KR101072067B1 - Tip, solar cell and method of fabricating the solar cell using the tip - Google Patents

Abstract

The solar cell according to the embodiment includes a plurality of back electrode patterns spaced apart from each other on a substrate; A light absorbing layer having a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; A front electrode disposed on the light absorbing layer and spaced apart by the separation pattern, wherein the front electrode is inserted into the contact pattern to be electrically connected to the back electrode pattern and has a width of an upper portion of the contact pattern; It includes a wider than the width of the lower portion of the contact pattern in contact with the front electrode pattern.

Solar cell

Description

TIP, SOLAR CELL AND METHOD OF FABRICATING THE SOLAR CELL USING THE TIP}

Embodiment relates to a tip, a solar cell and a method of manufacturing a solar cell using the same.

Recently, as the demand for energy increases, development of solar cells for converting solar energy into electrical energy is in progress.

In particular, CIGS-based solar cells, which are pn heterojunction devices having a substrate structure including a glass substrate, a metal back electrode layer, a p-type CIGS-based light absorbing layer, a high resistance buffer layer, an n-type window layer, and the like, are widely used.

However, in the CIGS solar cell, the front electrode is inserted into the separation pattern formed to connect the front electrode and the rear electrode to be electrically connected to the rear electrode. However, the width of the separation pattern is narrow, and voids are formed inside the separation pattern when forming the front electrode. void) can be generated to increase the resistance of the solar cell electrical properties can be degraded.

The embodiment provides a tip, a solar cell, and a solar cell manufacturing method using the same, which can reduce defects when forming an upper electrode of the solar cell.

The solar cell according to the embodiment includes a plurality of back electrode patterns spaced apart from each other on a substrate; A light absorbing layer having a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; A front electrode disposed on the light absorbing layer and spaced apart by the separation pattern, wherein the front electrode is inserted into the contact pattern to be electrically connected to the back electrode pattern and has a width of an upper portion of the contact pattern; It includes a wider than the width of the lower portion of the contact pattern in contact with the front electrode pattern.

A method of manufacturing a solar cell according to an embodiment includes forming a plurality of back electrode patterns spaced apart from each other on a substrate; Forming a light absorbing layer including a contact pattern for connection between electrodes on the substrate on which the rear electrode pattern is disposed; Forming a front electrode on the light absorbing layer; And forming a separation pattern for etching the front electrode and the light absorbing layer into unit cells, wherein the front electrode is inserted into the contact pattern and electrically connected to the back electrode pattern. The width of the includes a wider than the width of the lower portion of the contact pattern in contact with the front electrode.

Tip according to the embodiment is a tip of the scribing apparatus used in the manufacturing process of the solar cell, the contact portion capable of scribing the scribing object; And a support part for supporting the contact part, wherein a width of an upper part of the contact part is greater than a width of a lower part, and an outer angle θ of the lower part of the contact part contacted for scribing and the side wall of the contact part is 45 To achieve ˜80 °.

According to an embodiment, a tip, a solar cell, and a solar cell manufacturing method using the same form a width W2 of an upper portion of a contact pattern wider than a width W1 of a lower portion thereof, so that voids are generated in an area in contact with the rear electrode pattern. Can be prevented.

That is, the contact pattern of the structure improves the step coverage of the front electrode, thereby reducing the contact resistance, thereby improving the electrical characteristics of the solar cell.

In the description of the embodiments, where each substrate, layer, film, or electrode is described as being formed "on" or "under" of each substrate, layer, film, or electrode, etc. , "On" and "under" include both "directly" or "indirectly" formed through other components. In addition, the upper or lower reference of each component is described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

7 is a side cross-sectional view showing a solar cell according to an embodiment.

As shown in FIG. 7, the solar cell according to the embodiment includes a substrate 100, a back electrode pattern 200, a light absorbing layer 300, and a front electrode 500.

The back electrode patterns 200 are spaced apart from each other on the substrate 100, and the light absorbing layer 300 is a contact pattern 310 and a unit cell for connection between electrodes on the substrate 100. It includes a separation pattern 320 for dividing by.

The front electrode 500 is disposed on the light absorbing layer 300, spaced apart by the separation pattern 320, and inserted into the contact pattern 310 to be electrically connected to the back electrode pattern 200. Connected.

The width W2 of the upper portion of the contact pattern 310 is wider than the width W1 of the lower portion of the contact pattern 310 in contact with the front electrode pattern 200.

In this case, the angle θ formed between the surface of the back electrode pattern 200 and the sidewall of the region where the light absorbing layer 300 is in contact with each other may be 45 ° to 80 °, and the angle θ is the light absorbing layer ( The angle within 300).

5 illustrates a structure of a tip according to an embodiment.

The tip 600 according to the embodiment is used in a scribing process for forming a contact pattern and a separation pattern when manufacturing a solar cell.

The tip 600 includes a support part 650 and a contact part 660, and the lower surface 610 of the scribing part 650 has a light absorbing layer 300 and a scribing process for forming a solar cell. It may be in contact with the buffer layer 400.

In this case, the tip 600 is formed such that the width T2 of the upper portion of the contact portion 660 is larger than the width T1 of the lower portion in order to scrib the light absorbing layer 300 and the buffer layer 400. do.

An outer angle θ of the lower surface 610 and the sidewall of the tip 600 contacted by the tip 600 may be 45 ° to 80 °.

A more detailed description of the solar cell and the tip of the present embodiment will be described with the manufacturing method of the solar cell.

1 to 7 are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment.

First, as shown in FIG. 1, the back electrode 201 is formed on the substrate 100.

The substrate 100 may be glass, and a ceramic substrate such as alumina, stainless steel, a titanium substrate, or a polymer substrate may also be used.

Soda lime glass may be used as the glass substrate, and polyimide may be used as the polymer substrate.

In addition, the substrate 100 may be rigid or flexible.

The back electrode 201 may be formed of a conductor such as metal.

For example, the back electrode 201 may be formed by a sputtering process using a molybdenum (Mo) target.

This is because of high electrical conductivity of molybdenum (Mo), ohmic bonding with the light absorbing layer, and high temperature stability under Se atmosphere.

In addition, although not shown in the drawing, the back electrode 201 may be formed of at least one layer.

When the back electrode 201 is formed of a plurality of layers, the layers constituting the back electrode 201 may be formed of different materials.

Subsequently, as shown in FIG. 2, a patterning process is performed on the back electrode 201 to form a back electrode pattern 200.

The back electrode pattern 200 may be formed such that the substrate 100 is exposed between the protection patterns 10.

In addition, the back electrode pattern 200 may be arranged in a stripe form or a matrix form and may correspond to each cell.

However, the back electrode pattern 200 is not limited to the above form and may be formed in various forms.

As shown in FIG. 3, the light absorbing layer 300 and the buffer layer 400 are formed on the back electrode pattern 200.

The light absorbing layer 300 includes an Ib-IIIb-VIb-based compound.

In more detail, the light absorbing layer 300 includes a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ , CIGS-based) compound.

Alternatively, the light absorbing layer 300 may include a copper-indium selenide-based (CuInSe ₂ , CIS-based) compound or a copper-gallium-selenide-based (CuGaSe ₂ , CIS-based) compound.

For example, to form the light absorbing layer 300, a CIG-based metal precursor film is formed on the back electrode pattern 200 using a copper target, an indium target, and a gallium target.

Thereafter, the metal precursor film is reacted with selenium (Se) by a selenization process to form a CIGS-based light absorbing layer 300.

In addition, during the process of forming the metal precursor film and the selenization process, an alkali component included in the substrate 100 may pass through the back electrode pattern 200, and the metal precursor film and the light absorbing layer ( 300).

An alkali component may improve grain size and improve crystallinity of the light absorbing layer 300.

In addition, the light absorbing layer 300 may form copper, indium, gallium, selenide (Cu, In, Ga, Se) by co-evaporation.

The light absorbing layer 300 receives external light and converts the light into electrical energy. The light absorbing layer 300 generates photo electromotive force by the photoelectric effect.

The buffer layer 400 is formed of at least one layer, and any one or a stack of cadmium sulfide (CdS), ITO, ZnO, and i-ZnO on the substrate 100 on which the light absorbing layer 300 is formed. It can be formed as.

In this case, the buffer layer 400 is an n-type semiconductor layer, the light absorbing layer 300 is a p-type semiconductor layer. Thus, the light absorbing layer 300 and the buffer layer 400 form a pn junction.

The buffer layer 400 is disposed between the light absorbing layer 300 and the front electrode to be formed later.

That is, since the difference between the lattice constant and the energy band gap is large between the light absorbing layer 300 and the front electrode, a good junction may be formed by inserting the buffer layer 400 having a band gap between the two materials.

In the present exemplary embodiment, one buffer layer is formed on the light absorbing layer 300, but the present invention is not limited thereto, and the buffer layer may be formed of a plurality of layers.

Subsequently, as shown in FIG. 4A, a contact pattern 310 penetrating the light absorbing layer 300 and the buffer layer 400 is formed.

The contact pattern 310 may be formed by a mechanical method, and a portion of the back electrode pattern 200 is exposed.

That is, the contact pattern 310 may be formed by removing a portion of the light absorbing layer 300 and the buffer layer 400 with a tip 600 illustrated in FIG. 5.

The tip 600 includes a support part 650 and a contact part 660, and the lower surface 610 of the scribing part 650 is formed of the light absorbing layer 300 and the buffer layer 400 during the scribing process. Can be contacted.

In this case, the tip 600 is formed such that the width T2 of the upper portion of the contact portion 660 is larger than the width T1 of the lower portion in order to scrib the light absorbing layer 300 and the buffer layer 400. do.

In addition, the contact pattern 310 is formed in the same shape as that of the contact portion 660.

An outer angle θ of the lower surface 610 and the sidewall of the tip 600 contacted by the tip 600 may be 45 ° to 80 °.

Due to the tip 600, the contact pattern 310 is formed such that the upper width W2 is wider than the lower width W1.

In other words, the tip 600 also has an upper width T2 wider than the lower width T1, and the upper width T2 of the tip 600 is the upper width T2 of the contact pattern 310. The width T1 of the lower portion of the tip 600 is the same as the width W1 of the lower portion of the contact pattern 310.

The contact pattern 310 formed as described above is formed such that the width W2 of the upper portion is wider than the width W1 of the lower portion so that the sidewall of the region where the surface of the back electrode pattern 200 is in contact with the light absorbing layer 300 is formed. The angle θ may be 45 to 80 °.

That is, the exposed portion of the region where the sidewall of the contact pattern 310 and the back electrode pattern 200 contact each other may form an angle of 100 ° to 135 °.

In addition, as shown in FIG. 4B, the surface where the light absorbing layer 300 is in contact with the back electrode pattern 200 may be rounded.

In this case, the angle θ formed in the light absorbing layer 300 at the intersection of the extension line I by the sidewall of the light absorbing layer 300 and the extension line I 'by the surface of the back electrode pattern 200. This can be 45 to 80 °.

The upper width W2 of the contact pattern 310 is formed to be wider than the lower width W1, so that voids generated in the contact pattern 310 may be prevented when the front electrode is formed. .

As shown in FIG. 6, a transparent conductive material is stacked on the buffer layer 400 to form the front electrode 500 and the connection wiring 700.

When the transparent conductive material is stacked on the buffer layer 400, the transparent conductive material may also be inserted into the contact pattern 310 to form the connection wiring 700.

The back electrode pattern 200 and the front electrode 500 are electrically connected to each other by the connection wiring 700.

In this case, the width W2 of the upper portion of the contact pattern 310 may be formed wider than the width W1 of the lower portion thereof, thereby preventing voids from occurring in an area in contact with the back electrode pattern 200.

That is, due to the contact pattern 310 of the structure, the step coverage of the front electrode 500 is improved, and the contact resistance is reduced, thereby improving the electrical characteristics of the solar cell.

The front electrode 500 is formed of zinc oxide doped with aluminum by performing a sputtering process on the buffer layer 400.

The front electrode 500 is a window layer forming a pn junction with the light absorbing layer 300. Since the front electrode 500 functions as a transparent electrode on the front of the solar cell, zinc oxide (ZnO) having high light transmittance and good electrical conductivity is provided. Is formed.

In this case, an electrode having a low resistance value may be formed by doping aluminum to the zinc oxide.

The zinc oxide thin film which is the front electrode 500 may be formed by a method of depositing using a ZnO target by RF sputtering, reactive sputtering using a Zn target, and organometallic chemical vapor deposition.

In addition, a double structure in which an indium thin oxide (ITO) thin film having excellent electro-optic properties is laminated on a zinc oxide thin film may be formed.

Subsequently, as shown in FIG. 7, a separation pattern 320 penetrating the light absorbing layer 300, the buffer layer 400, and the front electrode 500 is formed.

The separation pattern 320 may be formed by irradiating a laser or by a mechanical method.

The buffer layer 400 and the front electrode 500 may be separated by the separation pattern 320, and the cells C1 and C2 may be separated from each other by the separation pattern 320.

In addition, the buffer layer 400 and the light absorbing layer 300 may be arranged in the form of a stripe or a matrix by the separation pattern 320.

The separation pattern 300 is not limited to the above form and may be formed in various forms.

Cells C1 and C2 including the back electrode pattern 200, the light absorbing layer 300, the buffer layer 400, and the front electrode 500 are formed by the separation pattern 320.

In this case, each of the cells C1 and C2 may be connected to each other by the connection wiring 700. That is, the connection wiring 700 electrically connects the back electrode pattern 200 of the second cell C2 and the front electrode 500 of the first cell C1 adjacent to the second cell C2. do.

The tip, the solar cell, and the solar cell manufacturing method using the same according to the above-described embodiment form a width W2 of the upper portion of the contact pattern wider than the width W1 of the lower portion, thereby voiding the area in contact with the rear electrode pattern. Can be prevented from occurring.

In other words, the contact pattern of the structure improves the step coverage of the front electrode, thereby reducing the contact resistance and improving the reliability of the solar cell.

Although the above description has been made based on the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains may not have been exemplified above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 to 6 are cross-sectional views illustrating a method of manufacturing a solar cell according to an embodiment.

Claims (6)

A plurality of back electrode patterns spaced apart from each other on the substrate; A light absorbing layer having a contact pattern for inter-electrode connection and a separation pattern for dividing into unit cells on the substrate on which the rear electrode pattern is disposed; A front electrode disposed on the light absorbing layer and spaced apart by the separation pattern; The front electrode is inserted into the contact pattern and electrically connected to the back electrode pattern, and a width of an upper portion of the contact pattern is wider than a width of a lower portion of the contact pattern in contact with the front electrode pattern. The intersection point of the extension line of the surface of the said back electrode pattern and the extension line by the side wall of the said light absorption layer, Comprising: The angle ((theta)) which the said intersection makes in the said light absorption layer is 45-80 degrees. delete Forming a plurality of back electrode patterns spaced apart from each other on the substrate; Forming a light absorbing layer including a contact pattern for connection between electrodes on the substrate on which the rear electrode pattern is disposed; Forming a front electrode on the light absorbing layer; And Etching the front electrode and the light absorbing layer to form a separation pattern for dividing into unit cells; The front electrode is inserted into the contact pattern and electrically connected to the back electrode pattern, and the width of the upper portion of the contact pattern is wider than the width of the lower portion of the contact pattern in contact with the front electrode. The intersection point of the extension line of the surface of the said back electrode pattern and the extension line by the side wall of the said light absorbing layer WHEREIN: The manufacturing method of the solar cell containing the angle ((theta)) made in the said light absorbing layer is 45-80 degrees. delete The method of claim 3, The contact pattern is a solar cell manufacturing method comprising a scribing (scribing) process using a tip (tip) formed wider than the width of the bottom. In the tip of the scribing apparatus used in the manufacturing process of the solar cell, A contact portion capable of scribing a scribing object; And A support for supporting the contact portion, The width of the upper portion of the contact portion is formed larger than the width of the lower portion, A tip comprising a bottom surface of the contact portion contacted for scribing and an outer angle [theta] by the side wall of the contact portion make 45-80 [deg.].

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