TW201801332A - Single-sided solar cell, method for manufacturing the same and solar cell module - Google Patents

Abstract

A single-sided solar cell includes a substrate, a first passivation layer, a second passivation layer, a front electrode and a rear electrode. The substrate has a front side and a rear side. The substrate includes an emitter layer disposed on the front side, and a back surface field layer disposed on the rear side. The first passivation layer and the second passivation layer respectively cover the front side and the rear side. The second passivation layer has a plurality of holes exposing a portion of the back surface field layer. The front electrode is disposed on the front side. The rear electrode is disposed on the rear side, and the rear electrode includes a plurality of first electrodes, a second electrode and a plurality of bus electrodes. The first electrodes are respectively disposed in the holes and contact with the rear side, the second electrode covers the second passivation layer and correspondingly covers a scope around the rear side, the second electrode covers the first electrodes, a material of the first electrodes is different from that of the second electrode, and the bus electrodes are arranged on the rear side and contact with the second electrode.

Description

Single-sided light-receiving solar cell and manufacturing method thereof Solar battery module

The present invention relates to a photoelectric conversion device, and more particularly to a single-sided light-receiving solar cell and a method of fabricating the same.

The current solar cells have a single-sided light-input structure and a double-sided light-integrated structure. Please refer to FIG. 1 , which is a cross-sectional view showing a conventional double-sided light-emitting solar cell. The double-sided light-emitting solar cell 100 mainly includes a substrate 102, an emitter layer 104, a passivation layer 106, a back surface electric field layer 108, a passivation layer 110, a first electrode 112, and a second electrode 114. The substrate 102 includes a first side 116 and a second side 118 opposite each other. The first surface 116 and the second surface 118 of the substrate 102 can be roughened to have rough structures 120 and 122, respectively, to enhance the light absorption efficiency of the solar cell 100.

The emitter layer 104 is disposed in the substrate 102 at a position close to the first surface 116. The emitter layer 104 has a different electrical property than the substrate 102. A passivation layer 106 is disposed on the first side 116 and contacts the emitter layer 104 to passivate the first side 116 of the substrate 102. The first electrode 112 is disposed above the first surface 116 of the substrate 102, and the first electrode 112 can pass through the passivation layer 106 to contact the emitter layer 104 of the first surface 116, thereby forming an electrical connection.

The back surface electric field layer 108 is disposed in the substrate 102 at a position close to the second surface 118. The back side electric field layer 108 has the same electrical properties as the substrate 102. A passivation layer 110 is disposed on the second side 118 and contacts the back surface field layer 108 to passivate the second side 118 of the substrate 102. The second electrode 114 is disposed on the second surface 118 of the substrate 102, and the second electrode 114 can pass through the passivation layer 110 to contact the back surface electric field layer 108 of the second surface 118, thereby forming an electrical connection.

In general, double-sided light-emitting solar cells are more efficient than single-sided solar cells, and should be considered more important. However, since the module architecture development of the previous module vendors is aimed at single-sided solar cells, and the demand for double-sided light-emitting solar cells is low, the current research and development is still single-sided. Solar cells are the mainstay.

Please refer to FIG. 2 , which is a cross-sectional view showing a conventional single-sided light-emitting solar cell. The single-sided light-emitting solar cell 200 mainly includes a substrate 202, an emitter layer 204, a passivation layer 206, a back surface electric field layer 208, a passivation layer 210, a first electrode 212, and a second electrode 214. The substrate 202 includes a first side 216 and a second side 218 opposite each other. The first side 216 of the substrate 202 can likewise be roughened to have a rough structure 220.

The emitter layer 204 is disposed in the substrate 202 at a position close to the first surface 216. The emitter layer 204 has a different electrical property than the substrate 202. The passivation layer 206 is disposed on the first face 216 and contacts the emitter layer 204. The first electrode 212 is disposed above the first surface 216 of the substrate 202, and the first electrode 212 can pass through the passivation layer 206 to contact the emitter layer 204 of the first surface 216, thereby forming an electrical connection.

The back surface electric field layer 208 is disposed in the substrate 202 at a position close to the second surface 218. The back side electric field layer 208 has the same electrical properties as the substrate 202. The passivation layer 210 is disposed on the second face 218 and contacts the back surface electric field layer 208 to passivate the second face 218 of the substrate 202. A plurality of openings 222 are formed in the passivation layer 210 exposing the back surface electric field layer 208, wherein the openings 222 are formed by ablation of the passivation layer 210 by a laser perforation process. These openings 222 expose a portion of the back side electric field layer 208. The second electrode 214 is disposed on the second surface 218 of the substrate 202 and covers the passivation layer 210 and is disposed in the openings 222 of the passivation layer 210 to contact the back surface electric field layer 208 to form an electrical connection.

When the solar cell 200 is fabricated, the opening 222 is formed by ablation of the passivation layer 210 by a laser perforation process, and the laser easily damages the second side 218 of the substrate 202, thereby causing the open circuit voltage (Voc) of the solar cell 200 to decrease. . In addition, the laser perforation process is expensive and time consuming, resulting in increased process costs and reduced throughput.

Accordingly, it is an object of the present invention to provide a single-sided light-receiving solar cell, a method of fabricating the same, and a solar cell module, the back electrode comprising a first electrode passing through the passivation layer, and covering the passivation layer and at least a portion thereof a second electrode on the first electrode. The first electrode may be made of a material having a lower resistivity than the second electrode, so that the current conduction of the first electrode can be effectively improved, so that the solar cell has high efficiency. In addition, current collection and light reflection of the second electrode can cause the solar cell to have a high fill factor (FF) and a high short circuit current (Jsc).

Another object of the present invention is to provide a single-sided light-receiving solar cell, a method of manufacturing the same, and a solar cell module, wherein a first electrode of a back electrode has a composition that can burn through the passivation layer during sintering with respect to the second electrode. Therefore, the first electrode can be passed through the passivation layer by means of sintering. Compared with the conventional laser perforation method, the sintering method can reduce the damage to the back surface of the substrate, and can increase the open circuit voltage of the solar cell. In addition, the use of sintering methods can reduce process costs and increase production capacity.

According to the above object of the present invention, a single-sided light-receiving solar cell is proposed. The single-sided light-receiving solar cell includes a substrate, a first passivation layer and a second passivation layer, a front electrode, and a back electrode. The substrate has a front side and a back side, wherein the substrate includes an emitter layer disposed on the front surface and a back surface electric field layer disposed on the back surface. The first passivation layer and the second passivation layer respectively cover the front side and the back side, wherein the second passivation layer has a plurality of open-hole exposed portions of the back surface electric field layer. The front electrode is on the front side. The back electrode is located on the back surface, and the back electrode comprises a plurality of first electrodes, a second electrode and a plurality of bus electrodes, wherein the first electrodes are respectively disposed in the openings and contact the back surface, and the second electrode covers the second passivation layer And correspondingly covering the range around the back surface, the second electrode covers the first electrode, the plurality of first electrodes are different from the material of the second electrode, and the plurality of bus electrodes are arranged at the back surface and are in contact with the second electrode .

According to an embodiment of the invention, the plurality of first electrodes have a composition that can burn through the second passivation layer during sintering with respect to the second electrode.

According to an embodiment of the invention, the material of the first electrode comprises a group consisting of silver and copper, and the material of the second electrode comprises a group consisting of aluminum and copper.

According to an embodiment of the invention, the opening is a dot shape, a dotted line shape or a linear shape.

According to an embodiment of the invention, each of the first electrodes is completely covered or partially covered by the second electrode.

According to the above object of the present invention, a solar battery module is further proposed. The solar cell module comprises an upper plate, a lower plate, a single-sided light-receiving solar cell as described above, and at least one encapsulating material layer. A single-sided light-receiving solar cell is disposed between the upper plate and the lower plate. The encapsulating material layer is located between the upper plate and the lower plate, and the single-sided light-receiving solar cell is combined with the upper plate and the lower plate.

According to the above object of the present invention, a method of manufacturing a single-sided light-receiving solar cell is further proposed. In this method, a substrate is provided having a front side and a back side. The emitter layer and the back surface electric field layer are formed on the front side and the back side, respectively. The first passivation layer and the second passivation layer are formed to cover the front side and the back side, respectively. The front electrode and the back electrode are respectively formed on the front surface and the back surface, and the back electrode includes a plurality of first electrodes, a second electrode and a plurality of bus electrodes. Forming the plurality of first electrodes, the second electrodes, and the plurality of bus electrodes, comprising: providing a plurality of first electrode pastes and a plurality of bus electrode pastes on the second passivation layer, wherein each of the first electrode pastes Each of the bus electrode pastes has a different area covered by each other. Providing a second electrode paste on the second passivation layer, the material of the plurality of second electrode pastes is different from the material of the first electrode paste and the plurality of bus electrode pastes, and the second electrode paste covers the second electrode paste Multiple first electrodes The slurry, the second electrode slurry is connected to the periphery of each of the bus electrode pastes, and the second electrode paste corresponds to a range around the back surface. Forming, by a sintering process, the plurality of first electrode pastes, the second electrode paste, and the plurality of bus electrode pastes to form the plurality of first electrodes, the second electrodes, and the plurality of bus electrodes, wherein the plurality of first electrodes An electrode paste and a plurality of bus electrode pastes are burned through the second passivation layer to form the plurality of openings, respectively, to contact the back surface, and the second electrode paste and the back surface are separated by the second passivation layer without contact The back.

According to an embodiment of the invention, the opening is a dot shape, a dotted line shape or a linear shape.

According to an embodiment of the invention, the material of the first electrode comprises a group consisting of silver and copper, and the material of the second electrode comprises a group consisting of aluminum and copper.

According to an embodiment of the invention, each of the first electrodes is completely covered or partially covered by the second electrode.

According to an embodiment of the invention, the plurality of first electrode pastes have a composition capable of burning through the second passivation layer, and the second electrode paste has no or less energy to burn through the second passivation layer. ingredient.

100‧‧‧ solar cells

102‧‧‧Substrate

104‧‧ ‧ emitter layer

106‧‧‧ Passivation layer

108‧‧‧Back electric field layer

110‧‧‧ Passivation layer

112‧‧‧First electrode

114‧‧‧second electrode

116‧‧‧ first side

118‧‧‧ second side

120‧‧‧Rough structure

122‧‧‧Rough structure

200‧‧‧ solar cells

202‧‧‧Substrate

204‧‧ ‧ emitter layer

206‧‧‧ Passivation layer

208‧‧‧Back surface layer

210‧‧‧ Passivation layer

212‧‧‧First electrode

214‧‧‧second electrode

216‧‧‧ first side

218‧‧‧ second side

220‧‧‧Rough structure

222‧‧‧ openings

300‧‧‧Solar battery module

302‧‧‧Single-sided solar cells

302a‧‧‧Single-sided solar cells

304‧‧‧Upper board

306‧‧‧ Lower board

308‧‧‧Package material layer

310‧‧‧Package material layer

312‧‧‧Substrate

312a‧‧‧Substrate

314‧‧‧First passivation layer

316‧‧‧second passivation layer

316a‧‧‧second passivation layer

316b‧‧‧second passivation layer

316c‧‧‧second passivation layer

318‧‧‧Front electrode

320‧‧‧Back electrode

322‧‧‧First electrode

324‧‧‧second electrode

326‧‧‧ positive

328‧‧‧Back

330‧‧‧Rough structure

332‧‧ ‧ emitter layer

334‧‧‧Back surface layer

336‧‧‧ openings

336a‧‧‧Opening

336b‧‧‧Opening

336c‧‧‧Opening

338‧‧‧Opening

338a‧‧‧Opening

338b‧‧‧Opening

338c‧‧‧Opening

340‧‧‧Concurrent electrode

342‧‧‧Selective back surface layer

400‧‧‧ steps

402‧‧‧Steps

404‧‧‧Steps

406‧‧‧Steps

408‧‧‧Steps

410‧‧‧Steps

412‧‧‧Steps

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing a conventional double-sided light-emitting solar cell; FIG. 2 is a schematic cross-sectional view showing a conventional single-sided light-emitting solar cell; FIG. 3 is a cross-sectional view showing a solar cell module according to an embodiment of the present invention; A schematic cross-sectional view of a single-sided light-receiving solar cell according to an embodiment of the present invention; [FIG. 5A] illustrates a second passivation layer of a single-sided light-receiving solar cell according to an embodiment of the present invention. The distributed intent of the hole; [Fig. 5B] is a schematic view showing the distributed intent of the opening in the second passivation layer of the solar cell with too single-sided light receiving light according to an embodiment of the present invention; [Fig. 5C] A distributed intent of an opening of a single-sided light-receiving solar cell according to an embodiment of the present invention; [FIG. 6] is a cross-sectional view showing a single-sided light-receiving solar cell according to an embodiment of the present invention; And [FIG. 7] is a flow chart showing the manufacture of a single-sided light-receiving solar cell according to an embodiment of the present invention.

Please refer to FIG. 3 , which is a cross-sectional view showing a solar cell module according to an embodiment of the present invention. In the present embodiment, the solar cell module 300 mainly comprises a single-sided light-receiving solar cell 302, an upper plate 304, a lower plate 306, and one or more layers of encapsulating material, such as ethylene-vinyl acetate copolymer (EVA). Encapsulation material layers 308 and 310.

As shown in FIG. 3, in the solar cell module 300, a single-sided light-receiving solar cell 302 is disposed on the lower plate 306 and disposed on the upper plate 304. under. Therefore, the upper plate 304 is disposed above the lower plate 306, and the single-sided light-receiving solar cell 302 is disposed between the lower plate 306 and the upper plate 304. In addition, the two layers of encapsulation material layers 308 and 310 are respectively disposed between the upper plate 304 and the single-sided light-receiving solar cell 302, and the lower plate 306 and the single-sided light-receiving solar cell 302. The encapsulating material layers 308 and 310 are used to bond the single-sided light-receiving solar cell 302 to the lower plate 306 and the upper plate 304 in a molten state by a high temperature press-fitting procedure.

Please refer to FIG. 4 , which is a cross-sectional view of a single-sided light-receiving solar cell according to an embodiment of the present invention. In some embodiments, the single-sided light-receiving solar cell 302 can primarily include a substrate 312, a first passivation layer 314, a second passivation layer 316, a front side electrode 318, and a back side electrode 320.

The substrate 312 has a front side 326 and a back side 328, and the front side 326 and the back side 328 are respectively located on opposite sides of the substrate 312. The substrate 312 can be of a first conductivity type. In some examples, the material of the substrate 312 can be a semiconductor material such as germanium. In some exemplary embodiments, the front side 326 of the substrate 312 may be roughened such that the front side 326 of the substrate 312 has a rough structure 330, such as a pyramidal structure of a single crystal wafer, thereby enhancing single-sided light-receiving solar energy. The absorption efficiency of the battery 302 for incident light.

The substrate 312 includes an emitter layer 332 and a back surface field layer 334. The emitter layer 332 can be disposed entirely within the substrate 312 and near the front side 326. The emitter layer 332 can be a doped layer within the substrate 312 and have a second conductivity type different from the substrate 312. For example, when the electrical property of the substrate 312 is N-type, the emitter layer 332 may be a P-type doped layer, such as boron (B), aluminum (Al), gallium. (Ga), indium (In) or germanium (Tl) doped layers. The back side electric field layer 334 can be disposed within the substrate 312 and near the back surface 328. The back surface electric field layer 334 has the same first conductivity type as the substrate 312. For example, when the electrical properties of the substrate 312 are N-type, the back surface electric field layer 334 can be an N-type doped layer formed on the back surface 328, such as a phosphorus doped layer.

The first passivation layer 314 can overlie the front side 326 of the substrate 312 and contact the emitter layer 332 to passivate the front side 326. In some examples, the material of the first passivation layer 314 may be tantalum oxide, tantalum nitride or aluminum oxide, and the first passivation layer 314 may be a single layer structure or a multilayer stack structure. The second passivation layer 316 can then overlie the back side 328 of the substrate 312 and contact the back surface field layer 334 to passivate the back side 328. The material of the second passivation layer 316 may be, for example, hafnium oxide, tantalum nitride or aluminum oxide, and the second passivation layer 316 may also be a single layer structure or a multilayer stack structure. The second passivation layer 316 has a plurality of openings 336 for a portion of the back electrode 320 to be disposed therein. The openings 336 extend through the second passivation layer 316 to expose a portion of the back surface field layer 334. In addition, the single-sided light-receiving solar cell 302 may include a plurality of bus electrodes 340, and the second passivation layer 316 may further have a plurality of openings 338 for the bus electrodes 340 to be arranged therein. The openings 336 in the second passivation layer 316 on the back side 328 of the single-sided light-receiving solar cell 302 can be of various types and arrangements. In some examples, the apertures 336 can be punctiform, dashed, or linear.

Referring to FIG. 5A, FIG. 5B and FIG. 5C, respectively, the distributed intentions of the openings in the second passivation layer of three solar cells according to an embodiment of the present invention are respectively illustrated. As shown in FIG. 5A, the second passivation layer 316a has three openings 338a for the bus electrode 340, and the three openings 338a are large. Parallel is disposed in the second passivation layer 316a. Further, the openings 336a are dot-like and are arranged in an array in the second passivation layer 316a. In some other examples, the dot-like openings 336a may be arranged in a triangular lattice or a rectangular lattice.

As shown in FIG. 5B, the second passivation layer 316b has three openings 338b for the bus electrode 340, and the three openings 338b are also disposed substantially in parallel in the second passivation layer 316b. Further, the opening 336b has a dotted line shape. In such an example, the openings 336b may be arranged in a second passivation layer 316b in a staggered manner between the upper and lower columns, and a portion of the opening 336b may traverse the opening 338b.

As shown in FIG. 5C, the second passivation layer 316c has three openings 338c for the bus electrodes 340, and the three openings 338c are also disposed substantially in parallel in the second passivation layer 316c. Further, the opening 336c is linear. In such an example, the openings 336c may be arranged in a substantially parallel manner in the second passivation layer 316c, and the openings 336c may traverse the openings 338c.

The front electrode 318 is disposed above the front side 326 of the substrate 312 and on the first passivation layer 314. The front electrode 318 can pass through the first passivation layer 314 to contact the emitter layer 332 of the front side 326 to form an electrical connection. The material of the front electrode 318 may include silver, aluminum, or silver aluminum alloy.

The back electrode 320 is disposed on the back surface 328 of the substrate 312. Referring again to FIG. 4, in some examples, the back electrode 320 can include a plurality of first electrodes 322 and a second electrode 324. The first electrodes 322 are respectively disposed in the openings 336 of the second passivation layer 316 and are in contact with the back surface 328 of the substrate 312 exposed by the openings 336, that is, the back surface electric field of the back surface 328. Layer 334 is in contact and electrically connected. The second electrode 324 covers the second passivation layer 316 and covers the area around the back surface 328, and the second electrode 324 covers the first electrode 322 and is in contact with the first electrode 322 to collect the first electrode. The current from 322. In some examples, as shown in FIG. 4, each of the first electrodes 322 is completely covered by the second electrode 324. In addition, the second electrode 324 does not completely cover the bus electrode 340, but only covers the periphery of the bus electrode 340, so that the bus electrode 340 is connected to a conductive strip (not shown). In other examples, each of the first electrodes 322 is partially covered by the second electrode 324. In some exemplary examples, without the opening 338, when the aperture ratio of the opening 336 in the second passivation layer 316 is from about 3% to about 4%, the single-sided light-receiving solar cell 302 can be preferably obtained. effectiveness.

In the back electrode 320, the first electrode 322 is primarily configured to transfer current in the back surface field layer 334 to the second electrode 324, while the second electrode 324 is used to collect these currents. In some examples, the first electrode 322 has a composition that can be burned through the second passivation layer 316 when sintered relative to the second electrode 324, so that the first electrode 322 forms an opening 336 in the second passivation layer 316 and is disposed on the first electrode 322. These openings 336 are in the middle. In some exemplary examples, the materials of the first electrode 322 and the second electrode 324 are different. For example, the material of the first electrode 322 comprises a group consisting of silver and copper, and the material of the second electrode 324 comprises a group consisting of aluminum and copper. In the example where the material of the first electrode 322 contains silver and the material of the second electrode 324 contains aluminum, since the silver has a high conductivity, the conduction efficiency of the current can be improved, and the single-sided light-receiving solar cell 302 can be improved. Efficiency; aluminum can collect current and reflected light, and is cheaper than silver, so that single-sided light-receiving solar cell 302 can have a high fill factor at a lower cost. With high short circuit current. In addition, in various embodiments of the present invention, the material of the bus electrode 340 may be the same as the material of the first electrode 322, but may be different, which may be selected according to different needs.

In addition, since the first electrode 322 has a component that can burn through the second passivation layer 316 at the time of sintering with respect to the second electrode 324, the first electrode 322 can be passed through the second passivation layer 316 by means of sintering. Since the sintering method is much less damage to the back surface 328 of the substrate 312 than the conventional laser perforation method, the open circuit voltage of the single-sided light-receiving solar cell 302 can be improved. Moreover, opening the hole in the second passivation layer 316 in a sintered manner can reduce the process cost and increase the productivity.

Please refer to FIG. 6 , which is a cross-sectional view of a single-sided light-receiving solar cell according to an embodiment of the present invention. In the present embodiment, the structure of the single-sided light-receiving solar cell 302a is substantially the same as that of the single-sided light-receiving solar cell 302. The difference between the two is mainly because the substrate 312a of the single-sided light-receiving solar cell 302a further includes A plurality of selective back surface electric field (S-BSF) layers 342 are provided on the back side 328. In some examples, the selective back surface field layer 342 and the first electrode 322 and the bus electrode 340 are respectively located on opposite sides of the back surface electric field layer 334, and the selective back surface electric field layer 322 corresponds to the first electrode 322 and the bus electrode, respectively. 340.

Please refer to FIG. 7 and FIG. 4 together. FIG. 7 is a flow chart showing the manufacture of a solar cell according to an embodiment of the present invention. In the present embodiment, when the single-sided light-receiving solar cell 302 shown in FIG. 4 is fabricated, the substrate 312 may be provided first, wherein the substrate 312 has a front side 326 and a back side 328 opposite to each other. The substrate 312 can be of a first conductivity type, and the substrate 312 The material can be a semiconductor material such as germanium. In some examples, the front side 326 of the substrate 312 may be roughened such that the front side 326 of the substrate 312 has a rough structure 330, such as a pyramidal topography.

Next, step 402 can be performed to form a second conductivity type emitter layer 332 on the front side 326, for example, by performing a doping process on the front side 326 of the substrate 312. The emitter layer 332 extends over the entire front side 326. In practice, the emitter layer 332 is disposed within the substrate 312 and adjacent the front side 326. The second conductivity type is different from the first conductivity type of the substrate 312, and the first conductivity type is an N type, and the second conductivity type is a P type. At this time, the emitter layer 332 may be a P-type doped layer such as boron (B), aluminum (Al), gallium (Ga), indium (In) or germanium (Tl) doped layers.

Next, step 404 can be performed to form a back surface electric field layer 334 of the first conductivity type on the back surface 328, for example, by performing a doping process on the back surface 328 of the substrate 312. The back surface field layer 334 extends over the entire back surface 328. In practice, the back surface field layer 334 can be disposed within the substrate 312 and adjacent the back surface 328. In some exemplary examples, the first conductivity type is N-type, and the back surface 328 may be doped using, for example, phosphorus oxychloride (POCl ₃ ), and thus the back surface electric field layer 334 may be a phosphorus doped layer. The exemplary embodiment of FIG. 7 is described in the order in which the emitter layer 332 is formed first and the back surface field layer 334 is formed. However, the present invention is not limited thereto, and the back surface electric field layer 334 and the emitter layer 332 may be formed first.

Referring to FIG. 6 , in some other examples, before the subsequent step 408 can be performed, that is, before the second passivation layer 316 is formed, the embodiment can further utilize the doping process of the back surface 328 to form multiple select The back surface field layer 342 is on the back side 328 of the substrate 312. The selective back surface electric field layer 342 and the first electrode 322 and the bus electrode 340 of the subsequently formed back surface electrode 320 are respectively located on opposite sides of the back surface electric field layer 334, and the selective back surface electric field layers respectively correspond to the first electrode 332 and the confluence Electrode 340.

After the emitter layer 332 and the back surface field layer 334 are completed, step 406 can be performed to form a first passivation layer 314 over the front side 326 of the substrate 312 and contact the emitter layer 332 using, for example, a deposition technique to passivate the front side 326. The material of the first passivation layer 314 may be tantalum oxide, tantalum nitride or aluminum oxide, and the first passivation layer 314 may be a single layer structure or a multilayer stack structure.

Next, step 408 can be performed to form a second passivation layer 316 overlying the back side 328 of the substrate 312 and contact the back surface field layer 334 using, for example, a deposition technique, thereby passivating the back side 328. The material of the second passivation layer 316 may be tantalum oxide, tantalum nitride or aluminum oxide, and the second passivation layer 316 may be a single layer structure or a multilayer stack structure. The exemplary embodiment of FIG. 7 is described in the order of forming the first passivation layer 314 and then forming the second passivation layer 316. However, the present invention is not limited thereto, and the second passivation layer 316 may be formed first to form the first passivation. Layer 314, or both first passivation layer 314 and second passivation layer 316 are formed.

In some examples, after the deposition of the second passivation layer 316 is completed in step 408, the second passivation layer 316 may be subjected to, for example, a laser opening process, thereby forming a plurality of locations in the preset position of the second passivation layer 316. A portion of the back surface electric field layer 334 formed on the back surface 328 of the substrate 312 is exposed through the opening 336 of the second passivation layer 316. The openings 336 in the second passivation layer 316 can be of various types and arrangements. The patterns and arrangements of the openings 336 are as described in the above embodiments, for example, as shown in FIGS. 5A to 5C. Let me repeat. As described in the above embodiments, the second passivation layer 316 may further have a plurality of openings 338, wherein the openings 338 may also be fabricated using laser aperture techniques or may be fabricated using photolithographic etching techniques.

In such an example, step 410 can then be performed to form the back electrode 320 on the second passivation layer 316 and fill the opening 336. In some exemplary examples, when the back surface electrode 320 is formed, the plurality of first electrodes 322 forming the back surface electrode 320 may be filled into the openings in the second passivation layer 316 by, for example, deposition or printing, such as screen printing. In 336, the second electrode 324 forming the back electrode 320 covers the second passivation layer 316 and completely covers or partially covers each of the first electrodes 322 by, for example, deposition or printing, such as screen printing. Therefore, the first electrode 322 can be in contact with the back surface electric field layer 334 exposed by the opening 336, and the second electrode 324 can be in contact with each of the first electrodes 322 to collect the current from the first electrode 322. When the first electrode 322 and the second electrode 324 are formed by screen printing, the first electrode 322 and the second electrode 324 may be further sintered. In some examples, as shown in FIG. 4, the second electrode 324 completely covers the first electrodes 322. In addition, the second electrode 324 does not completely cover the bus electrode 340, but only covers the periphery of the bus electrode 340, so that the bus electrode 340 is connected to a conductive strip (not shown).

In some exemplary examples, the materials of the first electrode 322 and the second electrode 324 are different. For example, the material of the first electrode 322 comprises a group consisting of silver and copper, and the material of the second electrode 324 comprises a group consisting of aluminum and copper. In the example where the material of the first electrode 322 contains silver and the material of the second electrode 324 contains aluminum, since the silver has a high conductivity, the electricity can be increased. The conduction efficiency of the flow can increase the efficiency of the single-sided light-receiving solar cell 302; while aluminum can collect current and reflected light and is cheaper than silver, so that the solar cell can have a high fill factor and a high short-circuit current at a lower cost. .

Next, step 412 can be performed to form the front surface electrode 318 on the first passivation layer 314 over the front side 326 of the substrate 312 by, for example, deposition or printing, such as screen printing, to substantially complete the single-sided light-receiving solar cell 302. Production. The front electrode 318 can pass through the first passivation layer 314 to contact the emitter layer 332 of the front side 326 to form an electrical connection. The material of the front electrode 318 may include silver, aluminum, or silver aluminum alloy. The exemplary embodiment of FIG. 7 is described in the order in which the back surface electrode 320 is formed first and the front surface electrode 318 is formed. However, the present invention is not limited thereto, and the front surface electrode 318 may be formed first and the back surface electrode 320 may be formed.

However, in this embodiment, the opening 336 can be formed without using the laser perforation technique, and the first electrode 322 of the opening 336 and the back electrode 320 can be simultaneously formed, and the opening 336 and the first electrode can be simultaneously formed in step 410. 322. In some examples, the composition of the first electrode 322 is different from the composition of the second electrode 324. Further, the first electrode 322 has a composition that can burn through the second passivation layer 316 at the time of sintering with respect to the second electrode 324. In some exemplary examples, when the first electrode 322 and the second electrode 324 are formed, a plurality of first electrode pastes and a plurality of bus electrode pastes may be provided on the second passivation layer 316 by, for example, screen printing. The first electrode paste and the surface of each of the bus electrode pastes are different from each other, and the first electrode paste and the bus electrode paste have a component capable of burning through the second passivation layer 316. Next, the second electrode paste may be provided to the second passivation layer 316 by, for example, screen printing. The material of the second electrode slurry is different from the material of the first electrode slurry and the bus electrode slurry, and the second electrode slurry does not have a component capable of burning through the second passivation layer 316 or is compared with the first electrode. The slurry has a component capable of burning through the second passivation layer 316, and the second electrode paste covers the first electrode slurry, and the second electrode paste is connected to the periphery of each of the bus electrode pastes. The two electrode paste corresponds to a range around the back surface 328. Then, the first electrode slurry, the second electrode slurry and the bus electrode slurry are respectively formed into a first electrode 322, a second electrode 324 and a bus electrode 340 by using a sintering process, wherein the first electrode paste and the bus electrode paste The second passivation layer 316 is burned through to form openings 336 and 338, respectively, and contacts the back surface 328. The second electrode paste and the back surface 328 are separated by the second passivation layer 316 without contacting the back surface 328.

Since the first electrode paste forming the first electrode 322 has a composition capable of burning through the second passivation layer 316, the second electrode paste forming the second electrode 324 does not have a component capable of burning through the second passivation layer 316 or The first electrode paste has a component that can burn through the second passivation layer 316 less. Therefore, during the sintering process, the first electrode 322 is disposed in the second passivation layer 316, and the second electrode 324 does not burn. A second passivation layer 316 is worn. Since the sintering method is much less damage to the back surface 328 of the substrate 312 than the conventional laser perforation method, the open circuit voltage of the single-sided light-receiving solar cell 302 can be improved. Moreover, opening the hole in the second passivation layer 316 in a sintered manner can reduce the process cost and increase the productivity.

According to the above embodiments, an advantage of the present invention is that the back electrode of the single-sided light-receiving solar cell of the present invention comprises a first electrode passing through the passivation layer, and covering the passivation layer and at least a portion of the first electricity. The second electrode on the pole. The first electrode may be made of a material having a lower resistivity than the second electrode, so that the current conduction of the first electrode can be effectively improved, so that the solar cell has high efficiency. In addition, current collection and light reflection of the second electrode can result in a solar cell having a high fill factor and a high short circuit current.

According to the above embodiments, another advantage of the present invention is that the first electrode of the back electrode of the single-sided light-receiving solar cell of the present invention has a composition that can burn through the passivation layer during sintering with respect to the second electrode, so that The electrode can be passed through the passivation layer by means of sintering. Compared with the conventional laser perforation method, the sintering method can reduce the damage to the back surface of the substrate, and can increase the open circuit voltage of the solar cell. In addition, the use of sintering methods can reduce process costs and increase production capacity.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

302‧‧‧Single-sided solar cells

312‧‧‧Substrate

314‧‧‧First passivation layer

316‧‧‧second passivation layer

318‧‧‧Front electrode

320‧‧‧Back electrode

322‧‧‧First electrode

324‧‧‧second electrode

326‧‧‧ positive

328‧‧‧Back

330‧‧‧Rough structure

332‧‧ ‧ emitter layer

334‧‧‧Back surface layer

336‧‧‧ openings

338‧‧‧Opening

340‧‧‧Concurrent electrode

Claims (11)

A single-sided light-receiving solar cell comprising: a substrate having a front surface and a back surface, wherein the substrate comprises an emitter layer disposed on the front surface, and a back surface electric field layer disposed on the back surface; a first passivation layer and a a second passivation layer covering the front surface and the back surface, wherein the second passivation layer has a plurality of openings exposing portions of the back surface electric field layer; a front electrode on the front surface; and a back surface electrode on the back surface The back electrode includes a plurality of first electrodes, a second electrode, and a plurality of bus electrodes, wherein the plurality of first electrodes are respectively disposed in the plurality of openings and contact the back surface, and the second electrode is covered by the second electrode The second passivation layer covers the range around the back surface, and the second electrode covers the plurality of first electrodes. The plurality of first electrodes are different from the material of the second electrode, and the plurality of bus electrodes are arranged in the same manner. The back surface is in contact with the second electrode. The single-sided light-receiving solar cell of claim 1, wherein the plurality of first electrodes have a component that can burn through the second passivation layer during sintering with respect to the second electrode. The single-sided light-receiving solar cell of claim 1, wherein the material of the plurality of first electrodes comprises a group consisting of silver and copper, and the material of the second electrode comprises a group consisting of aluminum and copper. The single-sided light-receiving solar cell of claim 1, wherein the plurality of openings are in a dot shape, a dotted line shape or a linear shape. The single-sided light-receiving solar cell of claim 1, wherein each of the first electrodes is completely covered or partially covered by the second electrode. A solar cell module comprising: an upper plate; a lower plate; a single-sided light-receiving solar cell according to any one of claims 1 to 5, disposed between the upper plate and the lower plate; and at least one A layer of encapsulating material is disposed between the upper plate and the lower plate, and the single-sided light-receiving solar cell is combined with the upper plate and the lower plate. A method for manufacturing a single-sided light-receiving solar cell, comprising: providing a substrate having a front surface and a back surface; forming an emitter layer and a back surface electric field layer respectively on the front surface and the back surface; forming a first passivation layer And a second passivation layer respectively covering the front surface and the back surface; and forming a front surface electrode and a back surface electrode respectively on the front surface and the back surface, the back surface electrode comprising a plurality of first electrodes, a second electrode, and a plurality of confluences The electrode, wherein the plurality of first electrodes, the second electrode, and the plurality of bus electrodes are disposed to: provide a plurality of first electrode pastes and a plurality of bus electrode pastes on the second passivation layer, wherein each of the electrodes The area of the first electrode paste and each of the bus electrode pastes are different from each other; Providing a second electrode paste on the second passivation layer, the material of the plurality of first electrode pastes is different from the material of the second electrode paste and the plurality of bus electrode pastes, and the second electrode paste Covering the plurality of first electrode pastes, the second electrode paste is connected around each of the bus electrode pastes, the second electrode paste correspondingly covers a range around the back surface; and utilizing a sintering process, Forming the plurality of first electrode pastes, the second electrode paste, and the plurality of bus electrode pastes to form the plurality of first electrodes, the second electrodes, and the plurality of bus electrodes, wherein the plurality of first electrodes The electrode paste and the plurality of bus electrode pastes are burned through the second passivation layer to form the plurality of openings to contact the back surface, and the second electrode paste and the back surface are separated by the second passivation layer. No contact with the back. The method for manufacturing a single-sided light-receiving solar cell according to claim 7, wherein the plurality of first electrode pastes have a component capable of burning through the second passivation layer, and the second electrode paste has no or Less able to burn through the components of the second passivation layer. The method for manufacturing a single-sided light-receiving solar cell according to claim 7, wherein the material of the plurality of first electrodes comprises a group consisting of silver and copper, and the material of the second electrode comprises aluminum and copper. Group. The method of manufacturing a single-sided light-receiving solar cell according to claim 7, wherein each of the first electrodes is completely covered or partially covered by the second electrode. The method for manufacturing a single-sided light-receiving solar cell according to claim 7, wherein the plurality of openings are in a dot shape, a dotted line shape or a linear shape.