HBC solar cell preparation method and HBC solar cell

Abstract

The invention discloses an HBC solar cell and a preparation method thereof. The method comprises the following steps: selecting a silicon substrate with a first surface and a second surface which are opposite to each other; sequentially forming a tunneling oxide layer, a first doped polycrystalline silicon layer and a dielectric layer on the second surface; removing the dielectric layer, the first doped polycrystalline silicon layer and the tunneling oxide layer on the second region; removing the dielectric layer on the first region and the cross region; sequentially forming an intrinsic silicon-containing film and a second type doped silicon-containing film on the second surface, wherein the second type doped silicon-containing film is doped with second type doping atoms; the intrinsic silicon-containing thin film and the second type doped silicon-containing thin film in the first area are processed through laser, so that the intrinsic silicon-containing thin film is converted into a second doped polycrystalline silicon layer, the second type doped silicon-containing thin film is converted into a third doped polycrystalline silicon layer, and the second doped polycrystalline silicon layer and the third doped polycrystalline silicon layer are both doped with first type doping atoms. The preparation method can simplify the preparation process and reduce laser damage.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a method for preparing an HBC solar cell and an HBC solar cell. Background Art

[0002] Heterojunction (HJT) cells are mainly prepared by depositing an intrinsic α-Si:H layer on the front / back surface of an n-type silicon wafer, then preparing a p-type α-Si:H layer and an n-type α-Si:H layer respectively, and then using low-temperature silver paste through screen printing and drying and curing; in actual production, a transparent conductive oxide film (TCO) can also be deposited on the silicon wafer surface before the metallization process. The above heterojunction solar cell is a new type of high-efficiency battery technology, which combines the advantages of single-crystalline silicon solar cells and amorphous silicon solar cells, and has the characteristics of low preparation process temperature, high conversion efficiency, and good high-temperature characteristics. Since the temperature coefficient of the heterojunction solar cell is small and it has double-sided power generation, it has great market potential and has become the focus of research and breakthrough in the industry.

[0003] In recent years, the optoelectronic performance of heterojunction cells has been greatly improved. To further improve the efficiency of traditional heterojunction cells, people have further improved the structure of heterojunction cells, and a back-contact heterojunction solar cell, that is, an HBC cell (Heterojunction Back Contact), has emerged, which can remove the shading of the grid lines on sunlight and increase the absorption efficiency of incident light. At present, the highest efficiency of this full-back heterojunction solar cell has reached 27.1%.

[0004] However, the manufacturing process of HBC solar cells in the prior art is complex, involving multiple laser processes, multiple chemical processes, and multiple thin-film preparations, resulting in a relatively high cost of the cells, which to a certain extent limits the popularization and application of this technology. Among them, laser film opening mainly uses the high energy of the laser to quickly heat the material locally, causing the material to melt and vaporize, and at the same time generating thermal stress. And the laser has a certain penetration, and the laser will inevitably have an adverse impact on other layers, which is difficult to avoid laser damage to HBC solar cells and affects the photoelectric conversion efficiency.

[0005] How to simplify the manufacturing process of HBC solar cells and avoid or reduce laser damage during the manufacturing process of HBC solar cells is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects in the prior art and provide a method for preparing an HBC solar cell and an HBC solar cell.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] On the one hand, the present invention provides a method for preparing an HBC solar cell, which includes the following steps:

[0009] S1. Select a silicon substrate having opposite first and second surfaces, and the second surface includes a first region, a second region, and an intersection region disposed between the first region and the second region;

[0010] S2. Sequentially form a tunneling oxide layer, a first doped polysilicon layer, and a dielectric layer on the second surface, and the first doped polysilicon layer is doped with a first type of doping atom;

[0011] S3. Remove the dielectric layer, the first doped polysilicon layer, and the tunneling oxide layer on the second region;

[0012] S4. Remove the dielectric layer on the first region and the intersection region;

[0013] S5. Sequentially form an intrinsic silicon-containing film and a second type of doped silicon-containing film on the second surface, the second type of doped silicon-containing film is doped with a second type of doping atom, and the conductive performance after doping the second type of doping atom is opposite to that of the first type of doping atom;

[0014] S6. Use laser to process the intrinsic silicon-containing film and the second type of doped silicon-containing film in the first region, so that the intrinsic silicon-containing film is converted into a second doped polysilicon layer, and the second type of doped silicon-containing film is converted into a third doped polysilicon layer. Both the second doped polysilicon layer and the third doped polysilicon layer are doped with the first type of doping atom.

[0015] Preferably, in step S6, the parameters of the laser treatment include: using ultraviolet laser or green light for treatment, and the pulse width of the ultraviolet laser or green light is at least one of picosecond and femtosecond, and the power is 1-100 W.

[0016] Preferably, the doping concentration of the first doped polysilicon layer is not less than the doping concentration of the second doped polysilicon layer, and the doping concentration of the second doped polysilicon layer is not less than the doping concentration of the third doped polysilicon layer. The doping concentration of the first doped polysilicon layer is not greater than 8×10 20 atoms / cm 3 .

[0017] Preferably, after step S6, the following steps are further included:

[0018] S7. Form a conductive thin film layer on the second surface;

[0019] S8. Remove a part of the conductive thin film layer in the first region, a part of the conductive thin film layer in the second region, and all of the conductive thin film on the intersection region.

[0020] Preferably, after step S8, the following steps are further included:

[0021] S9. Fabricate a first metal electrode and a second metal electrode that are electrically connected to the conductive thin film layer on the first region and the second region respectively;

[0022] Preferably, step S8 includes: printing an etching paste on a partial region of the first region, a partial region of the second region, and the cross region to etch and remove a partial conductive thin film layer of the first region, a partial conductive thin film layer of the second region, and all the conductive thin films on the cross region.

[0023] Preferably, in step S1, the following steps are further included:

[0024] S11. Texturize and / or polish the silicon substrate to form a pyramid structure on the first surface and the second surface;

[0025] Preferably, step S3 includes: removing the dielectric layer on the second region, and polishing and texturizing the exposed surface of the silicon substrate, removing the first doped polysilicon layer and the tunneling oxide layer on the second region, so that the second regions on the first surface and the second surface of the silicon substrate are exposed and a texturized surface structure is formed; or removing the dielectric layer, the first doped polysilicon layer, and the tunneling oxide layer on the second region, and polishing and texturizing the exposed surface of the silicon substrate, so that the second regions on the first surface and the second surface of the silicon substrate are exposed and a texturized surface structure is formed;

[0026] Preferably, in step S3, the dielectric layer on the second region is removed by a laser film opening method;

[0027] Preferably, in step S4, a solvent made of hydrofluoric acid is used to remove the dielectric layer;

[0028] Preferably, step S5 further includes: sequentially forming a passivation layer and an antireflection layer on the first surface;

[0029] Preferably, the dielectric layer is one or more of silicon oxide, silicon nitride, and silicon oxynitride.

[0030] On the other hand, the present invention also provides an HBC solar cell, which includes:

[0031] A silicon substrate having opposite first and second surfaces, the second surface including a first region, a second region, and a cross region disposed between the first region and the second region;

[0032] In the direction away from the silicon substrate, there are successively a tunneling oxide layer disposed in the first region on the second surface, a first doped polysilicon layer uniformly doped with first-type doping atoms, a second doped polysilicon layer, and a third doped polysilicon layer, and the tunneling oxide layer and the first doped polysilicon layer extend to the crossover region;

[0033] An intrinsic silicon-containing film disposed in the second region on the second surface and a second-type doped silicon-containing film doped with second-type doping atoms in the direction away from the silicon substrate, and the intrinsic silicon-containing film and the second-type doped silicon-containing film extend to the side of the first doped polysilicon layer facing away from the silicon substrate in the crossover region, and the first-type doping atoms and the second-type doping atoms have opposite conduction types.

[0034] Preferably, it further includes: a conductive thin film layer disposed on the side surface of the third doped polysilicon layer facing away from the silicon substrate and on the side surface of the second-type doped silicon-containing film facing away from the silicon substrate, and the conductive thin film is disconnected in the crossover region.

[0035] Preferably, the projected area of the conductive thin film layer on the first region on the silicon substrate is smaller than the projected area of the second doped polysilicon layer or the third doped polysilicon layer on the silicon substrate;

[0036] And / or, the projected area of the conductive thin film layer on the second region on the silicon substrate is smaller than the projected area of the intrinsic silicon-containing film or the second-type doped silicon-containing film on the second region on the silicon substrate.

[0037] Preferably, the doping concentration of the first doped polysilicon layer is not less than the doping concentration of the second doped polysilicon layer, and the doping concentration of the second doped polysilicon layer is not less than the doping concentration of the third doped polysilicon layer.

[0038] Preferably, it further includes:

[0039] A first metal electrode disposed on the side surface of the conductive thin film layer in the first region facing away from the silicon substrate;

[0040] A second metal electrode disposed on the side surface of the conductive thin film layer in the second region facing away from the silicon substrate.

[0041] Preferably, the conduction type of the silicon substrate is one of n-type or p-type;

[0042] And / or, the tunneling oxide layer is silicon oxide with a thickness of 0.5 - 3 nm;

[0043] And / or, the thickness of the first doped polysilicon layer is 30 - 300 nm;

[0044] And / or, the intrinsic silicon-containing film is made of at least one of the following materials: microcrystalline silicon, nanocrystalline silicon, amorphous silicon, silicon oxide, silicon carbide; the intrinsic silicon-containing film adopts any of the following forms:

[0045] Single-layer film: A single-layer structure formed of one material, with the same properties throughout the layer;

[0046] Multi-layer film: Composed of multiple layers of different materials, with different properties for each layer;

[0047] Stacked film: Stacked by several materials in a specific order, with cooperation between layers;

[0048] Hybrid film: A single-layer structure formed by mixing several different materials;

[0049] And / or, the second-type doped silicon-containing film uses the following materials: microcrystalline silicon, nanocrystalline silicon, amorphous silicon, silicon oxide, or silicon carbide; the second-type doped silicon-containing film adopts any of the following forms:

[0050] Single-layer film: A single-layer structure formed of one material, with the same properties throughout the layer;

[0051] Multi-layer film: Composed of multiple layers of different materials, with different properties for each layer;

[0052] Stacked film: Stacked by several materials in a specific order, with cooperation between layers;

[0053] Hybrid film: A single-layer structure formed by mixing several different materials;

[0054] And / or, the conductive film layer is a multi-layer or stacked or mixed structure of one or more doped metal oxides, or the conductive film layer is a multi-layer or stacked or mixed structure of one or more doped metal nitrides. The metal oxides include one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium nitride, and the metal nitrides include titanium nitride. The doping elements include one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine;

[0055] And / or, the first metal electrode or the first metal electrode is one or several of a silver electrode, a silver alloy electrode, a copper electrode, a copper alloy electrode, and a multi-layer electrode formed of nickel and / or copper and / or silver to form a stack;

[0056] And / or, a passivation layer and an antireflection layer are sequentially provided on the first surface along the direction away from the silicon substrate. Preferably, the passivation layer is an intrinsic silicon-containing film, or the passivation layer is a combination of an intrinsic silicon-containing film and a doped silicon-containing film, where the thickness of the intrinsic silicon-containing film is 1 to 15 nm, the thickness of the doped silicon-containing film is 1 to 30 nm, or the passivation layer is a doped silicon-containing film. Preferably, the antireflection layer is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum oxynitride, magnesium fluoride, lithium fluoride, ITO, and zinc oxide, with a thickness of 10 to 200 nm.

[0057] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0058] The beneficial effects of the present invention are as follows: In the method for preparing an HBC solar cell provided by the present invention, the intrinsic silicon-containing thin film in the first region is converted into a second doped polysilicon layer by laser, and the second-type doped silicon-containing thin film is converted into a third doped polysilicon layer. Compared with the prior art, the preparation method of the present invention omits the steps of additionally preparing a dielectric layer, or a dielectric layer and a sacrificial layer when preparing the intrinsic silicon-containing thin film and the second-type doped silicon-containing thin film, as well as the multi-channel cleaning process after laser film opening. Therefore, the method for preparing an HBC solar cell of the present invention can effectively simplify the preparation process of the HBC solar cell, reduce the manufacturing cost, and is beneficial to the popularization of the HBC solar cell. And the present invention only needs to use low-energy laser to change the doping type of the film layer, and does not need to use the high-energy laser used in the manufacturing process of the prior art HBC solar cell. Therefore, the laser damage to the battery during the manufacturing process can be reduced, and the photoelectric conversion efficiency of the HBC solar cell can be improved. Description of the Drawings

[0059] Figure 1 It is a flowchart of the method for preparing an HBC solar cell according to Embodiment 1 of the present invention;

[0060] Figure 2 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention;

[0061] Figure 3 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Step 1;

[0062] Figure 4 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Step 1 and Step 2;

[0063] Figure 5 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Steps 1 - 3;

[0064] Figure 6 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Steps 1 - 4;

[0065] Figure 7 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Steps 1 - 5;

[0066] Figure 8 It is a schematic structural diagram of the HBC solar cell according to Embodiment 2 of the present invention after Steps 1 - 6;

[0067] Figure 9Schematic diagram of the HBC solar cell of Embodiment 2 of the present invention after steps 1 - 7;

[0068] Figure 10 Schematic diagram of the HBC solar cell of Embodiment 2 of the present invention after steps 1 - 8;

[0069] Figure 11 Schematic diagram of the HBC solar cell of Embodiment 2 of the present invention after steps 1 - 9.

[0070] Description of reference numerals: 1 - silicon substrate; 1a - first surface; 1b - second surface; 2 - tunneling oxide layer; 3 - first doped polysilicon layer; 4 - dielectric layer; 5 - intrinsic silicon - containing film; 6 - second - type doped silicon - containing film; 7 - second doped polysilicon layer; 8 - third doped polysilicon layer; 9 - passivation layer; 10 - antireflection layer; 11 - conductive thin - film layer; 12 - first metal electrode; 13 - second metal electrode; A - first region; B - second region; C - crossover region. Detailed implementation manners

[0071] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0072] It should be noted that in the claims and the description of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one" does not exclude the existence of another identical element in the process, method, article or device including the element.

[0073] Embodiment 1

[0074] As Figure 1 shown, this embodiment discloses a method for manufacturing an HBC solar cell, which includes the following steps:

[0075] Step 1 (S1): Select a silicon substrate having opposite first and second surfaces 1a and 1b. The second surface 1b includes a first region, a second region, and an intersection region disposed between the first and second regions. The first region, the second region, and the intersection region are arranged alternately, and the intersection region isolates the first region and the second region. Refer to Figure 2 and Figure 3 .

[0076] Step 2 (S2): Sequentially form a tunneling oxide layer 2, a first doped polysilicon layer 3, and a dielectric layer 4 on the second surface 1b of the silicon substrate 1. The first doped polysilicon layer 3 is doped with a first type of doping atom. Taking the first doped polysilicon layer 3 as an n-type doped polysilicon layer as an example, doping with a first type of doping atom means doping with an n-type doping atom, such as a phosphorus atom. As Figure 4 shown, the tunneling oxide layer 2 includes silicon oxide and has a thickness of 0.5 - 3 nm, for example, it can be 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, or 3 nm, etc. The thickness of the first doped polysilicon layer 3 is 30 - 300 nm, for example, it can be 30 nm, 100 nm, 150 nm, 200 nm, 250 nm, or 300 nm, etc.; the dielectric layer 4 is one or more of silicon oxide, silicon nitride, and silicon oxynitride.

[0077] Step 3 (S3): Remove the dielectric layer 4, the first doped polysilicon layer 3, and the tunneling oxide layer 2 on the second region. Refer to Figure 5 .

[0078] Specifically, remove the dielectric layer 4 on the second region, and polish and texture the exposed surface of the silicon substrate 1 to remove the first doped polysilicon layer 3 and the tunneling oxide layer 2 on the second region, so that the first surface 1a of the silicon substrate 1 and the second region of the second surface 1b expose the silicon substrate 1 and form a textured surface structure; or remove the dielectric layer 4, the first doped polysilicon layer 3, and the tunneling oxide layer 2 on the second region, and polish and texture the exposed surface of the silicon substrate 1, so that the first surface 1a of the silicon substrate 1 and the second region of the second surface 1b expose the silicon substrate 1 and form a textured surface structure. Refer to Figure 5 .

[0079] Step 4 (S4): Remove the dielectric layer 4 on the first region and the intersection region. Specifically, use a cleaning agent to clean and remove the dielectric layer 4 on the first region and the intersection region of the silicon substrate 1.

[0080] Step 5 (S5): Sequentially form an intrinsic silicon-containing film 5 and a second type doped silicon-containing film 6 on the second surface 1b. The second type doped silicon-containing film 6 is doped with a second type of doping atom, and the conductivity of the second type of doping atom is opposite to that after doping with the first type of doping atom.

[0081] For example, the second-type doped silicon-containing thin film 6 can be a p-type doped silicon-containing thin film. The second-type doped silicon-containing thin film 6 is doped with second-type doping atoms, i.e., p-type doping atoms, and the conductivity after doping with the second-type doping atoms is opposite to that after doping with the first-type doping atoms. A passivation layer 9 and an antireflection layer 10 are sequentially formed on the first surface 1a of the silicon substrate 1. As Figure 7 shown, among them, the intrinsic silicon-containing thin film 5 uses the following materials: microcrystalline silicon, nanocrystalline silicon, amorphous silicon, silicon oxide, silicon carbide; the intrinsic silicon-containing thin film (5) adopts any of the following forms:

[0082] Single-layer thin film: a single-layer structure formed by one material, with the same properties throughout the layer;

[0083] Multi-layer thin film: composed of multiple different materials, with different properties for each layer;

[0084] Stacked thin film: formed by stacking several materials in a specific order, with each layer cooperating with each other;

[0085] Hybrid thin film: a single-layer structure formed by mixing several different materials.

[0086] The second-type doped silicon-containing thin film 6 uses the following materials: microcrystalline silicon, nanocrystalline silicon, amorphous silicon, silicon oxide or silicon carbide; the second-type doped silicon-containing thin film (6) adopts any of the following forms:

[0087] Single-layer thin film: a single-layer structure formed by one material, with the same properties throughout the layer;

[0088] Multi-layer thin film: composed of multiple different materials, with different properties for each layer;

[0089] Stacked thin film: formed by stacking several materials in a specific order, with each layer cooperating with each other;

[0090] Hybrid thin film: a single-layer structure formed by mixing several different materials.

[0091] A passivation layer 9 and an antireflection layer 10 are sequentially arranged on the first surface 1a along the direction away from the silicon substrate 1. The passivation layer 9 is an intrinsic silicon-containing film, or the passivation layer 9 is a combination of an intrinsic silicon-containing film and a doped silicon-containing film. The thickness of the intrinsic silicon-containing film is 1-15 nm, such as 1 nm, 3 nm, 5 nm, 6 nm, 10 nm or 15 nm, etc. The thickness of the doped silicon-containing film is 1-30 nm, such as 1 nm, 5 nm, 15 nm, 18 nm, 20 nm or 30 nm, etc., or the passivation layer 9 is a doped silicon-containing film; the antireflection layer 10 is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum oxynitride, magnesium fluoride, lithium fluoride, ITO, zinc oxide, and the thickness is 10-200 nm, such as 10 nm, 15 nm, 100 nm, 150 nm or 200 nm, etc.

[0092] Step 6 (S6), the intrinsic silicon-containing film 5 and the second-type doped silicon-containing film 6 in the first region are processed by laser, so that the intrinsic silicon-containing film 5 is converted into a second-doped polysilicon layer 7, and the second-type doped silicon-containing film 6 is converted into a third-doped polysilicon layer 8. Both the second-doped polysilicon layer 7 and the third-doped polysilicon layer 8 are doped with the first-type doping atoms.

[0093] For example, by laser-treating the intrinsic silicon-containing film 5 and the second-type doped silicon-containing film 6 (P-type doped silicon film) in the first region, an n-type doping source is provided by the first-doped polysilicon layer 3 (n-type doped polysilicon layer), such as Figure 8 shown, the intrinsic silicon-containing film 5 is converted into a second-doped polysilicon layer 7 (n-type doped polysilicon layer), the second-type doped silicon-containing film 6 (P-type doped silicon film) is converted into a third-doped polysilicon layer 8 (n-type doped polysilicon layer), and both the second-doped polysilicon layer 7 and the third-doped polysilicon layer 8 are doped with the first-type doping atoms. This process mainly uses the energy of the laser to redistribute the phosphorus atoms in the first-doped polysilicon layer 3, that is, the phosphorus atoms in the first-doped polysilicon layer 3 diffuse into the outward intrinsic silicon-containing film 5 and the second-type doped silicon-containing film 6 under the heat treatment of the laser, and the donor doping of the formed phosphorus atoms is all converted into n-type doping.

[0094] The preparation method of the HBC solar cell in this embodiment converts the intrinsic silicon-containing thin film in the first region into a second doped polysilicon layer and converts the second-type doped silicon-containing thin film into a third doped polysilicon layer by laser. Compared with the prior art, the preparation method of the present invention omits the steps of additionally preparing a dielectric layer, or a dielectric layer and a sacrificial layer when preparing the intrinsic silicon-containing thin film and the second-type doped silicon-containing thin film, as well as the multi-step cleaning process after laser film opening. Therefore, the preparation method of the HBC solar cell of the present invention can effectively simplify the preparation process of the HBC solar cell, reduce the manufacturing cost, and is conducive to the popularization of the HBC solar cell. And the method of this embodiment only needs to use low-energy laser to change the doping type of the film layer, and does not need to use the high-energy laser used in the manufacturing process of the prior art HBC solar cell. Therefore, the laser damage to the battery during the manufacturing process can be reduced, and the photoelectric conversion efficiency of the HBC solar cell can be improved.

[0095] In step S6, the parameters of the laser treatment include: using ultraviolet laser or green light for treatment, and the pulse width of the ultraviolet laser or green light is at least one of picosecond and femtosecond, and the power is 1-100W.

[0096] Further, in this embodiment, the doping concentration of the first doped polysilicon layer 3 is not less than that of the second doped polysilicon layer 7, and the doping concentration of the second doped polysilicon layer 7 is not less than that of the third doped polysilicon layer 8. The doping concentration of the first doped polysilicon layer 3 is not greater than 8×10 20 atoms / cm 3 . This is because the doped atoms in the first doped polysilicon layer diffuse into the second doped polysilicon layer 7 and the third doped polysilicon layer 8. And by setting the doping concentrations of the three film layers in this way, the light incident from the front can be more reflected into the silicon substrate 1 when passing through the first doped polysilicon layer 3, further increasing the light absorption efficiency of the HBC solar cell.

[0097] Further, the preparation method of the HBC solar cell in this embodiment further includes the following steps after step 6 (S6):

[0098] Step 7 (S7), forming a conductive thin film layer 11 on the second surface 1b of the silicon substrate 1. As Figure 9 shown, wherein, the conductive thin film layer 11 is a multi-layer or stacked layer or mixture of one or more doped metal oxides or metal nitrides. The metal oxide can be indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium nitride, and the metal nitride can be titanium nitride. Its doping elements can be indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0099] Step 8 (S8), removing partial conductive thin film layers 11 in the first region, partial conductive thin film layers 11 in the second region, and all the conductive thin films 11 in the crossover region to form effective insulation between the first region and the second region.

[0100] In this embodiment, the HBC solar cell preparation method including the above steps can replace the traditional laser grooving method for insulation, further simplify the HBC solar cell preparation process, and at the same time further reduce laser damage during the process.

[0101] Further, the HBC solar cell preparation method of this embodiment further includes the following steps after step S8:

[0102] Step 9 (S9), fabricating a first metal electrode 12 and a second metal electrode 13 electrically connected to the conductive thin film layer 11 on the first region and the second region of the silicon substrate 1 respectively.

[0103] In this embodiment, setting the first metal electrode 12 and the second metal electrode 13 ensures that the solar cell can collect and transmit photo-generated current more effectively, thereby further improving the photoelectric conversion efficiency.

[0104] Further, the HBC solar cell preparation method of this embodiment further includes the following steps in step 1 (S1):

[0105] S11, performing texturing and polishing treatment or polishing treatment on the silicon substrate 1 to form a pyramid base structure on the first surface 1a and the second surface 1b. It should be noted that the pyramid base structure can be a structure formed after polishing the pyramidal structure of the textured surface, or a regular or irregular structure protruding from the surface formed by direct polishing.

[0106] In this embodiment, by adopting the HBC solar cell preparation method including the above steps, forming the pyramid base structure is beneficial to forming the tunneling oxide layer 2 on the second surface 1b. And by forming a tiny textured pyramid base structure on the silicon substrate surface, the scattering and reflection of sunlight can be increased, thereby increasing the path length of light in the silicon material and improving the light absorption rate. A smooth silicon surface will cause higher reflection loss, and the pyramid base treatment can significantly reduce the reflectivity of sunlight and improve the photoelectric conversion efficiency of the solar cell.

[0107] Further, in step 3 (S3) of the HBC solar cell preparation method of this embodiment, the dielectric layer on the second region is removed by the method of laser film opening. Laser film opening can achieve highly precise film layer removal, only treating specific regions without affecting other parts.

[0108] And in step 4 (S4), the cleaning agent is a solvent made of hydrofluoric acid because hydrofluoric acid is a very effective chemical reagent for removing silicon oxides. It can quickly and thoroughly dissolve the oxide layer of silicon. Moreover, hydrofluoric acid has a high selectivity for silicon and its oxides, and can remove the surface oxides without affecting the silicon substrate itself. Hydrofluoric acid can smooth the silicon surface, reduce surface defects, and contribute to improving the photoelectric conversion efficiency of solar cells.

[0109] Furthermore, in the method for manufacturing an HBC solar cell of this embodiment, in step 8 (S8), by printing an etching paste on partial regions of the first region, partial regions of the second region, and the cross region, a partial conductive thin film layer 11 in the first region, a partial conductive thin film layer 11 in the second region, and all of the conductive thin film 11 in the cross region are etched and removed. In this embodiment, using the printed etching paste can achieve very precise pattern transfer, only removing the part of the conductive thin film layer that needs to be removed without affecting other regions.

[0110] Embodiment 2

[0111] As Figures 2 - 11 shown, this embodiment discloses an HBC solar cell, which is prepared by using the method for an HBC solar cell disclosed in Embodiment 1. The HBC solar cell of this embodiment includes: a silicon substrate 1 having opposite first surface 1a and second surface 1b, and the second surface 1b includes a first region, a second region, and a cross region provided between the first region and the second region;

[0112] A tunneling oxide layer 2 disposed on the first region of the second surface 1b in sequence along a direction away from the silicon substrate 1, and a first doped polysilicon layer 3, a second doped polysilicon layer 7, and a third doped polysilicon layer 8 all doped with first-type doping atoms, and the tunneling oxide layer 2 and the first doped polysilicon layer 3 extend to the cross region;

[0113] An intrinsic silicon-containing film 5 disposed on the second region of the second surface 1b in sequence along a direction away from the silicon substrate 1 and a second-type doped silicon-containing film 6 doped with second-type doping atoms, and the intrinsic silicon-containing film 5 and the second-type doped silicon-containing film 6 extend to the side of the first doped polysilicon layer 3 facing away from the silicon substrate 1 in the cross region, and the conductive types of the first-type doping atoms and the second-type doping atoms are opposite.

[0114] When the HBC solar cell of this embodiment is produced and prepared, the preparation process can be effectively simplified and the manufacturing cost of itself can be reduced. And the HBC solar cell of this embodiment does not need to use high-energy lasers used in the manufacturing process of existing technology HBC solar cells during the manufacturing process. Therefore, the laser damage to the battery during the manufacturing process can be reduced, and the photoelectric conversion efficiency of the HBC solar cell can be improved.

[0115] Furthermore, the HBC solar cell of this embodiment further includes a conductive thin film layer 11, which is disposed on one side surface of the third doped polysilicon layer 8 away from the silicon substrate 1 and one side surface of the second-type doped silicon-containing thin film 6 away from the silicon substrate 1, and the conductive thin film 11 is disconnected in the cross region.

[0116] The projected area of the conductive thin film layer 11 on the silicon substrate 1 in the first region is smaller than the projected area of the second doped polysilicon layer 7 or the third doped polysilicon layer 8 on the silicon substrate 1; the projected area of the conductive thin film layer 11 on the silicon substrate 1 in the second region is smaller than the projected area of the intrinsic silicon-containing thin film 5 or the second-type doped silicon-containing thin film 6 on the silicon substrate 1 in the second region.

[0117] When the HBC solar cell of this embodiment is produced and prepared, it can no longer use the traditional laser grooving method for insulation, which can further simplify its preparation process and further reduce laser damage during the process. Because this solution uses laser to change the doping type of the film layer to replace the traditional method of removing the film layer by laser, and the laser energy used in this solution is much smaller.

[0118] Moreover, in this embodiment, the doping concentration of the first doped polysilicon layer 3 is not less than the doping concentration of the second doped polysilicon layer 7, and the doping concentration of the second doped polysilicon layer 7 is not less than the doping concentration of the third doped polysilicon layer 8. Thus, it is formed by the diffusion of the doping atoms in the first doped polysilicon layer into the second doped polysilicon layer 7 and the third doped polysilicon layer 8. And by setting the doping concentrations of the three film layers in this way, the light incident from the front can be more reflected into the silicon substrate 1 when passing through the first doped polysilicon layer 3, further increasing the light absorption efficiency of the HBC solar cell.

[0119] Furthermore, the HBC solar cell of this embodiment further includes a first metal electrode 12 and a second metal electrode 13.

[0120] The first metal electrode 12 is disposed on one side surface of the conductive thin film layer 11 in the first region away from the silicon substrate 1.

[0121] The second metal electrode 13 is disposed on one side surface of the conductive thin film layer 11 in the second region away from the silicon substrate 1.

[0122] The HBC solar cell of this embodiment is provided with the first metal electrode 12 and the second metal electrode 13, which can more effectively collect and transport the photo-generated current, thereby further improving the photoelectric conversion efficiency.

[0123] For the HBC solar cell of this embodiment, the conductive type of the silicon substrate 1 is one of n-type or p-type, preferably n-type.

[0124] The tunneling oxide layer 2 is silicon oxide with a thickness of 0.5 to 3 nm, for example, it can be 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm or 3 nm.

[0125] The first doped polysilicon layer 3 has a thickness of 30 to 300 nm, for example, it can be 30 nm, 100 nm, 150 nm, 200 nm, 250 nm or 300 nm, etc.

[0126] The dielectric layer 4 is one or more of silicon oxide, silicon nitride or silicon oxynitride.

[0127] The intrinsic silicon-containing film 5 is a single layer or a multi-layer with the same performance or a stack or mixture of several of the following film layers: microcrystalline, nano, amorphous silicon, silicon oxide or silicon carbide, etc. That is, the intrinsic silicon-containing film 5 uses the following materials: microcrystalline silicon, nano-silicon, amorphous silicon, silicon oxide, silicon carbide; the intrinsic silicon-containing film 5 adopts any of the following forms:

[0128] Single-layer film: A single-layer structure formed by one material, with the same performance throughout the layer;

[0129] Multi-layer film: Composed of multiple layers of different materials, with different performances for each layer;

[0130] Stacked film: Stacked by several materials in a specific order, with each layer cooperating with each other;

[0131] Mixed film: A single-layer structure formed by mixing several different materials.

[0132] The second type of doped silicon-containing film 6 is a single layer or a multi-layer with the same performance or a stack or mixture of several of the following film layers: microcrystalline, nano, amorphous silicon, silicon oxide or silicon carbide, etc. That is, the second type of doped silicon-containing film 6 uses the following materials: microcrystalline silicon, nano-silicon, amorphous silicon, silicon oxide or silicon carbide; the second type of doped silicon-containing film 6 adopts any of the following forms:

[0133] Single-layer film: A single-layer structure formed by one material, with the same performance throughout the layer;

[0134] Multi-layer film: Composed of multiple layers of different materials, with different performances for each layer;

[0135] Stacked film: Stacked by several materials in a specific order, with each layer cooperating with each other;

[0136] Mixed film: A single-layer structure formed by mixing several different materials.

[0137] The passivation layer 9 is an intrinsic silicon-containing film, or the passivation layer 9 is a combination of an intrinsic silicon-containing film and a doped silicon-containing film. The thickness of the intrinsic silicon-containing film is 1 to 15 nm, such as 1 nm, 3 nm, 5 nm, 6 nm, 10 nm, or 15 nm, etc. The thickness of the doped silicon-containing film is 1 to 30 nm, such as 1 nm, 5 nm, 15 nm, 18 nm, 20 nm, or 30 nm, etc. Or the passivation layer 9 is a doped silicon-containing film.

[0138] The antireflection layer 10 is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum oxynitride, magnesium fluoride, lithium fluoride, indium tin oxide, and zinc oxide, and the thickness is 10 to 200 nm, such as 10 nm, 15 nm, 100 nm, 150 nm, or 200 nm, etc.

[0139] The conductive thin film layer 11 is a multi-layer or stacked layer or mixture of one or more doped metal oxides, or the conductive thin film layer 11 is a multi-layer or stacked layer or mixture of one or more doped metal nitrides. The metal oxides are one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide, and titanium nitride. The metal nitride is titanium nitride, and the doping elements include one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0140] The first metal electrode 12 or the second metal electrode 13 is a stacked layer formed by one or several of a silver electrode, a silver alloy electrode, a copper electrode, a copper alloy electrode, and a multi-layer electrode of nickel, copper, and silver.

Claims

1. A method for preparing a HBC solar cell, characterized in that: The following steps are involved: S1. Selecting a silicon substrate having a first surface (1a) and a second surface (1b) opposite to each other, wherein the second surface (1b) includes a first region, a second region, and an intersection region between the first region and the second region; S2, forming a tunneling oxide layer (2), a first doped polysilicon layer (3) and a dielectric layer (4) in sequence on the second surface (1b), wherein the first doped polysilicon layer (3) is doped with first-type doping atoms; S3, removing the dielectric layer (4), the first doped polysilicon layer (3) and the tunneling oxide layer (2) on the second region; S4, removing the dielectric layer (4) on the first area and the intersection area; S5, sequentially forming an intrinsic silicon-containing film (5) and a second-type doped silicon-containing film (6) on the second surface (1b), wherein the second-type doped silicon-containing film (6) is doped with second-type doping atoms, and the conductive properties of the second-type doping atoms after doping are opposite to those of the first-type doping atoms; S6. Using laser to process the intrinsic silicon-containing film (5) and the second-type doped silicon-containing film (6) in the first region, so that the intrinsic silicon-containing film (5) is converted into a second doped polysilicon layer (7), and the second-type doped silicon-containing film (6) is converted into a third doped polysilicon layer (8), and both the second doped polysilicon layer (7) and the third doped polysilicon layer (8) are doped with the first-type doping atoms.

2. The method according to claim 1, characterized in that In step S6, the parameters of the laser processing include: using ultraviolet laser or green light for processing, the pulse width of the ultraviolet laser or green light is at least one of picosecond and femtosecond, and the power is 1-100W.

3. The method according to claim 1, characterized in that The doping concentration of the first doped polysilicon layer is not less than the doping concentration of the second doped polysilicon layer, and the doping concentration of the second doped polysilicon layer is not less than the doping concentration of the third doped polysilicon layer, and the doping concentration of the first doped polysilicon layer is not greater than 8×10 20 atoms / cm 3 .

4. The method according to claim 1, characterized in that After step S6, the method further includes the following steps: S7, forming a conductive film layer (11) on the second surface (1b); S8, removing part of the conductive film layer (11) in the first region, part of the conductive film layer (11) in the second region, and all of the conductive film (11) in the intersection region.

5. The method according to claim 4, characterized in that After step S8, the method further includes the following steps: S9, respectively manufacturing a first metal electrode (12) and a second metal electrode (13) electrically connected to the conductive film layer (11) on the first region and the second region; Preferably, step S8 comprises: printing etching slurry on a portion of the first area, a portion of the second area and an intersection area to etch and remove a portion of the conductive film layer (11) in the first area, a portion of the conductive film layer (11) in the second area and all of the conductive film (11) in the intersection area.

6. The method according to claim 1, characterized in that In step S1, the following steps are also included: S11, performing a texturing and polishing process, or a polishing process, on the silicon substrate (1) to form a tower base structure on the first surface (1a) and the second surface (1b); Preferably, step S3 comprises: removing the dielectric layer (4) on the second region, and performing polishing and texturing on the exposed surface of the silicon substrate (1), and removing the first doped polysilicon layer (3) and the tunneling oxide layer (2) on the second region, so that the second region of the first surface (1a) and the second surface (1b) of the silicon substrate (1) expose the silicon substrate (1) and form a texturing surface structure; or removing the dielectric layer (4), the first doped polysilicon layer (3) and the tunneling oxide layer (2) on the second region, and performing polishing and texturing on the exposed surface of the silicon substrate (1), so that the second region of the first surface (1a) and the second surface (1b) of the silicon substrate (1) expose the silicon substrate (1) and form a texturing surface structure; Preferably, in step S3, the dielectric layer (4) on the second region is removed by laser film opening method; Preferably, in step S4, the dielectric layer (4) is removed using a solvent made of hydrofluoric acid; Preferably, the step S5 further comprises: sequentially forming a passivation layer (9) and an anti-reflection layer (10) on the first surface (1a); Preferably, the dielectric layer (4) is one or more of silicon oxide, silicon nitride, and silicon oxynitride.

7. A HBC solar cell, characterized in that: include: A silicon substrate (1) having a first surface (1a) and a second surface (1b) opposite to each other, wherein the second surface (1b) comprises a first region, a second region, and an intersection region between the first region and the second region; A tunneling oxide layer (2), a first doped polysilicon layer (3), a second doped polysilicon layer (7) and a third doped polysilicon layer (8) all doped with first-type doping atoms, which are sequentially arranged in a direction away from the silicon substrate (1) in a first region of the second surface (1b), and the tunneling oxide layer (2) and the first doped polysilicon layer (3) extend to the intersection region; An intrinsic silicon-containing film (5) and a second-type doped silicon-containing film (6) doped with second-type doping atoms are sequentially arranged in a second region of the second surface (1b) along a direction away from the silicon substrate (1), and the intrinsic silicon-containing film (5) and the second-type doped silicon-containing film (6) extend to a side of the first doped polysilicon layer (3) in the intersection region that is away from the silicon substrate (1), and the first-type doping atoms and the second-type doping atoms have opposite conductivity types.

8. The HBC solar cell according to claim 7, characterized in that: Also includes: A conductive film layer (11) is arranged on a side surface of the third doped polysilicon layer (8) facing away from the silicon substrate (1) and a side surface of the second type doped silicon-containing film (6) facing away from the silicon substrate (1), and the conductive film (11) is disconnected in the intersection area.

9. The HBC solar cell according to claim 7, characterized in that: The projected area of ​​the conductive film layer (11) on the first region on the silicon substrate (1) is smaller than the projected area of ​​the second doped polysilicon layer (7) or the third doped polysilicon layer (8) on the silicon substrate (1); And / or, the projected area of ​​the conductive film layer (11) on the second region on the silicon substrate (1) is smaller than the projected area of ​​the intrinsic silicon-containing film (5) or the second-type doped silicon-containing film (6) on the second region on the silicon substrate (1).

10. The HBC solar cell according to claim 7, characterized in that: The doping concentration of the first doped polysilicon layer (3) is not less than the doping concentration of the second doped polysilicon layer (7), and the doping concentration of the second doped polysilicon layer (7) is not less than the doping concentration of the third doped polysilicon layer (8), and the doping concentration of the first doped polysilicon layer is not greater than 8×10 20 atoms / cm 3 ; Preferably, it also includes: A first metal electrode (12) is arranged on a side surface of the conductive film layer (11) at the first region that is away from the silicon substrate (1); A second metal electrode (13) is arranged on a side surface of the conductive film layer (11) at the second region that is away from the silicon substrate (1); Preferably, the conductivity type of the silicon substrate (1) is one of n-type or p-type; And / or, the tunneling oxide layer (2) is silicon oxide with a thickness of 0.5 to 3 nm; And / or, the thickness of the first doped polysilicon layer (3) is 30 to 300 nm; And / or, the intrinsic silicon-containing film (5) is made of the following materials: at least one of microcrystalline silicon, nano-silicon, amorphous silicon, silicon oxide, and silicon carbide; the intrinsic silicon-containing film (5) is in any of the following forms: Single-layer film: A single-layer structure formed by one material with the same performance throughout the layer; Multilayer film: composed of multiple layers of different materials, each layer has different properties; Laminated film: Made of several materials stacked in a specific order, with each layer working in harmony with the other; Hybrid film: a single-layer structure formed by mixing several different materials; And / or, the second-type doped silicon-containing film (6) is made of the following materials: microcrystalline silicon, nano-silicon, amorphous silicon, silicon oxide or silicon carbide; the second-type doped silicon-containing film (6) is in any of the following forms: Single-layer film: A single-layer structure formed by one material with the same performance throughout the layer; Multilayer film: composed of multiple layers of different materials, each layer has different properties; Laminated film: Made of several materials stacked in a specific order, with each layer working in harmony with the other; Hybrid film: a single-layer structure formed by mixing several different materials; And / or, the conductive film layer (11) is a multilayer or stacked layer or a mixture of one or more doped metal oxides, or the conductive film layer (11) is a multilayer or stacked layer or a mixture of one or more doped metal nitrides, the metal oxides include one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium nitride, the metal nitride includes titanium nitride, and its doping elements include one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine; And / or, the first metal electrode (12) or the second metal electrode (13) is a stack formed by one or more of a silver electrode, a silver alloy electrode, a copper electrode, a copper alloy electrode, a multilayer electrode composed of nickel, copper and silver; And / or, a passivation layer (9) and an anti-reflection layer (10) are sequentially arranged on the first surface (1a) along a direction away from the silicon substrate (1), preferably, the passivation layer (9) is an intrinsic silicon-containing film, or the passivation layer (9) is a combination of an intrinsic silicon-containing film and a doped silicon-containing film, wherein the thickness of the intrinsic silicon-containing film is 1 to 15 nm, and the thickness of the doped silicon-containing film is 1 to 30 nm, or the passivation layer (9) is a doped silicon-containing film, preferably, the anti-reflection layer (10) is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum nitride, magnesium fluoride, lithium fluoride, indium tin oxide, and zinc oxide, and the thickness is 10 to 200 nm.

Images