TEXTURED STRUCTURE OF CRYSTALLINE SILICON SOLAR CELL AND PREPARATION METHOD THEREOF

Abstract

A textured structure of a crystalline silicon solar cell that is mainly constructed by a plurality of micro-structures similar to inverted pyramids; the lower part of the micro-structure similar to the inverted pyramid is an inverted pyramidal structure, and the upper part thereof is an inverted circular truncated conical structure; and the top of the micro-structure similar to the inverted pyramid is selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves. Experiments prove that the conversion efficiency of a cell piece may be improved by 0.25-0.4%, thereby obtaining unexpected effects.

Claims

1. A textured structure of a crystalline silicon solar cell, wherein the textured structure is mainly constructed by a plurality of micro-structures similar to inverted pyramids; the lower part of the micro-structure similar to the inverted pyramid is an inverted pyramidal structure, and the upper part thereof is an inverted circular truncated conical structure; and the top of the micro-structure similar to the inverted pyramid is selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves.

2. The textured structure of a crystalline silicon solar cell according to claim 1, wherein the size of the micro-structure similar to the inverted pyramid is 100-900 nm.

3. The textured structure of a crystalline silicon solar cell according to claim 1, wherein the textured structure further comprises a plurality of pyramid micro-structures.

4. A preparation method of a textured structure of a crystalline silicon solar cell, comprising the following steps: (1) immersing a silicon wafer in a solution containing metal ions, so that a layer of metal nano-particles is coated on the surface of the silicon wafer; the concentration of the metal ions in the solution being less than or equal to 1E.sup.−3 mol/L or the concentration of the metal ions in the solution being greater than 1E.sup.−3 mol/L while the concentration of HF being less than or equal to 1E.sup.−2 mol/L; (2) corroding the surface of the silicon wafer by using a first chemical corrosive liquid, so as to form nanowires or porous silicon structures, the temperature being 25-90° C., and the time being 2-10 min; the first chemical corrosive liquid being a mixed solution of HF and an oxidant, wherein the concentration of the HF is 1-15 mol/L, and the concentration of the oxidant is 0.05-0.5 mol/L; (3) placing the silicon wafer in a second chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into nano-deep hole structures; the second chemical corrosive liquid being a mixed solution of an oxidant and the HF acid, the concentrations of the HF and the oxidant being respectively 0.05-0.5 mol/L and 1-10 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-45° C.; (4) placing the silicon wafer in a third chemical corrosive liquid to perform corrective corrosion, so that the nano-deep hole structures are formed into micro-structures similar to inverted pyramids; the lower part of the micro-structure similar to the inverted pyramid being an inverted pyramidal structure, and the upper part thereof being an inverted circular truncated conical structure; the top of the micro-structure similar to the inverted pyramid being selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves; the third chemical corrosive liquid being an alkali liquor; the concentration of the alkali liquor being 0.001-0.1 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-85° C.

5. The preparation method according to claim 4, wherein the solution containing metal ions in the step (1) further comprises HF.

6. A preparation method of a textured structure of a crystalline silicon solar cell, comprising the following steps: (1) placing a silicon wafer into the hydrofluoric acid solution containing an oxidant and a metal salt, so as to form nanowires or porous silicon structures, the temperature being 25-90° C., and the time being 2-10 min; the concentration of the metal ions in the solution being less than or equal to 1E.sup.−3 mol/L or the concentration of the metal ions in the solution being greater than 1E.sup.−3 mol/L while the concentration of HF being less than or equal to 1E.sup.−2 mol/L; (2) placing the silicon wafer in a first chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into nano-deep hole structures; the first chemical corrosive liquid being a mixed solution of an oxidant and the HF acid, the concentrations of the HF and the oxidant being respectively 0.05-0.5 mol/L and 1-10 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-45° C.; (3) placing the silicon wafer in a second chemical corrosive liquid to perform corrective corrosion, so that the nano-deep hole structures are formed into micro-structures similar to inverted pyramids; the lower part of the micro-structure similar to the inverted pyramid being an inverted pyramidal structure, and the upper part thereof being an inverted circular truncated conical structure; the top of the micro-structure similar to the inverted pyramid being selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves; the second chemical corrosive liquid being an alkali liquor; the concentration of the alkali liquor being 0.001-0.1 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-85° C.

7. A textured structure of a crystalline silicon solar cell, wherein the textured structure is mainly constructed by a plurality of pyramid micro-structures; and the size of the pyramid is 100-500 nm.

8. The textured structure of a crystalline silicon solar cell according to claim 7, wherein the textured structure further comprises a plurality of micro-structures similar to inverted pyramids; the lower part of the micro-structure similar to the inverted pyramid is an inverted pyramidal structure, and the upper part thereof is an inverted circular truncated conical structure; and the top of the micro-structure similar to the inverted pyramid is selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves.

9. A preparation method of a textured structure of a crystalline silicon solar cell, comprising the following steps: (1) immersing a silicon wafer in a solution containing metal ions, so that a layer of metal nano-particles is coated on the surface of the silicon wafer; the concentration of the metal ions in the solution being greater than 1E.sup.−3 mol/L, and the concentration of HF being greater than 1E.sup.−2 mol/L; (2) corroding the surface of the silicon wafer by using a first chemical corrosive liquid, so as to form nanowires or porous silicon structures; the temperature being 25-90° C., and the time being 2-10 min; the first chemical corrosive liquid being a mixed solution of HF and an oxidant, wherein the concentration of the HF is 1-15 mol/L, and the concentration of the oxidant is 0.05-0.5 mol/L; (3) placing the silicon wafer in a second chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into pyramid micro-structures; the second chemical corrosive liquid being an alkali liquor; the concentration of the alkali liquor being 0.001-0.1 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-85° C.

10. The preparation method according to claim 9, wherein the solution containing metal ions in the step (1) further comprises HF.

11. A preparation method of a textured structure of a crystalline silicon solar cell, comprising the following steps: (1) placing a silicon wafer into a hydrofluoric acid solution containing an oxidant and a metal salt, so as to form nanowires or porous silicon structures; the temperature being 25-90° C., and the time being 2-10 min; the concentration of the metal ions in the solution being greater than 1E.sup.−3 mol/L, and the concentration of HF being greater than 1E.sup.−2 mol/L; (2) placing the silicon wafer in a first chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into pyramid micro-structures; the first chemical corrosive liquid being an alkali liquor; the concentration of the alkali liquor being 0.001-0.1 mol/L, the reaction time being 10-1000 seconds, and the reaction temperature being 5-85° C.

12. The preparation method according to claim 4, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

13. The preparation method according to claim 5, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

14. The preparation method according to claim 6, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

15. The preparation method according to claim 9, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

16. The preparation method according to claim 10, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

17. The preparation method according to claim 11, wherein, before or after the correction step, the method further comprises a step of removing the metal ions, in which metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner and a deionized water, wherein the first cleaner is a nitric acid solution with mass percentage of 27-69%, the cleaning time is 60-1200 seconds, and the cleaning temperature is 5-85° C.; the second cleaner is a hydrofluoric acid solution with mass percentage of 1-10%, the cleaning time is 60-600 seconds, and the cleaning temperature is 5-45° C.

Description

DESCRIPTION OF THE DRAWINGS

[0086] FIG. 1 is an SEM scanning diagram of a texture of a polycrystalline silicon wafer according to Embodiment 1 of the present invention;

[0087] FIG. 2 is an SEM scanning diagram of a texture of a polycrystalline silicon wafer according to Embodiment 2 of the present invention;

[0088] FIG. 3 is a schematic diagram of a forming principle of a texture of a polycrystalline silicon wafer according to Embodiment 1 of the present invention; and

[0089] FIG. 4 is a schematic diagram of a forming principle of a texture of a polycrystalline silicon wafer according to Embodiment 2 of the present invention.

DETAILED DESCRIPTION

[0090] The present invention is further described through embodiments.

Embodiment 1

[0091] Referring to FIG. 3, a preparation method of a textured structure of a polycrystalline silicon solar cell includes the following steps:

[0092] (1) cleaning a silicon wafer to remove a damaged surface layer;

[0093] (2) placing the silicon wafer in a chemical corrosive liquid containing metal ions, so as to form nanowires or porous silicon structures on the surface of the silicon wafer, the temperature being 30° C., and the time being 2 min;

[0094] the metal ions being selected from silver ions;

[0095] the chemical corrosive liquid being selected from a mixed solution of HF and H.sub.2O.sub.2;

[0096] where the concentration of the HF is 10 mol/L, and the concentration of the H.sub.2O.sub.2 is 0.4 mol/L;

[0097] (3) placing the silicon wafer in a first chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into nano-deep hole structures;

[0098] the first chemical corrosive liquid being a mixed solution of HNO.sub.3 and HF acid, the concentrations of the HF and the HNO.sub.3 being respectively 0.5 mol/L and 10 mol/L, the reaction time being 20 seconds, and the reaction temperature being the room temperature;

[0099] (4) placing the silicon wafer in a second chemical corrosive liquid to perform corrective corrosion, so that the nano-deep hole structures are formed into nano-sized micro-structures similar to inverted pyramids;

[0100] the lower part of the micro-structure similar to the inverted pyramid being an inverted pyramidal structure, and the upper part thereof being an inverted circular truncated conical structure; the top of the micro-structure similar to the inverted pyramid being selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves;

[0101] the second chemical corrosive liquid being selected from a tetramethylammonium hydroxide solution, the concentration thereof being 0.1 mol/L, the reaction time being 100 seconds, and the reaction temperature being the room temperature;

[0102] (5) cleaning and spin-drying, so as to form the textured structure of the crystalline silicon solar cell.

[0103] The concentration of the metal ions in the step (2) is 5E.sup.−4 mol/L.

[0104] The cleaning in the step (5) specifically includes that:

[0105] metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner, and a deionized water;

[0106] where the first cleaner is a nitric acid solution with mass percentage of 69%, the cleaning time is 1200 seconds, and the cleaning temperature is the room temperature; and

[0107] the second cleaner is a hydrofluoric acid solution with mass percentage of 10%, the cleaning time is 600 seconds, and the cleaning temperature is the room temperature.

[0108] The SEM scanning diagram of the obtained texture of the polycrystalline silicon wafer is shown in FIG. 1, nano-sized micro-structures similar to inverted pyramids in the size of about 400 nm are formed. The lower part of the micro-structure similar to the inverted pyramid is an inverted pyramidal structure, and the upper part thereof is an inverted circular truncated conical structure; the top of the micro-structure similar to the inverted pyramid being selected from one or more of a circle, an oval, or a closed figure enclosed by multiple curves.

Embodiment 2

[0109] Referring to FIG. 4, a preparation method of a textured structure of a polycrystalline silicon solar cell includes the following steps:

[0110] (1) cleaning a silicon wafer to remove a damaged surface layer;

[0111] (2) placing the silicon wafer in a chemical corrosive liquid containing metal ions, so as to form nanowires or porous silicon structures on the surface of the silicon wafer; the temperature being 30° C., and the time being 2 min;

[0112] the metal ions being selected from silver ions;

[0113] the chemical corrosive liquid being selected from a mixed solution of HF and H.sub.2O.sub.2;

[0114] where the concentration of the HF is 10 mol/L, and the concentration of the H.sub.2O.sub.2 is 0.4 mol/L;

[0115] (3) placing the silicon wafer in a first chemical corrosive liquid to perform corrective corrosion, so that the nanowires or porous silicon structures are formed into nano-deep hole structures;

[0116] the first chemical corrosive liquid being a mixed solution of HNO.sub.3 and HF acid, the concentrations of the HF and the HNO.sub.3 being respectively 0.01 mol/L and 10 mol/L, the reaction time being 10 seconds, and the reaction temperature being the room temperature;

[0117] (4) placing the silicon wafer in a second chemical corrosive liquid to perform corrective corrosion, so that the nano-deep hole structures are formed into pyramid micro-structures;

[0118] the second chemical corrosive liquid being selected from a tetramethylammonium hydroxide solution, the concentration thereof being 0.01 mol/L, the reaction time being 60 seconds, and the reaction temperature being 45° C.;

[0119] (5) cleaning and spin-drying, so as to form the textured structure of the crystalline silicon solar cell.

[0120] The concentration of the metal ions in the step (2) is 0.1 mol/L.

[0121] The cleaning in the step (5) specifically includes that:

[0122] metal particles are removed respectively by washing the silicon wafer using a first cleaner, a second cleaner, and a deionized water;

[0123] where the first cleaner is a nitric acid solution with mass percentage of 69%, the cleaning time is 1200 seconds, and the cleaning temperature is 80° C.; and

[0124] the second cleaner is a hydrofluoric acid solution with mass percentage of 10%, the cleaning time is 600 seconds, and the cleaning temperature is 40° C.

[0125] The SEM scanning diagram of the obtained textured of the polycrystalline silicon wafer is shown in FIG. 2, and nano-sized pyramid micro-structures in the size of about 400 nm are formed.

[0126] Comparison 1

[0127] A nano textured structure is prepared according to the method disclosed in the patent application No. WO2014120830(A1) by using raw materials the same as those in the embodiments.

[0128] Comparison results of conversion efficiencies of cell pieces manufactured according to the prior art are shown in the following.

TABLE-US-00001 Uoc (mV) Jsc (mA/cm.sup.2) FF (%) EFF Comparison 1 637.7 36.05 79.30 18.23% Embodiment 1 638.9 36.49 79.90 18.63% Embodiment 2 637.0 36.61 79.25 18.48%

[0129] It can be seen that, compared with the textured structure (comparison) disclosed in the patent application No. WO2014120830(A1), the conversion efficiency of the cell piece of the present invention may be improved by about 0.25-0.4%, thereby achieving unexpected effects.