CN110265497B

CN110265497B - A selective emitter n-type crystalline silicon solar cell and preparation method thereof

Info

Publication number: CN110265497B
Application number: CN201910578323.1A
Authority: CN
Inventors: 刘成法; 袁玲; 张然然; 朱权; 陈达明; 陈奕峰
Original assignee: Trina Solar Co Ltd
Current assignee: Trina Solar Co Ltd; Trina Solar Changzhou Science and Technology Co Ltd
Priority date: 2019-06-28
Filing date: 2019-06-28
Publication date: 2021-05-18
Anticipated expiration: 2039-06-28
Also published as: CN110265497A

Abstract

The invention discloses an n-type crystalline silicon solar cell with a selective emitter and a preparation method thereof. The method comprises: depositing a layer of boron-rich doping source on a specific pattern area of a silicon wafer; The wafer is advanced and diffused at high temperature; the borosilicate glass layer on the back of the silicon wafer is removed on one side, while the borosilicate glass layer on the front is retained; the boron emitter on the back and edge of the silicon wafer is removed and retextured; phosphorus diffusion on the back of the silicon wafer , and form a selective back field; clean and remove the front borosilicate glass layer and the back phosphorus silicate glass layer, deposit an aluminum oxide silicon nitride anti-reflection passivation film on the front, and deposit a silicon nitride passivation film on the back; screen printing the front electrode and back electrode. The invention can realize the selective boron emitter by one-step diffusion without the need of another boron source, greatly reduce the recombination of the metal contact area, increase the open-circuit voltage of the solar cell, improve the short-wave response of the battery, and increase the short-circuit current, thereby effectively Improve the photoelectric conversion efficiency of solar cells.

Description

N-type crystalline silicon solar cell with selective emitter and preparation method thereof

Technical Field

The invention belongs to the technical field of photovoltaics, and particularly relates to an n-type crystalline silicon solar cell with a selective emitter and a preparation method thereof.

Background

The constant pursuit of higher photoelectric conversion efficiency and lower manufacturing costs is the subject of the photovoltaic industry. At present, p-type crystalline silicon solar cells occupy the absolute share of the crystalline silicon market, but n-type crystalline silicon wafers have the advantages of long minority carrier lifetime, no light-induced attenuation, and the like compared with conventional p-type crystalline silicon wafers, and have higher-end efficiency improvement space. The prepared n-type crystalline silicon solar cell and the prepared n-type crystalline silicon solar cell module have the advantages of good weak light response, low temperature coefficient and higher reliability. With the more and more obvious efficiency advantage of the n-type crystalline silicon solar cell, the market share of the n-type crystalline silicon solar cell will be further improved.

One of the cores of the preparation method of the n-type crystalline silicon solar cell is the preparation of a boron emitter, a BBR3 liquid source diffusion method is generally adopted in the market at present, the boron emitter prepared by the method has the problems of difficult control of sheet resistance uniformity and high recombination of a metal electrode contact area, so that the open-circuit voltage of the cell is low, the filling factor is poor, the improvement of the efficiency of the n-type crystalline silicon solar cell is greatly limited, and the boron emitter is difficult to form a selective emitter by utilizing an etching or laser doping method commonly used in the p-type crystalline silicon solar cell.

Disclosure of Invention

In order to solve the above problems, the invention provides a method for preparing an n-type crystalline silicon solar cell with a selective emitter, which improves the efficiency of the n-type solar cell.

The technical scheme of the invention is as follows: a preparation method of an n-type crystalline silicon solar cell with a selective emitter comprises the following steps:

s1, selecting an n-type silicon wafer for pretreatment and texturing;

s2, depositing a layer of boron-rich doping source in the specific pattern area of the silicon wafer;

s3, carrying out high-temperature propulsion and diffusion on the silicon wafer on which the boron source is deposited;

s4, removing the borosilicate glass layer on the back side of the silicon wafer from one side, and simultaneously keeping the borosilicate glass layer on the front side to be used as a mask blocking layer in the next procedure to protect the p-n junction on the front side;

s5, removing the boron emitter on the back and the edge of the silicon wafer, and texturing again;

s6, diffusing phosphorus on the back of the silicon wafer, and forming a selective back field;

s7, cleaning and removing the borosilicate glass layer on the front side and the phosphorosilicate glass layer on the back side, depositing an aluminum oxide silicon nitride antireflection passivation film on the front side, and depositing a silicon nitride passivation film on the back side;

and S8, screen printing a front electrode and a back electrode, wherein the front electrode is printed in the heavily doped region, and the battery preparation is completed after high-temperature sintering.

The pretreatment and the texturing adopt the conventional cleaning and texturing processes; in addition, when high-temperature propelling and diffusing are carried out, the silicon wafer deposited with the boron source is placed into a tubular or chain type diffusion furnace for high-temperature propelling and diffusing; according to the invention, the borosilicate glass layer on the back side is removed on one side, and the borosilicate glass layer on the front side is retained, so that the borosilicate glass layer can be used as a mask blocking layer in a subsequent process to protect a p-n junction on the front side.

According to the invention, a layer of patterned boron-rich doping source is pre-deposited on the surface of a silicon wafer, and a selective emitter structure with a heavily doped patterned region and a lightly doped non-patterned region is formed by one-step diffusion in a mode of diffusing boron into a space at a high temperature, so that the composition of a metal contact region can be greatly reduced, the open-circuit voltage of a solar cell is improved, the short-wave response of the cell is improved, the short-circuit current is improved, and the photoelectric conversion efficiency of the solar cell is effectively improved. Meanwhile, the method is relatively simple in process and suitable for large-scale production.

Preferably, in the step S2, the specific pattern area is consistent with the front side metallization pattern, and the specific pattern area has a width of 20-1000 um.

Preferably, in step S5, the boron emitter on the back and the edge is removed by an alkali solution or an acid solution.

Preferably, the alkali liquor is TMAH or KOH.

Preferably, the acid solution is HF or HNO₃。

Preferably, in step S6, a selective back field is formed by etching or laser doping.

The invention also provides the high-efficiency passivated contact crystalline silicon solar cell prepared by the preparation method.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention can pre-deposit the patterned boron-rich doping source on the surface of the silicon wafer by screen printing, spin coating or spray coating and the like, and forms the selective emitter by one-step high-temperature diffusion by utilizing the diffusion of boron to the space at high temperature.

(2) According to the invention, the heavily doped region is formed in the high-temperature diffusion process of the pattern region deposited with the doping source, and the recombination of the metallized electrode in the region is greatly reduced, so that the open-circuit voltage of the solar cell is effectively improved.

(3) The non-pattern area without the deposited doping source forms a light doping area in high-temperature diffusion, the doping concentration is low, the short-wave correspondence is better, and the short-circuit current of the battery is higher.

(4) According to the invention, no boron source is needed for high-temperature diffusion, so that the use of the boron source can be effectively reduced, the process requirement on diffusion equipment is lowered, and the equipment cost is reduced.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

Example 1

A method for preparing an n-type crystalline silicon solar cell with a selective emitter is shown in FIG. 1, and comprises the following steps:

an n-type single crystal silicon is used as a silicon substrate, and conventional cleaning and texturing are performed first.

And then, depositing a layer of patterned boron-rich doping source on the front surface of the silicon substrate by adopting a screen printing mode.

Then the mixture is diffused in a tubular high-temperature diffusion furnace in the atmosphere of nitrogen and oxygen. And forming a p + + emitter with high doping concentration in the patterned region, forming a p + emitter with low doping concentration in the non-patterned region, and generating a borosilicate glass oxide layer with the doping concentration being more than 50nm in an oxygen atmosphere.

And removing the borosilicate glass oxidation layer on the back side by using a single surface of a chain type cleaning machine, using the borosilicate glass oxidation layer on the front side as a mask, and performing a single-surface texturing process on the back side by using TMAH.

And then high-temperature phosphorus diffusion is carried out, a back field of an n + + layer is formed on the back surface, and an n +/n + + selective back field is formed by using a mask printing and HF/HNO3 etching method.

And then cleaning and removing the borosilicate glass oxide layer on the front side and the phosphorosilicate glass oxide layer on the back side, depositing an aluminum oxide and silicon nitride passivation antireflection film on the front side, and depositing a silicon nitride passivation film on the back side.

Finally, screen printing front and back electrodes, the front electrode printed in the heavily doped region of the front and the back electrode printed in the n + + region of the selective back field. And (5) after high-temperature sintering, completing the preparation of the battery.

Claims

1. the preparation method of the n-type crystalline silicon solar cell of a selective emitter, is characterized in that, comprises the following steps:

S1. Select n-type silicon wafer pretreatment and texturing;

S2, depositing a layer of boron-rich doping source on a specific pattern area of the silicon wafer;

S3. Propelling and diffusing the silicon wafer after the boron source is deposited at high temperature;

S4, remove the borosilicate glass layer on the back side of the silicon wafer on one side, while retaining the borosilicate glass layer on the front side as a mask barrier layer for the subsequent process to protect the p-n junction on the front side;

S5. Remove the boron emitters on the back and edges of the silicon wafer, and retexture;

S6. Phosphorus diffuses on the back of the silicon wafer and forms a selective back field;

S7, cleaning and removing the borosilicate glass layer on the front side and the phosphorous silicate glass layer on the back side, depositing an aluminum oxide silicon nitride anti-reflection passivation film on the front side, and depositing a silicon nitride passivation film on the back side;

S8, screen printing the front electrode and the back electrode, wherein the front electrode is printed on the heavily doped area, and the battery is prepared after high temperature sintering.

2 . The method for preparing an n-type crystalline silicon solar cell with a selective emitter according to claim 1 , wherein in the step S2 , the specific pattern area is consistent with the front metallization pattern, and the specific pattern area has a width of 20˜20 . 1000um.

3 . The method for preparing an n-type crystalline silicon solar cell with a selective emitter as claimed in claim 1 , wherein in the step S5 , the boron emitters on the backside and the edge are removed by alkaline solution or acid solution. 4 .

4 . The method for preparing an n-type crystalline silicon solar cell with a selective emitter as claimed in claim 3 , wherein the alkaline solution is TMAH or KOH. 5 .

5 . The method for preparing an n-type crystalline silicon solar cell with a selective emitter according to claim 3 , wherein the acid solution is HF or HNO ₃ . 6 .

6 . The method for preparing an n-type crystalline silicon solar cell with a selective emitter according to claim 1 , wherein the selective back field is formed by etching or laser doping in the step S6 . 7 .

7 . The n-type crystalline silicon solar cell with selective emitter prepared by the preparation method according to any one of claims 1 to 6 .