TWI492401B - Solar cell, method of manufacturing the same and module comprising the same - Google Patents

Description

Solar cell, manufacturing method thereof and module thereof

The invention relates to a solar cell, a manufacturing method thereof and a module thereof, in particular to a back contact solar cell, a manufacturing method thereof and a module thereof.

Referring to Figures 1 and 2, there is a known Interdigitated Back Contact (IBC) solar cell comprising: an n-type substrate 91, a passivation layer 92, at least one p-type electrode 93, and at least An n-type electrode 94.

The substrate 91 includes a light receiving surface 911 and a back surface 912 opposite to each other, an n-type doping layer 913 on the side of the light receiving surface 911 and having a doping concentration greater than the substrate 91, and one on the n-type doping layer 913. An anti-reflective layer 914, at least one p-type doped region 915 on the back surface 912 side and at least one n-type doped region 916, and at least one separate the p-type doped region 915 from the n-type doped region 916 The concave structure 917. The passivation layer 92 is located on the back surface 912 of the substrate 91 and covers the p-type doping region 915, the n-type doping region 916 and the recess structure 917. The p-type electrode 93 is located on the passivation layer 92 and passes through the passivation layer 92 to connect the p-type doping region 915. The n-type electrode 94 is located on the passivation layer 92 and is connected through the passivation layer 92. The n-doped region 916 is connected.

It is further noted that the solar cell is provided with the recessed structure 917 in order to prevent the p-type doping region 915 from contacting the n-type doping region 916 to avoid parasitic shunting and generating leakage current (Leakage Current). ). In the fabrication, the p-doped region 915 and the n-doped region 916 can be respectively formed on the back surface 912 of the substrate 91 by a diffusion process, and the p-doped region 915 and the n-doped region are in this case. The boundaries of 916 are connected to each other, so it is usually necessary to perform the steps shown in FIG. 2: firstly, the concave structure is formed by laserly connecting the p-type doping region 915 and the n-type doping region 916. 917, the surface within the recessed structure 917 is then etched using a potassium hydroxide (KOH) solution to remove the laser damaged layer generated by the laser to the substrate 91. After completion, the passivation layer 92 is formed on the back surface 912, and the subsequent manufacturing process of the solar cell is continued, for example, the p-type electrode 93 and the n-type electrode 94 are provided.

However, in the foregoing manufacturing method, in addition to the high manufacturing cost due to the use of the laser opening, the method of laser opening is a one-way dry etching stripping method, followed by etching with a potassium hydroxide solution. When cleaning, the recessed structure 917 forms a first right angle structure 918 connecting the p-type doping region 915, and a second connecting the n-type doping region 916 due to its anisotropic etching action. Right angle structure 919.

The sharp topography of the first right angle structure 918 and the second right angle structure 919 causes the passivation layer 92 to have a problem of uneven step coverage, and even if the thickness of the passivation layer 92 is significantly uneven, In turn, it affects the passivation effect. Adding the passivation layer 92 to the first The thickness of the sharp-angled structure 918 is thinner, or even the amount of coating is insufficient. This further reduces the passivation quality of the passivation layer 92 on the back doped region of the substrate 91, thereby affecting the power of the solar cell. Sexual effect.

In addition, when the solar cell is in operation, it is easy to cause charge concentration and electric field concentration due to the sharp topography of the first right angle structure 918 and the second right angle structure 919, which will cause the solar cell to have excessive charge accumulation. The damage, and thus the service life of the solar cell, reduces the photoelectric conversion efficiency of the solar cell, so the structure of the known solar cell still needs to be improved.

Accordingly, it is an object of the present invention to provide a solar cell, a method of manufacturing the same, and a module thereof that can improve photoelectric conversion efficiency and service life.

Therefore, the solar cell of the present invention comprises: a first conductivity type substrate, a first conductivity type doping layer, a second conductivity type doping layer, a recess structure, a passivation layer, a first electrode, and a second electrode.

The substrate includes a light-receiving front side and a back side opposite the front side. The first conductive type doped layer is located on the back surface of the substrate, and the second conductive type doped layer is located on the back surface of the substrate and adjacent to the first conductive type doped layer. The concave structure is located between the first conductive type doped layer and the second conductive type doped layer, and the first conductive type doped layer and the second conductive type doped layer are adjacent to the concave structure and close to the A protruding arc angle is formed on the back side. The passivation layer is disposed on the back surface and contacts the first conductive type doped layer and the second conductive type doped layer. The first electrode is on the passivation layer and The first conductive type doped layer is contacted through the passivation layer. The second electrode is located on the passivation layer and passes through the passivation layer to contact the second conductive type doped layer.

The solar cell module of the present invention comprises: a first plate, a second plate, at least one solar cell disposed between the first plate and the second plate and as described above, and a first plate and the first plate A package material between the two plates and contacting the solar cell.

The method for manufacturing a solar cell of the present invention comprises: providing a substrate of a first conductivity type, the substrate comprising a light-receiving front surface, and a back surface opposite to the front surface; and forming a second conductive type doping layer on the back surface of the substrate Configuring a mask layer on the second conductive type doped layer; forming an opening on the mask layer, and removing a portion of the second conductive type doped layer corresponding to the opening; Forming a first conductive type doped layer on the back surface of the substrate, the first conductive type doped layer is adjacent to the second conductive type doped layer and has an interface between each other; removing the mask layer; An etching material covers the interface between the first conductive type doped layer and the second conductive type doped layer, and etches the interface through the etching material to form a concave structure, so that the first conductive type The doped layer and the second conductive type doped layer are adjacent to the concave structure and form a protruding arc angle near the back surface; at the back of the substrate and at the first conductive type doped layer and the second conductive Forming a passivation layer on the doped layer; forming a first electrode disposed on the passivation layer and contacting the passivation layer to contact the first conductive type doped layer; and forming a layer disposed on the passivation layer and passing through the passivation layer to contact the second conductive type The second electrode of the hybrid layer.

The invention has the advantages that the first conductive type doped layer and the second conductive type doped layer are improved in close proximity to the concave structure and close to the back surface, and the innovative design of the protruding arc angle can avoid the solar cell being The phenomenon of charge concentration and electric field concentration occurs during operation to overcome the problem that the solar cell is easily damaged due to excessive charge accumulation, thereby improving the service life of the solar cell, and also enabling the subsequent configuration of the passivation layer. The thickness of the portion protruding from the arc angle is uniform, and the quality and passivation effect of the passivation layer are improved, thereby improving the photoelectric conversion efficiency of the solar cell.

11‧‧‧ first plate

12‧‧‧Second plate

13‧‧‧Solar battery

14‧‧‧Package

2‧‧‧Substrate

201‧‧‧ positive

202‧‧‧Back

203‧‧‧ first face

204‧‧‧ second face

21‧‧‧First Conductive Doped Layer

211‧‧‧First connection

22‧‧‧Second Conductive Doped Layer

22'‧‧‧Second Conductive Doped Layer

221‧‧‧Second connection

23‧‧‧ concave structure

231‧‧‧ bottom

232‧‧‧ bottom part

24‧‧‧ Third Conductive Doped Layer

25‧‧‧Anti-reflective layer

26‧‧‧ junction

3‧‧‧ Passivation layer

31‧‧‧ first opening

32‧‧‧second opening

41‧‧‧First electrode

42‧‧‧second electrode

6‧‧‧welding wire

700‧‧‧ etching materials

800‧‧‧mask layer

801‧‧‧ openings

S01~S12‧‧‧Steps

Other features and effects of the present invention will be apparent from the following description of the drawings. FIG. 1 is a partial cross-sectional view of a known interdigitated back contact solar cell; FIG. 2 is a schematic view of FIG. A schematic diagram of an incomplete manufacturing process of a solar cell, illustrating a manufacturing process in which a p-type doped region of the solar cell is separated from an n-type doping region; FIG. 3 is a preferred embodiment of the solar cell module of the present invention. FIG. 4 is a partial cross-sectional view showing a solar cell of the preferred embodiment; FIG. 5 is a block diagram showing the steps of a preferred embodiment of the solar cell manufacturing method of the present invention; Fig. 6 is a schematic view showing the steps of the preceding step of the manufacturing method; and Fig. 7 is a schematic view showing the subsequent steps of the manufacturing method.

Referring to FIG. 3 and FIG. 4, a preferred embodiment of the solar cell module of the present invention comprises: a first plate 11 and a second plate 12 disposed opposite each other, and a plurality of arrays arranged on the first plate 11 and A solar cell 13 between the second plates 12 and electrically connected to each other, and a package 14 between the first plate 11 and the second plate 12 and coveringly contacting the solar cells 13. Of course, in practice, the solar cell module may include only one solar cell 13.

In this embodiment, the first plate 11 is also referred to as a back sheet, and the second plate 12 is located on the side where the light is incident, and may be made of a light-transmitting material, such as a glass or plastic material. Special restrictions are required. The plurality of solar cells 13 are electrically connected to each other through a plurality of ribbon wires 6. The material of the package material 14 is ethylene-vinyl acetate copolymer (EVA) or other related materials that can be used for solar cell module packaging, and is not limited to the examples of the embodiment.

Since the structure of the solar cell module is not an improvement of the present invention, it will not be described again, and is also simply illustrated in FIG. In addition, since the structures of the several solar cells 13 are the same, only one of them will be described below as an example. Of course, the structure of the plurality of solar cells 13 in a module is not absolutely necessary.

The solar cell 13 of the present embodiment is a back contact solar cell, and includes: a first conductivity type substrate 2, a first conductivity type doping layer 21, two second conductivity type doping layers 22, and two inner layers. The concave structure 23, a passivation layer 3, a first electrode 41, and two second electrodes 42. This embodiment The first conductivity type and the second conductivity type are respectively an n-type semiconductor and a p-type semiconductor, but may be reversed in implementation. The substrate 2 of the present embodiment is an n-type wafer substrate, and may be a single crystal germanium substrate or a polycrystalline germanium substrate. The substrate 2 includes a front surface 201 and a back surface 202 opposite to each other. The front surface 201 is a light receiving surface and faces the second plate material 12, and can be made into a rough surface as shown in FIG. 4 to increase the amount of light incident, but is not limited thereto. The back surface 202 faces the first plate 11 and has a pair of first faces 203 that should be doped with the first conductive type doping layer 21, and two second portions that respectively correspond to the two doped layers 22 of the second conductive type. Face 204. The first face 203 and the two second faces 204 usually have a height difference to avoid contamination during the subsequent diffusion process, but the implementation is not necessary in the foregoing structure, that is, the back face 202 can also be flat. The plane, that is, the height of the first surface 203 and the two second surface 204 at the same plane.

The first conductive type doped layer 21 of the present embodiment is disposed within the back surface 202. The first conductive type doped layer 21 is an n ⁺⁺ type semiconductor having a doping concentration greater than a doping concentration of the substrate 2. The second conductive type doped layer 22 of the present embodiment is a p-type semiconductor disposed in the back surface 202 and spaced apart from the first conductive type doped layer 21 at the first conductive type doped layer. The opposite side of 21.

It should be noted that, if the substrate 2 uses a p-type semiconductor substrate, the first conductive type doped layer 21 must be formed into a p ⁺⁺ type semiconductor having a doping concentration greater than that of the p-type substrate, and the two second The conductive doped layer 22 is fabricated as an n-type semiconductor.

The two concave structures 23 of this embodiment are respectively located at the first Between the conductive doped layer 21 and the two second conductive type doped layers 22, the first conductive type doped layer 21 and the two second conductive type doped layers 22 are in close proximity to the concave structure 23 and close to The back surface 202 defines a protruding arc angle, wherein the vicinity of the back surface 202 means that the first conductive type doped layer 21 is located near the first surface 203 of the back surface 202. The second conductive type doped layer 22 is located near the second face portion 204 of the back surface 202. Moreover, the so-called protruding arc angle of the present invention means that the first conductive type doped layer 21 and the two second conductive type doped layers 22 are connected to the corners of the concave structure 23, and their appearances are respectively formed. The outline of the outline is an arc-shaped smooth type, rather than the shape of a corner that directly turns.

Specifically, the first conductive type doping layer 21 has two first connecting portions 211 respectively connecting the two concave structures 23, and each of the second conductive type doping layers 22 has one connecting the two. The second connecting portion 221 of one of the concave structures 23, and each of the concave structures 23 has two bottom portions 231 between the first connecting portion 211 and the second connecting portion 221. Each of the first connecting portions 211, each of the second connecting portions 221 and each of the bottom portions 231 are curved, and each of the first connecting portions 211 and each of the second connecting portions 221 is as described above in the embodiment. The arc angle is highlighted, and each bottom 231 is an arc angle that is concave toward the inner arc.

In addition, when the two second faces 204 are used as a reference, a bottom surface portion 232 of each of the concave structures 23 between the two bottom portions 231 is away from the two second surface portions 204 than the first surface portion 203. .

In addition, a third conductive type doping layer 24 may be disposed within the front surface 201 of the substrate 2, which is an n ⁺ -type semiconductor having a doping concentration greater than that of the substrate 2, thereby forming a front electric field structure ( Front-Side Field (FSF) is used to improve carrier collection efficiency and photoelectric conversion efficiency. The third conductive type doping layer 24 may further be provided with an anti-reflection layer 25, such as tantalum nitride (SiN _x ), for increasing the incident light amount and reducing the surface recombination velocity (Surface Recombination Velocity, Referred to as SRV). However, in practice, the present invention is not necessary to provide the third conductive type doped layer 24 and the anti-reflective layer 25.

The passivation layer 3 of the present embodiment is disposed on the back surface 202 and is in contact with the first conductive type doped layer 21 and the two second conductive type doped layers 22. The material of the passivation layer 3 may be an oxide, a nitride or a combination of the above materials, specifically yttrium oxide (SiO _x ), and may be used for passivating and repairing the surface of the substrate 2, thereby reducing the surface suspension of the substrate 2. The Dangling Bond and the defect can reduce the carrier trap and reduce the surface recombination rate of the carrier to improve the conversion efficiency of the solar cell 13. The passivation layer 3 has a first opening 31 extending through the first surface 203 of the back surface 202, and a plurality of second openings 32 extending through the second surface 204 of the back surface 202, respectively.

The first electrode 41 of the present embodiment is disposed on the passivation layer 3 and contacts the first conductive type doped layer 21 through the first opening 31 of the passivation layer 3. The two second electrodes 42 of the present embodiment are respectively disposed on the passivation layer 3 and respectively pass through the plurality of second openings 32 to contact the corresponding second conductive type doping layer 22 .

It should be noted that, in this embodiment, a first conductive type doping layer 21, two second conductive type doping layers 22, and two concave structures 23 are used. For example, in fact, in a solar cell 13, the number of the second conductive type doping layer 22 and the first conductive type doping layer 21 may be more, and the pnpn is formed in a staggered configuration and repeatedly arranged. A concave structure 23 is formed between a group of adjacent second conductive type doped layers 22 and the first conductive type doped layer 21. Correspondingly, the first surface 203 of the back surface 202, the first opening 31 of the passivation layer 3, and the first electrode 41 correspond to the position and the number of the first conductive type doping layer 21, and the back surface 202 The second surface 204, the second opening 32 of the passivation layer 3, and the second electrode 42 all correspond to the position and number of the second conductive type doping layer 22. Furthermore, the present invention can also be modified only for one of the second conductive type doped layers 22, the first conductive type doped layer 21, and the concave structure 23.

Referring to Figures 4, 5, 6, and 7, a preferred embodiment of the method of fabricating a solar cell of the present invention comprises the following steps:

Step S01: The substrate 2 is provided, and the front surface 201 and the back surface 202 of the substrate 2 are polished.

Step S02: A second conductive type doped layer 22' is formed on the back surface 202 of the substrate 2. Specifically, a tri-group element (for example, boron, aluminum, gallium, indium, or antimony) may be doped at the back surface 202 by a diffusion process or other doping method, thereby forming a heavily doped p-type in the back surface 202. semiconductor.

Step S03: the second conductivity type doped layer 22 'disposed on a mask layer 800, the mask material layer 800, for example, silicon oxide (SiO _x). Specifically, the mask layer 800 may be formed by a vacuum coating method such as PECVD, wherein the vacuum coating method may include physical vapor deposition (PVD), chemical vapor deposition (CVD), or the like.

Step S04: forming an opening 801 on the mask layer 800, and removing a portion of the second conductive type doped layer 22' corresponding to the opening 801, thereby forming a mutual one on the back surface 202 of the substrate 2. The first face 203 and the two second faces 204 are different in height.

Specifically, in this step, the mask layer 800 is formed into the opening 801 by laser ablation, and then etched using a potassium hydroxide (KOH) solution to remove the second conductive type doped layer 22'. Corresponding to the portion at the opening 801, the two second conductive type doping layers 22 respectively located on opposite sides of the opening 801 are separated. At the same time, the portion of the back surface 202 corresponding to the opening 801 forms the first surface portion 203 recessed inwardly, and the portion of the back surface 202 corresponding to the two second conductive type doping layers 22 respectively form the two portions Two faces 204.

Step S05: forming the first conductive type doping layer 21 on the back surface 202 of the substrate 2 through the opening 801. Each of the second conductive type doping layers 22 is adjacent to the first conductive type doped layer 21 and has a mutual A junction of 26. Specifically, a fifth group element (for example, phosphorus or the like) may be doped at the back surface 202 by a diffusion process or other doping method, thereby forming a heavily doped n ⁺⁺ type of the first conductive layer in the back surface 202. Type doped layer 21.

Step S06: The mask layer 800 is removed.

Step S07: covering an interface 26 between the first conductive type doping layer 21 and the second conductive type doping layer 22 by an etching material 700, and etching the boundary portion 26 through the etching material 700 to form The concave structure 23 is such that the first conductive type doping layer 21 is doped with each second conductivity type The layer 22 is adjacent to the concave structure 23 and adjacent to the back surface 202 to form the protruding arc angles (that is, the first connecting portion 211 and the second connecting portion 221). In the present embodiment, the etching material 700 comprises phosphoric acid and ε-caprolactam.

Further, in this embodiment, the etching material 700 may be sprayed or coated on the back surface 202 by using inkjet printing (Inkjet Printing) or screen printing, and the etching material 700 may be covered thereon. The interface 26 between the first conductive type doped layer 21 and the second conductive type doped layer 22.

Then, a temperature of 300 to 550 ° C is provided to heat the etching material 700, and the etching material 700 is isotropically etched to the interface 26 to form the concave structure 23, and the first conductive type doping layer 21 is separately formed. a first connecting portion 211 connecting the two concave structures 23 and having an arc shape, and each of the second conductive type doping layers 22 respectively forming a second connecting portion 221 connecting the two concave structures 23 and having an arc shape . Each of the concave structures 23 forms two bottom portions 231 between the first connecting portion 211 and the second connecting portion 221 and is curved, and each of the two second surface portions 204 is used as a reference. The bottom surface portion 232 of the concave structure 23 between the two bottom portions 231 is away from the two second surface portions 204 than the first surface portion 203.

Wherein, when the temperature is lower than 300 ° C, the etching reaction efficiency of the etching material 700 is not good, so that the ideal concave structure 23 cannot be obtained, and when the temperature is higher than 550 ° C, the etching of the etching material 700 is also caused. The reaction efficiency is poor, which in turn leads to an underetching condition. Preferably, the aforementioned temperature is 350 to 400 °C. Finally, the substrate 2 is cleaned to remove the etching Material 700.

Step S08: forming the passivation layer 3 on the back surface 202 of the substrate 2 and on the first conductive type doping layer 21 and the two second conductive type doping layers 22. Specifically, the passivation layer 3 may be formed by a vacuum plating method such as PECVD, and the passivation layer 3 is formed in conformity with the topography of the back surface 202, that is, the passivation layer 3 corresponds to each of the second conductive type doping layers 22. The portion of the two connecting portions 221 is also curved in an outward arc convex shape.

Step S09: roughening the front surface 201 of the substrate 2, then forming the third conductive type doping layer 24 in the front surface 201, and forming the anti-resistance on the third conductive type doping layer 24. Reflective layer 25. Specifically, in the present embodiment, the front surface 201 is roughened by etching, so that the front surface 201 has an uneven structure to increase the amount of light incident. Then, doping is performed on the front surface 201 by using a diffusion process, and an n ⁺ -type semiconductor having a doping concentration greater than a doping concentration of the substrate 2 is formed in the front surface 201 to obtain the third conductive type doped layer 24 . . Finally, the continuous anti-reflection layer 25 is formed by a vacuum coating method such as PECVD. However, in practice, the manufacturing method is not necessary to include the step S09. In practice, step S09 can of course be performed before the formation of the first conductive type doped layer 21 and the two second conductive type doped layers 22.

Step S10: forming the first opening 31 corresponding to the first conductive type doping layer 21 on the passivation layer 3, and the plurality of second openings 32 respectively corresponding to the two second conductive type doping layers 22. Specifically, the first opening 31 and the plurality of second openings 32 may be formed on the passivation layer 3 by dry etching, such as laser etching, wet etching, or using an etchant.

Step S11: forming the first electrode 41 disposed on the passivation layer 3 and contacting the first conductive type doped layer 21 through the passivation layer 3. Specifically, the first electrode 41 is formed on the passivation layer 3 by using Screen Printing, Inkjet Printing or vacuum coating, and a part of the first electrode 41 is filled in the passivation layer 3 . The first opening 31 is in contact with the first conductive type doping layer 21 .

Step S12: forming the two second electrodes 42 disposed on the passivation layer 3 and passing through the passivation layer 3 to respectively contact the two second conductive type doping layers 22. In practice, the two second electrodes 42 may be formed on the passivation layer 3 in the same manner as in the step S11, so that a partial portion of the two second electrodes 42 is filled in the second opening 32 of the passivation layer 3. The two second conductive type doping layers 22 are respectively in contact with each other.

It should be noted that the present invention does not need to limit the order in which the first electrode 41 and the two second electrodes 42 are formed, and in fact, both can be simultaneously fabricated by one-time screen printing, printing or coating. Of course, if the first electrode 41 and the two second electrodes 42 are made of different materials, they can be separately fabricated.

As can be seen from the above description, in the step S07, the etching material 700 covers the interface 26 between the first conductive type doping layer 21 and the second conductive type doping layer 22, and is transparent. The etching material 700 etches the boundary portion 26 to form the recessed structure 23, and then the passivation layer 3 or the like is formed on the back surface 202 for subsequent processes. According to the above-described innovative manufacturing method, the steps of etching and opening a hole by a laser and a potassium hydroxide solution in the conventional solar cell manufacturing method can be omitted, thereby saving materials and reducing manufacturing costs. It also saves time and increases production efficiency. In addition, step S07 of the present invention does not use a laser device with a relatively high equipment cost to open the hole, but uses the etching material 700 which is inexpensive to open the hole, thereby greatly reducing the manufacturing cost.

It is worth mentioning that the present invention has an isotropic etching property through the etching material 700, and the first conductive type doping layer 21 and each of the second conductive type doping layers 22 are adjacent to the concave structure 23 and close to each other. The back surface 202 is modified to have a protruding arc angle (ie, the first connecting portion 211 and the second connecting portion 221), that is, the first connecting portion 211 of the first conductive type doping layer 21 is mixed with each second conductive type. The second connecting portions 221 of the hybrid layer 22 are all curved, which can avoid the phenomenon of charge concentration and electric field concentration during the operation of the solar cell 13 to overcome the problem that the solar cell is easily damaged due to excessive charge accumulation. The service life of the solar cell 13 of the present embodiment is improved.

In addition, through the design of the foregoing innovative structure and the innovative manufacturing method, the passivation layer 3 of the subsequent cladding can be made uniform for the thickness of each of the first connecting portions 211 and each of the second connecting portions 221, and the quality of the passivation layer 3 can be improved. With the passivation effect, thereby reducing the surface recombination rate of the carrier trap and the carrier, the photoelectric conversion efficiency of the solar cell 13 of the present embodiment can be further improved, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

13‧‧‧Solar battery

2‧‧‧Substrate

201‧‧‧ positive

202‧‧‧Back

203‧‧‧ first face

204‧‧‧ second face

21‧‧‧First Conductive Doped Layer

211‧‧‧First connection

22‧‧‧Second Conductive Doped Layer

221‧‧‧Second connection

23‧‧‧ concave structure

231‧‧‧ bottom

232‧‧‧ bottom part

24‧‧‧ Third Conductive Doped Layer

25‧‧‧Anti-reflective layer

3‧‧‧ Passivation layer

31‧‧‧ first opening

32‧‧‧second opening

41‧‧‧First electrode

42‧‧‧second electrode

Claims (10)

A solar cell comprising: a first conductivity type substrate comprising a light receiving front surface and a back surface opposite to the front surface; a first conductive type doped layer on the back side of the substrate; and a second conductive type doping a doped layer on the back side of the substrate and adjacent to the first conductive type doped layer; a concave structure between the first conductive type doped layer and the second conductive type doped layer, the first conductive The doped layer and the second doped layer are adjacent to the recessed structure and form a protruding arc angle adjacent to the back surface; a passivation layer is disposed on the back surface and contacts the first conductive type doped layer and a second conductive type doped layer; a first electrode on the passivation layer and passing through the passivation layer to contact the first conductive type doped layer; and a second electrode on the passivation layer and passing through The passivation layer contacts the second conductive type doped layer. The solar cell of claim 1, wherein the substrate is an n-type germanium substrate, the first conductive type doped layer is an n-type semiconductor, and a doping concentration of the first conductive type doped layer is greater than The doping concentration of the substrate, the second conductive type doped layer is a p-type semiconductor. The solar cell of claim 1, wherein the concave structure has two curved bottoms. A solar battery module comprising: a first plate; a second plate; at least one solar cell according to any one of claims 1 to 3, disposed between the first plate and the second plate; and a package material located at the first The sheet and the second sheet are in contact with the solar cell. A method for manufacturing a solar cell, comprising: providing a substrate of a first conductivity type, the substrate comprising a light receiving front surface, and a back surface opposite to the front surface; forming a second conductive type doping layer on the back surface of the substrate; Disposing a mask layer on the second conductive type doped layer; forming an opening on the mask layer, and removing a portion of the second conductive type doped layer corresponding to the opening; a first conductive type doped layer is formed on the back surface of the substrate, the first conductive type doped layer is adjacent to the second conductive type doped layer and has an interface between each other; the mask layer is removed; an etching is performed The material covers the interface between the first conductive type doped layer and the second conductive type doped layer, and etches the interface through the etching material to form a concave structure, so that the first conductive type is doped The impurity layer and the second conductive type doped layer form a protruding arc angle adjacent to the concave structure and adjacent to the back surface; on the back surface of the substrate, the first conductive type doped layer and the second conductive type Forming a passivation layer on the doped layer; Forming a first electrode disposed on the passivation layer and contacting the first conductive type doped layer through the passivation layer; and forming a layer disposed on the passivation layer and passing through the passivation layer to contact the second conductive layer A second electrode of the doped layer. The method of manufacturing a solar cell according to claim 5, wherein a temperature of 300 to 550 ° C is provided to heat the etching material to etch the interface to form the concave structure. The method of manufacturing a solar cell according to claim 5, wherein a temperature of 350 to 400 ° C is provided to heat the etching material to etch the interface to form the concave structure. The method of manufacturing a solar cell according to claim 5, wherein the material of the passivation layer contains ruthenium oxide. The method of manufacturing a solar cell according to claim 5, wherein the substrate is an n-type germanium substrate, the first conductive type doped layer is an n-type semiconductor, and the first conductive type doped layer is doped. The concentration is greater than the doping concentration of the substrate, and the second conductive type doped layer is a p-type semiconductor. The method of manufacturing a solar cell according to claim 5, wherein the etching material comprises phosphoric acid and caprolactam.