KR101381844B1 - Method for menufacture the bifacial solar cell - Google Patents

Abstract

The present invention relates to a double-sided solar cell manufacturing method. Method for manufacturing a double-sided solar cell according to the present invention comprises the steps of (a) forming a texturing structure (110) on at least one surface of the front surface or the rear surface of the n-type silicon substrate 100; (b) forming a front emitter layer 200 on the front of the n-type silicon substrate 100; (c) forming a front passivation layer 300 on the front emitter layer 200; (d) forming a rear electric field layer 400 and a rear passivation and antireflection layer 500 on the back of the n-type silicon substrate 100; (e) forming a front anti-reflection layer 600 on the front passivation layer 300; And (f) forming a front electrode 700 on the front emitter layer 200, and forming a rear electrode 800 on the rear field layer 400, wherein step (d) includes: It is characterized by simultaneously forming the rear field layer 400 and the rear passivation and anti-reflection layer 500 through one diffusion process using the mixed solution.

Description

Method for manufacturing double-sided solar cell {METHOD FOR MENUFACTURE THE BIFACIAL SOLAR CELL}

The present invention relates to a double-sided solar cell manufacturing method. More specifically, the present invention relates to a double-sided solar cell manufacturing method capable of forming the rear electric field layer, the back passivation and the anti-reflection layer through one diffusion process.

Solar cell is a core element of solar power generation that converts sunlight into electricity, and its application range is very wide. Even when the photoelectric conversion efficiency is excellent, such a solar cell is limited to about 20%, and most of the remaining light is transmitted or reflected and is lost. In order to increase the efficiency of such a solar cell, it is very important to minimize the reflection of sunlight on the surface of the solar cell while maximizing the number of photons reaching the solar cell.

On the other hand, there are factors that determine the efficiency of the solar cell, such as the light receiving area of the solar cell, the resistance component inside the solar cell. One of the ways to maximize the light receiving area of the solar cell is a double-sided solar cell that can absorb the sunlight from the front and rear of the solar cell to perform photoelectric conversion.

For example, in a double-sided n-type solar cell, boron is implanted into the front surface as an impurity to form a front p + emitter layer, and phosphorus is diffused to the rear surface to form a back n + back surface field layer (BSF). ]. Thereafter, a passivation layer and an anti-reflection layer are formed on the front and rear surfaces to complete the manufacturing process.

In the conventional double-sided n-type solar cell as described above, the process of forming the rear electric field layer and the rear passivation layer is performed separately, and after forming the rear electric field layer and the rear passivation layer, the front anti-reflection layer is deposited and the substrate is again formed. Since the reverse anti-reflection layer must be deposited upside down, the process time is increased, and the cost for equipment for automating the process is increased.

Accordingly, an object of the present invention is to provide a double-sided solar cell manufacturing method that can be formed at the same time to solve the problems of the prior art as described above, the back field layer and the back passivation and anti-reflection layer.

In addition, an object of the present invention is to provide a double-sided solar cell manufacturing method that can reduce the back-side process time and process cost of the double-sided solar cell.

The above object of the present invention comprises the steps of (a) forming a texturing structure on at least one of a front surface or a back surface of an n-type silicon substrate; (b) forming a front emitter layer on the front of the n-type silicon substrate; (c) forming a front passivation layer on the front emitter layer; (d) forming a rear electric field layer, a rear passivation layer and an antireflection layer on a rear surface of the n-type silicon substrate; (e) forming a front anti-reflection layer on the front passivation layer; And (f) forming a front electrode on the front emitter layer, and forming a rear electrode on the rear electric field layer, wherein step (d) includes a single diffusion process using a predetermined liquid mixture. It is achieved by the method of manufacturing a double-sided solar cell, characterized in that to form the back surface layer and the back passivation and anti-reflection layer at the same time.

The predetermined mixed solution may be a mixture of a first source forming the rear field layer, a second source forming the rear passivation layer and an antireflection layer, and a solvent.

The first source may include n + impurities.

The n + impurities include N, P, As, Sb, Bi, P ₂ O ₅ , POCl ₃ , As (C ₂ H ₅ ) ₃ , As (CH ₃ ) ₃ , Bi (C ₆ H ₅ ) ₃ , Bi (CH ₃ ) ₃ or Bi (tmhd) ₃ .

The second source may be Al (OiC ₃ H ₇ ) ₃ , Al (OsC ₄ H ₉ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (hfac) ₃ , Al (CH ₃ ) ₃ , TMA: L (stabilized TMA), Al (CH ₃ ) ₂ H, Si (OC ₄ H ₉ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OCH ₃ ) ₄ , Si [N (CH ₃ ) ₂ ] ₄ , [(CH ₃ ) ₂ N] ₃ SiH, Ti {OCH (CH ₃ ) ₂ } ₄ , Ti (OCH ₂ CH ₃ ) ₄ Or Ti (OtC ₄ H ₉ ) ₄ It may include at least one.

The solvent may include at least one of DI water, (CH ₃ ) ₂ CHOH, C ₂ H ₅ OH, CH ₃ OH, CH ₃ COCH ₃ .

The predetermined liquid mixture may be applied to the rear surface of the n-type silicon substrate, and then heat-treated at a temperature of 600 ° C. or more and 1100 ° C. or less.

The front emitter layer may be formed by stacking a thin film layer including p + impurities on the entire surface of an n-type silicon substrate, or implanting p + impurities into the front surface of the n-type silicon substrate.

The p + impurity may include at least one of B, Al, Ga, In, and Tl.

In addition, the above object of the present invention is achieved by a double-sided solar cell manufactured using the double-sided solar cell manufacturing method.

According to the present invention, it is possible to provide a double-sided solar cell manufacturing method that can simultaneously form the rear electric field layer and the rear passivation and anti-reflection layer.

In addition, according to the present invention, it is possible to reduce the back side process time and the process cost of the double-sided solar cell.

In addition, according to the present invention, it is possible to simultaneously form the rear field layer, the rear passivation and the antireflection layer of the double-sided solar cell in a simplified manner.

1 to 5 are views sequentially showing a manufacturing process of a double-sided solar cell according to an embodiment of the present invention.
Figure 6 is a photograph showing the front and back of a double-sided solar cell manufactured according to an embodiment of the present invention.
7 is an enlarged photograph of a rear surface of a double-sided solar cell manufactured according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views, and length and area, thickness, and the like may be exaggerated for convenience.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

In the following detailed description, only some of the double-sided solar cells are illustrated in cross-section for convenience of description.

1 to 5 are views sequentially showing a manufacturing process of a double-sided solar cell according to an embodiment of the present invention.

Referring to FIG. 1, an n-type silicon substrate 100 is prepared. The n-type silicon substrate 100 may be manufactured by adding a group 15 element such as phosphorus and antimony to the silicon substrate as impurities.

Subsequently, a texturing structure may be formed on the surface of the n-type silicon substrate 100. In FIG. 1, the texturing structure is formed on both the front surface and the back surface of the n-type silicon substrate 100, but the texturing structure may be formed only on one surface of the n-type silicon substrate 100.

In the present invention, texturing is intended to prevent a phenomenon in which the characteristic is degraded due to optical loss of light incident on the n-type silicon substrate 100 surface of the double-sided solar cell. That is, by making the surface of the n-type silicon substrate 100 rough, it refers to forming the uneven pattern 110 on the surface of the n-type silicon substrate 100. For example, when the surface of the n-type silicon substrate 100 is roughened by texturing, light reflected once from the surface may be reflected back toward the double-sided solar cell, thereby reducing the loss of light and increasing the amount of light trapping. Thus, the photoelectric conversion efficiency of the double-sided solar cell can be improved. At this time, known texturing methods such as chemical etching, reactive ion etching (RIE) and sandblasting may be used as the texturing method.

Next, referring to FIG. 2, the front emitter layer 200 is formed on the entire surface of the n-type silicon substrate 100. The front emitter layer 200 may be formed by implanting p + impurities into the front surface of the n-type silicon substrate 100. The p + impurity preferably contains a Group 13 element such as B, Al, Ga, In, and Tl.

The method of forming the front emitter layer 200 may include physical vapor deposition (PVD) and low pressure chemical vapor deposition (PVD), such as thermal evaporation, e-beam evaporation, and sputtering. using chemical vapor deposition (CVD), such as chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), and metal organic chemical vapor deposition (MOCVD). A thin film layer containing p + impurities is formed by stacking on the entire surface of the n-type silicon substrate, or p + impurities are formed on the front surface of the n-type silicon substrate 100 by using a method such as diffusion and ion implantation. It may be formed by implanting in, but is not limited thereto, and a known impurity doping method may be used without limitation.

Next, referring to FIG. 3, the front passivation layer 300 is formed on the front emitter layer 200. The front passivation layer 300 serves to stabilize the solar cell by protecting the double-sided solar cell surface. The material of the front passivation layer 300 may be silicon oxide (SiO _x ) or silicon nitride (SiN _x ), but is not limited thereto. The front passivation layer 300 may be formed in the form of an oxidization / nitride passivation layer, for example, 3Si + 4HNO ₃ → 3SiO ₂ + 4NO + 2H ₂ O or 3SiH ₄ + 4NH ₃ → Si ₃ N ₄ + 12H _2. Can be. As the method for forming the front passivation layer 300, a low pressure chemical vapor deposition method, a plasma chemical vapor deposition method, or the like may be used.

Next, referring to FIG. 4, the rear electric field layer 400, the rear passivation, and the anti-reflection layer 500 may be simultaneously formed on the rear surface of the n-type silicon substrate 100. Specifically, the rear field layer 400 and the rear passivation and antireflection layer 500 may include a first source forming the rear field layer 400, a second source forming the rear passivation layer and the antireflection layer 500, and a solvent. It can form using the mixed liquid mixed.

Here, the first source should be understood as a source including n + impurities, that is, a material capable of high concentration doping of the back surface of the n-type silicon substrate 100 with n + to form the n + back surface field layer 400. For example, the n + impurities include group 15 elements such as N, P, As, Sb, Bi, P ₂ O ₅ (phosphorus pentoxide), POCl ₃ (phosphorus chloride), As (C ₂ H ₅ ) ₃ , As (CH ₃ ) at least one of ₃ , Bi (C ₆ H ₅ ) ₃ , Bi (CH ₃ ) ₃ or Bi (tmhd) ₃ .

The formation of the rear electric field layer 400 causes an internal potential difference in the solar cell due to high concentration doping, and prevents electrons from moving toward the rear electrode layer 400 in contact with the rear surface of the n-type silicon substrate, thereby reducing the recombination of electrons and holes. The voltage rises.

In addition, the second source is to protect the surface of the double-sided solar cell to stabilize the solar cell, the solar light incident on the solar cell is not absorbed by the photovoltaic device immediately reflected outside, thereby reducing the efficiency of the solar cell It should be understood as a source comprising a material forming the back passivation and antireflective layer 500 which serves to prevent. For example, the second source is a material capable of forming silicon oxide (SiO _x ), silicon nitride (SiN _x ), titanium oxide (TiO _x ), aluminum oxide (Al _x O _y ), and Al (OiC ₃ H). ₇ ) ₃ , Al (OsC ₄ H ₉ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (hfac) ₃ , Al (CH ₃ ) ₃ , TMA: L, Al (CH ₃ ) ₂ H, Si (OC ₄ H ₉ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OCH ₃ ) ₄ , Si [N (CH ₃ ) ₂ ] ₄ , [(CH ₃ ) ₂ N] ₃ SiH, Ti {OCH (CH ₃ ) ₂ } ₄ , Ti (OCH ₂ CH ₃ ) ₄ or Ti (OtC ₄ H ₉ ) ₄ .

In addition, the solvent is a solvent of the first source and the second source, and has a low surface tension to improve mutual wettability between the mixed liquid and the n-type silicon substrate 100 and to prevent organic substances from remaining in the mixed liquid. And it should be understood to include a material that serves to prevent the formation of natural oxide film. For example, the solvent may include at least one of DI water, (CH ₃ ) ₂ CHOH (isopropyl alcohol, IPA), C ₂ H ₅ OH (ethanol), CH ₃ OH (methanol), and CH ₃ COCH ₃ (acetone). It may include.

The mixed solution is applied to the rear surface of the n-type silicon substrate 100 and then heat-treated to diffuse the first source into the rear surface of the n-type silicon substrate 100 so that the n-type silicon substrate 100 is doped with n + high concentration to form a rear electric field layer ( 400) can be formed. It is preferable to perform heat processing at the temperature of 600 degreeC or more and 1100 degrees C or less.

When the back surface field layer 400 is formed, the second source, the atmosphere gas, and the n-type silicon substrate 100 react to form the back passivation and antireflection layer 500 of silicon oxide (SiO _x ) and silicon nitride (SiN _x ). , Titanium oxide (TiO _x ), aluminum oxide (Al _x O _y ) may be formed.

The coating of the mixed solution may be performed by dipping, painting, screen printing, doctor blade, roll printing, spray, dispensing, and the like. Known coating methods can be used without limitation.

Next, referring to FIG. 5, the front anti-reflection layer 600 may be formed on the front passivation layer 300. The material of the front anti-reflection layer 600 may be silicon oxide (SiO _x ) or silicon nitride (SiN _x ) similarly to the front passivation layer 300, but is not limited thereto. However, in order to effectively prevent reflection of sunlight by using light refraction, the front anti-reflection layer 600 may preferably use a material lower than the refractive index of the front passivation layer 300.

Subsequently, referring back to FIG. 5, the front electrode 700 may be formed on the front emitter layer 200, and the rear electrode 800 may be formed on the rear field layer 400.

As a method of forming the front electrode 700 and the rear electrode 800, various known electrode forming methods may be used. For example, metals such as silver (Ag), aluminum (Al), gold (Au), copper (Cu), zinc (Zn), titanium (Ti), and alloys thereof may be formed using screen printing. The metal paste may be coated on the front anti-reflection layer 600 and the rear passivation and anti-reflection layer 500, and then the metal paste may be sintered to form the front electrode 700 and the rear electrode 800. During sintering, the front anti-reflective layer 600, the front passivation layer 300, and the back passivation and anti-reflective layer 500, which are present underneath the areas where the metal paste is applied, can be removed, resulting in the front emitter layer 200 ) And the front electrode 700 are in contact with each other, and the rear electric field layer 400 and the rear electrode 800 are in contact with each other, thereby manufacturing a double-sided solar cell as illustrated in FIG. 5.

Figure 6 is a photograph showing the front and back of a double-sided solar cell manufactured according to an embodiment of the present invention.

Referring to Figure 6, it can be seen that the double-sided solar cell manufactured according to the manufacturing method of the present invention can receive sunlight from both the front and rear. In this case, the front anti-reflection layer 600 may be formed of silicon nitride, the rear passivation layer and the anti-reflection layer 500 may be formed of silicon oxide to represent different colors.

7 is an enlarged photograph of a rear surface of a double-sided solar cell manufactured according to another embodiment of the present invention.

Referring to FIG. 7, it can be seen that the double-sided solar cell manufactured according to the manufacturing method of the present invention has a back passivation and an antireflection layer formed on the back of the n-type silicon substrate.

As described above, according to the present invention, the back surface field layer 400 and the back passivation and anti-reflection layer 500 are performed by performing the back side process of the n-type silicon substrate 100 using the mixed solution of the first source, the second source, and the solvent. ) Can be formed at the same time. In addition, by simultaneously forming the rear electric field layer 400 and the rear passivation and anti-reflection layer 500 in a simplified manner using a mixed solution, the process of inverting the substrate and repeating the front and rear processes can be omitted. There is an advantage that can reduce the manufacturing time and manufacturing cost of the solar cell.

In the foregoing detailed description, the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and drawings are provided only to help a more general understanding of the present invention, and the present invention is limited to the above embodiments. However, one of ordinary skill in the art can make various modifications and variations from this description. Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

100: n-type silicon substrate
110: Texturing structure
200: front emitter layer
300: front passivation layer
400: rear electric layer
500: back passivation and antireflective layer
600: front antireflection layer
700: front electrode
800: Rear electrode

Claims (11)

(a) forming a texturing structure on at least one of a front surface or a back surface of the n-type silicon substrate;
(b) forming a front emitter layer on the front of the n-type silicon substrate;
(c) forming a front passivation layer on the front emitter layer;
(d) forming a rear electric field layer, a rear passivation layer and an antireflection layer on a rear surface of the n-type silicon substrate;
(e) forming a front anti-reflection layer on the front passivation layer; And
(f) forming a front electrode on the front emitter layer and forming a back electrode on the back field layer;
Including;
In the step (d), the rear field layer and the rear field layer are subjected to one diffusion process using a mixture of a first source for forming the rear field layer, a second source for forming the rear passivation layer and an antireflection layer, and a solvent. Double-sided solar cell manufacturing method characterized in that to form the back passivation and the anti-reflection layer at the same time. delete The method of claim 1,
The first source is a double-sided solar cell manufacturing method characterized in that it comprises n + impurities. The method of claim 3,
The n + impurities include N, P, As, Sb, Bi, P ₂ O ₅ , POCl ₃ , As (C ₂ H ₅ ) ₃ , As (CH ₃ ) ₃ , Bi (C ₆ H ₅ ) ₃ , Bi (CH ₃ ) A double-sided solar cell manufacturing method comprising at least one of ₃ or Bi (tmhd) ₃ . The method of claim 1,
The second source is a double-sided solar cell manufacturing method characterized in that it comprises a material capable of forming the back passivation and the anti-reflection layer. 6. The method of claim 5,
The material capable of forming the back passivation and the anti-reflection layer is Al (OiC ₃ H ₇ ) ₃ , Al (OsC ₄ H ₉ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (hfac) ₃ , Al (CH ₃ ) ₃ , TMA: L, Al (CH ₃ ) ₂ H, Si (OC ₄ H ₉ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OCH ₃ ) ₄ , Si [N (CH ₃ ) ₂ ] ₄ , [(CH ₃ ) ₂ N] ₃ SiH, Ti {OCH (CH ₃ ) ₂ } ₄ , Ti (OCH ₂ CH ₃ ) ₄ or Ti (OtC ₄ H ₉ ) ₄ Double sided solar cell manufacturing method. The method of claim 1,
Said solvent is at least one of DI water, (CH ₃ ) ₂ CHOH, C ₂ H ₅ OH, CH ₃ OH, CH ₃ COCH ₃ manufacturing method of a double-sided solar cell. The method of claim 1,
After applying the mixed solution to the back surface of the n-type silicon substrate, heat treatment at a temperature of 600 ℃ 1100 ℃ or less, characterized in that the double-sided solar cell manufacturing method. The method of claim 1,
The front emitter layer may be formed by stacking a thin film layer including p + impurities on the front surface of an n-type silicon substrate, or by injecting p + impurities into the front surface of an n-type silicon substrate. Way. 10. The method of claim 9,
The p + impurity is a double-sided solar cell manufacturing method characterized in that it comprises at least one of B, Al, Ga, In, Tl. A double-sided solar cell manufactured using the manufacturing method of any one of claims 1, 3 to 10.

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