WO2023071183A1 - 一种太阳能电池及其制备方法 - Google Patents

一种太阳能电池及其制备方法 Download PDF

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WO2023071183A1
WO2023071183A1 PCT/CN2022/096065 CN2022096065W WO2023071183A1 WO 2023071183 A1 WO2023071183 A1 WO 2023071183A1 CN 2022096065 W CN2022096065 W CN 2022096065W WO 2023071183 A1 WO2023071183 A1 WO 2023071183A1
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back surface
emitter
surface field
solar cell
layer
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PCT/CN2022/096065
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English (en)
French (fr)
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邓明璋
徐文州
何宇
陈浩
周凡
孟夏杰
周鹏宇
姚骞
邢国强
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通威太阳能(眉山)有限公司
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Priority to EP22885093.9A priority Critical patent/EP4254513A4/en
Priority to AU2022377798A priority patent/AU2022377798A1/en
Priority to US18/553,369 priority patent/US20240186439A1/en
Publication of WO2023071183A1 publication Critical patent/WO2023071183A1/zh

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Definitions

  • the present application relates to the field of photovoltaic technology, in particular, to a solar cell and a preparation method thereof.
  • the front light-receiving area of a solar cell is an important factor affecting its photoelectric conversion efficiency.
  • the front of a conventional solar cell is shielded by a grid structure, which will cause a loss of current, thereby reducing the photoelectric conversion efficiency.
  • the recombination of electron-hole pairs inside the cell determines the photoelectric conversion efficiency of the solar cell.
  • the diffusion layer formed by conventional diffusion has problems such as a high recombination rate of electron-hole pairs, which has always restricted solar energy.
  • One of the important factors of battery efficiency is the important factors of battery efficiency.
  • the present application provides a solar cell and a preparation method thereof, which can increase the light-receiving area of the front surface and reduce the recombination rate of electron-hole pairs, thereby effectively improving the photoelectric conversion efficiency of the solar cell.
  • Some embodiments of the present application provide a solar cell, the backside of the substrate has alternately distributed emitter regions and back surface field regions.
  • An emitter is formed in the emitter region, and the material of the emitter is boron-doped single crystal silicon.
  • a back surface field is formed in the back surface field region; the back surface field includes a stacked tunnel oxide layer and a polysilicon layer, the polysilicon layer is made of phosphorus-doped polysilicon, and the tunnel oxide layer is located between the polysilicon layer and the polysilicon layer.
  • the positive electrode of the solar cell is electrically connected to the emitter, and the negative electrode of the solar cell is electrically connected to the back surface.
  • the emitter connected to the positive electrode is arranged on the back of the substrate, so that there is no positive electrode and corresponding grid line structure on the front of the substrate, which can increase the light-receiving area of the front and reduce the shading of the front of the substrate.
  • Current loss which can improve the photoelectric conversion efficiency of solar cells.
  • a tunnel oxide layer and a polysilicon layer made of phosphorus-doped polysilicon are set as the back surface field.
  • the tunneling effect of the tunnel oxide layer allows electrons to pass through but holes cannot pass through, and the phosphorus-doped polysilicon forms a passivation contact, thereby Can reduce the recombination rate of electron-hole pairs.
  • the emitter region and the back surface field region may be arranged side by side along the first predetermined direction.
  • each back surface field region may be 100 ⁇ m to 300 ⁇ m, and the distance between two adjacent back surface field regions may be 600 ⁇ m to 1500 ⁇ m.
  • the emitter region and the back surface field region have an appropriate size and spacing, so that the solar cell has an appropriate grid line density, which facilitates printing operations during the preparation process; while ensuring metal contact, it can also effectively realize The purpose of reducing the recombination of the emitter, increasing the open circuit voltage of the battery, and improving the photoelectric conversion efficiency of the battery.
  • the size of the positive electrode may be 50 ⁇ m to 200 ⁇ m, and the size of the negative electrode may be 40 ⁇ m to 100 ⁇ m.
  • the positive electrode can be electrically connected with the inner wall of the emitter contact hole opened on the emitter, and the negative electrode can be electrically connected with the inner wall of the back surface field contact hole opened on the back surface field; the emitter contact hole and the back surface field
  • the contact holes may each have a diameter of 25 ⁇ m to 50 ⁇ m.
  • the distance between the centers of two adjacent emitter contact holes on each emitter may be 20 ⁇ m to 80 ⁇ m, and the center distance between two adjacent back surface field contact holes on each back surface
  • the pitch may be 20 ⁇ m to 80 ⁇ m.
  • each emitter region and the back surface field region may extend along a second preset direction, and the second preset direction may be perpendicular to the first preset direction; in the second preset direction, each emitter
  • the center-to-center distance between two adjacent emitter contact holes on the upper surface may be 50 ⁇ m to 100 ⁇ m, and the center-to-center distance between two adjacent back surface field contact holes on each back surface may be 20 ⁇ m to 80 ⁇ m.
  • the emitters and the back surface fields may be arranged alternately, so that the emitter contact holes and the back surface field contact holes are arranged alternately.
  • the emitter contact holes may be arranged in at least one column, wherein a plurality of emitter contact holes in each column of emitter contact holes are distributed at intervals along the second preset direction, and multiple columns The emitter contact holes are distributed at intervals along the first preset direction; in each back surface field region, the back surface field contact holes may be arranged in at least one column, wherein a plurality of back surface field contact holes in each column of back surface field contact holes The contact holes are distributed at intervals along the second preset direction, and the rows of back surface field contact holes are distributed at intervals along the first preset direction.
  • the electrodes and contact holes have appropriate specifications and spacing, have good matching with the emitter and the back surface field, and can effectively control the metallization area of the solar cell, and at the same time facilitate the printing operation during the preparation process .
  • the tunnel oxide layer may be a silicon dioxide film, and the thickness may be 1 nm to 5 nm; optionally, the thickness of the tunnel oxide layer may be 1 nm to 3 nm.
  • the polysilicon layer may have a thickness of 100 nm to 500 nm.
  • the solar cell may further include a silicon nitride antireflection layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer.
  • the silicon nitride antireflection layer may be formed on the antireflection textured surface of the front side of the substrate.
  • An aluminum oxide passivation layer may be formed on the surface of the emitter and the back surface field.
  • a silicon nitride passivation layer may be formed on the surface of the aluminum oxide passivation layer.
  • the positive electrode is electrically connected to the emitter after penetrating the silicon nitride passivation layer and the aluminum oxide passivation layer
  • the negative electrode is electrically connected to the emitter after penetrating the silicon nitride passivation layer and the aluminum oxide passivation layer.
  • the silicon nitride antireflection layer may have a thickness of 80nm to 120nm.
  • the thickness of the aluminum oxide passivation layer may be 3nm to 20nm.
  • the thickness of the silicon nitride passivation layer may be 75nm to 150nm.
  • a front surface field may also be formed on the surface of the anti-reflection texture by shallow phosphorus diffusion, and the front surface field is located between the anti-reflection texture and the silicon nitride anti-reflection layer.
  • the solar cell has appropriate structural layers, and each structural layer has an appropriate thickness, which is beneficial to ensure the photoelectric conversion efficiency of the solar cell.
  • the solar cell may further include positive bus bars and negative bus bars distributed at intervals.
  • the positive bus bar can be electrically connected to each positive electrode, and the negative bus bar can be electrically connected to each negative electrode; there is insulating glue between the positive bus bar and the negative electrode and between the negative bus bar and the positive electrode. .
  • both the positive electrode and the negative electrode may extend along a third preset direction, the extending direction of the positive bus bar and the negative bus bar is perpendicular to the extending direction of the positive electrode, and the negative electrode The extending direction of the bus bar is perpendicular to the extending direction of the negative electrode.
  • multiple electrodes can be conveniently connected through the bus bar; the arrangement of the insulating glue can effectively avoid the short circuit of the positive and negative electrodes, and the preparation is convenient.
  • the substrate is diffused with boron, and a boron diffusion layer and borosilicate glass on the surface of the boron diffusion layer are formed on the surface of the substrate.
  • the first surface of the substrate is used as the back of the substrate, and laser slotting and boron diffusion layer etching are performed sequentially on the local area of the borosilicate glass on the back of the substrate to form the back surface field area; the ungrooved and etched area is the emission
  • the pole regions, the emitter regions and the back surface field regions are arranged alternately on the backside of the substrate.
  • a tunnel oxide layer is grown on the backside of the substrate and then an intrinsic amorphous silicon layer is deposited.
  • Phosphorus is diffused on the substrate so that the intrinsic amorphous silicon layer is formed as a polysilicon layer made of phosphorus-doped polysilicon, and phosphosilicate glass is formed on the surface of the polysilicon layer.
  • the corrosion-resistant slurry is printed on the surface of the phosphosilicate glass corresponding to the back surface field area, and the corrosion-resistant slurry is dried; the corrosion-resistant slurry is soluble in alkali and insoluble in acid.
  • the phosphorosilicate glass corresponding to the emitter area is removed with acid.
  • the corrosion-resistant paste and the polysilicon layer and tunnel oxide layer corresponding to the emitter region are removed with alkali.
  • the remaining phosphosilicate glass and borosilicate glass are removed from the backside of the substrate with acid.
  • the boron diffusion layer of the remaining material in the emitter area acts as the emitter.
  • the remaining tunnel oxide layer and polysilicon layer in the back surface field region serve as the back surface field.
  • the positive electrode is electrically connected to the emitter and the negative electrode is electrically connected to the back surface field.
  • borosilicate glass (BSG) and phosphosilicate glass (PSG) are formed by diffusion as masks, and at the same time, solar cells as provided in some of the above-mentioned embodiments can be formed by local laser groove etching and printing paste
  • the structure can increase the light-receiving area of the front and reduce the recombination rate of electron-hole pairs, thereby effectively improving the photoelectric conversion efficiency of the solar cell.
  • the step of removing the corrosion-resistant slurry and the polysilicon layer and the tunnel oxide layer corresponding to the emitter region with alkali may include:
  • the first alkaline solution is used to remove the corrosion-resistant slurry, and then the second alkaline solution is used to remove the polysilicon layer and the tunnel oxide layer corresponding to the emitter region.
  • the alkalinity of the first lye is smaller than that of the second lye.
  • the removal of the corrosion-resistant slurry is carried out in separate steps with the removal of the polysilicon layer and the tunneling oxide layer, which facilitates separate tank treatment and can effectively improve the cross-contamination of the tank.
  • Using the second lye with relatively high alkalinity is beneficial to more fully remove the polysilicon layer and the tunnel oxide layer corresponding to the emitter region.
  • the step of electrically connecting the positive electrode to the emitter and the negative electrode to the back surface field may include:
  • An emitter contact hole is opened on the emitter, and a positive electrode is printed on a region corresponding to the emitter contact hole.
  • a back surface field contact hole is opened in the back surface field, and a negative electrode is printed in a region corresponding to the surface field contact hole.
  • the electrode is formed by printing metal paste after opening holes, which is beneficial to reduce the area of metallization, thereby reducing the metal recombination on the back of the battery and improving the photoelectric conversion efficiency.
  • the second surface of the substrate is used as the front surface of the substrate, and the step of forming anti-reflection suede on the surface of the substrate may include:
  • the texturing step is carried out after the N-type region and the P-type region are prepared, which can effectively reduce the damage to the anti-reflective textured surface caused by the previous process.
  • the texturing step is carried out before the step of removing the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate, and the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate are used as a mask to effectively prevent the texturing step from affecting the N-type area. and damage to the P-type region.
  • FIG. 1 is a schematic structural diagram of a first solar cell provided in an embodiment of the present application
  • Fig. 2 is a schematic diagram of the division and slotting structure on the back of the solar cell provided by the embodiment of the present application;
  • FIG. 3 is a schematic diagram of the connection of the electrodes of the solar cell provided by the embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a second solar cell provided in an embodiment of the present application.
  • Fig. 5 is a schematic diagram of laser grooving in the method for preparing a solar cell provided by the embodiment of the present application.
  • Icon 100-solar cell; 101-substrate; 110-emitter region; 111-emitter; 120-back surface field region; 121-back surface field; 122-tunnel oxide layer; 123-polysilicon layer; 131-positive Electrode; 132-emitter contact hole; 133-positive bus bar; 141-negative electrode; 142-back surface field contact hole; 143-negative bus bar; 170-alumina passivation layer; 180-silicon nitride passivation layer; 190-front surface field; 200-spot; 300-laser grooved area; a-first preset direction; b-second preset direction; c - Third preset direction.
  • orientations or positional relationships indicated by the terms “front”, “rear”, “center”, “inner”, “outer”, etc. are based on the orientations or positional relationships shown in the drawings , or the orientation or positional relationship that the application product is usually placed in use, is only for the convenience of describing the application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation or be constructed in a specific orientation and operation, and therefore should not be construed as limiting the application.
  • an embodiment of the present application provides a solar cell 100 , the back of a substrate 101 has emitter regions 110 and back surface field regions 120 alternately distributed.
  • the direction in which the emitter regions 110 and the back surface field regions 120 are alternately distributed side by side is the first preset direction a
  • the extending direction of each emitter region 110 and the back surface field region 120 is the second preset direction a.
  • a direction b is set; the first predetermined direction a and the second predetermined direction b are perpendicular to each other, and both are parallel to the surface of the substrate 101 .
  • the thickness direction of the solar cell 100 is a third predetermined direction c, and the third predetermined direction c is perpendicular to the surface of the substrate 101 .
  • the emitter region 110 is formed with an emitter 111 , and the material of the emitter 111 is boron-doped single crystal silicon.
  • the back surface field region 120 is formed with a back surface field 121; the back surface field 121 includes a stacked tunnel oxide layer 122 and a polysilicon layer 123, the polysilicon layer 123 is made of phosphorus-doped polysilicon, and the tunnel oxide layer 122 is located between the polysilicon layer 123 and the polysilicon layer 123. between polysilicon layers 123 .
  • the positive electrode 131 of the solar cell 100 is electrically connected to the emitter 111
  • the negative electrode 141 of the solar cell 100 is electrically connected to the back surface field 121 .
  • the emitter 111 connected to the positive electrode 131 can be arranged on the back of the substrate 101, so that the front of the substrate 101 has no positive electrode 131 and the corresponding grid structure, which can increase the light receiving area of the front and reduce the
  • the current loss caused by the shading on the front side of the small substrate 101 can improve the photoelectric conversion efficiency of the solar cell.
  • a tunneling oxide layer 122 and a polysilicon layer 123 made of phosphorus-doped polysilicon are set on the back side of the substrate 101 as the back surface field 121.
  • the tunneling effect of the tunneling oxide layer 122 can allow electrons to pass through but holes cannot pass through, forming phosphorus-doped polysilicon. Passivate the contacts, thereby reducing the rate of recombination of electron-hole pairs.
  • the size of each back surface field region 120 may be 100 ⁇ m to 300 ⁇ m, such as but not limited to any of 100 ⁇ m, 150 ⁇ m, 200 ⁇ m, 250 ⁇ m and 300 ⁇ m. A range between one or any of the two enables the back surface field region 120 to have an appropriate size, and enables an appropriate distance between two adjacent emitter regions 110 .
  • the distance between two adjacent back surface field regions 120 may be 600 ⁇ m to 1500 ⁇ m, such as but not limited to any one of 600 ⁇ m, 700 ⁇ m, 800 ⁇ m, 900 ⁇ m, 1000 ⁇ m, 1100 ⁇ m, 1200 ⁇ m, 1300 ⁇ m, 1400 ⁇ m and 1500 ⁇ m or Any range between the two enables the emitter region 110 to have an appropriate size and enables an appropriate distance between two adjacent back surface field regions 120 .
  • the above-mentioned setting method enables the solar cell 100 to have a suitable grid line density by rationally configuring the size and spacing of the emitter region 110 and the back surface field region 120, which facilitates the printing operation during the preparation process; while ensuring metal contact, It can also effectively achieve the purpose of reducing the recombination of the emitter 111 , increasing the open circuit voltage of the battery, and improving the photoelectric conversion efficiency of the battery.
  • the size of the positive electrode 131 may be 50 ⁇ m to 200 ⁇ m, such as but not limited to any one or both of 50 ⁇ m, 80 ⁇ m, 100 ⁇ m, 120 ⁇ m, 150 ⁇ m, 180 ⁇ m and 200 ⁇ m. The range between them has a better match with the emitter 111.
  • the size of the negative electrode 141 may be 40 ⁇ m to 100 ⁇ m, for example but not limited to any one of 40 ⁇ m, 60 ⁇ m, 80 ⁇ m and 100 ⁇ m or a range between any two, and the back surface field 121 has better matching.
  • the positive electrode 131 and the negative electrode 141 can be electrically connected to the emitter 111 and the back surface field 121 respectively in a conventional manner, for example, by connecting the positive electrode 131 and the negative
  • the electrodes 141 are printed on the emitter 111 and the back surface field 121 respectively.
  • the emitter 111 may be provided with an emitter contact hole 132 , and the positive electrode 131 may be electrically connected to the inner wall of the emitter contact hole 132 opened in the emitter 111 .
  • the back surface field 121 may be provided with a back surface field contact hole 142 , and the negative electrode 141 may be electrically connected to the inner wall of the back surface field contact hole 142 opened in the back surface field 121 .
  • the emitter contact hole 132 and the back surface field contact hole 142 are arranged alternately, which can not only collect current more effectively, but also enable the craftsman It is faster to identify the positive and negative electrode positions during screen printing alignment.
  • the diameters of the emitter contact hole 132 and the back surface field contact hole 142 can be 25 ⁇ m to 50 ⁇ m, such as but not limited to any one or both of 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m and 50 ⁇ m The range between them is convenient for the electrode obtained when printing to form the electrode to maintain a good electrical connection with the contact hole.
  • an appropriate contact hole density can make the electrodes have an appropriate distribution density, it can facilitate the printing operation in the manufacturing process, and can also effectively control the grid line density and the metallization area.
  • the emitter contact holes 132 may be arranged in at least one column, such as 1 to 5 columns. Wherein, a plurality of emitter contact holes 132 in each row of emitter contact holes 132 are distributed at intervals along the second preset direction b, and multiple rows of emitter contact holes 132 are distributed at intervals along the first preset direction a.
  • the back surface field contact holes 142 may be arranged in at least one column, for example, 1 to 8 columns.
  • a plurality of back surface field contact holes 142 in each row of back surface field contact holes 142 are distributed at intervals along the second predetermined direction b, and multiple rows of back surface field contact holes 142 are distributed at intervals along the first predetermined direction a.
  • the distance between the centers of two adjacent emitter contact holes 132 on each emitter 111 may be 20 ⁇ m to 80 ⁇ m, and the two adjacent back surface field contacts on each back surface
  • the center-to-center distance of the holes 142 may be 20 ⁇ m to 80 ⁇ m, such as but not limited to any one of 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m and 80 ⁇ m or a range between any two.
  • the distance between centers of two adjacent emitter contact holes 132 on each emitter 111 is 50 ⁇ m to 100 ⁇ m, such as but not limited to 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m Any one of 100 ⁇ m or any range between the two.
  • the distance between the centers of two adjacent back surface field contact holes 142 on each back surface is 20 ⁇ m to 80 ⁇ m, such as but not limited to any one of 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m and 80 ⁇ m or any two of them range between.
  • both the emitter 111 and the back surface field 121 are provided with a plurality of electrodes, it is convenient to connect the plurality of electrodes in a confluence manner.
  • the solar cell 100 may further include positive bus bars 133 and negative bus bars 143 distributed at intervals.
  • the positive bus bar 133 is electrically connected to each positive electrode 131
  • the negative bus bar 143 is electrically connected to each negative electrode 141; between the positive bus bar 133 and the negative electrode 141 and between the negative bus bar 143 and the positive electrode 131 Insulating glue (not shown) is evenly spaced between them, and the insulating glue is, for example, printed between the corresponding bus bars and electrodes, which can effectively avoid the short circuit of the positive and negative electrodes, and is easy to prepare.
  • both the positive electrode 131 and the negative electrode 141 can extend along a third predetermined direction c, the extending direction of the positive bus bar 133 and the negative bus bar 143 is perpendicular to the extending direction of the positive electrode 131, and the extending direction of the negative bus bar 143 Being perpendicular to the extension direction of the negative electrode 141 ensures that the bus bar can be more conveniently connected to multiple electrodes.
  • the solar cell 100 may further include a silicon nitride antireflection layer 160 , an aluminum oxide passivation layer 170 and a silicon nitride passivation layer 180 .
  • the silicon nitride anti-reflection layer 160 is formed on the surface of the anti-reflection texture 150 on the front side of the substrate 101 .
  • An aluminum oxide passivation layer 170 is formed on the surface of the emitter 111 and the back surface field 121 .
  • the silicon nitride passivation layer 180 is formed on the surface of the aluminum oxide passivation layer 170 .
  • the positive electrode 131 is electrically connected to the emitter 111 after penetrating the silicon nitride passivation layer 180 and the aluminum oxide passivation layer 170
  • the negative electrode 141 is connected to the emitter 111 after penetrating the silicon nitride passivation layer 180 and the aluminum oxide passivation layer 170. electrical connection.
  • the substrate 101 may be an N-type square single crystal silicon wafer.
  • the tunnel oxide layer 122 is a silicon dioxide film with a thickness of 1nm to 5nm, such as but not limited to any one of 1nm, 2nm, 3nm, 4nm and 5nm or a range between any two.
  • the thickness of the polysilicon layer 123 is 100nm to 500nm, for example but not limited to any one of 100nm, 200nm, 300nm, 400nm and 500nm or a range between any two.
  • the silicon nitride antireflection layer 160 is made of SiNx, and its thickness is 80nm to 120nm, such as but not limited to any one of 80nm, 90nm, 100nm, 110nm and 120nm or a range between any two.
  • the material of the aluminum oxide passivation layer 170 is AlOx, and its thickness is 3nm to 20nm, such as but not limited to any one of 3nm, 5nm, 8nm, 10nm, 13nm, 15nm, 18nm and 20nm or between any two scope.
  • the silicon nitride passivation layer 180 is made of SiNx with a thickness of 75nm to 150nm, such as but not limited to any one or both of 75nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm and 150nm range between.
  • the solar cell 100 has appropriate structural layers, and each structural layer has an appropriate thickness, which is beneficial to ensure the photoelectric conversion efficiency of the solar cell 100 .
  • a front surface field 190 can also be formed by shallow phosphorus diffusion, and the front surface field 190 is located between the anti-reflection suede 150 and the anti-reflection suede 150. between the silicon nitride antireflection layers 160 .
  • the minority carrier potential energy difference is formed on the front surface through the front surface field 190 to prevent the minority carriers from moving to the high recombination surface, thereby reducing the recombination of electron-hole pairs on the front surface.
  • the embodiment of the present application provides a method for manufacturing a solar cell 100, which may include:
  • Boron diffusion is performed on the substrate 101 , and a boron diffusion layer and borosilicate glass on the surface of the boron diffusion layer are formed on the surface of the substrate 101 .
  • the first surface of the substrate 101 is used as the back surface of the substrate 101, and laser grooves and boron diffusion layer etching are sequentially performed on the local area of the borosilicate glass on the back surface of the substrate 101 to form the back surface field region 120; no grooves and etching
  • the region is the emitter region 110 , and the emitter region 110 and the back surface field region 120 are configured to be distributed alternately on the back surface of the substrate 101 .
  • a tunnel oxide layer 122 is grown on the backside of the substrate 101 and then an intrinsic amorphous silicon layer is deposited.
  • Phosphorus is diffused on the substrate 101 so that the intrinsic amorphous silicon layer forms a polysilicon layer 123 made of phosphorus-doped polysilicon, and phosphosilicate glass is formed on the surface of the polysilicon layer 123 .
  • the corrosion-resistant paste is printed on the surface of the phosphosilicate glass corresponding to the back surface field region 120, and the corrosion-resistant paste is dried; the corrosion-resistant paste is soluble in alkali and insoluble in acid.
  • the phosphosilicate glass corresponding to the emitter region 110 is removed with acid.
  • the corrosion-resistant paste and the polysilicon layer 123 and the tunnel oxide layer 122 corresponding to the emitter region 110 are removed with alkali.
  • the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate 101 are removed with acid.
  • the remaining boron diffusion layer in the emitter region 110 serves as the emitter 111 .
  • the remaining tunnel oxide layer 122 and polysilicon layer 123 in the back surface field region 120 serve as the back surface field 121 .
  • the positive electrode 131 is electrically connected to the emitter 111 and the negative electrode 141 is electrically connected to the back surface field 121 .
  • the method for preparing the solar cell 100 provided in the present application can prepare the solar cell 100 as provided in the embodiment of the first aspect.
  • the emitter 111 is the remaining boron diffusion layer in the emitter region 110, and its material is boron-doped single crystal silicon.
  • the back surface field region 120 is the region after removing the boron diffusion layer. In order to fully remove the back boron diffusion and form the boron diffusion layer on the surface of the substrate 101, the groove depth of the surface field region is greater than or equal to the boron diffusion depth in the boron diffusion step.
  • the position where the tunnel oxide layer 122 grows in the back surface field region 120 is lower than the region where the emitter 111 grows in the emitter region 110, that is to say, the tunnel oxide layer 122 is close to the front side of the substrate 101 to the substrate.
  • the vertical distance from the middle of the chip is L1
  • the vertical distance from the side of the emitter 111 close to the front side of the substrate 101 to the middle of the substrate is L2, and L1 ⁇ L2.
  • the step of removing the corrosion-resistant slurry, the polysilicon layer 123 and the tunnel oxide layer 122 corresponding to the emitter region 110 with alkali may include: removing the corrosion-resistant slurry with a first alkali solution, Then, the polysilicon layer 123 and the tunnel oxide layer 122 corresponding to the emitter region 110 are removed with a second alkali solution. Wherein, the alkalinity of the first lye is smaller than that of the second lye.
  • the removal of the corrosion-resistant slurry is carried out step by step with the removal of the polysilicon layer 123 and the tunneling oxide layer 122, which facilitates the treatment of separate tanks, that is, the corrosion-resistant slurry is removed in a tank specially used for removing the corrosion-resistant slurry.
  • the removal of the polysilicon layer 123 and the tunnel oxide layer 122 is carried out in the tank where the polysilicon layer 123 and the tunnel oxide layer 122 are removed, which can effectively improve the cross contamination of the tank body.
  • the step of electrically connecting the positive electrode 131 to the emitter 111 and electrically connecting the negative electrode 141 to the back surface field 121 may include: opening an emitter contact hole 132 on the emitter 111, A region corresponding to the emitter contact hole 132 is printed with a positive electrode 131 . A back surface field contact hole 142 is opened in the back surface field 121, and a negative electrode 141 is printed in a region corresponding to the surface field contact hole.
  • the emitter contact hole 132 and the back surface field contact hole 142 also penetrate the corresponding functional layer.
  • one surface of the substrate 101 is textured before boron diffusion, and the textured surface is used as the front side of the substrate 101 .
  • This preparation method is likely to cause certain damage to the textured surface in subsequent processes such as etching and corrosion, thereby affecting the anti-reflection effect of the textured surface.
  • the second surface of the substrate 101 is used as the front surface of the substrate 101
  • the step of forming the anti-reflection texture 150 on the surface of the substrate 101 may include: removing the corrosion-resistant slurry with alkali and connecting with the emitter After the step of the polysilicon layer 123 and the tunnel oxide layer 122 corresponding to the region 110, before the step of removing the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate 101 with acid, the phosphosilicate glass and borosilicate glass on the front side of the substrate 101 are removed with acid. borosilicate glass, and then texture the front side of the substrate 101 to form anti-reflection texture 150 .
  • the texturing step is performed after the N-type region and the P-type region are prepared, which can effectively reduce the damage to the anti-reflective textured surface 150 by the previous process. Meanwhile, the texturing step is carried out before the step of removing the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate 101, and the remaining phosphosilicate glass and borosilicate glass on the back side of the substrate 101 are used as a mask to effectively prevent the texturing step from affecting the N Lesions in the P-type and P-type regions.
  • the substrate 101 may also be textured before the boron diffusion step.
  • An N-type square single crystal silicon wafer is provided as the substrate 101, and the surface of the substrate 101 is polished to remove mechanical damage.
  • the sheet resistance of the boron diffusion is 120 ⁇ /sq to 150 ⁇ /sq, for example but not limited to any one of 120 ⁇ /sq, 130 ⁇ /sq, 140 ⁇ /s and 150 ⁇ /sq or between any two scope.
  • step C Retain the borosilicate glass produced by the boron diffusion process, and use a laser to make local grooves on the borosilicate glass on one side of the substrate 101 obtained in step B.
  • the laser grooving is realized by moving and superimposing the light spot 200 to cover the entire grooving area.
  • step D Etch away the boron diffusion layer in the grooved region in step C to form the back surface field region 120; the ungrooved and etched region is the emitter region 110, and the boron diffusion layer in the remaining emitter region 110 is used as the emitter 111.
  • step D Growing a tunnel oxide layer 122 on the back surface of the substrate 101 obtained in step D and then depositing an intrinsic amorphous silicon layer.
  • PECVD Pullasma Enhanced Chemical Vapor Deposition
  • the cost of PECVD is lower, the process time is shorter, and the Plating is smaller, which is good for appearance and yield control.
  • step F Perform phosphorus diffusion on the substrate 101 obtained in step E, so that the intrinsic amorphous silicon layer is formed into a polysilicon layer 123 made of phosphorus-doped polysilicon, and phosphosilicate glass is formed on the surface of the polysilicon layer 123 .
  • the polysilicon layer 123 corresponding to the back surface field region 120 is N-type doped to form a back surface field 121 corresponding to the back surface field region 120 .
  • the printed lines correspond to the laser grooved area 300 in step C, that is, the printed lines correspond to the surface of the phosphosilicate glass formed in the back surface field area 120 in step D.
  • step G Drying the corrosion resistant paste printed in step G.
  • step F Use acid to remove the phosphosilicate glass formed by the phosphorus diffusion in step F. This step is used to remove the phosphosilicate glass corresponding to the emitter region 110 because the phosphosilicate glass in the back surface field region 120 is protected by the corrosion-resistant paste.
  • the remaining boron diffusion layer in the emitter region 110 serves as the emitter 111 ; the remaining tunnel oxide layer 122 and polysilicon layer 123 in the back surface field region 120 serve as the back surface field 121 .
  • An aluminum oxide passivation layer 170 and a silicon nitride passivation layer 180 are sequentially deposited on the back surface of the substrate 101 .
  • step N the remaining emitter 111 and the back surface field 121 are laser-opened to form the emitter contact hole 132 and the back surface field contact hole 142 .
  • a method for preparing a solar cell 100 as shown in FIG. 1 may include:
  • An N-type square single crystal silicon wafer is provided as the substrate 101, and the surface of the substrate 101 is polished to remove mechanical damage by using 20% KOH solution.
  • the sheet resistance is 120 ⁇ /sq.
  • step C Retain the borosilicate glass produced by the boron diffusion process, and use a laser to make local grooves on the borosilicate glass on one side of the substrate 101 obtained in step B.
  • the width of the grooved region is 200 ⁇ m, and the distance between two adjacent grooved regions is 1200 ⁇ m.
  • step D Etch away the boron diffusion layer in the grooved region in step C to form the back surface field region 120; the ungrooved and etched region is the emitter region 110, and the boron diffusion layer in the remaining emitter region 110 is used as the emitter 111.
  • step E Using PECVD to sequentially grow a tunnel oxide layer 122 on the back of the substrate 101 obtained in step D, and then deposit an intrinsic amorphous silicon layer.
  • the thickness of the tunneling oxide layer 122 is 1 nm, and the thickness of the intrinsic amorphous silicon layer is 200 nm.
  • step F Perform phosphorus diffusion on the substrate 101 obtained in step E, so that the intrinsic amorphous silicon layer is formed into a polysilicon layer 123 made of phosphorus-doped polysilicon, and phosphosilicate glass is formed on the surface of the polysilicon layer 123 .
  • the polysilicon layer 123 corresponding to the back surface field region 120 is N-type doped to form a back surface field 121 corresponding to the back surface field region 120 .
  • the sheet resistance is 30 ⁇ /sq.
  • the printed lines correspond to the laser grooved area 300 in step C, that is, the printed lines correspond to the surface of the phosphosilicate glass formed in the back surface field area 120 in step D.
  • step H drying the corrosion-resistant paste printed in step G, wherein the line width of the corrosion-resistant paste in the first preset direction a is 100 ⁇ m.
  • step F Use 10% chain HF solution to remove the phosphosilicate glass formed by phosphorus diffusion in step F. This step is used to remove the phosphosilicate glass corresponding to the emitter region 110 because the phosphosilicate glass in the back surface field region 120 is protected by the corrosion-resistant paste.
  • the thickness of the silicon nitride anti-reflection layer 160 is 80nm.
  • an aluminum oxide passivation layer 170 and a silicon nitride passivation layer 180 sequentially on the back side of the substrate 101 by PECVD, wherein the thickness of the aluminum oxide passivation layer 170 is 10nm, and the thickness of the silicon nitride passivation layer 180 is 75nm .
  • step N the remaining emitter 111 and the back surface field 121 are laser-opened to form the emitter contact hole 132 and the back surface field contact hole 142 .
  • Three rows of emitter contact holes 132 are distributed on each emitter 111, and the diameter of the emitter contact holes 132 is 25 ⁇ m; The center-to-center distance is 40 ⁇ m; in the second preset direction b, the center-to-center distance between two adjacent emitter contact holes 132 on each emitter 111 is 60 ⁇ m.
  • Two columns of back surface field contact holes 142 are distributed on each back surface field 121, and the diameter of the back surface field contact holes 142 is 30 ⁇ m; in the first preset direction a, two adjacent back surfaces of each back surface field 121 The distance between centers of the field contact holes 142 is 40 ⁇ m; in the second preset direction b, the distance between centers of two adjacent back surface field contact holes 142 on each back surface field 121 is 60 ⁇ m.
  • step Q Printing corresponding metal positive electrodes 131 and negative electrodes 141 on the laser opening area in step Q, followed by drying at 200°C.
  • the electrical performance of the solar cell 100 prepared in Example 1 was tested, and the photoelectric conversion efficiency can reach 23.83%, the open circuit voltage Voc can reach 700mV, the current density Jsc can reach 42.02mA/cm 2 , and the fill factor FF can reach 81%. .
  • Example 2 It differs from Example 1 in that:
  • step N and step O the following step is added, forming a layer of front surface field 190 through shallow phosphorus diffusion, and the structure of the obtained solar cell 100 is shown in FIG. 4 .
  • the front surface field 190 is formed to form a minority carrier potential energy difference on the surface, which prevents the minority carriers from moving to the high recombination surface, thereby reducing the recombination of electron-hole pairs on the front surface.
  • the electrical performance of the solar cell 100 prepared in Example 2 was tested, and the photoelectric conversion efficiency can reach 24%, the open circuit voltage Voc can reach 704mV, the current density Jsc can reach 42.05mA/cm 2 , and the fill factor FF can reach 81.07%. .
  • Example 2 It differs from Example 1 in that:
  • the width of the grooved region is 250 ⁇ m, and the distance between two adjacent grooved regions is 1400 ⁇ m.
  • Three columns of emitter contact holes 132 are distributed on each emitter 111, and the diameter of the emitter contact holes 132 is 30 ⁇ m; The center-to-center distance is 50 ⁇ m; in the second preset direction b, the center-to-center distance between two adjacent emitter contact holes 132 on each emitter 111 is 80 ⁇ m.
  • Two rows of back surface field contact holes 142 are distributed on each back surface field 121, and the diameter of the back surface field contact holes 142 is 32 ⁇ m; in the first predetermined direction a, two adjacent back surfaces of each back surface field 121 The distance between the centers of the field contact holes 142 is 50 ⁇ m; in the second predetermined direction b, the distance between the centers of two adjacent back surface field contact holes 142 on each back surface field 121 is 80 ⁇ m.
  • the electrical performance of the solar cell 100 prepared in Example 3 was tested, and the photoelectric conversion efficiency can reach 23.81%, the open circuit voltage Voc can reach 700.2mV, the current density Jsc can reach 41.96mA/cm 2 , and the fill factor FF can reach 81.03 %.
  • Example 2 It differs from Example 1 in that:
  • the KOH solution in the polishing, texturing and etching processes can be replaced by NaOH, which can save costs.
  • the electrical performance of the solar cell 100 prepared in Example 4 was tested, and the photoelectric conversion efficiency can reach 23.86%, the open circuit voltage Voc can reach 700.5mV, the current density Jsc can reach 42.03mA/cm 2 , and the fill factor FF can reach 81.05 %.
  • Example 2 It differs from Example 1 in that:
  • the sheet resistance of the boron diffusion in Step B was 150 ⁇ /sq.
  • the distance between two adjacent grooved regions is 1000 ⁇ m.
  • the design of the high-resistance dense grid lines can reduce the recombination of the emitter level on the back side while ensuring the metal contact, and increase the open circuit voltage of the solar cell.
  • the electrical performance of the solar cell 100 prepared in Example 5 was tested, and the photoelectric conversion efficiency can reach 23.98%, the open circuit voltage Voc can reach 703.4mV, the current density Jsc can reach 42.07mA/cm 2 , and the fill factor FF can reach 81.03 %.
  • Example 2 It differs from Example 1 in that:
  • the aluminum oxide passivation layer 170 can be prepared by sinking ALD (atomic layer deposition), and its thickness is 7 nm.
  • the aluminum oxide passivation layer 170 deposited in this embodiment is more electronegative and denser, which can improve the back surface of the solar cell. Passivation effect, thereby improving the open circuit voltage and photoelectric conversion efficiency of solar cells.
  • the electrical performance of the solar cell 100 prepared in Example 6 was tested, and the photoelectric conversion efficiency can reach 24.02%, the open circuit voltage Voc can reach 703.2mV, the current density Jsc can reach 42.10mA/cm 2 , and the fill factor FF can reach 81.15 %.
  • a solar cell has alternately distributed emitter regions and back surface field regions on the back of its substrate.
  • An emitter is formed in the emitter region, and the material of the emitter is boron-doped single crystal silicon.
  • a back surface field is formed in the back surface field region; the back surface field includes a stacked tunnel oxide layer and a polysilicon layer, the polysilicon layer is made of phosphorus-doped polysilicon, and the tunnel oxide layer is located between the polysilicon layer and the polysilicon layer.
  • the positive electrode of the solar cell is electrically connected to the emitter, and the negative electrode of the solar cell is electrically connected to the back surface.
  • the method for preparing the solar cell is used to realize the preparation of the solar cell with the above structure.
  • the solar cell can increase the light-receiving area of the front surface and reduce the recombination rate of electron-hole pairs, thereby effectively improving the photoelectric conversion efficiency of the solar cell. .
  • the solar cells of the present application and their fabrication methods are reproducible and can be used in a variety of industrial applications.
  • the solar cell and its preparation method of the present application can be used in the field of photovoltaic technology.

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Abstract

本申请提供一种太阳能电池及其制备方法，属于光伏技术领域。太阳能电池，其基底的背面具有交替分布的发射极区域和背表面场区域。发射极区域形成有发射极，发射极的材质为掺硼单晶硅。背表面场区域形成有背表面场；背表面场包括层叠分布的隧穿氧化层和多晶硅层，多晶硅层的材质为掺磷多晶硅，隧穿氧化层位于多晶硅层和多晶硅层之间。太阳能电池的正电极与发射极电性连接，太阳能电池的负电极于背表面场电性连接。太阳能电池的制备方法用于实现上述结构的太阳能电池的制备。该太阳能电池能够增大正面的受光面积并降低电子空穴对的复合速率，从而能够有效提高太阳能电池的光电转换效率。

Description

一种太阳能电池及其制备方法
相关申请的交叉引用
本申请要求于2021年10月27日提交中国国家知识产权局的申请号为202111256035.8、名称为“一种太阳能电池及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光伏技术领域，具体而言，涉及一种太阳能电池及其制备方法。
背景技术
太阳能电池的正面受光面积是影响其光电转换效率的重要因素，然而，常规的太阳能电池的正面存在栅线结构的遮挡，其会导致电流损失，从而会导致光电转换效率降低。
另外，对于晶硅太阳能电池来说，电池内部电子空穴对的复合决定了太阳能电池的光电转换效率，然而，常规扩散形成的扩散层存在电子空穴对复合速率大等问题，一直是制约太阳能电池效率的重要因素之一。
发明内容
本申请提供了一种太阳能电池及其制备方法，能够增大正面的受光面积并降低电子空穴对的复合速率，从而能够有效提高太阳能电池的光电转换效率。
本申请的实施例是这样实现的：
本申请的一些实施例提供一种太阳能电池，其基底的背面具有交替分布的发射极区域和背表面场区域。
发射极区域形成有发射极，发射极的材质为掺硼单晶硅。
背表面场区域形成有背表面场；背表面场包括层叠分布的隧穿氧化层和多晶硅层，多晶硅层的材质为掺磷多晶硅，隧穿氧化层位于多晶硅层和多晶硅层之间。
太阳能电池的正电极与发射极电性连接，太阳能电池的负电极于背表面场电性连接。
上述技术方案中，将连接正电极的发射极设置于基底的背面，使得基底的正面无正电极及对应的栅线结构，能够增大正面的受光面积、减小基底的正面因遮光而导致的电流损失，从而可以提高太阳电池的光电转换效率。
在基底的背面设置隧穿氧化层和材质为掺磷多晶硅的多晶硅层作为背表面场，隧穿氧化层的隧穿效应可以让电子通过而空穴无法通过，掺磷多晶硅形成钝化接触，从而能够降低电子空穴对的复合速率。
在一些可选的实施方案中，发射极区域和背表面场区域可以沿第一预设方向并排分布。
在第一预设方向上，每个背表面场区域的尺寸可以为100μm至300μm，相邻两个背表 面场区域的间距可以为600μm至1500μm。
上述技术方案中，发射极区域和背表面场区域具有合适的尺寸和间距，使得太阳能电池具有合适的栅线密度，方便在制备过程中的印刷作业；在保证金属接触的同时，还能够有效实现降低发射极的复合、提升电池的开路电压、提升电池的光电转换效率的目的。
在一些可选的实施方案中，在第一预设方向上，正电极的尺寸可以为50μm至200μm，负电极的尺寸可以为40μm至100μm。
可选地，正电极可以与开设于发射极的发射极接触孔内壁电性连接，负电极可以与开设于背表面场的背表面场接触孔内壁电性连接；发射极接触孔和背表面场接触孔的直径均可以为25μm至50μm。
可选地，在第一预设方向上，每个发射极上相邻两个发射极接触孔的中心间距为可以20μm至80μm，每个背表面上相邻两个背表面场接触孔的中心间距可以为20μm至80μm。
可选地，每个发射极区域和背表面场区域均可以沿第二预设方向延伸，第二预设方向可以与第一预设方向垂直；在第二预设方向上，每个发射极上相邻两个发射极接触孔的中心间距可以为50μm至100μm，每个背表面上相邻两个背表面场接触孔的中心间距可以为20μm至80μm。
可选地，所述发射极和所述背表面场可以相互交错设置，使得所述发射极接触孔和所述背表面场接触孔相互交错设置。
可选地，在每个发射极区域，所述发射极接触孔可以设置为至少一列，其中，每列发射极接触孔中的多个发射极接触孔沿第二预设方向间隔分布，多列发射极接触孔沿第一预设方向间隔分布；在每个背表面场区域，所述背表面场接触孔可以设置为至少一列，其中，每列背表面场接触孔中的多个背表面场接触孔沿第二预设方向间隔分布，多列背表面场接触孔沿第一预设方向间隔分布。
上述技术方案中，电极及接触孔具有合适的规格和间距，与发射极及背表面场有较好的匹配性，且能够有效控制太阳能电池的金属化面积，同时方便在制备过程中的印刷作业。
在一些可选的实施方案中，隧穿氧化层可以为二氧化硅薄膜，且厚度可以为1nm至5nm；可选地，隧穿氧化层的厚度可以为1nm至3nm。
和/或，多晶硅层的厚度可以为100nm至500nm。
在一些可选的实施方案中，太阳能电池还可以包括氮化硅减反层、氧化铝钝化层以及氮化硅钝化层。
氮化硅减反层可以形成于基底的正面的减反绒面的表面。
氧化铝钝化层可以形成于发射极和背表面场的表面。
氮化硅钝化层可以形成于氧化铝钝化层的表面。
正电极贯穿氮化硅钝化层和氧化铝钝化层后与发射极电性连接，负电极贯穿氮化硅钝化层和氧化铝钝化层后与发射极电性连接。
可选地，氮化硅减反层的厚度可以为80nm至120nm。
可选地，氧化铝钝化层的厚度可以为3nm至20nm。
可选地，氮化硅钝化层的厚度可以为75nm至150nm。
可选地，在所述减反绒面的表面还可以通过浅磷扩散形成有前表面场，所述前表面场位于所述减反绒面和所述氮化硅减反层之间。
上述技术方案中，太阳能电池具有合适的结构层，且各结构层具有合适的厚度，有利于保证太阳能电池的光电转换效率。
在一些可选的实施方案中，太阳能电池还可以包括间隔分布的正极汇流条和负极汇流条。
正极汇流条可以与每个正电极均电性连接，负极汇流条可以与每个负电极均电性连接；正极汇流条与负电极之间以及负极汇流条与正电极之间均间隔有绝缘胶。
可选地，所述正电极和所述负电极可以均沿第三预设方向延伸，所述正极汇流条和所述负极汇流条的延伸方向垂直于所述正电极的延伸方向，所述负极汇流条的延伸方向垂直于所述负电极的延伸方向。
上述技术方案中，通过汇流条能够方便地进行多个电极的汇流；绝缘胶的设置有效避免正负极短路，且制备方便。
本申请的另一些实施例提供一种太阳能电池的制备方法，可以包括：
对基底进行硼扩散，在基底的表面形成硼扩散层及位于硼扩散层表面的硼硅玻璃。
将基底的第一表面作为基底的背面，在基底的背面的硼硅玻璃的局部区域依次进行激光开槽以及硼扩散层刻蚀，形成背表面场区域；未开槽和刻蚀的区域为发射极区域，发射极区域和背表面场区域被配置为在基底的背面交替分布。
在基底的背面生长隧穿氧化层然后沉积本征非晶硅层。
对基底进行磷扩散，以使本征非晶硅层形成材质为掺磷多晶硅的多晶硅层，并在多晶硅层表面生成磷硅玻璃。
在背表面场区域对应的磷硅玻璃表面印刷耐腐蚀浆料，并烘干耐腐蚀浆料；耐腐蚀浆料溶于碱且不溶于酸。
用酸去除发射极区域对应的磷硅玻璃。
用碱去除耐腐蚀浆料以及与发射极区域对应的多晶硅层和隧穿氧化层。
用酸去除基底的背面剩余的磷硅玻璃和硼硅玻璃。
发射极区域剩余材质的硼扩散层作为发射极。背表面场区域剩余的隧穿氧化层和多晶 硅层作为背表面场。
将正电极与发射极电性连接并将负电极与背表面场电性连接。
上述技术方案中，通过扩散形成硼硅玻璃(BSG)和磷硅玻璃(PSG)作为掩膜，同时通过局部激光开槽刻蚀和印刷浆料，能够形成如的上述一些实施例提供的太阳能电池的结构，能够增大正面的受光面积并降低电子空穴对的复合速率，从而能够有效提高太阳能电池的光电转换效率。
在一些可选的实施方案中，用碱去除耐腐蚀浆料以及与发射极区域对应的多晶硅层和隧穿氧化层的步骤可以包括：
先用第一碱液去除耐腐蚀浆料，然后用第二碱液去除发射极区域对应的多晶硅层和隧穿氧化层。
其中，第一碱液的碱性小于第二碱液的碱性。
上述技术方案中，将耐腐蚀浆料的去除步骤同多晶硅层和隧穿氧化层的去除分步骤进行，便于分槽体处理，能有效改善槽体交叉污染的情况。
采用碱性相对较大的第二碱液，有利于更充分地去除发射极区域对应的多晶硅层和隧穿氧化层。
在一些可选的实施方案中，将正电极与发射极电性连接并将负电极与背表面场电性连接的步骤可以包括：
在发射极开设发射极接触孔，在与发射极接触孔对应的区域印刷正电极。
在背表面场开设背表面场接触孔，在与表面场接触孔对应的区域印刷负电极。
上述技术方案中，通过开孔后印刷金属浆料的方式形成电极，有利于减小金属化的面积，从而能够减少电池背面的金属复合、提高光电转换效率。
在一些可选的实施方案中，将基底的第二表面作为基底的正面，在基底的表面形成减反绒面的步骤可以包括：
在用碱去除耐腐蚀浆料以及与发射极区域对应的多晶硅层和隧穿氧化层的步骤之后，在用酸去除基底的背面剩余的磷硅玻璃和硼硅玻璃的步骤之前，用酸去除基底的正面的磷硅玻璃和硼硅玻璃，然后对基底的正面进行制绒处理形成减反绒面。
上述技术方案中，制绒步骤在N型区域和P型区域制备完成后进行，能够有效降低前序工艺对减反绒面的损伤。同时，制绒步骤在去除基底的背面剩余的磷硅玻璃和硼硅玻璃的步骤之前进行，利用基底的背面剩余的磷硅玻璃和硼硅玻璃作为掩模，有效防止制绒步骤对N型区域和P型区域的损伤。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本申请的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1为本申请实施例提供的第一种太阳能电池的结构示意图；
图2为本申请实施例提供的太阳能电池的背面的分区及开槽结构示意图；
图3为本申请实施例提供的太阳能电池的电极的连接示意图；
图4为本申请实施例提供的第二种太阳能电池的结构示意图；
图5为本申请实施例提供的太阳能电池的制备方法中激光开槽的示意图。
图标：100-太阳能电池；101-基底；110-发射极区域；111-发射极；120-背表面场区域；121-背表面场；122-隧穿氧化层；123-多晶硅层；131-正电极；132-发射极接触孔；133-正极汇流条；141-负电极；142-背表面场接触孔；143-负极汇流条；150-减反绒面；160-氮化硅减反层；170-氧化铝钝化层；180-氮化硅钝化层；190-前表面场；200-光斑；300-激光开槽区域；a-第一预设方向；b-第二预设方向；c-第三预设方向。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。通常在此处附图中描述和示出的本申请实施例的组件可以以各种不同的配置来布置和设计。
因此，以下对在附图中提供的本申请的实施例的详细描述并非旨在限制要求保护的本申请的范围，而是仅仅表示本申请的选定实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步定义和解释。
在本申请的描述中，需要说明的是，术语“正面”、“背面”、“中心”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，或者是该申请产品使用时惯常摆放的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
此外，术语“第一”、“第二”等仅用于区分描述，而不能理解为指示或暗示相对重要性。
此外，术语“垂直”、“平行”等术语并不表示要求部件绝对垂直或平行，而是可以稍 微倾斜。
在本申请的实施例中，未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
另外，需要说明的是，本申请中的“和/或”，如“特征1和/或特征2”，均是指可以单独地为“特征1”、单独地为“特征2”、“特征1”加“特征2”，该三种情况。
下面对本申请实施例的结构及方法进行具体说明。
请参阅图1，第一方面，本申请实施例提供一种太阳能电池100，其基底101的背面具有交替分布的发射极区域110和背表面场区域120。
为了便于对本申请的技术方案进行更清楚地阐述，作出如下定义：
请参阅图1和图2，发射极区域110和背表面场区域120交替并排分布的方向为第一预设方向a，每个发射极区域110和背表面场区域120的延伸方向为第二预设方向b；该第一预设方向a和第二预设方向b相互垂直，且二者均与基底101的表面平行。太阳能电池100的厚度方向为第三预设方向c，该第三预设方向c与基底101的表面垂直。
发射极区域110形成有发射极111，发射极111的材质为掺硼单晶硅。背表面场区域120形成有背表面场121；背表面场121包括层叠分布的隧穿氧化层122和多晶硅层123，多晶硅层123的材质为掺磷多晶硅，隧穿氧化层122位于多晶硅层123和多晶硅层123之间。太阳能电池100的正电极131与发射极111电性连接，太阳能电池100的负电极141于背表面场121电性连接。
本申请提供的太阳能电池100，将连接正电极131的发射极111可以设置于基底101的背面，使得基底101的正面无正电极131及对应的栅线结构，能够增大正面的受光面积、减小基底101的正面因遮光而导致的电流损失，从而可以提高太阳电池的光电转换效率。在基底101的背面设置隧穿氧化层122和材质为掺磷多晶硅的多晶硅层123作为背表面场121，隧穿氧化层122的隧穿效应可以让电子通过而空穴无法通过，掺磷多晶硅形成钝化接触，从而能够降低电子空穴对的复合速率。
在一些示例性的实施方案中，在第一预设方向a上，每个背表面场区域120的尺寸可以为100μm至300μm，例如但不限于为100μm、150μm、200μm、250μm和300μm中的任意一者或者任意两者之间的范围，使得背表面场区域120具有合适的尺寸，并使得相邻的两个发射极区域110之间具有合适的间距。
可选地，相邻两个背表面场区域120的间距可以为600μm至1500μm，例如但不限于600μm、700μm、800μm、900μm、1000μm、1100μm、1200μm、1300μm、1400μm和1500μm中的任意一者或者任意两者之间的范围，使得发射极区域110具有合适的尺寸，并使得相邻的两个背表面场区域120之间具有合适的间距。
上述的设置方式，通过合理地配置发射极区域110和背表面场区域120的尺寸和间距使得太阳能电池100具有合适的栅线密度，方便在制备过程中的印刷作业；在保证金属接触的同时，还能够有效实现降低发射极111的复合、提升电池的开路电压、提升电池的光电转换效率的目的。
可选地，在第一预设方向a上，正电极131的尺寸可以为50μm至200μm，例如但不限于为50μm、80μm、100μm、120μm、150μm、180μm和200μm中的任意一者或者任意两者之间的范围，与发射极111有较好的匹配性。在第一预设方向a上，负电极141的尺寸可以为40μm至100μm，例如但不限于为40μm、60μm、80μm和100μm中的任意一者或者任意两者之间的范围，与背表面场121有较好的匹配性。
可以理解的是，在本申请提供的太阳能电池100中，正电极131和负电极141可以按照常规的方式分别同发射极111及背表面场121进行电性连接，例如通过将正电极131和负电极141分别印刷在发射极111及背表面场121。
作为一种示例，发射极111可以开设有发射极接触孔132，正电极131可以与开设于发射极111的发射极接触孔132内壁电性连接。背表面场121可以开设有背表面场接触孔142，负电极141可以与开设于背表面场121的背表面场接触孔142内壁电性连接。本申请中，由于发射极111和背表面场121相互交错设置，使得发射极接触孔132和背表面场接触孔142相互交错设置，其不仅能够更有效地收集电流，还能够使工艺人员在丝网印刷对准的时候较快速识别正负极位置。
可选地，发射极接触孔132和背表面场接触孔142的直径均可以为25μm至50μm，例如但不限于为25μm、30μm、35μm、40μm、45μm和50μm中的任意一者或者任意两者之间的范围，方便印刷形成电极时得到的电极能够与接触孔保持较好的电性连接关系。
考虑到合适的接触孔密度能够使得电极具有合适的分布密度，其能够方便在制备过程中的印刷作业，也能够有效地控制栅线密度及金属化面积。
示例性地，在每个发射极区域110，发射极接触孔132可以设置为至少一列，例如为1至5列。其中，每列发射极接触孔132中的多个发射极接触孔132沿第二预设方向b间隔分布，多列发射极接触孔132沿第一预设方向a间隔分布。在每个背表面场区域120，背表面场接触孔142可以设置为至少一列，例如为1至8列。其中，每列背表面场接触孔142中的多个背表面场接触孔142沿第二预设方向b间隔分布，多列背表面场接触孔142沿第一预设方向a间隔分布。
可选地，在第一预设方向a上，每个发射极111上相邻两个发射极接触孔132的中心间距可以为20μm至80μm，每个背表面上相邻两个背表面场接触孔142的中心间距可以为20μm至80μm，例如但不限于20μm、30μm、40μm、50μm、60μm、70μm和80μm中的任 意一者或者任意两者之间的范围。
可选地，在第二预设方向b上，每个发射极111上相邻两个发射极接触孔132的中心间距为50μm至100μm，例如但不限于为50μm、60μm、70μm、80μm、90μm和100μm中的任意一者或者任意两者之间的范围。每个背表面上相邻两个背表面场接触孔142的中心间距为20μm至80μm，例如但不限于20μm、30μm、40μm、50μm、60μm、70μm和80μm中的任意一者或者任意两者之间的范围。
考虑到发射极111和背表面场121均设置有多个电极，采用汇流的方式方便将多个电极进行连接。
请参阅图3，作为示例，太阳能电池100还可以包括间隔分布的正极汇流条133和负极汇流条143。正极汇流条133与每个正电极131均电性连接，负极汇流条143与每个负电极141均电性连接；正极汇流条133与负电极141之间以及负极汇流条143与正电极131之间均间隔有绝缘胶(图未示)，该绝缘胶例如印刷在相应的汇流条和电极之间，其能有效避免正负极短路，且制备方便。
可选地，正电极131和负电极141均可以沿第三预设方向c延伸，正极汇流条133和负极汇流条143的延伸方向垂直于正电极131的延伸方向，负极汇流条143的延伸方向垂直于负电极141的延伸方向，保证汇流条能够更方便地同多个电极进行连接。
可以理解的是，在本申请提供的太阳能电池100中，可以根据本领域公知的方式，再增加其他的功能层。另外，关于各功能层的材质和厚度等要求，可以根据设计需要或者本领域公知的标准进行设置。
在一些示例性的实施方案中，太阳能电池100还可以包括氮化硅减反层160、氧化铝钝化层170以及氮化硅钝化层180。氮化硅减反层160形成于基底101的正面的减反绒面150的表面。氧化铝钝化层170形成于发射极111和背表面场121的表面。氮化硅钝化层180形成于氧化铝钝化层170的表面。正电极131贯穿氮化硅钝化层180和氧化铝钝化层170后与发射极111电性连接，负电极141贯穿氮化硅钝化层180和氧化铝钝化层170后与发射极111电性连接。
关于各功能层的厚度和材质，在以下作出示例：
基底101可以为N型方单晶硅片。
隧穿氧化层122为二氧化硅薄膜，其厚度为1nm至5nm例如但不限于为1nm、2nm、3nm、4nm和5nm中的任意一者或者任意两者之间的范围。
多晶硅层123的厚度为100nm至500nm，例如但不限于为100nm、200nm、300nm、400nm和500nm中的任意一者或者任意两者之间的范围。
氮化硅减反层160的材质为SiNx，其厚度为80nm至120nm，例如但不限于为80nm、 90nm、100nm、110nm和120nm中的任意一者或者任意两者之间的范围。
氧化铝钝化层170的材质为AlOx，其厚度为3nm至20nm，例如但不限于为3nm、5nm、8nm、10nm、13nm、15nm、18nm和20nm中的任意一者或者任意两者之间的范围。
氮化硅钝化层180的材质为SiNx，其厚度为75nm至150nm，例如但不限于为75nm、80nm、90nm、100nm、110nm、120nm、130nm、140nm和150nm中的任意一者或者任意两者之间的范围。
上述技术方案中，太阳能电池100具有合适的结构层，且各结构层具有合适的厚度，有利于保证太阳能电池100的光电转换效率。
请参阅图4，在一些可选的实施方案中，在减反绒面150的表面还可以通过浅磷扩散形成有前表面场190(FSF)，该前表面场190位于减反绒面150和氮化硅减反层160之间。通过前表面场190在正面形成少子电势能差，阻挡少子向高复合表面移动，从而减少了前表面电子空穴对的复合。
第二方面，本申请实施例提供一种太阳能电池100的制备方法，可以包括：
对基底101进行硼扩散，在基底101的表面形成硼扩散层及位于硼扩散层表面的硼硅玻璃。
将基底101的第一表面作为基底101的背面，在基底101的背面的硼硅玻璃的局部区域依次进行激光开槽以及硼扩散层刻蚀，形成背表面场区域120；未开槽和刻蚀的区域为发射极区域110，发射极区域110和背表面场区域120被配置为在基底101的背面交替分布。
在基底101的背面生长隧穿氧化层122然后沉积本征非晶硅层。
对基底101进行磷扩散，以使本征非晶硅层形成材质为掺磷多晶硅的多晶硅层123，并在多晶硅层123表面生成磷硅玻璃。
在背表面场区域120对应的磷硅玻璃表面印刷耐腐蚀浆料，并烘干耐腐蚀浆料；耐腐蚀浆料溶于碱且不溶于酸。
用酸去除发射极区域110对应的磷硅玻璃。
用碱去除耐腐蚀浆料以及与发射极区域110对应的多晶硅层123和隧穿氧化层122。
用酸去除基底101的背面剩余的磷硅玻璃和硼硅玻璃。
发射极区域110剩余的硼扩散层作为发射极111。背表面场区域120剩余的隧穿氧化层122和多晶硅层123作为背表面场121。
将正电极131与发射极111电性连接并将负电极141与背表面场121电性连接。
本申请提供的太阳能电池100的制备方法，能够制备得到如第一方面实施例提供的太阳能电池100。
需要说明的是，在本申请中，发射极111为发射极区域110剩余的硼扩散层，其材质 为掺硼单晶硅。背表面场区域120为去除硼扩散层后的区域，为了充分去除背硼扩散在基底101的表面的形成硼扩散层，表面场区域的开槽深度≥硼扩散步骤中的硼扩散深度。
作为一种示例，背表面场区域120生长隧穿氧化层122的位置低于发射极区域110生长发射极111的区域，即是说，隧穿氧化层122靠近基底101的正面的一侧到基片的中部的垂直距离为L1，发射极111靠近基底101的正面的一侧到基片的中部的垂直距离为L2，L1＜L2。
在一些示例性的实施方案中，用碱去除耐腐蚀浆料以及与发射极区域110对应的多晶硅层123和隧穿氧化层122的步骤可以包括：先用第一碱液去除耐腐蚀浆料，然后用第二碱液去除发射极区域110对应的多晶硅层123和隧穿氧化层122。其中，第一碱液的碱性小于第二碱液的碱性。
上述技术方案中，将耐腐蚀浆料的去除同多晶硅层123和隧穿氧化层122的去除分步骤进行，便于分槽体处理，即在去除专门去除耐腐蚀浆料的槽中进行耐腐蚀浆料的去除，并在去除多晶硅层123和隧穿氧化层122的槽中进行多晶硅层123和隧穿氧化层122的去除，能有效改善槽体交叉污染的情况。
在一些示例性的实施方案中，将正电极131与发射极111电性连接并将负电极141与背表面场121电性连接的步骤可以包括：在发射极111开设发射极接触孔132，在与发射极接触孔132对应的区域印刷正电极131。在背表面场121开设背表面场接触孔142，在与表面场接触孔对应的区域印刷负电极141。当然，在基底101的背面还设置有其他功能层的实施方案中，该发射极接触孔132和背表面场接触孔142还贯穿对应的功能层。
可以理解的是，在本申请提供的太阳能电池100的制备方法中，可以根据本领域公知的方式再增加其他的功能层，并按照本领域公知的方法进行对应的功能层的设置。
在常规的制备方法中，通常在硼扩散之前对基底101的一个表面进行制绒处理，并将制绒面作为基底101的正面。该制备方法在后续的刻蚀和腐蚀等工艺中，容易对制绒面造成一定的损伤，从而影响制绒面的减反射效果。
在一些示例性的实施方案中，将基底101的第二表面作为基底101的正面，在基底101的表面形成减反绒面150的步骤可以包括：在用碱去除耐腐蚀浆料以及与发射极区域110对应的多晶硅层123和隧穿氧化层122的步骤之后，在用酸去除基底101的背面剩余的磷硅玻璃和硼硅玻璃的步骤之前，用酸去除基底101的正面的磷硅玻璃和硼硅玻璃，然后对基底101的正面进行制绒处理形成减反绒面150。
上述技术方案中，制绒步骤在N型区域和P型区域制备完成后进行，能够有效降低前序工艺对减反绒面150的损伤。同时，制绒步骤在去除基底101的背面剩余的磷硅玻璃和硼硅玻璃的步骤之前进行，利用基底101的背面剩余的磷硅玻璃和硼硅玻璃作为掩模，有 效防止制绒步骤对N型区域和P型区域的损伤。当然，在其他实施方案中，也可以在硼扩散步骤之前对基底101进行制绒处理。
基于设置其他功能层的考虑，以下对太阳能电池100的制备方法做出一种示例，其包括以下步骤:
A.提供一种N型方单晶硅片作为基底101，对基底101的表面进行去除机械损伤的抛光处理。
B.对硅片进行双面硼扩散，以在基底101的两侧表面形成硼扩散层及位于硼扩散层表面的硼硅玻璃。可选地，硼扩散的方块电阻为120Ω/sq至150Ω/sq，例如但不限于为120Ω/sq、130Ω/sq、140Ω/s和150Ω/sq中的任意一者或者任意两者之间的范围。
C.保留硼扩散过程生成的硼硅玻璃，使用激光对步骤B中得到的基底101的其中一面的硼硅玻璃进行局部区域开槽。其中，请参阅图5，激光开槽通过光斑200移动叠加至覆盖整个开槽区域实现。
D.刻蚀掉步骤C中开槽区域的硼扩散层，形成背表面场区域120；未开槽和刻蚀的区域为发射极区域110，剩余的发射极区域110的硼扩散层作为发射极111。
E.在步骤D得到的基底101的背面生长隧穿氧化层122然后沉积本征非晶硅层。示例性地，其采用PECVD(等离子体增强化学的气相沉积法)的方式，相比于传统的LPCVD(低压力化学气相沉积法)方式，PECVD的方式成本更低、工艺时间更短，且绕镀更小，有利于外观和良率的控制。
F.对步骤E得到的基底101进行磷扩散，以使本征非晶硅层形成材质为掺磷多晶硅的多晶硅层123，并在多晶硅层123表面生成磷硅玻璃。背表面场区域120对应的多晶硅层123实现N型掺杂，形成与背表面场区域120对应的背表面场121。
G.在基底101的背面印刷耐腐蚀性浆料，印刷线条与步骤C中激光开槽区域300对应，即印刷线条在步骤D形成的背表面场区域120对应的磷硅玻璃表面。
H.烘干步骤G中印刷的耐腐蚀浆料。
I.用酸对步骤F中磷扩散生成的磷硅玻璃进行去除。由于背表面场区域120的磷硅玻璃被耐腐蚀性浆料保护而不会被去除掉，因此该步骤用于去除发射极区域110对应的磷硅玻璃。
J.用碱去除步骤G中印刷的耐腐蚀性浆料。
K.用碱去除背面由步骤E和F中生长的隧穿氧化层122和多晶硅层123。由于背表面场区域120的多晶硅层123和隧穿氧化层122被步骤I中保留的磷硅玻璃保护而不会被去除掉，因此该步骤用于去除发射极区域110对应的多晶硅层123和隧穿氧化层122。
L.去除正面因步骤B和F中扩散分别生成的磷硅玻璃和硼硅玻璃。
M.保留背面剩余的由步骤B和F中扩散分别生成的磷硅玻璃和硼硅玻璃作为背面掩膜，使用制绒液对基底101的正面进行制绒处理，形成减反绒面150。
N.去除基底101的背面的磷硅玻璃和硼硅玻璃，并对基底101进行化学清洗。发射极区域110剩余的硼扩散层作为发射极111；背表面场区域120剩余的隧穿氧化层122和多晶硅层123作为背表面场121。
O.在步骤M形成的减反绒面150上镀氮化硅减反层160。
P.在基底101的背面依次沉积氧化铝钝化层170和氮化硅钝化层180。
Q.分别在步骤N剩余的发射极111和背表面场121进行激光开孔，形成发射极接触孔132和背表面场接触孔142。
R.在步骤Q中的激光开孔区域印刷相应的金属的正电极131和负电极141。
S.在背面印刷绝缘胶防止正电极131和负电极141短路。
T.在背面印刷金属正电极131汇流条和负电极141汇流条。
以下结合实施例对本申请的特征和性能作进一步的详细描述。
实施例1
一种如图1所示的太阳能电池100的制备方法，可以包括：
A.提供一种N型方单晶硅片作为基底101，使用20％KOH溶液对基底101的表面进行去除机械损伤的抛光处理。
B.对硅片进行双面硼扩散，以在基底101的两侧表面形成硼扩散层及位于硼扩散层表面的硼硅玻璃。
其中，方块电阻为120Ω/sq。
C.保留硼扩散过程生成的硼硅玻璃，使用激光对步骤B中得到的基底101的其中一面的硼硅玻璃进行局部区域开槽。
其中，在第一预设方向a上，开槽区域的宽度为200μm，相邻两个开槽区域的间距为1200μm。
D.刻蚀掉步骤C中开槽区域的硼扩散层，形成背表面场区域120；未开槽和刻蚀的区域为发射极区域110，剩余的发射极区域110的硼扩散层作为发射极111。
E.采用PECVD的方式在步骤D得到的基底101的背面依次生长隧穿氧化层122然后沉积本征非晶硅层。
其中，隧穿氧化层122的厚度为1nm，本征非晶硅层的厚度为200nm。
F.对步骤E得到的基底101进行磷扩散，以使本征非晶硅层形成材质为掺磷多晶硅的多晶硅层123，并在多晶硅层123表面生成磷硅玻璃。背表面场区域120对应的多晶硅层123实现N型掺杂，形成与背表面场区域120对应的背表面场121。
其中，方块电阻为30Ω/sq。
G.在基底101的背面印刷耐腐蚀性浆料，印刷线条与步骤C中激光开槽区域300对应，即印刷线条在步骤D形成的背表面场区域120对应的磷硅玻璃表面。
H.烘干步骤G中印刷的耐腐蚀浆料，其中，耐腐蚀浆料在第一预设方向a上的线宽为100μm。
I.用10％浓度的链式HF溶液对步骤F中磷扩散生成的磷硅玻璃进行去除。由于背表面场区域120的磷硅玻璃被耐腐蚀性浆料保护而不会被去除掉，因此该步骤用于去除发射极区域110对应的磷硅玻璃。
J.用5％浓度的KOH溶液去除步骤G中印刷的耐腐蚀性浆料。
K.用10％浓度的KOH溶液去除背面由步骤E和F中生长的隧穿氧化层122和多晶硅层123。由于背表面场区域120的多晶硅层123和隧穿氧化层122被步骤I中保留的磷硅玻璃保护而不会被去除掉，因此该步骤用于去除发射极区域110对应的多晶硅层123和隧穿氧化层122。
L.用10％浓度的链式HF溶液去除正面因步骤B和F中扩散分别生成的磷硅玻璃和硼硅玻璃。
M.保留背面剩余的由步骤B和F中扩散分别生成的磷硅玻璃和硼硅玻璃作为背面掩膜，使用制绒液对基底101的正面进行制绒处理，形成减反绒面150。
N.用10％浓度的链式HF溶液去除基底101的背面的磷硅玻璃和硼硅玻璃，并对基底101进行化学清洗。发射极区域110剩余的硼扩散层作为发射极111；背表面场区域120剩余的隧穿氧化层122和多晶硅层123作为背表面场121。
O.用PECVD方式在步骤M形成的减反绒面150上镀氮化硅减反层160，氮化硅减反层160的厚度为80nm。
P.用PECVD方式在基底101的背面依次沉积氧化铝钝化层170和氮化硅钝化层180，其中氧化铝钝化层170的厚度为10nm，氮化硅钝化层180的厚度为75nm。
Q.分别在步骤N剩余的发射极111和背表面场121进行激光开孔，形成发射极接触孔132和背表面场接触孔142。
在每个发射极111分布3列发射极接触孔132，发射极接触孔132的直径为25μm；在第一预设方向a上，每个发射极111上相邻两个发射极接触孔132的中心间距为40μm；在第二预设方向b上，每个发射极111上相邻两个发射极接触孔132的中心间距为60μm。
在每个背表面场121分布2列背表面场接触孔142，背表面场接触孔142的直径为30μm；在第一预设方向a上，每个背表面场121上相邻两个背表面场接触孔142的中心间距为40μm；在第二预设方向b上，每个背表面场121上相邻两个背表面场接触孔142的中心间距为60μm。
R.在步骤Q中的激光开孔区域印刷相应的金属的正电极131和负电极141，随后200℃烘干。
S.在背面印刷绝缘胶防止正电极131和负电极141短路，随后200℃烘干。
T.在背面印刷金属正电极131汇流条和负电极141汇流条，最后进入烧结炉进行700℃烧结。
对实施例1制得的太阳能电池100的电性能进行检测，光电转换效率能够达到23.83％，开路电压Voc能够达到700mV，电流密度Jsc能够达到42.02mA/cm 2，且填充因子FF能够达到81％。
实施例2
其与实施例1的不同之处在于：
在步骤N与步骤O增加了如下步骤，通过浅磷扩散形成一层前表面场190，其得到的太阳能电池100的结构如图4所示。
实施例2中形成了前表面场190，在表面形成少子电势能差，阻挡少子向高复合表面移动，从而减少了前表面电子空穴对的复合。
对实施例2制得的太阳能电池100的电性能进行检测，光电转换效率能够达到24％，开路电压Voc能够达到704mV，电流密度Jsc能够达到42.05mA/cm 2，且填充因子FF能够达到81.07％。
实施例3
其与实施例1的不同之处在于：
在第一预设方向a上，开槽区域的宽度为250μm，相邻两个开槽区域的间距为1400μm。
在每个发射极111分布3列发射极接触孔132，发射极接触孔132的直径为30μm；在第一预设方向a上，每个发射极111上相邻两个发射极接触孔132的中心间距为50μm；在第二预设方向b上，每个发射极111上相邻两个发射极接触孔132的中心间距为80μm。
在每个背表面场121分布2列背表面场接触孔142，背表面场接触孔142的直径为32μm；在第一预设方向a上，每个背表面场121上相邻两个背表面场接触孔142的中心间距为50μm；在第二预设方向b上，每个背表面场121上相邻两个背表面场接触孔142的中心间距为80μm。
在本实施例中，既能够保证了足够少的金属化面积，又增加了后续印刷对准的宽度，降低了印刷的难度。
对实施例3制得的太阳能电池100的电性能进行检测，光电转换效率能够达到23.81％，开路电压Voc能够达到700.2mV，电流密度Jsc能够达到41.96mA/cm 2，且填充因子FF能 够达到81.03％。
实施例4
其与实施例1的不同之处在于：
抛光、制绒和刻蚀制程中的KOH溶液可以使用NaOH代替，能节省成本。
对实施例4制得的太阳能电池100的电性能进行检测，光电转换效率能够达到23.86％，开路电压Voc能够达到700.5mV，电流密度Jsc能够达到42.03mA/cm 2，且填充因子FF能够达到81.05％。
实施例5
其与实施例1的不同之处在于：
步骤B中的硼扩散的方块电阻为150Ω/sq。
在第一预设方向a上，相邻两个开槽区域的间距为1000μm。
在本实施例中，高阻密栅线的设计能够在保证金属接触的同时降低背面的发射级的复合，提升太阳电池的开路电压。
对实施例5制得的太阳能电池100的电性能进行检测，光电转换效率能够达到23.98％，开路电压Voc能够达到703.4mV，电流密度Jsc能够达到42.07mA/cm 2，且填充因子FF能够达到81.03％。
实施例6
其与实施例1的不同之处在于：
步骤P中可以使用沉ALD(原子层沉积)的方式制备氧化铝钝化层170，其厚度为7nm。
在本实施例中，相比于PECVD方式沉积得到的氧化铝钝化层170，本实施例沉积得到的氧化铝钝化层170的负电性更强、致密性更好，能够提升太阳电池的背面钝化效果，从而提升太阳电池的开路电压和光电转换效率。
对实施例6制得的太阳能电池100的电性能进行检测，光电转换效率能够达到24.02％，开路电压Voc能够达到703.2mV，电流密度Jsc能够达到42.10mA/cm 2，且填充因子FF能够达到81.15％。
以上仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。
工业实用性
本申请提供了一种太阳能电池及其制备方法，属于光伏技术领域。太阳能电池，其基底的背面具有交替分布的发射极区域和背表面场区域。发射极区域形成有发射极，发射极的材质为掺硼单晶硅。背表面场区域形成有背表面场；背表面场包括层叠分布的隧穿氧化层和多晶硅层，多晶硅层的材质为掺磷多晶硅，隧穿氧化层位于多晶硅层和多晶硅层之间。太阳能电池的正电极与发射极电性连接，太阳能电池的负电极于背表面场电性连接。太阳能电池的制备方法用于实现上述结构的太阳能电池的制备。该太阳能电池能够增大正面的受光面积并降低电子空穴对的复合速率，从而能够有效提高太阳能电池的光电转换效率。。
此外，可以理解的是，本申请的太阳能电池及其制备方法是可以重现的，并且可以用在多种工业应用中。例如，本申请的太阳能电池及其制备方法可以用于光伏技术领域。

Claims (14)

  1. 一种太阳能电池，其特征在于，其基底的背面具有交替分布的发射极区域和背表面场区域；
    所述发射极区域形成有发射极，所述发射极的材质为掺硼单晶硅；
    所述背表面场区域形成有背表面场；所述背表面场包括层叠分布的隧穿氧化层和多晶硅层，所述多晶硅层的材质为掺磷多晶硅，所述隧穿氧化层位于所述多晶硅层和所述多晶硅层之间；
    所述太阳能电池的正电极与所述发射极电性连接，所述太阳能电池的负电极于所述背表面场电性连接。
  2. 根据权利要求1所述的太阳能电池，其特征在于，所述发射极区域和所述背表面场区域沿第一预设方向并排分布；
    在所述第一预设方向上，每个所述背表面场区域的尺寸为100μm至300μm，相邻两个所述背表面场区域的间距为600μm至1500μm。
  3. 根据权利要求2所述的太阳能电池，其特征在于，在所述第一预设方向上，所述正电极的尺寸为50μm至200μm，所述负电极的尺寸为40μm至100μm；
    可选地，所述正电极与开设于所述发射极的发射极接触孔内壁电性连接，所述负电极与开设于所述背表面场的背表面场接触孔内壁电性连接；所述发射极接触孔和所述背表面场接触孔的直径均为25μm至50μm；
    可选地，在所述第一预设方向上，每个所述发射极上相邻两个所述发射极接触孔的中心间距为20μm至80μm，每个所述背表面上相邻两个所述背表面场接触孔的中心间距为20μm至80μm；
    可选地，每个所述发射极区域和所述背表面场区域均沿第二预设方向延伸，所述第二预设方向与所述第一预设方向垂直；在所述第二预设方向上，每个所述发射极上相邻两个所述发射极接触孔的中心间距为50μm至100μm，每个所述背表面上相邻两个所述背表面场接触孔的中心间距为20μm至80μm。
  4. 根据权利要求3所述的太阳能电池，其特征在于，所述发射极和所述背表面场相互交错设置，使得所述发射极接触孔和所述背表面场接触孔相互交错设置。
  5. 根据权利要求3或4所述的太阳能电池，其特征在于，在每个发射极区域，所述发射极接触孔设置为至少一列，其中，每列发射极接触孔中的多个发射极接触孔沿第二预设方向间隔分布，多列发射极接触孔沿第一预设方向间隔分布；在每个背表面场区域，所述背表面场接触孔设置为至少一列，其中，每列背表面场接触孔中的多个背表面场接触孔沿 第二预设方向间隔分布，多列背表面场接触孔沿第一预设方向间隔分布。
  6. 根据权利要求1至5中任一项所述的太阳能电池，其特征在于，所述隧穿氧化层为二氧化硅薄膜，且厚度为1至5nm；可选地，所述隧穿氧化层的厚度为1nm至3nm；
    和/或，所述多晶硅层的厚度为100nm至500nm。
  7. 根据权利要求1至6中任一项所述的太阳能电池，其特征在于，还包括：
    氮化硅减反层，形成于所述基底的正面的减反绒面的表面；
    氧化铝钝化层，形成于所述发射极和背表面场的表面；以及
    氮化硅钝化层，形成于所述氧化铝钝化层的表面；
    所述正电极贯穿所述氮化硅钝化层和所述氧化铝钝化层后与所述发射极电性连接，所述负电极贯穿所述氮化硅钝化层和所述氧化铝钝化层后与所述发射极电性连接；
    可选地，所述氮化硅减反层的厚度为80nm至120nm；
    可选地，所述氧化铝钝化层的厚度为3nm至20nm；
    可选地，所述氮化硅钝化层的厚度为75nm至150nm。
  8. 根据权利要求7所述的太阳能电池，其特征在于，在所述减反绒面的表面还通过浅磷扩散形成有前表面场，所述前表面场位于所述减反绒面和所述氮化硅减反层之间。
  9. 根据权利要求1至8中任一项所述的太阳能电池，其特征在于，还包括间隔分布的正极汇流条和负极汇流条；
    所述正极汇流条与每个所述正电极均电性连接，所述负极汇流条与每个所述负电极均电性连接；所述正极汇流条与所述负电极之间以及所述负极汇流条与所述正电极之间均间隔有绝缘胶。
  10. 根据权利要求9所述的太阳能电池，其特征在于，所述正电极和所述负电极均沿第三预设方向延伸，所述正极汇流条和所述负极汇流条的延伸方向垂直于所述正电极的延伸方向，所述负极汇流条的延伸方向垂直于所述负电极的延伸方向。
  11. 一种太阳能电池的制备方法，其特征在于，包括：
    对基底进行硼扩散，在所述基底的表面形成硼扩散层及位于所述硼扩散层表面的硼硅玻璃；
    将所述基底的第一表面作为所述基底的背面，在所述基底的背面的所述硼硅玻璃的局部区域依次进行激光开槽以及所述硼扩散层刻蚀，形成背表面场区域；未开槽和刻蚀的区域为发射极区域，所述发射极区域和所述背表面场区域被配置为在所述基底的背面交替分布；
    在所述基底的背面生长隧穿氧化层然后沉积本征非晶硅层；
    对所述基底进行磷扩散，以使所述本征非晶硅层形成材质为掺磷多晶硅的多晶硅层， 并在所述多晶硅层表面生成磷硅玻璃；
    在所述背表面场区域对应的所述磷硅玻璃表面印刷耐腐蚀浆料，并烘干所述耐腐蚀浆料；所述耐腐蚀浆料溶于碱且不溶于酸；
    用酸去除所述发射极区域对应的所述磷硅玻璃；
    用碱去除所述耐腐蚀浆料以及与所述发射极区域对应的所述多晶硅层和所述隧穿氧化层；
    用酸去除所述基底的背面剩余的所述磷硅玻璃和所述硼硅玻璃；
    所述发射极区域剩余的所述硼扩散层作为发射极；所述背表面场区域剩余的所述隧穿氧化层和所述多晶硅层作为背表面场；
    将正电极与所述发射极电性连接并将负电极与所述背表面场电性连接。
  12. 根据权利要求11所述的制备方法，其特征在于，所述用碱去除所述耐腐蚀浆料以及与所述发射极区域对应的所述多晶硅层和所述隧穿氧化层的步骤包括：
    先用第一碱液去除所述耐腐蚀浆料，然后用第二碱液去除所述发射极区域对应的所述多晶硅层和所述隧穿氧化层；
    其中，所述第一碱液的碱性小于所述第二碱液的碱性。
  13. 根据权利要求11或12所述的制备方法，其特征在于，所述将正电极与所述发射极电性连接并将负电极与所述背表面场电性连接的步骤包括：
    在所述发射极开设发射极接触孔，在与所述发射极接触孔对应的区域印刷所述正电极；
    在所述背表面场开设背表面场接触孔，在与所述表面场接触孔对应的区域印刷所述负电极。
  14. 根据权利要求11至13中任一项所述的制备方法，其特征在于，将所述基底的第二表面作为所述基底的正面，在所述基底的表面形成减反绒面的步骤包括：
    在所述用碱去除所述耐腐蚀浆料以及与所述发射极区域对应的所述多晶硅层和所述隧穿氧化层的步骤之后，且在所述用酸去除所述基底的背面剩余的所述磷硅玻璃和所述硼硅玻璃的步骤之前，用酸去除所述基底的正面的所述磷硅玻璃和所述硼硅玻璃，然后对所述基底的正面进行制绒处理形成所述减反绒面。
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