Heterojunction solar cell

Abstract

The utility model discloses a heterojunction solar cell. The heterojunction solar cell sequentially comprises a front electrode, a TCO film layer, a P-type nanometer doped layer, an intrinsic amorphous silicon layer, a silicon substrate, an intrinsic amorphous silicon layer, an N-type nanometer doped layer, a TCO film layer and a back electrode from top to bottom, and the front electrode and the back electrode adopt graphene electrodes which are in contact with the TCO film layer to realize a conductive function. The graphene electrode is used for replacing a silver electrode, the current transmission performance is not inferior to that of the silver electrode, but the production cost is greatly reduced; the graphene electrode is good in light transmission, high in electric conductivity, good in heat conductivity and excellent in optical performance, and the absorption efficiency and the conversion efficiency of the cell on sunlight are improved; the graphene electrode layer is prepared through deposition, the process is mature and simple, equipment is small, and the production cost is low.

Description

Technical Field

[0001] The utility model relates to a photovoltaic cell, in particular to a heterojunction solar cell. Background Art

[0002] The heterojunction cell is a cell based on the photovoltaic effect. Its unique double-sided stacked structure and excellent passivation effect of the amorphous silicon layer enable it to have high conversion efficiency, high double-sided efficiency, extremely low light attenuation rate, good temperature characteristics, and a short preparation process flow. However, it uses a large amount of silver paste, has a large wet weight, and a high production cost. With the rapid expansion of the photovoltaic industry, the explosive growth of production capacity, and fierce competition among enterprises, the prices of photovoltaic products have continued to decline. Coupled with external conflicts, the price of silver has continued to rise, casting a shadow over the cost reduction path of photovoltaic enterprises. As a metal with excellent conductivity, silver plays a crucial role in the field of photovoltaic cell manufacturing. It is mainly made into silver paste and then printed onto the cell surface through screen printing to form electrodes. According to statistical data, the cost of silver paste for a single cell accounts for approximately 40% - 60% of the total non-silicon cost. If the price of silver further increases, this proportion will further rise. At present, the price of silver has reached a maximum of 8,000 yuan / kg, with a nearly 100% increase compared to 4,000 yuan / kg in 2022. This problem has seriously restricted the further cost reduction and development of the photovoltaic industry. In response to the above problems, researchers in the industry have begun to try to incorporate copper components into the silver paste to reduce the silver content, and the copper content can reach up to 40%. However, there are still many difficulties: on the one hand, the introduction of copper materials will reduce the current transmission efficiency and cause the overall cell efficiency to decrease by about 0.1%; on the other hand, at the component end, copper is more easily oxidized, resulting in low stability and reliability. In addition, the non-transparency of silver will cause partial shading of the photovoltaic panel, reducing the light absorption efficiency and conversion efficiency of the cell. Summary of the Utility Model

[0003] Purpose of the Utility Model: The purpose of the utility model is to provide a heterojunction solar cell to reduce the production cost of the heterojunction cell and improve the light absorption efficiency and conversion efficiency of the cell for sunlight.

[0004] Technical Solution: The heterojunction solar cell described in the utility model includes a front electrode, a TCO film layer, a P-type nano-doped layer, an intrinsic amorphous silicon layer, a silicon substrate, an intrinsic amorphous silicon layer, an N-type nano-doped layer, a TCO film layer, and a back electrode from top to bottom in sequence; the front electrode and the back electrode adopt graphene electrodes that are in contact with the TCO film layer to achieve the conductive function.

[0005] Further, the deposition thickness of the graphene electrode is 1 - 10 nm, and the width is 20 - 30 nm. The resistivity of the graphene electrode with a certain thickness and width remains at 70 - 100 Ω / cm 2The overall area of ​​the electrode accounts for 0.2% to 0.4% of the entire cell area. Graphene has excellent conductivity and its current transmission performance is no less than that of silver electrodes. Therefore, the layout of graphene electrodes does not need to be increased. The area of ​​the electrode can be reduced as much as possible while meeting the current transmission performance. Replacing silver electrodes greatly reduces production costs.

[0006] Furthermore, after the graphene electrode is prepared, its transmittance is maintained at 80-97%, with good light transmittance, good thermal conductivity and excellent optical properties, and no shielding of sunlight, thereby improving the battery's absorption efficiency and conversion efficiency of sunlight.

[0007] Furthermore, a mask layer is provided between the graphene electrode layer and the TCO film layer to protect the TCO film layer when the electrode layer is prepared by the deposition method. A leak hole is provided on the mask layer for depositing the graphene electrode. The shape and size of the leak hole are set according to the specifications and size of the electrode. The mask layer is resistant to high temperatures of 200 to 300°C. The mask layers on the front and back of the battery are set the same. After the electrode is deposited, it is located in the middle of the battery. The electrode contour range shall not be less than 99% of the battery contour size. The deposition method is used to prepare the graphene electrode layer. The process is relatively mature and streamlined, and the equipment is small, which further reduces the production cost of the battery cell.

[0008] Beneficial effects: Compared with the prior art, the utility model has the following advantages: 1. The graphene electrode replaces the silver electrode, and the current transmission performance is no less than that of the silver electrode, but the production cost is greatly reduced; 2. The graphene electrode has good light transmittance, high conductivity, good thermal conductivity and excellent optical properties, which improves the battery's absorption efficiency and conversion efficiency of sunlight; 3. The graphene electrode layer is prepared by deposition, with a mature and streamlined process, small equipment and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0010] The technical solution of the utility model is further described below in conjunction with the accompanying drawings.

[0011] like Figure 1 A heterojunction solar cell shown in the figure includes, from top to bottom, a front graphene electrode 6, a mask layer 7, a TCO film layer 1, a P-type nano-doped layer 2, an intrinsic amorphous silicon layer 3, a silicon substrate 5, an intrinsic amorphous silicon layer 3, an N-type nano-doped layer 4, a TCO film layer 1, a mask layer 7, and a back graphene electrode 6. The deposition thickness of the graphene electrode 6 is 1 to 10 nm, the width is 20 to 30 nm, the transmittance is 80 to 97%, and the resistivity is 70 to 100 Ω / cm 2。The mask layer 7 can withstand high temperatures of 200 - 300 °C, and leakage holes 8 for depositing the graphene electrodes 6 are provided thereon. The shape and size of the leakage holes 8 are set according to the specifications and dimensions of the electrodes (for example: when the battery size is 182 mm * 182 mm, the graphene electrodes can be set to 182 mm * 3 - 15 nm, 40 - 70 pieces; when the battery size is 210 mm * 210 mm, the graphene electrodes can be set to 210 mm * 3 - 15 nm, 60 - 90 pieces).

[0012] The manufacturing method of the above heterojunction solar cell includes the following steps:

[0013] Step 1, clean the N-type silicon substrate and perform double-sided texturing on it to obtain a double-textured N-type silicon substrate 5;

[0014] Step 2, deposit an intrinsic amorphous silicon layer 3 with a certain thickness on the two textured surfaces of the double-textured N-type silicon substrate 5 by chemical vapor deposition;

[0015] Step 3, deposit a P-type nano-doped layer 2 and an N-type nano-doped layer 4 with a certain thickness on the two intrinsic amorphous silicon layers 3 respectively by chemical vapor deposition;

[0016] Step 4, deposit a TCO film layer 1 with a certain thickness on the P-type nano-doped layer 2 and the N-type nano-doped layer 4 by physical vapor deposition;

[0017] Step 5, lay a mask layer 7 on the TCO film layer 1. The size ratio of the mask layer 7 is greater than or equal to the size of the battery cell. Leakage holes 8 for the next electrode deposition are provided on the mask layer 7;

[0018] Step 6, deposit graphene electrodes with a thickness of 1 - 10 nm and a width of 20 - 30 nm in the leakage holes 8 of the mask layer 7 by chemical vapor deposition, as the front and back electrodes of the battery;

[0019] Step 7, remove the mask layer 7.

Claims

1. A heterojunction solar cell, which sequentially includes a front electrode, a TCO film layer (1), a P-type nano-doped layer (2), an intrinsic amorphous silicon layer (3), a silicon substrate (5), an intrinsic amorphous silicon layer (3), an N-type nano-doped layer (4), a TCO film layer (1), and a back electrode from top to bottom; and is characterized in that, The front electrode and the back electrode adopt a graphene electrode (6) that contacts the TCO film layer (1) to achieve the conductive function.

2. The heterojunction solar cell according to claim 1, wherein, The deposition thickness of the graphene electrode (6) is 1 to 10 nm.

3. The heterojunction solar cell according to claim 1, wherein, The width of the graphene electrode (6) is 20 to 30 nm.

4. The heterojunction solar cell according to claim 1, wherein, The area of the graphene electrode (6) accounts for 0.2% to 0.4% of the area of the entire cell.

5. The heterojunction solar cell according to claim 1, characterized in that, The resistivity of the described graphene electrode (6) is 70 to 100 Ω / cm 2 .

6. The heterojunction solar cell according to claim 1, wherein The light transmittance of the graphene electrode (6) is 80 to 97%.

7. The heterojunction solar cell according to claim 1, wherein A mask layer (7) for protecting the TCO film layer during the deposition of the electrode layer is provided between the graphene electrode layer and the TCO film layer, and a leakage hole (8) for depositing the graphene electrode (6) is provided on the mask layer (7).

8. The heterojunction solar cell according to claim 7, wherein The shape and size of the leakage hole (8) are set according to the specifications and dimensions of the electrode.

9. The heterojunction solar cell according to claim 7, wherein The mask layer (7) is resistant to high temperatures of 200 to 300 °C.

Images