KR101223055B1 - Method of preparing solar cell and solar cell prepared by the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a solar cell and a solar cell manufactured using the same. The method of manufacturing a solar cell of the present invention includes (S1) forming a second conductive semiconductor layer on a first conductive semiconductor substrate; (S2) printing a back electrode forming paste in a predetermined pattern on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed; (S3) heat-treating the back electrode forming paste; (S4) forming an antireflection film on the second conductivity type semiconductor layer; (S5) printing the front electrode forming paste on the anti-reflection film in a predetermined pattern; And (S6) heat-treating the front electrode forming paste. According to the solar cell manufacturing method of the present invention, by forming an anti-reflection film or a passivation layer after the heat treatment to the back electrode, and then heat treatment to the front electrode, reducing the thermal burden applied to the anti-reflection film or the passivation layer to improve the performance of the solar cell You can.

Solar cell, photovoltaic effect, semiconductor, p-n junction, anti-reflection film, photoelectric conversion efficiency

Description

Method for manufacturing solar cell and solar cell manufactured using same {Method of preparing solar cell and solar cell prepared by the same}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a schematic diagram showing the basic structure of a solar cell.

2 is a view schematically showing the structure of a conventional general solar cell.

3 is a flowchart illustrating a conventional general solar cell manufacturing process.

4 is a process flowchart of the solar cell manufacturing method of the present invention.

The present invention relates to a method for manufacturing a solar cell and a solar cell manufactured using the same, and more particularly, to reduce the thermal burden caused by heat treatment on the anti-reflection film or the passivation layer, and to reduce the functional degradation due to the heat treatment. It relates to a solar cell manufacturing method and a solar cell produced thereby that can be improved.

Recently, as the prediction of depletion of existing energy sources such as oil and coal is increasing, interest in alternative energy to replace them is increasing. Among them, solar cells are particularly attracting attention because they are rich in energy resources and have no problems with environmental pollution. Solar cells include solar cells that generate steam for rotating turbines using solar heat, and solar cells that convert photons into electrical energy using the properties of semiconductors. Refers to photovoltaic cells (hereinafter referred to as solar cells).

Referring to FIG. 1 showing the basic structure of a solar cell, a solar cell has a junction structure of a p-type semiconductor 101 and an n-type semiconductor 102 like a diode, and when light is incident on the solar cell, Interaction with the materials that make up the semiconductor causes electrons with negative charge and electrons to escape, creating holes with positive charge, and as they move, current flows. This is called a photovoltaic effect. Among the p-type 101 and n-type semiconductors 102 constituting the solar cell, electrons are directed toward the n-type semiconductor 102 and holes are p-type semiconductors ( Pulled toward 101 and moved to the electrodes 103 and 104 bonded to the n-type semiconductor 101 and the p-type semiconductor 102, respectively, and when the electrodes 103 and 104 are connected by wires, electricity flows. Can get

The output characteristics of such a solar cell are generally evaluated by measuring an output current voltage curve using a solar simulator. The maximum output Pm is the point at which the product of output current Ip and output voltage Vp is maximized, Ip × Vp. The value obtained by dividing Pm by the total light energy incident on the solar cell (S × I: S is the device area and I is the intensity of light irradiated to the solar cell) is defined as the conversion efficiency η. To increase the conversion efficiency η, increase the short-circuit current Is (output current when V = 0 on the current voltage curve) or open voltage Voc (output voltage when I = 0 on the current voltage curve) or the square of the output current voltage curve. You should increase the fill factor (FF), which is close to. The closer the value of FF to 1, the closer the output current voltage curve is to the ideal square and the higher the conversion efficiency η. Mainly, Isc affects the absorption or reflectance of the light irradiated on the solar cell, Voc affects the degree of recombination of carriers (electrons and holes), and FF affects resistance in or between n-type and p-type semiconductors or between electrodes. Receive.

Recently, in order to improve the efficiency of a solar cell, it is common to form a passivation layer or an antireflection film on the front of the solar cell. The anti-reflection film is formed to lower the reflectance to sunlight to improve the short-circuit current value, and the passivation layer is formed to prevent the recombination of carriers to improve the open voltage.

However, the performance of the passivation layer and the anti-reflection film during the heat treatment for forming the front electrode and the back electrode performed at a high temperature during the manufacturing process of the solar cell is greatly reduced. Therefore, efforts to solve these problems have been made steadily in the related field, and the present invention has been devised under such technical background.

The present invention has been made to solve the above problems of the prior art, the technical problem to be achieved by the present invention is to improve the conventional solar cell manufacturing process to reduce the function degradation of the anti-freeze layer and anti-reflection film by heat treatment for electrode formation The purpose of the present invention is to provide a method for manufacturing a solar cell and a solar cell manufactured using the same, which are intended to improve the performance of a solar cell.

In order to achieve the technical problem to be achieved by the present invention, the present invention, (S1) forming a second conductive semiconductor layer on the first conductive semiconductor substrate; (S2) printing a back electrode forming paste in a predetermined pattern on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed; (S3) heat-treating the back electrode forming paste; (S4) forming an antireflection film on the second conductivity type semiconductor layer; (S5) printing the front electrode forming paste on the anti-reflection film in a predetermined pattern; And (S6) heat-treating the front electrode forming paste.

The present invention also provides a method for manufacturing a semiconductor device, the method comprising: (S1) forming a second conductive semiconductor layer on a first conductive semiconductor substrate; (S2) printing a back electrode forming paste in a predetermined pattern on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed; (S3) heat-treating the back electrode forming paste; (S4) forming a passivation layer on the second conductivity type semiconductor layer; (S4) forming an anti-reflection film on the passivation layer; (S5) printing the front electrode forming paste on the anti-reflection film in a predetermined pattern; And (S6) heat-treating the front electrode forming paste.

In the method of manufacturing the solar cell, the heat treatment temperature of the back electrode forming paste is preferably 800 ~ 920 ℃, the heat treatment temperature of the front electrode forming paste is preferably 730 ~ 800 ℃. In addition, the heat treatment time of the back electrode forming paste is preferably 5 to 30 seconds, and the heat treatment time of the front electrode forming paste is preferably 5 to 30 seconds. Preferably, the first conductive semiconductor substrate is a p-type silicon substrate, and the second conductive semiconductor layer is an n-type emitter layer, and the anti-reflection film and the passivation layer are typically made of silicon nitride.

The present invention provides a solar cell manufactured using the manufacturing method in addition to the manufacturing method of the solar cell.

Hereinafter, the present invention will be described in more detail with reference to the drawings. For better understanding, a look at the structure of a general solar cell and a conventional solar cell manufacturing method together.

2 is a view schematically showing the structure of a conventional general solar cell. Referring to FIG. 2, a solar cell is formed on a first conductivity type semiconductor substrate 201 and the first conductivity type semiconductor substrate 201 and has a conductivity type opposite to that of the first conductivity type semiconductor substrate 201. The pn structure, the passivation layer 205, and the reflection including a pn junction formed at the interface between the second conductive semiconductor layer 202 and the first conductive semiconductor substrate 201 and the second conductive semiconductor layer 202. The barrier layer 206, the front electrode 203, and the rear electrode 204 are included. The pn structure is a portion that receives sunlight and generates current by the photovoltaic effect, and the carriers generated therein are collected at the front electrode 203 and the rear electrode 204, and the front electrode 203 and the rear electrode 204 are formed. When the load is applied, the electricity generated by the solar cells can be used. The anti-reflection film 206 is configured to reduce reflectance of the solar cell, and the passivation layer 205 is configured to prevent carriers from recombining at the ends of the first conductive semiconductor substrate 201 and the second conductive semiconductor layer 202. do.

3 is a flowchart illustrating a conventional general solar cell manufacturing process. Referring to FIG. 3, first, a second conductive semiconductor layer is formed on a first conductive semiconductor substrate. Next, a passivation layer and / or an antireflection film are formed on the second conductivity type semiconductor layer. Next, the front electrode and the back electrode forming paste are printed according to a predetermined pattern to form the electrode, and then the front electrode is punched through to the second conductive semiconductor substrate, and the BSF is applied to the semiconductor substrate in contact with the back electrode. Heat treatment is performed to form a (Back Surface Field). The heat treatment temperature is about 800 ° C. The reason why the heat treatment temperature is about 800 ° C. is because both punch through and front surface field (BSF) formation of the front electrode can easily occur at the temperature. However, the heat treatment at such a temperature has a problem of deteriorating the performance of the antireflection film and the passivation layer.

Therefore, the present invention improves the conventional solar cell manufacturing process as described above, thereby reducing the thermal burden applied to the passivation layer and the anti-reflection film during the heat treatment for the formation of the front electrode and the rear electrode to prevent the functional degradation thereby.

That is, the present invention separates the front electrode and the back electrode manufacturing process, after forming the back electrode to form an anti-reflection film and / or passivation layer, and then to form the front electrode. The temperature required for punch-through of the front electrode is 730 ~ Since the temperature required for forming the BSF is 800 ° C. or higher, the thermal burden applied to the passivation layer and the anti-reflection film by the above process is greatly reduced.

Hereinafter, with reference to the process flow diagram of the solar cell manufacturing method of the present invention of Figure 4, look at the solar cell manufacturing method of the present invention in more detail for each step.

First, a second conductive semiconductor layer is formed on the first conductive semiconductor substrate. As the first conductive semiconductor substrate 201, a p-type silicon substrate doped with group III elements such as B, Ga, and In may be preferably used. For example, P, As, An n-type emitter layer doped with Group 5 elements such as Sb may be formed as the second conductive semiconductor layer 202. The n-type emitter layer may be formed by, for example, applying an n-type dopant to a p-type silicon substrate and then performing heat treatment to diffuse the n-type dopant into the p-type silicon substrate.

Next, a paste for forming a back electrode is printed on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed. Screen printing is typically used as a printing method. Aluminum is most preferable as the back electrode because the aluminum electrode not only has excellent conductivity but also has good affinity with silicon, so that it can be bonded well. In addition to the aluminum, the paste for forming the back electrode may be formed by further adding, for example, a binder and quartz silica. Examples of the binder may include terpineol.

After printing the back electrode forming paste, it is heat treated to form a BSF layer on the contact surface with the back electrode of the semiconductor substrate. At this time, the heat treatment temperature is preferably 800 ~ 920 ℃. If the upper limit of the heat treatment temperature range is exceeded, the characteristics of the aluminum BSF are rather deteriorated. If the lower limit is not reached, the aluminum BSF is not formed, which is not preferable. The heat treatment time is preferably 5 to 30 seconds, but when the upper limit is exceeded, bowing of the solar cell occurs due to thermal stress, and when the lower limit is reached, aluminum BSF is not formed, which is not preferable. .

When the back electrode is formed, an anti-reflection film is formed on the second conductive semiconductor layer. In addition, a passivation layer may be formed on the second conductivity type semiconductor layer, and an antireflection film may be formed on the passivation layer. In addition, two or more antireflection films may be configured to be stacked, or an antireflection film may be configured to simultaneously exhibit the function of the antifreeze layer without providing a separate antifreeze layer. The antireflection film and the passivation layer may be typically formed of silicon nitride, and chemical vapor deposition (CVD) or plasma chemical vapor deposition (PECVD) may be used.

Next, the front electrode forming paste is printed on the antireflection film according to a predetermined pattern. Screen printing is typically used as a printing method, and a silver electrode having excellent electrical conductivity is most preferably used as the front electrode. In addition to silver, for example, glass frit and a binder may be added to the front electrode forming paste.

After printing the front electrode forming paste, the front electrode is punched through to the second conductive semiconductor layer through heat treatment. At this time, it is preferable that heat processing temperature is 730-800 degreeC. When the upper limit of the heat treatment temperature range is exceeded, the glass frit component in the paste penetrates into the pn junction to reduce Voc and FF, and when the lower limit is reached, the punch through of the silver particles is difficult to be conducted. It is not preferable because the contact resistance between the type semiconductors increases and FF decreases. The heat treatment time is preferably 5 to 30 seconds. If the upper limit is exceeded, the glass frit component in the paste penetrates into the pn junction to reduce Voc and FF. If the lower limit is reached, the punch through of the silver particles is well achieved. It is not desirable because the FF is reduced so that it is not.

The solar cell manufactured using the solar cell manufacturing method of the present invention as described above has excellent thermal efficiency because the thermal burden applied to the passivation layer and the anti-reflection film during the manufacturing process is small and the performance deterioration thereof is less likely to occur.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1

An n + emitter layer was formed on the p-type single crystal silicon substrate, the back electrode was printed and heat treated, a passivation layer and an antireflection film were formed, and the solar cell was manufactured by printing and heat treated the front electrode.

In this case, a p-type silicon substrate (0.5-2Ω) of cz mono 125 × 125 cm ² was used as a semiconductor substrate, and an n + emitter layer was formed at 55Ω / sheet. The back electrode was formed by printing an aluminum electrode by screen printing and heat-treating at 800 ° C. for 10 seconds. The passivation layer (refractive index: 2.18, thickness: 20 nm) was formed of silicon nitride on the emitter layer using Direct High Frequency (13.56 MHz) PECVD, and the antireflection film (refractive index: 1.9, thickness: 70 nm) was used for direct high frequency (13.56). MHz) PECVD was used to form silicon nitride on the passivation layer. The deposition temperature of the passivation layer and the antireflection film was 350 ° C. The front electrode was formed by printing a silver electrode by screen printing and heat-treating at 750 ° C. for 10 seconds.

Photoelectric conversion efficiency measurement

The short circuit current (Jsc), the open circuit voltage (Voc), the FF and the photoelectric conversion efficiency of the solar cell according to Example 1 were measured using a solar simulator, and the measurement results are shown in Table 1 below. From the measurement results of Table 1, it can be seen that the solar cell of Example 1 manufactured according to the manufacturing method of the present invention exhibits excellent short circuit current, open voltage, and photoelectric conversion efficiency.

division Short circuit current (mA) Open-circuit voltage (V) FF (%) Photoelectric conversion efficiency (%) Example 1 31.9 0.619 77.7 15.3

The terms or words used in this specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors can appropriately define the concept of terms in order to best describe their invention. Based on the principle, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the exemplary embodiments described herein are only exemplary embodiments of the present invention and do not represent all of the technical ideas of the present invention, and various equivalents and modifications that may substitute them at the time of the present application may be used. It should be understood that there may be.

According to the solar cell manufacturing method of the present invention, by forming the anti-reflection film or the passivation layer after the heat treatment on the back electrode, and then heat treatment on the front electrode, reducing the thermal burden applied to the anti-reflection film or the passivation layer, thereby reducing the performance degradation By doing so, the performance of the solar cell can be improved.

Claims (10)

(S1) forming a second conductive semiconductor layer on the first conductive semiconductor substrate; (S2) printing a back electrode forming paste in a predetermined pattern on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed; (S3) heat-treating the back electrode forming paste; (S4) forming an anti-reflection film on the second conductive semiconductor layer after heat treating the back electrode forming paste; (S5) printing the front electrode forming paste on the anti-reflection film in a predetermined pattern; And (S6) heat-treating the front electrode forming paste; manufacturing method of a solar cell comprising a. (S1) forming a second conductive semiconductor layer on the first conductive semiconductor substrate; (S2) printing a back electrode forming paste in a predetermined pattern on a surface on which the second conductive semiconductor layer of the first conductive semiconductor substrate is not formed; (S3) heat-treating the back electrode forming paste; (S4) forming a passivation layer on the second conductive semiconductor layer after heat treating the back electrode forming paste; (S5) forming an anti-reflection film on the passivation layer; (S6) printing the front electrode forming paste on the anti-reflection film in a predetermined pattern; And (S7) heat-treating the front electrode forming paste; manufacturing method of a solar cell comprising a. The method according to claim 1 or 2, The heat treatment temperature of the back electrode forming paste is 800 ~ 920 ℃ manufacturing method of a solar cell. The method according to claim 1 or 2, The heat treatment temperature of the front electrode forming paste is 730 ~ 800 ℃ the manufacturing method of a solar cell. The method according to claim 1 or 2, The heat treatment time of the paste for forming the back electrode is a solar cell manufacturing method, characterized in that 5 ~ 30 seconds. The method according to claim 1 or 2, The heat treatment time of the front electrode forming paste is 5 ~ 30 seconds manufacturing method of a solar cell. The method according to claim 1 or 2, The first conductive semiconductor substrate is a p-type silicon substrate, the second conductive semiconductor layer is a manufacturing method of a solar cell, characterized in that the n-type emitter layer. The method according to claim 1 or 2, The anti-reflection film is a method of manufacturing a solar cell, characterized in that made of silicon nitride. 3. The method of claim 2, The passivation layer is a method of manufacturing a solar cell, characterized in that made of silicon nitride. delete

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