Heterojunction solar cell and preparation method thereof

Abstract

The invention relates to a heterojunction solar cell and a preparation method thereof. The heterojunction solar cell comprises a silicon wafer; a first intrinsic amorphous silicon layer, an N-type doped layer, a first TCO layer and a first grid electrode are sequentially arranged on the front face of the silicon wafer in a stacked mode. A second intrinsic amorphous silicon layer, a P-type doped layer, a second TCO layer and a second grid electrode are sequentially stacked on the back surface of the silicon wafer; wherein the first grid electrode is hydrophilic, the first TCO layer comprises a first area and a second area, the first grid electrode is arranged in the first area, the second area is hydrophobic, the contact angle is larger than 150 degrees, and the rolling angle is smaller than 1 degree; and / or, the second grid electrode is hydrophilic, the second TCO layer comprises a third area and a fourth area, the second grid electrode is arranged in the third area, the fourth area is hydrophobic, the contact angle is larger than 150 degrees, and the rolling angle is smaller than 1 degree. The heterojunction solar cell has the advantages of being good in waterproofness, high in reliability and self-cleaning, meanwhile, the preparation method is simple, photoresist does not need to be adopted, and the heterojunction solar cell is environmentally friendly and low in cost.

Description

Technical Field

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

[0002] The core processes of heterojunction solar cells are patterning and metal electroplating, such as copper electroplating. In the patterning process of heterojunction solar cells, photoresist is usually used to achieve the patterning of heterojunction solar cells. However, photoresist has the following obvious defects: (1) The production and use of photoresist may release volatile organic compounds (VOCs), which may have adverse effects on the environment and the health of operators; (2) The cost of photoresist is relatively high, and its application process requires specific equipment and process conditions for coating, exposure and development, which undoubtedly increases the cost investment of the entire production process; (3) In the subsequent removal process of photoresist, strong chemical reagents are often required. If these chemical reagents are not handled and discharged properly, they may cause serious pollution to the environment; (4) In some cases, the resolution and accuracy of photoresist may not meet the increasingly high requirements of heterojunction solar cell patterning process, which may limit the further improvement of battery performance and process optimization. Summary of the invention

[0003] Based on this, it is necessary to provide a heterojunction solar cell and a method for preparing the same to address the above problems. The heterojunction solar cell has the characteristics of good waterproofness, strong reliability and self-cleaning. At the same time, the preparation method is simple, does not require the use of photoresist, is green and environmentally friendly, and has low cost.

[0004] A heterojunction solar cell, comprising:

[0005] A silicon wafer having a front side and a back side arranged opposite to each other;

[0006] A first intrinsic amorphous silicon layer, an N-type doped layer, a first TCO layer and a first gate are sequentially stacked on the front side of the silicon wafer;

[0007] A second intrinsic amorphous silicon layer, a P-type doping layer, a second TCO layer and a second gate are sequentially stacked on the back side of the silicon wafer;

[0008] The first gate is hydrophilic, the first TCO layer includes a first region and a second region, the first gate is arranged in the first region, the second region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°; and / or the second gate is hydrophilic, the second TCO layer includes a third region and a fourth region, the second gate is arranged in the third region, the fourth region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°.

[0009] In one embodiment, the roughness of the surface of the first TCO layer at the second region is selected from 50 nm to 150 nm, and the second region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound;

[0010] And / or, the surface roughness of the second TCO layer at the fourth region is selected from 50 nm to 150 nm, and the fourth region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound.

[0011] In one embodiment, the surface energy of the second region is selected from 10 J / m 2 -30J / m 2 ;

[0012] And / or, the surface energy of the fourth region is selected from 10 J / m 2 -30J / m 2 .

[0013] In one embodiment, the surface of the first TCO layer at the second region and / or the surface of the second TCO layer at the fourth region has a hydrophobic layer.

[0014] In one embodiment, the hydrophobic layer is a monomolecular self-assembled layer, the material of the monomolecular self-assembled layer is an organic material SAM, and the molecular structure of the organic material SAM is composed of three characteristic units I, II, and III connected in sequence, wherein the I unit is selected from a Lewis acid or a Lewis acid derivative, the II unit is selected from a pyridine-based organic ligand, and the III unit is selected from an organic hydrophobic group.

[0015] In one embodiment, the thickness of the hydrophobic layer is 5nm-200nm.

[0016] The heterojunction solar cell of the present invention has super-hydrophobic properties in the second region and / or the fourth region, which can effectively improve the waterproof performance of the heterojunction solar cell and improve the stability and reliability of the heterojunction solar cell structure; and, since the rolling angle of the second region and / or the fourth region is less than 1°, the droplets can easily roll off the surface thereof, taking away pollutants such as dust on the surface, achieving a self-cleaning effect, thereby making the heterojunction solar cell have a self-cleaning effect. Therefore, the heterojunction solar cell of the present invention has the characteristics of good waterproofness, strong reliability and self-cleaning.

[0017] A method for preparing the heterojunction solar cell as described above comprises the following steps:

[0018] The silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side;

[0019] A first metal seed layer is prepared on the surface of the first region of the first TCO layer, and a second region of the first TCO layer is subjected to a hydrophobic treatment to make the second region hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°; then a first metal electrode is prepared on the surface of the first metal seed layer by electroplating, and a second metal electrode is prepared on the third region of the second TCO layer by printing to obtain a heterojunction solar cell;

[0020] Alternatively, the silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side;

[0021] A second metal seed layer is prepared on the surface of the third region of the second TCO layer, and a fourth region of the second TCO layer is subjected to a hydrophobic treatment to make the fourth region hydrophobic, wherein a contact angle is greater than 150° and a rolling angle is less than 1°; then a first metal electrode is prepared on the second region of the first TCO layer by a printing method, and a second metal electrode is prepared on the surface of the second metal seed layer by an electroplating method to obtain a heterojunction solar cell;

[0022] Alternatively, the silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side;

[0023] A first metal seed layer is prepared on the surface of the first area of ​​the first TCO layer, and a second metal seed layer is prepared on the surface of the third area of ​​the second TCO layer. The second area of ​​the first TCO layer and the fourth area of ​​the second TCO layer are hydrophobicized to make the second area and the fourth area hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°. Then, a first metal electrode is prepared on the surface of the first metal seed layer by electroplating, and a second metal electrode is prepared on the surface of the second metal seed layer to obtain a heterojunction solar cell.

[0024] In one embodiment, the hydrophobic treatment method is selected from chemical vapor deposition, self-assembled monolayer, nano-coating, laser etching or plasma etching.

[0025] In one embodiment, when the hydrophobic treatment method is selected from plasma etching, the working gas includes a first gas and a second gas, the first gas is selected from at least one of nitrogen, oxygen or argon, and the second gas is selected from fluorine-containing gas, organosilicon gas or hydrocarbon organic gas.

[0026] In one embodiment, when the hydrophobic treatment method is selected from the self-assembled monolayer method, the self-assembled monolayer material used is selected from the organic material SAM, and the molecular structure of the organic material SAM is composed of three characteristic units I, II, and III connected in sequence, wherein the I unit is selected from a Lewis acid or a Lewis acid derivative, the II unit is selected from a pyridine organic ligand, and the III unit is selected from an organic hydrophobic group.

[0027] In the preparation method of the heterojunction solar cell of the present invention, the first metal seed layer and / or the second metal seed layer have good hydrophilicity, and the second region and / or the fourth region are hydrophobically treated to form a super-hydrophobic region, so that the surface of the first TCO layer and the surface of the second TCO layer form a hydrophilic-hydrophobic composite pattern, and the effect of patterning without photoresist is achieved. This method can effectively avoid the problems caused by the use of photoresist, greatly reduce the pressure of environmental pollution, shorten the process flow of patterning, reduce costs, and also improve the waterproof performance of the solar cell and the reliability of the solar cell; and, since the second region and / or the fourth region are super-hydrophobic regions, when the first metal electrode and / or the second metal electrode are prepared by electroplating, the electroplating solution will basically not contact the second region and / or the fourth region, so that the second region and / or the fourth region will basically not have the phenomenon of depositing metal electrodes. Therefore, the preparation method of the heterojunction solar cell of the present invention is simple to operate, does not need to use photoresist, is green and environmentally friendly, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the structure of the heterojunction solar cell of the present invention, wherein, in the figure, A represents the second region and B represents the fourth region.

[0030] Figure numerals: 1, silicon wafer; 2, first intrinsic amorphous silicon layer; 3, second intrinsic amorphous silicon layer; 4, N-type doped layer; 5, P-type doped layer; 6, first TCO layer; 7, second TCO layer; 8, first metal seed layer; 9, second metal seed layer; 10, first metal electrode; 11, second metal electrode. DETAILED DESCRIPTION

[0031] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation or embodiment, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0033] like Figure 1 As shown, the heterojunction solar cell provided by the present invention comprises: a silicon wafer 1, wherein the silicon wafer 1 has a front side and a back side arranged opposite to each other; a first intrinsic amorphous silicon layer 2, an N-type doped layer 4, a first TCO layer 6 and a first gate are sequentially stacked on the front side of the silicon wafer 1, and a second intrinsic amorphous silicon layer 3, a P-type doped layer 5, a second TCO layer 7 and a second gate are sequentially stacked on the back side of the silicon wafer 1.

[0034] The first gate is hydrophilic, the first TCO layer 6 includes a first region and a second region, the first gate is arranged in the first region, the second region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°; and / or the second gate is hydrophilic, the second TCO layer 8 includes a third region and a fourth region, the second gate is arranged in the third region, the fourth region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°.

[0035] In the present invention, the second region of the first TCO layer 6 and / or the fourth region of the second TCO layer 8 are hydrophobic, and the contact angle and the rolling angle of the second region and / or the fourth region are limited, so that the first non-gridline region and the second non-gridline region have super-hydrophobic properties, which can effectively improve the waterproof performance of the heterojunction solar cell and improve the stability and reliability of the heterojunction solar cell structure; and, since the rolling angle of the second region and / or the fourth region is less than 1°, the droplets can easily roll off its surface, taking away dust and other pollutants on its surface, achieving a self-cleaning effect, so that the heterojunction solar cell has a self-cleaning effect. Therefore, the heterojunction solar cell of the present invention has the characteristics of good waterproofness, strong reliability and self-cleaning.

[0036] It should be noted that in the present invention, according to the definition, when the contact angle between water and the material is less than 90°, the material behaves as hydrophilic, when it is less than 10°, the material behaves as superhydrophilic, and when it is greater than 90°, the material behaves as hydrophobic, and when it is greater than 150°, the material behaves as superhydrophobic.

[0037] It can be understood that, in the present invention, the first region is the first gate region, and the second region is the region where the first TCO layer 6 is away from the surface of the N-type doped layer 4 and is not provided with the first gate, that is, the first non-gate region. Similarly, the third region is the second gate region, and the fourth region is the region where the second TCO layer 8 is away from the surface of the P-type doped layer 5 and is not provided with the second gate, that is, the second non-gate region.

[0038] Optionally, the surface roughness of the first TCO layer 6 at the second region is selected from 50nm-150nm, and the second region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound. In this way, the roughness of the surface of the first TCO layer 6 can be controlled, and the compound components in the second region can be coordinated to adjust the hydrophobicity of the second region, so that the second region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°.

[0039] Optionally, the surface roughness of the second TCO layer 7 at the fourth region is selected from 50nm-150nm, and the fourth region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound. In this way, the hydrophobicity of the fourth region can be regulated by controlling the surface roughness of the second TCO layer 7 and coordinating with the compound components contained in the fourth region, so that the fourth region is hydrophobic, and the contact angle is greater than 150° and the rolling angle is less than 1°.

[0040] Optionally, the surface energy of the second region is selected from 10 J / m 2 -30J / m 2Such an arrangement is conducive to making the second region have better super-hydrophobic properties.

[0041] Optionally, the surface energy of the fourth region is selected from 10 J / m 2 -30J / m 2 Such an arrangement is conducive to making the fourth region have better super-hydrophobic properties.

[0042] Optionally, the surface of the first TCO layer 6 at the second region and / or the surface of the second TCO layer 7 at the fourth region has a hydrophobic layer. In this way, by providing the hydrophobic layer, the second region and / or the fourth region is hydrophobic, and the contact angle is greater than 150° and the rolling angle is less than 1°.

[0043] Further, the hydrophobic layer is a monomolecular self-assembled layer, the material of the monomolecular self-assembled layer is an organic material SAM, and the molecular structure of the organic material SAM is formed by connecting three characteristic units I, II, and III in sequence, wherein the I unit is selected from Lewis acid or Lewis acid derivatives, the II unit is selected from pyridyl organic ligands, and the III unit is selected from organic hydrophobic groups. In this way, by setting the molecular structure of the organic material SAM, wherein the I unit mainly plays an anchoring role with TCO, the II unit is mainly used to adjust the molecular chain assembly direction and linking role, and the III unit mainly plays a role in isolating external water vapor. Therefore, the organic material SAM with the above structure can make the second region and / or the fourth region better form a super hydrophobic surface with a contact angle greater than 150° and a rolling angle less than 1°.

[0044] Furthermore, the I unit is selected from any one of carboxylic acid, phosphoric acid, boric acid, carboxylic acid derivatives, phosphoric acid derivatives, and boric acid derivatives; the II unit is selected from 4,4-bipyridine or 1,2-di(4-pyridyl)ethane; and the III unit is selected from an alkane group containing 7 to 20 carbon atoms.

[0045] Optionally, the thickness of the hydrophobic layer is 5nm-200nm, preferably 50nm-200nm. Such an arrangement can improve the waterproof performance of the solar cell while substantially not affecting the photoelectric conversion efficiency of the solar cell.

[0046] In one embodiment, the thickness of the first intrinsic amorphous silicon layer 2 is 2nm-10nm, the thickness of the second intrinsic amorphous silicon layer 3 is 2nm-10nm; the thickness of the N-type doping layer 4 is 10nm-30nm, the thickness of the P-type doping layer 5 is 10nm-30nm, the thickness of the first TCO layer 6 is 60nm-90nm, and the thickness of the second TCO layer 7 is 60nm-90nm.

[0047] In the present invention, the first gate and the second gate may contain a metal seed layer in both structures, or one of the structures may contain a metal seed layer. It is understandable that whether or not a metal seed layer is contained is related to the method for preparing the gate. For example, if an electroplating method is used, a metal seed layer needs to be provided, but if a printing method is used, a metal seed layer is not required.

[0048] Specifically, Figure 1 As shown, the first gate includes a first metal seed layer 8 disposed on the first TCO layer 6 and a first metal electrode 10 disposed on the first metal seed layer 8 , and the second gate includes a second metal seed layer 9 disposed on the second TCO layer 7 and a second metal electrode 11 disposed on the second metal seed layer 9 .

[0049] In one embodiment, the thickness of the first metal seed layer 8 is 30nm-300nm, and the thickness of the second metal seed layer 9 is 30nm-300nm. In this way, the thickness of the first metal seed layer 8 and the second metal seed layer 9 can be adjusted to effectively improve the interface bonding force between the first metal seed layer 8 and the second metal seed layer 9 and the silicon wafer 1, and improve the reliability and stability of the first metal electrode 10 and the second metal electrode 11.

[0050] Further, the first metal seed layer 8 is selected from any one of a copper layer, a nickel layer, a titanium layer or a silver layer, and the second metal seed layer 9 is selected from any one of a copper layer, a nickel layer, a titanium layer or a silver layer. It can be understood that the first metal seed layer 8 and the second metal seed layer 9 can be the same or different, preferably the same. Such a configuration is convenient for simplifying the process.

[0051] In one embodiment, the first metal electrode 10 is selected from any one of a copper electrode, a platinum electrode, a silver electrode, and a titanium-nickel electrode, and the second metal electrode 11 is selected from any one of a copper electrode, a platinum electrode, a silver electrode, and a titanium-nickel electrode, preferably a copper electrode; similarly, the first metal electrode 10 and the second metal electrode 11 may be the same or different, preferably the same.

[0052] In one embodiment, the silicon wafer 1 is selected from a P-type single crystal silicon wafer 1 or an N-type single crystal silicon wafer 1 .

[0053] In one embodiment, the first TCO layer 6 and the second TCO layer 7 are selected from transparent conductive oxide layers. Further, the first TCO layer 6 is selected from a single layer structure or a stacked structure of an indium tin oxide layer, an aluminum-doped zinc oxide layer, or a tungsten-doped indium oxide layer; the second TCO layer 7 is selected from a single layer structure or a stacked structure of an indium tin oxide layer, an aluminum-doped zinc oxide layer, or a tungsten-doped indium oxide layer; it can be understood that the stacked structure can be a composite structure of an indium tin oxide layer and an aluminum-doped zinc oxide layer stacked, or a composite structure of an indium tin oxide layer, an aluminum-doped zinc oxide layer, and a tungsten-doped indium oxide layer stacked.

[0054] In one embodiment, the N-type doping layer 4 is selected from a doped amorphous silicon layer or a doped microcrystalline silicon layer; the P-type doping layer 5 is selected from a doped amorphous silicon layer or a doped microcrystalline silicon layer.

[0055] It should be noted that, in the present invention, the first metal electrode 10 and the second metal electrode 11 are used to form the positive and negative electrodes of the heterojunction solar cell, effectively collecting photogenerated carriers; the N-type doped layer 4 and the P-type doped layer 5 form the PN junction and back field of the heterojunction solar cell.

[0056] At the same time, the present invention also provides a method for preparing the heterojunction solar cell as described above, comprising the following steps:

[0057] S1, texturing a silicon wafer 1, and then sequentially forming a first intrinsic amorphous silicon layer 2, an N-type doped layer 4 and a first TCO layer 6 on the front side, and sequentially forming a second intrinsic amorphous silicon layer 3, a P-type doped layer 5 and a second TCO layer 7 on the back side.

[0058] In step S1, the silicon wafer 1 is textured so that a "pyramid" velvet structure is formed on both sides of the silicon wafer 1. The texture making process mainly utilizes the anisotropic corrosion characteristics of silicon in low-concentration alkaline solution. Si and the alkaline solution undergo a series of chemical reactions to form a "pyramid" velvet structure on the surface of the silicon wafer 1.

[0059] In one embodiment, a first intrinsic amorphous silicon layer 2 and an N-type doped layer 4 are sequentially deposited on the front side of the silicon wafer 1 by a plasma enhanced chemical vapor deposition method (PECVD), and a second intrinsic amorphous silicon layer 3 and a P-type doped layer 5 are sequentially deposited on the back side; a first TCO layer 6 is deposited on the surface of the N-type doped layer 4 by a plasma enhanced chemical vapor deposition method (PECVD) or a magnetron sputtering (PVD) method, and a second TCO layer 7 is deposited on the surface of the P-type doped layer 5.

[0060] Furthermore, the material of the first TCO layer 6 is selected from at least one of indium tin oxide, aluminum-doped zinc oxide or tungsten-doped indium oxide; the material of the second TCO layer 7 is selected from at least one of indium tin oxide, aluminum-doped zinc oxide or tungsten-doped indium oxide.

[0061] It should be noted that, in the present invention, the selection of various parameters in the texturing process is not particularly limited, and the specific operation process and process parameters in the PECVD and PVD methods are not particularly limited, so they will not be described in detail here.

[0062] S2, preparing a first metal seed layer 8 on the surface of the first region of the first TCO layer 6, performing a hydrophobic treatment on the second region of the first TCO layer 6, so that the second region is hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°; then preparing a first metal electrode 10 on the surface of the first metal seed layer 8 by electroplating, and preparing a second metal electrode 11 on the third region of the second TCO layer 7 by printing, to obtain a heterojunction solar cell;

[0063] Alternatively, a second metal seed layer 9 is prepared on the surface of the third region of the second TCO layer 7, and a hydrophobic treatment is performed on the fourth region of the second TCO layer 7 to make the fourth region hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°; then a first metal electrode 10 is prepared on the second region of the first TCO layer 6 by a printing method, and a second metal electrode 11 is prepared on the surface of the second metal seed layer 9 by an electroplating method, to obtain a heterojunction solar cell;

[0064] Alternatively, a first metal seed layer 8 is prepared on the surface of the first region of the first TCO layer 6, and a second metal seed layer 9 is prepared on the surface of the third region of the second TCO layer 7. The second region of the first TCO layer 6 and the fourth region of the second TCO layer 7 are hydrophobically treated to make the second region and the fourth region hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°. Then, a first metal electrode 10 is prepared on the surface of the first metal seed layer 8 by electroplating, and a second metal electrode 11 is prepared on the surface of the second metal seed layer 9 to obtain a heterojunction solar cell.

[0065] It can be understood that by utilizing the good hydrophilicity of the first metal seed layer 8 and / or the second metal seed layer 9 and performing hydrophobic treatment on the second region and / or the fourth region, a hydrophilic-hydrophobic composite pattern is formed on the surface of the first TCO layer 6 and / or the surface of the second TCO layer 7, thereby achieving the effect of patterning without the need for photoresist. This method can effectively avoid the problems caused by the use of photoresist, greatly reduce the pressure of environmental pollution, shorten the patterning process, reduce costs, and at the same time improve the waterproof performance of solar cells and improve the reliability of solar cells.

[0066] In one embodiment, the first metal seed layer 8 is prepared on the surface of the first TCO layer 6 by inkjet or printing, and / or the second metal seed layer 9 is prepared on the surface of the second TCO layer 7 by inkjet or printing.

[0067] Furthermore, the material of the first metal seed layer 8 is selected from any one of copper, platinum, silver or nickel; the material of the second metal seed layer 9 is selected from any one of copper, platinum, silver or nickel.

[0068] It should be noted that the area where the first TCO layer 6 is away from the surface of the N-type doped layer 4 and is not covered by the first metal seed layer 8 is the second area, and the area where the second TCO layer 7 is away from the surface of the P-type doped layer 5 and is not covered by the second metal seed layer 9 is the fourth area.

[0069] In the present invention, a mask method is used to perform hydrophobic treatment on the second region and / or the fourth region. Specifically, a mask is provided on the surface of the first TCO layer 6 and the surface of the second TCO layer 7 to obtain a sample, and then a non-mask area on the surface of the semi-finished battery product is hydrophobic treated to make the second region and / or the fourth region hydrophobic.

[0070] The hydrophobic treatment method is selected from chemical vapor deposition, self-assembled monolayer, nano-coating, laser etching or plasma etching, preferably self-assembled monolayer or plasma etching.

[0071] Optionally, when the hydrophobic treatment method is selected from plasma etching, the working gas includes a first gas and a second gas, the first gas is selected from at least one of nitrogen, oxygen or argon, and the second gas is selected from fluorine-containing gas, organosilicon gas or hydrocarbon organic gas, wherein the fluorine-containing gas is selected from sulfur hexafluoride or tetrafluoromethane, the organosilicon gas is selected from hexamethyldisiloxane, and the hydrocarbon organic gas is selected from ethylene and other gases. In this way, the second region and / or the second region can be hydrophobic, and the contact angle is greater than 150° and the rolling angle is less than 1°.

[0072] Furthermore, when the plasma etching method is used, the RF power is 200w-600w, the RF time is 5min-15min, and the gas pressure is 0.01mbar-0.3mbar; such a setting is conducive to controlling the etching effect and obtaining a better super-hydrophobic area.

[0073] Specifically, when the second region and / or the second region are treated with hydrophobicity by plasma etching, the specific steps are as follows: place the sample with the mask in a plasma reactor, introduce a working gas, and then apply an electric field or radio frequency energy to ionize the working gas to form a plasma; under the action of the plasma, the non-masked area on the surface of the sample will be micro-etched, and the roughness will increase, that is, the roughness of the surface of the first TCO layer 6 and / or the surface of the second TCO layer 7 that controls the position of the non-masked area is 50nm-150nm, and this rough structure lays the foundation for enhancing the surface hydrophobicity. At the same time, due to the presence of the second gas, it will also deposit on the surface or react chemically with the surface, changing the chemical composition of the surface, so that the second region and / or the fourth region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound, so that the second region and / or the fourth region has a lower surface energy characteristic, and the surface energy is 10J / m 2 -30J / m 2 , so that the second region and / or the fourth region is hydrophobic, and the contact angle is greater than 150° and the rolling angle is less than 1°.

[0074] Optionally, when the hydrophobic treatment method is selected from the self-assembled monolayer method, the self-assembled monolayer material used is selected from the organic material SAM, and the molecular structure of the organic material SAM is composed of three characteristic units I, II, and III connected in sequence, wherein the I unit is selected from Lewis acid or Lewis acid derivatives, the II unit is selected from pyridyl organic ligands, and the III unit is selected from organic hydrophobic groups; wherein the I unit mainly plays an anchoring role with the TCO, the II unit is mainly used to adjust the assembly direction and linking of the molecular chain, and the III unit mainly plays a role in isolating external water vapor. Therefore, the organic material SAM with the above structure selectively forms a monomolecular self-assembled layer with consistent orientation in the non-mask area on the surface of the first TCO layer 6 and / or the second TCO layer 7 on the front and back sides of the silicon wafer 1, and the alkyl hydrophobic groups of the surface monomolecular layer are distributed outside the plane, so that the second area and / or the fourth area are hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°, which can effectively improve the waterproof performance of the heterojunction solar cell.

[0075] Furthermore, the I unit is selected from any one of carboxylic acid, phosphoric acid, boric acid, carboxylic acid derivatives, phosphoric acid derivatives, and boric acid derivatives; the II unit is selected from 4,4-bipyridine or 1,2-di(4-pyridyl)ethane; and the III unit is selected from an alkane group containing 7 to 20 carbon atoms.

[0076] Specifically, when the second region and / or the fourth region are treated with hydrophobicity by the self-assembled monolayer method, the specific steps are as follows: at room temperature, the sample with the mask is immersed in a solution containing unit I for 1h-2h, taken out, rinsed with ethanol, and dried by nitrogen purge, and then immersed in a solution containing unit II for 2mim-30min, taken out, rinsed with ethanol, and dried by nitrogen purge, and then immersed in a solution containing unit III for 2min-30min, taken out, rinsed with ethanol, removed the mask, and dried by nitrogen purge, so that the second region and / or the fourth region are hydrophobic, and a hydrophobic-treated sample is obtained.

[0077] Furthermore, the concentration of the solution containing unit I is 0.01mmol / L-0.5mmol / L, the concentration of the solution containing unit II is 0.05mmol / L-1mmol / L, and the concentration of the solution containing unit III is 0.05mmol / L-1mmol / L.

[0078] In one embodiment, the solvent in the solution containing unit I, the solution containing unit II, and the solution containing unit III is an alcohol solvent, such as ethanol.

[0079] It should be noted that in the present invention, the contact angle of the second region and / or the fourth region is greater than 150°, and the rolling angle is less than 1°, so that the second region and / or the fourth region are super-hydrophobic regions, and the super-hydrophobic region has the characteristic of low surface energy, which can increase the contact angle between the surface and water molecules. According to Young's equation, the increase in contact angle helps to improve hydrophobicity. When the first metal electrode 10 and the second metal electrode 11 are prepared by electroplating, when the electroplating solution contacts the super-hydrophobic region, the region can capture air to form a layer of air cushion, so that the electroplating solution presents a state of approximate spherical shape on its surface, and the contact area decreases accordingly. At this time, the electroplating solution contacts the air cushion, rather than directly contacting the second region and / or the fourth region, which greatly reduces the interaction between the electroplating solution and the second region and / or the fourth region, so that the electroplating solution is basically not in contact with the second region and / or the fourth region, so that the hydrophobic region basically does not have the phenomenon of depositing metal electrodes.

[0080] Therefore, the method for preparing the heterojunction solar cell of the present invention is simple to operate, does not require the use of photoresist, is green and environmentally friendly, and has low cost.

[0081] It should be noted that in the present invention, Young's equation is γsg=γsl+γlgcosθ, wherein γsg represents the surface tension of the solid-gas interface, γsl represents the surface tension of the solid-liquid interface, γlg represents the surface tension of the liquid-gas interface, and θ represents the contact angle.

[0082] Specifically, the steps of preparing the first metal electrode 10 on the surface of the first metal seed layer 8 by electroplating, and / or preparing the second metal electrode 11 on the surface of the second metal seed layer 9 by electroplating are as follows: placing one side or all of the hydrophobic treated silicon wafer 1 in an electroplating solution for electroplating, preparing the first metal electrode 10 on the surface of the first metal seed layer 8, and / or preparing the second metal electrode 11 on the surface of the second metal seed layer 9.

[0083] In one embodiment, the electroplating solution includes a main metal salt, an acid, an additive or a complexing agent, etc., wherein the main metal salt is selected from at least one of copper salts, platinum salts, silver salts, and nickel salts, and further the main metal salt is selected from copper sulfate, copper chloride, nickel sulfate or silver nitrate; the acid is preferably sulfuric acid, the additive may be a brightener, an inhibitor or a leveling agent, and the complexing agent is preferably ethylenediaminetetraacetic acid (EDTA).

[0084] Furthermore, the mass fraction of the main metal salt in the electroplating solution is 1%-3%.

[0085] In one embodiment, the material of the first metal electrode 10 is selected from any one of copper, platinum, silver or nickel; the material of the second metal electrode 11 is selected from any one of copper, platinum, silver or nickel.

[0086] In one embodiment, when the material of the first metal electrode 10 and the second metal electrode 11 is selected from copper, the method for preparing the heterojunction solar cell further comprises: electroplating or chemically plating the surface of the first metal electrode 10 and the second metal electrode 10 to form an electroplating layer, wherein the material of the electroplating layer is selected from at least one of tin, nickel, and zinc. In this way, the oxidation resistance of the first metal electrode 10 and the second metal electrode 11 can be enhanced.

[0087] Therefore, the heterojunction solar cell of the present invention has the characteristics of good water resistance, high reliability and self-cleaning, and the preparation method is simple, no photoresist is required, and it is green, environmentally friendly and low in cost.

[0088] Hereinafter, the heterojunction solar cell and the preparation method thereof will be further described by the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0089] It should be noted that the contact angles involved in the embodiments and comparative examples of the present invention are obtained by a contact angle meter, the rolling angles are measured by a contact angle tester, the roughness is measured by an atomic force microscope and a step profiler, and the surface energy is measured by Young's equation.

[0090] Example 1

[0091] A P-type single crystal silicon wafer is subjected to texturing treatment to obtain a P-type single crystal silicon wafer with a pyramid light trapping structure on both sides; a plasma enhanced chemical vapor deposition method (PECVD) is used to passivate and dope the two sides of the P-type single crystal silicon wafer after texturing, so that a first intrinsic amorphous silicon layer and an N-type doped amorphous silicon layer are deposited in sequence on the front side of the P-type single crystal silicon wafer, and a second intrinsic amorphous silicon layer and a P-type doped amorphous silicon layer are deposited in sequence on the back side; and then a physical vapor deposition (PVD) method is used to deposit the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer on the surface of the N-type doped amorphous silicon layer and the second intrinsic amorphous silicon layer on the surface of the P-type doped amorphous silicon layer. The first indium tin oxide layer and the second indium tin oxide layer are formed by surface deposition; then the corresponding first copper seed layer and the second copper seed layer are prepared on the surfaces of the first indium tin oxide layer and the second indium tin oxide layer by screen printing process, to obtain a battery semi-finished product, wherein the thickness of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are both 4nm, the thickness of the N-type doped amorphous silicon layer and the P-type doped amorphous silicon layer are both 14nm, the thickness of the first indium tin oxide layer and the second indium tin oxide layer are both 80nm, and the thickness of the first copper seed layer and the second copper seed layer are both 100nm.

[0092] A mask is covered on the surface of a semi-finished battery product so that the mask is in close contact with the surface of the semi-finished battery product, and then placed in a plasma reactor, and a working gas is introduced, and then a radio frequency is applied to ionize the working gas to form plasma, and the non-masked area on the surface of the first indium tin oxide layer and the second indium tin oxide layer is etched to form a rough structure. At the same time, in this process, under the action of plasma, a hydrophobic area is deposited or reacted on the surface of the formed rough structure, so that the second area and the fourth area are both hydrophobic, and the mask is removed to obtain a semi-finished battery product after hydrophobic treatment, wherein the working gas includes nitrogen and carbon tetrafluoride, the radio frequency power is 300W, the radio frequency time is 15min, the gas pressure is 0.01mbar, the roughness of the rough structure formed on the surface of the first indium tin oxide layer and the second indium tin oxide layer is 100nm, and the surface energy of the second area and the fourth area is 15J / m 2 , the contact angle is 160 degrees and the rolling angle is 0.8 degrees.

[0093] The battery semi-finished product after hydrophobic treatment is placed in a copper electroplating solution for electroplating, and a corresponding first copper electrode and a second copper electrode are prepared on the surface of the first copper seed layer and the surface of the second copper seed layer to obtain a heterojunction solar cell, wherein the copper electroplating solution includes copper sulfate, sulfuric acid and ethylenediaminetetraacetic acid, and the mass fraction of copper sulfate in the copper electroplating solution is 2%.

[0094] Example 2

[0095] The difference between Example 2 and Example 1 is that the working gas includes oxygen and silicon tetrafluoride, the RF power is 400 W, the RF time is 20 min, the roughness of the rough structure formed on the surface of the first indium tin oxide layer and the second indium tin oxide layer is 120 nm, and the surface energy of the second region and the fourth region is 10 J / m 2 , the contact angle is 170°, the rolling angle is 0.6°, and the other conditions are the same to obtain a heterojunction solar cell.

[0096] Example 3

[0097] The only difference between Example 3 and Example 1 is that the semi-finished battery product after hydrophobic treatment is placed in a copper electroplating solution for electroplating, and after the corresponding first copper electrode and second copper electrode are prepared on the surface of the first copper seed layer and the surface of the second copper seed layer, chemical plating is carried out in a tin methanesulfonate solution to form a tin layer, and the other conditions are the same to obtain a heterojunction solar cell.

[0098] Example 4

[0099] Compared with Example 1, Example 4 differs only in that a mask is covered on the surface of the battery semi-finished product so that the mask is in close contact with the surface of the battery semi-finished product, and then the battery is immersed in an ethanol solution containing carboxylic acid at a concentration of 0.1 mmol / L for 1 hour at room temperature, taken out, rinsed with ethanol, and dried by nitrogen purge, and then immersed in an ethanol solution containing pyridine at a concentration of 0.2 mmol / L for 15 minutes, taken out, rinsed with ethanol, and dried by nitrogen purge, and then immersed in an ethanol solution containing an alkane group with a carbon number of 15 at a concentration of 0.2 mmol / L for 10 minutes, taken out, rinsed with ethanol, removed, and dried by nitrogen purge, so that a hydrophobic layer is formed on the surface of the first indium tin oxide layer and the second indium tin oxide layer not covered with the first copper seed layer and the second copper seed layer, respectively, to obtain a battery semi-finished product after hydrophobic treatment, wherein the thickness of the hydrophobic layer is 6 nm, the contact angle is 160°, the rolling angle is 0.8°, and the other conditions are the same, to obtain a heterojunction solar cell.

[0100] Example 5

[0101] Compared with Example 4, Example 5 differs only in that an ethanol solution of boric acid with a concentration of 0.2 mmol / L is used instead of the ethanol solution containing carboxylic acid with a concentration of 0.1 mmol / L, an ethanol solution of 4,4-bipyridine with a concentration of 0.3 mmol / L is used instead of the ethanol solution containing pyridine with a concentration of 0.2 mmol / L, and an ethanol solution containing an alkane group with a carbon number of 20 with a concentration of 0.3 mmol / L is used instead of the ethanol solution containing an alkane group with a carbon number of 15 with a concentration of 0.2 mmol / L, and other conditions are the same, so that a hydrophobic layer is formed on the surfaces of the first indium tin oxide layer and the second indium tin oxide layer not covered with the first copper seed layer and the second copper seed layer, respectively, to obtain a battery semi-finished product after hydrophobic treatment, wherein the thickness of the hydrophobic layer is 6 nm, the contact angle is 160°, the rolling angle is 0.8°, and the other conditions are the same, to obtain a heterojunction solar cell.

[0102] Example 6

[0103] Example 6 Compared with Example 1, a second copper seed layer is prepared on the surface of the second indium tin oxide layer by a screen printing process to obtain a battery semi-finished product; a mask is covered on the surface of the battery semi-finished product so that the mask is in close contact with the surface of the battery semi-finished product, and then placed in a plasma reactor, and a working gas is introduced, and then radio frequency is applied to ionize the working gas to form a plasma, and the non-mask area on the surface of the second indium tin oxide layer is etched to form a rough structure. At the same time, in this process, under the action of plasma, a hydrophobic area is deposited or reacted on the surface of the rough structure formed, so that the fourth area is hydrophobic, and the mask is removed to obtain a battery semi-finished product after hydrophobic treatment; then a first gate slurry is printed on the first area surface of the first indium tin oxide layer of the battery semi-finished product after hydrophobic treatment by a screen printing method, and a first copper electrode is formed by sintering, wherein the first gate slurry is pure copper slurry, and the mass fraction of copper powder in the first gate slurry is 95%. Finally, the second indium tin oxide layer of the battery semi-finished product after hydrophobic treatment is placed in a copper electroplating solution for electroplating, and a second copper electrode is prepared on the surface of the second copper seed layer to obtain a heterojunction solar cell.

[0104] Comparative Example 1

[0105] Comparative Example 1 is different from Example 1 only in that the working gas includes nitrogen and oxygen, the RF power is 100 W, the RF time is 5 min, the gas pressure is 0.03 mbar, and the surface energy of the second area and the fourth area is 40 J / m 2 , the contact angle is 140°, the rolling angle is 10°, and the other conditions are the same to obtain a heterojunction solar cell.

[0106] Comparative Example 2

[0107] Comparative Example 2 is different from Example 1 in that the working gas includes nitrogen and oxygen, the RF power is 80 W, the RF time is 5 min, the gas pressure is 0.03 mbar, and the surface energy of the second and fourth regions is 50 J / m 2 , the contact angle is 120°, the rolling angle is 30°, and the other conditions are the same to obtain a heterojunction solar cell.

[0108] Comparative Example 3

[0109] Comparative Example 3 is different from Example 1 only in that the working gas includes nitrogen and oxygen, the RF power is 50 W, the RF time is 3 min, the gas pressure is 0.03 mbar, and the surface energy of the second and fourth regions is 60 J / m 2 , the contact angle is 90°, the rolling angle is 60°, and the other conditions are the same to obtain a heterojunction solar cell.

[0110] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A heterojunction solar cell, characterized in that: The heterojunction solar cell comprises: A silicon wafer, wherein the silicon wafer has a front side and a back side that are arranged opposite to each other; A first intrinsic amorphous silicon layer, an N-type doped layer, a first TCO layer and a first gate are sequentially stacked on the front side of the silicon wafer; A second intrinsic amorphous silicon layer, a P-type doped layer, a second TCO layer and a second gate are sequentially stacked on the back side of the silicon wafer; The first gate is hydrophilic, the first TCO layer includes a first region and a second region, the first gate is arranged in the first region, the second region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°; and / or the second gate is hydrophilic, the second TCO layer includes a third region and a fourth region, the second gate is arranged in the third region, the fourth region is hydrophobic, and the contact angle is greater than 150°, and the rolling angle is less than 1°.

2. The heterojunction solar cell according to claim 1, characterized in that: The roughness of the surface of the first TCO layer at the second region is selected from 50 nm to 150 nm, and the second region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound; And / or, the surface roughness of the second TCO layer at the fourth region is selected from 50 nm to 150 nm, and the fourth region contains a hydrophobic compound, wherein the hydrophobic compound is selected from a fluorine-containing compound or a silicon-containing compound.

3. The heterojunction solar cell according to claim 2, characterized in that: The surface energy of the second region is selected from 10 J / m 2 -30J / m 2 ; And / or, the surface energy of the fourth region is selected from 10 J / m 2 -30J / m 2 .

4. The heterojunction solar cell according to claim 1, characterized in that: A surface of the first TCO layer at the second region and / or a surface of the second TCO layer at the fourth region has a hydrophobic layer.

5. The heterojunction solar cell according to claim 4, characterized in that: The hydrophobic layer is a monomolecular self-assembled layer, the material of the monomolecular self-assembled layer is an organic material SAM, and the molecular structure of the organic material SAM is composed of three characteristic units I, II, and III connected in sequence, wherein the I unit is selected from Lewis acid or Lewis acid derivatives, the II unit is selected from pyridyl organic ligands, and the III unit is selected from organic hydrophobic groups.

6. The heterojunction solar cell according to claim 4, characterized in that: The thickness of the hydrophobic layer is 5nm-200nm.

7. A method for preparing a heterojunction solar cell, characterized in that: The steps include: The silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side; A first metal seed layer is prepared on the surface of the first region of the first TCO layer, and a second region of the first TCO layer is subjected to a hydrophobic treatment to make the second region hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°; then a first metal electrode is prepared on the surface of the first metal seed layer by electroplating, and a second metal electrode is prepared on the third region of the second TCO layer by printing to obtain a heterojunction solar cell; Alternatively, the silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side; A second metal seed layer is prepared on the surface of the third region of the second TCO layer, and a fourth region of the second TCO layer is subjected to a hydrophobic treatment to make the fourth region hydrophobic, wherein a contact angle is greater than 150° and a rolling angle is less than 1°; then a first metal electrode is prepared on the second region of the first TCO layer by a printing method, and a second metal electrode is prepared on the surface of the second metal seed layer by an electroplating method to obtain a heterojunction solar cell; Alternatively, the silicon wafer is textured, and then a first intrinsic amorphous silicon layer, an N-type doped layer and a first TCO layer are sequentially formed on the front side, and a second intrinsic amorphous silicon layer, a P-type doped layer and a second TCO layer are sequentially formed on the back side; A first metal seed layer is prepared on the surface of the first area of ​​the first TCO layer, and a second metal seed layer is prepared on the surface of the third area of ​​the second TCO layer. The second area of ​​the first TCO layer and the fourth area of ​​the second TCO layer are hydrophobicized to make the second area and the fourth area hydrophobic, wherein the contact angle is greater than 150° and the rolling angle is less than 1°. Then, a first metal electrode is prepared on the surface of the first metal seed layer by electroplating, and a second metal electrode is prepared on the surface of the second metal seed layer to obtain a heterojunction solar cell.

8. The method for preparing a heterojunction solar cell according to claim 7, characterized in that: The hydrophobic treatment method is selected from chemical vapor deposition, self-assembled monolayer, nano-coating, laser etching or plasma etching.

9. The method for preparing a heterojunction solar cell according to claim 8, characterized in that: When the hydrophobic treatment method is selected from plasma etching, the working gas includes a first gas and a second gas, the first gas is selected from at least one of nitrogen, oxygen or argon, and the second gas is selected from fluorine-containing gas, organic silicon gas or hydrocarbon organic gas.

10. The method for preparing a heterojunction solar cell according to claim 8, characterized in that: When the hydrophobic treatment method is selected from the self-assembled monolayer method, the self-assembled monolayer material used is selected from the organic material SAM, and the molecular structure of the organic material SAM is composed of three characteristic units I, II, and III connected in sequence, wherein the I unit is selected from Lewis acid or Lewis acid derivatives, the II unit is selected from pyridyl organic ligands, and the III unit is selected from organic hydrophobic groups.

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