阅读说明：本技术 一种晶硅太阳电池及其制备方法 (Crystal 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：本发明公开了一种晶硅太阳电池,包括：P型硅基体,所述P型硅基体正面设有正面N型硅,所述P型硅基体与所述正面N型硅连接形成浮动结；采用浮动结作为正面的钝化结构,在保证正面钝化效果的前提下,一方面简化制备流程,另一方面规避了硼扩散的高温对P型硅基体少子寿命的影响,提高了电池的效率。(The invention discloses a crystalline silicon solar cell, comprising: the front surface of the P-type silicon substrate is provided with front N-type silicon, and the P-type silicon substrate and the front N-type silicon are connected to form a floating junction; the floating junction is used as a passivation structure of the front surface, so that on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.)

1. A crystalline silicon solar cell, comprising: the front surface of the P-type silicon substrate is provided with front N-type silicon, and the P-type silicon substrate and the front N-type silicon are connected to form a floating junction.

2. The crystalline silicon solar cell of claim 1, wherein the front side of the front side N-type silicon is provided with a front side passivation layer.

3. The crystalline silicon solar cell of claim 1, wherein a back N-type silicon is disposed on a back surface of the P-type silicon substrate, and the P-type silicon substrate and the back N-type silicon are connected to form a PN junction.

4. The crystalline silicon solar cell according to claim 3, characterized by comprising: and a back passivation layer is arranged between the first metal electrode and the back N-type silicon at intervals.

5. The crystalline silicon solar cell according to claim 4, characterized by comprising: and the P-type silicon, the back N-type silicon and the back passivation layer are both provided with a slot, and the first metal electrode penetrates through the slot and is in ohmic contact with the P-type silicon.

6. The crystalline silicon solar cell according to claim 5, characterized by comprising: and the second metal electrode penetrates through the back passivation layer and is in ohmic contact with the back N-type silicon.

7. A preparation method of a crystal silicon solar cell is characterized by comprising the following steps:

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

2) phosphorus is diffused on the front surface and the back surface of the P-type silicon substrate, 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 substrate;

3) removing the front phosphorosilicate glass of the P-type silicon substrate, reserving the back phosphorosilicate glass of the P-type silicon substrate, back-etching the front N-type silicon, and protecting and reserving the back N-type silicon through the back phosphorosilicate glass of the P-type silicon substrate;

4) removing the phosphorosilicate glass on the back of the P-type silicon substrate, performing laser grooving on the back of the P-type silicon substrate, and removing the N-type silicon on the back in a laser grooving area;

5) depositing a front passivation layer and a back passivation layer on the front surface and the back surface of the P-type silicon substrate;

6) laser grooving is carried out on the back of the P-type silicon substrate, the grooving graph and the grooving graph in the step 4) are grid lines, 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 substrate, aligning the aluminum paste printing to the laser grooving area, and sintering to complete metallization.

8. The method for preparing a crystalline silicon solar cell according to claim 7, characterized in that hydrofluoric acid is used to remove the front phosphosilicate glass of the P-type silicon substrate in the step 3), the back phosphosilicate glass of the P-type silicon substrate is remained, the back etching is performed on the front N-type silicon by using alkali solution, the phosphorus doping concentration of the front N-type silicon is reduced, and the back N-type silicon is protected and remained through the back phosphosilicate glass of the P-type silicon substrate.

9. The method for preparing a crystalline silicon solar cell according to claim 7, wherein in the step 5), the front surface and the back surface of the P-type silicon substrate are thermally oxidized to form a silicon oxide layer, silicon nitride is deposited on the front surface and the back surface of the P-type silicon substrate to obtain a front passivation layer and a back passivation layer, and the front passivation layer and the back passivation layer are both silicon nitride or a silicon oxide and silicon nitride lamination.

10. The method for preparing the crystalline silicon solar cell according to claim 7, characterized in that aluminum paste and silver paste are printed on the back surface of the P-type silicon substrate in the step 7), the printed patterns are aluminum grid lines and silver grid lines, the aluminum grid lines are aligned with the laser grooving regions in the step 6), after sintering, P-type silicon is formed at the interface of the aluminum paste and the P-type silicon substrate, and the silver paste burns through the back passivation layer and is in contact with the back N-type silicon.

Technical Field

The invention relates to the technical field of solar cells, in particular to a 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.

Therefore, a need exists for a crystalline silicon solar cell and a preparation method thereof, wherein a floating junction is used as a passivation structure of a front surface, on the premise of ensuring a front surface passivation effect, on one hand, a preparation process is simplified, on the other hand, the influence of high temperature of boron diffusion on the minority carrier lifetime of a P-type silicon substrate is avoided, and the efficiency of the cell is improved.

Disclosure of Invention

In order to solve the technical problems, the invention provides a crystalline silicon solar cell and a preparation method thereof, wherein a floating junction is used as a passivation structure of the front surface, on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation flow is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of a P-type silicon substrate is avoided, and the efficiency of the cell is improved.

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

a crystalline silicon solar cell, comprising: the front surface of the P-type silicon substrate is provided with front N-type silicon, and the P-type silicon substrate and the front N-type silicon are connected to form a floating junction.

According to the crystalline silicon solar cell and the preparation method thereof, the floating junction is used as the passivation structure of the front surface, on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation flow is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the cell is improved.

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

preferably, the front surface of the front surface N-type silicon is provided with a front surface passivation layer.

Preferably, back N-type silicon is arranged on the back of the P-type silicon substrate, and the P-type silicon substrate and the back N-type silicon are connected to form a PN junction.

Preferably, the crystalline silicon solar cell includes: and a back passivation layer is arranged between the first metal electrode and the back N-type silicon at intervals.

Preferably, the crystalline silicon solar cell includes: and the P-type silicon, the back N-type silicon and the back passivation layer are both provided with a slot, and the first metal electrode penetrates through the slot and is in ohmic contact with the P-type silicon.

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

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

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

2) phosphorus is diffused on the front surface and the back surface of the P-type silicon substrate, 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 substrate;

3) removing the front phosphorosilicate glass of the P-type silicon substrate, reserving the back phosphorosilicate glass of the P-type silicon substrate, back-etching the front N-type silicon, and protecting and reserving the back N-type silicon through the back phosphorosilicate glass of the P-type silicon substrate;

4) removing the phosphorosilicate glass on the back of the P-type silicon substrate, performing laser grooving on the back of the P-type silicon substrate, and removing the N-type silicon on the back in a laser grooving area;

5) depositing a front passivation layer and a back passivation layer on the front surface and the back surface of the P-type silicon substrate;

6) laser grooving is carried out on the back of the P-type silicon substrate, the grooving graph and the grooving graph in the step 4) are grid lines, 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 substrate, aligning the aluminum paste printing to the laser grooving area, and sintering to complete metallization.

Preferably, in the step 3), hydrofluoric acid is used to remove the front phosphosilicate glass of the P-type silicon substrate, the back phosphosilicate glass of the P-type silicon substrate is reserved, the back N-type silicon of the front is etched back by using an alkali solution, the phosphorus doping concentration of the front N-type silicon is reduced, and the back N-type silicon is protected and reserved through the back phosphosilicate glass of the P-type silicon substrate.

Preferably, in the step 5), both the front surface and the back surface of the P-type silicon substrate are thermally oxidized to form a silicon oxide layer, and silicon nitride is deposited on both the front surface and the back surface of the P-type silicon substrate to obtain a front passivation layer and a back passivation layer, wherein both the front passivation layer and the back passivation layer are silicon nitride or a stacked layer of silicon oxide and silicon nitride.

Preferably, aluminum paste and silver paste are printed on the back surface of the P-type silicon substrate in the step 7), the printed patterns are aluminum grid lines and silver grid lines, the aluminum grid lines are aligned with the laser grooving area in the step 6), P-type silicon is formed on the interface of the aluminum paste and the P-type silicon substrate after sintering, and the silver paste is burnt through a back passivation layer and is in contact with back N-type silicon.

Drawings

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

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

1. The semiconductor device comprises a front passivation layer, 2 front N-type silicon, 3P-type silicon substrate, 4 back N-type silicon, 5 back passivation layer, 6P-type silicon, 7 first metal electrode and 8 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 crystalline silicon solar cell in the present embodiment includes: the silicon solar cell comprises a P-type silicon substrate 3, wherein the front surface of the P-type silicon substrate 3 is provided with a front N-type silicon 2, and the P-type silicon substrate 3 and the front N-type silicon 2 are connected to form a floating junction.

According to the crystalline silicon solar cell and the preparation method thereof, the floating junction is used as the passivation structure of the front surface, on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation flow is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the cell is improved.

In some embodiments, the front side of the front side N-type silicon 2 is provided with a front side passivation layer 1.

With the above embodiment, the front passivation layer 1 simultaneously functions as an antireflection, and the front passivation layer 1 is silicon nitride or a stack of silicon oxide and silicon nitride.

In some embodiments, the back surface of the P-type silicon substrate 3 is provided with a back N-type silicon 4, and the P-type silicon substrate 3 and the back N-type silicon 4 are connected to form a PN junction.

With the above embodiment, the phosphorus doping concentration of the back N-type silicon is greater than the phosphorus doping concentration of the front N-type silicon.

In some embodiments, a crystalline silicon solar cell, comprises: and a back passivation layer 5 is arranged between the first metal electrode 7 and the back N-type silicon 4 at an interval.

With the above embodiment, the first metal electrode 7 and the back surface N-type silicon 4 are separated by the back surface passivation layer 5, preventing leakage current from contacting both the first metal electrode 7 and the back surface N-type silicon.

In some embodiments, a crystalline silicon solar cell, comprises: and the P-type silicon 6 is provided with grooves on the back N-type silicon 4 and the back passivation layer 5, and the first metal electrode 7 penetrates through the grooves and is in ohmic contact with the P-type silicon 6.

By adopting the embodiment, the battery pack is simple in structure and convenient to operate, and the efficiency of the battery is improved.

In some embodiments, a crystalline silicon solar cell, comprises: a second metal electrode 8, the second metal electrode 8 penetrating through the back passivation layer 5 and being in ohmic contact with the back N-type silicon 4.

By adopting the embodiment, the battery pack is simple in structure and convenient to operate, and the efficiency of the battery is improved.

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

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

2) phosphorus is diffused on both the front surface and the back surface of the P-type silicon substrate 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 substrate 3;

3) removing the front phosphorosilicate glass of the P-type silicon substrate 3, reserving the back phosphorosilicate glass of the P-type silicon substrate 3, back-etching the front N-type silicon 2, and protecting and reserving the back N-type silicon 4 through the back phosphorosilicate glass of the P-type silicon substrate 3;

4) removing the phosphorosilicate glass on the back of the P-type silicon substrate 3, performing laser grooving on the back of the P-type silicon substrate 3, and removing the N-type silicon 4 on the back in a laser grooving region;

5) depositing a front passivation layer 1 and a back passivation layer 5 on the front surface and the back surface of the P-type silicon substrate 3;

6) laser grooving is carried out on the back of the P-type silicon substrate 3, the grooving graph and the grooving graph in the step 4) are grid lines, the grooving width 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 of the P-type silicon substrate 3, aligning the printing of the aluminum paste to a laser grooving area, and sintering to finish metallization.

By adopting the embodiment and adopting the floating junction as the passivation structure of the front surface, on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.

In some embodiments, hydrofluoric acid is used to remove the front phosphorosilicate glass of the P-type silicon substrate 3 in the step 3), the back phosphorosilicate glass of the P-type silicon substrate 3 is reserved, the front N-type silicon 2 is etched back by using alkali solution, the phosphorus doping concentration of the front N-type silicon 2 is reduced, and the back N-type silicon 4 is protected and reserved through the back phosphorosilicate glass of the P-type silicon substrate 3.

With the above embodiment, the phosphorus doping concentration of the back N-type silicon 4 is greater than the phosphorus doping concentration of the front N-type silicon 2; on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.

In some embodiments, the front and back surfaces of the P-type silicon substrate 3 in step 5) are thermally oxidized to form a silicon oxide layer, silicon nitride is deposited on the front and back surfaces of the P-type silicon substrate 3 to obtain a front passivation layer 1 and a back passivation layer 5, and the front passivation layer 1 and the back passivation layer 5 are both silicon nitride or a stack of silicon oxide and silicon nitride.

By adopting the embodiment, on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.

In some embodiments, the back side of the P-type silicon substrate 3 in the step 7) is printed with aluminum paste and silver paste, the printed patterns are aluminum grid lines and silver grid lines, the aluminum grid lines are aligned with the laser grooving area in the step 6), after sintering, the P-type silicon 6 is formed at the interface of the aluminum paste and the P-type silicon substrate 3, and the silver paste is burnt through the back passivation layer 5 and is in contact with the back N-type silicon 4.

By adopting the embodiment, on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.

According to the crystalline silicon solar cell structure provided by the invention, the P-type silicon substrate 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 substrate 3, and the front N-type silicon 2 is connected with the P-type silicon substrate 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 of the P-type silicon substrate 3 is back surface N-type silicon 4 with higher phosphorus doping concentration, and the back surface N-type silicon 4 is connected with the P-type silicon substrate 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 provided with open grooves, the open grooves are open holes, the first metal electrode 7 penetrates through the open holes and is in ohmic contact with the P-type silicon 6, the first metal electrode 7 is 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 second metal electrode 8 penetrates through the passivation layer 5, the second metal electrode 8 is in ohmic contact with the back N-type silicon 4, and the second metal electrode 8 is 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 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 preparation method of a crystalline silicon solar cell, which comprises the following steps:

1) texturing is carried out on the surface of the P-type silicon substrate 3, the back surface of the P-type silicon substrate 3 is polished, and the front surface of the P-type silicon substrate 3 is a textured surface, and the back surface of the P-type silicon substrate 3 is a flat structure.

2) P type silicon substrate 3 double-sided phosphorus diffusion, form the higher N type silicon of phosphorus doping concentration on the front and back two sides of P type silicon substrate 3, there is phosphorus silicon glass that phosphorus diffusion forms on the surface of front N type silicon 2 and back N type silicon 4.

3) And removing the phosphorosilicate glass on the front surface of the P-type silicon substrate 3 by using hydrofluoric acid, reserving the phosphorosilicate glass on the back surface of the P-type silicon substrate 3, etching back the N-type silicon 2 on the front surface by using an alkali solution, reducing the phosphorus doping concentration of the N-type silicon 2 on the front surface, and protecting and reserving the N-type silicon 4 on the back surface by the phosphorosilicate glass on the back surface of the P-type silicon substrate 3.

4) And removing the phosphorosilicate glass on the back surface of the P-type silicon substrate 3 by using hydrofluoric acid, carrying out laser grooving on the back surface of the P-type silicon substrate 3, removing the N-type silicon 4 on the back surface of a grooving area, and forming a groove pattern into a grid line.

5) The front surface and the back surface of the P-type silicon substrate 3 are thermally oxidized to form a silicon oxide thin layer, the thickness of the silicon oxide thin layer is 1-10 nm, silicon nitride is deposited on the front surface and the back surface of the P-type silicon substrate 3 respectively by PECVD (plasma enhanced chemical vapor deposition), a front passivation layer 1 and a back passivation layer 5 are formed, and the front passivation layer 1 and the back passivation layer 5 are laminated layers of silicon oxide and silicon nitride.

6) Laser grooving is carried out on the back of the P-type silicon substrate 3, the grooving pattern and the grooving pattern in the step 4) are grid lines, the width of the grid lines is thinner, the back passivation layer 5 in the grooving area is removed, and the P-type silicon substrate 3 is exposed.

7) And (3) printing aluminum paste and silver paste on the back of the P-type silicon substrate 3, wherein the printed patterns are aluminum grid lines and silver grid lines, the aluminum grid lines are aligned to the laser grooving area in the step 6), after sintering, the P-type silicon 6 with high aluminum doping concentration is formed at the interface of the aluminum paste and the P-type silicon substrate 3, and the silver paste is burnt through the back passivation layer 5 and is contacted with the back N-type silicon 4.

The P-type silicon substrate 3 is preferably a P-type silicon wafer.

The invention adopts the floating junction as the passivation structure of the front surface, simplifies the preparation process on the one hand, avoids the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate on the other hand and improves the efficiency of the battery on the premise of ensuring the passivation effect of the front surface.

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

1) the floating junction is used as a passivation structure of the front surface, on the premise of ensuring the passivation effect of the front surface, on one hand, the preparation process is simplified, on the other hand, the influence of the high temperature of boron diffusion on the minority carrier lifetime of the P-type silicon substrate is avoided, and the efficiency of the battery is improved.

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

3) by back-etching the front N-type silicon, the phosphorus doping concentration of the front N-type silicon is reduced, and the passivation effect of the floating junction is improved.

An application of a preparation method of a crystalline silicon solar cell in 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.