Laminated back contact solar cell structure and preparation method thereof

Abstract

The invention discloses a laminated back contact solar cell structure and a preparation method thereof, the laminated back contact solar cell structure comprises a top cell and a bottom cell; the top cell is a back contact perovskite cell; the bottom cell is a back contact crystalline silicon cell; the top cell is the back contact perovskite cell, the bottom cell is the back contact crystalline silicon cell, and the back contact electrode of the perovskite cell is connected with the back contact electrode of the crystalline silicon cell, so that the positive electrode and the negative electrode of the cell are located in the middle of the laminated cell, and for the solar cell with double-sided power generation, the incident light quantity of the two sides of the cell is more, and the power generation efficiency is improved. And the electrodes cannot be seen on two surfaces, so that the appearance is more attractive. In the invention, ultraviolet and short-wave band light is mainly absorbed by the perovskite cell on the upper layer, and medium-long and long-wave light is almost not absorbed by the doping layer, so that the bottom cell enables one side of the electrode and the doping layer to face upwards, and the influence on light absorption does not need to be considered.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a laminated back-contact solar cell structure and a preparation method thereof. Background Art

[0002] At present, single-junction solar cells have already reached the theoretical limit of efficiency. In order to achieve higher photoelectric conversion efficiency, multi-junction solar cells are the direction of development. Multi-junction solar cells are multiple single-junction solar cells stacked, also called stacked solar cells. At present, perovskite solar cells and crystalline silicon solar cells are single-junction solar cells with high conversion efficiency. Since perovskite solar cells and crystalline silicon solar cells can realize the absorption and utilization of solar cells in different bands respectively, the stacked solar cell of perovskite + crystalline silicon cells is the most promising stacked solar cell solution.

[0003] The electrodes (anode and cathode) of traditional solar cells are located on the upper and lower sides of the substrate. Due to the influence of the front grid electrode, the power generation efficiency of the cell is not high and it is not beautiful. In addition, in traditional crystalline silicon solar cells, hydrogen atoms are injected into the doping layer to form Si-H bonds. Ultraviolet light irradiation will break the Si-H bonds, thereby reducing the performance of the cell.

[0004] Therefore, it is necessary to develop a laminated back-contact solar cell structure and a preparation method thereof to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to design a laminated back-contact solar cell structure and a preparation method thereof in order to solve the above-mentioned problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: Laminated back contact solar cell structure, including: Top cell; the top cell is a back-contact perovskite cell; the top cell is divided into three layers vertically connected to each other from the first side to the second side, the first layer is an isolation passivation layer, the second layer is a light absorption layer, and the third layer is a first structure layer and a second structure layer that are alternately distributed laterally, the first structure layer is divided into a second transmission layer, a transparent conductive layer, and a transparent insulating layer that are vertically connected to each other, wherein the second transmission layer is close to the first side of the top cell; the second structure layer is divided into a first transmission layer and a transparent conductive layer that are vertically connected to each other, wherein the first transmission layer is close to the first side of the top cell; the first structure layer and the second structure layer are laterally connected through a transparent insulating layer; Bottom cell; the bottom cell is a back-contact crystalline silicon cell; the bottom cell is divided into five layers vertically interconnected from the first side to the second side, the first layer is a passivation layer, the second layer is a silicon substrate, the third layer is a dielectric layer, the fourth layer is an alternately distributed first doping layer and a second doping layer, and the fifth layer is an alternately distributed metal electrode and a connection layer; the second side of the top cell is connected to the second side of the bottom cell; the second transmission layer corresponds to the vertical position of the second doping layer; the transparent conductive layer adjacent to the second transmission layer is connected to an external circuit, and the metal electrode adjacent to the second doping layer is connected to an external circuit to form a current loop.

[0007] The method for preparing a laminated back-contact solar cell structure comprises the following steps: S1. After the surface of the silicon substrate is textured and cleaned, a passivation layer is prepared on the back side by a PECVD method or a LPCVD method; S2, cleaning the upper surface of the silicon substrate again, and preparing a fully covered dielectric layer on the upper surface of the silicon substrate, the preparation method being PECVD method, thermal oxidation method, wet method, or LPCVD method; S3, using a mask method to prepare a first doping layer and a second doping layer on the dielectric layer, wherein the first doping layer and the second doping layer are prepared by a PECVD method or a LPCVD method; S4, annealing the first doping layer and the second doping layer; S5. Preparing metal electrodes on the first doping layer and the second doping layer by screen printing, electroplating, chemical plating, magnetron sputtering or evaporation coating. The width of the metal electrodes is 1-10 μm and the height is 20-200 μm. S6. Depositing a connection layer between two adjacent metal electrodes on the first doping layer and the second doping layer; the preparation method of the deposited connection layer is PECVD method or LPCVD method or magnetron sputtering or evaporation coating, and the connection layer is a single layer or a multilayer structure composed of materials with different refractive indices; S7. Using a mask method, a transparent insulating layer, a transparent conductive layer, and a second transmission layer of the first structure layer are sequentially prepared on the connecting layer, and a transparent conductive layer and a first transmission layer of the second structure layer are sequentially prepared, and the first structure layer and the second structure layer are laterally spaced apart; the second transmission layer is prepared from a metal oxide or an organic compound, and the first transmission layer is prepared from a Spiro-OMeTAD or polyethylene terephthalate or polytriarylamine or a metal oxide; S8, preparing a light absorbing layer on the first structural layer and the second structural layer, the chemical formula of the preparation material of the light absorbing layer is FA x Cs 1-x PbB y I 3-y , where x is 0.85 to 1, and y is 0 to 0.6; S9. Prepare an isolation passivation film on the light absorbing layer.

[0008] The beneficial effects of the present invention are: In the present application, the top cell is a back-contact perovskite cell, and the bottom cell is a back-contact crystalline silicon cell, and the back contact electrode of the perovskite cell is connected to the back contact electrode of the crystalline silicon cell. In this way, the positive and negative electrodes of the cell are located in the middle of the stacked cell. For double-sided solar cells, more light enters both sides of the cell, and no electrodes can be seen on both sides, which is more aesthetically pleasing.

[0009] In the present application, ultraviolet and short-wave light is mainly absorbed by the upper perovskite cell, while medium- and long-wave light is hardly absorbed by the doped layer. Therefore, the bottom cell has the electrode and doped layer side facing upward, and there is no need to consider the impact on light absorption.

[0010] In the present application, the ultraviolet light has been absorbed by the upper perovskite cell, so there is no need to consider the effect of ultraviolet light on the bottom cell doping layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 Schematic diagram of the structure of the top battery and the bottom battery in the present invention; Figure 3 It is a schematic diagram of the structure of the glass substrate in the present invention.

[0012] In the figure: 1: isolation passivation layer, 2: second transmission layer, 3: transparent conductive layer, 4: transparent insulating layer, 5: light absorption layer, 6: first transmission layer, 7: metal electrode, 8: second doping layer, 9: dielectric layer, 10: passivation layer, 11: connection layer, 12: first doping layer, 13: silicon substrate, 14: glass substrate. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0014] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0016] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0017] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0018] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] like Figure 1-2 As shown, the laminated back contact solar cell structure comprises: Top cell; the top cell is a back-contact perovskite cell; the top cell is divided into three layers vertically connected to each other from the first side to the second side, the first layer is an isolation passivation layer 1, the second layer is a light absorption layer 5, and the third layer is a first structure layer and a second structure layer that are alternately distributed laterally, the first structure layer is divided into a second transmission layer 2, a transparent conductive layer 3, and a transparent insulating layer 4 that are vertically connected to each other, wherein the second transmission layer 2 is close to the first side of the top cell; the second structure layer is divided into a first transmission layer 6 and a transparent conductive layer 3 that are vertically connected to each other, wherein the first transmission layer 6 is close to the first side of the top cell; the first structure layer and the second structure layer are laterally connected through a transparent insulating layer 4; Bottom cell; the bottom cell is a back-contact crystalline silicon cell; the bottom cell is divided into five layers vertically interconnected from the first side to the second side, the first layer is a passivation layer 10, the second layer is a silicon substrate 13, the third layer is a dielectric layer 9, the fourth layer is an alternately distributed first doping layer 12 and a second doping layer 8, and the fifth layer is an alternately distributed metal electrode 7 and a connecting layer 11; the second side of the top cell is connected to the second side of the bottom cell; the second transmission layer 2 corresponds to the vertical position of the second doping layer 8; the transparent conductive layer 3 adjacent to the second transmission layer 2 is connected to an external circuit, and the metal electrode 7 adjacent to the second doping layer 8 is connected to an external circuit to form a current loop.

[0021] In some embodiments, since the electrode is located in the middle of the stacked battery, in order to avoid the electrode blocking light, the electrode is a gate line electrode.

[0022] In some embodiments, the silicon substrate 13 is an n-type semiconductor doped with first type impurities; the first doped layer 12 is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with first type impurities; the second doped layer 8 is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with second type impurities.

[0023] In some embodiments, the thickness of the first doping layer 12 and the second doping layer 8 are both 10-500 nm.

[0024] In some embodiments, the dielectric layer 9 is made of silicon oxide, silicon carbide or silicon nitride.

[0025] In some embodiments, the thickness of dielectric layer 9 is 1-10 nm.

[0026] In some embodiments, the connection layer 11 is made of a transparent material, specifically a transparent insulating material or a transparent electrode material. The transparent electrode material may be ITO, IZO, ITiO, or the like.

[0027] In some embodiments, the passivation layer 10 is made of aluminum oxide, silicon nitride, or silicon carbide.

[0028] In some embodiments, the material of the isolation passivation layer 1 is any one of silicon oxide, PP, PE, PMMA, silica gel, and epoxy resin. The purpose of setting the isolation passivation layer 1 is to passivate the surface of the perovskite layer and isolate it from the air.

[0029] Embodiment 1: The method for preparing a laminated back-contact solar cell structure comprises the following steps: S1, the silicon substrate 13 is surface-textured and cleaned, and a passivation layer 10 is prepared on the back side by a PECVD method or a LPCVD method; S2, cleaning the upper surface of the silicon substrate 13 again, and preparing a fully covered dielectric layer 9 on the upper surface of the silicon substrate 13, the preparation method being PECVD method, thermal oxidation method, wet method or LPCVD method; S3, using a mask method, preparing a first doping layer 12 and a second doping layer 8 on the dielectric layer 9, wherein the first doping layer 12 and the second doping layer 8 are prepared by a PECVD method or a LPCVD method; S4, annealing the first doping layer 12 and the second doping layer 8; S5, preparing a metal electrode 7 on the first doping layer 12 and the second doping layer 8, the preparation method is screen printing or electroplating or chemical plating or magnetron sputtering or evaporation coating, the width of the metal electrode 7 is 1-10 μm, and the height is 20-200 μm; S6. Depositing a connection layer 11 between two adjacent metal electrodes 7 on the first doping layer 12 and the second doping layer 8; the preparation method of depositing the connection layer 11 is PECVD method or LPCVD method or magnetron sputtering or evaporation coating, and the connection layer 11 is a single layer or a multilayer structure of materials with different refractive indices; S7. Using a mask method, a transparent insulating layer 4, a transparent conductive layer 3, and a second transmission layer 2 of a first structure layer are sequentially prepared on the connecting layer 11, and a transparent conductive layer 3 and a first transmission layer 6 of a second structure layer are sequentially prepared, and the first structure layer and the second structure layer are laterally spaced apart; the second transmission layer 2 is prepared from a material of metal oxide (TiO2, ZnO, SnO2) or an organic compound (PCBM, C60), and the first transmission layer 6 is prepared from a material of Spiro-OMeTAD or polyethylene terephthalate (PEDOT:PSS) or poly(triarylamine) (PTAA) or a metal oxide (Cu2O, NiO, MoOx); in the present embodiment, the first transmission layer 6 is also a hole transmission layer, and the second transmission layer 2 is also an electron transmission layer.

[0030] S8, preparing a light absorbing layer 5 on the first structural layer and the second structural layer, the chemical formula of the preparation material of the light absorbing layer 5 is FA x Cs 1-x PbB y I 3-y , where x is 0.85 to 1, and y is 0 to 0.6; S9, preparing an isolation passivation film on the light absorbing layer 5.

[0031] Embodiment 2: The method for preparing the above-mentioned laminated back contact solar cell structure is to prepare the top cell on the upper surface of the bottom cell. Figure 3As shown, another method is to prepare a perovskite cell on a glass substrate 14 and then physically stack the two cells; the top cell is first prepared on the glass substrate 14, the material is consistent with that in Example 1, and the preparation order is reversed.

[0032] In the above two embodiments, the first transport layer 6 of the top battery is a hole transport layer, the second transport layer 2 is an electron transport layer, the first doping layer 12 of the bottom battery is doped with phosphorus, and the second doping layer 8 is doped with boron. The two batteries are connected in series, the transparent conductive layer 3 adjacent to the second transport layer 2 is connected to the external circuit, and the metal electrode 7 adjacent to the second doping layer 8 is connected to the external circuit to form a current loop.

[0033] Similarly, the materials of the first transmission layer 6 and the second transmission layer 2 can be interchanged. At this time, the doping elements of the first doping layer 12 and the second doping layer 8 are also interchanged. The two batteries can also be connected in series. The difference is that the positive and negative poles of the stacked battery are swapped.

[0034] 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 laminated back contact solar cell structure, characterized in that: include: Top battery; The top cell is a back-contact perovskite cell; The top battery is divided into three layers vertically connected to each other from the first side to the second side, the first layer is an isolation passivation layer, the second layer is a light absorption layer, and the third layer is a first structure layer and a second structure layer that are alternately distributed laterally. The first structure layer is divided into a second transmission layer, a transparent conductive layer, and a transparent insulating layer that are vertically connected to each other, wherein the second transmission layer is close to the first side of the top battery; the second structure layer is divided into a first transmission layer and a transparent conductive layer that are vertically connected to each other, wherein the first transmission layer is close to the first side of the top battery; the first structure layer and the second structure layer are laterally connected through a transparent insulating layer; Bottom cell; the bottom cell is a back-contact crystalline silicon cell; the bottom cell is divided into five layers vertically connected to each other from the first side to the second side, the first layer is a passivation layer, the second layer is a silicon substrate, the third layer is a dielectric layer, the fourth layer is an alternately distributed first doping layer and a second doping layer, and the fifth layer is an alternately distributed metal electrode and a connection layer; the second side of the top cell is connected to the second side of the bottom cell; The second transmission layer corresponds to the vertical position of the second doping layer; The transparent conductive layer adjacent to the second transmission layer is connected to an external circuit, and the metal electrode adjacent to the second doping layer is connected to the external circuit to form a current loop.

2. The laminated back contact solar cell structure according to claim 1, characterized in that: The silicon substrate is an n-type semiconductor doped with first-type impurities; the first doped layer is amorphous silicon, microcrystalline silicon or polycrystalline silicon doped with first-type impurities; the second doped layer is amorphous silicon, microcrystalline silicon or polycrystalline silicon doped with second-type impurities.

3. The laminated back contact solar cell structure according to claim 2, characterized in that: The thickness of the first doping layer and the second doping layer are both 10-500nm.

4. The laminated back contact solar cell structure according to claim 2, characterized in that: The first type of impurities is phosphorus and the second type of impurities is boron.

5. The laminated back contact solar cell structure according to claim 1, characterized in that: The dielectric layer is made of silicon oxide, silicon carbide or silicon nitride.

6. The laminated back contact solar cell structure according to claim 5, characterized in that: The thickness of the dielectric layer is 1-10 nm.

7. The laminated back contact solar cell structure according to claim 1, characterized in that: The connection layer is made of transparent material.

8. The laminated back contact solar cell structure according to claim 1, characterized in that: The passivation layer is made of aluminum oxide, silicon nitride or silicon carbide.

9. The laminated back contact solar cell structure according to claim 1, characterized in that: The preparation material of the isolation passivation layer is any one of silicon oxide, PP, PE, PMMA, silica gel and epoxy resin.

10. The method for preparing a laminated back-contact solar cell structure according to any one of claims 1 to 9, characterized in that: Includes steps: S1. After the surface of the silicon substrate is textured and cleaned, a passivation layer is prepared on the back side by a PECVD method or a LPCVD method; S2, cleaning the upper surface of the silicon substrate again, and preparing a fully covered dielectric layer on the upper surface of the silicon substrate, the preparation method being PECVD method, thermal oxidation method, wet method, or LPCVD method; S3, using a mask method to prepare a first doping layer and a second doping layer on the dielectric layer, wherein the first doping layer and the second doping layer are prepared by a PECVD method or a LPCVD method; S4, annealing the first doping layer and the second doping layer; S5. Preparing metal electrodes on the first doping layer and the second doping layer by screen printing, electroplating, chemical plating, magnetron sputtering or evaporation coating. The width of the metal electrodes is 1-10 μm and the height is 20-200 μm. S6, depositing a connection layer between two adjacent metal electrodes on the first doping layer and the second doping layer; The preparation method of the deposited connecting layer is PECVD method or LPCVD method or magnetron sputtering or evaporation coating, and the connecting layer is a single layer or a multilayer structure composed of materials with different refractive indices; S7, using a mask method, sequentially preparing a transparent insulating layer, a transparent conductive layer, and a second transmission layer of the first structure layer on the connecting layer, and sequentially preparing a transparent conductive layer and a first transmission layer of the second structure layer, wherein the first structure layer and the second structure layer are spaced apart in a lateral direction; The second transmission layer is made of metal oxide or organic compound, and the first transmission layer is made of Spiro-OMeTAD or polyethylene terephthalate or polytriarylamine or metal oxide; S8, preparing a light absorbing layer on the first structural layer and the second structural layer, the chemical formula of the preparation material of the light absorbing layer is FA x Cs 1- x PbB y I 3-y , where the size of x is 0.85 to 1, and the size of y is 0 to 0.6; S9. Prepare an isolation passivation film on the light absorbing layer.

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