An IBC solar cell structure and its preparation process

Abstract

The present invention discloses an IBC solar cell structure, which includes an antireflection layer, a front passivation film layer, a p-type diffusion layer, an n-type monocrystalline silicon base layer, a back passivation film layer, an organic heterojunction layer, a back conductive protection layer, and a back electrode, which are sequentially stacked; a patterned organic heterojunction layer is formed on the back surface of the n-type monocrystalline silicon base layer, the organic heterojunction layer includes a p-type organic heterojunction layer and an n-type organic heterojunction layer, and a space isolation region is formed between the p-type organic heterojunction layer and the n-type organic heterojunction layer; the present invention also correspondingly discloses a preparation process for the above IBC solar cell structure. By moving the contact surface between the organic substance and the monocrystalline silicon to the back surface of the battery, the present invention ensures the formation of a uniform and high-quality organic hybrid heterojunction film layer, and the front surface adopts an alkaline textured pyramid texture structure, which can greatly improve the optical performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a low-cost organic / silicon hybrid IBC solar cell structure and a preparation process thereof. Background Art

[0002] A solar cell is a semiconductor device that directly converts the light energy of the sun into electrical energy. Utilizing the renewable resource of light energy, solar cells have broad development prospects in the current situation of energy shortage.

[0003] There are various types of solar cells. Among them, IBC (Interdigitated back contact) solar cells have attracted more and more attention from industry insiders due to their advantages such as high conversion efficiency, low series resistance, simplified interconnection technology, and good appearance, and have become one of the more advanced high-efficiency battery technologies in the field of solar cell technology.

[0004] The general process flow for fabricating a conventional IBC solar cell is roughly: cleaning - surface texturing - double-sided diffusion doping - removing the glass layer - screen printing the blocking layer - etching to form the first conductive finger region - diffusion to form the second conductive finger region - preparing an antireflection layer on the front side - preparing a back passivation layer on the back side - screen printing the first electrode and the second electrode - sintering - laser sintering. In the actual production process, there are many technical details and corresponding operation steps for fabricating IBC solar cells. The numerous steps and complex operations result in low production efficiency of IBC solar cells and high production costs, which pose difficulties to the development of IBC solar cells.

[0005] The IBC back contact solar cell structure forms an interdigitated doped n-type doped region and p-type doped region through backside patterning doping. Due to the requirement of this patterning doping, multiple masking processes are required in terms of process implementation, the preparation process is complex, and the cost is extremely high. On the other hand, for the currently used organic-inorganic hybrid heterojunction solar cells, their contact surfaces are generally flat. This flat structure causes a large amount of optical reflection loss. Then, when a textured surface structure is adopted, due to the poor wettability between the organic material and the inorganic material (usually silicon crystal material), the organic material cannot form a uniform film layer on the silicon crystal surface.

[0006] Therefore, there is an urgent need for a preparation process with low cost and capable of overcoming a large amount of optical reflection loss caused by the interface. Summary of the Invention

[0007] To solve the problems of the prior art, on the one hand, the present invention provides an IBC solar cell structure, including an antireflection layer, a front passivation film layer, a p-type diffusion layer, an n-type single-crystalline silicon base layer, a back passivation film layer, an organic heterojunction layer, a back conductive protection layer, and a back electrode that are sequentially stacked.

[0008] The n-type monocrystalline silicon base layer includes a front side and a back side, and the front side is configured as a matte surface structure; the front side includes a p-type diffusion layer and a front p+-type emitter region is formed in the p-type diffusion layer; a patterned organic heterojunction layer is formed on the back side, the organic heterojunction layer includes a p-type organic heterojunction layer and an n-type organic heterojunction layer, and a space isolation region is formed between the p-type organic heterojunction layer and the n-type organic heterojunction layer; the organic heterojunction layer is flatly attached to the back side passivation film layer.

[0009] As a further improvement of the embodiment of the present invention, the antireflection layer is one or more of silicon oxide, silicon nitride, silicon oxynitride, and magnesium fluoride.

[0010] As a further improvement of the embodiment of the present invention, the front side passivation film layer includes a stacked alumina layer and a silicon oxide layer, the alumina layer is attached to the antireflection layer, and the silicon oxide layer is attached to the p-type diffusion layer.

[0011] As a further improvement of the embodiment of the present invention, the p-type diffusion layer is formed by boron diffusion or boron ion implantation.

[0012] As a further improvement of the embodiment of the present invention, the back side conductive protection layer is configured as a transparent conductive TCO protection layer, and the TCO is selected from one or more mixtures of ZnO, In2O3, Ga2O3, TiO2, and ZrO2.

[0013] On the other hand, the present invention further discloses a preparation process for an IBC solar cell structure, and the preparation process includes the following steps:

[0014] S1. Texturize the front side and the back side of the n-type monocrystalline silicon wafer to prepare a pyramid-shaped matte surface structure;

[0015] S2. Perform boron diffusion on the front side of the n-type monocrystalline silicon wafer to form a p layer, and perform local doping on the front side of the n-type monocrystalline silicon wafer to form a front pn junction emitter region;

[0016] S3. Etch and polish the back side of the n-type monocrystalline silicon wafer with an acid or alkali solution to remove the back side diffusion layer and the side conductive channel;

[0017] S5. Perform thermal oxidation on the n-type monocrystalline silicon wafer in an oxidation furnace to form a silicon oxide layer on the front side;

[0018] S6. Deposit a passivation antireflection layer on the front side;

[0019] S7. Clean the back side of the n-type monocrystalline silicon wafer with an acid solution;

[0020] S8. Perform thermal oxidation annealing on the back surface and deposit a silicon oxide passivation layer on the back surface;

[0021] S9. Prepare a p-type organic heterojunction film layer on the back surface;

[0022] S10. Prepare an n-type heterojunction film layer on the back surface;

[0023] S11. Deposit a TCO conductive protection layer on the back surface after annealing.

[0024] S12. Prepare a spatial isolation groove to spatially isolate the p-type organic heterojunction film layer and the n-type heterojunction film layer on the back surface;

[0025] S13. Prepare a back electrode.

[0026] As a further improvement of the embodiment of the present invention, in the step S6, the passivation and antireflection layer is a stack of alumina and silicon nitride.

[0027] As a further improvement of the embodiment of the present invention, in the step S7, the specific process of cleaning the back surface of the n-type monocrystalline silicon wafer with an acid solution includes using HF to clean the back surface to remove the silicon oxide, sputtered alumina and silicon nitride on the back surface.

[0028] As a further improvement of the embodiment of the present invention, in the step S9, the p-type organic heterojunction film layer is a PEDOT:PSS material layer formed by printing, spraying, spin coating or inkjet printing; in the step S10, the n-type organic heterojunction film layer is a PCBM layer formed by printing, spraying, spin coating or inkjet printing.

[0029] As a further improvement of the embodiment of the present invention, in the step S12, the specific method of preparing the spatial isolation groove is to form the spatial isolation groove by laser scribing, mechanical scribing or chemical etching.

[0030] The present invention has the following beneficial effects:

[0031] 1. In the present invention, the contact surface is moved to the back surface of the battery to ensure the formation of a uniform and high-quality organic hybrid heterojunction film layer, while the front surface adopts an alkaline-textured pyramid texture structure, which can greatly improve the optical performance of the battery, overcoming the defect that if the contact surface is a textured surface during the preparation process of the organic layer, the deposition of the organic layer will be uneven and the overall electrical performance will be very poor;

[0032] 2. The present invention moves the organic film layer to the back surface of the battery, and only the penetrating long-wave solar light reaches the organic film layer, so the lifespan of the organic film layer can be greatly improved, overcoming the problem in the prior art that because the organic layer is exposed to solar light for a long time, it will cause performance degradation such as degradation of the organic layer, resulting in poor reliability and weather resistance of the organic hybrid solar cell;

[0033] 3. IBC cells require the formation of cross-arranged p-type and n-type doped regions on the back surface. Therefore, multiple masking, diffusion, cleaning and other processes are used to achieve this process. The manufacturing process is complex and the cost is extremely high. The present invention forms a patterned p-type heterojunction region on the back surface of the cell by printing and spin-coating an organic film layer, and without high temperature, greatly reducing the difficulty of back surface patterning doping, which is a low-cost IBC solar cell manufacturing solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 It is a schematic diagram of an IBC solar cell structure provided by an embodiment of the present invention;

[0036] The examples in the figure are shown as: 1 - antireflection layer; 2 - front passivation film layer; 21 - alumina layer; 22 - silicon oxide layer; 3 - p-type diffusion layer; 4 - n-type single crystal silicon base layer; 5 - back passivation film layer; 6 - organic heterojunction layer; 61 - p-type organic heterojunction layer; 62 - n-type organic heterojunction layer; 7 - back conductive protection layer; 8 - back electrode; 9 - space isolation area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] Embodiment 1

[0039] The embodiment of the present invention provides an IBC solar cell structure, as Figure 1 shown, including an antireflection layer 1, a front passivation film layer 2, a p-type diffusion layer 3, an n-type single crystal silicon base layer 4, a back passivation film layer 5, an organic heterojunction layer 6, a back conductive protection layer 7 and a back electrode 8 which are sequentially stacked;

[0040] Among them, the n-type monocrystalline silicon base layer 4 includes a front side and a back side, and the front side is configured as a matte structure; the front side includes a p-type diffusion layer 3 and a front p+-type emitter region is formed in the p-type diffusion layer 3; a patterned organic heterojunction layer 6 is formed on the back side, and the organic heterojunction layer 6 includes a p-type organic heterojunction layer 61 and an n-type organic heterojunction layer 62, and a space isolation region 9 is formed between the p-type organic heterojunction layer 61 and the n-type organic heterojunction layer 62; the organic heterojunction layer 6 is flatly attached to the back side passivation film layer 5.

[0041] Among them, the antireflection layer 1 is a silicon nitride layer, and in other alternative embodiments, it can also be selected from one or more of silicon oxide, silicon oxynitride, and magnesium fluoride.

[0042] In the embodiment of the present invention, the front side passivation film layer 2 includes an aluminum oxide layer 21 and a silicon oxide layer 22 arranged in a stacked manner. The aluminum oxide layer 21 is attached to the antireflection layer 1, and the silicon oxide layer 22 is attached to the p-type diffusion layer 3.

[0043] Among them, the p-type diffusion layer 3 is formed by boron diffusion or boron ion implantation.

[0044] The back side conductive protection layer 7 is configured as a transparent conductive TCO protection layer, and the TCO is selected from one or more mixtures of ZnO, In2O3, Ga2O3, TiO2, and ZrO2.

[0045] The back side electrode 8 can be one or more of gold, silver, copper, and aluminum.

[0046] Embodiment 2

[0047] The present invention further discloses a preparation process for an IBC solar cell structure, and the preparation process includes the following steps:

[0048] S1. Texturize the front side and the back side of the n-type monocrystalline silicon wafer to prepare a matte structure in the shape of a pyramid;

[0049] S2. Perform boron diffusion on the front side of the n-type monocrystalline silicon wafer to form a p layer, and perform local doping on the front side of the n-type monocrystalline silicon wafer to form a front side pn junction emitter region;

[0050] S3. Etch and polish the back side of the n-type monocrystalline silicon wafer with an acid or a base solution to remove the back side diffusion layer and the side conductive channels;

[0051] S5. Perform thermal oxidation on the n-type monocrystalline silicon wafer in an oxidation furnace to form a silicon oxide layer on the front side;

[0052] S6. Deposit a passivation antireflection layer on the front side;

[0053] S7. Clean the back side of the n-type monocrystalline silicon wafer with an acid solution;

[0054] S8. Perform oxidation annealing on the back surface and deposit a silicon oxide passivation layer on the back surface;

[0055] S9. Prepare a p-type organic heterojunction film layer on the back surface;

[0056] S10. Prepare an n-type heterojunction film layer on the back surface;

[0057] S11. Deposit a TCO conductive protection layer on the back surface after annealing.

[0058] S12. Prepare a spatial isolation groove to spatially isolate the p-type and n-type organic heterojunction film layers on the back surface;

[0059] S13. Prepare the back electrode.

[0060] Among them, the passivation and antireflection layer is a stack of alumina and silicon nitride or a silicon nitride antireflection layer.

[0061] Specifically, in step S7, the cleaning of the back surface of the n-type monocrystalline silicon wafer with an acid solution specifically includes using HF to clean the back surface to remove silicon oxide, deposited alumina, and silicon nitride on the back surface.

[0062] The p-type organic heterojunction film layer in step S9 is a PEDOT:PSS material layer formed by printing, spraying, spin coating, or inkjet printing; the n-type organic heterojunction film layer in step S10 is a PCBM layer formed by printing, spraying, spin coating, or inkjet printing.

[0063] In the embodiment of the present invention, the specific method for preparing the spatial isolation groove in step S12 is to form the spatial isolation groove by laser scribing, mechanical scribing, or chemical etching.

[0064] The present invention has the following beneficial effects:

[0065] 1. In the present invention, the contact surface is moved to the back of the battery, ensuring the formation of a uniform and high-quality organic hybrid heterojunction film layer. The front surface adopts an alkaline-textured pyramid texture structure, which can greatly improve the optical performance of the battery, overcoming the defect that if the contact surface is textured during the preparation of the organic layer, it will cause uneven deposition of the organic layer and thus poor overall electrical performance;

[0066] 2. The present invention moves the organic film layer to the back of the battery, and only the penetrating long-wave solar light reaches the organic film layer. Therefore, the lifespan of the organic film layer can be greatly improved, overcoming the problem in the prior art that because the organic layer is exposed to solar light for a long time, it will cause performance degradation such as degradation of the organic layer, resulting in poor reliability and weather resistance of the organic hybrid solar cell;

[0067] 3. IBC cells require the formation of cross-arranged p-type and n-type doping regions on the back. Therefore, multiple masking, diffusion, cleaning and other processes are used to achieve this process. The preparation process is complex and the cost is extremely high. The present invention forms a patterned p-type heterojunction region on the back of the cell by printing and spin-coating an organic film layer, and does not require high temperature, greatly reducing the difficulty of backside patterning doping, which is a low-cost IBC solar cell preparation solution.

[0068] All of the above optional technical solutions can be combined arbitrarily to form optional embodiments of the present invention, which will not be elaborated here one by one.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An IBC solar cell structure, characterized in that, It includes an antireflection layer, a front passivation film layer, a p-type diffusion layer, an n-type monocrystalline silicon substrate layer, a back passivation film layer, an organic heterojunction layer, a back conductive protection layer, and a back electrode, which are stacked in sequence. The n-type monocrystalline silicon substrate layer includes a front side and a back side. The front side is configured as a textured surface structure. The front side includes a p-type diffusion layer and a front p+-type emitter region is formed in the p-type diffusion layer. A patterned organic heterojunction layer is formed on the back side. The organic heterojunction layer includes a p-type organic heterojunction layer and an n-type organic heterojunction layer. There is a space isolation region formed between the p-type organic heterojunction layer and the n-type organic heterojunction layer. The organic heterojunction layer is flatly attached to the back passivation film layer. The antireflection layer is one or more of silicon oxide, silicon nitride, silicon oxynitride, and magnesium fluoride. The front passivation film layer includes a stacked aluminum oxide layer and a silicon oxide layer. The aluminum oxide layer is attached to the antireflection layer, and the silicon oxide layer is attached to the p-type diffusion layer. The p-type diffusion layer is formed by boron diffusion or boron ion implantation. The back conductive protection layer is configured as a transparent conductive TCO protection layer, and the TCO is selected from one or more mixtures of ZnO, In2O3, Ga2O3, TiO2, and ZrO2.

2. A preparation process for an IBC solar cell structure, characterized in that, The preparation process includes the following steps: S1. Texturize the front and back sides of the n-type monocrystalline silicon wafer to prepare a pyramidal textured surface structure; S2. Perform boron diffusion on the front side of the n-type monocrystalline silicon wafer to form a p layer, and perform local doping on the front side of the n-type monocrystalline silicon wafer to form a front pn junction emitter region; S3. Etch and polish the back side of the n-type monocrystalline silicon wafer with an acid or base solution to remove the back diffusion layer and the side conductive channels; S5. Thermally oxidize the n-type monocrystalline silicon wafer in an oxidation furnace to form a silicon oxide layer on the front side; S6. Deposit a passivation antireflection layer on the front side; S7. Clean the back side of the n-type monocrystalline silicon wafer with an acid solution; S8. Perform oxidation annealing on the back side and deposit a silicon oxide passivation layer on the back side; S9. Prepare a p-type organic heterojunction film layer on the back side; S10. Prepare an n-type organic heterojunction film layer on the back side; S11. Deposit a TCO conductive protection layer on the back side after annealing; S12. Prepare a space isolation groove to isolate the back p-type heterojunction film layer and the n-type heterojunction film layer; S13. Prepare the back electrode. In step S6, the passivation antireflection layer is a stacked layer of aluminum oxide and silicon nitride.

3. The preparation process of the IBC solar cell structure according to claim 2, characterized in that, In step S7, cleaning the back side of the n-type monocrystalline silicon wafer with an acid solution specifically includes cleaning the back surface with HF to remove the back silicon oxide, the deposited aluminum oxide, and silicon nitride.

4. The preparation process of the IBC solar cell structure according to claim 2, characterized in that, In step S9, the p-type organic heterojunction film layer is a PEDOT:PSS material layer formed by printing, spraying, spin coating, or inkjet printing. In step S10, the n-type organic heterojunction film layer is a PCBM layer formed by printing, spraying, spin coating, or inkjet printing.

5. The preparation process of the IBC solar cell structure according to claim 2, characterized in that, In step S12, the specific method for preparing the space isolation groove is to form the space isolation groove by laser scribing, mechanical scribing, or chemical etching.

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