阅读说明：本技术 一种太阳能电池硼硅玻璃钝化方法 (Method for passivating borosilicate glass of solar cell ) 是由 张双玉 张满满 乐雄英 陆祥 于 2021-07-22 设计创作，主要内容包括：本发明公开一种太阳能电池硼硅玻璃钝化方法,S1、对太阳能电池片进行表面处理,形成有效的绒面结构；S2、通过热扩散工艺,在形成绒面结构的所述太阳能电池片上生成一层厚度为80-120nm的硼硅玻璃层；S3、使用低浓度的氢氟酸腐蚀掉部分所述的硼硅玻璃层,保留厚度为10-25nm的硼硅玻璃层,即完成钝化。本发明的钝化方法保留了厚度为10-25nm的硼硅玻璃介质层,这层介质层会有类似于氧化硅的钝化作用,能够很好地提高电池片的效率；常规N型电池在完全去除硼硅玻璃层后,通常采用热氧或湿氧方式,在正面生成一层氧化硅钝化层,本发明的钝化方法取消了这一步骤,直接用扩散形成的硼硅玻璃层进行钝化,在减少工艺步骤的同时,确保电池品的效率,也降低的电池制作成本。(The invention discloses a method for passivating borosilicate glass of a solar cell, and S1, surface treatment is carried out on a solar cell to form an effective suede structure; s2, generating a borosilicate glass layer with the thickness of 80-120nm on the solar cell sheet with the textured structure through a thermal diffusion process; and S3, etching off part of the borosilicate glass layer by using low-concentration hydrofluoric acid, and reserving the borosilicate glass layer with the thickness of 10-25nm to finish passivation. The passivation method provided by the invention reserves a borosilicate glass dielectric layer with the thickness of 10-25nm, and the dielectric layer has a passivation effect similar to silicon oxide, so that the efficiency of the cell can be well improved; after the borosilicate glass layer of the conventional N-type battery is completely removed, a silicon oxide passivation layer is generated on the front surface of the conventional N-type battery usually in a hot oxygen or wet oxygen mode.)

1. A method for passivating borosilicate glass of a solar cell is characterized by comprising the following steps:

s1, carrying out surface treatment on the solar cell to form an effective suede structure;

s2, generating a borosilicate glass layer with the thickness of 80-120nm on the solar cell sheet with the textured structure through a thermal diffusion process;

and S3, etching off part of the borosilicate glass layer by using low-concentration hydrofluoric acid, and reserving the borosilicate glass layer with the thickness of 10-25nm to finish passivation.

2. The method of claim 1, wherein the surface treatment in step S1 includes removing various organic substances, damaged layers, and impurities from the surface of the solar cell by an alkali etching process to form an effective textured structure.

3. The method of claim 1, wherein the thermal diffusion process of step S2 comprises the following steps:

s2-1, cleaning the solar cell with the textured structure;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace pipe to 800 ℃, stabilizing for a period of time, and introducing oxygen in the stabilizing process;

s2-4, continuing to heat up the thermal diffusion furnace tube, heating up to 810 and 880 ℃, starting to introduce the boron source, and depositing for 20-30 minutes;

s2-5, continuing to heat the thermal diffusion furnace tube, keeping the temperature stable for 60-80 minutes after the temperature is raised to 880-1050 ℃, and introducing oxygen in the process of keeping the temperature stable;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen in the cooling process, and generating a borosilicate glass layer with the thickness of 80-120nm on the surface of the solar cell.

4. The method for passivating borosilicate glass of a solar cell according to claim 3, wherein in step S2-1, the solar cell with the textured structure is cleaned with deionized water or absolute ethyl alcohol.

5. The method for passivating borosilicate glass of a solar cell according to claim 3, wherein in step S2-3, the temperature of the thermal diffusion furnace tube is raised to 800 ℃ and stabilized for 3-5 minutes, and 10-15slm of oxygen is introduced during the stabilization process.

6. The method as claimed in claim 3, wherein the step S2-4 is performed by further heating the thermal diffusion furnace tube to a temperature of 810-880 ℃ and introducing a boron source of 100-300 sccm.

7. The method for passivating borosilicate glass of a solar cell according to claim 3, wherein 10 to 15slm of oxygen is introduced during the constant temperature stabilization in step S2-5.

8. The method as claimed in claim 3, wherein in step S2-6, oxygen of 100 and 500sccm is introduced during the temperature reduction process.

9. The method for passivating borosilicate glass for a solar cell according to claim 1, wherein the concentration of hydrofluoric acid in step S3 is 1-5 wt%; the corrosion time is 5-10 minutes.

Technical Field

The invention relates to the technical field of solar cells, in particular to a method for passivating borosilicate glass of a solar cell; the solar cell according to the present invention is mainly an N-type cell.

Background

As shown in fig. 1, in the manufacturing process of an N-type solar cell, boron source diffusion needs to be performed on one surface of a cell sheet 1 to form a P/N junction 2 in a core region of the cell, and during the process of forming the P/N junction by diffusion, a layer of borosilicate glass 3 with a certain thickness grows on the surface of the silicon wafer; however, the borosilicate glass 3 is mainly a boron-rich silicon dioxide layer, and the impurity content is high, which affects the cell efficiency, and in order to ensure the overall quality of the cell, the borosilicate glass 3 is generally corroded and disposed.

After removing the borosilicate glass layer, a conventional N-type cell usually adopts a thermal oxidation (or wet oxidation) mode to generate a silicon oxide passivation layer on the front surface, and passivates the solar cell so as to improve the efficiency of the cell; however, the conventional passivation method by hot oxygen or wet oxygen has the problems of complicated process steps and high cost, and is not suitable for mass production. Therefore, it is desirable to develop a new method for passivation of solar cells, which can reduce the cost while maintaining the efficiency of the cell.

Disclosure of Invention

Based on the problems that the existing solar cell adopts a hot oxygen or wet oxygen passivation mode, the process is complex, the process cost is high, and the method is not suitable for mass production, the invention provides a novel method for passivating borosilicate glass of the solar cell.

The invention is realized by the following technical scheme:

a method for passivating borosilicate glass of a solar cell is characterized by comprising the following steps:

s1, carrying out surface treatment on the solar cell to form an effective suede structure;

s2, generating a borosilicate glass layer with the thickness of 80-120nm on the solar cell sheet with the textured structure through a thermal diffusion process;

and S3, etching off part of the borosilicate glass layer by using low-concentration hydrofluoric acid, and reserving the borosilicate glass layer with the thickness of 10-25nm to finish passivation.

Specifically, a layer of borosilicate glass can be generated on the silicon surface of the N-type solar cell in the process of growing the P/N junction, and the thickness of the generated borosilicate glass layer is controlled to be 80-120nm of a boron-containing silicon oxide dielectric layer by controlling a thermal diffusion process; and then corroding part of the borosilicate glass by hydrofluoric acid, and reserving a boron-containing silicon dioxide dielectric layer with the thickness of 10-25nm, wherein the dielectric layer has a passivation effect similar to silicon oxide, and the efficiency of the cell can be well improved.

Further, the surface treatment in step S1 includes removing various organic substances, damaged layers, and impurities on the surface of the solar cell by an alkali etching process to form an effective textured structure. Specifically, the alkali etching may be performed by dissolving sodium hydroxide solution or potassium hydroxide.

A method for passivating borosilicate glass of a solar cell, wherein the thermal diffusion process in step S2 comprises the following steps:

s2-1, cleaning the solar cell with the textured structure;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace pipe to 800 ℃, stabilizing for a period of time, and introducing oxygen in the stabilizing process;

s2-4, continuing to heat up the thermal diffusion furnace tube, heating up to 810 and 880 ℃, starting to introduce the boron source, and depositing for 20-30 minutes;

s2-5, continuing to heat the thermal diffusion furnace tube, keeping the temperature stable for 60-80 minutes after the temperature is raised to 880-1050 ℃, and introducing oxygen in the process of keeping the temperature stable;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen in the cooling process, and generating a borosilicate glass layer with the thickness of 80-120nm on the surface of the solar cell.

Further, step S2-1, cleaning the solar cell with the textured structure with deionized water or absolute ethyl alcohol.

Further, step S2-3, heating the thermal diffusion furnace tube to 800 ℃ and stabilizing for 3-5 minutes, and introducing 10-15slm of oxygen in the stabilizing process. Specifically, slm is a unit of gas flow, and represents liters per minute under standard conditions (0 ℃, 1 atm).

Further, in step S2-4, the temperature of the thermal diffusion furnace is continuously raised to 810-. Specifically, sccm also refers to the unit of flow of gas, and represents the standard state (0 ℃, 1atm) ml per minute.

Further, step S2-5, introducing 10-15slm of oxygen in the constant temperature stabilizing process.

Further, in step S2-6, 100-.

Further, step S3, the concentration of the hydrofluoric acid is 1-5 wt%; the corrosion time is 5-10 minutes. Preferably, the hydrofluoric acid is etched for 5 to 10 minutes, and the generated borosilicate glass with the thickness of 80 to 120nm can be completely removed easily due to too long etching time, so that the passivation effect of the method can not be achieved; too short an etch time may result in a remaining borosilicate glass layer that is too thick to form an effective passivation.

The passivation method has the beneficial effects that:

(1) the conventional passivation method of the N-type solar cell is to completely remove the borosilicate glass layer and then generate a silicon oxide passivation layer on the front surface of the cell by adopting a hot oxygen or wet oxygen mode to complete the passivation of the cell product, however, the passivation mode has complex process and higher cost; the invention develops a novel solar cell passivation method based on the defects, the method directly cancels the step of completely removing the borosilicate glass layer in the traditional passivation mode, and the borosilicate glass layer formed by thermal diffusion is directly used for passivation, but the thickness of the borosilicate glass layer is strictly controlled within the range of 10-25nm, and the excessively thick or thin borosilicate glass layer is not beneficial to the improvement of the efficiency of a cell product, namely the passivation effect of the cell is not obvious.

(2) The thickness of the borosilicate glass layer (namely the boron-containing silicon dioxide dielectric layer) reserved by the passivation method is 10-25nm, and the dielectric layer has a passivation effect similar to silicon oxide, so that the efficiency of the cell can be well improved; after the borosilicate glass layer of the conventional N-type battery is completely removed, a silicon oxide passivation layer is generated on the front surface in a hot oxygen (or wet oxygen) mode.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a structural view of a solar cell.

In the figure: 1 battery piece, 2P/N junction, 3 borosilicate glass layers.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. 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.

Example 1

A method for passivating borosilicate glass of a solar cell comprises the following steps:

s1, performing surface treatment on the solar cell by adopting an alkali etching process, removing various organic matters, damaged layers and impurities on the surface of the solar cell, and forming an effective suede structure (sodium hydroxide or potassium hydroxide solution can be adopted for alkali etching);

s2, generating a borosilicate glass layer with the thickness of 120nm on the solar cell sheet with the textured structure by controlling a thermal diffusion process;

s3, and then etching off a part of the borosilicate glass layer using hydrofluoric acid having a concentration of 3.8 wt%, leaving the borosilicate glass layer with a thickness of 15nm, i.e., completing the passivation, wherein the time of hydrofluoric acid etching in this step is 8 minutes. The passivated solar cell of example 1 was designated as BSG-15 nm.

Preferably, the thermal diffusion process in step S2 in embodiment 1 includes the following steps:

s2-1, cleaning the solar cell with the textured structure with deionized water;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace tube to 800 ℃, stabilizing for 5 minutes, and introducing 15slm oxygen in the stabilizing process;

s2-4, continuing to heat the thermal diffusion furnace tube, heating to 850 ℃, introducing a boron source of 200sccm, and depositing for 25 minutes;

s2-5, continuously heating the thermal diffusion furnace tube to 1050 ℃, then keeping the temperature stable for 70 minutes, and introducing 15slm oxygen in the process of keeping the temperature stable; the time taken for raising the furnace temperature from 850 ℃ to 1050 ℃ in the step S2-4 is 10 minutes;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen of 300sccm in the cooling process, and generating a 120 nm-thick borosilicate glass layer on the surface of the solar cell.

Example 2

A method for passivating borosilicate glass of a solar cell comprises the following steps:

s1, performing surface treatment on the solar cell by adopting an alkali etching process, removing various organic matters, damaged layers and impurities on the surface of the solar cell, and forming an effective suede structure (sodium hydroxide or potassium hydroxide solution can be adopted for alkali etching);

s2, generating a borosilicate glass layer with the thickness of 80nm on the solar cell sheet with the textured structure by controlling a thermal diffusion process;

s3, and then etching off a part of the borosilicate glass layer using hydrofluoric acid having a concentration of 3.8 wt%, leaving the borosilicate glass layer having a thickness of 10nm, i.e., completing the passivation, wherein the time of hydrofluoric acid etching in this step is 10 minutes. The passivated solar cell of example 2 was designated as BSG-10 nm.

Preferably, the thermal diffusion process in step S2 in embodiment 2 includes the following steps:

s2-1, cleaning the solar cell with the textured structure with absolute ethyl alcohol;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace tube to 800 ℃, stabilizing for 3 minutes, and introducing 12slm oxygen in the stabilizing process;

s2-4, continuing to heat the thermal diffusion furnace tube, heating to 820 ℃, introducing a boron source of 200sccm, and depositing for 20 minutes;

s2-5, continuously heating the thermal diffusion furnace tube, keeping the temperature stable for 60 minutes after heating to 880 ℃, and introducing 15slm oxygen in the process of keeping the temperature stable; the time spent for raising the furnace temperature 820 ℃ to 880 ℃ in the step S2-4 is 10 minutes;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing 500sccm oxygen in the cooling process, and generating a borosilicate glass layer with the thickness of 80nm on the surface of the solar cell.

Example 3

A method for passivating borosilicate glass of a solar cell comprises the following steps:

s1, performing surface treatment on the solar cell by adopting an alkali etching process, removing various organic matters, damaged layers and impurities on the surface of the solar cell, and forming an effective suede structure (sodium hydroxide or potassium hydroxide solution can be adopted for alkali etching);

s2, generating a borosilicate glass layer with the thickness of 100nm on the solar cell sheet with the textured structure by controlling a thermal diffusion process;

s3, and then etching away a part of the borosilicate glass layer using hydrofluoric acid having a concentration of 3.8 wt%, leaving the borosilicate glass layer with a thickness of 25nm, i.e., completing the passivation, wherein the time of hydrofluoric acid etching in this step is 5 minutes. The passivated solar cell of example 3 was designated BSG-25 nm.

Preferably, the thermal diffusion process in step S2 in embodiment 3 includes the following steps:

s2-1, cleaning the solar cell with the textured structure with absolute ethyl alcohol;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace tube to 800 ℃, stabilizing for 3 minutes, and introducing 10slm oxygen in the stabilizing process;

s2-4, continuing to heat the thermal diffusion furnace tube, heating to 880 ℃, introducing a boron source of 200sccm, and depositing for 30 minutes;

s2-5, continuously heating the thermal diffusion furnace tube, keeping the temperature stable for 80 minutes after the temperature is raised to 1000 ℃, and introducing 10slm oxygen in the process of keeping the temperature stable; the time spent for raising the temperature of the furnace from 880 ℃ to 1000 ℃ in the step S2-4 is 10 minutes;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen of 300sccm in the cooling process, and generating a borosilicate glass layer with the thickness of 100nm on the surface of the solar cell.

Comparative example 1

A method for passivating borosilicate glass of a solar cell comprises the following steps:

s1, performing surface treatment on the solar cell by adopting an alkali etching process, removing various organic matters, damaged layers and impurities on the surface of the solar cell, and forming an effective suede structure (sodium hydroxide or potassium hydroxide solution can be adopted for alkali etching);

s2, generating a borosilicate glass layer with the thickness of 120nm on the solar cell sheet with the textured structure by controlling a thermal diffusion process;

s3, and then etching off part of the borosilicate glass layer by using hydrofluoric acid with the concentration of 3.8 wt% and reserving the borosilicate glass layer with the thickness of 8nm, namely completing passivation. The passivated solar cell of comparative example 1 was designated as BSG-8 nm.

Preferably, the thermal diffusion process in step S2 of comparative example 1 described above includes the steps of:

s2-1, cleaning the solar cell with the textured structure with deionized water;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace tube to 800 ℃, stabilizing for 5 minutes, and introducing 15slm oxygen in the stabilizing process;

s2-4, continuing to heat the thermal diffusion furnace tube, heating to 850 ℃, introducing a boron source of 200sccm, and depositing for 25 minutes;

s2-5, continuously heating the thermal diffusion furnace tube to 1050 ℃, then keeping the temperature stable for 70 minutes, and introducing 15slm oxygen in the process of keeping the temperature stable; the time taken for raising the furnace temperature from 850 ℃ to 1050 ℃ in the step S2-4 is 10 minutes;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen of 300sccm in the cooling process, and generating a 120 nm-thick borosilicate glass layer on the surface of the solar cell.

Comparative example 1 differs from example 1 in that the thickness of the borosilicate glass layer remaining after hydrofluoric acid etching at step S3 is different (i.e., example 1 remains 15nm and comparative example 1 remains 8nm), and the remaining conditions are the same.

Comparative example 2

A method for passivating borosilicate glass of a solar cell comprises the following steps:

s1, performing surface treatment on the solar cell by adopting an alkali etching process, removing various organic matters, damaged layers and impurities on the surface of the solar cell, and forming an effective suede structure (sodium hydroxide or potassium hydroxide solution can be adopted for alkali etching);

s2, generating a borosilicate glass layer with the thickness of 120nm on the solar cell sheet with the textured structure by controlling a thermal diffusion process;

s3, and then etching off part of the borosilicate glass layer by using hydrofluoric acid with the concentration of 3.8 wt% and reserving the borosilicate glass layer with the thickness of 30nm, namely completing passivation. The passivated solar cell of comparative example 2 was designated BSG-30 nm.

Preferably, the thermal diffusion process in step S2 of comparative example 2 described above includes the steps of:

s2-1, cleaning the solar cell with the textured structure with deionized water;

s2-2, after cleaning, placing the solar cell in a quartz boat, pushing the quartz boat into a thermal diffusion furnace tube, and closing a furnace door;

s2-3, heating the thermal diffusion furnace tube to 800 ℃, stabilizing for 5 minutes, and introducing 15slm oxygen in the stabilizing process;

s2-4, continuing to heat the thermal diffusion furnace tube, heating to 850 ℃, introducing a boron source of 200sccm, and depositing for 25 minutes;

s2-5, continuously heating the thermal diffusion furnace tube to 1050 ℃, then keeping the temperature stable for 70 minutes, and introducing 15slm oxygen in the process of keeping the temperature stable; the time taken for raising the furnace temperature from 850 ℃ to 1050 ℃ in the step S2-4 is 10 minutes;

and S2-6, starting to cool after the constant temperature is stable, continuously introducing oxygen of 300sccm in the cooling process, and generating a 120 nm-thick borosilicate glass layer on the surface of the solar cell.

The above comparative example 2 is different from example 1 in that the thickness of borosilicate glass remained after hydrofluoric acid etching at step S3 is different (example 1 remained 15nm, comparative example 2 remained 30nm), and the rest of the conditions are the same.

Comparative example 3

And completely removing the borosilicate glass layer formed by thermal diffusion in a conventional mode, and then passivating in a thermal oxidation mode.

And (3) testing: the performance of the passivated solar cells of examples 1-3 and comparative examples 1-3 was tested and the results are shown in table 1.

Table 1 shows the performance parameters of passivated solar cells of examples 1-3 and comparative examples 1-3

From the test data of examples 1-3 in table 1 above, it can be seen that the fill factor (FF%) after cell passivation is between 81.29-81.30 in the thickness range (10-25nm) of the borosilicate glass layer retained by the present invention, which is close to the fill factor data of comparative example 3 (thermal oxygen passivation) (81.37), indicating that the passivation method of the present invention can achieve almost the same efficiency as the conventional thermal oxygen passivation method, but the passivation method of the present invention has simpler process steps and lower cost compared with the conventional thermal oxygen passivation method, so the passivation method of the present invention has significant technical effects compared with the conventional thermal oxygen passivation method. The passivation method of the invention cancels the step of completely removing the borosilicate glass layer and forming a silicon oxide passivation layer by adopting thermal oxidation passivation; the method directly uses the borosilicate glass layer formed by diffusion to carry out passivation, thereby reducing the process steps, ensuring the efficiency of the battery product and reducing the manufacturing cost of the battery.

As can be seen from the test data of example 1 and comparative examples 1-2 in table 1 above, the fill factor of the passivated cell of comparative example 1 is 81.12, and the passivated fill factor of comparative example 2 is 80.89; it can be seen that the fill factor test data of comparative examples 1-2 is significantly different from the test data of example 1 (81.30), indicating that the performance of the passivated cells of comparative examples 1-2 differs greatly from that of example 1. The above test data thus shows that when the retained thickness of the borosilicate glass layer is too low or too high, it is not beneficial to passivate the cell, which affects the efficiency of the cell product.

The above-mentioned preferred embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention. Obvious variations or modifications of the present invention are within the scope of the present invention.