Solar cell, solar battery and method for making the same

Solar cell, solar cell group and preparation method thereof

SOLAR CELL, SOLAR BATTERY AND METHOD FOR MAKING THE SAME

The invention relates to a solar cell, a solar cell group and a preparation method thereof.

Solar cells are made using the photovoltaic principle of semiconductor materials. According to the different types of semiconductor photoelectric conversion materials, solar cells can be divided into silicon-based solar cells (see the production of solar cells and polysilicon, Journal of Materials and Metallurgy, Zhang Mingjie, etc., vol6, p33-38 (2007)), gallium arsenide solar cells , Organic thin film solar cells, etc.

Currently, solar cells are mainly silicon-based solar cells. Please refer to FIG. 1, the silicon-based solar cell 10 in the prior art includes a back electrode 12, a P-type silicon layer 14, an N-type silicon layer 16 and an upper electrode 18. The P-type silicon layer 14 is made of polycrystalline silicon or monocrystalline silicon, and has a first surface 142 and a second surface 144 opposite to the first surface 142. The second surface 144 is a planar structure. The back electrode 12 is disposed on the first surface 142 of the P-type silicon layer 14 and is in ohmic contact with the first surface 142 of the P-type silicon layer 14. The N-type silicon layer 16 is formed on the second surface 144 of the P-type silicon layer 14 as a photoelectric conversion material. The surface of the N-type silicon layer 16 is a flat plane structure. The upper electrode 18 is disposed on the surface of the N-type silicon layer 16. The P-type silicon layer 14 and the N-type silicon layer 16 in the solar cell 10 form a PN junction area. When the solar cell 10 is working, light directly enters the upper electrode 18 from the side of the upper electrode 18, and passes through the The upper electrode 18 and the N-type silicon layer 16 reach the PN junction region, and the PN junction region generates a complex number of electron-hole pairs (carriers) under the excitation of photons, and the electron-hole pairs are exposed to electrostatic potential. Under the action, they are separated and moved to the back electrode 12 and the upper electrode 18 respectively. If a load is connected to both ends of the back electrode 12 and the upper electrode 18 of the solar cell 10, current will flow through the load in the external circuit.

However, in the above structure, the photons need to pass through the upper electrode 18 and the N-type silicon layer 16 before reaching the PN junction region, so that a part of the incident light is absorbed by the upper electrode 18 and the N-type silicon layer 16. Absorption makes the light absorption rate of the PN junction region lower, thereby reducing the amount of carriers excited by the PN junction region, and reducing the photoelectric conversion efficiency of the solar cell 10.

Therefore, it is necessary to provide a solar cell, a solar cell assembly and a preparation method thereof with higher photoelectric conversion efficiency.

A solar cell includes: a first electrode layer, a P-type silicon layer, an N-type silicon layer, and a second electrode layer arranged side by side and in contact with each other. The P-type silicon layer is in contact with the N-type silicon layer. A PN junction region is formed, wherein the above-mentioned layers are continuously arranged in a row along a straight line to form an integral structure. The integral structure has a first surface parallel to the straight line and a second surface opposite to the first surface. One surface is the light-receiving end surface of the solar cell that directly receives the incident light. The solar cell further includes a reflective element, and the reflective element is arranged on the side of the second surface.

A solar battery pack includes a plurality of solar cells arranged in series, each solar cell includes a first electrode layer, a P-type silicon layer, an N-type silicon layer, and a second electrode layer arranged side by side and in contact in sequence, The P-type silicon layer is in contact with the N-type silicon layer and forms a PN junction region, wherein each layer in each of the above-mentioned solar cells is along a straight line Continuously arranged in a row to form an integral structure. The integral structure has a first surface parallel to the straight line and a second surface opposite to the first surface, and the first surface is the solar cell directly receiving light. On the end surface, the solar cell further includes a reflective element, and the reflective element is arranged on the side of the second surface.

A method for preparing a solar battery pack includes the following steps: providing a plurality of battery preforms, each battery preform comprising: a first electrode layer substrate, a P-type silicon layer substrate, and a N -Type silicon layer base material and a second electrode layer base material; the above-mentioned plurality of battery preforms are stacked in one direction, so that the first electrode layer base material in each battery preform and the first electrode layer base material in adjacent battery preforms The two electrode layer substrates are in contact; the plurality of battery preforms are cut along the stacking direction to form a plurality of battery cells, each battery cell having a first cross section parallel to the stacking direction and a first cross section opposite to the first cross section Two cross-sections; a reflective element is provided in the first cross-section of each battery cell.

Compared with the prior art, when the solar cell is working, light can directly enter the light-receiving end surface. Since the light-receiving end surface is not covered by the electrode, the photon does not need to pass through the electrode and the N-type silicon layer before reaching the PN junction area. This reduces the absorption of light by the electrode and the N-type silicon layer, and improves the light absorption rate of the PN junction area. Accordingly, the PN junction area can excite more electron-hole pairs, which improves the photoelectricity of the entire solar cell. Conversion efficiency. In addition, a reflective element is provided on the second surface, and the reflective element can effectively reflect the light reaching the second surface, so that the reflected photons can be directly absorbed by the PN junction region, which further improves the entire solar cell The photoelectric conversion efficiency.

<p>20, 30, 40Solar cell</p><p>21, 31, 41Reflective element</p><p>201,301Reflective layer</p><p>22, 32, 42First electrode layer</p><p>23, 33, 43Second surface</p><p>24, 34, 44P-type silicon layer</p><p>242, 342, 443First side</p><p>244,344,444Second side</p><p>35Transparent insulating layer</p><p>26, 36, 46N-type silicon layer</p><p>262, 362, 462 third side</p><p>264,364,464The fourth side</p><p>27, 37, 47First surface</p><p>28, 38, 48Second electrode layer</p><p>29,39,49Anti-reflection layer</p><p>210Battery prefab</p><p>220First electrode layer substrate</p><p>230First Section</p><p>240P-type silicon layer substrate</p><p>241Fifth side</p><p>243Sixth side</p><p>260N-type silicon layer substrate</p><p>261Seventh side</p><p>263The eighth side</p><p>270Second Section</p><p>280Second electrode layer substrate</p><p>100Battery unit</p><p>200, 300, 400Solar battery pack</p>

Fig. 1 is a schematic diagram of the structure of a solar cell in the prior art.

Fig. 2 is a cross-sectional view of the solar cell provided by the first embodiment of the present invention.

Fig. 3 is a schematic diagram of the assembly of solar cells provided by the first embodiment of the present invention.

Fig. 4 is a cross-sectional view of the solar battery pack provided by the first embodiment of the present invention.

Fig. 5 is a cross-sectional view of a solar cell provided by a second embodiment of the present invention.

Fig. 6 is a cross-sectional view of a solar battery pack provided by a second embodiment of the present invention.

Fig. 7 is a cross-sectional view of a solar cell provided by a third embodiment of the present invention.

Fig. 8 is a cross-sectional view of a solar cell assembly provided by a third embodiment of the present invention.

Fig. 9 is a flow chart of a method for manufacturing a solar cell group provided by the second embodiment of the present invention.

Fig. 10 is a flow chart of the manufacturing process of the solar cell group provided by the second embodiment of the present invention.

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the same elements in the following embodiments are labeled with the same reference numerals.

2 and 3, the first embodiment of the present invention provides a solar cell 20, including: a first electrode layer 22, a P-type silicon layer 24, an N-type silicon layer 26 and a The second electrode layer 28. The above-mentioned layers are arranged in a row along a straight line to form an integral structure. The integral structure has a first surface 27 parallel to the straight line and a second surface 23 opposite to the first surface 27, and the first surface 27 is the The light-receiving end face of the solar cell that directly receives the incident light. Specifically, the P-type silicon layer 24 has a first side surface 242 and a second side surface 244 opposite to each other, and the N-type silicon layer 26 has a third side surface 262 and a fourth side surface 264 opposite to each other. The first electrode layer 22 is disposed on The first side surface 242 of the P-type silicon layer 24 is in electrical contact with the P-type silicon layer 24, and the second electrode layer 28 is disposed on the fourth side surface 264 of the N-type silicon layer 26 and is in contact with the N-type silicon layer. 26 electrical contacts. The second side surface 244 of the P-type silicon layer 24 is in contact with the third side surface 262 of the N-type silicon layer 26 and forms a PN junction region. The solar cell 20 also includes a reflective element 21. The reflective element 21 is arranged in contact with the second surface 23 and is electrically insulated from the first electrode layer 22 and the second electrode layer 28.

The P-type silicon layer 24 has a third surface (not shown) connected to the first side surface 242 and the second side surface 244, and the N-type silicon layer 26 has a connection with the third side surface 262 and the fourth side surface. 264 connected to the fourth surface (not marked in the figure), the third surface and the fourth surface together constitute the light-receiving end surface. Since the PN junction region is formed near the contact surface of the P-type silicon layer 24 and the N-type silicon layer 26, the PN junction region simultaneously exposes the P-type silicon layer 24 and the N-type silicon layer through the light-receiving end surface. Layer 26. Since the light-receiving end surface is not covered by the electrode layer and the silicon layer, light can be directly incident on the light-receiving end surface, so that photons reach the PN junction area.

The P-type silicon layer 24 has a layered structure, and the material of the P-type silicon layer 24 can be monocrystalline silicon, polycrystalline silicon or other P-type semiconductor materials. The thickness of the P-type silicon layer 24 along the direction from the first side surface 242 to the second side surface 244 is 200 micrometers to 300 micrometers. The included angle between the third surface and the first side surface 242 and the second side surface 244 may be greater than 0 degrees and less than 180 degrees, preferably, the included angle is 90 degrees. In this embodiment, the third surface is perpendicular to the first side surface 242 and the second side surface 244, and the P-type silicon layer 24 is a P-type single crystal silicon wafer with a thickness of 200 microns.

The N-type silicon layer 26 is formed on the second side surface 244 of the P-type silicon layer 24, and the N-type silicon layer 26 has a layered structure. The N-type silicon layer 26 can be prepared by injecting an excessive amount of N-type doping material such as phosphorus or arsenic into a silicon wafer. The N-type silicon layer 26 is along the third side surface The thickness in the direction from 262 to the fourth side 264 is 10 nanometers to 1 micron. The included angle between the fourth surface and the third side surface 262 and the fourth side surface 264 may be greater than 0 degrees and less than 180 degrees, preferably, the included angle is 90 degrees. In this embodiment, the fourth surface is perpendicular to the third side surface 262 and the fourth side surface 264, and the thickness of the N-type silicon layer 26 is 50 nm.

The PN junction region is formed near the second side surface 244 of the P-type silicon layer 24 and the third side surface 262 of the N-type silicon layer 26 that are in contact with each other. In the PN junction region, the excess electrons in the N-type silicon layer 26 tend to the P-type silicon layer 24 and form an internal electric field directed from the N-type silicon layer 26 to the P-type silicon layer 24. When the PN junction region generates complex electron-hole pairs under the excitation of light, the complex electron-hole pairs are separated under the action of the internal electric field, and the electrons in the N-type silicon layer 26 are directed toward the second electrode layer. 28 moves, the holes in the P-type silicon layer move to the first electrode layer 22, and then are collected by the first electrode layer 22 and the second electrode layer 28 to form a current, so as to realize the solar cell 20 Conversion of light energy to electrical energy.

Since the incident light does not need to pass through the first electrode layer 22 to reach the PN junction area, the first electrode layer 22 can be a continuous planar structure covering the entire surface of the first side surface 242 of the P-type silicon layer 24 Of course, the first electrode layer 22 can also be a grid-like or grid-like structure covering part of the surface of the first side surface 242. The material of the first electrode layer 22 is a conductive material, and the material may specifically be a metal, a conductive polymer, an indium tin oxide, and a carbon nanotube structure. Preferably, the first electrode layer 22 is composed of a continuous metal material layer with a planar structure, and the metal material layer covers the entire first side surface 242. The metal material can be aluminum, copper, or silver. The thickness of the first electrode layer 22 is not limited, and is preferably 50 nanometers to 300 nanometers. In this embodiment, the first electrode layer 22 is an aluminum foil with a thickness of about 200 nanometers.

Since the incident light does not need to pass through the second electrode layer 28 to reach the PN junction area, the second electrode layer 28 can be a continuous planar structure covering the fourth side of the N-type silicon layer 26 The entire surface of the surface 264 may also be a grid-like or grid-like structure covering part of the surface of the fourth side surface 264. The material of the second electrode layer 28 is a conductive material, and the material can be specifically selected from metals, conductive polymers, indium tin oxide, or carbon nanotubes. Preferably, the second electrode layer 28 is composed of a continuous metal material layer with a planar structure, and the metal material layer covers the entire fourth side surface 264. The metal material can be aluminum, copper, silver, or the like. The thickness of the second electrode layer 28 is not limited, and is preferably 50 nanometers to 300 nanometers. In this embodiment, the second electrode layer 28 is an aluminum foil with a thickness of about 200 nanometers.

Both the first electrode layer 22 and the second electrode layer 28 may be opaque, so that light can be prevented from passing through the first electrode layer 22 and the second electrode layer 28, which may reduce the photoelectric conversion efficiency.

The reflective element 21 includes a reflective layer 201. As shown in FIGS. 2 and 3, the reflective layer 201 and the second surface 23 are arranged in contact with each other and are electrically insulated from the first electrode layer 22 and the second electrode layer 28. The reflective layer 201 is composed of a continuous metal material layer with a planar structure. The metal material can be one of aluminum, gold, copper, and silver or an alloy of any combination of the foregoing. The thickness of the reflective layer 201 is 10 nanometers to 100 micrometers, preferably 50 nanometers. In this embodiment, the reflective layer 201 is an aluminum foil with a thickness of 50 nm.

The reflective layer 201 can be formed on the second surface 23 by methods such as vacuum evaporation or magnetron sputtering, and it must be ensured that neither the first electrode layer 22 nor the second electrode layer 28 is covered by the reflective layer 201. Masking or etching can be used to make the first electrode layer 22 and the second electrode layer 28 exposed outside the reflective layer 201.

When the solar cell 20 is working, it is different from the traditional way of irradiating the fourth side surface 264 covered with the meshed metal electrode or the transparent electrode, but in order to use the third surface and the fourth surface as the light-receiving end surface to receive the incident light. . Since the light-receiving end face is not second The electrode layer 28 is covered, that is, the PN junction area directly exposes the P-type silicon layer 24 and the N-type silicon layer 26, so that photons can be directly absorbed by the PN junction area without passing through the second electrode layer 28 and the N-type silicon layer. It reaches the PN junction region after 26, thereby reducing the absorption of light by the second electrode layer 28 and the N-type silicon layer 26, and increasing the absorption rate of light in the PN junction region. Accordingly, the PN junction region can excite more Electron-hole pair. Moreover, since the second electrode layer 28 is not provided on the light-receiving end surface, there is no need to consider the influence factors of the second electrode layer 28 blocking light, so that the second electrode layer 28 can be provided in any shape, even one side. The shape structure covers the entire fourth side surface of the N-type silicon layer 26, thereby increasing the area of the entire second electrode layer 28 and reducing the diffusion of carriers generated in the PN junction region to the second electrode layer The length of 28 reduces the internal loss of carriers, thereby improving the photoelectric conversion efficiency of the entire solar cell 20. In addition, the reflective element 21 can effectively reflect the light reaching the second surface 23, so that the reflected photons can be directly absorbed by the PN junction region, which further improves the light absorption rate of the PN junction region. Ground, so that the PN junction region can excite more electron-hole pairs, thereby further improving the photoelectric conversion efficiency of the entire solar cell 20.

In addition, the included angle between the light-receiving end surface and the fourth side surface 264 may be greater than 0 degrees and less than 180 degrees, preferably the included angle is 90 degrees.

Further, in order to reduce the reflection of light and make more light energy be absorbed by the PN junction area, an anti-reflection layer 29 can be further provided on the light-receiving end surface. The anti-reflection layer 29 can make light incident and reduce light Reflection, and less absorption of light, the material of the anti-reflection layer 29 is silicon nitride (Si₃N₄) Or silicon dioxide (SiO₂)Wait. The thickness of the anti-reflective layer 29 may be less than 150 nm. In this embodiment, the anti-reflective layer is a 900 angstrom (Å) silicon nitride layer.

The thickness of the entire solar cell 20 is from the first surface 27 to the second surface 23 the distance. When the light-receiving end surface is perpendicular to the fourth side surface 264, the thickness of the solar cell 20 is also such that the P-type silicon layer 24, the N-type silicon layer 26, the first electrode layer 22, and the second electrode layer 28 are perpendicular to them. The width in the direction of the light-receiving end surface. The thickness of the solar cell 20 is not limited, and can be set according to the transmittance of the P-type silicon layer 24 and the N-type silicon layer 26 of the light incident from the light-receiving end surface. Preferably, the thickness is a thickness when the light transmittance is zero, so that the entire solar cell 20 can effectively use the absorbed light. In this embodiment, the thickness of the solar cell 20 is 50 micrometers to 300 micrometers.

In addition, since there is no need to consider the light blocking factors of the first electrode layer 22 and the second electrode layer 28, the shape and structure requirements of the first electrode layer 22 and the second electrode layer 28 are reduced, thereby making the preparation method simple.

Please refer to FIG. 4, the solar cells 20 provided by the first embodiment of the present invention can be arranged in series to form a solar cell group 200. Preferably, the plurality of solar cells 20 are arranged side by side and in contact. Specifically, the second electrode layer 28 of each solar cell 20 and the first electrode layer 22 of the adjacent solar cell 20 can be bonded or bonded to each other through a conductive adhesive, and the materials of the two can be the same or different. When the two materials are the same, the second electrode layer 28 of each solar cell 20 and the first electrode layer 22 of the adjacent solar cell 20 can be bonded into one body. The plurality of solar cells 20 can be pressed together by a pressing machine.

The number of solar cells 20 included in the solar cell group 200 is not limited, and can be set according to the actual required output voltage. In this embodiment, the solar cell group 200 includes 100 solar cells 20. The working voltage of the solar cell group 200 is an integer multiple of the working voltage of a single solar cell 20.

In addition, in order to reduce the occupancy of the light-receiving area of the entire solar cell group 200 by the electrodes, the first electrode layer 22 and the second electrode layer between the two adjacent solar cells 20 The total thickness of 28 is preferably 100 nm to 400 nm. In this embodiment, the total thickness of the first electrode layer 22 and the second electrode layer 28 along the direction from the first side surface 242 to the second side surface 244 is 300 nm.

5, a second embodiment of the present invention provides a solar cell 30, including: a first electrode layer 32, a P-type silicon layer 34, an N-type silicon layer 36, and a second electrode arranged side by side and in contact with each other in sequence Layer 38. The above-mentioned layers are continuously arranged in a row along a straight line to form an integral structure. The integral structure has a first surface 37 parallel to the straight line and a second surface 33 opposite to the first surface 37, and the first surface 37 is the The light-receiving end face of the solar cell that directly receives the incident light. Specifically, the P-type silicon layer 34 has a first side surface 342 and a second side surface 344 opposite to each other, and the N-type silicon layer 36 has a third side surface 362 and a fourth side surface 364 opposite to each other. The first electrode layer 32 is disposed on the first side surface 342 of the P-type silicon layer 34 and is in electrical contact with the P-type silicon layer 34, and the second electrode layer 38 is disposed on the fourth side surface 364 of the N-type silicon layer 36 , And make electrical contact with the N-type silicon layer 36. The second side surface 344 of the P-type silicon layer 34 is in contact with the third side surface 362 of the N-type silicon layer 36 and forms a PN junction region. The solar cell 30 also includes a reflective element 31. The solar cell 30 provided in this embodiment is basically the same as the solar cell 20 provided in the first embodiment, except that the reflective element 31 and the second surface 33 are spaced apart.

The reflective element 31 includes a reflective layer 301, and the reflective layer 301 is spaced apart from the second surface 33. The reflective element 31 also includes a transparent insulating layer 35. The transparent insulating layer 35 covers the entire second surface 33, and the reflective layer 301 covers the entire transparent insulating layer 35, so that the reflective layer 301 and the second surface 33 are insulated from each other. The transparent insulating layer 35 includes a plurality of nano particles. The material of the transparent insulating layer 35 is a material with certain chemical stability, such as diamond-like carbon, silicon, silicon carbide , Silicon dioxide, boron nitride, aluminum oxide and silicon nitride, etc. or one or more of them. The thickness of the transparent insulating layer 35 is 10 nanometers to 100 micrometers. In order to reduce the absorption of light by the transparent insulating layer 35, the thickness of the transparent insulating layer 35 is preferably 10 nanometers to 50 nanometers. The transparent insulating layer 35 can be directly grown or coated on the second surface 33 by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Then, the reflective layer 301 is formed on the transparent insulating layer 35 by a method such as vacuum evaporation or magnetron sputtering.

It can be understood that an insulating layer may not be provided between the reflective layer 301 and the second surface 33, that is, the reflective layer 301 and the second surface 33 are arranged at a certain distance and insulated from each other. The distance is not limited, and is preferably 1 mm to 5 cm. The reflective element 31 also includes a substrate (not shown). The reflective layer 301 is disposed on the surface of the substrate. The shape of the substrate is not limited. Preferably, the substrate is a plate-shaped body, and the shape of the substrate is consistent with the shape of the second surface 33. The material of the substrate is insulating materials such as glass, ceramics, and silicon dioxide. In this embodiment, the substrate is preferably a ceramic plate. The reflective layer 301 can be formed on the surface of the substrate by methods such as vacuum evaporation or magnetron sputtering.

Please refer to FIG. 6, the solar cells 30 provided in the second embodiment of the present invention can be arranged in series to form a solar cell group 300. Preferably, the plurality of solar cells 30 are arranged side by side and in contact. The solar cell assembly 300 provided in this embodiment is basically the same as the solar cell assembly 200 provided in the first embodiment, except that the reflective element 31 of the solar cell 30 is spaced apart from the second surface 33.

The reflective element 31 includes a reflective layer 301, and the reflective layer 301 is spaced apart from the second surface 33. The plurality of solar cells 30 share the reflective element 31. Furthermore, the reflective element 31 further includes a transparent insulating layer 35. The transparent insulating layer 35 covers the entire second surface 33, and the reflective layer 301 covers the entire transparent insulating layer 35, so that the reflective layer 301 and the second surface 33 are insulated from each other.

It can be understood that an insulating layer may not be provided between the reflective layer 301 and the second surface 33, that is, the reflective element 31 and the second surface 33 may also be arranged at a certain distance and insulated from each other. The distance is not limited, and is preferably 1 mm to 5 cm. The reflective element 31 further includes a substrate (not shown), and the reflective layer 301 is disposed on the surface of the substrate.

The number of solar cells 30 included in the solar cell group 300 is not limited, and can be set according to the actual required output voltage. In this embodiment, the solar cell group 300 includes 100 solar cells 30. The working voltage of the solar cell group 300 is an integer multiple of the working voltage of one solar cell 30.

In addition, in order to reduce the occupancy of the light-receiving area of the entire solar cell group 300 by the electrodes, the total thickness of the first electrode layer 32 and the second electrode layer 38 between the two adjacent solar cells 30 is preferably 100 nm~ 400 nm. In this embodiment, the total thickness of the first electrode layer 32 and the second electrode layer 38 along the direction from the first side surface 342 to the second side surface 344 is 300 nm.

Referring to FIG. 7, a third embodiment of the present invention provides a solar cell 40, including: a first electrode layer 42, a P-type silicon layer 44, an N-type silicon layer 46, and a second electrode arranged side by side and in contact in sequence Layer 48. The above-mentioned layers are arranged in a row along a straight line to form an integral structure. The integral structure has a first surface 47 parallel to the straight line and a second surface 43 opposite to the first surface 47, and the first surface 47 is the The light-receiving end face of the solar cell that directly receives the incident light. Specifically, the P-type silicon layer 44 has a first side surface 442 and a second side surface 444 opposite to each other, and the N-type silicon layer 46 has a third side surface 462 and a fourth side surface 464 opposite to each other. The first electrode layer 42 is disposed on the P The first side surface 442 of the N-type silicon layer 44 is in electrical contact with the P-type silicon layer 44. The second electrode layer 48 is disposed on the fourth side surface 464 of the N-type silicon layer 46 and is electrically connected to the N-type silicon layer 46. get in touch with. The second side surface 444 of the P-type silicon layer 44 is in contact with the third side surface 462 of the N-type silicon layer 46 and forms a PN junction region. The solar cell 20 also includes a reflective element 41. The solar cell 40 provided in this embodiment is basically the same as the solar cell 20 provided in the first embodiment, except that the reflective element 41 is a plurality of microstructures arranged on the second surface 43.

The microstructure is disposed on the second surface 43. The microstructures are grooves or protrusions. The shape of the microstructure is one or more of V-shaped, cylindrical, semi-spherical, pyramidal, and pyramidal with the tip portion cut off. The microstructures are evenly distributed on the second surface 43. Further, the reflective element 41 further includes a reflective material, and the reflective material is disposed on the surface of the microstructure. The reflective material is one of aluminum, gold, copper and silver or an alloy of any combination of the foregoing. The reflective material can be formed on the surface of the microstructure by methods such as vacuum evaporation or magnetron sputtering.

The reflecting element 41 can realize total reflection of the light beam to reflect the light beam incident on the second surface 43 so that more light can be absorbed by the PN junction area. By performing microstructure treatment on the second surface 43, the microstructure is formed on the second surface 43. The method of forming the microstructure is not limited.

Referring to FIG. 8, the solar cells 40 provided by the third embodiment of the present invention can be arranged in series to form a solar cell group 400. Preferably, the plurality of solar cells 40 are arranged side by side and in contact. The solar cell group 400 provided in this embodiment is basically the same as the solar cell group 200 provided in the first embodiment, except that the reflective elements 41 of the solar cell 40 are plurally arranged on the second surface 43. microstructure.

The microstructure is disposed on the second surface 43. The microstructures are grooves or protrusions. The shape of the microstructure is one or more of V-shaped, cylindrical, semi-spherical, pyramidal, and pyramidal with the tip portion cut off. The microstructures are evenly distributed on the second surface 43. Further, the reflective element 41 further includes a reflective material, and the reflective material is disposed on the surface of the microstructure. The reflective material is one of aluminum, gold, copper and silver or an alloy of any combination of the foregoing.

The number of solar cells 40 included in the solar cell group 400 is not limited, and can be set according to the actual required output voltage. In this embodiment, the solar cell group 400 includes 100 solar cells 40. The working voltage of the solar cell group 400 is an integer multiple of the working voltage of one solar cell 40.

Referring to FIGS. 9 and 10, the present invention further provides a method for preparing the solar battery pack 200, including the following steps: S1, providing a plurality of battery preforms 210, each of the battery preforms 210 includes: sequentially stacked and arranged in contact A first electrode layer substrate 220, a P-type silicon layer substrate 240, an N-type silicon layer substrate 260, and a second electrode layer substrate 280; S2, the plurality of battery preforms 210 are laminated in one direction Set up so that the first electrode layer substrate 220 in each battery preform 210 is in contact with the second electrode layer substrate 280 in the adjacent battery preform 210; S3, the plurality of battery preforms are cut along the lamination direction 210. A plurality of battery cells 100 are formed. Each battery cell 100 has a first cross section 230 parallel to the stacking direction and a second cross section 270 opposite to the first cross section 230; S4, at all the battery cells 100 The first cross section 230 is provided with a reflective element.

In the step S1, the P-type silicon layer substrate 240 has opposite fifth side surfaces 241 and The sixth side surface 243. The N-type silicon layer substrate 260 has a seventh side surface 261 and an eighth side surface 263 opposite to each other. The first electrode layer substrate 220 is disposed on the fifth side surface 241 of the P-type silicon layer substrate. The second electrode layer substrate 280 is disposed on the eighth side surface 263 of the N-type silicon layer substrate 260, the sixth side surface 243 of the P-type silicon layer substrate 240 and the seventh side surface 261 of the N-type silicon layer substrate 260 Contact and form a PN junction area. The P-type silicon layer substrate 240 is a P-type silicon wafer, and the material of the P-type silicon wafer can be monocrystalline silicon, polycrystalline silicon or other P-type semiconductor materials. In this embodiment, the P-type silicon layer substrate 240 is a P-type single crystal silicon wafer. The thickness of the P-type monocrystalline silicon wafer may be 200 micrometers to 300 micrometers. The area and shape of the P-type silicon layer substrate 240 are not limited, and can be selected according to actual needs. The N-type silicon layer substrate 260 can be prepared by injecting an excessive amount of N-type dopant materials such as phosphorus or arsenic into a silicon wafer substrate. The thickness of the N-type silicon layer substrate 260 is 10 nanometers to 1 micrometer.

The materials of the first electrode layer substrate 220 and the second electrode layer substrate 280 may be the same or different. Preferably, the first electrode layer substrate 220 and the second electrode layer substrate 280 are made of a metal material with a continuous planar structure. Layer formation, the metal material can be aluminum, copper, or silver. The first electrode layer substrate 220 and the second electrode layer substrate 280 can be bonded to the surfaces of the P-type silicon layer substrate 240 and the N-type silicon layer substrate 260 by a conductive adhesive, or can be vacuum evaporated, or Magnetron sputtering and other methods are formed on the surfaces of the P-type silicon layer substrate 240 and the N-type silicon layer substrate 260.

In the above step S2, the stacked battery preforms 210 may be bonded by a conductive adhesive. In addition, when the materials of the first electrode layer substrate 220 and the second electrode layer substrate 280 of the adjacent battery preforms 210 are the same, the plurality of battery preforms 210 stacked on each other can be pressed together, so that the adjacent battery The electrode layers of the preform 210 are bonded to each other. The pressing force of the pressing machine to press the plurality of battery preforms 210 stacked on each other is not limited. It is only necessary to make the adjacent first electrode layer substrate 220 and the second electrode layer substrate 280 mutual Just bond them together.

In the above step S3, the method and cutting direction of cutting the plurality of stacked battery preforms 210 are not limited, and the cutting direction is specifically capable of passing through the fifth side surface 241, the sixth side surface 243, the seventh side surface 261 and the The eighth side surface 263 forms a plurality of battery cells 100, and each battery cell 100 has a first cross section 230 parallel to the stacking direction. The cutting direction is preferably along a direction perpendicular to the plane where the first electrode layer substrate 220 and the second electrode layer substrate 280 are located. Through this cutting method, a P-type silicon layer substrate 240 and an N-type silicon layer substrate 260 that are stacked together and directly exposed to the P-type silicon layer substrate can be formed on each battery cell 100. 240 and the second cross section 270 outside the N-type silicon layer substrate 260. The second cross section 270 is opposite to the first cross section 230.

In the above step S4, a reflective element is provided on one side of the first cross section 230 of each battery cell 100. The method for setting the reflective element is to prepare a reflective layer in contact with the first cross section 230 and electrically insulated from the first electrode layer substrate 220 and the second electrode layer substrate 280. The reflective layer is formed on the first cross section 230 by a method such as vacuum evaporation or magnetron sputtering, and it is ensured that the reflective layer does not cover the first electrode layer substrate 220 and the second electrode layer substrate 280. Masking or etching may be used to expose the first electrode layer substrate 220 and the second electrode layer substrate 280 to the outside of the reflective layer.

Further, the method for setting the reflective element may also include preparing a transparent insulating layer to cover the entire first section 230, and then preparing a reflective layer to cover the transparent insulating layer. The transparent insulating layer may be directly grown or coated on the first section 230 by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Then, the reflection is formed on the transparent insulating layer by vacuum evaporation or magnetron sputtering. Floor.

Furthermore, the method of setting the reflective element may also be to form a plurality of microstructures on the first cross section 230. The microstructure is obtained by performing microstructure processing on the first section 230. The method of forming the microstructure is not limited. It can be understood that a reflective material can be provided on the surface of the microstructure, and the reflective material can be formed on the surface of the microstructure by methods such as vacuum evaporation or magnetron sputtering.

The reflective element can effectively reflect the light reaching the first cross-section 230, so that the reflected photons can be directly absorbed by the PN junction region, which further improves the light absorption rate of the PN junction region, and accordingly , So that the PN junction region can excite more electron-hole pairs, and further improve the photoelectric conversion efficiency of the entire solar cell group.

Further, after the above step S4, an anti-reflection layer is formed on the second section 270 of each battery cell 100 by vacuum evaporation or magnetron sputtering. The anti-reflection layer can allow light to enter and reduce the amount of light. Reflection, and less absorption of light, the material of the anti-reflection layer is silicon nitride (Si₃N₄) Or silicon dioxide (SiO₂)Wait. The thickness of the anti-reflection layer can be less than 150 nm. In this embodiment, the anti-reflection layer is a 900 angstrom (Å) silicon nitride layer.

In the preparation method of the solar battery pack 200, the plurality of battery cells 100 are obtained by cutting the plurality of stacked battery preforms 210. The preparation method effectively utilizes materials and achieves the effect of maximizing resource utilization. . Moreover, by arranging a reflective element on one side of the first cross section 230, the photoelectric conversion efficiency of the solar cell assembly is improved.

In summary, this publication clearly meets the requirements of a patent for invention, so it filed a patent application in accordance with the law. Please. However, the above are only preferred embodiments of the present invention, and cannot be used to limit the claims of this case. Jufan conventional equivalent modifications or changes in mental skill of the case made by the person assistance under this invention, are culvert shall cover within the requested item.