KR20180076197A - Solar cell and method for manufacturing the same - Google Patents

Abstract

According to an embodiment of the present invention, a method for manufacturing a solar cell includes a cutting step of manufacturing a plurality of unit solar cells by cutting a mother solar cell. The cutting step includes a laser processing step using a water jet laser. Accordingly, the present invention can simplify manufacturing processes and maximize the output of a solar cell panel.

Description

SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell and a manufacturing method thereof, and more particularly, to a solar cell having improved structure and manufacturing process and a manufacturing method thereof.

With the recent depletion of existing energy sources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells are attracting attention as a next-generation battery that converts solar energy into electric energy.

In such solar cells, various layers and electrodes can be fabricated by design. The solar cell efficiency can be determined by the design of these various layers and electrodes. In order to commercialize solar cells, it is required to overcome low efficiency, and various layers and electrodes are required to be designed and manufactured so as to maximize the efficiency of the solar cell.

The present invention provides a solar cell having excellent efficiency and being manufactured by a simple process and a method of manufacturing the solar cell.

A manufacturing method of a solar cell according to an embodiment of the present invention includes a cutting step of cutting a parent solar cell to produce a plurality of unit solar cells, and the cutting step includes a laser processing process using a water jet laser.

A solar cell according to an embodiment of the present invention includes: a semiconductor substrate including a side surface having a cut surface and an uncut surface; A conductive type region formed on the semiconductor substrate or on the semiconductor substrate; An electrode connected to the conductive region; An oxide layer formed on the cut surface; And an insulating film formed on the non-cut surface, wherein the thickness of the oxide layer is smaller than the thickness of the insulating film.

According to the present embodiment, the unit solar cell can be manufactured by cutting the solar cell while effectively preventing damage to the solar cell, including a laser processing process using a water jet laser, in the cutting process. At this time, since the oxide layer is formed on the cut surface during the laser machining process by the water jet laser, there is no need to add a process for passivating the cut surface separately. This makes it possible to simplify the manufacturing process and can be applied to solar cells of various structures.

The unit solar cell fabricated according to this method is applied to a solar cell panel to minimize the output loss of the solar cell panel, thereby maximizing the output. At this time, the oxide layer formed during the cutting process remains, so that the efficiency of the solar cell can be improved and the output of the solar cell panel can be improved by passivating the cut surface.

1 is a front plan view showing two unit solar cells formed by cutting one mother solar cell according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II in FIG.
3 is a front plan view showing four solar cells formed by cutting one parent solar cell according to a modification of the present invention.
4 is a schematic cross-sectional view of a solar cell panel including the unit solar cell shown in Fig.
5A and 5B are cross-sectional views illustrating a method of manufacturing a unit solar cell according to an embodiment of the present invention.
6A and 6B are cross-sectional views illustrating a method of manufacturing a unit solar cell according to another embodiment of the present invention.
7 is a cross-sectional view illustrating a unit solar cell according to another embodiment of the present invention.
8 is a cross-sectional view illustrating a unit solar cell according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it is needless to say that the present invention is not limited to these embodiments and can be modified into various forms.

In the drawings, the same reference numerals are used for the same or similar parts throughout the specification. In the drawings, the thickness, the width, and the like are enlarged or reduced in order to make the description more clear, and the thickness, width, etc. of the present invention are not limited to those shown in the drawings.

Wherever certain parts of the specification are referred to as "comprising ", the description does not exclude other parts and may include other parts, unless specifically stated otherwise. Also, when a portion of a layer, film, region, plate, or the like is referred to as being "on" another portion, it also includes the case where another portion is located in the middle as well as the other portion. When a portion of a layer, film, region, plate, or the like is referred to as being "directly on" another portion, it means that no other portion is located in the middle.

Hereinafter, a solar cell and a method of manufacturing the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a front plan view showing two unit solar cells formed by cutting one mother solar cell according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. 1 .

Referring to FIGS. 1 and 2, the parent solar cell 100a according to the present embodiment includes a plurality of unit solar cells 100 cut by a cutting line CL. When the parent solar cell 100a is cut along the cutting line CL, a plurality of unit solar cells 100 are manufactured. Each unit solar cell 100 thus manufactured functions as one solar cell.

In the drawings and the following description, for the sake of convenience, the cutting line CL is extended along the center of the parent solar cell 100a so that two unit solar cells 100 from one parent solar cell 100a . The active region AA in which the conductive type regions 20 and 30 and the first and second electrodes 42 and 44 are located corresponding to each unit solar cell 100 is located in the parent solar cell 100a , These active regions AA are spaced apart from each other with the isolation region 140 therebetween. The inactive region NAA in which the conductive type regions 20 and 30 and / or the first and second electrodes 42 and 44 are not located as a whole is located at the edge of each unit solar cell 100, and the inactive region The separation area 140 is located at the edge adjacent to the cut surface CL. In the isolation region 140, the conductive regions 20 and 30 and / or the first and second electrodes 42 and 44 may not have been formed since the parent solar cell 100a was manufactured, The conductive type regions 20 and 30 and / or the first and second electrodes 42 and 44 disappear in the vicinity of the cutting line CL or another layer (for example, the oxide layer 120) may be formed and the isolation region 140 may be formed.

However, the present invention is not limited thereto, and three or more unit solar cells 100 may be manufactured from one parent solar cell 100a by having two or more separation regions 140 or cutting lines CL.

The unit solar cell 100 in this embodiment includes a semiconductor substrate 10 including a base region 110 and conductive regions 20 and 30 formed on the semiconductor substrate 10 or on the semiconductor substrate 10. [ And electrodes 42, 44 connected to the conductive regions 20, 30. The conductive regions 20 and 30 may include a first conductive type region 20 and a second conductive type region 30 having different conductivity types and the electrodes 42 and 44 may include a first conductive type Type region 20 and a second electrode 44 connected to the second conductivity type region 30. The first electrode 42 and the second electrode 44 may be connected to each other. And further includes an oxide layer 120 and insulating films 22, 24, and 32 such as a first passivation film 22, an anti-reflection film 24, and a second passivation film 32. [

In this embodiment, since the unit solar cell 100 is manufactured by cutting, the side surface of the unit solar cell 100 is composed of the cut surface CS and the non-cut surface NCS. The oxide layer 120 is formed on the cut surface CS and the insulating layers 22, 24 and 32 are formed on the non-cut surface NCS. The oxide layer 120 is thinner than the insulating layers 22, 24 and 32 . This will be described in more detail later. The presence or absence of the oxide layer 120 or the insulating films 22, 24 and 32, the presence or absence of the first and second inclined sides 163a and 163b, , Surface roughness difference on the microscope, and surface morphology difference.

The semiconductor substrate 10 may include a base region 110 having a first or second conductivity type including a first or a second conductivity type dopant at a relatively low doping concentration. As an example, the base region 110 may have a second conductivity type. The base region 110 may be comprised of a single crystalline semiconductor (e.g., a single single crystal or polycrystalline semiconductor, such as single crystal or polycrystalline silicon, particularly monocrystalline silicon) comprising a first or second conductivity type dopant. The base region 110 having a high degree of crystallinity and having few defects or the unit solar cell 100 based on the semiconductor substrate 10 has excellent electrical characteristics.

An anti-reflection structure capable of minimizing reflection can be formed on the front surface and the rear surface of the semiconductor substrate 10. For example, a texturing structure having a concavo-convex shape in the form of a pyramid or the like may be provided as an antireflection structure. The texturing structure formed in the semiconductor substrate 10 may have a certain shape (e.g., a pyramid shape) having an outer surface formed along a specific crystal plane (e.g., (111) plane) of the semiconductor. If the surface roughness of the semiconductor substrate 10 is increased due to the unevenness formed on the front surface of the semiconductor substrate 10 by such texturing, the reflectance of light incident into the semiconductor substrate 10 can be reduced to minimize optical loss. However, the present invention is not limited thereto, and a texturing structure may be formed on only one side of the semiconductor substrate 10, or a texturing structure may not be formed on the front and back sides of the semiconductor substrate 10.

A first conductivity type region 20 having a first conductivity type may be formed on one side (e.g., a front side) of the semiconductor substrate 10. And a second conductive type region 30 having a second conductive type may be formed on the rear side of the semiconductor substrate 10. [ The first and second conductivity type regions 20 and 30 may have a different conductivity type than the base region 110 or may have a higher doping concentration than the base region 110 when the first and second conductivity type regions 20 and 30 have the same conductivity type as the base region 110 I have.

In this embodiment, the first and second conductivity type regions 20 and 30 may be formed as a doped region constituting a part of the semiconductor substrate 10. The first conductive type region 20 may be composed of a crystalline semiconductor (e.g., a single crystal or polycrystalline semiconductor, for example, single crystal or polycrystalline silicon, particularly monocrystalline silicon) including a first conductive type dopant. And the second conductivity type region 30 may be composed of a crystalline semiconductor (e.g., a single crystal or a polycrystalline semiconductor, for example, a single crystal or a polycrystalline silicon, particularly, a single crystal silicon) including a second conductive type dopant. As described above, when the first and second conductivity type regions 20 and 30 constitute a part of the semiconductor substrate 10, the junction characteristics with the base region 110 can be improved.

However, the present invention is not limited thereto, and at least one of the first and second conductivity type regions 20 and 30 may be formed separately from the semiconductor substrate 10 on the semiconductor substrate 10. In this case, a semiconductor layer (for example, an amorphous semiconductor layer, an amorphous semiconductor layer, or the like) having a crystal structure different from that of the semiconductor substrate 10 is formed so that the first or second conductivity type regions 20 and 30 can be easily formed on the semiconductor substrate 10, A microcrystalline semiconductor layer, or a polycrystalline semiconductor layer, for example, an amorphous silicon layer, a microcrystalline silicon layer, or a polycrystalline silicon layer).

One of the first and second conductivity type regions 20 and 30, which has a conductivity type different from that of the base region 110, constitutes at least a part of the emitter region. The emitter region forms a pn junction with the base region 110 to produce a carrier by photoelectric conversion. The other of the first and second conductivity type regions 20 and 30 having the same conductivity type as the base region 110 constitutes at least a part of a surface field region. The electric field region forms an electric field that prevents carriers from being lost by recombination on the surface of the semiconductor substrate 10. [ For example, in this embodiment, the base region 110 has the second conductivity type, the first conductivity type region 20 constitutes the emitter region, and the second conductivity type region 30 constitutes the rear electric field region can do. However, the present invention is not limited thereto.

In the drawing, the first conductive type region 20 is formed as a whole and has a homogeneous structure having a uniform doping concentration, and the second conductive type region 30 is formed only in the region where the second electrode 44 is located, As shown in FIG. By minimizing the area of the second conductivity type region 30 as described above, the short-circuit current (Jsc) and the open-circuit voltage can be improved by reducing the recombination. However, the present invention is not limited thereto. Thus, the first conductive type region 20 may be a uniform structure or a selective structure, and the second conductive type region 30 may have a uniform structure, an optional structure, or a local structure. The selective structure has a high doping concentration, a large junction depth, and a low resistance in a portion adjacent to the first or second electrode 42 or 44 in the first or second conductivity type region 20 or 30, Doping concentration, small junction depth, and high resistance.

The first or second conductivity type dopant may be n-type or p-type. As the p-type dopant, a group III element such as boron (B), aluminum (Al), gallium (Ga), or indium (In) can be used. In the case of the n-type, Group 5 elements such as phosphorus (P), arsenic (As), bismuth (Bi) and antimony (Sb) can be used. For example, the p-type dopant may be boron (B) and the n-type dopant may be phosphorus (P).

For example, in this embodiment, the base region 110 and the second conductivity type region 30 may have an n-type and the first conductivity type region 20 may have a p-type. Then, the base region 110 and the first conductivity type region 20 form a pn junction. When the pn junction is irradiated with light, electrons generated by the photoelectric effect move toward the rear surface of the semiconductor substrate 10 and are collected by the second electrode 44, and the holes move toward the front surface of the semiconductor substrate 10 1 electrode 42. In this case, Thereby, electric energy is generated. Then, holes having a slower moving speed than electrons may move to the front surface of the semiconductor substrate 10, rather than the rear surface thereof, thereby improving the efficiency. However, the present invention is not limited thereto, and it is also possible that the base region 110 and the second conductivity type region 30 have a p-type and the first conductivity type region 20 has an n-type.

The first passivation film 22 and / or the second passivation film 22 are formed on at least the front surface of the semiconductor substrate 10 (more precisely, on the first conductive type region 20 formed on the front surface of the semiconductor substrate 10) Barrier film 24 may be located. The second passivation film 32 as the second insulating film can be located at least on the rear surface of the semiconductor substrate 10 (more precisely on the second conductive type region 30 formed on the rear surface of the semiconductor substrate 10) have. The first passivation film 22 and the second passivation film 32 may be formed in contact with the semiconductor substrate 10 and / or the antireflection film 24 may be formed in contact with the first passivation film 22 . Then, the structure can be simplified. However, the present invention is not limited thereto.

The first passivation film 22 and the antireflection film 24 may be formed entirely on the front surface of the semiconductor substrate 10 except for the first opening 102. [ The second passivation film 32 may be formed entirely on the rear surface of the semiconductor substrate 10 except for the second opening 104. In the drawing, the first and second passivation films 22 and 32 and the antireflection film 24 are formed to extend to the side surface of the semiconductor substrate 10. According to this, the side surface of the semiconductor substrate 10 is also passivated, so that the passivation characteristic can be improved.

The first passivation film 22 or the second passivation film 32 is formed in contact with the semiconductor substrate 10 to passivate defects existing in the front surface or bulk of the semiconductor substrate 10. [ Accordingly, it is possible to increase the open-circuit voltage of the unit solar cell 100 by removing recombination sites of the minority carriers. The antireflection film 24 can reduce the reflectance of light incident on the front surface of the semiconductor substrate 10 and increase the amount of light reaching the pn junction. Accordingly, the short circuit current Isc of the unit solar cell 100 can be increased.

The first passivation film 22, the antireflection film 24, and the second passivation film 32 may be formed of various materials. In one example, the first passivation film 22, the anti-reflection film 24 or the passivation film 32 is a silicon nitride film, a silicon nitride film containing hydrogen, silicon oxide, silicon nitride oxide, aluminum oxide film, a silicon carbide film, MgF _2, ZnS , TiO _2, and CeO ₂ , or a multi-layer structure in which two or more films are combined.

For example, in the present embodiment, the first passivation film 22 and / or the antireflection film 24 and the second passivation film 32 may not have a dopant or the like so as to have excellent insulating properties, passivation properties, and the like . However, the present invention is not limited thereto.

The first electrode 42 is formed by filling at least a portion of the first opening 102 and is electrically connected to the first conductive region 20 2 opening portion 104 and is electrically connected to (e.g., formed in contact with) the second conductive type region 30. [0050] The first and second electrodes 42 and 44 are made of various conductive materials (for example, metal) and may have various shapes.

Referring to FIG. 1, the first electrode 42 may include a plurality of finger electrodes 42a spaced apart from each other with a predetermined pitch. Although the finger electrodes 42a are parallel to each other and parallel to the edge of the semiconductor substrate 10, the present invention is not limited thereto. The first electrode 42 may include a bus bar electrode 42b formed in a direction crossing (for example, orthogonal to) the finger electrodes 42a and connecting the finger electrodes 42a. Only one bus bar electrode 42b may be provided or a plurality of bus bar electrodes 42b may be provided with a larger pitch than the pitch of the finger electrodes 42a as shown in FIG. At this time, the width of the bus bar electrode 42b may be larger than the width of the finger electrode 42a, but the present invention is not limited thereto. Therefore, the width of the bus bar electrode 42b may be equal to or smaller than the width of the finger electrode 42a.

The finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may both be formed through the first passivation film 22 and the antireflection film 24 which are the first insulating film . That is, the first opening 102 may be formed corresponding to both the finger electrode 42a and the bus bar electrode 42b of the first electrode 42. [ However, the present invention is not limited thereto. As another example, a finger electrode 42a of the first electrode 42 may be formed through the first passivation film 22, and a bus bar electrode 42b may be formed on the first passivation film 22. In this case, the first opening 102 is formed in a shape corresponding to the finger electrode 42a, and may not be formed in a portion where only the bus bar electrode 42b is located.

The second electrode 44 may include a finger electrode and a bus bar electrode corresponding to the finger electrode 42a and the bus bar electrode 42b of the first electrode 42, respectively. The finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may be directly applied to the finger electrode and the bus bar electrode of the second electrode 44. [ The contents of the first passivation film 22 and the antireflection film 24 which are the first insulating film in the first electrode 42 are directly applied to the second passivation film 32 which is the second insulating film in the second electrode 44 . The width and pitch of the finger electrode 42a and the bus bar electrode 42b of the first electrode 42 may be the same as the width and pitch of the finger electrode and bus bar electrode of the second electrode 44 May be different.

However, the present invention is not limited thereto, and the first electrode 42 and the second electrode 44 may have different planar shapes, and various other modifications are possible.

As described above, in the present embodiment, the first and second electrodes 42 and 44 of the unit solar cell 100 have a certain pattern, and the unit solar cell 100 is optically coupled to the front and rear surfaces of the semiconductor substrate 10. [ And has a bi-facial structure capable of being incident. Thus, the amount of light used in the unit solar cell 100 can be increased to contribute to the improvement of the efficiency of the unit solar cell 100. However, the present invention is not limited thereto, and it is also possible that the second electrode 44 is formed entirely on the rear side of the semiconductor substrate 10. Various other variations are possible.

Here, as described above, the unit solar cell 100 is manufactured by cutting the parent solar cell 100a along the cutting line CL. When the parent solar cell 100a is divided into a plurality of unit solar cells 100, when a plurality of unit solar cells 100 are connected to form a solar cell panel 200 It is possible to reduce the output loss (cell to module loss, CTM loss).

More specifically, the output loss has a value obtained by multiplying the square of the current by the resistance of each solar cell, and the output loss of the solar cell panel including a plurality of solar cells is expressed by the square of the current of each solar cell The value multiplied by the resistance multiplied by the number of solar cells. However, there is a current generated by the solar cell area itself in the current of each solar cell. When the area of the solar cell is increased, the corresponding current is also increased, and when the area of the solar cell is decreased, the corresponding current is also decreased.

If the unit solar cells 100 are cut to form a plurality of unit solar cells 100 as in the present embodiment, the current is reduced in proportion to the area and the number of the unit solar cells 100 increases inversely do. For example, when one unit solar cell 100 manufactured from the parent solar cell 100a is provided with one cutting line CL, the current in each unit solar cell 100 is supplied to the parent solar cell 100a, And the number of unit solar cells 100 is twice that of the parent solar cell 100a. As described above, the current is reflected as a square value in the output loss, and the number is reflected as it is. Therefore, when the current is reduced to one half and the number is doubled, the output loss value is reduced to one half. Accordingly, when the solar cell panel 100 is manufactured by manufacturing a plurality of unit solar cells 100 by cutting the solar cell 100a as in the present embodiment, the output loss of the solar cell panel 200 .

In this embodiment, the conventional solar cell 100a is manufactured and then cut to cut the area of the unit solar cell 100. According to this, by using the existing equipment and thus the optimized design, The solar cell 100a may be manufactured and then cut. As a result, facility burden and process cost burden are minimized. On the other hand, if the size of the parent solar cell 100a is reduced, there is a burden of replacing the used equipment or changing the setting.

However, if the mother solar cell 100a is cut and then cut in the same manner as the conventional method, the cut surface CS existing in the unit solar cell 100 (a part of the side surface of the unit solar cell 100) 10 and / or the first and second conductivity type regions 20, 30 may be exposed as they are. If the semiconductor substrate 10 is exposed without being passivated, the efficiency of the unit solar cell 100 and the output of the solar cell panel including the unit cell 100 can be reduced by increasing the probability of surface recombination. For example, the efficiency of the unit solar cell 100 can be reduced to about 1% to 3%. Further, during the cutting process, The conductive type regions 20 and 30 and the semiconductor substrate 10 and / or the electrodes 42 and 44 are melted and unintentionally joined together to form a shunt pass, ) May not work. Or the metal material constituting the electrodes 42 and 44 may undesirably adhere to the exposed regions of the conductive regions 20 and 30 and / or the semiconductor substrate 10 to deteriorate performance, (100) may not operate. As a result, the efficiency of the unit solar cell 100 may be lowered or a failure may occur.

In consideration of this, in the present embodiment, the parent solar cell 100a is cut using a cutting process in which the oxide layer 120 can be formed on at least a part of the cut surface CS in the cutting step of cutting the parent solar cell 100a . If the oxide layer 120 is formed on at least a part of the cut surface CS of the semiconductor substrate 10 during the cutting process as described above, the cut surface CS can be effectively passivated without the additional step of forming the oxide layer 120 . The oxide layer 120 formed in the cutting process is formed of a compound of oxygen and a semiconductor material constituting the semiconductor substrate 10 because oxygen is reacted with the cut surface CS of the semiconductor substrate 10 from which the cutting process is exposed. In one example, in the case where the semiconductor substrate 10 includes silicon, the oxide layer 120 may be a silicon oxide layer. As described above, when the oxide layer 120 covering at least a part of the cut surface CS of each unit solar cell 100 is formed in the cutting process, it is possible to prevent or minimize the surface recombination that has conventionally occurred in the cut surface CS even in a simple process can do. Accordingly, the efficiency of the unit solar cell 100 can be improved and the output of the solar cell panel 200 including the same can be improved.

Generally, two solar cells 100a are fabricated from a substantially circular ingot of the semiconductor substrate 10 and have two axes orthogonal to each other (e.g., a finger electrode 42a Axis and the bus bar electrode 42b) are the same or substantially the same. For example, in this embodiment, the semiconductor substrate 10 of the parent solar cell 100a may have an octagonal shape having oblique sides 113a and 113b at four corner portions in an approximate square shape. With such a shape, the semiconductor substrate 10 having the widest area from the same ingot can be obtained. Thus, the parent solar cell 100a has a symmetrical shape, and has a maximum horizontal axis and a maximum vertical axis, and a minimum horizontal axis and a minimum vertical axis have the same distance.

In this embodiment, since the solar cell 100a is cut along the cutting line CL to form the unit solar cell 100, the shape of the semiconductor substrate 10 of the solar cell 100 having the long axis and the short axis .

In this embodiment, the oxide layer 120 may be formed so as to cover at least a part (for example, the entirety) of one side of the unit solar cell 100. This is because the cut line CL or the oxide layer 120 is formed across the two different edges of the semiconductor substrate 10 in the parent solar cell 100a. For example, in the parent solar cell 100a, the cut line CL or the oxide layer 120 may have a straight shape or a constant width in plan view. Thus, cutting can be performed stably while minimizing the area of the region cut by the cutting line CL. However, the present invention is not limited thereto, and the cutting line CL may have various shapes.

The plurality of unit solar cells 100 located within the parent solar cell 100a have such a shape that the cutting line CL extends along the first direction parallel to the finger electrodes 42a The active regions AA of the plurality of unit solar cells 100 extend along the first direction and extend in the second direction intersecting the first direction can do.

More specifically, the unit solar cell 100 includes first and second long sides 111a and 111b formed along the long axis or the first direction and parallel to each other, and first and second long sides 111a and 111b formed along the short axis or the second direction, And second short sides 112a and 112b. The semiconductor substrate 10 has a first inclined side 113a and a second long side 113b that are inclined with respect to the long axis and the short axis (or the first and second directions) and connect the first long side 111a and the first short side 112a. And a second inclined side 113b connecting the first short side 112a and the second short side 112b. The second long side 111b and the first short side 112a may be connected to each other and the second long side 111b and the second short side 112b may be connected to each other. However, the present invention is not limited to this, and the unit solar cell 100 or the semiconductor substrate 10 may have the first and second long sides 111a and 111b without the first and second inclined sides 113a and 113b, , And first and second short sides 112a and 112b. Various other variations are possible.

Here, the side surface located at least one of the long sides 111a and 111b corresponds to the cut surface CS. In this embodiment, the side located at the second long side 111b is a cut surface CS, and the remaining first long side 111a, the first short side 112a, and the second short side 112b, and the first and second inclined sides 113a, 113b are non-cut surfaces (NCS). At this time, as described above, the oxide layer 120 is formed on the cut surface CS in the cutting process. The first and / or second insulating films are formed to extend from the non-cut surface (NCS). Although the second passivation film 32, the first passivation film 22 and the antireflection film 24 are sequentially disposed (in order, for example, in contact with each other) in the non-cut surface NCS, ), The order of lamination, and the like can be variously modified.

As a result, the side surface of each unit solar cell 100 that cuts the parent solar cell 100a is passivated by the insulating films 22, 24, and 32 or the oxide layer 120. [ Accordingly, it is possible to improve the passivation characteristics to minimize the occurrence of damage, improve the efficiency of the unit solar cell 100, and improve the output of the solar cell panel 200 including the same.

At this time, since the oxide layer 120 formed on the cut surface CS is formed in a process different from the insulating films 22, 24, and 32 (or the oxide films included therein) formed on the non-cut surface NCS, , Width or thickness, laminated structure, etc.). Particularly, when the thickness (or width) T1 of the oxide layer 120 located on the cut surface CS is smaller than the thickness (or width) T1 of the insulating films 22, 24 and 32 (or the first passivation film 22, 2 passivation film 32), respectively. Since the oxide layer 120 is formed during the process of cutting along the cutting line CL without using a separate deposition process or the like, the oxide layer 120 is formed to be thinner than the insulating films 22, 24, and 32 manufactured using a separate deposition process or the like.

That is, the thickness T1 of the oxide layer 120 positioned on the side surface along the second long side 111b constituting the cut surface CS is greater than the thickness T1 of the first long side 111a, the first short side 111b, And the thickness of the insulating films 22, 24, and 32 located on the side surfaces along the first and second inclined sides 113a and 113b. For example, the thickness T1 of the oxide layer 120 may be less than 100 nm (e.g., 30 nm to 70 nm) and the thickness of the insulating films 22, 24, 32 or the thickness of the first passivation film 22 included therein, The antireflection film 24 and the second passivation film 32 may have a thickness of 100 nm or more (for example, 100 nm to 1 um, for example, 100 nm to 300 nm). Even if the oxide layer 120 is relatively thin as described above, the effect of passivation of the cut surface CS can be realized. The first passivation film 22, the antireflection film 24, and the second passivation film 32 are formed to a sufficient thickness by vapor deposition or the like so that the desired effect can be sufficiently realized while minimizing the time of the manufacturing process . However, the present invention is not limited thereto, and the thickness T1 of the oxide layer 120 and the thickness of the insulating films 22, 24 and 32 may have various values.

The insulating layer 22 may be formed of a plurality of layers and at least one of the insulating layers 22, 24, and 32 may be formed of a single layer, And may have a different material from the substrate 120. This is because the oxide layer 120 and the insulating films 22, 24, and 32 are separately formed in different processes.

The first long side 111a and the first and second short sides 112a and 112b and the first and second oblique sides 113a and 113b, which are the second long side 111b and the non-cut side NCS, The arrangement of at least one of the conductive type regions 20 and 30 and the electrodes 42 and 44 may be different from the other portions.

More specifically, in order to minimize the width of the isolation region 140 in order to maximize the area of the active region AA capable of photoelectric conversion, the width of the isolation region 140 is greater than the width of another portion of the inactive region NAA Can be made small. For example, in the unit solar cell 100 or the non-cut surface NCS of the semiconductor substrate 10, the first and / or second electrodes 42 and 44 are spaced from the side or edge of the semiconductor substrate 10 by a first distance (D1). This is because undesirable shorts or the like may occur when the first and / or second electrodes 42 and 44 extend to the side or edge of the semiconductor substrate 10. On the other hand, the second long side 111b and the first and / or second electrodes 42 and 44, which are the cut surface CS of the semiconductor substrate 10 of each unit solar cell 100, (D2), which is smaller than the first gap (D2). In the drawing, the first electrode 42 is connected to the second long side 111b, which is the cut surface CS of the semiconductor substrate 10, with the cut line CL and the second cut line CL between the cutout area 140 and the inactive area NAA, And spaced apart by an interval D2. The first and / or second electrodes 42 and 44 are not formed in the isolation region 140 in order to effectively prevent a short circuit or the like. However, the present invention is not limited thereto. Accordingly, the first and second electrodes 42 and 44 are continuously formed in the portion corresponding to the separation region 140 or the cutting line CL in the parent solar cell 100a and then cut to form the first and second electrodes 42, and 44 may be formed in contact with the cut surface CS of the semiconductor substrate 10.

As described above, the electrodes 42 and 44 are formed asymmetrically on the first long side 111a, which is the non-cut surface CS, and the second long side 111b, on the non-cut surface NCS, The first short sides 112a and the second short sides 112b and the first slope sides 113a and the second slope sides 113b may be formed symmetrically with respect to each other.

The presence of the oxide layer 120 having the shape and the thickness of the semiconductor substrate 10 having the long axis and the short axis and the thickness, the material, the lamination structure and the like different from other insulating films and / or the presence of the electrodes 42 and 44 and the semiconductor substrate 10, It can be seen that the unit solar cell 100 is formed by cutting the cutting line CL of the parent solar cell 100a by the difference between the cutting edge CS and the non-cutting edge NCS .

For the sake of simplicity and illustration, the present embodiment illustrates the fabrication of two unit solar cells 100 in one parent solar cell 100a. At this time, the cutting line CL can pass the center of the parent solar cell 100a. Then, each unit solar cell 100 has substantially the same area and can have similar electrical characteristics. Among them, the approximate octagonal parent solar cell 100a is cut to manufacture two unit solar cells 100, whereby each unit solar cell 100 is divided into first and second long sides 111a and 111b, The first and second short sides 112a and 112b, and the first and second slant sides 113a and 113b.

However, the present invention is not limited thereto. Accordingly, the number of the unit solar cells 100 manufactured by one mother solar cell 100a may be one more than the number of the cutting lines CL, and the number of the cutting lines CL may be two or more. When the number of cutting lines CL is two or more, the active areas AA of the respective solar cells 100 may be spaced apart by a uniform distance so as to have substantially the same short axis.

In FIG. 3, for example, three cutting lines CL are provided to illustrate manufacturing four unit solar cells 100 from one parent solar cell 100a.

In this case, when the approximate octagonal parent solar cell 100a is cut as described above, the unit solar cells 100 positioned on the upper and lower sides of the drawing are arranged so that the first and second long sides The first and second short sides (see 112a and 112b in FIG. 1, the same shall apply hereinafter), the first and second inclined sides (see 113a and 113b in FIG. 1, ), The second long side 111b corresponds to the cut surface (CS in FIG. 1, the same applies hereinafter), and the remaining edge corresponds to the non-cut surface (NCS in FIG. The unit solar cell 100 can be applied as described above with reference to FIGS. 1 and 2 as it is.

The unit solar cell 100 located in the center has first and second long sides 111a and 111b and first and second short sides 112a and 112b and has first and second inclined sides 113a and 113b Do not have. The first and second long sides 111a and 111b correspond to the cut surface CS and the first and second short sides 112a and 112b correspond to the non-cut surface NCS. The description with reference to Figs. 1 and 2 above can be applied to the cut surface CS and the non-cut surface NCS. However, since the first and second long sides 111a and 111b are all formed by the cut surface CS, the conductive type regions 20 and 30 and / or the electrodes 42 and 44 are formed at the first and second long sides 111a and 111b, respectively. ) Are positioned symmetrically.

A solar cell panel 200 including the above-described unit solar cell 100 will be described in detail with reference to FIG. 4 is a schematic cross-sectional view of a solar cell panel including the unit solar cell shown in Fig.

4, a solar cell panel 200 according to an embodiment of the present invention includes a unit solar cell 100, a first substrate (hereinafter, referred to as "front substrate") positioned on the front surface of the unit solar cell 100, (Hereinafter referred to as "rear sheet") 203 positioned on the rear surface of the unit solar cell 100. [ The solar cell panel 200 further includes a first sealing material 205a between the unit solar cell 100 and the front substrate 201 and a second sealing material 205b between the unit solar cell 100 and the rear sheet 203 (Not shown). This will be explained in more detail.

The two unit solar cells 100 adjacent to each other are electrically connected to each other (for example, in series) by a connecting member 207. More specifically, the edge portions of the two unit solar cells 100 are positioned so as to be in mutual contact with each other, and the connecting member 207 is connected to the first electrode of the unit solar cell 100 located at the lower side ) And the second electrode (reference numeral 44 in FIG. 2 is equal to or less than that of FIG. 2) of the unit solar cell 100 located at the upper side and electrically and physically connects them. The connection member 270 may be formed of various materials capable of electrically and physically connecting the two unit solar cells 100, and may be formed of a conductive adhesive layer, solder, or the like. These connections are successively repeated so that a plurality of solar cells 100 form one column (or string). The solar cell panel 200 may include one or a plurality of rows of unit solar cells 100. When a plurality of columns are provided, various configurations can be applied to the electrical connection and the like.

The first seal member 205a may be located on the light receiving surface of the unit solar cell 100 and the second seal member 205b may be located on the back surface of the unit solar cell 100. The first seal member 205a, (205b) are adhered by lamination to cut off water and oxygen which may adversely affect the unit solar cell (100), and each element of the unit solar cell (100) can be chemically bonded.

The first sealing material 205a and the second sealing material 205b may be ethylene-vinyl acetate copolymer resin (EVA), polyvinyl butyral, silicon resin, ester-based resin, olefin-based resin, or the like. However, the present invention is not limited thereto. Accordingly, the first and second sealing materials 205a and 205b may be formed by a method other than lamination using various other materials.

The front substrate 201 is positioned on the first sealing material 205a to transmit sunlight and is preferably made of tempered glass in order to protect the unit solar cell 100 from an external impact or the like. Further, it is more preferable to use a low-iron-content tempered glass containing a small amount of iron in order to prevent the reflection of sunlight and increase the transmittance of sunlight. However, the present invention is not limited thereto, and the front substrate 201 may be formed of other materials.

The rear sheet 203 protects the unit solar cell 100 from the back surface of the unit solar cell 100, and functions as a waterproof, insulating, and ultraviolet shielding function. The backsheet 203 may be in the form of a film or a sheet. The back sheet 203 may be a TPT (Tedlar / PET / Tedlar) type or a polyvinylidene fluoride (PVDF) resin formed on at least one side of a polyethylene terephthalate (PET). Poly (vinylidene fluoride) is a polymer having a structure of (CH ₂ CF ₂ ) n and has a double fluorine molecular structure, and therefore has excellent mechanical properties, weather resistance, and ultraviolet ray resistance. However, the present invention is not limited thereto, and the backsheet 203 may be made of another material or the like. At this time, the rear sheet 203 may be a material having a high reflectivity so that sunlight incident from the front substrate 201 can be reflected and reused. However, the present invention is not limited thereto, and the back sheet 203 may be formed of a transparent material (for example, glass) into which solar light can enter, thereby realizing a double-side light receiving solar cell panel 200.

The solar cell panel 200 according to the present embodiment may include the unit solar cell 100 as described above to minimize the output loss after the module process so that the output of the solar cell panel 200 can be maximized.

Hereinafter, a method of manufacturing the unit solar battery 100 according to an embodiment of the present invention will be described in detail with reference to FIGS. 5A and 5B.

5A and 5B are cross-sectional views illustrating a method of manufacturing a unit solar cell according to an embodiment of the present invention. Figs. 5A and 5B are shown based on a cross section taken along the line V-V of Fig.

Conductive regions 20 and 30, electrodes 42 and 44 and insulating films 22 and 24 and 32 are formed on the semiconductor substrate 10 or on the semiconductor substrate 10 as shown in FIG. Thereby forming a battery 100a. Various methods known as the method of forming the parent solar cell 100a can be applied.

Subsequently, as shown in FIG. 5B, a plurality of unit solar cells 100 can be manufactured by a cutting process in which the parent solar cell 100a is cut along the cutting line CL. At this time, in this embodiment, the cutting process is performed by a laser processing process for irradiating the water jet laser 300 along the cutting line CL.

The water jet laser 300 provides a laser with water to reach the parent solar cell 100a while the laser 320 moves into the provided water jet 310 to cut the parent solar cell 100a. More specifically, a water jet (or water column) 310 having a first size (area, width, or diameter) by providing water at a constant water pressure through a nozzle 310a having a predetermined size (area, width, And irradiates a laser 320 having a size (area, width, or diameter) smaller than the width of the water jet 310 by the lens 300a. The air gap 312 is located at the periphery of the water jet 310 so that the laser 320 is moved in the water jet 310 several times in a state in which the laser 320 is not out of the water jet 310 due to total reflection, Reaches the parent solar cell 100a while being refracted, and cuts the parent solar cell 100a.

At this time, in the portion irradiated with the laser 320, the parent solar cell 100a is locally heated to a certain temperature or higher by the energy of the laser 320. [ As a result, the portion of the parent solar cell 100a irradiated with the laser 320 is heated and the parent solar cell 100a is cut along the cutting line CL. In this embodiment, since water is supplied by the water jet 310 together with the laser 320, the heating temperature of the parent solar cell 100a is lowered by the laser 320, and the travel path of the laser 320 is longer The excessive heating or damage of the solar cell 100a can be prevented. The temperature of the water jet 310 is not limited, but may be provided as it is without any special treatment, and it may have a room temperature. As an example, the temperature of the water jet 310 may be between 5 ° C and 30 ° C. In this embodiment, the parent solar cell 100a can be locally heated by the laser 320. [ For example, when the temperature of the portion cut by the laser 320 in the parent solar cell 100a or the temperature of the water reaching the cut portion is lower than or equal to 150 占 폚 (for example, 100 占 폚 or lower, Lt; 0 > C). The excessive heating or damage of the parent solar cell 100a can be effectively prevented within this range. However, the present invention is not limited thereto.

The energy loss that may occur due to the heating temperature of the laser 320 being somewhat lowered and the travel path of the laser 320 becoming longer can be supplemented by the water jet 310 provided at a constant water pressure. Thus, the parent solar cell 100a can be stably cut without losing the total energy for cutting the parent solar cell 100a.

The width or diameter of the water jet 310 may be equal to or less than the width or diameter of the water jet 310 and the width or diameter of the laser beam of the laser 320 may be equal to or less than the width or diameter of the water jet 310. [ Since the width or diameter of the water jet 310 is actually related to the width of the cut portion 130, it is limited in consideration of the width of the cut portion 130. The width or diameter of the laser beam of the laser 320 is smaller than that of the water jet 310 so that it can move inside the water jet 310. In one example, the width or diameter of the laser beam of laser 320 may be between 15 and 50 um. However, the present invention is not limited thereto, and the value of the width or the diameter of the laser beam of the water jet 310 or the laser 320 may vary.

At this time, the laser 320 may be a green laser having a wavelength of about 532 nm. The green laser has a very good property of penetrating the inside of the water jet 310 and can be stably reached to the parent solar cell 100a even if it is provided together with the water jet 310. [

In one example, the laser 320 may be a pulsed wave laser that has an output for a period of time in a pulse waveform and no output for a period of time. Accordingly, sufficient energy is supplied to the parent solar cell 100a in a short time, and the parent solar cell 100a can be easily cut. On the other hand, a continuous wave laser having a constant and continuous output unlike the present embodiment may be difficult to provide sufficient energy to cut the parent solar cell 100a. However, the present invention is not limited thereto.

And the pulse width of the laser 320 may be 80 to 600 nsec. If the pulse width of the laser 320 is increased as described above, energy required for cutting the parent solar cell 100a can be sufficiently provided even when energy loss due to the water jet 310 is somewhat small. On the other hand, the pulse width of the laser used for processing materials other than the parent solar cell 100a is about 10 to 15 nsec, which is quite different from the present embodiment.

The water jet 310 may be provided at a desired water pressure by a pump (not shown). In one example, the water pressure of the water jet 310 may be between 100 bar and 500 bar (e.g., 300 bar or 500 bar). The water pressure of the water jet 310 can be stably cut in consideration of an energy loss that may occur due to a somewhat lower heating temperature by the laser 320 and a longer travel path of the laser 320 . If the water pressure of the water jet 310 is less than 100 bar, it may not be sufficient to compensate for the energy loss, and if the water pressure of the water jet 310 exceeds 500 bar, It is possible to damage the solar cell 100a. However, the present invention is not limited thereto.

The width of the cut portion 130 formed by the laser processing using the water jet 300 may have various values. For example, the width of the cut portion 130 may be 250um or less (for example, 60um to 80um). The width of the cut portion 130 may be greater than the width of the water jet 310. This is because the cut portion 130 can be formed at the portion where the water jet 310 reaches and the portion adjacent thereto. If the width of the cut portion 130 exceeds 250 袖 m, the area not contributing to photoelectric conversion in the parent solar cell 100a or the unit solar cell 100 can be increased. Considering the area contributing to photoelectric conversion, the width of the cutout 130 may be less than 80 um. If the width of the cut portion 130 is less than 60 袖 m, cutting may not be performed well.

In this embodiment, the water jet laser 300 includes conductive regions 20 and 30 (e.g., a second conductive region 30) having the same conductivity type as the backside of the semiconductor substrate 10 or the base region 110, Can be located. This is to minimize the possibility of damaging the pn junction when the laser is irradiated on the surface of the semiconductor substrate 10 or on the surface that functions as the emitter region. More specifically, when heat generated by the water jet laser 300 directly reaches the pn junction, damage to the pn junction occurs to generate a leakage current to lower the fill factor (FF) And the shortcircuit current Ics may also be lowered, and the efficiency of the solar cell 100 may be lowered. However, the present invention is not limited to the water jet laser irradiation direction.

The oxide layer 120 is formed on the cut surface CS of the unit solar cell 100 during the laser processing process in which the water jet laser 300 is irradiated. This is because the oxygen in the water (H ₂ O) contained in the laser 320, the cut surface (CS) with oxygen gas or water jet (310) contained in the semiconductor material of the semiconductor substrate 10 is locally heated in the vicinity of the air by Can be formed by reaction. The oxide layer 120 thus formed may have a thickness of less than 100 nm (e.g., 30 nm to 70 nm). Since the oxide layer 120 is formed without a separate deposition process, it is not necessary to form a separate passivation film on the cut surface CS, thereby simplifying the process. Whether or not the oxide layer 120 is present on the cut surface CS can be confirmed by X-ray photoelectron spectroscopy (XPS).

As described above, in the present embodiment, the cutting process includes the laser processing step using the water jet laser 300, thereby effectively preventing the damage of the parent solar cell 100a or the unit solar cell 100, The unit solar cell 100 can be manufactured by cutting. At this time, since the oxide layer 120 is formed on the cut surface CS during the laser machining process by the water jet laser 300, a process for passivating the cut surface CS may not be additionally required. Accordingly, the manufacturing process can be simplified and can be applied to the parent solar cell 100a having various structures. On the other hand, if the cut surface CS is not passivated after the cutting process, the characteristics of the unit solar cell 100 may be degraded. In order to prevent this, an insulating film is formed separately after the cutting process, or an oxidized layer is formed by supplying oxygen or the like to cover the already formed electrodes 42, 44. Accordingly, it is necessary to add an etching process for exposing the electrodes 42 and 44 to the outside, which complicates the process. The conductive regions 20 and 30 and the electrodes 42 and 44, which have already been formed by the etching process, And the like.

In the above-described embodiment, the cutting portion 130 penetrating the parent solar cell 100a is formed in the laser processing step to cut the parent solar cell 100a. However, the present invention is not limited thereto. Other examples will be described in detail with reference to Figs. 6A to 6B. 5A and 5B, detailed description of the same or extremely similar elements will be omitted, and only different portions will be described in detail.

6A and 6B are cross-sectional views illustrating a method of manufacturing a unit solar cell according to another embodiment of the present invention. FIGS. 6A and 6B are views based on a cross section taken along the line V-V of FIG.

6A, a cutting groove 130a is formed in which a part of the mother solar cell 100a or the semiconductor substrate 10 in the thickness direction is removed by a laser machining process using the water jet laser 300 .

For example, the ratio (T3 / T2) of the depth T3 of the cut groove 130a to the thickness T2 of the parent solar cell 100a or the semiconductor substrate 10 may be 10% to 70%. If the ratio T3 / T2 is less than 10%, cutting of the semiconductor substrate 10 may not be performed neatly even if mechanical processing is performed later. If the ratio T3 / T2 exceeds 70%, the laser energy to be irradiated increases to change the characteristics of the parent solar cell 100a or the unit solar cell 100 or to change the characteristics of the semiconductor substrate 10 or the unit solar cell 100 ) May be impacted or damaged. The depth T3 of the cut groove 130a is larger than the thickness of the conductive type regions 20 and 30 so that stable cutting can be performed. However, the present invention is not limited thereto.

Then, as shown in FIG. 6B, a mechanical processing step of applying a physical impact may be performed to form the cut portion 130 passing through the parent solar cell 100a. According to this, even the narrow cutting portion 130 can be cut with minimized structural impact while having a clean working surface. Since the portion of the semiconductor substrate 10 adjacent to the cut surface CS is locally heated even when a physical impact is applied thereto, it can react with oxygen gas or the like in the atmosphere, so that the oxide layer 120 . As a result, the oxide layer 120 is formed while covering the entire cut surface CS, thereby improving the passivation characteristics. However, the present invention is not limited thereto, and the oxide layer 120 may be partially formed only on the portion formed by the laser machining process of the cut surface CS.

In the present invention, a unit solar cell 100 having various structures can be manufactured. As another example, a unit solar cell 100 having a different structure will be described with reference to FIGS. 7 and 8. FIG. 1 to 4, 5A and 5B, 6A and 6B, and the same or very similar elements will be described in detail with respect to different parts, with the detailed description omitted. In addition to this structure, a unit solar cell 100 having various structures can be applied. For simplicity and clarity, only the basic structure of the unit solar cell 100 is shown in FIGS. 7 and 8, but the cut and uncut surfaces are not shown.

7 is a cross-sectional view illustrating a unit solar cell according to another embodiment of the present invention.

Referring to FIG. 7, in this embodiment, a first intermediate passivation film (or first tunneling film) 52 is located on the front surface of the semiconductor substrate 10, and a first conductive type region 20 is disposed thereon. The first electrode 42 includes a first transparent electrode layer 420 entirely disposed on the first conductive type region 20 and a first metal electrode layer 422 disposed on the first transparent electrode layer 420 and having a pattern do.

Here, the first intermediate passivation film 52 may be formed entirely on the front surface of the semiconductor substrate 10. The thickness of the first intermediate passivation film 52 may be less than the thickness of the first conductive type region 20 since carriers are transferred to the first conductive type region 20 through the first intermediate passivation film 52 . As an example, the first intermediate passivation film 52 may be formed of an intrinsic amorphous silicon (ia-Si) layer, an intrinsic amorphous silicon carbide (ia-SiCx) SiOx) layer.

The first conductive type region 20 may be formed of a semiconductor layer that is positioned separately from the semiconductor substrate 10 and the first conductive type region 20 may have a structure different from that of the semiconductor substrate 10, . As an example, the first conductivity type region 20 may include an amorphous silicon (a-Si) layer, an amorphous silicon oxide (a-SiOx) layer, an amorphous silicon carbide (a-SiCx) layer, an indium- a gallium-zinc oxide (IGZO) layer, a titanium oxide (TiOx) layer, and a molybdenum oxide (MoOx) layer. At this time, the amorphous silicon (a-Si) layer, the amorphous silicon oxide (a-SiOx) layer, and the amorphous silicon carbide (a-SiCx) layer may be doped with the first conductivity type dopant.

In this embodiment, the first transparent electrode layer 420 is entirely formed and the first metal electrode layer 420 may have the shape of the first electrode (reference numeral 42 in Fig. 1) shown in Figs. 1, 3 and 4 have. Accordingly, the first metal electrode layer 420 may include a finger electrode and a bus bar electrode. 1) and the finger electrode (reference numeral 42a in Fig. 1) described with reference to Fig. 1 and the bus electrode 42a and the bus electrode 42a of the first metal electrode layer 420, The details of the electrode (reference numeral 42b in FIG. 1) can be applied as it is, and a detailed description thereof will be omitted.

Since the first transparent electrode layer 420 is entirely formed on the first conductive type region 20, the first transparent electrode layer 420 may be formed of a material capable of transmitting light (a transparent material). For example, the first transparent electrode layer 420 may include at least one of indium tin oxide (ITO), aluminum zinc oxide (AZO), boron zinc oxide (BZO), indium tungsten And may include at least one of indium tungsten oxide (IWO) and indium cesium oxide (ICO). However, the present invention is not limited thereto and may include the first transparent electrode layer 420 and various other materials.

Similarly, a second intermediate passivation film 54 is located on the backside of the semiconductor substrate 10 and a second conductive type region 30 is located thereon. The second electrode 44 includes a second transparent electrode layer 440 located entirely on the second conductive type region 30 and a second metal electrode layer 442 located on the second transparent electrode layer 440 and having a pattern do. The description of the second conductivity type region 30 is the same as that of the first conductivity type region 20 except that the second conductivity type region 30 has the second conductivity type. The description of the first intermediate passivation film 52 and the first electrode 42 may be applied to the second intermediate passivation film 54 and the second electrode 44 as they are.

In this structure, the semiconductor substrate 10 may be composed of a base region 110 having no additional doping region. As a result, damage or degradation of the semiconductor substrate 10, which may be caused by a doping process for forming a separate doped region, can be greatly reduced. The base region 110 may have a first or second conductivity type.

Although the first and second conductivity type regions 20 and 30 are formed as separate layers from the semiconductor substrate 10 in the drawing, the present invention is not limited thereto. Therefore, one of the first and second conductivity type regions 20 and 30 may be composed of a doped region formed in the semiconductor substrate 10. [

8 is a cross-sectional view illustrating a unit solar cell according to another embodiment of the present invention.

8, an intermediate passivation film (or tunneling film) 56 is located on the rear surface of the semiconductor substrate 10 and a first and a second conductive type The regions 20 and 30 can be located. For example, a barrier region 40 comprised of an undoped material (e.g., an intrinsic semiconductor, e.g., intrinsic silicon) may be located between the first and second conductivity type regions 20, have. A front electric field area 150 may be positioned on the front surface of the semiconductor substrate 10 and a first passivation film 22 and an antireflection film 24 may be positioned thereon. The front field region 150 may be a doping region having the same conductivity type as the base region 110 and having a doping concentration higher than that of the base region 110. However, the present invention is not limited thereto, and the front electric field area 150 may be formed separately from the semiconductor substrate 10 on the semiconductor substrate 10.

For example, an antireflection structure may be formed on a front surface of the semiconductor substrate 10, and a rear surface of the semiconductor substrate 10 may be a mirror polished surface. This is because the characteristics of the intermediate passivation film 56 can greatly change the carrier transport characteristics and the like.

The intermediate passivation film 56 serves as a kind of barrier for electrons and holes and prevents the minority carriers from passing therethrough so that after the intermediate passivation film 56 is accumulated at a portion adjacent to the intermediate passivation film 56, Only a majority carrier can pass through the intermediate passivation film 56. The intermediate passivation film 56 may also serve as a diffusion barrier to prevent the dopants of the conductive regions 32 and 34 from diffusing into the semiconductor substrate 10. [ The intermediate passivation film 56 may include amorphous silicon, an oxide, a nitride, a semiconductor, a conductive polymer, or the like. For example, intermediate passivation film 56 may comprise silicon oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, intrinsic polycrystalline silicon, and the like. As an example, the intermediate passivation film 56 may be an insulating material such as an oxide, a nitride, etc., and in particular may be composed of a silicon oxide layer comprising silicon oxide. This is because the silicon oxide layer is a film which has excellent passivation characteristics and is susceptible to tunneling of the carrier.

The first and second conductivity type regions 20 and 30 may be formed of a semiconductor layer that is separate from the semiconductor substrate 10 and may have a crystal structure different from that of the semiconductor substrate 10. For example, the semiconductor substrate 10 may have a single crystal structure, and the first and second conductivity type regions 20 and 30 may have a polycrystalline structure.

The first electrode 42 and the second electrode 44 may include elongated portions extending in a straight line shape and the first electrode 42 and the second electrode 44 may be alternately arranged in a direction crossing the extending direction, . However, the present invention is not limited thereto, and the first electrode 42 and the second electrode 44 may have different shapes.

In the unit solar cell 100 according to the present embodiment, the first and second electrodes 42 and 44 are all located on the rear surface side of the semiconductor substrate 10, can do.

In the laser machining step, a water jet laser (reference numerals 300 and 310 in FIG. 5B, the same applies hereinafter) is formed on the rear surface of the solar cell 100 or the semiconductor substrate 10 in the portion where the second conductivity type region 30 is located. Lt; / RTI > This is because if the water jet laser 300 is irradiated on the entire surface of the solar cell 100 or the semiconductor substrate 10 where the conductive type regions 20 and 30 are not located, a large number of recombination sites can be generated. The water jet laser 300 is irradiated to the portion where the second conductivity type region 30 is located rather than the portion where the first conductivity type region 20 forming the pn junction is located to maintain the characteristics of the solar cell 100 . However, the present invention is not limited thereto.

Features, structures, effects and the like according to the above-described embodiments are included in at least one embodiment of the present invention, and the present invention is not limited to only one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

100a: Mo solar cell
100: Unit solar cell
20: first conductivity type region
30: second conductivity type region
42: first electrode
44: Second electrode
200: Solar panel
300: Water jet laser
310: Water Jet
320: laser

Claims (20)

And cutting the parent solar cell to produce a plurality of unit solar cells,
Wherein the cutting step includes a laser processing step using a water jet laser. The method according to claim 1,
Wherein an oxide layer is formed on the cut surface of the unit solar cell by the laser processing step using the water jet laser in the cutting step. 3. The method of claim 2,
Wherein the parent solar cell comprises an insulating film,
Wherein the thickness of the oxide layer is thinner than the thickness of the insulating film. The method of claim 3,
Wherein the thickness of the oxide layer is less than 100 nm. The method according to claim 1,
Wherein the portion of the parent solar cell is locally heated to 100 or less in the laser processing step. The method according to claim 1,
In the laser processing step, a water jet having a first size and a laser having a second size smaller than the first size are provided together so that the laser moves while being refracted by total reflection in the water jet, And cutting the parent solar cell together with the water pressure of the water jet. The method according to claim 6,
Wherein the water jet has a width or diameter of 20 to 50 mu m,
Wherein a width or a diameter of the laser beam of the laser is in the range of 15 to 50 mu m. The method according to claim 6,
And the water pressure of the water jet is 100 to 500 bar. The method according to claim 6,
Wherein the laser is a green laser. The method according to claim 6,
Wherein the laser is a pulsed laser. 11. The method of claim 10,
Wherein the laser has a pulse width of 80 to 600 nsec. The method according to claim 1,
Wherein a width of the cut portion formed by the laser processing step is 250um or less. The method according to claim 1,
Wherein the parent solar cell or the unit solar cell comprises a semiconductor substrate including a base region, a first conductive type region having a conductivity type different from that of the base region, and a second conductive type region having the same conductivity type as the base region, / RTI >
Wherein the water jet laser is irradiated to one surface of the parent solar cell on which the second conductivity type region is formed or the rear surface of the parent solar cell in the laser processing step. The method according to claim 1,
A cutting groove in which a part of the parent solar cell is removed in the laser processing step,
Wherein the cutting step further comprises a mechanical working step of applying a physical impact to the parent solar cell after the laser processing step. A semiconductor substrate including a side surface having a cut surface and a non-cut surface;
A conductive type region formed on the semiconductor substrate or on the semiconductor substrate;
An electrode connected to the conductive region;
An oxide layer formed on the cut surface; And
The insulating film formed on the non-
/ RTI >
Wherein the thickness of the oxide layer is smaller than the thickness of the insulating film. 16. The method of claim 15,
Wherein the thickness of the oxide layer is less than 100 nm,
Wherein a thickness of the insulating film is 100 nm or more. 16. The method of claim 15,
Wherein the oxide layer is composed of a single layer,
Wherein the insulating film is composed of a plurality of layers. 16. The method of claim 15,
Wherein the insulating film includes a material different from the oxide layer, or at least one of the insulating films includes a material different from the oxide layer. 16. The method of claim 15,
Wherein a gap between the electrode and the cut surface is smaller than a gap between the electrode and the non-cut surface. 16. The method of claim 15,
Wherein the electrode includes a plurality of finger electrodes formed along a first direction and a bus bar electrode formed along a second direction intersecting the first direction,
Wherein the solar cell has a long side and a short side,
The cut surface is located at a side surface along at least one of the long sides,
Wherein the long side is formed in the first direction and the short side is formed in the second direction.

Images