阅读说明：本技术 一种新型晶硅太阳电池及其制备方法 (Novel crystalline silicon solar cell and preparation method thereof ) 是由 张树德 魏青竹 况亚伟 钱洪强 丁可 揭建胜 张晓宏 李跃 连维飞 倪志春 刘玉 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种新型晶硅太阳电池,包括：第一背面N型硅和背面N型硅,所述第一背面N型硅和所述背面N型硅交替设置连接,第一背面N型硅的磷掺杂浓度大于背面N型硅的磷掺杂浓度；在保证P型硅片正表面钝化效果的前提下,规避硼扩散工艺,简化制备流程,此外,还减小背面N型硅区域的复合速率,提高电池效率。(The invention discloses a novel crystalline silicon solar cell, which comprises: the first back N-type silicon and the back N-type silicon are alternately arranged and connected, and the phosphorus doping concentration of the first back N-type silicon is greater than that of the back N-type silicon; on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.)

1. A novel crystalline silicon solar cell is characterized by comprising: the first back N-type silicon and the back N-type silicon are alternately arranged and connected, and the phosphorus doping concentration of the first back N-type silicon is greater than that of the back N-type silicon.

2. The novel crystalline silicon solar cell of claim 1, comprising: the second metal electrode penetrates through the back passivation layer and is in ohmic contact with the first back N-type silicon.

3. The novel crystalline silicon solar cell of claim 2, wherein the back passivation layer front side is provided with back N-type silicon.

4. The novel crystalline silicon solar cell of claim 3, comprising: the first metal electrode penetrates through the groove to be in ohmic contact with the P-type silicon, and a back passivation layer is arranged between the first metal electrode and the back N-type silicon at intervals.

5. The novel crystalline silicon solar cell of claim 4, wherein a P-type silicon wafer, a front N-type silicon and a front passivation layer are sequentially arranged from inside to outside on the front surface of the back N-type silicon.

6. A preparation method of a novel crystalline silicon solar cell is characterized by comprising the following steps:

1) texturing the surface of a P-type silicon wafer, and polishing the back surface of the P-type silicon wafer;

2) phosphorus is diffused on the front surface and the back surface of the P-type silicon wafer, and front N-type silicon, back N-type silicon, front phosphorosilicate glass and back phosphorosilicate glass are formed on the front surface and the back surface of the P-type silicon wafer;

3) laser doping is carried out on the back of the P-type silicon wafer, and the phosphorus doping concentration of a laser doping area is increased;

4) removing front phosphorosilicate glass and back phosphorosilicate glass from the front side and the back side of the P-type silicon wafer, carrying out laser grooving on the back side of the P-type silicon wafer, removing back side N-type silicon in a grooving region, and arranging the laser doping pattern in the step 3) and the laser grooving pattern in the step 4) in a staggered mode;

5) a front passivation layer and a back passivation layer are deposited on the front surface and the back surface of the P-type silicon wafer;

6) laser grooving is carried out on the back of the P-type silicon wafer, the position of the laser grooving graph in the step 6) is the same as that of the laser grooving graph in the step 4), the grooving width is smaller than that in the step 4), and a back passivation layer in the laser grooving area is removed;

7) and printing aluminum paste and silver paste on the back of the P-type silicon wafer, aligning the aluminum paste printing to the laser grooving region, aligning the silver paste to the laser doping region, and sintering.

7. The method for preparing a novel crystalline silicon solar cell according to claim 6, wherein the front side phosphorosilicate glass and the back side phosphorosilicate glass on the front side and the back side of the P-type silicon wafer are removed by hydrofluoric acid in the step 4), and the laser grooving pattern is a grid line.

8. The preparation method of the novel crystalline silicon solar cell as claimed in claim 6, wherein in the step 5), the front surface and the back surface of the P-type silicon wafer are subjected to soaking oxidation to form a silicon oxide layer, silicon nitride is deposited on the front surface and the back surface of the silicon oxide layer to form a front passivation layer and a back passivation layer, and the front passivation layer and the back passivation layer are stacked layers of silicon oxide and silicon nitride.

9. The preparation method of the novel crystalline silicon solar cell according to claim 6, characterized in that in the step 7), the back of the P-type silicon wafer is printed with aluminum paste and silver paste, the aluminum gate lines are aligned with the laser grooving region in the step 6), the silver gate lines are aligned with the laser doping region in the step 3), after sintering, P-type silicon is formed at the interface between the aluminum paste and the P-type silicon wafer, and the silver paste is burned through the back passivation layer and is in contact with the first back N-type silicon.

10. The method for preparing a novel crystalline silicon solar cell according to claim 6, wherein the back side of the P-type silicon wafer printed with the aluminum paste and the silver paste patterns in step 7) are both grid lines.

Technical Field

The invention relates to the technical field of solar cells, in particular to a novel crystalline silicon solar cell and a preparation method thereof.

Background

Compared with the conventional crystalline silicon solar cell, the front surface of the IBC (intermediate Back contact) cell has no electrode, and light rays cannot be shielded, so that the optical loss is less, the photoelectric conversion efficiency can be higher, and the method is a research hotspot in the photovoltaic industry. At present, most of IBC (ion-beam copper-based carbon) batteries are researched on the basis of N-type silicon wafers, but the N-type silicon wafers are high in cost and not beneficial to commercial application, and with the continuous improvement of minority carrier lifetime of the P-type silicon wafers, the P-type IBC batteries become an important development direction of future crystalline silicon solar batteries.

In the front side of an IBC cell, it is usually necessary to produce a highly concentrated doped layer, called the front surface field, to reduce the recombination rate at the front surface of the cell by field effect passivation. However, in the prior art, the front surface field of the P-type IBC cell is prepared by adopting a boron diffusion process, multiple masks and cleaning are required, the preparation process is complex, and the high-temperature boron diffusion process above 950 ℃ can affect the minority carrier lifetime of the P-type silicon wafer, thereby affecting the cell efficiency. In addition, the back N-type silicon doping concentration is high and the recombination rate is high in the prior art.

Therefore, a novel crystalline silicon solar cell and a preparation method thereof are urgently needed, a boron diffusion process is avoided on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the cell efficiency is improved.

Disclosure of Invention

In order to solve the technical problems, the invention provides a novel crystalline silicon solar cell and a preparation method thereof, which avoid a boron diffusion process and simplify a preparation process on the premise of ensuring the front surface passivation effect of a P-type silicon wafer, and in addition, reduce the recombination rate of a back N-type silicon region and improve the cell efficiency.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a novel crystalline silicon solar cell includes: the first back N-type silicon and the back N-type silicon are alternately arranged and connected, and the phosphorus doping concentration of the first back N-type silicon is greater than that of the back N-type silicon.

According to the novel crystalline silicon solar cell and the preparation method thereof, provided by the invention, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, a boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the cell efficiency is improved.

On the basis of the technical scheme, the following improvements can be made:

preferably, the novel crystalline silicon solar cell includes: the second metal electrode penetrates through the back passivation layer and is in ohmic contact with the first back N-type silicon.

Preferably, the front surface of the back passivation layer is provided with back N-type silicon.

Preferably, the novel crystalline silicon solar cell includes: the first metal electrode penetrates through the groove to be in ohmic contact with the P-type silicon, and a back passivation layer is arranged between the first metal electrode and the back N-type silicon at intervals.

Preferably, a P-type silicon wafer, a front N-type silicon and a front passivation layer are sequentially arranged from inside to outside on the front of the back N-type silicon.

As a preferable scheme, the preparation method of the novel crystalline silicon solar cell comprises the following steps:

1) texturing the surface of a P-type silicon wafer, and polishing the back surface of the P-type silicon wafer;

2) phosphorus is diffused on the front surface and the back surface of the P-type silicon wafer, and front N-type silicon, back N-type silicon, front phosphorosilicate glass and back phosphorosilicate glass are formed on the front surface and the back surface of the P-type silicon wafer;

3) laser doping is carried out on the back of the P-type silicon wafer, and the phosphorus doping concentration of a laser doping area is increased;

4) removing front phosphorosilicate glass and back phosphorosilicate glass from the front side and the back side of the P-type silicon wafer, carrying out laser grooving on the back side of the P-type silicon wafer, removing back side N-type silicon in a grooving region, and arranging the laser doping pattern in the step 3) and the laser grooving pattern in the step 4) in a staggered mode;

5) a front passivation layer and a back passivation layer are deposited on the front surface and the back surface of the P-type silicon wafer;

6) laser grooving is carried out on the back of the P-type silicon wafer, the position of the laser grooving graph in the step 6) is the same as that of the laser grooving graph in the step 4), the grooving width is smaller than that in the step 4), and a back passivation layer in the laser grooving area is removed;

7) and printing aluminum paste and silver paste on the back of the P-type silicon wafer, aligning the aluminum paste printing to the laser grooving region, aligning the silver paste to the laser doping region, and sintering.

Preferably, in the step 4), hydrofluoric acid is used for removing the front phosphorosilicate glass and the back phosphorosilicate glass on the front surface and the back surface of the P-type silicon wafer, and the laser grooving pattern is a grid line.

Preferably, in the step 5), the front surface and the back surface of the P-type silicon wafer are subjected to soaking oxidation to form a silicon oxide layer, and silicon nitride is deposited on the front surface and the back surface of the silicon oxide layer to form a front passivation layer and a back passivation layer, wherein the front passivation layer and the back passivation layer are stacked layers of silicon oxide and silicon nitride.

As a preferable scheme, in the step 7), the back of the P-type silicon wafer is printed with aluminum paste and silver paste, the aluminum gate line is aligned with the laser grooving region in the step 6), the silver gate line is aligned with the laser doping region in the step 3), after sintering, P-type silicon is formed at the interface between the aluminum paste and the P-type silicon wafer, and the silver paste is burnt through the back passivation layer and is in contact with the first back N-type silicon.

Preferably, the patterns printed by the aluminum paste and the silver paste on the back surface of the P-type silicon wafer in the step 7) are grid lines.

Drawings

Fig. 1 is a structural diagram of a novel crystalline silicon solar cell according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for manufacturing a novel crystalline silicon solar cell according to an embodiment of the present invention.

1. The solar cell comprises a front passivation layer, 2 front N-type silicon, 3P-type silicon, 4 back N-type silicon, 5 back passivation layer, 6P-type silicon, 7 first metal electrode, 8 first back N-type silicon and 9 second metal electrode.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In order to achieve the object of the present invention, as shown in fig. 1-2, a novel crystalline silicon solar cell in this embodiment includes: the first back N-type silicon 8 and the back N-type silicon 4 are alternately arranged and connected, and the phosphorus doping concentration of the first back N-type silicon 8 is greater than that of the back N-type silicon 4.

According to the novel crystalline silicon solar cell and the preparation method thereof, provided by the invention, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, a boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the cell efficiency is improved.

In some embodiments, a novel crystalline silicon solar cell, comprises: a second metal electrode 9 and a back passivation layer 5, said second metal electrode 9 penetrating through said back passivation layer 5 and being in ohmic contact with the first back N-type silicon 8.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, the back passivation layer 5 is provided with a back N-type silicon 4 on the front side.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, a novel crystalline silicon solar cell, comprises: the back surface N-type silicon 4 and the back surface passivation layer 5 are provided with grooves, the first metal electrode 7 penetrates through the grooves to be in ohmic contact with the P-type silicon 6, and the back surface passivation layer 5 is arranged between the first metal electrode 7 and the back surface N-type silicon 4 at intervals.

With the above embodiment, when the back passivation layer is disposed between the first metal electrode and the back N-type silicon, it is possible to prevent the first metal electrode 7 and the back N-type silicon 4 from being contacted to cause electric leakage.

In some embodiments, a P-type silicon wafer 3, a front N-type silicon 2 and a front passivation layer 1 are sequentially arranged from inside to outside on the front surface of the back N-type silicon 4.

With the above embodiment, the front passivation layer 1 functions as an antireflection.

In some embodiments, a method for manufacturing a novel crystalline silicon solar cell includes the following steps:

1) texturing the surface of the P-type silicon wafer 3, and polishing the back surface of the P-type silicon wafer 3;

2) phosphorus is diffused on the front surface and the back surface of the P-type silicon wafer 3, and front N-type silicon 2, back N-type silicon 4, front phosphorosilicate glass and back phosphorosilicate glass are formed on the front surface and the back surface of the P-type silicon wafer 3;

3) laser doping is carried out on the back of the P-type silicon wafer 3, and the phosphorus doping concentration of a laser doping area is increased;

4) removing front phosphorosilicate glass and back phosphorosilicate glass from the front and back surfaces of the P-type silicon wafer 3, carrying out laser grooving on the back surface of the P-type silicon wafer 3, removing back N-type silicon 4 in a grooving region, and arranging the laser doping pattern in the step 3) and the laser grooving pattern in the step 4) in a staggered mode;

5) a front passivation layer 1 and a back passivation layer 5 are deposited on the front surface and the back surface of the P-type silicon wafer 3;

6) laser grooving is carried out on the back of the P-type silicon wafer 3, the positions of the laser grooving graph in the step 6) and the laser grooving graph in the step 4) are the same, the grooving width in the step 6) is smaller than that in the step 4), and the back passivation layer 5 in the laser grooving area is removed;

7) and printing aluminum paste and silver paste on the back surface of the P-type silicon wafer 3, aligning the aluminum paste printing to the laser grooving area, aligning the silver paste to the laser doping area, and sintering.

By adopting the embodiment, on the premise of ensuring the front surface passivation effect, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, hydrofluoric acid is used to remove the front side phosphorosilicate glass and the back side phosphorosilicate glass on the front side and the back side of the P-type silicon wafer 3 in the step 4), and the laser grooving pattern is a grid line.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, the front side and the back side of the P-type silicon wafer 3 are subjected to soaking oxidation in the step 5) to form a silicon oxide layer, and silicon nitride is deposited on the front side and the back side of the silicon oxide layer to form a front passivation layer 1 and a back passivation layer 5, wherein the front passivation layer 1 and the back passivation layer 5 are stacked layers of silicon oxide and silicon nitride.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, the back surface of the P-type silicon wafer 3 in the step 7) is printed with aluminum paste and silver paste, the aluminum gate lines are aligned with the laser grooving region in the step 6), the silver gate lines are aligned with the laser doping region in the step 3), after sintering, P-type silicon is formed at the interface of the aluminum paste and the P-type silicon wafer 3, and the silver paste is sintered to penetrate through the back passivation layer 5 and to contact with the first back surface N-type silicon 8.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

In some embodiments, the back side of the P-type silicon wafer 3 printed in the step 7) is printed with aluminum paste and silver paste patterns which are grid lines.

By adopting the embodiment, on the premise of ensuring the passivation effect of the front surface of the P-type silicon wafer, the boron diffusion process is avoided, the preparation flow is simplified, in addition, the recombination rate of the back N-type silicon region is reduced, and the battery efficiency is improved.

According to the novel crystalline silicon solar cell provided by the invention, the P-type silicon wafer 3 is a boron or gallium doped P-type silicon substrate, the front N-type silicon 2 with lower phosphorus doping concentration is arranged on the front side of the P-type silicon wafer 3, and the front N-type silicon 2 is connected with the P-type silicon wafer 3 to form a floating junction. And a front passivation layer 1 is arranged on the front surface of the front N-type silicon 2, the front passivation layer 1 simultaneously plays a role of antireflection, and the front passivation layer 1 is silicon nitride or a laminated layer of silicon oxide and silicon nitride. The back surface N-type silicon 4 with low phosphorus doping concentration is arranged on the back surface of the P-type silicon wafer 3, and the back surface N-type silicon 4 is connected with the P-type silicon wafer 3 to form a PN junction. And a back passivation layer 5 is arranged on the back surface of the N-type silicon 4, and the back passivation layer 5 is silicon nitride or a laminated layer of silicon oxide and silicon nitride. The back N-type silicon 4 and the back passivation layer 5 are both provided with open grooves, the open grooves are open holes, the first metal electrode 7 penetrates through the open grooves to be in ohmic contact with the P-type silicon 6, the first metal electrode 7 can be aluminum, the P-type silicon 6 is also called a local back surface field, and the P-type silicon 6 is silicon with higher aluminum doping concentration. The first metal electrode 7 and the back surface N-type silicon 4 are separated by the back surface passivation layer 5, and the first metal electrode 7 and the back surface N-type silicon 4 are prevented from being contacted to cause electric leakage. In addition, the first back N-type silicon 8 with higher phosphorus doping concentration and the back N-type silicon 4 are alternately arranged and connected, the second metal electrode 9 penetrates through the back passivation layer 5 to be in ohmic contact with the first back N-type silicon 8, and the second metal electrode 9 can be silver.

The front N-type silicon 2 with low phosphorus doping concentration has the sheet resistance of 100-200 omega/sq; the back N-type silicon 4 with low phosphorus doping concentration has the sheet resistance of 100-200 omega/sq; the first back N-type silicon 8 with higher phosphorus doping concentration has the sheet resistance of 50-100 omega/sq; the P-type silicon 6 is silicon with higher aluminum doping concentration and the doping concentration is 1E18cm^-3～1E19cm^-3。

The invention provides a novel crystalline silicon solar cell, which comprises the following steps:

1) texturing the surface of the P-type silicon wafer 3, and polishing the back surface of the P-type silicon wafer to form a structure that the front surface of the P-type silicon wafer 3 is textured and the back surface of the P-type silicon wafer 3 is flat;

2) p type silicon chip 3 front and back two-sided phosphorus diffusion, form the lower N type silicon of phosphorus doping concentration at P type silicon chip 3 front and back two-sided, N type silicon includes: front N-type silicon 2 and back N-type silicon 4, and phosphorus-silicon glass formed by phosphorus diffusion is arranged on the surface of the N-type silicon;

3) the back of the P-type silicon wafer 3 is doped with the back N-type silicon 4 by laser, the phosphorus doping concentration of the laser doping area is increased, the first back N-type silicon 8 is obtained, and the laser doping graph is a grid line.

4) Removing phosphorosilicate glass on the front side and the back side of the P-type silicon wafer 3 by using hydrofluoric acid, carrying out laser grooving on the back side, removing N-type silicon 4 on the back side in a grooving area, wherein a grooving pattern is a grid line, and the laser doping pattern in the step 3) and the laser grooving pattern in the step 4) are arranged in a staggered mode.

5) And thermally oxidizing the front surface and the back surface of the P-type silicon wafer 3 to form a silicon oxide thin layer, wherein the thickness of the silicon oxide thin layer is 1-10 nm, depositing silicon nitride on the front surface and the back surface of the P-type silicon wafer 3 respectively through PECVD (plasma enhanced chemical vapor deposition), and forming a front passivation layer 1 and a back passivation layer 5, wherein the front passivation layer 1 and the back passivation layer 5 are both silicon oxide and silicon nitride laminated layers.

6) And (3) carrying out laser grooving on the back of the P-type silicon wafer 3, wherein the laser grooving graph in the step 6) is the same as the laser grooving graph in the step 4), but the width of the grid line is thinner, and the back passivation layer 5 in the grooving area is removed to expose the P-type silicon wafer 3.

7) Printing aluminum paste and silver paste on the back of the P-type silicon wafer 3, wherein the printed patterns are grid lines, the aluminum grid lines are aligned to the laser grooving region in the step 6), the silver grid lines are aligned to the laser doping region in the step 3), after sintering, P-type silicon 6 with high aluminum doping concentration is formed at the interface of the aluminum paste and the P-type silicon wafer 3, the silver paste penetrates through the back passivation layer 5, and the silver paste is in contact with first back N-type silicon 8 with high back phosphorus doping concentration.

The invention provides a novel crystalline silicon solar cell and a preparation method thereof, and the novel crystalline silicon solar cell has the following beneficial effects:

1) the invention provides a novel crystalline silicon solar cell and a preparation method thereof.A floating junction is used as a passivation structure of the front surface of a P-type silicon chip, and on the premise of ensuring the passivation effect of the front surface, a high-temperature boron diffusion process is avoided, so that the preparation flow is simplified, and the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided.

2) The phosphorus doping of the front side and the back side of the P-type silicon wafer is completed by one-step diffusion, so that the diffusion reaction efficiency is improved;

3) the invention provides a novel crystalline silicon solar cell and a preparation method thereof.A selective contact structure is adopted on the back surface of a P-type silicon wafer, so that the recombination rate of a back N-type silicon region is reduced and the cell efficiency is improved while the back N-type silicon and a metal electrode have smaller contact resistance.

A preparation method of a novel crystalline silicon solar cell is applied to a solar cell product.

The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the inventive concept of the present invention, which falls into the protection scope of the present invention.