TWI495127B - 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 battery, a manufacturing method thereof and a module thereof, in particular to a crystal solar cell, a manufacturing method thereof and a module thereof.

Generally, a solar cell generally includes: a substrate that converts light energy into electrical energy, an anti-reflection layer disposed on a front surface of the substrate, and an electrode disposed on the substrate and capable of transmitting the electrical energy of the substrate outward. unit. In the fabrication of the solar cell, the substrate is first roughened to have a roughened structure on the front side of the substrate, and then the anti-reflection layer is disposed on the front surface, and finally on the reflective layer and the substrate. The electrode unit is disposed on one of the back sides.

Generally, the design having the roughened structure on the front surface and the anti-reflection layer on the front surface is for increasing the incident amount of light emitted from the outside to the substrate, thereby increasing the utilization of light and increasing the Photoelectric conversion efficiency of solar cells. In addition, there are also a plurality of linear structures spaced apart from each other on the front surface of the substrate, and the incident amount of light incident from the outside into the substrate is increased by the linear structure.

However, since the solar cell is usually made of a crystal substrate, it has better absorption for short-wavelength light and poor absorption for medium- and long-wavelength light. Therefore, after light is incident on the substrate through the front surface, the substrate absorbs short-wavelength light to be converted into electrical energy. In addition, since the medium-long wavelength light is emitted from the outside to the front surface, the reflection phenomenon is likely to occur, so that only a small portion of the medium-long wavelength light can be incident into the substrate.

Therefore, if the reflection phenomenon of medium-long wavelength light entering the substrate is reduced, and the reflection, refraction path and scattering effect of the medium-long wavelength light in the substrate are increased, thereby increasing the chance of the substrate absorbing medium- and long-wavelength light, Will increase the photoelectric conversion efficiency of solar cells.

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 increase light absorption efficiency and improve photoelectric conversion efficiency.

Thus, the solar cell of the present invention comprises a substrate, and an emitter layer and an electrode unit on the substrate.

The substrate includes a light-receiving front side and a back side opposite the front side. The front surface has a plurality of nanowires extending along a first direction and spaced apart from each other, and a plurality of first recesses and a plurality of second recesses respectively spacing the plurality of nanowires, the plurality of nanometers At least one of the rice lines is located between one of the first grooves and one of the second grooves.

The depth of the plurality of first grooves in the first direction is greater than the depth of the plurality of second grooves in the first direction, and the plurality of first grooves and the plurality of second grooves are at the The depth difference in one direction is greater than 700 nm, The distance between the two adjacent first grooves in a second direction perpendicular to the first direction is greater than 700 nm, and at least one of the plurality of second grooves is located between any two adjacent first grooves.

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 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 comprising a light-receiving front surface and a back surface opposite to the front surface; etching the front surface using an etching solution, the etching solution comprising a etchant, the first metal An ion source and a second metal ion source, wherein the first metal ion source and the second metal ion source are different metal ion sources, the etching solution forming the front surface to form a plurality of first ones extending along a first direction a groove and a plurality of second grooves, and the front surface forms a plurality of nanowires extending in the first direction and spaced apart by the plurality of first grooves and the plurality of second grooves, the number At least one of the plurality of nanowires is located between one of the first grooves and one of the second grooves, and the depth of the plurality of first grooves in the first direction is greater than the plurality of second grooves a depth difference in the first direction, a depth difference between the plurality of first grooves and the plurality of second grooves in the first direction is greater than 700 nm, and any two adjacent first grooves are perpendicular to the first The distance in the second direction of the direction is greater than 700 nm, and the plurality At least one of the second grooves is located between any two adjacent first grooves; forming an emitter layer on the substrate; An electrode unit is formed on the substrate.

The invention has the effect that the front surface forms the plurality of first grooves having the depth difference and the plurality of second grooves, and the plurality of nanowires which are spaced apart, the foregoing innovative structural design The ratio of the medium-long wavelength light refracting into the substrate can be increased, and the reflection path and the scattering effect of the medium-long wavelength light in the substrate can be increased, thereby improving the light absorption efficiency and improving the photoelectric conversion efficiency.

11‧‧‧ first plate

12‧‧‧Second plate

13‧‧‧Solar battery

14‧‧‧Package

15‧‧‧welding wire

2, 2'‧‧‧ substrate

21, 21’ ‧ ‧ positive

211, 211'‧‧‧ nano line

212, 212'‧‧‧ first groove

213‧‧‧second groove

214, 214’‧‧‧ bottom

215, 215’ ‧ ‧ imaginary surface

22‧‧‧ Back

23‧‧ ‧ emitter layer

24‧‧‧Anti-reflective layer

3‧‧‧Electrode unit

31‧‧‧ positive electrode

32‧‧‧Back electrode

81‧‧‧First direction

82‧‧‧second direction

91~94‧‧‧Steps

D1, d2‧‧ depth

D3‧‧‧ depth difference

D4‧‧‧distance

D5‧‧‧ length

Other features and advantages of the present invention will be apparent from the embodiments of the present invention, wherein: FIG. 1 is a partial cross-sectional view of a preferred embodiment of the solar cell module of the present invention; 1 is a schematic cross-sectional view of a solar cell; FIG. 3 is a partial enlarged view of FIG. 2; FIG. 4 is a block flow diagram of a preferred embodiment of the solar cell manufacturing method; A schematic flow chart of one step of the method; FIG. 6 is a schematic flow chart of the steps of the previous step of another embodiment of the manufacturing method; FIG. 7 is a photograph taken by a scanning electron microscope (SEM) in a comparative example; The embodiment of the present invention uses a photograph taken by a scanning electron microscope; and FIG. 9 is a relationship between light reflectance and wavelength of light, illustrating a comparative example and a real example. The reflectivity of the light for different wavelengths.

Referring to FIG. 1 , a preferred embodiment of the solar cell module of the present invention comprises: a first plate 11 and a second plate 12 disposed at an upper and lower interval, and a plurality of arrays arranged on the first plate 11 and the first A solar cell 13 between the two sheets 12, and a package 14 between the first sheet 11 and the second sheet 12 and coveringly contacting the plurality of solar cells 13. Of course, in practice, the solar cell module may include only one solar cell 13.

In this embodiment, the second plate 12 is also referred to as a back sheet, and the first plate 11 is located on the side where the light is incident, and may be made of a light transmissive material, such as a sheet of glass or plastic. No special restrictions are required. The plurality of solar cells 13 are electrically connected to each other through a plurality of ribbon wires 15. 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.

Referring to FIGS. 2 and 3, the solar cell 13 of the present embodiment includes a substrate 2, and an emitter layer 23 and an electrode unit 3 on the substrate 2.

The substrate 2 of the present embodiment may be a p-type or n-type crystal germanium substrate, and may be a single crystal germanium substrate or a polycrystalline germanium substrate. The substrate 2 includes a light-receiving front surface 21 and a back surface 22 opposite the front surface 21.

The front surface 21 has a plurality of nanowires 211 extending along a first direction 81 and spaced apart from each other, and a plurality of first recesses 212 and a plurality of second recesses respectively spacing the plurality of nanowires 211 213. At least one of the plurality of nanowires 211 is located between one of the first recesses 212 and one of the second recesses 213, and at least one of the plurality of second recesses 213 is located at any two adjacent Between the grooves 212. The depth d1 of the plurality of first grooves 212 in the first direction 81 is greater than the depth d2 of the plurality of second grooves 213 in the first direction 81. Each of the nanowires 211 has a bottom end 214 adjacent the back surface 22, and the bottom ends 214 of the plurality of nanowires 211 define an imaginary surface 215 that is undulating. Moreover, in practice, the first direction 81 of the present invention is substantially perpendicular to the direction of the front side 21 of the substrate 2.

In this embodiment, the depth d1 of the plurality of first grooves 212 is 800 to 5500 nm, and the depth d2 of the plurality of second grooves 213 is 100 to 4800 nm. The depth difference d3 of the plurality of first grooves 212 and the plurality of second grooves 213 in the first direction 81 is greater than 700 nm, but less than 5400 nm. The distance d4 of any two adjacent first grooves 212 in a second direction 82 perpendicular to the first direction 81 is greater than 700 nm, but less than 5400 nm. The length d5 of the plurality of nanowires 211 in the second direction 82 is 20 to 300 nm. The effect that can be achieved by the innovative structural design of the front side 21 of the substrate 21 of the present embodiment, and the meaning of the aforementioned numerical definition, Bright.

The emitter layer 23 of the embodiment is disposed in the front surface 21, and one of the substrate 2 and the emitter layer 23 is an n-type semiconductor, and the other is a p-type semiconductor, thereby forming a pn junction, which is a photovoltaic The source of special effects. An anti-reflection layer 24, such as tantalum nitride (SiN _x ), may be disposed on the emitter layer 23 to reduce light reflection to increase the amount of light incident and reduce the surface recombination velocity of the carrier (Surface Recombination Velocity) , referred to as SRV). Since the improvement of the present invention is not here, it will not be described in detail.

The electrode unit 3 of the embodiment is located on the substrate 2 and includes a positive electrode 31 on the anti-reflection layer 24 and passing through the anti-reflection layer 24 to contact the emitter layer 23, and one on the back surface 22. Back electrode 32. The positive electrode 31 and the back electrode 32 cooperate to output the electrical energy generated by the solar cell 13. However, since the positive electrode 31 and the back electrode 32 are not the improvement points of the present invention, they are not described herein, and the specific structure is not limited thereto. An example of this embodiment.

It should be noted that if the solar cell 13 is in the form of an Interdigitated Back Contact (IBC) solar cell, the emitter layer 23 is disposed in the back surface 22, and the electrode unit 3 includes only the back electrode 32 on the back surface 22, and thus the position where the electrode unit 3 and the emitter layer 23 are disposed, and the detailed structure of the solar cell 13 are not limited to the form disclosed in the embodiment.

Referring to Figures 3, 4 and 5, a preferred embodiment of the method of fabricating the solar cell 13 of the present invention comprises:

(1) Step 91: The substrate 2 is provided.

(2) Step 92: etching the front surface 21 of the substrate 2 using an etching solution (not shown), such that the front surface 21 forms the plurality of first recesses 212, the plurality of second recesses 213, and the plurality of Nano line 211.

Specifically, in this embodiment, the substrate 2 is immersed in the etching solution for 10 minutes in a room temperature environment, wherein the etching solution comprises an etchant, a first metal ion source and a second metal ion source. And the first metal ion source and the second metal ion source are different metal ion sources, so the ability of the two to catalyze etching is different.

In this embodiment, the etching action of the etchant is combined with the catalysis of the first metal ion source, so that the front surface 21 is etched to form the plurality of first recesses 212; similarly, the etching action of the etchant is matched. The catalysis of the second metal ion source causes the front surface 21 to be etched to form the plurality of second recesses 213. Thus, the plurality of first grooves 212 and the plurality of second grooves 213 are respectively formed on the front surface 21 in a recessed manner along the first direction 81, and collectively separate the front surface 21 and extend along the first direction 81. And the plurality of nanowires 211 spaced apart from each other.

In practice, the etchant may be hydrofluoric acid (HF) or hydrogen peroxide (H ₂ O ₂ ), and in this embodiment, hydrofluoric acid is specifically used. The first metal ion source is gold (Au), silver (Ag), copper (Cu), iron (Fe), titanium (Ti), platinum (Pt), palladium (Pd), nickel (Ni), zinc ( A compound of Zn), tin (Sn) or chromium (Cr), and in this embodiment specifically, copper nitrate (Cu(NO ₃ ) ₂ ) is used. The second metal ion source is a compound of gold, silver, copper, iron, titanium, platinum, palladium, nickel, zinc, tin or chromium, and in this embodiment, silver nitrate (AgNO ₃ ) is specifically used. In addition, the volume ratio of the etchant, the first metal ion source and the second metal ion source of the etching solution of the present embodiment is 23:1:1.

It is further explained that as long as two or more different metal ion sources are mixed in the etching solution, the front surface 21 can be formed into grooves having different depths in one etching process, and the grooves of different depths mentioned above can be used. The nanowires are spaced apart, so the etching method in step 92 is not limited to the embodiment disclosed in the embodiment.

Further, in practice, step 92 can also be performed in a two-etching operation as shown in FIG. That is, a first recess 212 having a deep depth d1 is formed on the front surface 21 by using an etching solution containing only one metal ion source and having a relatively high concentration of the foregoing metal ion source, and then the cleaning or cleaning may be performed as needed. Front 21. Then, using the etching solution having the same metal ion source as that described above but having a lower concentration, a plurality of second recesses 213 having a shallower depth d2 are formed on the front surface 21, so that the plurality of first recesses 212 can also be transmitted through the plurality of first recesses 212. Together with the plurality of second grooves 213, the front surface 21 is separated from the plurality of nanowires 211. Certainly, the order in which the plurality of first grooves 212 and the plurality of second grooves 213 are formed may be reversed, and is not limited to the foregoing examples.

It should be noted that, in implementation, in the process of forming the plurality of first grooves 212 and the plurality of second grooves 213, related parameters such as concentration and temperature of the etching solution, etching time, etc. may be Different adjustments are needed, so there is no need to limit them here.

Referring again to FIGS. 3, 4, and 5, (3) step 93: forming the emitter layer 23 on the substrate 2.

Specifically, in the present embodiment, the emitter layer 23 is formed on the inner side of the front surface 21 of the substrate 2 by a diffusion process, so that the emitter layer 23 forms a p-n junction with the substrate 2. Further, in the implementation, the anti-reflection layer 24 may be formed on the front surface 21 by a vacuum coating method such as physical vapor deposition (PVD) or chemical vapor deposition (CVD).

It should be noted that the diffusion depth of the embodiment is greater than the length of the plurality of nanowires 211 in the first direction 81. Therefore, the emitter layer 23 has portions formed within the plurality of nanowires 211 at the same time. And a portion extending from the bottom end 214 of the plurality of nanowires 211 toward the inside of the substrate 2. However, in practice, the diffusion depth can be adjusted according to requirements, especially when the diffusion depth is equal to or smaller than the length of the plurality of nanowires 211, the emitter layer 23 has only formed on the plurality of nanowires 211. Inside part. Therefore, the structure of the emitter layer 23 is not limited to the form disclosed in the embodiment.

(4) Step 94: The electrode unit 3 is formed on the substrate 2.

Specifically, the positive electrode 31 of the electrode unit 3 may be disposed on the anti-reflective layer 24 by using a screen printing, a jet printing or a vacuum coating method, and the back electrode 32 of the electrode unit 3 may be disposed on the back surface 22, wherein The positive electrode 31 passes through the anti-reflection layer 24 to contact the emitter layer 23. Since the detailed manufacturing process of the electrode unit 3 is not the focus of the present invention, the description of the manner in which the electrode unit 3 is disposed and the position on the substrate 2 are not limited to the examples of the embodiment.

Referring to Figures 3, 7, 8, and 9, the efficacy of the present invention is demonstrated by comparative examples and examples of the present invention. Among them, the comparative example first uses only An etching solution of a metal ion source etches the front side 21' of the substrate 2', and then proceeds to step 93, step 94. In the embodiment, in step 92, the front side 21 of the substrate 2 is etched using an etching solution containing two different metal ion sources, and then step 93 and step 94 are performed.

Fig. 7 is a photograph taken by a scanning electron microscope (SEM) after etching the front surface 21' of the substrate 2' with an etching solution containing only one metal ion source. Figure 8 is a photograph taken immediately after the step 92 of the embodiment using a scanning electron microscope. 9 is a graph showing the relationship between the light reflectance and the wavelength of light in the comparative example and the embodiment, wherein the light reflectance is measured on the front side of the solar cell 13.

As can be seen from FIG. 7, since the comparative example etches the front surface 21' of the substrate 2' using an etching solution containing only one metal ion source, the plurality of first recesses 212' and the plurality of nai are formed only on the front surface 21'. The rice line 211', then the imaginary surface 215' defined by the bottom end 214 of the plurality of nanowires 211' is relatively flat. As can be seen from FIG. 8, in step 92, the front surface 21 of the substrate 2 is etched using an etching solution containing two different metal ion sources, and the first front concaves having the depth difference d3 from each other are formed on the front surface 21. The slot 212 and the plurality of second recesses 213, and the plurality of nanowires 211 separated by the plurality of first recesses 212 and the plurality of second recesses 213, and then the plurality of nanowires The imaginary surface 215 defined by the bottom end 214 of the 211 is undulating.

As can be seen from Fig. 9, the reflectance of the comparative example is about 10% on average, and in the range of the wavelength of light of 400 to 1000 nm, the reflectance of the comparative example is low for short-wavelength light, and the reflectance thereof also increases with the increase of the wavelength of light. Increase. This is because the substrate 2' of the comparative example is made of a wafer substrate, which is excellent in absorbability for short-wavelength light and poor in absorbability for medium- and long-wavelength light, and thus cannot effectively utilize medium- and long-wavelength light.

On the other hand, the reflectance of the embodiment of the present invention is on average about 2%, and is substantially lower than the average value of the reflectance of the comparative example. In the range of light wavelengths of 400 to 1000 nm, the reflectance of the embodiment of the present invention is low regardless of medium or long wavelength light or short wavelength light, and the reflectance of the embodiment of the present invention varies with the wavelength of light. The magnitude is small. This is because the first roughening structure formed by arranging the plurality of nanowires 211 at intervals can increase the scattering effect of the light and increase the path of reflection and refraction of the light, thereby increasing the chance of the substrate 2 absorbing the light. Further, the second roughening structure formed by the imaginary surface 215 of the undulations can increase the proportion of the medium-long wavelength light refracted into the substrate 2, and increase the reflection path of the medium-long wavelength light in the substrate 2. With the scattering effect, the light absorption efficiency can be further improved and the photoelectric conversion efficiency can be improved.

In order to achieve the anti-reflection effect of the first roughening structure, the depth d1 of the plurality of first grooves 212 is 800-5500 nm, and the depth d2 of the plurality of second grooves 213 is 100-4800 nm. The length d5 of the rice noodle 211 in the second direction 82 is 20 to 300 nm. If the depth d1 and the depth d2 are too shallow, the lengths of the plurality of nanowires 211 spaced apart from the plurality of second grooves 213 in the first direction 81 are Insufficient, resulting in insufficient roughness of the first roughened structure described above to reduce the anti-reflection effect. If the depth d1 and the depth d2 are too deep, the length of the plurality of nanowires 211 in the first direction 81 will be too long. The structural strength is lowered, and it is easy to collapse and damage, and cannot be used. In other words, when the plurality of nanowires 211 are too long, part of the nanowires 211 may collapse due to surface Coulomb force. , causing the anti-reflection ability of the aforementioned first roughened structure to decrease. Further, when the length d5 is less than 20 nm, the plurality of nanowires 211 are too fine to lower the structural strength, and are also easily collapsed and damaged and cannot be used. If the length d5 is greater than 300 nm, the roughness of the first roughened structure described above is lowered, thereby reducing the antireflection effect.

On the other hand, in order to achieve the anti-reflection effect of the second roughening structure on the medium-long wavelength light, the depth difference d3 between the plurality of first grooves 212 and the plurality of second grooves 213 is greater than 700 nm, but less than 5400 nm. . The distance d4 of any two adjacent first grooves 212 is greater than 700 nm, but less than 5400 nm. Wherein, if the depth difference d3 is below 700 nm or the distance d4 is above 5400 nm, the imaginary surface 215 defined by the bottom end 214 of the plurality of nanowires 211 is relatively insufficient in degree of undulations, resulting in the second roughening. The roughness of the structure is insufficient to reduce the anti-reflection effect.

It is further explained that the depth difference d3 and the distance d4 can be adjusted according to the optical band to be improved, and the range of the depth difference d3 and the distance d4 can effectively reduce the reflectance of the medium and long wavelength light, and can be improved. The ratio of the medium-long wavelength light refracting into the substrate 2 and the scattering effect increase the path of the medium-long wavelength light conduction in the substrate 2, thereby improving the light absorption efficiency and the photoelectric conversion efficiency.

It should be noted that the first roughening structure and the second roughening structure are mainly used for the light receiving surface of the solar cell 13. Since the solar cell 13 exemplified in the present invention is in the form of single-sided light receiving, the foregoing The first roughening structure and the second roughening structure are disposed on the front surface 21 of the solar cell 13. Of course, in practice, the solar cell 13 can also be in the form of double-sided light receiving. In this case, the foregoing structure can be used for the front and back surfaces of the double-sided light receiving type solar cell.

In summary, the present invention forms the plurality of first grooves 212 and the plurality of second grooves 213 having the depth difference d3 from each other, and the plurality of nanowires 211 spaced apart from each other. The foregoing innovative structural design can increase the path of light reflection, refraction, and scattering through the first roughening structure formed by the plurality of nanowires 211, thereby enhancing the chance of the substrate 2 absorbing the light. In addition, the second roughening structure formed by the imaginary surface 215 defined by the bottom end 214 of the plurality of nanowires 211 has obvious anti-reflection effect on medium and long-wavelength light, and can increase the refraction of the medium-long wavelength light into the The ratio in the substrate 2 increases the reflection path and scattering effect of the medium-long wavelength light in the substrate 2, thereby further increasing the light absorption efficiency and improving the photoelectric conversion efficiency.

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

21‧‧‧ positive

211‧‧‧Nami line

212‧‧‧First groove

213‧‧‧second groove

214‧‧‧ bottom

215‧‧‧ imaginary surface

23‧‧ ‧ emitter layer

24‧‧‧Anti-reflective layer

3‧‧‧Electrode unit

31‧‧‧ positive electrode

81‧‧‧First direction

82‧‧‧second direction

D1, d2‧‧ depth

D3‧‧‧ depth difference

D4‧‧‧distance

D5‧‧‧ length

Claims (9)

A solar cell comprising: a substrate comprising a light-receiving front surface, and a back surface opposite to the front surface, the front surface having a plurality of nanowires extending along a first direction and spaced apart from each other, and the plurality of nanometers respectively a plurality of first grooves and a plurality of second grooves spaced apart by the rice noodles, at least one of the plurality of nanowires being located between one of the first grooves and one of the second grooves, and the number The depth of the first groove in the first direction is greater than the depth of the plurality of second grooves in the first direction, and the plurality of first grooves and the plurality of second grooves are on the first side The upward depth difference is greater than 700 nm and less than 5400 nm, and the distance between any two adjacent first grooves in a second direction perpendicular to the first direction is greater than 700 nm and less than 5400 nm, and at least one of the plurality of second grooves One is located between any two adjacent first grooves; an emitter layer is located on the substrate; and an electrode unit is located on the substrate. The solar cell of claim 1, wherein the plurality of nanowires have a length in the second direction of 20 to 300 nm. The solar cell of claim 1, wherein the plurality of first grooves have a depth in the first direction of 800 to 5500 nm. The solar cell of claim 1, wherein the plurality of second grooves have a depth in the first direction of 100 to 4800 nm. A solar cell module comprising: a first plate; a second sheet; at least one solar cell according to any one of claims 1 to 4, disposed between the first sheet and the second sheet; and a package material located at the first sheet and the second sheet Between the plates, and contact the solar cell. A method of manufacturing a solar cell, comprising: providing a substrate comprising a light-receiving front surface and a back surface opposite to the front surface; etching the front surface using an etching solution, the etching solution comprising a etchant, the first metal ion a source and a second metal ion source, wherein the first metal ion source and the second metal ion source are different metal ion sources, the etching solution forming the front surface to form a plurality of first recesses extending in a first direction a groove and a plurality of second grooves, and the front surface is formed with a plurality of nanowires extending in the first direction and spaced apart by the plurality of first grooves and the plurality of second grooves, the plurality of At least one of the nanowires is located between one of the first grooves and one of the second grooves, and the depth of the plurality of first grooves in the first direction is greater than the plurality of second grooves a depth in the first direction, a depth difference between the plurality of first grooves and the plurality of second grooves in the first direction is greater than 700 nm and less than 5400 nm, and any two adjacent first grooves are perpendicular to the first groove The distance in the second direction of the first direction is greater than 700 nm and Less than 5400 nm, and at least one of the plurality of second grooves is located between any two adjacent first grooves; forming an emitter layer on the substrate; An electrode unit is formed on the substrate. The method of manufacturing a solar cell according to claim 6, wherein the first metal ion source is a compound of gold, silver, copper, iron, titanium, platinum, palladium, nickel, zinc, tin or chromium, the first The source of the two metal ions is a compound of gold, silver, copper, iron, titanium, platinum, palladium, nickel, zinc, tin or chromium. The method of manufacturing a solar cell according to claim 6, wherein the etchant is hydrofluoric acid or hydrogen peroxide. The method of manufacturing a solar cell according to claim 6, wherein the etching solution, the first metal ion source and the second metal ion source have a volume molar ratio of 23:1:1.