TWI398958B - Solar cell and method for manufacturing the same - Google Patents

Description

Solar cell and method of manufacturing same

The present invention relates to a solar cell and a method of fabricating the same, and more particularly to a solar cell capable of producing a larger amount of current and a method of manufacturing the same.

Figure 1 shows a cross-sectional view of a conventional solar cell. As shown in FIG. 1 , the conventional solar cell 100 includes a twin crystal substrate 110, an anti-reflection layer 120, and an electrode structure 130.

The twin substrate 110 includes an N-type region 111 and a P-type region 112 interconnected. In one embodiment, the twinned substrate 110 can be a P-type polycrystalline germanium substrate, and an N-type impurity, such as phosphorus or arsenic, is doped on one surface thereof to diffuse into the P-type polycrystalline germanium substrate to form an N-type impurity diffusion region. . As such, the N-type impurity diffusion region is the N-type region 111; and the remaining portion of the twin crystal substrate 110 forms the P-type region 112. The anti-reflective layer 120 may comprise a layer of tantalum nitride (Si ₃ N ₄ ). The electrode structure 130 includes two first electrodes 131 electrically connected to the N-type region 111; and a second electrode 132 electrically connected to the P-type region 112. The first electrode 131 and the second electrode 132 can be electrically connected to each other through a load 150 to form a current loop for supplying power to the load 150.

However, in the process of fabricating the conventional solar cell 100, in the step of doping the N-type impurity, in addition to forming the N-type region 111, an electrically connected N-type region 111 and the first layer are easily formed on the side of the twin crystal substrate 110. The leakage current path 116 of the two electrodes 132 causes the electrons e1 to flow from the N-type region 111 to the second electrode 132 directly through the leakage current path 116 without passing through the load 150. In addition, when the solar cell 100 is reversely biased, a leakage path is formed, which not only causes a decrease in conversion efficiency, but also causes a hot spot phenomenon to occur when the module factory uses the solar cell 100 having an excessively high reverse current.

In order to avoid the above problem, the conventional solar cell 100 performs edge isolation processing, that is, at a predetermined distance H from the edge of the twin crystal substrate 110, a separation trench 140 is formed, and the opening of the separation trench 140 is located at the receiving The surface of the sunlight extends toward the inside of the twin crystal substrate 110 to cut off a current path from the N-type region 111 to the second electrode 132, so that the electrons e2 can pass only the first electrode 131 and a load. Flows to the second electrode 132.

It is an object of an embodiment of the present invention to provide a solar cell capable of increasing the amount of current produced. An object of an embodiment is to provide a solar cell in which the separation trench is not formed on the surface facing the sunlight.

According to an embodiment of the invention, a solar cell is provided for converting a light into an electrical energy, comprising a twinned substrate, a first electrode, a second electrode, and a first separation trench. The twin crystal substrate has a first surface, a second surface, a first type region and a second type region. The first surface is for facing the light. The second surface is opposite the first surface. The first type region is adjacent to the first surface. The second type region is adjacent to the second surface and connects the first type region to form a connection interface between the first surface and the second surface. The first electrode is electrically connected to the first type region. The second electrode is electrically connected to the second type region. The first separation trench has a first opening on the second surface and extends toward the inside of the twin crystal substrate to cut off a current path of electrons flowing from the first type region to the second electrode. Preferably, the first separation channel passes through the connection interface.

In order to manufacture the solar cell of the above embodiment, according to an embodiment of the present invention, a solar cell manufacturing method includes: irradiating a second surface of a twin crystal substrate of a solar cell in which the separation trench is not formed by using a laser to form a direction A separation trench extending inside the twin crystal substrate is used to cut off a current path of electrons flowing from the first type region to the second electrode.

According to an embodiment of the invention, a solar cell is provided for converting a light into an electrical energy, comprising a twinned substrate, a first electrode, a second electrode, and a first separation trench. The twin crystal substrate has a first surface, a second surface, a first side, a first type region and a second type region. The first surface is for facing the light. The second surface is opposite the first surface. The first side connects the first surface and the second surface. The first type region is adjacent to the first surface. The second type region is adjacent to the second surface and connects the first type region to form a connection interface between the first surface and the second surface. The first electrode is electrically connected to the first type region. The second electrode is electrically connected to the second type region. The first separation trench has a first opening on the first side and extends toward the inside of the twinned substrate to cut off a current path from the first type region to the second electrode. In an embodiment, the first opening may be located between the first surface and the connection interface, or may be located between the second surface and the connection interface, or may be located at a portion of the connection interface of the first side. Preferably, the first separation channel passes through the connection interface.

In order to manufacture the solar cell of the above embodiment, according to an embodiment of the present invention, a solar cell manufacturing method includes: irradiating a first side of a twin crystal substrate of a solar cell in which the separation trench is not formed by using a laser to form a direction A separation trench extending inside the twin crystal substrate is used to cut off a current path of electrons flowing from the first type region to the second electrode.

As described above, since the separation trench of the solar cell according to an embodiment of the present invention is not formed on the surface facing the sunlight, an ineffective region is not formed, so that it can generate more current than the conventional solar cell. The amount of current that can be produced.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein. The above and other objects, features, and advantages of the invention will be apparent from

2 shows a cross-sectional view of a solar cell in accordance with an embodiment of the present invention. As shown in FIG. 2, the solar cell 200 includes a twinned substrate 210, an anti-reflective layer 220, and an electrode structure 230. The twin substrate 210 has a first surface 213, a second surface 214, an N-type region 211, a P-type region 212, and a separation trench 240.

The first surface 213 is for facing a light. The second surface 214 is opposite the first surface 213. The N-type region 211 is adjacent to the first surface 213. The P-type region 212 is adjacent to the second surface 214 and connects the N-type region 211 to form a connection interface 215 between the first surface 213 and the second surface 214. In one embodiment, the twinned substrate 210 can be a P-type polycrystalline germanium substrate, and a first surface 213 thereof is doped with an N-type impurity, such as phosphorus or arsenic, to diffuse into the P-type polycrystalline germanium substrate to form an N-type. Impurity diffusion zone. As such, the N-type impurity diffusion region is the N-type region 211; and the remaining portion of the twin crystal substrate 210 forms the P-type region 212. The anti-reflection layer 220 may be a tantalum nitride (Si ₃ N ₄ ) layer. The electrode structure 230 includes two first electrodes 231 electrically connected to the N-type region 211, and a second electrode 232 electrically connected to the P-type region 212. The first electrode 231 and the second electrode 232 can be electrically connected to each other through a load 250 to form a current loop for supplying power to the load 250.

The separation trench 240 has an opening 241 on the second surface 214 and extends toward the inside of the twine substrate 210 for cutting off a leakage current path 216 from the N-type region 211 to the second electrode 232. In order to further ensure that the separation trench 240 can substantially cut off the aforementioned leakage current path 216, it is preferred that the separation trench 240 pass through the connection interface 215.

In one embodiment, the step of forming the separation trench of the solar cell manufacturing method may include: irradiating the second surface 214 with a laser to form a separation trench 240 extending toward the inside of the twinned substrate 210. In the present embodiment, the laser can use a yttrium aluminum garnet (Nd: YAG) laser. When the Nd:YAG laser illuminates the surface of the object, the surface of the object is vaporized by the high energy of the laser beam, and the room temperature becomes particles, since the Nd:YAG laser is directed toward the inside of the twinned substrate 210, and the second is irradiated. The surface 214 can thus form a separation trench 240 in which the opening 241 is located on the second surface 214 and extends toward the inside of the twinned substrate 210.

Further, when the depth of the separation groove 240 is to reach the extent of passing through the connection interface 215, the etching time required for etching by laser is long. Therefore, in an embodiment, a separation groove may also be formed from the side of the twin crystal substrate 210.

3A shows a cross-sectional view of a solar cell in accordance with an embodiment of the present invention. The solar cell 200a of the embodiment of FIG. 3A is similar to the solar cell 200 of the embodiment of FIG. 2, and therefore, the same components are denoted by the same reference numerals in the following description, and the related description will be omitted, and only the differences will be described. As shown in FIG. 3A, the separation trench 240a of the solar cell 200a has an opening 241a on the first side surface 217 and extends toward the inside of the twin crystal substrate 210 for cutting off an electron from the N-type region 211 to the second electrode 232. Current path. Since the step of doping the N-type impurity is to dope the first surface 213, the leakage current path 113 of the portion of the first surface 213 is thicker, and the opening 241a is located at the separation trench 240a of the first side surface 217, and the depth can be designed. It is smaller than the depth of the separation groove 240 of the embodiment of Fig. 2. Furthermore, a further separation groove 240a may be formed on the second side surface 218 of the twinned substrate 210 relative to the first side surface 217, and may be identical to the separation groove 240a formed on the first side surface 217, so that the following A description of another separation groove 240a will be omitted.

In an embodiment, the step of forming the separation trench 240a in the solar cell manufacturing method may include: aiming at a portion of the connection interface 215 of the first side surface 217 in a direction perpendicular to the first side surface 217 by using a laser, and irradiating the portion A side surface 217 is formed to form a separation groove 240a extending toward the inside of the twin crystal substrate 210. In the present embodiment, the opening 241a of the separation groove 240a is located at a portion of the connection interface 215 of the first side surface 217, and extends toward the inside of the twin crystal substrate 210 in a direction perpendicular to the first side surface 217. Therefore, the separation groove 240 has passed through the connection interface 215, and it is possible to further ensure that the separation groove 240 substantially cuts off the leakage current path 216. Further, since the separation groove 240a extends in the direction perpendicular to the first side surface 217, the leakage current path 216 can be cut at a short depth. It should be understood that the present invention is not limited to the above features, and the separation groove may be formed as described later.

3B and 3C are cross-sectional views showing a solar cell according to an embodiment of the present invention. The solar cells 200b and 200c of the embodiment of FIGS. 3B and 3C are similar to the solar cell 200a of the embodiment of FIG. 3A. Therefore, in the following description, the same components are denoted by the same reference numerals, and the description thereof will be omitted, and only the differences will be described.

As shown in FIG. 3B, in an embodiment, the step of forming the separation trench 240b in the solar cell manufacturing method may include: using a laser to be tilted in the direction of the first side surface 217 and toward the second surface 214, The first surface 213 of the first side surface 217 and the portion between the connection interfaces 215 illuminate the first side surface 217 to form a separation trench 240b extending toward the inside of the twin crystal substrate 210. In the present embodiment, the opening 241b of the separation groove 240b is located at a portion between the first surface 213 of the first side surface 217 and the connection interface 215. In order to further ensure that the separation trench 240b can substantially cut off the aforementioned leakage current path 216, it is preferable that the separation trench 240b passes through the connection interface 215.

As shown in FIG. 3C, in an embodiment, the step of forming the separation trench 240c in the solar cell manufacturing method may include: using a laser to be tilted in the direction of the first side surface 217 and facing the first surface 213, The second surface 214 of the first side surface 217 and the portion between the connection interfaces 215 illuminate the first side surface 217 to form a separation groove 240c extending toward the inside of the twin crystal substrate 210. In the present embodiment, the opening 241c of the separation groove 240c is located at a portion between the second surface 214 of the first side surface 217 and the connection interface 215. In order to further ensure that the separation groove 240c can substantially cut off the aforementioned leakage current path 216, it is preferable that the separation groove 240c passes through the connection interface 215.

Referring to FIG. 1 and FIG. 2 again, since the separation trench 140 of the conventional solar cell 100 is formed on the first surface 213 facing the sunlight, although the separation trench 140 can cut off the leakage current, the edge of the twinned substrate 110 is The predetermined distance H portion becomes an ineffective area, and the current that the solar cell 100 can produce is reduced. In contrast, the separation trench 240 of the solar cell 200 is formed on the second surface 214 of the twinned substrate 110 that is not facing the sunlight, so that the entire first surface 213 is an effective region for enabling the current generated by the solar cell 200. More current than the conventional solar cell 100 can produce. As described above, since the separation grooves of the solar cells 200a, 200b, and 200c are not formed on the first surface 213 facing the sunlight, they can generate more current than the conventional solar cell 100 can produce.

The amount of increased current is further estimated below. 4 shows a top view of a conventional twinned substrate formed with a first electrode. As shown in FIG. 4, the first electrode 113 includes a finger electrode 113a and a bus bar wiring 113b. The ineffective area S formed after the edge isolation treatment of the first surface. In general, there are a total of 65 finger electrodes 113a having a line width of 100 um. There are two bus bar wirings 113b, and the line width is 1.8 mm. The predetermined distance H of the separation trench 140 from the edge of the twinned substrate 110 is 200 um. Therefore, the area of the area where the photocurrent can be effectively supplied is 24336 m ^{2 -} 1551.1 mm ² -124.8 mm ² = 22660 mm ² . Electrical parameters Isc = 8.16 (A), Voc = 0.621 (V), FF = 0.77, and photoelectric conversion efficiency Eff. = 16.03%.

In contrast, in an embodiment of the present invention, since the separation trench is not formed on the surface facing the sunlight, the ineffective region S is not generated, and therefore, under the same conditions, the area of the photocurrent effective to provide the area is 24336 m ² - 1551.1mm ² = 22784.8mm ² . Since the area of the area where the photocurrent can be effectively supplied has increased, it is estimated that the electrical parameter Isc can be increased to 8.16*(1+(22784.8-22660)/22660)=8.20(A). When Isc = 8.16 (A), and Voc = 0.621 (V) and FF = 0.77 are all the same, the photoelectric conversion efficiency Eff. = 16.11%. Therefore, it can be inferred from the above that the photoelectric conversion efficiency is increased by about 0.1%.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

100. . . Solar battery

110. . . Twin crystal substrate

111. . . N-type area

112. . . P-type area

116. . . Leakage current path

120. . . Antireflection layer

130. . . Electrode structure

131. . . First electrode

132. . . Second electrode

140. . . Separation ditch

150. . . load

200. . . Solar battery

200a. . . Solar battery

200b. . . Solar battery

200b. . . Solar battery

200c. . . Solar battery

210. . . Twin crystal substrate

211. . . N-type area

212. . . P-type area

213. . . First surface

214. . . Second surface

215. . . Connection interface

216. . . Leakage current path

217. . . First side

218. . . Second side

220. . . Antireflection layer

230. . . Electrode structure

231. . . First electrode

232. . . Second electrode

240. . . Separation ditch

240a. . . Separation ditch

240b. . . Separation ditch

240c. . . Separation ditch

241. . . Opening

241a. . . Opening

241b. . . Opening

241c. . . Opening

250. . . load

E1. . . electronic

E2. . . electronic

Figure 1 shows a cross-sectional view of a conventional solar cell.

2 shows a cross-sectional view of a solar cell in accordance with an embodiment of the present invention.

3A to 3C are cross-sectional views showing a solar cell according to an embodiment of the present invention.

4 shows a top view of a conventional twinned substrate formed with a first electrode.

200‧‧‧ solar cells

210‧‧‧Crystal substrate

211‧‧‧N-type area

212‧‧‧P type area

213‧‧‧ first surface

214‧‧‧ second surface

215‧‧‧ Connection interface

216‧‧‧Leakage current path

220‧‧‧Anti-reflective layer

230‧‧‧Electrode structure

231‧‧‧First electrode

232‧‧‧second electrode

240‧‧‧Separation ditch

241‧‧‧ openings

250‧‧‧load

E1‧‧‧Electronics

E2‧‧‧Electronics

Claims (13)

A solar cell for converting a light into an electric energy, comprising: a twin crystal substrate having: a first surface for facing the light; a second surface opposite to the first surface; a first type region Close to the first surface; and a second type region adjacent to the second surface, and connecting the first type region to form a connection interface between the first surface and the second surface; a first electrode, Electrically connecting the first type region; a second electrode electrically connecting the second type region; and a first separation trench having a first opening on the second surface and extending toward the inside of the twin crystal substrate for A current path that flows from the first type region to the second electrode is cut off. The solar cell of claim 1, wherein the first separation trench further passes through the connection interface. The solar cell of claim 1, further comprising a second separation trench having a second opening on the second surface relative to the first separation trench and extending toward the inside of the twin crystal substrate And cutting a current path from the first type region to the second electrode. The solar cell of claim 1, wherein the first type region is an N-type impurity diffusion region; and the second region is a P-type polysilicon region. The solar cell of claim 1, further comprising an anti-reflection layer on the first type region. A solar cell for converting a light into an electrical energy, comprising: a twinned substrate having: a first surface for facing the light; a second surface opposite the first surface; a first side, Connecting the first surface and the second surface; a first type region adjacent to the first surface; and a second type region adjacent to the second surface and connecting the first type region to form the first surface And a connection interface between the second surface; a first electrode electrically connected to the first type region; a second electrode electrically connected to the second type region; and a first separation groove having a first opening The first side extends toward the inside of the twin crystal substrate to cut off a current path of electrons flowing from the first type region to the second electrode. The solar cell of claim 1, wherein the first opening is located between the first surface and the connection interface. The solar cell of claim 1, wherein the first opening is located between the second surface and the connection interface. The solar cell of claim 1, wherein the first opening is located at a portion of the connection interface of the first side. The solar cell of any one of claims 6 to 9, wherein the first separation trench further passes through the connection interface. The solar cell of claim 1, wherein the twin crystal substrate further has a second side opposite to the first side and connecting the first surface and the second surface; the solar cell further comprises a first The two separation trenches have a second opening on the second side and extend toward the inside of the twin crystal substrate for cutting another current path from another first type region to the second electrode. A solar cell manufacturing method, comprising: a twin crystal substrate, having: a first surface for facing the light; a second surface opposite to the first surface; a first type region, adjacent to the first a surface; and a second type region adjacent to the second surface, and connecting the first type region to form a connection interface between the first surface and the second surface; a first electrode electrically connecting the first a first type region; and a second electrode electrically connected to the second type region, the solar cell manufacturing method comprising: illuminating the second surface with a laser to form a separation trench extending toward the inside of the twin crystal substrate A current path that flows from the first type region to the second electrode is cut off. A solar cell manufacturing method, comprising: a twin crystal substrate, having: a first surface facing the light; a second surface opposite to the first surface; a first side connecting the first a surface and the second surface; a first type region adjacent to the first surface; and a second type region adjacent to the second surface and connecting the first type region to form the first surface and the second surface a connection interface between the surfaces; a first electrode electrically connected to the first type region; and a second electrode electrically connected to the second type region, the solar cell manufacturing method comprising: illuminating the first side with a laser And forming a separation trench extending into the interior of the twin crystal substrate for cutting a current path of electrons flowing from the first type region to the second electrode.