TWI538229B - Method for manufacturing thin film solar cell panel - Google Patents

Description

Method for manufacturing thin film solar panel

The present invention relates to a manufacturing method for reducing the series resistance of a thin film solar cell, and more particularly to a method for manufacturing a thin film solar cell capable of reducing contact resistance between electrode layers.

The thin film solar cell is composed of a substrate, a back electrode layer, an absorbing layer, a buffer layer and a transparent conductive layer. Figure 1 shows a schematic diagram of a cell in a conventional thin film solar cell. A back electrode layer 112 of the thin film solar cell unit 100 is disposed on a substrate 111. The back electrode layer 112 may be, for example, a molybdenum metal layer. An absorbing layer 113 is disposed on the back electrode layer 112. A buffer layer 114 is disposed on the absorbing layer 113. A transparent conductive layer 115 is disposed on the buffer layer 114. The transparent conductive layer 115 may be gallium doped ZnO (GZO), boron doped ZnO (BZO), indium tin oxide (ITO) or aluminum doped zinc oxide (Al doped ZnO, AZO). ) layer and so on.

Figure 2 shows a schematic of a conventional thin film solar cell. Hereinafter, a method of manufacturing a conventional thin film solar cell will be described with reference to FIG. 2, which comprises the following steps.

Step S02: forming a back electrode layer 112 on a substrate 111. For example, a layer of molybdenum metal may be deposited as the back electrode layer 112. Step S03: A first patterning process P1 is performed to separate the back electrode layer 112. Step S04: forming an absorbing layer 113 on the back electrode layer 112. Step S05: forming a buffer layer 114 on the absorption layer 113. Step S06: The second patterning process P2 is performed, and the absorption layer 113 and the buffer layer 114 which are semiconductor layers are mechanically separated by a cutter. Step S07: forming a transparent conductive layer 115 on the buffer layer 114. For example, a GZO, BZO, ITO or AZO layer can be deposited as a transparent guide The electrical layer 115, at this time in the region where the absorption layer and the buffer layer are removed, the back electrode layer 112 and the transparent conductive layer 115 form a contact interface A. Step S08: Perform a third patterning process P3 for separating two adjacent battery cells 100. In this manner, the thin film solar cell 200 including a plurality of battery cells 100 connected in series can be formed, and when the sunlight is irradiated, the current path I is formed in the thin film solar cell 200.

According to the prior art, the first patterning process P1 is generally performed by laser for separating the back electrode layer 112, and the second patterning process P2 and the third patterning are performed by mechanical scribing using a tool. The program P3 is used to separate the absorption layer of the two adjacent battery cells from the buffer layer and the entire battery unit.

However, according to the prior art, the technique of removing the absorption layer and the buffer layer of the thin film solar cell unit 100 using a cutter, the resulting thin film solar cell sometimes has contact resistance due to the back electrode layer 112 and the transparent conductive layer 115. Too large, reducing the photoelectric conversion efficiency of the thin film solar cell. Therefore, it is necessary to further improve the manufacturing method of the conventional thin film solar cell to improve the photoelectric conversion efficiency of the thin film solar cell.

According to an embodiment of the invention, a method for fabricating a thin film solar cell includes a plurality of battery cells, the method comprising: forming a back electrode layer on a substrate; performing a first patterning process, using a Cutting the back electrode layer to form a back electrode of the battery cells separated from each other; forming an absorbing layer on the back electrode layer; forming a buffer layer on the absorbing layer; performing a second patterning process, utilizing Removing the absorbing layer and the buffer layer in a separation zone between two adjacent battery cells by mechanical scribing to separate the absorbing layer and the buffer layer of two adjacent battery cells, and then using another laser irradiation To the separation zone, the laser forms a trench, which is twice from the back electrode The surface of the formed layer extends downward by a predetermined depth H. (0<H≦ back electrode + secondary formation); forming a transparent conductive layer on the buffer layer and causing the back electrode layer in the separation region (in one embodiment, more specifically, back) The front and side edges of the electrode layer are in contact with the transparent conductive layer to form a contact interface; and a third patterning process is performed to separate the two adjacent battery cells.

In one embodiment, in the step of performing the second patterning process, the other laser forms a trench extending downward from the surface of the back electrode layer by a predetermined depth H.

In one embodiment, the back electrode layer is a molybdenum (Mo) metal layer.

In one embodiment, the step of forming an absorber layer on the back electrode layer forms a secondary formation layer in the back electrode layer.

In one embodiment, the transparent conductive layer is a GZO, BZO, ITO or AZO layer.

According to an embodiment of the present invention, in the second patterning process, the absorption layer and the buffer layer in a separation zone between two adjacent battery cells are removed by mechanical scribing, and then irradiated to separate by a laser. And the groove formed by the laser has a predetermined depth H. (0<H≦ back electrode + secondary formation). In this way, the secondary formation layer in the back electrode layer can be reduced, thereby reducing the contact resistance between the back electrode layer and the transparent conductive layer, thereby increasing the efficiency of the thin film solar cell.

100‧‧‧ battery unit

111‧‧‧Substrate

112‧‧‧ Back electrode layer

113‧‧‧absorbing layer

114‧‧‧buffer layer

115‧‧‧Transparent conductive layer

200‧‧‧Thin solar cells

300‧‧‧ battery unit

311‧‧‧Substrate

312‧‧‧ Back electrode layer

313‧‧‧Absorbent layer

314‧‧‧buffer layer

315‧‧‧Transparent conductive layer

316‧‧‧Secondary formation

400‧‧‧Thin film solar cells

Figure 1 shows a schematic diagram of a cell in a conventional thin film solar cell.

Figure 2 shows a schematic of a conventional thin film solar cell.

Fig. 3 is a flow chart showing a method of manufacturing a thin film solar cell according to an embodiment of the present invention.

4 is a schematic view showing a cross section of a thin film solar cell according to an embodiment of the present invention.

Figure 5 is a cross-sectional view showing a thin film solar cell in the steps of an embodiment of the present invention.

Fig. 3 is a flow chart showing a method of manufacturing a thin film solar cell according to an embodiment of the present invention. 4 is a schematic view showing a cross section of a thin film solar cell according to an embodiment of the present invention. As shown in FIG. 3 and FIG. 4, according to an embodiment of the invention, a method for fabricating a thin film solar cell is provided, wherein the thin film solar cell comprises a plurality of battery cells and in one embodiment it may be copper indium gallium selenide solar energy. A battery, and the method comprises the following steps.

Step S12: forming a back electrode layer 312 on a substrate 311. For example, a layer of molybdenum metal may be deposited as the back electrode layer 312.

Step S14: performing a first patterning process of cutting the back electrode layer 312 by laser to form the back electrodes of the battery cells 300 separated from each other.

Step S16: forming an absorbing layer 313 on the back electrode layer 312. In an embodiment, the absorbing layer 313 can be a copper indium gallium selenide layer.

Step S18: forming a buffer layer 314 on the absorption layer 313. In an embodiment, the buffer layer 314 can be a cadmium sulfide layer.

Step S20: performing a second patterning process of removing the absorption layer 313 and the buffer layer 314 in a separation area Sa between two adjacent battery cells 300 by mechanical scribing to obtain two adjacent battery cells 300. The absorbing layer 313 and the buffer layer 314 are separated, and then irradiated to the separation region Sa by a laser, and the trench formed by the laser has a predetermined depth H. (0<H≦ back electrode + secondary formation).

Step S22: forming a transparent conductive layer 315 on the buffer layer 314. At this time, in the separation region Sa in which the absorption layer is removed, the back electrode layer 312 and the transparent conductive layer 315 form a contact interface Sc. For example, it can be deposited A GZO, BZO, ITO or AZO layer is used as the transparent conductive layer 315.

Step S24: Perform a third patterning process for separating the two adjacent battery cells 300. In this manner, the thin film solar cell 400 including a plurality of battery cells 300 connected in series can be formed, and when the sunlight is irradiated, the current path I is formed in the thin film solar cell 400.

According to the applicant's experiment, the above manufacturing method can reduce the contact resistance between the back electrode layer 312 and the transparent conductive layer 315 while maintaining good product manufacturing yield. The reason for the applicant will be described in detail below.

Referring to FIGS. 3 and 4, after forming an absorbing layer 313 on the back electrode layer 312 in the foregoing step S06, since the elements in the absorbing layer 313 easily penetrate into the back electrode layer 312, and in the back electrode layer 312. A secondary formation layer 316 is formed in the middle. In an embodiment, the secondary formation layer 316 can be, for example, a MoSe layer or a MoS layer.

According to the prior art, when the absorbing layer 113 and the buffer layer 114 are mechanically removed using a cutter, it is difficult to completely remove the secondary formation layer 316. Since the resistance of the secondary formation layer 316 is higher than that of the back electrode layer, the contact resistance between the back electrode layer 312 and the transparent conductive layer 315 is increased, and the efficiency of the thin film solar cell 400 is lowered.

In order to solve this problem, the applicant has tried various solutions, such as the solution to control the force of the tool. Specifically, the removal force of the tool to the secondary formation layer 316 is increased. According to experiments, the removal ability of the tool for the secondary formation layer 316 is small, and if the force used is too large, the battery unit 300 is damaged, which causes a decrease in manufacturing yield.

Applicants have also attempted to increase the number of scribing times to thin the secondary formation layer to reduce the contact resistance between the back electrode layer 312 and the transparent conductive layer 315. However, its effect is not good and it will also affect the speed of production.

In one embodiment, the predetermined depth H is greater than the film thickness of the secondary formation layer 316. Thereby, the transparent conductive layer 315 is directly in contact with the uncontaminated back electrode layer 312.

In summary, according to an embodiment of the present invention, in the second patterning process, the absorbing layer 313 and the buffer layer in a separation region Sa between two adjacent battery cells 300 are removed by mechanical scribing in a second patterning process. After 314, a laser is used to illuminate the separation zone Sa, and the trench formed by the laser has a predetermined depth H. (0<H≦ back electrode + secondary formation). It should be understood that, in an embodiment, the size of the preset depth H may not be limited as long as the thickness of the second formation layer 316 is sufficient. Since the secondary formation layer 316 in the back electrode layer 312 is reduced, the contact resistance between the back electrode layer 312 and the transparent conductive layer 315 can be reduced, and the efficiency of the thin film solar cell 400 is increased.

300‧‧‧ battery unit

311‧‧‧Substrate

312‧‧‧ Back electrode layer

313‧‧‧Absorbent layer

314‧‧‧buffer layer

315‧‧‧Transparent conductive layer

316‧‧‧Secondary formation of the back electrode layer

400‧‧‧Thin film solar cells

Claims (6)

A manufacturing method for reducing series resistance of a thin film solar cell, the thin film solar cell comprising a plurality of battery cells, the method comprising: forming a back electrode layer on a substrate; performing a first patterning process, cutting the back electrode by using a laser a layer to form a back electrode of the battery cells separated from each other; forming an absorbing layer on the back electrode layer; forming a buffer layer on the film layer; performing a second patterning process, using a mechanical scribe line In one aspect, the absorbing layer and the buffer layer in a separation region between two adjacent battery cells are removed to separate the absorbing layer and the buffer layer of two adjacent battery cells, and then irradiated to the separation region by another laser to Forming a trench; forming a transparent conductive layer on the buffer layer, filling the transparent conductive layer with the trench formed by the other laser, and causing the back in the trench in the separation region The electrode layer and the transparent conductive layer are in contact to form a contact interface; and a third patterning process is performed to separate the two adjacent battery cells. The method of manufacturing a thin film solar cell according to claim 1, wherein in the step of performing the second patterning process, the trench formed by the other laser is from the surface of the secondary electrode formation layer Extending a predetermined depth H downward. The method of manufacturing a thin film solar cell according to claim 1, wherein the irradiation area of the other laser is less than or equal to the area of the separation region. The method of manufacturing a thin film solar cell according to claim 2, wherein the back electrode layer is molybdenum (Mo) metal layer. The method of manufacturing a thin film solar cell according to claim 4, wherein the step of forming an absorbing layer on the back electrode layer further forms a secondary formation layer in the back electrode layer, and the predetermined depth H is greater than 0 and less than or equal to the thickness of the back electrode and the secondary formation. The method of manufacturing a thin film solar cell according to claim 2, wherein the transparent conductive layer is gallium-doped zinc oxide (GZO), boron-doped zinc oxide (BZO), indium tin oxide (ITO) or aluminum-doped oxidation. Zinc (AZO) layer.