KR20120088029A - Solar cell and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a solar cell and a method of manufacturing the same.
One example of a solar cell according to the present invention includes a crystalline semiconductor substrate of a first conductivity type; An emitter portion having a second conductivity type opposite to the first conductivity type and forming a pn junction with the crystalline semiconductor substrate; An anti-reflective part positioned on the emitter part and including an optically conductive conductive material; A front electrode part positioned on the front surface of the crystalline semiconductor substrate and connected to the emitter part; And a rear electrode part positioned on the rear surface of the crystalline semiconductor substrate and connected to the crystalline semiconductor substrate.

Description

Solar cell and manufacturing method thereof

The present invention relates to a solar cell and a manufacturing method thereof.

Recently, as energy resources such as oil and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

Typical solar cells have a semiconductor portion that forms a p-n junction by different conductive types, such as p-type and n-type, and electrodes connected to semiconductor portions of different conductivity types, respectively.

When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductor unit, and the generated electron-hole pairs are separated into electrons and holes charged by a photovoltaic effect, and the electrons are n-type. Move toward the semiconductor portion, and holes move toward the p-type semiconductor portion. The moved electrons and holes are collected by different electrodes connected to the n-type and p-type semiconductor parts, respectively, and are obtained by connecting these electrodes with wires.

The present invention provides a solar cell in which the photoelectric efficiency is improved, and provides a method of manufacturing a solar cell in which the productivity is improved.

One example of a solar cell according to the present invention includes a crystalline semiconductor substrate of a first conductivity type; An emitter portion having a second conductivity type opposite to the first conductivity type and forming a p-n junction with the crystalline semiconductor substrate; An anti-reflective part positioned on the emitter part and including an optically conductive conductive material; A front electrode part positioned on the front surface of the crystalline semiconductor substrate and connected to the emitter part; And a rear electrode part positioned on the rear surface of the crystalline semiconductor substrate and connected to the crystalline semiconductor substrate.

Here, the anti-reflective unit may include a transparent conductive oxide (TCO) material.

Here, the thickness of the antireflection portion may be determined in a range of 10 μm or more and 100 μm or less.

In addition, the solar cell may further include a front protective part including a silicon oxide film (SiO 2) between the emitter part and the anti-reflection part.

Here, the front protection part may be formed by a method of forming a thermal oxide.

In addition, the thickness of the front protective part may be determined in a range of 10 nm or more and 50 nm or less.

Here, the front electrode part may be formed inside the hole to be connected to the emitter part after the hole is formed in the front protection part and the anti-reflection part, and may include silver (Ag).

In addition, an example of the solar cell manufacturing method according to the present invention is a step of forming a pn junction with the crystalline semiconductor substrate by forming an emitter portion of the second conductivity type opposite to the first conductivity type on the front surface of the crystalline semiconductor substrate of the first conductivity type ; Forming a front protective part including a silicon oxide film (SiO 2) on the aviator part by using a method of forming a thermal oxide; And forming a rear electrode portion on the rear surface of the crystalline semiconductor substrate.

The forming of the emitter part may include forming impurities of a second conductivity type on the entire surface of the crystalline semiconductor substrate; And heat treating an impurity of the second conductivity type to form an emitter portion.

In the forming of the front protection part, oxygen (O 2) gas may be injected during the heat treatment process for forming the emitter part to simultaneously form the front protection part including the silicon oxide layer (SiO 2) on the aviator part.

In addition, the manufacturing method of the solar cell may further include forming an anti-reflection portion including a light-transmitting conductive material on the front protective portion.

In addition, the method of manufacturing a solar cell may further include forming a hole in the anti-reflection portion and the front surface protection portion.

Here, the hole may be formed using a laser.

In addition, the method of manufacturing a solar cell may further include forming a front electrode part made of a conductive material in the hole to be connected to the emitter part after the hole is formed in the anti-reflection part and the front protection part.

One example of the solar cell according to the present invention improves the photoelectric efficiency, one example of the solar cell manufacturing method according to the invention has the effect that the productivity is further improved.

1 is a partial perspective view of a solar cell according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the solar cell shown in FIG. 1 taken along line II-II.
3A-3G illustrate an example of a method of manufacturing the solar cell shown in FIGS. 1 and 2.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. On the contrary, when a part is "just above" another part, there is no other part in the middle. Further, when a certain portion is formed as "whole" on another portion, it means not only that it is formed on the entire surface of the other portion but also that it is not formed on the edge portion.

Next, a solar cell according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a partial perspective view of a solar cell according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the solar cell illustrated in FIG. 1 taken along line II-II.

1 and 2, a solar cell 1 according to an exemplary embodiment of the present invention has an incident surface that is a surface of a substrate 110 and a substrate 110 on which light is incident (hereinafter, referred to as a 'front surface'). 'Emitter region (emitter) 121, the front protection portion 125 located on the emitter portion 120, the anti-reflection portion 130 located on the front protection portion 125, the emitter portion ( The front surface of the front electrode 140 connected to the 120, the back surface is located on the surface of the substrate 110 (hereinafter referred to as the 'back surface') that is opposite to the incident surface without light incident field (BSF) portion (BSF region) 171, and a rear electrode portion 150 positioned on the rear surface of the substrate 110.

The crystalline semiconductor substrate 110 is a semiconductor substrate having a first conductivity type, for example a p-type conductivity type, and made of single crystal silicon. When the substrate 110 has a p-type conductivity type, impurities of trivalent elements such as boron (B), gallium, indium, and the like are doped into the substrate 110. However, alternatively, the substrate 110 may be of n-type conductivity type. When the substrate 110 has an n-type conductivity type, impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb) may be doped into the substrate 110.

The front surface of this substrate 110 is textured to have a textured surface that is an uneven surface. For convenience, in FIG. 1, only the edge portion of the substrate 110 is shown as the texturing surface, and the anti-reflection portion 130 positioned thereon also shows only the edge portion as the uneven surface. However, substantially the entire front surface of the substrate 110 has a texturing surface, and thus the anti-reflection portion 130 located on the front surface of the substrate 110 also has an uneven surface.

In this case, the texturing surface is mainly formed using an alkaline solution, and the plurality of irregularities have irregular widths and heights. At this time, the width and height of each irregularities formed may be several tens of micrometers.

By the texturing surface having a plurality of irregularities, the light incident toward the front surface of the substrate 110 is generated by a plurality of reflection operations caused by the plurality of irregularities formed on the surface of the anti-reflection portion 130 and the substrate 110. It is incident inside 110. As a result, the amount of light reflected from the front surface of the substrate 110 decreases, thereby increasing the amount of light incident into the substrate 110. In addition, due to the texturing surface, the surface area of the substrate 110 and the anti-reflection portion 130 to which light is incident increases, thereby increasing the amount of light incident on the substrate 110.

The emitter part 120 is a region in which impurities of a second conductivity type, for example, an n-type conductivity type, which is opposite to the conductivity type of the substrate 110 are doped into the substrate 110, and a surface on which light is incident, that is, It is located inside the front surface of the substrate 110. Accordingly, the emitter portion 120 of the second conductivity type forms a p-n junction with the first conductivity type portion of the substrate 110.

In this case, since the emitter portion 120 is formed by diffusion of impurities into the substrate 110, the bonding surface of the substrate 110 and the emitter portion 120 is affected by the textured surface shape of the substrate 110, not the flat surface. Has uneven surface

However, the portion of the emitter portion 120 in contact with the front electrode portion 140 is cut by the laser during the process of forming the front electrode portion 140 during the manufacturing process, as shown in FIGS. The groove may be formed so that the curved surface is formed in the inner direction of the substrate 110 differently from the illustrated.

If the groove is formed so that the curved surface is formed in the inner direction of the substrate 110 in the part of the emitter portion 120 in contact with the front electrode portion 140, the area in contact with the front electrode portion 140 becomes wider. The current collecting efficiency of the front electrode 140 may be further improved.

Due to the built-in potential difference due to the pn junction between the substrate 110 and the emitter portion 120, the electron-hole pairs, which are charges generated by light incident on the substrate 110, are electrons and holes. Separately, electrons move toward n-type and holes move toward p-type. Therefore, when the substrate 110 is p-type and the emitter portion 120 is n-type, the separated holes move toward the rear surface of the substrate 110 and the separated electrons move toward the emitter portion 120.

The emitter portion 120 forms a pn junction with the substrate 110, that is, the first conductive portion of the substrate 110, and thus, unlike the present embodiment, when the substrate 110 has an n-type conductivity type, The terminator 120 has a p-type conductivity type. In this case, the separated electrons move toward the rear surface of the substrate 110 and the separated holes move toward the emitter portion 120.

When the emitter portion 120 has an n-type conductivity type, the emitter portion 120 may be formed by doping the substrate 110 with impurities of a pentavalent element, and conversely, when the emitter portion 120 has a p-type conductivity type, The dopant may be formed by doping the substrate 110 with impurities.

The front protection part 125 is positioned above the emitter part 120 and replaces defects such as dangling bonds, which are mainly present on and near the surface of the crystalline semiconductor substrate 110, into stable bonds. By performing a passivation function to reduce the disappearance of the charges transferred toward the surface of the crystalline semiconductor substrate 110 by the defect, the defects of the charge lost on or near the surface of the crystalline semiconductor substrate 110 by the defect Reduce the amount.

When the crystalline semiconductor substrate 110 has a texturing surface, the front protection part 125 may have a texturing surface having a plurality of irregularities similar to the substrate 110.

In general, since defects are mainly present on or near the surface of the crystalline semiconductor substrate 110, in the case of the embodiment, the front protection part 191 is directly in contact with the surface of the crystalline semiconductor substrate 110, thereby further improving the passivation function. As a result, the amount of charge loss further increases.

The front protection part 125 may be formed to include a silicon oxide film (SiO 2), and may be formed by a method of forming a thermal oxide film.

Here, a method of forming a thermal oxide film will be described in more detail.

First, the crystalline semiconductor substrate 110 is positioned inside a furnace, and then oxygen (O 2) gas is injected into the furnace during the heat treatment process of applying heat to the crystalline semiconductor substrate 110. (110) is exposed to oxygen (O2) gas.

In this case, the oxygen gas inside the furnace is separated into oxygen atoms, and these oxygen atoms combine with silicon atoms of the crystalline semiconductor substrate 110 at the initial stage of the heat treatment process to start forming a silicon oxide film (SiO 2). After the oxide film SiO2 is grown to about 500 kV, oxygen atoms no longer make integrated contact with the silicon atoms of the crystalline semiconductor substrate 110.

However, oxygen atoms remaining unreacted at this time enter the previously formed silicon oxide film SiO 2 and move until they come into contact with the silicon atoms of the crystalline semiconductor substrate 110, thereby growing the silicon oxide film SiO 2.

The silicon oxide film (SiO2) formed as described above is a form in which one silicon atom and two oxygen atoms are combined to have a very high purity. It will have a much improved passivation effect.

As such, the thickness t1 of the front surface protection part 125 including the silicon oxide film SiO2 is determined in a range of 10 nm to 50 nm.

Here, the thickness t1 of the front protective part 125 is set to 10 nm or more so that the silicon oxide film SiO2 performs a minimum passivation function, and the thickness t1 of the front protective part 125 is 50 nm. The reason for the following is to shorten the process time in consideration of the growth time of the silicon oxide film (SiO 2).

That is, as the thickness of the silicon oxide film SiO 2 increases, the passivation function is improved. However, the thickness of the silicon oxide film SiO 2 may be determined in a range of 10 nm or more and 50 nm or less in consideration of the slow growth time of the silicon oxide film SiO 2.

Next, the anti-reflection unit 130 is positioned above the front protection unit 125, mainly performs the anti-reflection function of light, and serves to prevent the passivation function of the front protection unit 125 located at the bottom thereof from decreasing. do.

The anti-reflection unit 130 includes a light transmissive conductive material. For example, the anti-reflection unit 130 may include a transparent conductive oxide (TCO) material, and examples of the TCO material may include indium tin oxide (ITO), indium zinc oxide (IZO), and zinc oxide (ZnO). have.

The TCO material included in the anti-reflection unit 130 is excellent in light transmittance, and has a much improved light transmission effect than silicon nitride (SiNx) used as an anti-reflection material.

More specifically, when the anti-reflective unit 130 is used as silicon nitride (SiNx), silicon nitride (SiNx) may reflect light but also absorb light due to its physical properties. Therefore, when silicon nitride (SiNx) is used as the anti-reflection portion 130, the amount of light absorbed by the crystalline semiconductor substrate 110 is relatively reduced.

However, when the TCO material is used as the anti-reflective unit 130 as in the present invention, the TCO material has much improved light transmittance than silicon nitride (SiNx). This is because the material properties of the TCO material do not absorb light and mainly reflect or transmit light.

Therefore, using the TCO material as the anti-reflection unit 130 will have a much improved light transmission effect than using the silicon nitride (SiNx).

The anti-reflection unit 130 may have a thickness t2 in a range of 10 μm or more and 100 μm or less. Here, the thickness t2 of the anti-reflection portion 130 is 10 μm or more for light reception optimization, and 100 μm or less is to reduce the manufacturing cost in consideration of the cost of the TCO material.

When the crystalline semiconductor substrate 110 has a texturing surface, the anti-reflection portion 130 may have a texturing surface having a plurality of irregularities similar to the substrate 110.

The front electrode part 140 is positioned on the front surface of the crystalline semiconductor substrate 110 and is connected to the emitter part 120 through the front protection part 125 and the anti-reflection part 130.

The front electrode unit 140 may be formed inside the hole to be connected to the emitter unit 120 after the hole is formed in the front protection unit 125 and the anti-reflection unit 130.

In this case, the front electrode part 140 may be more firmly connected to the emitter part 120, so that the contact resistance between the emitter part 120 and the front electrode part 140 may be further reduced to emitter part 120. There is an effect that can collect the charge collected from the more lossless.

The front electrode unit 140 includes a plurality of finger electrodes 141 and a plurality of front bus bars 142 connected to the plurality of finger electrodes 141.

The plurality of finger electrodes 141 are electrically and physically connected to the emitter unit 120 and are spaced apart from each other and extend side by side in a predetermined direction. The plurality of finger electrodes 141 collect electric charges, for example, electrons moved toward the emitter unit 120.

The plurality of front bus bars 142 are electrically and physically connected to the emitter unit 120 and extend side by side in a direction crossing the plurality of finger electrodes 141.

In this case, the plurality of front busbars 142 are positioned on the same layer as the plurality of finger electrodes 141 and are electrically and physically connected to the corresponding finger electrodes 141 at the point where they cross each finger electrode 141.

Accordingly, as shown in FIG. 1, the plurality of finger electrodes 141 have a stripe shape extending in the horizontal or vertical direction, and the plurality of front busbars 142 have a stripe shape extending in the vertical or horizontal direction. The front electrode 140 is positioned in a lattice shape on the entire surface of the substrate 110.

The plurality of front busbars 142 collects charges that are collected and moved by the plurality of finger electrodes 141 as well as charges that travel from the portion of the emitter portion 120 in contact.

Since each front busbar 142 must collect charges collected by a plurality of intersecting finger electrodes 141 and move them in a desired direction, the width of each front busbar 142 is greater than the width of each finger electrode 141. You can make it bigger.

The plurality of front bus bars 142 are connected to an external device and output the collected charges (eg, electrons) to the external device.

The plurality of finger electrodes 141 and the plurality of front bus bars 142 of the front electrode unit 140 are made of at least one conductive material such as silver (Ag).

In FIG. 1, the number of finger electrodes 141 and the front busbars 142 positioned on the substrate 110 is only one example, and may be changed in some cases.

The backside electric field 172 is a region in which impurities of the same conductivity type as the substrate 110 are doped at a higher concentration than the substrate 110, for example, a P + region.

A potential barrier is formed due to the difference in impurity concentration between the first conductive region and the rear conductive portion 172 of the substrate 110, thereby hindering the electron movement toward the rear conductive portion 172, which is the direction of the movement of the holes Thereby facilitating hole transport toward the rear electric field 172. Therefore, the amount of charge lost due to the recombination of electrons and holes in the rear surface and the vicinity of the substrate 110 is reduced and the movement of the desired charge (eg, holes) is accelerated to increase the amount of charge transfer to the rear electrode portion 150. .

The rear electrode unit 150 includes a rear electrode 151 and a plurality of rear bus bars 152 connected to the rear electrode 151. The rear electrode 151 is in contact with the rear electric field 172 located at the rear of the substrate 110, and substantially except for a portion where the rear edge of the substrate 110 and the rear bus bar 152 are positioned. 110) is located throughout the rear.

The rear electrode 151 contains a conductive material such as aluminum (Al).

The back electrode 151 collects charges, for example, holes, moving from the back field 172.

In this case, since the rear electrode 151 is in contact with the rear electric field 172 that maintains the impurity concentration higher than that of the substrate 110, the rear electrode 151 is in contact with the rear electric field 172 and the rear electrode 151. The resistance is reduced to improve the charge transfer efficiency from the substrate 110 to the back electrode 151.

The plurality of rear bus bars 152 are positioned on the rear surface of the substrate 110 where the rear electrode 151 is not located and are connected to the adjacent rear electrode 151.

In addition, the plurality of rear bus bars 152 may face the plurality of front bus bars 142 with respect to the substrate 110.

The plurality of rear busbars 152 collects charges transferred from the rear electrode 151, similar to the plurality of front busbars 142.

The plurality of rear busbars 152 are also connected to an external device, and the charges (eg, holes) collected by the plurality of rear busbars 152 are output to the external device.

The plurality of rear busbars 152 may be made of a material having better conductivity than the rear electrode 151, and contain at least one conductive material such as silver (Ag), for example.

In an alternative example, the back electrode 151 may be located throughout the back side of the substrate 110, in which case the plurality of back busbars 152 may include a plurality of front busbars 142 about the substrate 110. ) And are located on the rear electrode 151 to face each other. In this case, in some cases, the rear electrode 151 may be located on the entire rear surface of the rear surface except for the edge portion of the rear surface.

The operation of the solar cell 1 according to the present embodiment having such a structure is as follows.

When light is irradiated onto the solar cell 1 and incident on the emitter part 120, which is a semiconductor part, and the substrate 110 through the anti-reflection part 130, electron-hole pairs are generated in the semiconductor part by light energy. At this time, the reflection loss of the light incident on the substrate 110 by the texturing surface of the substrate 110 and the anti-reflection portion 130 is reduced, thereby increasing the amount of light incident on the substrate 110.

These electron-hole pairs are separated from each other by the pn junction of the substrate 110 and the emitter portion 120 so that the electrons and holes are, for example, the emitter portion 120 having the n-type conductivity type and the p-type conductivity. Respectively move toward the substrate 110 having the type. As such, the electrons moved toward the emitter unit 120 are collected by the plurality of finger electrodes 141 and the plurality of front busbars 142, move along the plurality of front busbars 142, and toward the substrate 110. The moved holes are collected by the adjacent rear electrode 151 and the plurality of rear busbars 152 and move along the plurality of rear busbars 152. When the front bus bar 142 and the rear bus bar 152 are connected with a conductive wire, a current flows, which is used as power from the outside.

Next, FIGS. 3A to 3G illustrate an example of a method of manufacturing the solar cell shown in FIGS. 1 and 2.

First, as illustrated in FIG. 3A, the front surface of the crystalline semiconductor substrate 110 having the first conductivity type is textured to form a plurality of protrusions on the front surface of the crystalline semiconductor substrate 110. To this end, the crystalline semiconductor substrate 110 may be cleaned before the texturing process to remove residues remaining on the surface of the crystalline semiconductor substrate 110 due to saw damage, and the texturing process may be performed.

The texturing treatment process may use a wet etching process, and after the wet etching process, a cleaning process of cleaning the surface of the crystalline semiconductor substrate 110 may be performed.

After the process of FIG. 3A, the emitter portion 120 of the second conductivity type opposite to the first conductivity type is formed on the entire surface of the crystalline semiconductor substrate 110 of the first conductivity type, and a method of forming a thermal oxide film is performed. The forming of the front protection part 125 including the silicon oxide film SiO2 is performed on the aviator part.

This step can be performed in two ways.

In the first method, as shown in FIG. 3B, first, an impurity 120 ′ of the second conductivity type is coated on the entire surface of the crystalline semiconductor substrate 110. In this case, when the impurity 120 ′ of the second conductivity type is formed on the entire surface of the crystalline semiconductor substrate 110, a spray method or a spin-on method may be used.

Thereafter, the crystalline semiconductor substrate 110 coated with the impurity of the second conductivity type is disposed in a furnace.

Thereafter, the furnace heat-treats the crystalline semiconductor substrate 110 coated with the impurity of the second conductivity type, so that the impurity 120 'of the second conductivity type is diffused into the front surface of the crystalline semiconductor substrate 110, and thus, FIG. As shown, the emitter portion 120 that forms the pn junction on the entire surface of the crystalline semiconductor substrate 110 can be formed.

As such, the oxygen (O 2) gas is injected into the furnace during the heat treatment process for forming the emitter part 120 in the furnace, and as shown in FIG. 3C, the silicon oxide film SiO 2 is included on the aviator part. Will be able to form the front protective portion 125 at the same time.

In the second method, first, as shown in FIG. 3B, a second conductive type impurity 120 ′ is coated on the entire surface of the crystalline semiconductor substrate 110 and then a heat treatment process is performed using a furnace. After the emitter part 120 is formed, the emitter part 120 is formed, and then oxygen (O 2) gas is injected into the furnace to form the front protection part 125 including the silicon oxide film (SiO 2) on the upper part of the aviator part. May be formed.

Comparing the first method with the second method, the first method is to simultaneously form the emitter portion 120 and the front protection portion 125 during the heat treatment process in the furnace, and the second method is to After the emitter part 120 is first formed by performing a heat treatment process, oxygen (O 2) gas is injected into the furnace to form the front protection part 125.

Both the first method and the second method are processes that can be continuously processed on one process line while the manufacturing process is performed along the process line, thereby improving productivity and process efficiency.

In addition, since the first method simultaneously forms the emitter portion 120 and the front protection portion 125 during the heat treatment process in the furnace, the process time is shorter than the second method.

As such, after the emitter unit 120 and the front protection unit 125 are formed, a rear electric field unit 172 and a rear electrode unit 150 may be formed on the rear surface of the crystalline semiconductor substrate 110 as shown in FIG. 3D. .

The rear electrode 151 of the rear electrode unit 150 may include a conductive material such as aluminum (Al), and the rear bus bar 152 may include a conductive material such as silver (Ag). have.

Here, the rear bus bar 152 includes a conductive material such as silver (Ag) is connected to the ribbon (ribbon) connecting the plurality of solar cells to each other on top of the rear bus bar 152, wherein the rear bus This is to reduce the contact resistance between the bar 152 and the ribbon (Ribbon) and to increase the bonding force.

In addition, the rear electric field unit 172 forms the rear electrode unit 150 including the rear electrode 151 and the rear bus bar 152 on the rear surface of the crystalline semiconductor substrate 110, and then performs a heat treatment process. It may be naturally formed on the rear surface of the crystalline semiconductor substrate 110 adjacent to the electrode 151. This is because impurities included in the rear electrode 151 naturally diffuse into the rear surface of the crystalline semiconductor substrate 110 during the heat treatment process.

In the heat treatment process, the furnace mentioned above may be used.

Next, as illustrated in FIG. 3E, an anti-reflective part 130 including a TCO material, which is a light-transmissive conductive material, may be formed on the front protection part 125.

The anti-reflection unit 130 may be formed in a range of 10 μm or more and 100 μm or less on the front protection part 125 using a sputtering method or a chemical vapor deposition (CVD) method.

Thereafter, as illustrated in FIG. 3F, a hole may be formed in the anti-reflective part 130 and the front protection part 125. As such, the hole may be formed by irradiating a laser.

Such a hole may be formed in the anti-reflection part 130 and the front protection part 125 along the pattern of the front electrode part 140 shown in FIG. 1.

Thereafter, as shown in FIG. 3G, after the holes are formed in the anti-reflection part 130 and the front protection part 125, the front electrode part 140, which is a conductive material, is formed inside the hole to be connected to the emitter part 120. It can be formed.

As such, the method of forming the front electrode 140, which is a conductive material, in the hole may use a screen printing method.

As such, after the anti-reflection portion 130 and the front electrode portion 140 are formed on the front surface of the crystalline semiconductor substrate 110, a low temperature heat treatment process may be performed to cure the front electrode portion 140. The low temperature heat treatment temperature here is much lower than that of the process of forming the emitter portion 120 or the process of forming the backside electric field portion 172, and becomes approximately 150 ° C to 250 ° C.

As described above, the low-temperature heat treatment process for curing the front electrode 140 is to prevent the physical properties of the anti-reflective unit 130 including the light transmissive conductive material from changing.

When the heat treatment temperature rises to about 300 ° C. or more, the TCO material included in the anti-reflective unit 130 may be denatured and the light transmittance may be impaired, resulting in a decrease in the efficiency of the anti-reflective unit 130. Because.

As described above, after forming a hole in the anti-reflection unit 130 and the front protection unit 125 using a laser, a method of forming the front electrode unit 140 using a screen printing method is described. The contact resistance between the front electrode part 140 and the emitter part 120 can be reduced, and the formation of the front electrode part 140 can be made easier, so that the productivity can be improved and the efficiency of the solar cell can be improved. It is.

That is, since it is not necessary to use a separate mask or alignment to form the front electrode part 140, the process time can be shortened to improve productivity, and the emitter part 120 is exposed in advance by using a laser. Since the front electrode 140 is in direct contact with the upper part of the emitter part 120, the contact between the front electrode part 140 and the emitter can be more stably and secured, thereby improving efficiency and productivity of the solar cell. It can be.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

1: solar cell 110: substrate
121: emitter portion 125: front protective portion
130: antireflection portion 140: front electrode portion
141: front electrode 142: front busbar
150: rear electrode portion 151: rear electrode
152: rear busbar 172: rear electric field

Claims (15)

A crystalline semiconductor substrate of a first conductivity type;
An emitter portion of a second conductivity type opposite to the first conductivity type and forming a pn junction with the crystalline semiconductor substrate;
An anti-reflective part positioned on the emitter part and including a light-transmitting conductive material;
A front electrode part positioned on a front surface of the crystalline semiconductor substrate and connected to the emitter part; And
A solar cell positioned on a rear surface of the crystalline semiconductor substrate and connected to the crystalline semiconductor substrate. The method of claim 1,
The anti-reflective unit includes a transparent conductive oxide (TCO) material. The method of claim 1,
The thickness of the anti-reflection portion is a solar cell, characterized in that determined in the range of 10um or more and 100um or less. The method of claim 1,
The solar cell
And a front protective part comprising a silicon oxide film (SiO 2) between the emitter part and the anti-reflective part. The method of claim 4, wherein
The front protection part is a solar cell, characterized in that formed by a method of forming a thermal oxide (Thermal Oxide). The method of claim 4, wherein
The thickness of the front protective portion is a solar cell, characterized in that determined in the range of 10nm or more and 50nm or less. The method of claim 4, wherein
And the front electrode part is formed inside the hole to be connected to the emitter part after the hole is formed in the front protective part and the anti-reflection part. The method of claim 1,
The front electrode unit is a solar cell, characterized in that containing silver (Ag). Forming an emitter portion of a second conductivity type opposite to the first conductivity type on a front surface of the crystalline semiconductor substrate of a first conductivity type to form a pn junction with the crystalline semiconductor substrate;
Forming a front protective part including a silicon oxide film (SiO 2) on the aviator part by using a method of forming a thermal oxide; And
Forming a rear electrode portion on the back of the crystalline semiconductor substrate. The method of claim 9,
Forming the emitter portion
Forming an impurity of the second conductivity type on an entire surface of the crystalline semiconductor substrate; And
And heat-treating the impurities of the second conductivity type to form an emitter portion. 11. The method of claim 10,
Forming the front protection portion
And injecting oxygen (O2) gas during the heat treatment process to form the emitter portion, thereby simultaneously forming a front protective portion including a silicon oxide film (SiO2) on the aviator portion. The method of claim 9,
The manufacturing method of the solar cell
And forming an anti-reflective part including a light-transmitting conductive material on the front protection part. The method of claim 12,
The manufacturing method of the solar cell
And forming a hole in the anti-reflection portion and the front surface protection portion. The method of claim 13,
The hole is a method of manufacturing a solar cell, characterized in that formed using a laser (laser). The method of claim 13,
The manufacturing method of the solar cell
And forming a front electrode part made of a conductive material in the hole so as to be connected to the emitter part after holes are formed in the anti-reflection part and the front protection part.

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