CN112652671A - Texturing method, monocrystalline silicon wafer and monocrystalline silicon solar cell - Google Patents

Texturing method, monocrystalline silicon wafer and monocrystalline silicon solar cell Download PDF

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CN112652671A
CN112652671A CN202011629109.3A CN202011629109A CN112652671A CN 112652671 A CN112652671 A CN 112652671A CN 202011629109 A CN202011629109 A CN 202011629109A CN 112652671 A CN112652671 A CN 112652671A
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monocrystalline silicon
texturing
silicon wafer
solution
mass concentration
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丁超
童洪波
李华
刘继宇
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Taizhou Longi Solar Technology Co Ltd
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Taizhou Lerri Solar Technology Co Ltd
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Priority to PCT/CN2021/134041 priority patent/WO2022142943A1/en
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    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0236—Special surface textures
    • H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
    • H—ELECTRICITY
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
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    • Y02E10/547—Monocrystalline silicon PV cells
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Abstract

The application provides a texturing method, a monocrystalline silicon piece and a monocrystalline silicon solar cell, and relates to the technical field of photovoltaics. The method comprises the following steps: alkali texturing is carried out on the monocrystalline silicon piece; pickling the monocrystalline silicon wafer subjected to alkali texturing for the first time; carrying out metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution to form nano holes on the pyramid textured surface; the content of metal ions in the texturing solution is 0.0001-0.001 mol/L; performing primary demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing; pickling the monocrystalline silicon wafer subjected to the first demetallization for the second time; modifying the monocrystalline silicon wafer after the second pickling by using a modifying solution to expand the nanometer holes; and (3) performing secondary demetallization on the reamed monocrystalline silicon wafer by adopting a water bubbling mode containing ozone. The metal ion concentration is small, the size of the formed nanometer hole is small, and the reflectivity is low. The bubbles generate vibration, the ozone and the metal ions generate chemical reaction, the metal ions are less remained in the holes, the compounding is less, and the power generation efficiency is high.

Description

Texturing method, monocrystalline silicon wafer and monocrystalline silicon solar cell
Technical Field
The invention relates to the technical field of photovoltaics, in particular to a texturing method, a monocrystalline silicon piece and a monocrystalline silicon solar cell.
Background
The monocrystalline silicon piece is subjected to texturing, and the nanometer holes are formed in the textured surface, so that the surface reflection can be further reduced, and the utilization rate of incident light is increased.
However, in the prior art, after the nano holes are formed on the pyramid texture of the monocrystalline silicon wafer, the power generation efficiency of the monocrystalline silicon solar cell is reduced.
Disclosure of Invention
The invention provides a texturing method, a monocrystalline silicon piece and a monocrystalline silicon solar cell, and aims to solve the problem that the power generation efficiency of the monocrystalline silicon solar cell is reduced after a nano hole is formed in the textured surface of the monocrystalline silicon piece.
According to a first aspect of the present invention, there is provided a texturing method comprising the steps of:
carrying out alkali texturing on the monocrystalline silicon wafer to form a pyramid textured surface;
carrying out primary acid washing on the monocrystalline silicon wafer subjected to alkali texturing;
carrying out metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution to form nano holes on the pyramid textured surface; the content of metal ions in the texturing solution is 0.0001-0.001 mol/L;
performing primary demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing;
carrying out acid washing on the monocrystalline silicon wafer subjected to the first demetallization for the second time;
modifying the monocrystalline silicon wafer after the second pickling by using a modifying solution to expand the nanometer holes;
and (3) performing secondary demetallization on the reamed monocrystalline silicon wafer by adopting a water bubbling mode containing ozone.
In the embodiment of the invention, in the metal ion-assisted texturing step, the content of metal ions is 0.0001-0.001mol/L, the concentration of the metal ions is lower, the accumulation phenomenon of the metal ions on the surface of the pyramid textured surface is effectively reduced, the metal ions are more uniformly distributed, the uniformity of subsequent etching is also favorably ensured, meanwhile, the content of the metal ions is not too low, the fluctuation on the surface of a monocrystalline silicon wafer is avoided, and the generated nano holes are not too small. And the nano holes formed by the metal ions with the content cannot be connected into a whole to cause the holes to be too large, the size of the formed nano holes is smaller, and the reflectivity of the surface of the monocrystalline silicon piece can be effectively reduced. And reaming is also carried out after metal ion-assisted texturing, so that the obtained nano holes are proper in size, and the reflectivity of the surface of the monocrystalline silicon piece can be effectively reduced. Meanwhile, in the metal ion texturing process, the concentration of metal ions is low, so that the metal ions or metal impurities in the holes are low, and the metal ions or metal impurities in the holes are easy to remove. In the second demetallization process, the bubbling can generate vibration, and metal ions or metal impurities are loosened from the surface of the monocrystalline silicon wafer in the holes in a physical mode to remove the metal ions or the metal impurities; simultaneously, the water that contains ozone and the metal ion or the metallic impurity in the hole take place chemical reaction, make the adhesion or the absorption on metal ion or metallic impurity and monocrystalline silicon piece's surface receive the influence, and above-mentioned physical shock also can be to the influence of adsorbing between metal ion or metallic impurity and the monocrystalline silicon piece, the water that has catalyzed ozone and metal ion or metallic impurity also take place chemical reaction, make through the water that contains ozone of liquid phase, discharge metal ion or metallic impurity in the hole, metal ion or metallic impurity basically can not remain in the hole, and then the complex that metal ion or metallic impurity arouse obviously reduces, power generation efficiency has been promoted.
Optionally, the modifying liquid is a mixed solution of hydrogen peroxide, hydrofluoric acid and ammonium fluoride; wherein, in the modifying liquid, H2O2The mass concentration of (A) is 2-10%, the mass concentration of HF is 0.3-2%, and NH4The mass concentration of F is 1.5-10%.
Optionally, in the second demetallization, the water containing ozone is bubbled through nitrogen; and/or, ultrasonically bubbling the water containing ozone.
Optionally, the metal ions are selected from at least one of silver ions, copper ions, nickel ions, platinum ions, palladium ions or gold ions.
Optionally, in the second demetallization, the water containing ozone contains hydrogen peroxide.
Optionally, in the modification, the modification temperature is 8-40 ℃, and the modification time is 90-480 s; the diameter of the modified nanometer hole is 40-130nm, and the depth is 30-120 nm.
Optionally, the texturing solution further comprises hydrofluoric acid and hydrogen peroxide; wherein, in the texturing solution, the mass concentration of HF is 5-15%, and H2O2The mass concentration of the nano-pores is 0.2-2%, the texture-making temperature is 30-35 ℃, the reaction time is 90-480s, the diameter of the nano-pores obtained by metal ion assisted texture-making is 30-120nm, and the depth is 20-100 nm.
Optionally, the solution subjected to the first demetallization treatment comprises ammonium hydroxide, hydrogen peroxide and deionized water, wherein in the solution subjected to the first demetallization treatment, NH4OH mass concentration of 1-5%, H2O2The mass concentration of the catalyst is 1-5%, the demetallization temperature is normal temperature, and the reaction time is 90-450 s.
Optionally, the solution in the alkaline texturing step comprises sodium hydroxide, an additive and deionized water, wherein in the alkaline texturing solution, the mass concentration of NaOH is 1-5%, the texturing temperature is 80-90 ℃, the reaction time is 5-10min, the reflectivity of the pyramid textured surface is 9-15%, and the size of the pyramid textured surface is 1-5 μm.
Optionally, in the first acid washing step, a nitric acid solution is used for acid washing, and in the first acid washing solution, HNO is added3The mass concentration of the acid is 1-10%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s;
in the second acid washing step, mixed solution of hydrofluoric acid and hydrochloric acid is adopted for acid washing, wherein in the second acid washing solution, the mass concentration of HF and HCl is 2-8%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s.
Optionally, after the second demetallization step, performing third acid washing on the monocrystalline silicon wafer by using a mixed solution of hydrofluoric acid and hydrochloric acid, wherein in the third acid washing solution, the mass concentrations of HF and HCl are both 2-8%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s;
the method further comprises a drying treatment of the monocrystalline silicon wafer after the third pickling step.
Optionally, after each step, deionized water is used to clean the monocrystalline silicon wafer at least once.
According to a second aspect of the present invention, there is provided a single crystal silicon wafer, at least one side surface of which is a textured surface; the texture surface has a pyramid shape, and nano holes are distributed on the surface of the pyramid; the chroma value L of the suede is 10-70.
Optionally, the size of the pyramid is 1-5 μm; the diameter of the nanometer hole is 40-130nm, and the depth is 30-120 nm;
the cross section of the nanometer hole is square.
Optionally, the chroma value L of the suede is 20-60.
According to a third aspect of the present invention, there is provided a monocrystalline silicon solar cell comprising a monocrystalline silicon wafer produced by the texturing method as described in any one of the preceding claims.
Optionally, the monocrystalline silicon solar cell further includes a passivation antireflection film layer on a light-facing surface of the monocrystalline silicon wafer; the passivated antireflection film layer comprises a silicon nitride layer and a silicon oxide layer which are arranged in a stacked mode; the silicon oxide layer is far away from the monocrystalline silicon piece.
Optionally, the thickness of the passivated antireflection film layer is 50-200 nm;
the thickness of the silicon nitride layer is 50-70 nm; the refractive index of the silicon nitride layer is 1.9-2.4;
the thickness of the silicon oxide layer is less than or equal to 50 nm; the refractive index of the silicon oxide layer is less than 1.8.
Optionally, the silicon nitride layer is of one or more layers;
when the silicon nitride layer has a multilayer structure, the refractive index of each layer of silicon nitride decreases in order from the direction close to the single crystal silicon wafer to the direction away from the single crystal silicon wafer.
The monocrystalline silicon wafer and the monocrystalline silicon solar cell have the same or similar beneficial effects as the texturing method, and are not described again to avoid repetition.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive exercise.
FIG. 1 shows a flow chart of a method of making wool in an embodiment of the invention;
FIG. 2 is a partially enlarged photograph of a single crystal silicon wafer according to an embodiment of the present invention;
FIG. 3 is a magnified photograph of a partial cross-section of a single crystal silicon wafer according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The inventor of the present invention finds that, in the prior art, after the nano-holes are formed on the textured surface of the monocrystalline silicon wafer, the main reason for the reduction of the power generation efficiency of the monocrystalline silicon solar cell is as follows: after metal ion assisted texturing, on one hand, the nanometer holes have larger shape difference, and the texture structure is not optimized; on the other hand, metal ions or metal impurities remained on the surface of the monocrystalline silicon piece are easy to remove, but the metal ions or the metal impurities remained in the holes are not easy to remove, and the metal ions or the metal impurities remained in the holes are easy to compound in the power generation process, so that the power generation efficiency is reduced.
In the embodiment of the present invention, referring to fig. 1, fig. 1 shows a flow chart of steps of a texturing method in the embodiment of the present invention. The method comprises the following steps:
and step S1, alkali texturing is carried out on the monocrystalline silicon wafer to form a pyramid textured surface.
Optionally, the solution in the alkaline texturing step comprises sodium hydroxide (NaOH), an additive and deionized water, wherein in the alkaline texturing solution, the mass concentration of the NaOH is 1-5%, the texturing temperature is 80-90 ℃, the reaction time is 5-10min, the reflectivity of the obtained pyramid textured surface is 9-15%, and the size of the pyramid textured surface is 1-5 μm. The additive here may be a catalyst for promoting the alkali solution texturing, or the like. The present invention is not particularly limited in this regard. For example, the additive herein may be isopropyl alcohol or the like.
The specific components of the alkali texturing solution, the alkali texturing time and the like, the invention is not limited to the components, and the components can be set by a person skilled in the art according to actual needs.
The mass concentration in the present invention is the mass ratio of the active ingredient in the solution prepared. For example, the alkali texturing solution is a prepared solution, and the mass concentration of the effective component NaOH in the prepared solution alkali texturing solution is 1-5%.
Step S2, the monocrystalline silicon piece after alkali texturing is subjected to first acid washing.
The primary acid washing mainly aims at: oxidizing the surface of the silicon wafer, and neutralizing the alkali texturing solution on the surface of the monocrystalline silicon wafer. The solution, duration and the like of the first acid washing can be set by those skilled in the art according to actual needs.
It should be noted that, between the step S1 and the step S2, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S1.
Optionally, in the first acid-washing step,nitric acid (HNO) may be used3) Pickling the solution, first pickling the solution with HNO3The mass concentration of the acid is 1-10%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s. In the first acid washing, the nitric acid solution can oxidize the surface of the silicon wafer so as to form uniform nano holes on the surface of the silicon wafer in the next step.
Step S3, metal ion-assisted texturing is carried out on the monocrystalline silicon wafer after the primary acid washing by using a texturing solution so as to form nano holes on the pyramid textured surface; the content of metal ions in the texturing solution is 0.0001-0.001 mol/L.
When a monocrystalline silicon wafer is immersed in a texturing solution containing metal ions, metal ions obtain electrons from a valence band of silicon and are simultaneously injected into holes so as to be converted into metal elementary substance particles, the metal elementary substance particles are deposited on a pyramid textured structure on the surface of the monocrystalline silicon wafer, the silicon is oxidized in order to keep charge conservation, the oxidized silicon is corroded by acid in the texturing solution, such as hydrofluoric acid (HF), each metal ion and a local silicon surface in contact with the metal ion can be regarded as a miniature electrochemical cell, and the electronegativity of the metal elementary substance particles is stronger than that of the silicon, so that the electrons are continuously attracted from the silicon (can be regarded as a cathode). The texturing solution also contains an oxidant, such as hydrogen peroxide (H)2O2) The oxidation effect can be enhanced. Holes are continuously injected into the silicon through the metal to be oxidized, and the silicon wafer surface in contact with the metal particles is continuously deprived of electrons to be oxidized and continues to be corroded by HF (which can be regarded as an anode). The corrosion speed of the surface of the silicon wafer contacted with metal is high, and the corrosion speed of the surface without the contact of metal particles is very slow, so that a structure with an uneven surface is formed, and a nano-pore structure is formed along with the further promotion of the reaction process.
The content of metal ions in the texturing solution is 0.0001-0.001mol/L, and compared with the situation that the content of the metal ions in the texturing solution in the prior art is far larger than 0.001mol/L, the content of the metal ions in the texturing solution is lower in the application, the accumulation phenomenon of the metal ions on the surface of the pyramid textured surface is effectively reduced, the metal ions are distributed more uniformly, the uniformity of subsequent etching is also favorably ensured, meanwhile, the content of the metal ions is not too low, fluctuation cannot be generated on the surface of a monocrystalline silicon wafer, and generated nano holes are not too small. And the nano holes formed by the metal ions with the content cannot be connected into a whole, the size of the formed nano holes is small, and the reflectivity of the surface of the monocrystalline silicon piece can be effectively reduced. Meanwhile, in the metal ion texturing process, the concentration of metal ions is low, so that the metal ions or metal impurities in the holes are low, and the metal ions or metal impurities in the holes are easy to remove.
It should be noted that, between the step S2 and the step S3, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S2.
Optionally, the metal ions are at least one selected from silver ions, copper ions, nickel ions, platinum ions, palladium ions, or gold ions, and the metal ions are more in variety.
Optionally, in the metal ion-assisted texturing step, the texturing solution further includes hydrofluoric acid (HF) and hydrogen peroxide (H) in addition to the metal ions2O2). Wherein, in the texturing solution, the mass concentration of HF is 5-15%, and H2O2The mass concentration of the catalyst is 0.2-2%, the wool making temperature is 30-35 ℃, and the reaction time is 90-480 s.
Optionally, the diameter of the nano-pores prepared in the metal ion-assisted texturing step is 30-120nm, and the depth is 20-100 nm. The content of metal ions is relatively low, so that the size of the prepared nano holes is small, and the reflectivity of the surface of the monocrystalline silicon piece can be effectively reduced.
The specific components of the texturing solution are not limited in the invention, and can be adjusted according to different actual conditions.
And step S4, performing first demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing.
The primary demetallization treatment has the main function of removing metal ions or metal impurity residues of the monocrystalline silicon wafer except for the nano holes.
In the first demetallization process, organic impurities and the like having an influence on the power generation efficiency may be removed.
It should be noted that, between the step S3 and the step S4, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S3.
Optionally, the solution in the first demetalling step comprises ammonium hydroxide (NH)4OH), hydrogen peroxide and deionized water, wherein, in the solution of the first demetallization treatment, NH is added4OH mass concentration of 1-5%, H2O2The mass concentration of the catalyst is 1-5%, the demetallization temperature is normal temperature, and the reaction time is 90-450 s.
And step S5, carrying out acid washing on the monocrystalline silicon wafer subjected to the first demetallization for the second time.
The second acid washing is to clean the first demetallization solution on the surface of the monocrystalline silicon piece.
It should be noted that, between the step S4 and the step S5, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S4.
Optionally, in the second acid washing step, a mixed solution of hydrofluoric acid and hydrochloric acid is used for acid washing, wherein in the second acid washing solution, the mass concentrations of HF and HCl are both 2-8%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s.
And step S6, modifying the monocrystalline silicon wafer after the second pickling by using a modification liquid so as to expand the nanometer holes.
The modification solution mainly has the function of modifying and enlarging the shape of the nano-pores formed in step S3, and the modification solution can be divided into an alkaline modification solution and an acidic modification solution. For example, the embodiment of the invention can adopt the acidic modification liquid to modify and expand the nanometer hole. The specific components of the modifying liquid are not particularly limited.
And reaming is also carried out after metal ion-assisted texturing, so that the obtained nano holes are proper in size, and the reflectivity of the surface of the monocrystalline silicon piece can be effectively reduced.
It should be noted that, between the step S5 and the step S6, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S5.
Optionally, the modifying liquid is hydrogen peroxide, hydrofluoric acid, ammonium fluoride (NH)4F) The mixed solution of (1). Wherein, in the modifying liquid, H2O2The mass concentration of (A) is 2-10%, the mass concentration of HF is 0.3-2%, and NH4The mass concentration of F is 1.5-10%. Ammonium fluoride is used as a buffer in the modification liquid, so that the modification liquid can keep stable and controllable etching rate at each reaction position, modification and hole expansion reactions are not too violent, holes cannot be expanded too much, and the sizes of the nano holes are uniform after hole expansion. The size of the nanometer hole after reaming is uniform, so that the monocrystalline silicon piece has no color difference in each angle range of visual angles, has consistent visual effect in each angle range of visual angles, and is more attractive. For example, referring to fig. 2, fig. 2 shows a partially enlarged photograph of a single crystal silicon wafer according to an embodiment of the present invention. The photo is a picture of a real object which is approximately amplified by 3 ten thousand times, and the nano holes on the pyramid suede are basically consistent in size and uniform in steps as can be seen from the photo.
According to the invention, through the steps of modification, hole expansion and the like, the cross section of the formed nano hole is square, while the cross section of the nano hole formed in the prior art is arc-shaped, compared with the cross section of the nano hole in the prior art which is arc-shaped, the cross section is square in the application, the square nano hole reflects light weakly, and the light absorption capacity can be improved. For example, referring to fig. 3, fig. 3 shows a magnified partial cross-sectional photograph of a single crystal silicon wafer according to an embodiment of the present invention. The photo is a picture of a real object which is approximately magnified by 10 ten thousand times, and as can be seen from the photo, the cross section of the nano holes on the pyramid suede is square, and more particularly, is rectangular.
The modification can also make the water containing ozone in the subsequent step easily enter the nanometer holes in the form of bubbles.
Optionally, the modification temperature is 8-40 ℃, and the modification time is 90-480 s; the diameter of the modified nano hole is 40-130nm, the depth is 30-120nm, the size of the modified nano hole is proper, the band gap of the energy band is wide, the absorption of infrared light is enlarged, the light trapping effect is improved, and the short wave reflectivity is reduced.
And step S7, performing secondary demetallization on the single crystal silicon wafer after hole expansion by adopting a water bubbling mode containing ozone.
In the prior art, only the first demetallization in the step S4 is usually performed, and in the step S4, metal ions or metal impurities outside the holes in the single crystal silicon wafer are usually cleaned. The second demetallization step in step S7 is to clean metal ions and metal impurities in the nano holes after hole expansion.
In the second demetallization process, the bubbling can generate vibration, metal ions or metal impurities are loosened from the surfaces in the holes of the monocrystalline silicon piece in a physical mode, and gaps are generated between the metal ions or the metal impurities in the holes and the surface of the monocrystalline silicon piece so as to remove the metal ions or the metal impurities; meanwhile, the water containing ozone and the metal ions or metal impurities in the holes are subjected to chemical reaction, for example, the metal ions or metal impurities in the holes are ionized and oxidized by the water containing ozone, the ozone is decomposed into oxygen, so that the adhesion or adsorption of the metal ions or metal impurities and the surface of the monocrystalline silicon piece is influenced, the metal ions or metal impurities are dissolved in the water containing ozone, and the physical vibration can also influence the adsorption between the metal ions or metal impurities and the monocrystalline silicon piece, for example, the ozone is promoted to be dissolved in the water, the water containing ozone and the metal ions or metal impurities are catalyzed to perform chemical reaction, meanwhile, the bubbles and the generated oxygen form bubbles, and the metal ions or metal impurities are extruded out of the nano holes, so that the metal ions or metal impurities in the holes are discharged through the liquid-phase water containing ozone, the metal ions or the metal impurities can not be remained in the holes basically, so that the recombination caused by the metal ions or the metal impurities is obviously reduced, and the power generation efficiency is improved. Meanwhile, in the metal ion-assisted texturing process, the concentration of metal ions is low, so that the metal ions or metal impurities in the holes are low, and the metal ions or metal impurities in the holes are easy to remove.
It should be noted that, between the step S6 and the step S7, at least one cleaning of the monocrystalline silicon wafer with deionized water may be performed to remove the impurities introduced in the step S6.
Optionally, in the second demetallization, water containing ozone is bubbled through nitrogen; and/or ultrasonically bubbling water containing ozone to promote the ozone to be dissolved in the water and loosen metal ions or metal impurities from the surface of the monocrystalline silicon piece in the holes, and generating gaps between the metal ions or the metal impurities in the holes and the surface of the monocrystalline silicon piece to remove the metal ions. Meanwhile, the nitrogen bubbling can also inhibit the self-decomposition of ozone in pure water, prevent the degradation of the oxidizing power of ozone water and promote the metal removal effect.
Optionally, during the second demetallization, hydrogen peroxide may be added to the water containing ozone to increase the oxidizing power, promote the ionization and oxidation of the metal ions or metal impurities in the holes, and further clean the metal ions or metal impurities in the holes.
Optionally, after the step S7, the method may further include performing a third acid washing on the single crystal silicon wafer with a mixed solution of hydrofluoric acid and hydrochloric acid, where in the third acid washing solution, the mass concentrations of HF and HCl are both 2 to 8%, the acid washing temperature is normal temperature, and the acid washing time is 60 to 240S. And in the third acid washing process, impurities and the like on the surface of the monocrystalline silicon wafer are cleaned.
Optionally, after the third acid washing step, the method further comprises a drying treatment of the monocrystalline silicon wafer. The drying temperature can be about room temperature to 90 ℃, the drying can be carried out by hot air, and the gas medium can be hot nitrogen, hot inert gas or clean air and the like.
Optionally, the method may further comprise a step of pre-dehydration after the third pickling step and before the drying step. For example, the pre-dehydration is performed by using hot deionized water with the temperature controlled at about 50-70 ℃ to reduce the time required for drying.
The texturing method also reduces the process steps and improves the production efficiency.
The embodiment of the invention also provides a monocrystalline silicon piece, wherein at least one side surface of the monocrystalline silicon piece is a textured surface. The suede has a pyramid shape, and nano holes are distributed on the side surface of the pyramid. The single crystal silicon wafer can be referred to the above-mentioned FIGS. 2 to 3, and the advantageous effects can be referred to the above-mentioned descriptions. The chroma value L of the texture surface is 10-70, namely the brightness value of the texture surface of the monocrystalline silicon piece provided by the embodiment of the invention is small, so that the monocrystalline silicon piece is uniformly black from all angles.
The colorimetric value L of the textured surface is similar to the resistivity of the silicon wafer and refers to the average value of the whole monocrystalline silicon wafer, but not the colorimetric value of a single point. In actual testing, a plurality of points (for example, five points) may be selected and an average value thereof may be taken as the chromaticity value L of the textured surface.
Optionally, the size of the pyramid is 1-5 μm, the diameter of the nano-holes is 40-130nm, the depth of the nano-holes is 30-120nm, the size of the nano-holes is proper, the band gap of the energy band is wide, absorption of infrared light is enlarged, the light trapping effect is increased, and the short wave reflectivity is reduced. Meanwhile, in the embodiment of the invention, as the size of the nano-holes is proper and uniform, the formed monocrystalline silicon solar cell has a uniform black invisible effect from all angles, has a prominent visual effect, reduces the reflection of the solar cell to light, further improves the average photoelectric conversion efficiency, and has a wider application prospect.
Optionally, the cross section of the nano-hole is square. And the cross-section of the nanometer hole that forms among the prior art is the arc, and for the cross-section of nanometer hole among the prior art is the arc, the cross-section of nanometer hole is square in this application, and square nanometer hole is to the reflection of light less strong, can promote the absorbed quantity of light. More preferably, the cross-section of the nano-holes appears rectangular.
Optionally, the color value L of the texture surface of the monocrystalline silicon piece is 20-60, and the value L can be 30, 35, 40, 45, 50, 55 and the like. More preferably, the value of L is < 40. The texture of the monocrystalline silicon wafer provided by the embodiment of the invention has small brightness value, so that the monocrystalline silicon wafer is uniformly black from all angles, has a prominent visual effect, and the formed solar cell has reduced light reflection, thereby improving the average photoelectric conversion efficiency.
The method of obtaining the single crystal silicon wafer is not particularly limited, and for example, the single crystal silicon wafer can be produced by any of the above-described texturing methods.
The embodiment of the invention also provides a monocrystalline silicon solar cell, which comprises a monocrystalline silicon wafer prepared by any one of the above texturing methods, that is, the monocrystalline silicon wafer prepared by any one of the above texturing methods is used as the monocrystalline silicon wafer of the monocrystalline silicon solar cell, and with regard to the monocrystalline silicon wafer in the monocrystalline silicon solar cell, reference may be made to the relevant contents of the texturing methods, and the same or similar beneficial effects can be achieved, so that, in order to avoid repetition, the description is omitted here.
Optionally, the monocrystalline silicon solar cell further comprises a passivation antireflection film layer located on the light-facing surface of the monocrystalline silicon wafer, and the passivation antireflection film layer mainly has the effects of passivating the monocrystalline silicon wafer and reducing reflection of the light-facing surface of the monocrystalline silicon wafer. Passivation antireflection rete is including silicon nitride layer and the silicon oxide layer of range upon range of setting, above-mentioned monocrystalline silicon piece is kept away from to this silicon oxide layer, that is to say, the silicon nitride layer is closer to monocrystalline silicon piece, the refractive index of the silicon nitride layer that is closer to monocrystalline silicon piece and the silicon oxide layer of keeping away from monocrystalline silicon piece in the above-mentioned passivation antireflection rete matches each other, outer silicon oxide layer has lower refractive index for the silicon nitride layer of inlayer, the reflection of incident ray has been showing and has been reduced, and can realize good passivation effect to the nanometer hole, promote solar cell's generating efficiency, and it is more pleasing to the eye. The passivated antireflection film layer in the embodiment of the invention enables the reflectivity of the single crystal solar cell in the wavelength range of 350nm-1050nm to be less than 4%.
Optionally, the thickness of the passivated antireflection film layer is 50-200nm, and the thickness is the size of the passivated antireflection film layer in the stacking direction of the silicon nitride layer and the silicon oxide layer. The passivation antireflection film layer with the thickness has better passivation effect and antireflection effect.
Optionally, the thickness of the silicon nitride layer is 50-70nm, and the refractive index of the silicon nitride layer is 1.9-2.4, so that the thickness and the refractive index of the silicon nitride layer are more matched with those of the silicon oxide layer, and the passivation effect and the antireflection effect are further improved. The silicon nitride layer can be deposited by means of PECVD, and H in the silicon nitride layer effectively passivates defects on the surface of the single crystal silicon.
Optionally, the silicon nitride layer is one or more layers. In the case of a multilayer structure of silicon nitride layers, the refractive index of each layer of silicon nitride decreases in order from the direction close to the single crystal silicon wafer to the direction away from the single crystal silicon wafer, that is, the refractive index of the silicon nitride layer which is further on the outside is also smaller, and the reflection of incident light is significantly reduced.
Optionally, the thickness of the silicon oxide layer is less than or equal to 50nm, the refractive index of the silicon oxide layer is less than 1.8, and the reflection of incident light is obviously reduced by the outer silicon oxide layer with a lower refractive index, so that the monocrystalline silicon solar cell has a more attractive visual effect, the silicon nitride layer is more matched with the silicon oxide layer in thickness and refractive index, and the passivation effect and the antireflection effect are further improved.
The invention is further illustrated by the following specific examples.
Example 1
The texturing method comprises steps SA1-SA 17:
and step SA1, performing alkali texturing on the monocrystalline silicon wafer, wherein the solution for alkali texturing is a mixed solution of NaOH, additive isopropanol and deionized water, the mass concentration of NaOH in the solution for alkali texturing is 2.5%, the temperature is controlled to be 82 ℃, and the reaction time is 8 min. Detection shows that a pyramid texture with the reflectivity of 10% is formed, and the average size of the pyramid height is 3 mu m.
And step SA2, washing the monocrystalline silicon wafer twice by using deionized water, and washing off alkali texturing solution, organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SA3, using HNO3Subjecting the solution to a first acid washing in which HNO is present3The mass concentration of (A) is 5%, the temperature is controlled to be normal temperature, and the pickling time is 200 s.
Step SA4, deionized water is adopted to wash the monocrystalline silicon piece twice to remove HNO on the surface of the monocrystalline silicon piece3Solutions and organic impurities, etc.
Step SA5, performing metal treatment on the monocrystalline silicon wafer subjected to primary acid cleaning by using a texturing solutionAnd (4) ion-assisted texturing, and manufacturing nano holes on the pyramid texture. The texturing solution is HF and H2O2And a mixed solution containing silver ions, wherein the mass concentration of HF in the texturing solution is 12%, and H is2O2The mass concentration of (A) is 1.5%, the silver ion concentration is 0.0008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s. And step SA6, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing the texturing solution, the organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SA7, performing first demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing, wherein the solution of the first demetallization treatment is NH4OH、H2O2And a mixed solution of deionized water, wherein, in the solution of the first demetallization treatment, NH is added4OH content 3% by mass, H2O2The mass concentration of (2%) is controlled at normal temperature, and the reaction time is 200 s.
And step SA8, washing the monocrystalline silicon wafer twice by using deionized water, and washing off the mixed solution, the organic impurities and the like on the surface of the monocrystalline silicon wafer.
And step SA9, performing secondary acid washing on the mixed solution on the surface of the monocrystalline silicon wafer by adopting a mixed solution of HF and HCl, wherein the mass concentration of HF and HCl in the secondary acid washing solution is 5%, the temperature is controlled to be normal temperature, and the reaction time is 200 s.
And step SA10, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing off HF and HCl mixed solution, organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SA11, using H2O2、HF、NH4F, modifying the nano-pore acid by using a modifying solution, wherein in the modifying solution, H2O2Has a mass concentration of 2.5%, HF has a mass concentration of 0.3%, and NH4The mass concentration of F was 1.5%, and the temperature was controlled to 35 ℃. The modification liquid expands the formed nano holes to obtain NH4F is used as a buffer agent to ensure that the modification liquid keeps stable and controllable etching rate at each position, and the reaction time is 300 s. Step SA12, deionized water is adopted to wash the monocrystalline silicon wafer twice to wash away the monocrystalline siliconA finishing liquid and organic impurities on the surface of the sheet.
And step SA13, bubbling ozone-containing water through nitrogen, and performing secondary demetallization treatment on the reamed monocrystalline silicon wafer in a mode of bubbling ozone-containing water to remove metal ions or metal impurities and organic matters in the nano holes.
And step SA14, performing third acid washing on the monocrystalline silicon wafer by adopting a mixed solution of HF and HCl, wherein the mass concentration of HF and HCl in the third acid washing solution is 5%, the temperature is controlled to be normal temperature, and the reaction time is 200 s.
And step SA15, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing off HF and HCl mixed solution, organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SA16, pre-dewatering with hot deionized water at 50-70 deg.c for 2 min.
Step SA17, drying the monocrystalline silicon wafer.
Example 2
The texturing method comprises the steps of SB1-SB 17:
step SB1, step SB2, step SB3, and step SB4 are respectively the same as steps SA1, step SA2, step SA3, and step SA4, and reference may be made to the corresponding descriptions of step SA1, step SA2, step SA3, and step SA4, and therefore, in order to avoid redundancy, the description thereof is omitted here.
And step SB5, performing metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution, and manufacturing nano holes on the pyramid textured surface. The texturing solution is HF and H2O2And a mixed solution containing silver ions, wherein the mass concentration of HF in the texturing solution is 5%, and H is2O2The mass concentration of (A) is 0.5%, the silver ion concentration is 0.0008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s.
Step SB6, step SB7, step SB8, step SB9, and step SB10 are respectively the same as those of step SA6, step SA7, step SA8, step SA9, and step SA10, and reference may be made to the corresponding descriptions of step SA6, step SA7, step SA8, step SA9, and step SA10, and therefore, in order to avoid redundancy, they are not described again.
Step SB11, using H2O2、HF、NH4F, modifying the nano-pore acid by using a modifying solution, wherein in the modifying solution, H2O29% by mass, 1.4% by mass of HF, and NH4The mass concentration of F was 7% and the temperature was controlled at 35 ℃. The modification liquid expands the formed nano holes to obtain NH4F is used as a buffer agent to ensure that the modification liquid keeps stable and controllable etching rate at each position, and the reaction time is 300 s.
Step SB12, step SB13, step SB14, step SB15, step SB16, and step SB17 are respectively the same as those of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and reference may be made to the corresponding descriptions of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and thus, in order to avoid redundancy, they are not described again.
Example 3
The texturing method comprises the steps SC1-SC 17:
step SC1, step SC2, step SC3, and step SC4 are respectively the same as steps SA1, step SA2, step SA3, and step SA4, and reference may be made to the corresponding descriptions of step SA1, step SA2, step SA3, and step SA4, so that details are not repeated here to avoid redundancy.
And step SC5, metal ion-assisted texturing is carried out on the monocrystalline silicon wafer after the primary acid washing by using a texturing solution, and nano holes are manufactured on the pyramid textured surface. The texturing solution is HF and H2O2And a mixed solution containing silver ions, wherein the mass concentration of HF in the texturing solution is 10%, and H is2O2The mass concentration of (A) is 1.5%, the silver ion concentration is 0.0008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s.
Step SC6, step SC7, step SC8, step SC9, and step SC10 are respectively the same as those of step SA6, step SA7, step SA8, step SA9, and step SA10, and reference may be made to the corresponding descriptions of step SA6, step SA7, step SA8, step SA9, and step SA10, so that details are not repeated here to avoid redundancy.
Step SC11, using H2O2、HF、NH4F, modifying the nano-pore acid by using a modifying solution, wherein in the modifying solution, H2O2Mass concentration of (3) is 7%, mass concentration of HF is 1%, NH4The mass concentration of F is 5%, and the temperature is controlled to 35 ℃. The modification liquid expands the formed nano holes to obtain NH4F is used as a buffer agent to ensure that the modification liquid keeps stable and controllable etching rate at each position, and the reaction time is 300 s.
Step SC12, step SC13, step SC14, step SC15, step SC16, and step SC17 are respectively the same as those of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and reference may be made to the corresponding descriptions of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and thus, in order to avoid redundancy, they are not described herein again.
Example 4
The texturing method comprises the steps of SD1-SD 17:
step SD1, step SD2, step SD3, and step SD4 are respectively the same as those of step SA1, step SA2, step SA3, and step SA4, and reference may be made to the corresponding descriptions of step SA1, step SA2, step SA3, and step SA4, and therefore, in order to avoid redundancy, the description thereof is omitted.
And step SD5, performing metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution, and manufacturing nano holes on the pyramid textured surface. The texturing solution is HF and H2O2And a mixed solution containing silver ions, wherein the mass concentration of HF in the texturing solution is 10%, and H is2O2The mass concentration of (A) is 1.5%, the silver ion concentration is 0.0008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s.
Step SD6, step SD7, step SD8, step SD9, and step SD10 are respectively the same as those of step SA6, step SA7, step SA8, step SA9, and step SA10, and reference may be made to the corresponding descriptions of step SA6, step SA7, step SA8, step SA9, and step SA10, so that details are not repeated here to avoid redundancy.
Step SD11, using H2O2、HF、NH4F, modifying the nano-pore acid by using a modifying solution, wherein in the modifying solution, H2O2Has a mass concentration of 2.5%, HF has a mass concentration of 0.3%, and NH4The mass concentration of F was 1.5%, and the temperature was controlled to 35 ℃. The modification liquid expands the formed nano holes to obtain NH4F is used as a buffer agent to ensure that the modification liquid keeps stable and controllable etching rate at each position, and the reaction time is 300 s.
Step SD12, step SD13, step SD14, step SD15, step SD16, and step SD17 are respectively the same as those of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and reference may be made to the corresponding descriptions of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and thus, in order to avoid redundancy, they are not described again.
Example 5
The texturing method comprises the steps of SF1-SF 17:
step SF1, step SF2, step SF3, and step SF4 are respectively the same as step SA1, step SA2, step SA3, and step SA4, and reference may be made to the corresponding descriptions of step SA1, step SA2, step SA3, and step SA4, so that details are not repeated here to avoid redundancy.
And SF5, performing metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution, and manufacturing nano holes on the pyramid textured surface. The texturing solution is HF and H2O2And a mixed solution containing silver ions, wherein the mass concentration of HF in the texturing solution is 12%, and H is2O2The mass concentration of (A) is 1.5%, the silver ion concentration is 0.0008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s.
Step SF6, step SF7, step SF8, step SF9, and step SF10 are respectively the same as steps SA6, step SA7, step SA8, step SA9, and step SA10, and reference may be made to the corresponding descriptions of steps SA6, step SA7, step SA8, step SA9, and step SA10, so that details are not repeated here to avoid redundancy.
Step SF11, using H2O2、HF、NH4F, modifying the nano-pore acid by using a modifying solution, wherein in the modifying solution, H2O2The mass concentration of (3) is 5%, the mass concentration of HF is 0.6%, and NH is added4The mass concentration of F was 3% and the temperature was controlled at 35 ℃. The modification liquid expands the formed nano holes to obtain NH4F is used as a buffer agent to ensure that the modification liquid keeps stable and controllable etching rate at each position, and the reaction time is 300 s.
Step SF12, step SF13, step SF14, step SF15, step SF16, and step SF17 are respectively the same as those of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and reference may be made to the corresponding descriptions of step SA12, step SA13, step SA14, step SA15, step SA16, and step SA17, and thus, in order to avoid redundancy, they are not described herein again.
Comparative example
The texturing method comprises steps SE1-SE 10:
and step SE1, performing alkali texturing on the monocrystalline silicon wafer, wherein the solution for alkali texturing is a mixed solution of NaOH, additive isopropanol and deionized water, the mass concentration of NaOH in the solution for alkali texturing is 2.5%, the temperature is controlled to be 82 ℃, and the reaction time is 8 min. Detection shows that a pyramid texture with the reflectivity of 10% is formed, and the average size of the pyramid height is 3 mu m.
And step SE2, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing off alkali texturing solution, organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SE3, Using HNO3Subjecting the solution to a first acid washing in which HNO is present3The mass concentration of (A) is 5%, the temperature is controlled to be normal temperature, and the pickling time is 200 s.
Step SE4, adopting deionized water to carry out twice cleaning on the monocrystalline silicon piece, and washing off HNO on the surface of the monocrystalline silicon piece3Solutions and organic impurities, etc.
Step SE5, texturing is adopted for the monocrystalline silicon piece after the primary acid washingAnd (4) carrying out metal ion assisted texturing on the solution, and manufacturing nano holes on the pyramid textured surface. The texturing solution is HF and H2O2And a mixed solution containing metal ions, wherein the mass concentration of HF in the texturing solution is 12%, and H is2O2The mass concentration of the catalyst is 1.5 percent, the concentration of metal ions is 0.008mol/L, the temperature is controlled to be 33 ℃, and the reaction time is 300 s.
And step SE6, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing the texturing solution, the organic impurities and the like on the surface of the monocrystalline silicon wafer.
Step SE7, performing first demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing, wherein the solution of the first demetallization treatment is NH4OH、H2O2And a mixed solution of deionized water, wherein, in the solution of the first demetallization treatment, NH is added4OH content 3% by mass, H2O2The mass concentration of (2%) is controlled at normal temperature, and the reaction time is 200 s.
And step SE8, cleaning the monocrystalline silicon wafer twice by using deionized water, and washing off the mixed solution, the organic impurities and the like on the surface of the monocrystalline silicon wafer.
And step SE9, pre-dehydrating for 2min by using hot deionized water with the temperature controlled at about 50-70 ℃.
And step SE10, drying the monocrystalline silicon wafer.
And (3) performance testing:
the single crystal silicon wafers of example 1, example 2, example 3, example 4 and example 5 were each measured by a BYK mac i multi-angle colorimeter. The projection of incident light of the BYK mac i multi-angle color measuring instrument on the horizontal plane where the monocrystalline silicon piece is located is measured under the condition that an angle of 45 degrees is formed between the projection of the incident light and the edge of the monocrystalline silicon piece, and the incident light can be enabled to be incident on one inclined plane of the pyramid suede.
The test parameters are D65/10 degrees and D65 represents a standard light source, the L value of each single point of the single crystal silicon wafer corresponding to each embodiment is tested by selecting five points, and the average value of the L values of the five points corresponding to the single crystal silicon wafer in each embodiment is taken as the L value of the embodiment. The test results were as follows:
at 110 °, example 1 corresponds to an L value of 15, example 2 corresponds to an L value of 68, example 3 corresponds to an L value of 39, example 4 corresponds to an L value of 18, and example 5 corresponds to an L value of 23. A comparative monocrystalline silicon wafer was tested under the same test conditions, the comparative example having an L value of 85. Wherein 110 ° is the observation angle of the BYK mac i multi-angle colorimeter, and the L value is a colorimetric value.
The test results show that the degree of decrease in the chromaticity values of the silicon wafers in the examples is large, and the single crystal silicon wafers in the examples show uniform black color from various angles, which further shows that the sizes of the nano holes are appropriate and uniform.
Using the monocrystalline silicon wafers prepared in example 1, example 2, example 3, example 4, example 5 and comparative example, respectively, M6 size monocrystalline PERC solar cells having the same structure were prepared under the same conditions. The test conditions were: spectral distribution AM1.5G, illumination intensity 1000W/m2The solar simulator of (1) measures photoelectric conversion efficiency. All tests were carried out in an atmospheric environment (25 ℃, 45 RH%).
The test results were as follows:
the average photoelectric conversion efficiency of the solar cell obtained from 9000 sheets of example 1 was 20.94%, the average photoelectric conversion efficiency of the solar cell obtained from 9000 sheets of example 2 was 20.81%, the average photoelectric conversion efficiency of the solar cell obtained from 9000 sheets of example 3 was 20.87%, the average photoelectric conversion efficiency of the solar cell obtained from 9000 sheets of example 4 was 20.91%, and the average photoelectric conversion efficiency of the solar cell obtained from 9000 sheets of example 5 was 20.89%; the average photoelectric conversion efficiency of 9000 comparative examples obtained solar cells was 20.79%. In the embodiment of the invention, the suede structure is more uniform, the suede structure has less effect on light reflection, and the utilization rate of light is higher, so that the short-circuit current is improved; meanwhile, metal ions or metal impurities in the nano holes are cleaned thoroughly, and the nano holes are less compounded, so that the average photoelectric conversion efficiency of the solar cell is improved.
As can be seen from the above, the solar cells according to examples 1, 2, 3, 4, and 5 have higher photoelectric conversion efficiency than the solar cells according to the comparative examples.
It can be seen from the above comparison that, in the embodiments 1, 2, 3, 4, and 5, the metal ions in the nano holes are thoroughly cleaned, so that the recombination caused by the metal ions is significantly reduced, and meanwhile, the obtained nano holes have appropriate sizes, so that the reflectivity of the surface of the monocrystalline silicon wafer can be effectively reduced, and the power generation efficiency is improved.
It should be noted that for simplicity of description, the method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the illustrated order of acts, as some steps may occur in other orders or concurrently depending on the embodiment of the invention. Furthermore, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative rather than restrictive, and it will be apparent to those skilled in the art that many more modifications and variations can be made without departing from the spirit of the invention and the scope of the appended claims.

Claims (19)

1. A method of texturing comprising the steps of:
carrying out alkali texturing on the monocrystalline silicon wafer to form a pyramid textured surface;
carrying out primary acid washing on the monocrystalline silicon wafer subjected to alkali texturing;
carrying out metal ion-assisted texturing on the monocrystalline silicon wafer subjected to the primary acid washing by using a texturing solution to form nano holes on the pyramid textured surface; the content of metal ions in the texturing solution is 0.0001-0.001 mol/L;
performing primary demetallization treatment on the monocrystalline silicon wafer subjected to metal ion assisted texturing;
carrying out acid washing on the monocrystalline silicon wafer subjected to the first demetallization for the second time;
modifying the monocrystalline silicon wafer after the second pickling by using a modifying solution to expand the nanometer holes;
and (3) performing secondary demetallization on the reamed monocrystalline silicon wafer by adopting a water bubbling mode containing ozone.
2. The texturing method according to claim 1, wherein the modifying solution is a mixed solution of hydrogen peroxide, hydrofluoric acid and ammonium fluoride; wherein, in the modifying liquid, H2O2The mass concentration of (A) is 2-10%, the mass concentration of HF is 0.3-2%, and NH4The mass concentration of F is 1.5-10%.
3. The texturing method according to claim 1, wherein in the second demetallization, water containing ozone is bubbled through nitrogen gas; and/or, ultrasonically bubbling the water containing ozone.
4. The texturing method according to claim 1, wherein the metal ions are selected from at least one of silver ions, copper ions, nickel ions, platinum ions, palladium ions or gold ions.
5. A texturing method according to claim 1 or 3, characterized in that in the second demetallization, the ozone-containing water contains hydrogen peroxide.
6. The texturing method according to claim 2, wherein in the modification, the modification temperature is 8 to 40 ℃, the modification time is 90 to 480 s; the diameter of the modified nanometer hole is 40-130nm, and the depth is 30-120 nm.
7. A texturing method according to any one of claims 1 to 4, characterized in thatThe texturing solution also comprises hydrofluoric acid and hydrogen peroxide; wherein, in the texturing solution, the mass concentration of HF is 5-15%, and H2O2The mass concentration of the nano-pores is 0.2-2%, the texture-making temperature is 30-35 ℃, the reaction time is 90-480s, the diameter of the nano-pores obtained by metal ion assisted texture-making is 30-120nm, and the depth is 20-100 nm.
8. A texturing method according to any one of claims 1 to 4, wherein the first demetallization solution comprises ammonium hydroxide, hydrogen peroxide and deionized water, wherein in the first demetallization solution NH is present4OH mass concentration of 1-5%, H2O2The mass concentration of the catalyst is 1-5%, the demetallization temperature is normal temperature, and the reaction time is 90-450 s.
9. The texturing method according to any one of claims 1 to 4, wherein the solution in the alkaline texturing step comprises sodium hydroxide, an additive and deionized water, wherein the mass concentration of NaOH in the alkaline texturing solution is 1 to 5%, the texturing temperature is 80 to 90 ℃, the reaction time is 5 to 10min, the reflectivity of the pyramid textured surface is 9 to 15%, and the size of the pyramid textured surface is 1 to 5 μm.
10. The method according to any one of claims 1 to 4, wherein in the first pickling step, pickling is performed with a nitric acid solution, and HNO is added to the first pickling solution3The mass concentration of the acid is 1-10%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s;
in the second acid washing step, mixed solution of hydrofluoric acid and hydrochloric acid is adopted for acid washing, wherein in the second acid washing solution, the mass concentration of HF and HCl is 2-8%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s.
11. The texturing method according to any one of claims 1 to 4, wherein after the second demetallization step, the method further comprises performing a third acid washing on the monocrystalline silicon wafer by using a mixed solution of hydrofluoric acid and hydrochloric acid, wherein in the third acid washing solution, the mass concentration of HF and HCl is 2-8%, the acid washing temperature is normal temperature, and the acid washing time is 60-240 s;
the method further comprises a drying treatment of the monocrystalline silicon wafer after the third pickling step.
12. The texturing method according to any one of claims 1 to 4, wherein after each step, the single-crystal silicon wafer is subjected to at least one cleaning with deionized water.
13. A monocrystalline silicon piece is characterized in that at least one side surface of the monocrystalline silicon piece is a textured surface; the texture surface has a pyramid shape, and nano holes are distributed on the surface of the pyramid; the chroma value L of the suede is 10-70.
14. The single crystal silicon wafer according to claim 13, wherein the size of the pyramid is 1 to 5 μm; the diameter of the nanometer hole is 40-130nm, and the depth is 30-120 nm;
the cross section of the nanometer hole is square.
15. The single-crystal silicon wafer of claim 13, wherein the textured surface has a colorimetric value L of 20 to 60.
16. A monocrystalline silicon solar cell, characterized by comprising a monocrystalline silicon wafer produced by the texturing method according to any one of claims 1 to 12.
17. The monocrystalline silicon solar cell of claim 16, further comprising a passivating antireflection film layer on a light-facing side of the monocrystalline silicon wafer; the passivated antireflection film layer comprises a silicon nitride layer and a silicon oxide layer which are arranged in a stacked mode; the silicon oxide layer is far away from the monocrystalline silicon piece.
18. The monocrystalline silicon solar cell of claim 17, wherein the passivated antireflective film layer has a thickness of 50-200 nm;
the thickness of the silicon nitride layer is 50-70 nm; the refractive index of the silicon nitride layer is 1.9-2.4;
the thickness of the silicon oxide layer is less than or equal to 50 nm; the refractive index of the silicon oxide layer is less than 1.8.
19. The monocrystalline silicon solar cell according to claim 17 or 18, characterized in that the silicon nitride layer is of one or more layer structures;
when the silicon nitride layer has a multilayer structure, the refractive index of each layer of silicon nitride decreases in order from the direction close to the single crystal silicon wafer to the direction away from the single crystal silicon wafer.
CN202011629109.3A 2020-12-30 2020-12-30 Texturing method, monocrystalline silicon wafer and monocrystalline silicon solar cell Pending CN112652671A (en)

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