CN106784049A - The preparation method and its obtained battery of a kind of local doped crystal silicon solar cell - Google Patents

Abstract

The invention provides a method for preparing a partially doped crystalline silicon solar cell and the resulting cell. The method comprises the following steps: depositing a passivation layer on the back of the crystalline silicon wafer, opening a partial opening on the passivation layer, and forming a partial opening on the passivation layer. Depositing a doping paste at the opening and doping on the backside; and optionally, depositing a first metal paste on the backside; wherein the size of the partial opening is smaller than the size of the deposited doping paste. By adjusting the size of the local opening on the back and the size of the deposited doping slurry, the invention can significantly increase the field strength of the back surface of the battery, reduce the recombination rate in the local area, and then greatly increase the open circuit voltage and fill factor, and finally greatly improve the conversion efficiency of the battery .

Description

A kind of preparation method of locally doped crystalline silicon solar cell and the cell thereof

technical field

The invention belongs to the field of solar cells, and relates to a method for preparing a locally doped crystalline silicon solar cell and the cell prepared therefrom, in particular to a method for preparing a locally doped solar cell by adjusting the size of the local opening on the back and the size of the deposited doping paste. A method for a crystalline silicon solar cell and the method prepares a partially doped crystalline silicon solar cell.

Background technique

With the development of science and technology, partial rear contact and rear passivation (PERC) solar cells have appeared, which is a newly developed high-efficiency solar cell and has received extensive attention from the industry. Its core is to cover the backlight surface of the silicon wafer with an aluminum oxide or silicon oxide film (5-100 nanometers) to passivate the surface and improve the long-wave response, thereby improving the conversion efficiency of the battery.

The existing PERC solar cell structure mainly includes a silicon wafer layer with a PN junction, and a passivation layer, a silicon nitride thin film layer and an aluminum metal layer successively arranged on the back side of the silicon wafer layer, such as CN 104882498A, CN 106057920A and CN105470349A. A PERC solar cell is disclosed. The preparation method of the PERC solar cell mainly includes the following steps: texturing, diffusion, back polishing, etching and de-impurity glass, deposition of a passivation layer (such as aluminum oxide, silicon oxide film or silicon nitride) on the back side, deposition of nitrogen on the front side Silicon anti-reflection layer, partial opening on the back, screen printing back silver paste, screen printing back aluminum paste, screen printing front silver paste and sintering, the structure of the solar cell made by the method is shown in Figure 1 shown.

It can be seen from Figure 3 that a P/P ⁺ structure is locally formed on the back of the silicon wafer through the substitutional doping of aluminum atoms in silicon, but due to the limitation of the solid solubility of aluminum atoms in silicon, the peak concentration of P ⁺ It can only reach 3×10 ¹⁸ cm ^-3 , which limits the cell conversion efficiency of solar cells.

In order to obtain higher battery conversion efficiency, the PERL structure was proposed by the State University of New South Wales, which is characterized in that boron atoms with high solid solubility in silicon are used to replace aluminum to form doping, and the doping concentration can reach 1×10 ¹⁹ ~5×10 ¹⁹ cm ⁻³ . Due to the increase of P ⁺ concentration, there is a stronger passivation of the back surface field locally, and a higher open circuit voltage and fill factor can be obtained.

Both CN 103996746A and CN 104638033A disclose a PERL solar cell and its preparation method. The PERL structure is shown in Figure 6. It can be seen that boron diffuses into the silicon wafer during high temperature or laser treatment, and at the opening of the passivation film Forming the P ⁺ area, because the boron concentration in the P ⁺ area is much higher than that of the P-type silicon wafer, a chemical potential difference is generated, and a local boron back field is formed, thereby improving the cell conversion efficiency of the solar cell.

The preparation methods of the existing PERL solar cells mainly include: texturing, diffusion, back etching, deposition of a passivation layer (such as aluminum oxide, silicon oxide film or silicon nitride) on the back side, deposition of a silicon nitride anti-reflection layer on the front side, and silk screen Printing boron paste, laser on the back side to complete film opening and boron doping at the same time, screen printing back silver paste, screen printing back aluminum paste, screen printing front silver paste and sintering. The preparation method of the PERL is characterized in that: the size of the laser doped region is 25 μm to 60 μm, which is smaller than the size of the deposited boron slurry.

The disadvantage of the above PERL preparation method is that the doping depth is only 6 μm-8 μm. When the aluminum paste is sintered, in a very small size, due to the violent reaction of silicon and aluminum, aluminum will drill into the silicon wafer as deep as possible, up to 20 μm, which is far deeper than the depth of boron doping. Therefore, most of the boron is diluted and left in the silicon-aluminum alloy, and a small amount is left in the silicon. The boron content in the silicon is only 10 ¹⁸ cm ^-3 . Within 0.1%, it also cannot effectively improve the cell conversion efficiency of solar cells.

Contents of the invention

In view of the problem that the performance of the solar cell cannot be further improved due to the low doping concentration of the existing PERC solar cell, and the boron-aluminum back field strength formed in the existing PERL solar cell is limited, which cannot effectively improve the cell conversion efficiency of the solar cell Moreover, the preparation process is cumbersome, the cost is high, and it is not conducive to industrial production. The present invention provides a method for preparing a partially doped crystalline silicon solar cell and the resulting cell. By adjusting the size of the local opening on the back and the size of the deposited doping slurry, the invention can significantly increase the field strength of the back surface of the battery, reduce the recombination rate in the local area, and then greatly increase the open circuit voltage and fill factor, and finally greatly improve the conversion efficiency of the battery .

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a method for preparing a locally doped crystalline silicon solar cell, the method comprising the following steps:

(1) Deposit a passivation layer on the back of the crystalline silicon wafer;

(2) Partial openings on the passivation layer;

(3) Depositing the doping slurry at the local opening;

(4) doping on the back;

Optionally, (5) depositing the first metal paste on the back side;

Wherein, the size of the local opening in step (2) is smaller than the size of the dopant slurry deposited in step (3).

In a second aspect, the present invention provides a method for preparing a locally doped crystalline silicon solar cell, the method comprising the following steps:

(A) depositing a passivation layer on the back side of the crystalline silicon wafer;

(B) depositing a doping paste on the passivation layer;

(C) Partial opening on the back side, and doping at the same time;

Optionally, (D) depositing a first metal paste on the back side;

Wherein, the size of the local opening in step (C) is smaller than the size of the dopant slurry deposited in step (B).

The preparation methods of the above two partially doped crystalline silicon solar cells are to adjust the size of the local opening on the back and the size of the doping slurry deposited. Closely, the violent reaction of silicon and aluminum during sintering makes aluminum enter the silicon body more along the width direction, and the depth does not exceed 4 μm, which is lower than the doping depth of elements in the doping paste. Therefore, most of the elements in the doping paste remain in the silicon, so that the content of the elements in the doping paste in silicon reaches 6×10 ¹⁹ cm ^-3 to 9×10 ²⁰ cm ^-3 , thereby effectively increasing the solar energy The battery conversion efficiency of the battery.

In each preparation method described in the present invention, the "local opening" is typically but not limited to a local point-like opening, that is, if each small opening domain is regarded as an "opening unit", multiple openings are opened on the back passivation layer. (≥2) "opening units".

In the above method, the size of the local opening is smaller than the size of the deposited doping slurry means that the area of the opening formed after acting on the back passivation layer is smaller than the area of the locally deposited doping slurry.

In each of the above-mentioned preparation methods, the crystalline silicon wafer also includes a pretreatment process before depositing a passivation layer on the back side. The pretreatment process includes texturing, diffusion, back etching, impurity-removing glass treatment, and front-side deposition of an anti-reflection layer. It is a conventional operation in the field, so the specific operation steps and parameters will not be repeated here.

In each of the above preparation methods, after each step, screen printing of silver paste on the front and back and sintering treatment are also included, which are routine operations in the field, so the specific operation steps and parameters will not be repeated here.

The following are preferred technical solutions of the present invention, but not as limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

As a preferred technical solution of the present invention, the way of partial opening in step (2) is laser opening or etching opening.

Preferably, the etching opening is a solution and/or slurry etching opening.

Preferably, the doping method in step (4) is any one or a combination of at least two of laser induction, thermal propulsion or ion implantation.

As a preferred technical solution of the present invention, the method of simultaneous doping and partial opening in step (C) is: using laser to form an opening on the passivation layer and performing laser doping at the same time.

As a preferred technical solution of the present invention, the size of the local openings in step (2) and step (C) are independently 100 μm to 200 μm, such as 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm, etc., but not limited to the listed values, other unlisted values within this range are also applicable.

Preferably, the size of the doping slurry deposited in step (3) and step (B) is independently 110 μm to 300 μm, such as 110 μm, 130 μm, 150 μm, 170 μm, 200 μm, 230 μm, 250 μm, 270 μm or 300 μm, etc., but not Not limited to the listed values, other unlisted values within the range of values are also applicable. That is, if each small area where the doping paste is deposited is regarded as a "doping paste unit", multiple (≥2) "doping paste units" are deposited on the passivation layer deposited on the back side, each The size of the "doped paste unit" is 40 μm to 200 μm.

As a preferred technical solution of the present invention, the crystalline silicon wafers in step (1) and step (A) are independently p-type silicon wafers.

Preferably, the deposition methods in the backside deposition passivation layer described in step (1) and step (A) are all independently any one or at least two of screen printing, chemical vapor deposition, physical vapor deposition or inkjet printing The combination.

Preferably, the passivation layer in the passivation layer deposited on the back side of step (1) and step (A) is independently any one of aluminum oxide, silicon nitride or silicon oxide film or a combination of at least two, so Typical but non-limiting examples of the above combinations are: the combination of aluminum oxide and silicon nitride, the combination of silicon nitride and silicon oxide film, the combination of aluminum oxide and silicon oxide film, the combination of aluminum oxide, silicon nitride and silicon oxide film Wait.

As a preferred technical solution of the present invention, the deposition methods in the deposition doping slurry described in step (3) and step (B) are all independently any one of screen printing, chemical vapor deposition, physical vapor deposition or inkjet printing A combination of one or at least two, preferably screen printing;

Preferably, the doping slurry in the deposited doping slurry described in step (3) and step (B) is a doping slurry of aluminum element and at least one element of the third main group whose solid solubility in silicon is greater than that of aluminum material, preferably boron slurry.

As a preferred technical solution of the present invention, the deposition methods in the first metal slurry deposited on the back side of step (5) and step (D) are all independently screen printing, chemical vapor deposition, physical vapor deposition or inkjet printing Either, preferably screen printing.

Preferably, the first metal paste deposited on the back side in step (5) and step (D) is aluminum paste.

In a third aspect, the present invention provides a partially doped crystalline silicon solar cell prepared by any one of the above preparation methods.

As a preferred technical solution of the present invention, the battery includes a crystalline silicon layer, a passivation layer and a first metal conductive layer arranged on the back of the crystalline silicon layer, the passivation layer has a plurality of openings, and the inside of the opening is The first metal paste is filled, and the crystalline silicon layer is sequentially doped into the crystalline silicon layer along the opening to form an alloy layer, a first doped back field and a second doped back field.

"Multiple" in the present invention means "at least 2".

As a preferred technical solution of the present invention, the height of the highest point of the alloy layer is 3 μm to 15 μm, such as 3 μm, 5 μm, 7 μm, 10 μm, 13 μm or 15 μm, etc., but it is not limited to the listed values. The enumerated values are also applicable, and here, the height is based on the interface between the crystalline silicon wafer and the passivation layer as the reference plane.

Preferably, the first doped back field is formed by doping aluminum elements.

Preferably, the thickness of the first doped back field is 0.5 μm to 3 μm, such as 0.5 μm, 0.7 μm, 1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 2 μm, 2.3 μm, 2.5 μm, 2.7 μm or 3 μm, etc., However, it is not limited to the listed values, and other unlisted values within the range of values are also applicable.

Preferably, the second doped back field is a back field formed by doping silicon with at least one element of the third main group whose solid solubility is greater than that of aluminum, preferably a boron back field.

Preferably, the height of the highest point of the second doped back field is 5 μm to 20 μm, such as 5 μm, 7 μm, 10 μm, 13 μm, 15 μm, 17 μm or 20 μm, etc., but not limited to the listed values, other values within this range Values not listed are also applicable. Here, the height is based on the interface between the crystalline silicon wafer and the passivation layer as a reference plane.

Preferably, the doping concentration of at least one element of the third main group whose solid solubility in silicon is greater than that of aluminum in the second doped back field is 6×10 ¹⁹ cm ^-3 to 9×10 ²⁰ cm ^-3 , For example, 7×10 ¹⁹ cm ^-3 , 9×10 ¹⁹ cm ^-3 , 1×10 ²⁰ cm ^-3 , 1.3×10 ²⁰ cm ^-3 , 1.5×10 ²⁰ cm ^-3 , 1.7×10 ²⁰ cm ^-3 , 2 ×10 ²⁰ cm ^-3 , 4×10 ²⁰ cm ^-3 , 6×10 ²⁰ cm ^-3 or 9×10 ²⁰ cm ^-3 , etc., but not limited to the listed values, other unlisted values within this range The same applies.

In the present invention, the crystalline silicon layer is a p-type silicon layer.

In the present invention, the passivation layer is any one or a combination of at least two of aluminum oxide, silicon nitride or silicon oxide films. Typical but non-limiting examples of the combination are: a combination of aluminum oxide and silicon nitride , A combination of silicon nitride and silicon oxide films, a combination of aluminum oxide and silicon oxide films, a combination of aluminum oxide, silicon nitride and silicon oxide films, etc.

The front side of the crystalline silicon sheet layer can also be sequentially provided with a textured diffusion layer, a textured anti-reflection layer, and a textured silver electrode, which are conventional settings for existing doped crystalline silicon cells, so they will not be described here.

The back silver electrodes can also be arranged distributedly on the back of the crystalline silicon layer, which is a conventional arrangement of existing doped crystalline silicon cells, so it will not be repeated here.

Compared with the prior art, the present invention has the following beneficial effects:

In the present invention, by adjusting the size of the local opening on the back and depositing the doping slurry, the size of the local opening is smaller than the size of the deposition doping slurry, and the doping concentration of boron in silicon is increased. For the existing PERC and PERL technologies, the P ⁺ concentration The peak can be increased from 3×10 ¹⁸ cm ^-3 to 6×10 ¹⁹ cm ^-3 ～9×10 ²⁰ cm ^-3 , which can significantly increase the field strength of the back surface of the battery, reduce the recombination rate in the local area, and then greatly increase the open circuit voltage and filling factor, and finally greatly improve the conversion efficiency of the battery.

At the same time, the preparation method of the partially doped crystalline silicon solar cell of the present invention is simpler and lower in cost than the existing PERL solar cell, and has higher compatibility with existing industrial equipment, which is beneficial to industrial production.

Description of drawings

Fig. 1 is the back top view of PERC solar cell structure described in prior art or comparative example 1;

2 is a partial enlarged top view of part A in the back top view of the PERC solar cell structure described in the prior art or Comparative Example 1;

Fig. 3 is a side view along the a-a' section in the partially enlarged top view of part A in the back top view of the PERC solar cell structure described in the prior art or Comparative Example 1;

Fig. 4 is the back top view of the PERL solar cell structure described in prior art or comparative example 2;

5 is a partial enlarged top view of part A in the back top view of the PERL solar cell structure described in the prior art or Comparative Example 2;

Fig. 6 is the side view along a-a' section in the partially enlarged top view of part A in the back top view of the PERL solar cell structure described in the prior art or comparative example 2;

Fig. 7 is a back top view of the partially doped crystalline silicon solar cell structure described in Embodiment 1 of the present invention;

Fig. 8 is a partially enlarged top view of part A in the back top view of the partially doped crystalline silicon solar cell structure described in Embodiment 1 of the present invention;

Fig. 9 is a side view along the a-a' section in the partially enlarged top view of part A of the back top view of the partially doped crystalline silicon solar cell structure described in Embodiment 1 of the present invention;

Among them, 1-crystalline silicon layer, 2-passivation layer, 3-first metal conductive layer, 4-silicon aluminum alloy, 5-aluminum back field, 6-boron back field, 7-texture diffusion layer, 8 - anti-reflection layer made of textured surface, 9 - silver electrode made of textured surface, 10 - back silver electrode, 11 - boron aluminum back field.

detailed description

In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention will be further described in detail below. However, the following embodiments are only simple examples of the present invention, and do not represent or limit the protection scope of the present invention, and the protection scope of the present invention shall be determined by the claims.

The specific embodiment part of the present invention provides a method for preparing a locally doped crystalline silicon solar cell,

One, the method includes the following steps:

(1) Deposit a passivation layer on the back of the crystalline silicon wafer;

(2) Partial openings on the passivation layer;

(3) Depositing the doping slurry at the local opening;

(4) doping on the back;

Optionally, (5) depositing the first metal paste on the back side;

Wherein, the size of the local opening in step (2) is smaller than the size of the dopant slurry deposited in step (3).

Its two, described method comprises the following steps:

(A) depositing a passivation layer on the back side of the crystalline silicon wafer;

(B) depositing a doping paste on the passivation layer;

(C) Partial opening on the back side, and doping at the same time;

Optionally, (D) depositing a first metal paste on the back side;

Wherein, the size of the local opening in step (C) is smaller than the size of the dopant slurry deposited in step (B).

The specific embodiment part of the present invention also provides a locally doped crystalline silicon solar cell made by any of the above preparation methods, said cell comprising a crystalline silicon layer 1 and a passivation layer 2 and The first metal conductive layer 3, the passivation layer 2 has a plurality of openings, the openings are filled with the first metal paste, and the crystalline silicon layer 1 is sequentially doped along the openings into the crystalline silicon layer. Alloy layer 4 , first doped back field 5 and second doped back field 6 .

The following are typical but non-limiting embodiments of the present invention:

Example 1:

This embodiment provides a partially doped crystalline silicon solar cell. The structure of the partially doped crystalline silicon solar cell is shown in FIGS. The passivation layer 2 and the first metal conductive layer 3 have a plurality of openings on the passivation layer 2, and the inside of the openings is filled with the first metal paste, and the crystalline silicon wafer layer 1 extends toward the crystalline silicon wafer along the openings. Layers are sequentially doped to form silicon-aluminum alloy 4, aluminum back field 5 and boron back field 6.

The front of the crystalline silicon layer 1 is provided with a textured diffusion layer 7 , a textured anti-reflection layer 8 and a textured silver electrode 9 in sequence; the back of the crystalline silicon layer 1 is distributed with back silver electrodes 10 .

Wherein, the passivation layer 2 is alumina, the first metal conductive layer 3 is an aluminum electrode layer, the height of the highest point of the silicon-aluminum alloy 4 is 8 μm, the thickness of the aluminum back field 5 is 2 μm; the height of the highest point of the boron back field 6 is The doping concentration of boron in the boron back field 6 is 7×10 ¹⁹ cm ^-3 .

The preparation method of the partially doped crystalline silicon solar cell is:

The crystalline silicon wafer is subjected to texturing, diffusion, back etching, impurity-removing glass treatment, and anti-reflection layer deposition on the front side in sequence, then a passivation layer is deposited on the back side, boron slurry is deposited on the passivation layer, and partial opening on the back side is carried out at the same time Doping, back screen printing aluminum paste, front screen printing silver paste, back screen printing silver paste and sintering treatment to obtain partially doped crystalline silicon solar cells; wherein, the local opening on the passivation layer is 100 μm, And smaller than the size of screen printing boron paste (120μm).

Example 2:

This embodiment provides a partially doped crystalline silicon solar cell and a preparation method thereof. The structure of the partially doped crystalline silicon solar cell is the same as that of the implementation except that the passivation layer 2 is a combination of aluminum oxide and silicon oxide films. Same as in Example 1.

In the preparation method of the partially doped crystalline silicon solar cell, except that the local opening on the passivation layer is 150 μm, and the size of the screen-printed boron paste is 190 μm, other preparation processes are the same as the preparation method in Example 1.

Through the above method, the height of the highest point of silicon-aluminum alloy 4 in the locally doped crystalline silicon solar cell is 6 μm, the thickness of the aluminum back field 5 is 2 μm; the height of the highest point of the boron back field 6 is 12 μm; the boron in the boron back field 6 The doping concentration is 1.2×10 ²⁰ cm ^-3 .

Example 3:

This embodiment provides a partially doped crystalline silicon solar cell and a preparation method thereof. The structure of the partially doped crystalline silicon solar cell is the same as that of the passivation layer 2 except that the passivation layer 2 is a combination of silicon nitride and silicon oxide films. Same as in Example 1.

The preparation method described in this example is the same as that in Example 1 except that the opening size of the partial opening is 190 μm, and the size of the screen printing boron paste is 240 μm.

Through the above method, the height of the highest point of silicon-aluminum alloy 4 in the locally doped crystalline silicon solar cell is 3.5 μm, the thickness of the aluminum back field 5 is 2 μm; the height of the highest point of the boron back field 6 is 10 μm; The doping concentration is 1.3×10 ²⁰ cm ^-3 .

Example 4:

This embodiment provides a partially doped crystalline silicon solar cell and a preparation method thereof. The structure of the partially doped crystalline silicon solar cell is the same as that in Embodiment 1 except that the passivation layer 2 is silicon nitride.

The preparation method of the partially doped crystalline silicon solar cell is the same as that in Example 1 except that the opening size of the local opening is 100 μm, and the size of the screen printing boron paste is 150 μm.

Through the above method, the height of the highest point of silicon-aluminum alloy 4 in the locally doped crystalline silicon solar cell is 4 μm, the thickness of the aluminum back field 5 is 2 μm; the height of the highest point of the boron back field 6 is 12 μm; the boron in the boron back field 6 The doping concentration is 7×10 ¹⁹ cm ^-3 .

Example 5:

This embodiment provides a partially doped crystalline silicon solar cell and a preparation method thereof. The structure of the partially doped crystalline silicon solar cell is the same as that in embodiment 1 except that the passivation layer 2 is a silicon oxide film.

In the preparation method of the partially doped crystalline silicon solar cell, except that the opening size of the partial opening is 200 μm, and the size of the screen printing boron paste is 300 μm, other preparation processes are the same as the preparation method in Example 1.

Through the above method, the height of the highest point of silicon-aluminum alloy 4 in the locally doped crystalline silicon solar cell is 5 μm, the thickness of the aluminum back field 5 is 2.5 μm; the height of the highest point of the boron back field 6 is 15 μm; The doping concentration is 3×10 ²⁰ cm ^-3 .

Comparative example 1:

This comparative example provides a PERC solar cell and its preparation method. As shown in Figures 1-3, the PERC solar cell includes a crystalline silicon layer 1 and a passivation layer 2 and The first metal conductive layer 3, the passivation layer 2 has a plurality of openings, the openings are filled with the first metal paste, and the crystalline silicon layer 1 is doped into the crystalline silicon layer 1 along the openings to form silicon Aluminum alloy 4 and aluminum back field 5.

The front of the crystalline silicon layer 1 is provided with a textured diffusion layer 7 , a textured anti-reflection layer 8 and a textured silver electrode 9 in sequence; the back of the crystalline silicon layer 1 is distributed with back silver electrodes 10 .

The preparation method of the PERC solar cell is as follows: sequentially pretreating the crystalline silicon wafer, depositing a passivation layer on the back, depositing an anti-reflection layer on the front, partially opening the back, depositing silver paste on the back, depositing aluminum paste on the back, and depositing silver paste on the front. Materials, silver paste deposition on the back and sintering treatment to obtain PERC solar cells.

Comparative example 2:

This comparative example provides a PERL solar cell and its preparation method, as shown in Figure 4-6, the PERC solar cell comprises a crystalline silicon layer 1 and a passivation layer 2 and The first metal conductive layer 3, the passivation layer 2 has a plurality of openings, the openings are filled with the first metal conductive paste, and the crystalline silicon layer 1 is formed by doping into the crystalline silicon layer along the openings Silicon aluminum alloy 4 and boron aluminum back field 11.

The front of the crystalline silicon layer 1 is provided with a textured diffusion layer 7 , a textured anti-reflection layer 8 and a textured silver electrode 9 in sequence; the back of the crystalline silicon layer 1 is distributed with back silver electrodes 10 .

The preparation method of the PERL solar cell is: texturing, diffusion, back etching, deposition of a passivation layer (such as aluminum oxide, silicon oxide film or silicon nitride) on the back side, deposition of a silicon nitride anti-reflection layer on the front side, screen printing Boron paste and backside laser complete film opening and boron doping at the same time, screen printing back silver paste, screen printing back aluminum paste, screen printing front silver paste and sintering. The size of the laser doped area is 25μm～60μm And smaller than the size after boron paste printing.

Performance test: The solar cells described in Examples 1-5 and Comparative Examples 1-2 were subjected to a performance test, and V _oc (open circuit voltage), I _sc (short circuit current), FF (fill factor), and Efficiency were measured at 25°C. (Photoelectric conversion efficiency) and back surface field p ⁺ peak doping concentration test results are shown in Table 1.

Table 1: Performance test table of solar cells in Examples 1-5 and Comparative Examples 1-2

Based on the results of Examples 1-5 and Comparative Examples 1-2, it can be seen that the present invention increases the doping concentration of boron in silicon by adjusting the size of the local opening on the back and depositing the doping slurry. For the existing PERC and PERL technologies, Its peak P ⁺ concentration can be increased from 3×10 ¹⁸ cm ^-3 to 6×10 ¹⁹ cm ^-3 ～9×10 ²⁰ cm ^-3 , which can significantly increase the field strength of the back surface of the battery, reduce the recombination rate in the local area, and thus greatly increase the The open circuit voltage and fill factor can greatly improve the conversion efficiency of the battery.

At the same time, the preparation method of the partially doped crystalline silicon solar cell of the present invention is simpler and lower in cost than the existing PERL solar cell, and has higher compatibility with existing industrial equipment, which is beneficial to industrial production.

The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow process can be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A preparation method for locally doped crystalline silicon solar cells, characterized in that the method comprises the following steps: (1) Deposit a passivation layer on the back of the crystalline silicon wafer; (2) Partial openings on the passivation layer; (3) Depositing the doping slurry at the local opening; (4) doping on the back; Optionally, (5) depositing the first metal paste on the back side; Wherein, the size of the local opening in step (2) is smaller than the size of the dopant slurry deposited in step (3). 2. A preparation method for locally doped crystalline silicon solar cells, characterized in that the method comprises the following steps: (A) depositing a passivation layer on the back side of the crystalline silicon wafer; (B) depositing a doping paste on the passivation layer; (C) Partial opening on the back side, and doping at the same time; Optionally, (D) depositing a first metal paste on the back side; Wherein, the size of the local opening in step (C) is smaller than the size of the dopant slurry deposited in step (B). 3. The preparation method according to claim 1, characterized in that, the mode of partial opening in step (2) is laser opening or corrosion opening; Preferably, the etching opening is a solution and/or slurry etching opening; Preferably, the doping method in step (4) is any one or a combination of at least two of laser induction, thermal propulsion or ion implantation. 4. The preparation method according to claim 2, the simultaneous doping and partial opening method in step (C) is: using a laser to form an opening on the passivation layer and performing laser doping at the same time. 5. The preparation method according to any one of claims 1-4, characterized in that, the sizes of the local openings in step (2) and step (C) are independently 100 μm to 200 μm; Preferably, the size of the doping slurry deposited in step (3) and step (B) is independently 110 μm to 300 μm. 6. The preparation method according to any one of claims 1-5, characterized in that, the crystalline silicon wafers described in step (1) and step (A) are all independently p-type silicon wafers; Preferably, the deposition methods in the backside deposition passivation layer described in step (1) and step (A) are all independently any one or at least two of screen printing, chemical vapor deposition, physical vapor deposition or inkjet printing The combination; Preferably, the passivation layer in the passivation layer deposited on the back side in step (1) and step (A) is independently any one or a combination of at least two of aluminum oxide, silicon nitride or silicon oxide films. 7. according to the preparation method described in any one of claim 1-6, it is characterized in that, the deposition method in the deposition doping slurry described in step (3) and step (B) is all independently screen printing, chemical Any one or a combination of at least two of vapor deposition, physical vapor deposition or inkjet printing, preferably screen printing; Preferably, the doping slurry in the deposited doping slurry described in step (3) and step (B) is a doping slurry of aluminum element and at least one element of the third main group whose solid solubility in silicon is greater than that of aluminum material, preferably boron slurry. 8. according to the preparation method described in any one of claim 1-7, it is characterized in that, step (5) and step (D) described in the deposition method in the back side deposition first metal paste are all independently screen printing , any one of chemical vapor deposition, physical vapor deposition or inkjet printing, preferably screen printing; Preferably, the first metal paste in the backside deposition of the first metal paste in step (5) and step (D) is aluminum paste. 9. A locally doped crystalline silicon solar cell prepared by the preparation method according to any one of claims 1-8. 10. The locally doped crystalline silicon solar cell according to claim 9, characterized in that the cell comprises a crystalline silicon layer (1) and a passivation layer (2) sequentially arranged on the back side of the crystalline silicon layer (1) ) and the first metal conductive layer (3), the passivation layer (2) has a plurality of openings, the inside of the opening is filled with the first metal paste, and the crystalline silicon layer (1) is along the opening to the crystal The silicon wafer layer is sequentially doped to form an alloy layer (4), a first doped back field (5) and a second doped back field (6); Preferably, the height of the highest point of the alloy layer (4) is 3 μm to 15 μm; Preferably, the first doped back field (5) is a back field formed by aluminum element doping; Preferably, the thickness of the first doped back field (5) is 0.5 μm to 3 μm; Preferably, the second doped back field (6) is a back field formed by doping silicon with at least one element of the third main group whose solid solubility is greater than that of aluminum, preferably a boron back field; Preferably, the height of the highest point of the second doped back field (6) is 5 μm to 20 μm; Preferably, the doping concentration of at least one element of the third main group whose solid solubility in silicon is greater than that of aluminum in the second doped back field (6) is 6×10 ¹⁹ cm ⁻³ to 9×10 ²⁰ cm ^-3 .