Laminated back contact solar cell structure

Abstract

The utility model discloses a laminated back contact solar cell structure which 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 utility model relates to the technical field of solar cells, in particular to a tandem back-contact solar cell structure. Background Art

[0002] At present, the theoretical limit efficiency of single-junction solar cells has been solved. In order to achieve higher photoelectric conversion efficiency, multi-junction solar cells are the development direction. Multi-junction solar cells are the superposition of multiple single-junction solar cells, also called tandem 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 respectively absorb and utilize solar cells in different bands, the tandem solar cell of perovskite + crystalline silicon battery is the most promising tandem solar cell solution.

[0003] The electrodes (anode and cathode) of traditional structure solar cells are respectively 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 battery is not high and it is not beautiful enough. And in traditional crystalline silicon solar cells, the doping layer will inject hydrogen atoms to form Si-H bonds. Ultraviolet light irradiation will break the Si-H bonds, thereby reducing the battery performance.

[0004] Therefore, it is necessary to develop a tandem back-contact solar cell structure to solve the above problems. Summary of the Utility Model

[0005] The purpose of the utility model is to design a tandem back-contact solar cell structure to solve the above problems.

[0006] The utility model realizes the above purpose through the following technical solutions:

[0007] The tandem back-contact solar cell structure includes:

[0008] A top cell; the top cell is a back-contact perovskite cell; the top cell is divided into three vertically connected layers in sequence 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 structural layer and a second structural layer that are alternately distributed horizontally. The first structural layer is sequentially divided into a second transmission layer, a transparent conductive layer, and a transparent insulating layer that are vertically connected, where the second transmission layer is close to the first side of the top cell; the second structural layer is sequentially divided into a first transmission layer and a transparent conductive layer that are vertically connected, where the first transmission layer is close to the first side of the top cell; the first structural layer and the second structural layer are horizontally connected through a transparent insulating layer;

[0009] Bottom cell; the bottom cell is a back-contact crystalline silicon cell; the bottom cell is divided into five vertically interconnected layers 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 second doping layer in the vertical position; the transparent conductive layer adjacent to the second transmission layer is connected to the external circuit, and the metal electrode adjacent to the second doping layer is connected to the external circuit to form a current loop.

[0010] The beneficial effects of the present utility model are as follows:

[0011] In this application, the top cell is a back-contact perovskite cell, 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 a bifacial solar cell, there is more incident light on both sides of the cell, and no electrodes can be seen on both sides, which is more aesthetically pleasing.

[0012] In this application, ultraviolet and short-wavelength light are mainly absorbed by the upper perovskite cell, and medium-long and long-wavelength light is hardly absorbed by the doping layer. Therefore, the bottom cell has the side with the electrode and the doping layer facing upward, without considering the influence on light absorption.

[0013] In this application, the ultraviolet part of the light has been absorbed by the upper perovskite cell, so there is no need to consider the influence of ultraviolet light on the doping layer of the bottom cell either. Description of the Drawings

[0014] Figure 1 is a schematic structural diagram of the present utility model;

[0015] Figure 2 is a schematic structural diagram of the top cell and the bottom cell in the present utility model;

[0016] Figure 3 is a schematic structural diagram of the glass substrate in the present utility model.

[0017] 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 Embodiments

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of them. The components of the embodiments of the present utility model usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present utility model provided in the accompanying drawings is not intended to limit the scope of the claimed present utility model, but merely represents selected embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0021] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships when the product of this utility model is usually placed, or the orientation or positional relationships commonly understood by those skilled in the art. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0022] In addition, the terms "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present utility model, it should also be noted that unless otherwise clearly defined and limited, terms such as "set", "connect" should be understood in a broad sense. For example, "connect" 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, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0024] The following will specifically describe the embodiments of the present utility model in conjunction with the accompanying drawings.

[0025] As Figure 1-2 shown, the laminated back-contact solar cell structure includes:

[0026] Top cell; the top cell is a back-contact perovskite cell; the top cell is sequentially divided into three vertically interconnected layers from the first side to the second side. The first layer is an isolation passivation layer 1, the second layer is a light-absorbing layer 5, and the third layer is a first structural layer and a second structural layer that are alternately distributed horizontally. The first structural layer is sequentially divided into a second transport layer 2, a transparent conductive layer 3, and a transparent insulating layer 4 that are vertically interconnected, where the second transport layer 2 is close to the first side of the top cell; the second structural layer is sequentially divided into a first transport layer 6 and a transparent conductive layer 3 that are vertically interconnected, where the first transport layer 6 is close to the first side of the top cell; the first structural layer and the second structural layer are horizontally connected by a transparent insulating layer 4;

[0027] Bottom cell; the bottom cell is a back-contact crystalline silicon cell; the bottom cell is sequentially divided into five vertically interconnected layers 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 second doping layer 8, and the fifth layer is an alternately distributed metal electrode 7 and connection layer 11; the second side of the top cell is connected to the second side of the bottom cell; the vertical positions of the second transport layer 2 and the second doping layer 8 correspond; the transparent conductive layer 3 adjacent to the second transport 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.

[0028] In some embodiments, since the electrodes are located in the middle of the stacked cell, in order to avoid light blocking by the electrodes, the electrodes are grid electrodes.

[0029] In some embodiments, the silicon substrate 13 is an n-type semiconductor doped with a first type of impurity; the first doping layer 12 is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with a first type of impurity; the second doping layer 8 is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with a second type of impurity.

[0030] In some embodiments, the thicknesses of both the first doping layer 12 and the second doping layer 8 are 10 - 500 nm.

[0031] In some embodiments, the preparation material of the dielectric layer 9 is silicon oxide or silicon carbide or silicon nitride.

[0032] In some embodiments, the thickness of the dielectric layer 9 is 1 - 10 nm.

[0033] In some embodiments, the preparation material of the connection layer 11 is a transparent material. Specifically, it is a transparent insulating material or a transparent electrode material, and the transparent electrode material can be selected as ITO or IZO or ITiO, etc.

[0034] In some embodiments, the preparation material of the passivation layer 10 is aluminum oxide or silicon nitride or silicon carbide.

[0035] In some embodiments, the material for preparing 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.

[0036] Example 1:

[0037] A method for preparing a stacked back-contact solar cell structure includes the steps:

[0038] S1. The silicon substrate 13 is subjected to surface texturing and cleaning, and a passivation layer 10 is prepared on the back surface. The preparation method is PECVD method or LPCVD method;

[0039] S2. The upper surface of the silicon substrate 13 is cleaned again, and a full-coverage dielectric layer 9 is prepared on the upper surface of the silicon substrate 13. The preparation method is PECVD method or thermal oxidation method or humidification method or LPCVD method;

[0040] S3. By using a masking method, a first doping layer 12 and a second doping layer 8 are prepared on the dielectric layer 9. The preparation methods of the first doping layer 12 and the second doping layer 8 are PECVD method or LPCVD method;

[0041] S4. Anneal the first doping layer 12 and the second doping layer 8;

[0042] S5. A metal electrode 7 is prepared on the first doping layer 12 and the second doping layer 8. The preparation method is screen printing or electroplating or electroless 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;

[0043] S6. On the first doping layer 12 and the second doping layer 8, a connection layer 11 is deposited between two adjacent metal electrodes 7; the preparation method of depositing the connection layer 11 is PECVD method or LPCVD method or magnetron sputtering or evaporation coating. The connection layer 11 is a single layer or a multi-layer structure stacked by materials with different refractive indexes;

[0044] S7. By using a masking method, a transparent insulating layer 4, a transparent conductive layer 3, and a second transport layer 2 of the first structure layer are sequentially prepared on the connection layer 11, and a transparent conductive layer 3 and a first transport layer 6 of the second structure layer are sequentially prepared. The first structure layer and the second structure layer are horizontally spaced apart; the material for preparing the second transport layer 2 is metal oxide (TiO2, ZnO, SnO2) or organic compound (PCBM, C60), and the material for preparing the first transport layer 6 is Spiro-OMeTAD or polyethylene terephthalate (PEDOT:PSS) or poly(triarylamine) (PTAA) or metal oxide (Cu2O, NiO, MoOx); in this embodiment, the first transport layer 6 is also a hole transport layer, and the second transport layer 2 is also an electron transport layer.

[0045] S8. Prepare an absorbing layer 5 on the first structural layer and the second structural layer. The chemical formula of the material for preparing the absorbing layer 5 is FA x Cs 1-x PbBr y I 3-y , where the value of x ranges from 0.85 to 1, and the value of y ranges from 0 to 0.6;

[0046] S9. Prepare an isolation and passivation film on the absorbing layer 5.

[0047] Example 2:

[0048] The preparation method of the above-mentioned stacked back-contact solar cell structure is to prepare a top cell on the upper surface of the bottom cell. As Figure 3 shown, there is another way 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, and the materials are the same as those in Example 1, but the preparation sequence is reversed.

[0049] In the above two examples, the first transport layer 6 of the top cell is a hole transport layer, the second transport layer 2 is an electron transport layer, the first doping layer 12 of the bottom cell is doped with phosphorus, and the second doping layer 8 is doped with boron. The two cells are connected in series in an electrical circuit. The transparent conductive layer 3 adjacent to the second transport 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.

[0050] Similarly, the materials of the first transport layer 6 and the second transport 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, and the two cells can also be connected in series. The difference is that the positive and negative poles of the stacked cell are in reverse positions.

[0051] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Laminated back-contact solar cell structure, characterized in that, Comprising: Top cell; The top cell is a back-contact perovskite cell; The top cell is successively divided into three vertically interconnected layers from the first side to the second side. The first layer is an isolation passivation layer, the second layer is a light-absorbing layer, and the third layer is a first structural layer and a second structural layer that are alternately distributed horizontally. The first structural layer is successively divided into a second transport layer, a transparent conductive layer, and a transparent insulating layer that are vertically interconnected, where the second transport layer is close to the first side of the top cell; the second structural layer is successively divided into a first transport layer and a transparent conductive layer that are vertically interconnected, where the first transport layer is close to the first side of the top cell; the first structural layer and the second structural layer are connected horizontally through a transparent insulating layer; Bottom cell; The bottom cell is a back-contact crystalline silicon cell; The bottom cell is successively divided into five vertically interconnected layers 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 vertical positions of the second transport layer and the second doping layer correspond; The transparent conductive layer adjacent to the second transport 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.

2. The stacked back-contact solar cell structure according to claim 1, wherein, The silicon substrate is an n-type semiconductor doped with a first type of impurity; The first doping layer is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with a first type of impurity; The second doping layer is amorphous silicon or microcrystalline silicon or polycrystalline silicon doped with a second type of impurity.

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

4. The stacked back-contact solar cell structure according to claim 2, wherein, The first type of impurity is phosphorus, and the second type of impurity is boron.

5. The stacked back-contact solar cell structure according to claim 1, wherein The preparation material of the dielectric layer is silicon oxide or silicon carbide or silicon nitride.

6. The stacked back-contact solar cell structure according to claim 5, wherein, The thickness of the dielectric layer is 1 - 10 nm.

7. The stacked back-contact solar cell structure according to claim 1, characterized in that, The preparation material of the connection layer is a transparent material.

8. The stacked back-contact solar cell structure according to claim 1, wherein The preparation material of the passivation layer is aluminum oxide or silicon nitride or silicon carbide.

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

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