Heterojunction solar cell and preparation method thereof

Abstract

The present invention relates to a heterojunction solar cell and a method for preparing the same. The method for preparing the heterojunction solar cell comprises the following steps: performing a texturing treatment on both sides of a silicon wafer, and then sequentially preparing an intrinsic layer, a doping layer, and a transparent conductive layer on the texturing surface; preparing a plurality of spaced silicon oxide units on a surface of the transparent conductive layer away from the doping layer, wherein the refractive index of the silicon oxide units is between the refractive index of air and the refractive index of the transparent conductive layer; preparing a grid electrode between adjacent silicon oxide units; and sequentially performing curing and light injection treatment to obtain a heterojunction solar cell. The method has low raw material cost, simple process, and is easy to implement. The heterojunction solar cell obtained by the method has high short-circuit current and photoelectric conversion efficiency.

Description

Technical Field

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

[0002] In order to allow more light to enter heterojunction (HJT) solar cells, thereby improving the short-circuit current and photoelectric conversion efficiency of heterojunction solar cells, there are two main traditional technical approaches. The first approach is to use a transparent conductive (TCO) layer as an anti-reflection layer. However, the material of the transparent conductive layer includes an indium oxide-based transparent conductive material. The metal indium (In) in the indium oxide-based transparent conductive material is a rare metal with a scarce content in the earth's crust. Therefore, the target material used for sputtering the indium oxide-based transparent conductive material is expensive, resulting in high raw material costs for heterojunction solar cells. The second approach is to sputter an MgF2 anti-reflection layer on the heterojunction solar cell. However, before sputtering the MgF2 anti-reflection layer, the main grid lines need to be blocked, and the sputtering of MgF2 will cause damage to the heterojunction solar cell, requiring subsequent photorepair or thermal repair, which is a complex process. Summary of the Invention

[0003] Based on this, it is necessary to provide a heterojunction solar cell and a preparation method thereof to address the above problems. The raw material cost of the preparation method is low, the process is simple, and it is easy to implement. The heterojunction solar cell obtained by the preparation method has excellent short-circuit current and photoelectric conversion efficiency.

[0004] The present invention provides a method for preparing a heterojunction solar cell, comprising the following steps:

[0005] Both sides of the silicon wafer are textured, and then an intrinsic layer, a doped layer and a transparent conductive layer are sequentially prepared on both textured surfaces;

[0006] A plurality of silicon oxide units are formed on a surface of the transparent conductive layer away from the doping layer, wherein the silicon oxide units have a refractive index between the refractive index of air and the refractive index of the transparent conductive layer;

[0007] preparing a gate line electrode between adjacent silicon oxide units; and

[0008] The curing and light injection processes are performed in sequence to obtain a heterojunction solar cell.

[0009] In one embodiment, the silicon oxide units are arranged in an array.

[0010] In one embodiment, in the step of preparing a gate line electrode between adjacent silicon oxide units, a distance between the gate line electrode and the adjacent silicon oxide units is 40 μm-60 μm.

[0011] In one embodiment, the refractive index of the transparent conductive layer is 1.8-2.1, and the refractive index of the silicon oxide unit is 1.35-1.55.

[0012] In one embodiment, the step of preparing a plurality of spaced-apart silicon oxide units on a surface of the transparent conductive layer away from the doping layer comprises:

[0013] providing silicon oxide slurry;

[0014] A plurality of silicon oxide slurry units are printed on a surface of the transparent conductive layer away from the doping layer and spaced apart from each other, and the silicon oxide units are obtained after drying.

[0015] In one embodiment, the silicon oxide slurry unit has a thickness of 1 μm-10 μm.

[0016] In one embodiment, the mass fraction of silicon oxide in the silicon oxide slurry is 40%-80%, and the particle size of silicon oxide is less than or equal to 10 μm.

[0017] In one embodiment, the drying temperature is 120°C-180°C.

[0018] A heterojunction solar cell is prepared by the above-mentioned heterojunction solar cell preparation method, comprising a silicon wafer and an intrinsic layer, a doped layer and a transparent conductive layer stacked in sequence on two velvet surfaces of the silicon wafer, wherein a surface of the transparent conductive layer away from the doped layer is further provided with a plurality of spaced silicon oxide units, and a grid line electrode is provided between adjacent silicon oxide units.

[0019] In one embodiment, the transparent conductive layer has a thickness of 45 nm to 60 nm, and the silicon oxide unit has a thickness of 1 μm to 10 μm.

[0020] In the method for preparing a heterojunction solar cell provided by the present invention, a plurality of spaced silicon oxide units are first prepared, and then a grid electrode is prepared between adjacent silicon oxide units, so that the patterns of the grid electrode and the silicon oxide units are opposite. When the silicon oxide units and the transparent conductive layer form a double-layer anti-reflection structure, on the one hand, the reflection of sunlight on the surface of the heterojunction solar cell can be reduced, allowing more photons to enter the heterojunction solar cell, thereby improving the short-circuit current and photoelectric conversion efficiency of the heterojunction solar cell without affecting other cell parameters of the heterojunction solar cell; on the other hand, the thickness of the transparent conductive layer can be reduced, thereby reducing the amount of raw materials used in the transparent conductive layer, and thus reducing the cost of the heterojunction solar cell.

[0021] In addition, the silicon oxide unit has good density and excellent water resistance and acid resistance. Therefore, the present invention can also improve the reliability of heterojunction solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of a method for preparing a heterojunction solar cell provided by the present invention;

[0023] Figure 2 A cross-sectional view of a heterojunction solar cell according to one embodiment of the present invention;

[0024] Figure 3 For the present invention Figure 2 A top view of a heterojunction solar cell is shown.

[0025] In the figure, 10, silicon wafer; 20, intrinsic layer; 30, doped layer; 40, transparent conductive layer; 50, silicon oxide unit; 60, gate line electrode. DETAILED DESCRIPTION

[0026] The heterojunction solar cell and its preparation method provided by the present invention will be further described below.

[0027] Combine Figures 1 to 3 As shown, the preparation method of the heterojunction solar cell provided by the present invention comprises the following steps:

[0028] S10, performing texturing on both sides of the silicon wafer 10, and then sequentially preparing an intrinsic layer 20, a doped layer 30 and a transparent conductive layer 40 on both texturing surfaces;

[0029] S20, forming a plurality of silicon oxide units 50 distributed at intervals on the surface of the transparent conductive layer 40 away from the doping layer 30;

[0030] S30, preparing a gate line electrode 60 between adjacent silicon oxide units 50; and

[0031] S40, performing curing and light injection treatments in sequence to obtain a heterojunction solar cell.

[0032] It should be noted that, since the intrinsic layer 20, the doping layer 30 and the transparent conductive layer 40 are sequentially prepared on both velvet surfaces in step S10, a bilaterally symmetrical structure is obtained in step S10. Specifically, step S10 includes the following steps:

[0033] S101, performing a texturing process on the silicon wafer 10 so that both sides of the silicon wafer 10 form a texturing structure;

[0034] S102, forming an intrinsic layer 20 and a doping layer 30 on both textured structures;

[0035] S103 , forming a transparent conductive layer 40 on a surface of the doping layer 30 away from the intrinsic layer 20 .

[0036] Step S101 includes: performing texturing treatment on the silicon wafer 10 using an alkaline solution, wherein the alkaline solution is selected from NaOH solution or KOH solution.

[0037] In one embodiment, the silicon wafer 10 is selected from an N-type silicon wafer 10 .

[0038] In step S102 , the intrinsic layer 20 and the doped layer 30 may be prepared by plasma enhanced chemical vapor deposition. Optionally, the intrinsic layer 20 is an intrinsic amorphous silicon layer, and the doped layer 30 is an N layer or a P layer formed of amorphous silicon or microcrystalline silicon.

[0039] In step S103 , the transparent conductive layer 40 may be prepared by physical vapor deposition. Optionally, the material of the transparent conductive layer 40 is an indium oxide-based transparent conductive material.

[0040] In step S20 , the refractive index of the silicon oxide unit 50 is between the refractive index of air and the refractive index of the transparent conductive layer 40 . In one embodiment, the refractive index of the transparent conductive layer 40 is 1.8-2.1, and the refractive index of the silicon oxide unit 50 is 1.35-1.55.

[0041] In one embodiment, the silicon oxide units 50 are arranged in an array.

[0042] The present invention does not limit the shape of the silicon oxide unit 50. For example, the silicon oxide unit 50 can be in the shape of a cube, a cuboid, a cylinder, or other geometric shapes.

[0043] In one embodiment, step S20 includes the following steps:

[0044] S201, providing silicon oxide slurry;

[0045] S202 , printing a plurality of spaced-apart silicon oxide slurry units on a surface of the transparent conductive layer 40 away from the doping layer 30 , and obtaining silicon oxide units 50 after drying.

[0046] In step S201 , the silicon oxide slurry includes silicon oxide, resin, solvent and additives.

[0047] Considering that the viscosity of the silicon oxide slurry affects the printing performance and the compactness of the silicon oxide unit 50 , in one embodiment, the mass fraction of silicon oxide in the silicon oxide slurry is 40%-80%.

[0048] In one embodiment, in order to better disperse silicon oxide in the silicon oxide slurry, the particle size of silicon oxide is less than or equal to 10 μm.

[0049] In step S202 , the step of printing a plurality of spaced silicon oxide slurry units includes placing a screen above the transparent conductive layer 40 away from the doping layer 30 , spreading silicon oxide slurry on the screen, and scraping the silicon oxide slurry into the meshes of the screen with a printing scraper.

[0050] In one embodiment, the printing pressure is 50N-70N; the printing speed is 100mm / s-300mm / s; the printing spacing is 1.2mm-1.6mm; and the scraper pressure is 1.7mm-2.1mm.

[0051] Considering the high temperature tolerance, in one embodiment, the drying temperature is 120° C.-180° C., so as to better remove the solvent in the silicon oxide slurry.

[0052] Compared with physical vapor deposition and chemical vapor deposition, the method of printing silicon oxide slurry units to form the silicon oxide unit 50 has the advantages of simple process and easy implementation.

[0053] Moreover, the silicon oxide unit 50 formed in step S20 has high density and thus has excellent water resistance and acid resistance, thereby improving the reliability of the heterojunction solar cell.

[0054] It should be noted that, in step S30 , the gate line electrode 60 is formed between adjacent silicon oxide units 50 , that is, the patterns of the silicon oxide units 50 and the gate line electrode 60 are opposite.

[0055] In one embodiment, when the gate line electrode 60 is formed between adjacent silicon oxide units 50 , the distance between the gate line electrode 60 and the adjacent silicon oxide units 50 is 40 μm-60 μm.

[0056] Therefore, in the preparation method of the heterojunction solar cell provided by the present invention, a plurality of spaced silicon oxide units 50 are first prepared, and then a gate electrode 60 is prepared between adjacent silicon oxide units 50, so that the pattern of the gate electrode 60 is opposite to that of the silicon oxide units 50. When the silicon oxide units 50 and the transparent conductive layer 40 form a double-layer anti-reflection structure, on the one hand, the reflection of sunlight on the surface of the heterojunction solar cell can be reduced, allowing more photons to enter the heterojunction solar cell, thereby improving the short-circuit current and photoelectric conversion efficiency of the heterojunction solar cell without affecting other cell parameters of the heterojunction solar cell; on the other hand, the thickness of the transparent conductive layer 40 can be reduced, thereby reducing the amount of raw materials used in the transparent conductive layer 40, and thus reducing the cost of the heterojunction solar cell.

[0057] Specifically, the raw material of the transparent conductive layer 40 can be reduced by more than 30%.

[0058] It should be noted that there is no limitation on the thickness difference between the gate electrode 60 and the silicon oxide unit 50 . The thickness of the gate electrode 60 may be greater than or equal to the thickness of the silicon oxide unit 50 , or may be less than the thickness of the silicon oxide unit 50 .

[0059] The present invention provides a heterojunction solar cell in one embodiment, which is prepared by the above-mentioned method for preparing a heterojunction solar cell, and includes a silicon wafer 10 and an intrinsic layer 20, a doping layer 30 and a transparent conductive layer 40 stacked in sequence on the velvet structure of the silicon wafer 10. The surface of the transparent conductive layer 40 away from the doping layer 30 is also provided with a plurality of spaced silicon oxide units 50, and a gate line electrode 60 is provided between adjacent silicon oxide units 50.

[0060] In one embodiment, the gate electrode 60 is composed of a first metal wire and a second metal wire. The first metal wire and the second metal wire are perpendicular to each other, and adjacent first metal wires and second metal wires surround each other to form a unit cell. The silicon oxide unit 50 is disposed in the unit cell.

[0061] In one embodiment, the thickness of the silicon oxide unit 50 is 1 μm-10 μm.

[0062] Because the silicon oxide units 50 are spaced apart and the gate electrode 60 is disposed between adjacent silicon oxide units 50 , i.e., the patterns of the gate electrode 60 and the silicon oxide units 50 are opposite, the silicon oxide units 50 and the transparent conductive layer 40 form a double-layer anti-reflection structure. This allows more light to be transmitted into the heterojunction solar cell, thereby improving the short-circuit current and photoelectric conversion efficiency of the heterojunction solar cell. Furthermore, the thickness of the transparent conductive layer 40 can be reduced, thereby reducing the amount of raw materials used in the transparent conductive layer 40 and lowering the cost of the heterojunction solar cell.

[0063] In a conventional heterojunction solar cell, the thickness of the transparent conductive layer 40 is 70 nm to 90 nm. In one embodiment, the thickness of the transparent conductive layer 40 in the heterojunction solar cell provided by the present invention can be reduced by more than 30%. The thickness of the transparent conductive layer 40 in the heterojunction solar cell of the present invention is 45 nm to 60 nm.

[0064] In one embodiment, the short-circuit current of the heterojunction solar cell of the present invention can be increased by 50 mA or more, and the photoelectric conversion efficiency can be increased by 0.1% or more.

[0065] Therefore, the heterojunction solar cell provided by the present invention has excellent short-circuit current and photoelectric conversion efficiency, and at the same time, is low in cost and highly competitive.

[0066] Hereinafter, the heterojunction solar cell and the preparation method thereof will be further described through the following specific embodiments.

[0067] Example 1

[0068] The two sides of the N-type silicon wafer 10 are textured using a NaOH solution, so that a textured structure is formed on both sides of the silicon wafer 10 .

[0069] The intrinsic layer 20 and the doping layer 30 are grown on the surface of the textured structure by using a plasma enhanced chemical vapor deposition method.

[0070] The transparent conductive layer 40 is deposited on the surface of the doping layer 30 away from the intrinsic layer 20 by using physical vapor deposition technology, wherein the material of the transparent conductive layer 40 is indium oxide-based transparent conductive material.

[0071] Referring to Table 1, silicon oxide slurry was provided. A screen was placed above the transparent conductive layer 40 and the silicon oxide slurry was spread evenly on the screen. A printing scraper scraped the silicon oxide slurry into the meshes of the screen to form a plurality of silicon oxide slurry units with a thickness of 6 μm, spaced apart and arranged in an array on the surface of the transparent conductive layer 40 away from the doped layer 30. The silicon oxide units 50 were formed by drying at 150° C. The printing pressure was 60 N, the printing speed was 200 mm / s, the printing pitch was 1.4 mm, and the scraper pressure was 1.9 mm.

[0072] A gate electrode 60 is formed between adjacent silicon oxide units 50 . The patterns of the silicon oxide units 50 and the gate electrode 60 are opposite. The distance between the gate electrode 60 and the adjacent silicon oxide units 50 is 50 μm.

[0073] The curing and light injection processes are performed in sequence to obtain a heterojunction solar cell.

[0074] Table 1

[0075] Silicon oxide resin dispersants additive solvent Example 1 62％ 13％ 5％ 5％ 15％

[0076] Comparative Example 1

[0077] The N-type silicon wafer 10 is textured using a NaOH solution, so that both sides of the silicon wafer 10 are provided with a textured structure.

[0078] The intrinsic layer 20 and the doping layer 30 are grown on the surface of the textured structure by using a plasma enhanced chemical vapor deposition method.

[0079] The transparent conductive layer 40 is deposited on the surface of the doping layer 30 away from the intrinsic layer 20 by using physical vapor deposition technology, wherein the material of the transparent conductive layer 40 is an indium oxide-based transparent conductive material.

[0080] A gate line electrode 60 is formed on a surface of the transparent conductive layer 40 away from the doping layer 30 .

[0081] The curing and light injection processes are performed in sequence to obtain a heterojunction solar cell.

[0082] The short-circuit current and photoelectric conversion efficiency of the heterojunction solar cells obtained in Example 1 and Comparative Example 1 were tested. Compared with the heterojunction solar cell obtained in Comparative Example 1, the short-circuit current of the heterojunction solar cell obtained in Example 1 was increased by 50 mA, and the photoelectric conversion efficiency was increased by 0.1%.

[0083] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a heterojunction solar cell, characterized in that: The following steps are involved: Both sides of the silicon wafer are textured, and then an intrinsic layer, a doped layer and a transparent conductive layer are sequentially prepared on both textured surfaces; A plurality of silicon oxide units are formed on a surface of the transparent conductive layer away from the doping layer, wherein the silicon oxide units have a refractive index between the refractive index of air and the refractive index of the transparent conductive layer; preparing a gate line electrode between adjacent silicon oxide units, wherein a distance between the gate line electrode and the adjacent silicon oxide units is 40 μm-60 μm; and Performing curing and light injection treatments in sequence to obtain a heterojunction solar cell; The step of preparing a plurality of spaced-apart silicon oxide units on a surface of the transparent conductive layer away from the doping layer comprises: Providing a silicon oxide slurry, wherein the particle size of the silicon oxide in the silicon oxide slurry is less than or equal to 10 μm; A plurality of silicon oxide slurry units are printed on a surface of the transparent conductive layer away from the doping layer and spaced apart from each other, and the silicon oxide units are obtained after drying.

2. The method for preparing a heterojunction solar cell according to claim 1, wherein: The silicon oxide units are arranged in an array.

3. The method for preparing a heterojunction solar cell according to claim 1, wherein: The refractive index of the transparent conductive layer is 1.8-2.1, and the refractive index of the silicon oxide unit is 1.35-1.

55.

4. The method for preparing a heterojunction solar cell according to any one of claims 1 to 3, characterized in that: The thickness of the silicon oxide slurry unit is 1 μm-10 μm.

5. The method for preparing a heterojunction solar cell according to any one of claims 1 to 3, characterized in that: The mass fraction of silicon oxide in the silicon oxide slurry is 40%-80%.

6. The method for preparing a heterojunction solar cell according to any one of claims 1 to 3, characterized in that: The temperature during the drying is 120°C-180°C.

7. A heterojunction solar cell, characterized in that: The heterojunction solar cell is prepared by the preparation method of a heterojunction solar cell according to any one of claims 1 to 6, and includes a silicon wafer and an intrinsic layer, a doped layer and a transparent conductive layer stacked in sequence on two velvet surfaces of the silicon wafer. The surface of the transparent conductive layer away from the doped layer is also provided with a plurality of spaced silicon oxide units, and a gate line electrode is provided between adjacent silicon oxide units.

8. The heterojunction solar cell according to claim 7, characterized in that: The thickness of the transparent conductive layer is 45 nm to 60 nm, and the thickness of the silicon oxide unit is 1 μm to 10 μm.

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