and a back conductive layer 6 deposited in sequence and connected in a stacked manner, and the heterojunction composite layer is formed by a combination of an electron current-carrying component 4 and a hole current-carrying component 5 that are deposited in sequence and spaced apart on the backlight surface 12 of the substrate layer 1 obtained in S100; S300, later laser grooving: using a laser to irradiate the back conductive layer 6, the side of each electron current-carrying component 4 facing away from the substrate layer 1 is exposed under the laser irradiation and an isolation groove 8 is formed, the isolation groove 8 is formed by the back conductive layer 6 and the heterojunction composite layer, and the isolation groove 8 corresponds to the electron current-carrying component 4 one by one; S400, preparing electrode assembly 7; printing metal grid lines on the back conductive layer 6 to form a first electrode 71 connected to the electron current carrying assembly 4 through the back conductive layer 6 and a second electrode 72 connected to the hole current carrying assembly 5 through the back conductive layer 6.

[0043] Wherein, step S200 includes the following steps: S210, sequentially depositing a first back passivation film 410, an n-type semiconductor film 420, and a second back passivation film 430 on the backlight surface 12 of the substrate layer 1 obtained in S100, so that the first back passivation film 410, the n-type semiconductor film 420, and the second back passivation film 430 are stacked and connected to form an electron current carrying composite film 40; S220, early laser grooving: using a laser to irradiate the electron current carrying composite film 40, the backlight surface 12 is partially exposed under the laser irradiation and a first deposition groove 9 is formed, the first deposition groove 9 is formed by the backlight surface 12 and the electron current carrying composite film 40, so that the electron current carrying composite film 40 is divided into at least two electron current carrying components 4 distributed at intervals, and the inner wall of the first deposition groove 9 and the side of each electron current carrying component 4 facing away from the substrate layer 1 are combined to form a first deposition surface; S230, sequentially depositing a third back passivation film 510 and a p-type semiconductor film 520 on the first deposition surface obtained in S220, so that the third back passivation film 510 and the p-type semiconductor film 520 are sequentially stacked and connected to form a hole current carrying composite film 50; S240, mid-term laser grooving: using a laser to irradiate the hole current carrier composite film 50, the irradiation position is directly opposite to the electron current carrier component 4, under the laser irradiation, the side of the electron current carrier component 4 facing away from the substrate layer 1 is partially exposed and forms a second deposition groove 2, the second deposition groove 2 is formed by enclosing the third back passivation film 510, the p-type semiconductor film 520 and the second back passivation film 430, so that the hole current carrier composite film 50 is divided into at least two hole current carrier components 5 distributed at intervals, the inner wall of the second deposition groove 2 and the side of each hole current carrier component 5 facing away from the substrate layer 1 are combined to form a second deposition surface for depositing the back conductive layer 6; S250, depositing a front passivation layer 3 on the light-receiving surface 11 of the substrate layer 1 obtained in S100; S260 , depositing a back conductive layer 6 on the second deposition surface obtained in S240 .

[0044] Compared with the prior art, the production process of the back contact battery corresponding to the present embodiment abandons the traditional mask method. During production, a deposition process is performed on the backlight surface 12 of the substrate layer 1 to sequentially form a first back passivation film 410, an n-type semiconductor film 420, and a second back passivation film 430. A laser is then used to perform preliminary laser grooving. After the deposition process, a third back passivation film 510 and a p-type semiconductor film 520 are sequentially formed. A laser is then used to perform intermediate laser grooving. A front passivation layer 3 is then deposited on the light-receiving surface 11 of the substrate layer 1. A second deposition groove 2 and a back conductive layer 6 are then deposited on both sides of the substrate layer 1. The back conductive layer 6 is post-laser grooved to form an isolation groove 8. The first electrode 71 and the second electrode 72 are then printed.

[0045] In the entire production process, only deposition processing and laser grooving processing are required. Therefore, the types of equipment required for production can be greatly reduced. On the one hand, the production process and production steps are simplified to improve production efficiency. On the other hand, the equipment required in the production process is reduced, thereby reducing costs. In addition, the cumbersome production steps that lead to the easy breakage and damage of the battery cells and rework are avoided, thereby improving the yield rate and being suitable for large-scale batch production. It should be noted that in the deposition production process, both PEVCD and LPVCD can be used for deposition processing to simplify the deposition and molding steps of various films and improve production efficiency.

[0046] It should be noted that in the above production process, the first back passivation film 410, the second back passivation film 430, the third back passivation film 510 and the front passivation layer 3 are respectively SiOx film, SiOx film, a-Si:H (i) film and SiNx film, and are deposited in the above order, and the deposition temperatures are controlled at 750-950°C, 750-950°C, 170-250°C and 400-500°C, respectively. Further preferably, the deposition temperatures of the first back passivation film 410, the second back passivation film 430, the third back passivation film 510 and the front passivation layer 3 are 850°C, 850°C, 210°C and 400-500°C, respectively. 450℃. It should be noted that when the SiNx film is deposited at high temperature, its deposition temperature is controlled at 400-500℃, and when it is deposited at low temperature, its deposition temperature is controlled within 300℃ to ensure the deposition quality. The above design is adopted mainly because the H in a-Si:H(i) is highly sensitive to temperature. Under high temperature conditions, the passivation effect of this layer will be significantly reduced. Therefore, after depositing the a-Si:H(i) layer, it is not appropriate to use related high-temperature processes. Therefore, when the front passivation layer 3 is deposited after the a-Si:H(i) film is formed, the SiNx layer is usually deposited by a low-temperature process, and the deposition temperature of SiNx is controlled below 300℃.

[0047] Second embodiment

[0048] like Fig.13 As shown, the back contact battery of the second embodiment of the present invention is based on the first embodiment, and the difference is that the back conductive layer 6 and the heterojunction composite layer also enclose to form insulating grooves 10, the number of insulating grooves 10 and the electron current carrying components 4 are equal and one-to-one corresponding, and the insulating grooves 10 and the isolation grooves 8 cooperate with each other to separate the electron current carrying components 4 and the hole current carrying components 5.

[0049] Correspondingly, the production process of the back-contact battery corresponding to the present embodiment is based on the production process corresponding to the first embodiment, with the difference that step S310 and step S400 are further included between them, namely, final laser grooving: using a laser to irradiate the back conductive layer 6 with a laser, and under the laser irradiation, the side of each electron current-carrying component 4 facing away from the substrate layer 1 is exposed and an insulating groove 10 is formed, the insulating groove 10 is formed by the back conductive layer 6 and the heterojunction composite layer, and the isolation groove 8 corresponds one-to-one to the electron current-carrying component 4, and the insulating groove 10 and the isolation groove 8 cooperate with each other to separate the electron current-carrying component 4 and the hole current-carrying component 5.

[0050] By providing the isolation groove 8 and the insulating groove 10, the electron current-carrying component 4 and the hole current-carrying component 5 can be separated to avoid the formation of an internal loop between the two due to the existence of the back conductive layer 6. In this way, by separating the electron current-carrying component 4 and the hole current-carrying component 5, the normal operation of the back contact battery is further guaranteed.

[0051] According to the above production process, make a batch of Fig.13 The solar back contact cell shown in the figure was used, and the photoelectric conversion efficiency (Eff, in %), open circuit voltage (Voc, in V), short circuit current (Isc, in A) and fill factor (FF, in %) of the cell were tested. To ensure the test accuracy, thirteen solar cells from the same production batch were selected for relevant performance tests. The thirteen back contact cells were test samples a to test samples m, and the following results were obtained: Fig.19 It should be noted that, in this batch of solar back-contact cells, the thicknesses of the front passivation layer 3, the substrate layer 1, the first back passivation layer 41, the n-type semiconductor layer 42, the second back passivation layer 43, the third back passivation layer 51, the p-type semiconductor layer 52, and the back conductive layer 6 are 70nm, 110um, 2nm, 14nm, 2nm, 15nm, 9nm, and 100nm, respectively.

[0052] In the above production process, first, a first back passivation film 410, an n-type semiconductor film 420, and a second back passivation film 430 are deposited in sequence on the backlight surface 12 of the substrate layer 1, and then after preliminary laser grooving, a third back passivation film 510 and a p-type semiconductor film 520 are deposited in sequence, and then a front passivation layer 3 is deposited on the light-receiving surface 11 of the substrate layer 1.

[0053] In addition, it should be noted that the deposition sequence of the above film layers is not limited to the method of this embodiment. In the actual production process, there are at least two other deposition sequences, as described below: First, a first back passivation film 410, an n-type semiconductor film 420, and a second back passivation film 430 are sequentially deposited on the backlight surface 12 at a deposition temperature of about 850° C. After the deposition is completed, a front passivation layer 3 is deposited on the light-receiving surface 11 at a deposition temperature of more than 450° C., and then the backlight surface 12 of the substrate layer 1 is pre-laser-grooved, and then a third back passivation film 510 and a p-type semiconductor film 520 are sequentially deposited, and the deposition temperature is controlled within 300° C.; Secondly, a front passivation layer 3 is deposited on the light-receiving surface 11 at a deposition temperature of more than 450°C, and then a first back passivation film 410, an n-type semiconductor film 420, and a second back passivation film 430 are sequentially deposited on the backlight surface 12 at a deposition temperature of about 850°C. After the deposition is completed, a preliminary laser grooving process is performed, and then a third back passivation film 510 and a p-type semiconductor film 520 are sequentially deposited, and the deposition temperature is controlled within 300°C.

[0054] In the two deposition sequences supplemented above, since H in a-Si:H(i) is highly sensitive to temperature, the passivation effect of this layer will be significantly reduced under high temperature conditions. Therefore, high-temperature processes can no longer be used when depositing the a-Si:H(i) layer, that is, the third back passivation film 510, and after the deposition of this film layer is completed, and the deposition temperature must be less than 300°C.

[0055] like Fig.17 As shown, it is a schematic structural diagram of an HJT solar cell sheet in the prior art, including a first comparison substrate layer A1, the front side of the first comparison substrate layer A1, i.e., the light-receiving side, is sequentially stacked and connected with a first comparison front hydrogenated intrinsic amorphous silicon layer A2, a first comparison hydrogenated microcrystalline silicon n-type doped layer A3 and a first comparison conductive layer A4, the back side of the first comparison substrate layer A1, i.e., the backlight side, is sequentially stacked and connected with a first comparison reverse hydrogenated intrinsic amorphous silicon layer A5, a first comparison hydrogenated microcrystalline silicon p-type doped layer A6 and a first comparison reverse conductive layer A7, and both the first comparison conductive layer A4 and the first comparison reverse conductive layer A7 are connected with a first comparison silver electrode A8. Specifically, the first comparison substrate layer A1 is a 110um thick n-type single crystal silicon substrate, the first comparison conductive layer A4 and the first comparison reverse conductive layer A7 are both 100nm thick conductive films, the first comparison front hydrogenated intrinsic amorphous silicon layer A2 and the first comparison reverse hydrogenated intrinsic amorphous silicon layer A5 are 8.5nm and 13nm thick respectively, the first comparison hydrogenated microcrystalline silicon n-type doped layer A3 and the first comparison hydrogenated microcrystalline silicon p-type doped layer A6 are 14.5nm and 8.5nm thick respectively.

[0056] Thirteen HJT solar cells of the above structure from the same production batch were selected as comparative samples a to m, and relevant performance tests were carried out in sequence. The results are as follows: Fig. 20 The data content is shown.

[0057] like Fig.18 As shown, it is a schematic diagram of the structure of a TOPCon solar cell sheet in the prior art, including a second contrast substrate layer B1, the front side of the second contrast substrate layer B1, i.e., the light-receiving side, is sequentially stacked and connected with a second contrast p+ diffusion layer B2, a second contrast front passivation layer B3 and a second contrast front anti-reflection layer B4, the back side of the second contrast substrate layer B1, i.e., the backlight side, is sequentially stacked and connected with a second contrast reverse passivation layer B5, a second contrast n-type polysilicon thin film layer B6 and a second contrast reverse anti-reflection layer B7, and the second contrast substrate layer B1 and the second contrast reverse anti-reflection layer B7 are both connected with a second contrast silver electrode B8. Specifically, the second comparison substrate layer B1 is a 110um thick n-type single crystal silicon substrate, the second comparison front anti-reflection layer B4 and the second comparison rear anti-reflection layer B7 are 80nm thick SiNx layers and 85nm thick SiNx layers respectively, the second comparison p+ diffusion layer B2 is 170nm thick, the second comparison front passivation layer B3 is an 8nm thick AlO layer, the second comparison rear passivation layer B5 is a 2nm thick SiOx layer, and the second comparison n-type polycrystalline silicon thin film layer B6 is 90nm thick.

[0058] Thirteen TOPCon solar cells of the above structure from the same production batch were selected as comparative samples n to z, and relevant performance tests were carried out in sequence, and the following results were obtained: Fig.21 The data content is shown.

[0059] Through the analysis and comparison of the above tables, it can be seen that the solar back cell produced by the present embodiment has basically the same open circuit voltage value as the HJT cell and TOPCon cell in the prior art, and the short circuit current and fill factor are improved. The two work together to significantly improve the photoelectric conversion efficiency, thereby effectively improving the photovoltaic power generation efficiency of the solar cell module. Specifically, the average short circuit current of the back contact cell of the present embodiment is 0.2203% higher than that of the HJT cell, and 1.0816% higher than that of the TOPCon cell. The average fill factor of the back contact cell of the present embodiment is 3.2943% higher than that of the HJT cell, and 3.8271% higher than that of the TOPCon cell. The average photoelectric conversion efficiency of the back contact cell of the present embodiment is 3.5146% higher than that of the HJT cell, and 4.3634% higher than that of the TOPCon cell.

[0060] It should be noted that step S310 and the final laser grooving may also be performed after step S400.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A back contact battery, characterized in that: include: A substrate layer (1), the substrate layer (1) having a light-receiving surface (11) and a backlight surface (12) distributed along the thickness direction of the substrate layer (1); A front passivation layer (3), the front passivation layer (3) being stacked and connected to the light receiving surface (11); A photoelectric conversion conductive composite layer, the photoelectric conversion conductive composite layer comprising a back conductive layer (6) and a heterojunction composite layer which are stacked and connected, the heterojunction composite layer being stacked and connected to the backlight surface (12), the heterojunction composite layer comprising electron current-carrying components (4) and hole current-carrying components (5) which are distributed at intervals and connected in sequence, the electron current-carrying components (4) and the hole current-carrying components (5) being formed on the backlight surface (12) by deposition, the back conductive layer (6) and the heterojunction composite layer enclosing isolation grooves (8), the number of the isolation grooves (8) being equal to and corresponding to the number of the electron current-carrying components (4); An electrode assembly (7), the electrode assembly (7) comprising a first electrode (71) and a second electrode (72) which are spaced apart from each other, the first electrode (71) being connected to the electron current-carrying assembly (4) via the back conductive layer (6), and the second electrode (72) being connected to the hole current-carrying assembly (5) via the back conductive layer (6).

2. The back contact cell according to claim 1, characterized in that: The electron current-carrying component (4) comprises a first back passivation layer (41), an n-type semiconductor layer (42) and a second back passivation layer (43) which are sequentially stacked and connected; the hole current-carrying component (5) comprises a third back passivation layer (51) and a p-type semiconductor layer (52) which are sequentially stacked and connected; the first back passivation layer (41) and the third back passivation layer (51) are both connected to a backlight surface (12).

3. The back contact cell according to claim 2, characterized in that: The electron current-carrying components (4) distributed at intervals are formed by an electron current-carrying composite film (40) formed by a first back surface passivation film (410), an n-type semiconductor film (420) and a second back surface passivation film (430) stacked and connected in sequence on the backlight surface (12) through laser grooving in the early stage; adjacent electron current-carrying components (4) and the backlight surface (12) are enclosed to form a first deposition groove (9); the inner wall of the first deposition groove (9) is combined with a surface of the electron current-carrying component (4) facing away from the backlight surface (12) to form a first deposition surface; and the hole current-carrying component (5) is formed on the first deposition surface.

4. The back contact cell according to claim 1, characterized in that: The hole current-carrying component (5) comprises a third back passivation layer (51) and a p-type semiconductor layer (52) stacked on the third back passivation layer (51) and facing away from the backlight surface (12).

5. The back contact cell according to claim 4, characterized in that: The spaced hole current-carrying components (5) are formed by a hole current-carrying composite film (50) formed by a third back surface passivation film (510) and a p-type semiconductor film (520) which are sequentially stacked and connected to the backlight surface (12), and are formed by sequentially undergoing mid-stage laser grooving and post-stage laser grooving.

6. The back contact cell according to claim 5, characterized in that: After the mid-stage laser grooving, the third back passivation film (510), the p-type semiconductor film (520) and the electron current-carrying component (4) are combined to form a second deposition groove (2); the inner wall of the second deposition groove (2) and a surface of the p-type semiconductor film (520) facing away from the backlight surface (12) are combined to form a second deposition surface; the back conductive layer (6) is formed by a back conductive film (60) stacked on the second deposition surface through post-stage laser grooving; the post-stage laser grooving acts on the back conductive film (60) and the hole current-carrying component (5) in sequence.

7. The back contact cell according to any one of claims 1 to 6, characterized in that: The back conductive layer (6) and the heterojunction composite layer further enclose insulating through grooves (10), the insulating through grooves (10) are equal in number to the electron current-carrying components (4) and correspond one to one, and the insulating through grooves (10) and the isolation through grooves (8) cooperate with each other to separate the electron current-carrying components (4) from the hole current-carrying components (5).

8. A production process for a back contact battery, characterized in that: The following steps are involved: S100, cleaning and texturing: cleaning and texturing the n-type crystalline silicon to form a substrate layer (1), wherein two sides of the substrate layer (1) are respectively a light-receiving side (11) and a backlight side (12); S200, depositing a passivation conductive composite layer and a photoelectric conversion conductive composite layer: depositing a front passivation layer (3) and a photoelectric conversion conductive composite layer on the light-receiving surface (11) and the backlight surface (12) of the substrate layer (1) obtained in S100, respectively, wherein the photoelectric conversion conductive composite layer comprises a heterojunction composite layer and a back conductive layer (6) which are sequentially deposited and stacked, and the heterojunction composite layer is formed by a combination of electron current-carrying components (4) and hole current-carrying components (5) which are sequentially deposited and spaced apart on the backlight surface (12) of the substrate layer (1) obtained in S100; S300, later laser grooving; using a laser to irradiate the back conductive layer (6), so that under the laser irradiation, the side of each electron current-carrying component (4) facing away from the substrate layer (1) is exposed and an isolation groove (8) is formed, wherein the isolation groove (8) is formed by enclosing the back conductive layer (6) and the heterojunction composite layer, and the isolation groove (8) corresponds to the electron current-carrying component (4) one by one; S400, preparing an electrode assembly (7); printing a metal grid line on the back conductive layer (6) to form a first electrode (71) connected to the electron current-carrying assembly (4) through the back conductive layer (6) and a second electrode (72) connected to the hole current-carrying assembly (5) through the back conductive layer (6).

9. The production process of a back contact battery according to claim 8, characterized in that: Step S200 includes the following steps: S210, depositing a first back passivation film (410), an n-type semiconductor film (420), and a second back passivation film (430) in sequence on the backlight surface (12) of the substrate layer (1) obtained in S100, so that the first back passivation film (410), the n-type semiconductor film (420), and the second back passivation film (430) are stacked and connected to form an electron current carrying composite film (40); S220, early laser grooving: using a laser to irradiate the electron current carrying composite film (40), the backlight surface (12) is partially exposed under the laser irradiation and a first deposition groove (9) is formed, the first deposition groove (9) is formed by enclosing the backlight surface (12) and the electron current carrying composite film (40), so that the electron current carrying composite film (40) is divided into at least two electron current carrying components (4) distributed at intervals, and the inner wall of the first deposition groove (9) and the side of each electron current carrying component (4) facing away from the substrate layer (1) are combined to form a first deposition surface; S230, sequentially depositing a third back passivation film (510) and a p-type semiconductor film (520) on the first deposition surface obtained in S200, so that the third back passivation film (510) and the p-type semiconductor film (520) are sequentially stacked and connected to form a hole current carrier composite film (50); S240, mid-stage laser grooving: using a laser to irradiate the hole current carrier composite film (50), with the irradiation position facing the electron current carrier component (4), so that under the laser irradiation, a side of the electron current carrier component (4) facing away from the substrate layer (1) is partially exposed and forms a second deposition groove (2), the second deposition groove (2) is formed by enclosing the third back passivation film (510), the p-type semiconductor film (520) and the second back passivation film (430), so that the hole current carrier composite film (50) is divided into at least two hole current carrier components (5) distributed at intervals, and the inner wall of the second deposition groove (2) and a side of each hole current carrier component (5) facing away from the substrate layer (1) are combined to form a second deposition surface for depositing a back conductive layer (6); S250, depositing a front passivation layer (3) on the light-receiving surface (11) of the substrate layer (1) obtained in S100; S260, depositing a back conductive layer (6) on the second deposition surface obtained in S240.

10. The production process of a back contact battery according to claim 8, characterized in that: Between step S300 and step S400, or after step S300, step S310, final laser grooving is also included: using a laser to irradiate the back conductive layer (6), so that under the laser irradiation, the side of each electron current-carrying component (4) facing away from the substrate layer (1) is exposed and an insulating through groove (10) is formed, wherein the insulating through groove (10) is formed by enclosing the back conductive layer (6) and the heterojunction composite layer, and the isolation through groove (8) corresponds to the electron current-carrying component (4) one by one, and the insulating through groove (10) and the isolation through groove (8) cooperate with each other to separate the electron current-carrying component (4) from the hole current-carrying component (5).

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