All-black crystalline silicon solar cell and preparation method therefor, and photovoltaic module

Abstract

Disclosed in the present invention are an all-black crystalline silicon solar cell and a preparation method therefor, and a photovoltaic module. The preparation method comprises the following steps: (1) depositing a film layer on the front face of a silicon wafer by means of a PECVD method so as to obtain a silicon wafer having a coated front face, wherein the film layer is of a laminated structure and comprises an innermost SiN.sub.x layer having a thickness of 20 nm or more; (2) subjecting the resulting silicon wafer having the coated front face to back-face PECVD and laser beam grooving so as to obtain a coarse silicon solar cell; and (3) subjecting the resulting coarse silicon solar cell to silk-screen printing and electron injection to then obtain an all-black crystalline silicon solar cell. In the preparation method provided in the present application, the film layer is deposited on the front face of the silicon wafer by means of the PECVD method, the material and thickness of the innermost SiNx layer are designed, and particularly when the thickness thereof is 20 nm or more, the absorption and reflection effects of incident light on the surface of the cell are influenced, such that the incident light is almost completely absorbed, and only an extremely small amount of the incident light is reflected; therefore, the all-black crystalline silicon solar cell is obtained.

Claims

1. A method for preparing an all-black crystalline silicon solar cell, comprising the following steps: (1) depositing a film layer on a front surface of a silicon wafer by a PECVD method to obtain a front-coated silicon wafer, where the film layer is a layered structure, and the film layer comprises an innermost SiN.sub.x layer with a thickness of 25-50 nm and the innermost SiN.sub.x layer has a refractive index of 2.8-3.4; (2) subjecting the front-coated silicon wafer to back PECVD and laser grooving to obtain a crude silicon solar cell; and (3) subjecting the crude silicon solar cell to screen printing and current injection to obtain the all-black crystalline silicon solar cell, a method of the screen printing comprises: after the grooving, subjecting the crude silicon solar cell to a first printing and drying, a second printing and drying, a third printing and drying, a fourth printing and drying, sintering, and testing linewidths of the cell to complete the screen printing, the fourth printing is performed with a gradient linewidth screen under pressure, and a linewidth of the gradient linewidth screen is reduced in a gradient manner from outside to inside, wherein a difference between the linewidths of the cell tested is less than or equal to 5 m.

2. The method for preparing an all-black crystalline silicon solar cell according to claim 1, wherein the film layer in step (1) comprises the innermost SiN.sub.x layer, an intermediate SiN.sub.x layer, a SiO.sub.xN.sub.y layer and a SiO.sub.x layer which are stacked from inside to outside.

3. The method for preparing an all-black crystalline silicon solar cell according to claim 1, wherein an outermost layer of the film layer in step (1) comprises a SiO.sub.x layer.

4. The method for preparing an all-black crystalline silicon solar cell according to claim 3, wherein the SiO.sub.x layer has a refractive index of 1.45-1.55.

5. The method for preparing an all-black crystalline silicon solar cell according to claim 2, wherein the SiO.sub.x layer has a thickness of more than or equal to 20 nm.

6. The method for preparing an all-black crystalline silicon solar cell according to claim 1, wherein the depositing in step (1) comprises the following steps: (a) vacuuming, then pre-introducing silane and ammonia gas at a constant pressure; (b) depositing the innermost SiN.sub.x layer on the front surface of the silicon wafer; (c) depositing an intermediate SiN.sub.x layer on the innermost SiN.sub.x layer, and depositing a SiO.sub.xN.sub.y layer on the intermediate SiN.sub.x layer; (d) vacuuming, then pre-introducing silane and laughing gas at a constant pressure; and (e) depositing a SiO.sub.x layer on the SiO.sub.xN.sub.y layer.

7. The method for preparing an all-black crystalline silicon solar cell according to claim 6, wherein the constant pressure in step (a) is 200-250 Pa; the pre-introducing in step (a) is performed for 15-30 s; the pre-introducing silane in step (a) has a flow rate of 2200-2500 sccm; the pre-introducing ammonia gas in step (a) has a flow rate of 9000-9300 sccm; the pre-introducing in step (a) is performed at 400-600 C.; the depositing in step (b) is performed for 60-80 s; the depositing in step (b) is performed at 400-600 C.; the depositing in step (b) is performed at 200-250 Pa; silane and ammonia gas are introduced during the depositing in step (b); the silane introduced has a flow rate of 2200-2500 sccm; the ammonia gas introduced has a flow rate of 9000-9300 sccm; the depositing in step (b) is performed at a radio frequency power of 14000-16000 W; the depositing in step (b) is performed at a pulse switching ratio of (3 to 5)/(50 to 70).

8. The method for preparing an all-black crystalline silicon solar cell according to claim 6, wherein the constant pressure in step (d) is 150-200 Pa; the pre-introducing in step (d) is performed for 5-15 s; the pre-introducing silane in step (d) has a flow rate of 600-700 sccm; the pre-introducing laughing gas in step (d) has a flow rate of 10000-12000 sccm; the pre-introducing in step (d) is performed at 400-600 C.

9. The method for preparing an all-black crystalline silicon solar cell according to claim 6, wherein the depositing in step (e) is performed for 150-200 s; the depositing in step (e) is performed at 400-600 C.; the depositing in step (e) is performed at 100-150 Pa; silane and laughing gas are introduced during the depositing in step (e); the silane introduced has a flow rate of 600-700 sccm; the laughing gas introduced has a flow rate of 10000-12000 sccm; the depositing in step (e) is performed at a radio frequency power of 14000-16000 W; the depositing in step (e) is performed at a pulse switching ratio of (1 to 3)/(30 to 50).

10. The method for preparing an all-black crystalline silicon solar cell according to claim 1, wherein the linewidth of the gradient linewidth screen is reduced by at most 1 m but more than 0 m every 5 mm or less but more than 0 mm from an outer edge to inside.

11. The method for preparing an all-black crystalline silicon solar cell according to claim 2, wherein the SiO.sub.x layer has a thickness of 20-40 nm.

12. The method for preparing an all-black crystalline silicon solar cell according to claim 2, wherein the SiO.sub.x layer has a refractive index of 1.45-1.55.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Accompanying drawings are used to provide a further understanding of the technical solutions herein and form part of the specification. The accompanying drawings are used in conjunction with examples of the present application to explain the technical solutions herein, and do not limit the technical solutions herein.

(2) FIG. 1 is a structural schematic diagram of a film layer provided in step (1) of Examples 1, 2, and 3 of the present application.

(3) FIG. 2 is a structural schematic diagram of a gradient linewidth screen provided in Example 1.

(4) Reference list: 1silicon wafer, 2innermost SiN.sub.x layer, 3intermediate SiN.sub.x layer, 4SiO.sub.xN.sub.y layer, and 5SiO.sub.x layer.

DETAILED DESCRIPTION

(5) The technical solutions of the present application are further described below with reference to embodiments and drawings. However, the following examples are only simple examples of the present application, and do not represent or limit the protection scope of the claims of the present application, and the protection scope of the present application is defined by the claims.

Example 1

(6) This example provides a method for preparing an all-black crystalline silicon solar cell, and the method comprises the following steps: (1) a film layer (FIG. 1) was deposited on the front surface of a silicon wafer 1 (Longi silicon wafer with a resistivity of 0.4-1.1, a thickness of 160 m and a size of 166 mm) by a PECVD method, the film layer was a layered structure, and a front-coated silicon wafer was obtained; and the film layer comprised an innermost SiN.sub.x layer 2, an intermediate SiN.sub.x layer 3, a SiO.sub.xN.sub.y layer 4 and a SiO.sub.x layer 5 which were stacked from inside to outside; the innermost SiN.sub.x layer 2 had a thickness of 20 nm and a refractive index of 2.3; the SiO.sub.x layer 5 was the outermost layer, and had a thickness of 20 nm and a refractive index of 1.5; the deposition of the film layer in step (1) comprises the following steps: (a) after vacuuming, silane and ammonia gas were pre-introduced for 20 s at a constant pressure of 230 Pa, where the silane had a flow rate of 2316 sccm, and the ammonia gas had a flow rate of 9276 sccm, and a temperature was 500 C.; (b) an innermost SiN.sub.x layer 2 was deposited on the front surface of the silicon wafer 1, where a deposition period was 70 s, a temperature was 500 C., a constant pressure was 240 Pa, the silane had a flow rate of 2316 sccm, the ammonia gas had a flow rate of 9276 sccm, a radio frequency power was 14500 W, and a pulse switching ratio was 4/60; (c) an intermediate SiN.sub.x layer 3 was deposited on the innermost SiN.sub.x layer 2, and a SiO.sub.xN.sub.y layer 4 was deposited on the intermediate SiN.sub.x layer 3; (d) after vacuuming, silane and laughing gas was pre-introduced for 10 s at a constant pressure of 180 Pa and a temperature of 500 C., where the silane had a flow rate of 686 sccm, and the laughing gas had a flow rate of 10990 sccm; and (e) a SiO.sub.x layer 5 was deposited on the SiO.sub.xN.sub.y layer 4, where a period was 190 s, a temperature was 500 C., a constant pressure was 130 Pa, the silane had a flow rate of 686 sccm, and the laughing gas had a flow rate of 10990 sccm, a radio frequency power was 14500 W, and a pulse switching ratio was 2/38; (2) the obtained front-coated silicon wafer was subjected to back PECVD and laser grooving, and a crude silicon solar cell was obtained; and (3) the obtained crude silicon solar cell was subjected to screen printing and current injection, and then the all-black crystalline silicon solar cell was obtained; a method of the screen printing comprises: after loading and grooving the wafer, the crude silicon solar cell was subjected to a first printing and drying, a second printing and drying, a third printing and drying, and a fourth printing by using a gradient linewidth screen and drying, and sintering, a linewidth of the cell was tested, and then the screen printing was completed; within 15 mm from an edge of the gradient linewidth screen (FIG. 2) to inside, the linewidth was reduced by 1 m every 5 mm, and a linewidth at the starting position was 20 m and 18, 19, and 20 of FIG. 2 represent the linewidths of the marked lines with a unit of m.

Example 2

(7) This example provides a method for preparing an all-black crystalline silicon solar cell, and the method comprises the following steps: (1) a film layer (FIG. 1) was deposited on the front surface of a silicon wafer 1 by a PECVD method, the film layer was a layered structure, and a front-coated silicon wafer was obtained; the film layer comprised an innermost SiN.sub.x layer 2, an intermediate SiN.sub.x layer 3, a SiO.sub.xN.sub.y layer 4 and a SiO.sub.x layer 5 which were stacked from inside to outside; the innermost SiN.sub.x layer 2 had a thickness of 22 nm and a refractive index of 2.5; the SiO.sub.x layer 5 was the outermost layer, and had a thickness of 22 nm and a refractive index of 1.45; the deposition of the film layer in step (1) comprises the following steps: (a) after vacuuming, silane and ammonia gas were pre-introduced for 30 s at a constant pressure of 250 Pa, where the silane had a flow rate of 2200 sccm, and the ammonia gas had a flow rate of 9300 sccm, a temperature was 400 C.; (b) an innermost SiN.sub.x layer 2 was deposited on the front surface of the silicon wafer 1, where a deposition period was 80 s, a temperature was 400 C., a constant pressure was 250 Pa, the silane had a flow rate of 2500 sccm, the ammonia gas had a flow rate of 9300 sccm, a radio frequency power was 16000 W, and a pulse switching ratio was 3/70; (c) an intermediate SiN.sub.x layer 3 was deposited on the innermost SiN.sub.x layer 2, and a SiO.sub.xN.sub.y layer 4 was deposited on the intermediate SiN.sub.x layer 3; (d) after vacuuming, silane and laughing gas was pre-introduced for 15 s at a constant pressure of 200 Pa and a temperature of 400 C., where the silane had a flow rate of 700 sccm, and the laughing gas had a flow rate of 12000 sccm; and (e) a SiO.sub.x layer 5 was deposited on the SiO.sub.xN.sub.y layer 4, where a period was 200 s, a temperature was 400 C., a constant pressure was 150 Pa, the silane had a flow rate of 700 sccm, and the laughing gas had a flow rate of 12000 sccm, a radio frequency power was 16000 W, and a pulse switching ratio was 1/50; (2) the obtained front-coated silicon wafer was subjected to back PECVD and laser grooving, and a crude silicon solar cell was obtained; and (3) the obtained crude silicon solar cell was subjected to screen printing and current injection, and then the all-black crystalline silicon solar cell was obtained; a method of the screen printing comprises: after loading and grooving the wafer, the crude silicon solar cell was subjected to a first printing and drying, a second printing and drying, a third printing and drying, and a fourth printing by using a gradient linewidth screen and drying, and sintering, and a linewidth of the cell was tested, and then the screen printing was completed; within 12 mm from an edge of the gradient linewidth screen to inside, the linewidth was reduced by 0.5 m every 4 mm, and a linewidth at the starting position was 21 m.

Example 3

(8) This example provides a method for preparing an all-black crystalline silicon solar cell, and the method comprises the following steps: (1) a film layer (FIG. 1) was deposited on the front surface of a silicon wafer 1 by a PECVD method, the film layer was a layered structure, and a front-coated silicon wafer was obtained; and the film layer comprised an innermost SiN.sub.x layer 2, an intermediate SiN.sub.x layer 3, a SiO.sub.xN.sub.y layer 4 and a SiO.sub.x layer 5 which were stacked from inside to outside; the innermost SiN.sub.x layer 2 had a thickness of 28 nm and a refractive index of 2.5; the SiO.sub.x layer 5 was the outermost layer, and had a thickness of 25 nm and a refractive index of 1.55; the deposition of the film layer in step (1) comprises the following steps: (a) after vacuuming, silane and ammonia gas were pre-introduced for 15 s at a constant pressure of 200 Pa, where the silane had a flow rate of 2200 sccm, the ammonia gas had a flow rate of 9000 sccm, and a temperature was 400 C.; (b) an innermost SiN.sub.x layer 2 was deposited on the front surface of the silicon wafer 1, where a deposition period was 60 s, a temperature was 600 C., a constant pressure was 200 Pa, the silane had a flow rate of 2200 sccm, the ammonia gas had a flow rate of 9000 sccm, a radio frequency power was 14000 W, and a pulse switching ratio was 5/70; (c) an intermediate SiN.sub.x layer 3 was deposited on the innermost SiN.sub.x layer 2, and a SiO.sub.xN.sub.y layer 4 was deposited on the intermediate SiN.sub.x layer 3; (d) after vacuuming, silane and laughing gas was pre-introduced for 15 s at a constant pressure of 150 Pa and a temperature of 400 C., where the silane had a flow rate of 600 sccm, and the laughing gas had a flow rate of 10000 sccm; and (e) a SiO.sub.x layer 5 was deposited on the SiO.sub.xN.sub.y layer 4, where a period was 190 s, a temperature was 500 C., a constant pressure was 130 Pa, the silane had a flow rate of 600 sccm, and the laughing gas had a flow rate of 10000 sccm, a radio frequency power was 14000 W, and a pulse switching ratio was 1/30; (2) the obtained front-coated silicon wafer was subjected to back PECVD and laser grooving, and a crude silicon solar cell was obtained; and (3) the obtained crude silicon solar cell was subjected to screen printing and current injection, and then the all-black crystalline silicon solar cell was obtained; a method of the screen printing comprises: after loading and grooving the wafer, the crude silicon solar cell was subjected to a first printing and drying, a second printing and drying, a third printing and drying, and a fourth printing by using a gradient linewidth screen and drying, and sintering, and the linewidth of the cell was tested, and then the screen printing was completed; within 15 mm from an edge of the gradient linewidth screen to inside, the linewidth was reduced by 1 m every 5 mm, and a linewidth at the starting position was 19 m.

Example 4

(9) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the innermost SiN.sub.x layer had a refractive index of 2.

Example 5

(10) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the SiO.sub.x layer had a refractive index of 1.3.

Example 6

(11) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the SiO.sub.x layer had a refractive index of 1.6.

Example 7

(12) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that in step (3), the gradient linewidth screen was replaced with a conventional screen.

Example 8

(13) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the innermost SiN.sub.x layer had a thickness of 55 nm.

Example 9

(14) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the SiO.sub.x layer had a thickness of 15 nm.

Example 10

(15) This example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the SiO.sub.x layer had a thickness of 45 nm.

Comparative Example 1

(16) This comparative example provides a method for preparing an all-black crystalline silicon solar cell, and this example is the same as Example 1 except that the innermost SiN.sub.x layer had a thickness of 15 nm.

Comparative Example 2

(17) This comparative example provides a method for preparing a silicon solar cell, and this method is obtained according to CN204497240U.

(18) The solar cells obtained by the above preparation methods were tested and detected, and the results are shown in Table 1.

(19) TABLE-US-00001 TABLE 1 Conversion Appearance Test Number Efficiency (Black Level) Example 1 23.28% 100% Example 2 23.30% 100% Example 3 23.29% 100% Example 4 23.31% 85% Example 5 23.30% 80% Example 6 23.31% 80% Example 7 23.32% 60% Example 8 23.00% 95% Example 9 23.27% 75% Example 10 23.15% 85% Comparative Example 1 23.33% 70% Comparative Example 2 23.20% 50%

(20) The following conclusions can be obtained from Table 1. (1) As can be seen from Examples 1-3, the preparation method provided in the present application affects the absorption and reflection effect of the incident light on the surface of the cell, so that almost all of the incident light is absorbed while only a very small amount is reflected, and thus an all-black crystalline silicon solar cell is obtained; meanwhile, the all-black crystalline silicon solar cell also has high conversion performance. (2) From the comparison of Example 4 with Example 1, when the refractive index of the innermost SiN.sub.x layer is less than 2.3, the prepared all-black crystalline silicon solar cell has a poor black effect. (3) From the comparison of Examples 5 and 6 with Example 1, when the refractive index of the SiO.sub.x layer is not within the range of 1.45-1.55 provided in the present application, the prepared all-black crystalline silicon solar cell has a poor black effect. (4) From the comparison of Example 7 with Example 1, when the gradient linewidth screen provided in the present application is not used, the edges of the prepared all-black crystalline silicon solar cell are blue. (5) From the comparison of Example 8 with Example 1, when the thickness of the innermost SiN.sub.x layer is more than 55 nm, the prepared all-black crystalline silicon solar cell has a poor black effect. (6) From the comparison of Examples 9 and 10 with Example 1, when the thickness of the SiO.sub.x layer is not within the range of 20-40 nm, the prepared all-black crystalline silicon solar cell has a poor black effect. (7) From the comparison of Comparative Example 1 with Example 1, when the thickness of the innermost SiN.sub.x layer is not within the range provided in the present application, i.e., the thickness of the innermost SiN.sub.x layer is less than 20 nm, the prepared all-black crystalline silicon solar cell has a poor black effect. (8) From the comparison of Comparative Example 2 with Example 1, the present application improves the black effect and conversion efficiency of the all-black crystalline silicon solar cell over the related technologies.

(21) The detailed structural features of the present application are illustrated by the above examples. However, the present application is not limited to the above structural features, that is, the present application is not necessarily rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present application, the equivalent replacement of the components selected in the present application, the addition of auxiliary components and the choice of specific methods all fall within the protection and disclosure scope of the present application.