Disclosure of Invention
In view of this, in order to overcome the defects in the prior art, the utility model aims at providing an improved battery piece structure has reduced the shading area of the positive and back grid line of traditional battery piece, and has reduced the string of carrier transmission and hinder, improves solar cell's conversion efficiency.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a battery piece structure, includes front main grid line, front TCO conducting layer, front passivation antireflection layer, doping layer, crystal silicon substrate, back passivation layer, back TCO conducting layer and back main grid line from top to bottom in proper order, gomphosis each other between front TCO conducting layer and the front passivation antireflection layer, gomphosis each other between back TCO conducting layer and the back passivation layer. The front main grid line is only contacted with the front TCO conductive layer and is not contacted with the front passivation antireflection layer, the doping layer or the crystalline silicon substrate, and the back main grid line is only contacted with the back TCO conductive layer and is not contacted with the back passivation layer or the crystalline silicon substrate.
The embedding in this application is for seting up the laser groove on positive passivation antireflection layer or the back passivation layer (can be for the position that corresponds traditional vice grid line), later redeposit the TCO conducting layer again, make TCO conducting layer and positive passivation antireflection layer or the mutual gomphosis of back passivation layer, and set up the laser groove and make TCO conducting layer and doping layer or crystal silicon substrate direct contact, collect the transmission carrier through transparent conductive film material (TCO conducting layer), replace conventional vice grid line, can significantly reduce the shading area of positive and back grid line, thereby greatly increase the utilization ratio of light, reduce the series resistance of carrier transmission, be favorable to improving solar cell's conversion efficiency.
According to some preferred embodiments of the present invention, the front passivation anti-reflection layer has a front laser groove opened by laser, and the front TCO conductive layer is filled in the front laser groove and covered on the front passivation anti-reflection layer; the back passivation layer is provided with a back laser groove formed by laser, and the back TCO conductive layer is filled in the back laser groove and covers the back passivation layer. The laser parameters of the laser (532nm-556nm, green) grooving are as follows: the laser power is 12w-30w, and the laser frequency is 900 KHz. The widths of the front laser groove and the back laser groove obtained by laser grooving are 10-120 um; the depth is 0.5-2 um.
According to some preferred embodiments of the present invention, each of the front laser grooves and/or the back laser grooves is formed continuously or intermittently. The front laser groove and/or the back laser groove are arranged corresponding to the positions of the secondary grid lines in the traditional battery piece, and the distance between the adjacent laser grooves is 1mm-1.3 mm. When the laser grooves are discontinuously arranged, namely the same laser groove comprises a plurality of short grooves on the same extension line, a form similar to a dotted line is formed, the distance between the end parts of the adjacent short grooves in the same laser groove is 0.2mm-0.7mm, and the short grooves on the adjacent laser grooves are preferably arranged in a staggered manner. When the laser groove is opened discontinuously, the combination effect of the TCO conducting layer and the front passivation antireflection layer or the back passivation layer is increased, the laser ablation area is reduced, the damage to the silicon wafer is reduced, the opening pressure can be improved, and the efficiency of the cell can also be improved.
According to some preferred embodiments of the present invention, the area ratio (aperture ratio) of the front side laser groove to the front side passivation anti-reflection layer is smaller than the area ratio (aperture ratio) of the back side laser groove to the back side passivation layer. In some embodiments, the area of the front side laser grooves accounts for 1-6%, preferably 2.5% -2.7% of the area of the front side passivation anti-reflection layer; the area of the back laser groove accounts for 2-8%, preferably 2.8% -3.2% of the area of the back passivation layer. The open porosity is controlled within a certain range, the larger the open porosity is, the smaller the series resistance is, the better the contact is, the higher the filling factor of the battery is, but the efficiency of the battery piece can be reduced due to the damage of the laser to the surface. On the other hand, the structures of the front surface and the back surface of the silicon wafer in the battery are asymmetrical, for example, the front surface of the silicon wafer is provided with a P-N junction, a passivation layer and an antireflection layer are generally deposited on the front surface, the back surface of the silicon wafer is not provided with the P-N junction, and only the passivation layer structure is generally deposited on the back surface, so that the series resistance generated on the front surface and the back surface of the silicon wafer is different, the grooving positions of the front surface and the back surface of the silicon wafer are not corresponding, and the aperture ratio of the back surface is greater than that of the front surface, so that the better battery efficiency is achieved.
According to some preferred embodiments of the present invention, the depth of the front side laser groove is greater than or equal to the thickness of the front side passivation anti-reflection layer, and the depth of the back side laser groove is greater than or equal to the thickness of the back side passivation layer. The depth of the laser groove is equal to or larger than the thickness of the front passivation anti-reflection layer or the back passivation layer, so that the TCO conducting layer is directly contacted with the doping layer or the crystalline silicon substrate, the traditional secondary grid line is replaced, and the current collecting effect is achieved.
According to some preferred embodiments of the invention, the front TCO conductive layer and/or the back TCO conductive layer is a transparent conductive oxide material ITO. The transparent conductive oxide material ITO is a transparent conductive material, so that the shading area of the cell is reduced, meanwhile, the whole surface is coated with the TCO material, so that the transmission path of electrons is reduced, the crosstalk is reduced, and the efficiency of the solar cell is improved.
According to some preferred embodiments of the present invention, the front passivation anti-reflection layer is a SiNx stacked film, a SiNx/SiO stacked film, or a SiNx/sion x/SiO stacked film, and the back passivation layer is a SiNx stacked film, or Al2O3A laminated film of/SiNx or a laminated film of SiNx/SiOx. The front passivation anti-reflection layer reduces the reflection of light, so that more light enters the solar cell, and meanwhile, the surface of the solar cell is passivated, and the recombination loss of the front surface is reduced; the back passivation layer passivates the back surface, reducing recombination losses at the back surface.
The utility model also provides a solar wafer of including as above the battery piece structure.
The utility model also provides a photovoltaic module of including as above solar wafer.
Compared with the prior art, the utility model discloses an useful part lies in: the utility model discloses a battery piece structure, TCO conducting layer subtracts anti-layer or the mutual gomphosis of back passivation layer with positive passivation, and set up the laser tank and make TCO conducting layer and N type P type doped layer or crystal silicon substrate direct contact, collect the transmission carrier through transparent conductive film material (TCO conducting layer), replace conventional vice grid line, the shading area of front and back grid line that can significantly reduce, thereby greatly increase the utilization ratio of light, reduce the string of carrier transmission and hinder, be favorable to improving solar cell's conversion efficiency.
Detailed Description
In order to make the technical solution of the present invention better understood, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.
Example 1 solar cell and photovoltaic Module
The photovoltaic module in this embodiment includes front bezel, preceding encapsulated layer, battery layer, back encapsulated layer and back plate from top to bottom in proper order, and wherein, the battery layer is formed after a plurality of battery pieces regular spread. As shown in fig. 1-3, the solar cell in this embodiment has a structure that includes, from top to bottom, a frontmain gate line 4, a front TCOconductive layer 5, and a front passivation layerThe thin film transistor structure comprises aantireflection layer 6, an N/Ptype doping layer 7, a P/N typecrystalline silicon substrate 8, a back passivation layer 9, a back TCOconductive layer 10 and a backmain grid line 11. In this embodiment, the front TCOconductive layer 5 and the back TCOconductive layer 10 are ITO, which is a transparent conductive oxide material. The front passivationanti-reflection layer 6 is a SiNx film, and the back passivation layer 9 is Al2O3A laminated film of/SiNx. The frontmain gate line 4 and the backmain gate line 11 are electrodes 1.
The front passivationanti-reflection layer 6 is provided with afront laser groove 2 formed by laser, and the front TCOconductive layer 5 is filled in thefront laser groove 2 and covers the front passivationanti-reflection layer 6; the back passivation layer 9 has aback laser groove 2 opened by laser, and the back TCOconductive layer 10 is filled in theback laser groove 2 and covers the back passivation layer 9. So that the front TCOconductive layer 5 and the front passivationanti-reflection layer 6 are mutually embedded, and the back TCOconductive layer 10 and the back passivation layer 9 are mutually embedded. The depth of thefront laser groove 2 is consistent with the thickness of the front passivationanti-reflection layer 6, and the depth of theback laser groove 2 is consistent with the thickness of the back passivation layer 9, so that the TCO conducting layer is in direct contact with thedoping layer 7 or thecrystalline silicon substrate 8, the traditional secondary grid line is replaced, and the current collection effect is achieved.
In this embodiment, the widths of thefront laser groove 2 and theback laser groove 2 obtained by laser grooving are 35 um; the depth is 1 um. Thefront laser groove 2 and theback laser groove 2 are arranged at positions corresponding to the auxiliary grid lines in the traditional battery piece, and the distance between theadjacent laser grooves 2 is as follows: the distance between theadjacent laser grooves 2 on the back surface is 1mm-1.1mm, and the distance between thelaser grooves 2 on the front surface is 1.15mm-1.25 mm. The aperture ratio of theback laser groove 2 in this embodiment is: 3.0 percent; the aperture ratio of the front laser was 2.6%.
In this embodiment, thefront laser groove 2 and theback laser groove 2 are provided intermittently, that is, thesame laser groove 2 includes a plurality of short grooves on the same extension line, so as to form a form similar to a dotted line, and the distance between the end portions of the adjacent short grooves in thesame laser groove 2 is 0.5 mm. When thelaser groove 2 is discontinuously opened, the combination effect of the TCO conducting layer and the front passivationanti-reflection layer 6 or the back passivation layer 9 is increased, the ablation area of laser is reduced, the damage to the silicon wafer 3 is reduced, and the opening pressure Uoc is improved. In other embodiments, when the laser grooves are discontinuously arranged, the short grooves in the adjacent laser grooves are staggered; or eachfront laser groove 2 and/or eachback laser groove 2 may be continuously opened, as shown in fig. 4.
The embedding in this embodiment is to set alaser groove 2 at a position corresponding to a conventional sub-grid line on the front passivationanti-reflection layer 6 or the back passivation layer 9, and then deposit a TCO conductive layer, so that the TCO conductive layer is embedded with the front passivationanti-reflection layer 6 or the back passivation layer 9, and set thelaser groove 2 so that the TCO conductive layer is in direct contact with the N-type/P-type doping layer 7 or thecrystalline silicon substrate 8, and collect and transmit carriers through a transparent conductive film material (TCO conductive layer), so as to replace a conventional sub-grid line, so that the light shielding areas of the front and back grid lines can be greatly reduced, thereby greatly increasing the utilization rate of light, reducing the crosstalk of carrier transmission, and being beneficial to improving the conversion efficiency of the solar cell.
Example 2 preparation method of solar cell sheet
The preparation method of the high-efficiency solar cell of the embodiment comprises the following steps: s1: texturing; s2: diffusing; s3: SE heavy doping S4: etching and back polishing; s5: annealing; s6: depositing SiNx on the front surface; s7: back side Al2O3/SiNx deposition; s8: laser grooving on the front surface; s9: laser grooving on the back; s10: annealing; s11: depositing a front TCO; s12: back TCO deposition; s13: printing and drying a back electrode; s14: printing an Ag main grid on the front surface, and sintering at low temperature.
Each step is as follows:
step S1: texturing method
A P-type monocrystalline silicon wafer is selected as a base material (a crystalline silicon substrate) and subjected to a texturing process. And forming a textured surface on the surface of the silicon wafer by using a wet etching technology, wherein the weight reduction is controlled to be 0.6g, and the reflectivity is controlled to be 12%.
Step S2: diffusion
And performing a diffusion process on the crystalline silicon substrate to form a diffusion layer.
Step S3: SE heavy doping
And carrying out SE doping on the diffusion layer to form an N-type doping layer.
Step S4: etching and back polishing
And etching and back polishing the silicon wafer with the N-type doped layer.
Step S5: annealing
And carrying out an oxidation annealing process on the silicon wafer.
Step S6: front side SiNx deposition
And performing a SiNx deposition process on the front surface of the silicon wafer to prepare a silicon nitride front passivation anti-reflection layer, wherein the thickness of the silicon nitride front passivation anti-reflection layer is controlled to be 70nm, and the refractive index is controlled to be 2.2.
Step S7: back side Al2O3/SiNx deposition
Carrying out Al on the back of the silicon wafer2O3/SiNx deposition process to prepare Al2O3And a/SiNx back passivation layer with the thickness controlled at 100 nm.
Step S8: front laser grooving
And carrying out laser grooving treatment on the front passivation anti-reflection layer on the front side of the silicon wafer. Grooving the SiNx passivation antireflection film on the front surface of the silicon wafer through laser equipment, wherein the thickness of the front surface laser groove is consistent with that of the front surface passivation antireflection layer, and the exposed silicon at the grooving position just contacts with the TCO transparent conductive film to collect transmitted carriers.
Step S9: back laser grooving
Al on the back of the silicon wafer by laser equipment2O3And grooving the SiNx passivation film (back passivation layer), wherein the thickness of the formed back laser groove is consistent with that of the back passivation layer, and the exposed silicon at the grooving position is just in contact with the TCO transparent conductive film to collect the transmitted current carriers.
In steps S8 and S9, the laser grooves formed by the laser device are used, and the opening ratio of the back laser grooves is: 3.0 percent; the aperture ratio of the front laser was 2.6%. Adopting 532nm-556nm green laser to perform slotting, wherein the parameters are as follows: the laser power is 20w, and the laser frequency is 900 KHz. The widths of the front laser groove and the back laser groove obtained by laser grooving are 35 um; the depth is 1 um. The distance between adjacent laser grooves is as follows: the distance between the adjacent laser grooves on the back surface is 1mm-1.1mm, and the distance between the laser grooves on the front surface is 1.15mm-1.25 mm. The laser grooves are discontinuously arranged, and the distance between the end parts of the adjacent short grooves in the same laser groove is 0.5 mm.
Step S10: annealing
And carrying out an oxidation annealing process on the silicon wafer.
Step S11: front side TCO deposition
And carrying out TCO deposition process on the front side of the silicon wafer to form a front TCO layer, wherein the TCO material can be in contact with the silicon wafer anode exposed in the step S8.
Step S12: backside TCO deposition
And carrying out TCO deposition process on the back of the silicon wafer to form a back TCO layer, wherein the TCO material can be in contact with the silicon wafer cathode exposed in the step S9.
In steps S11 and S12, a transparent conductive oxide material ITO is deposited using a PVD or RPD apparatus to form a TCO conductive layer, the thickness of the ITO being controlled at 60 nm.
Step S13: back electrode printing and drying
And printing and drying a back electrode on the back of the silicon wafer to form a back main grid line.
Step S14: front printing Ag main grid
And carrying out silk-screen printing and low-temperature sintering on the front side of the silicon wafer to form the front side main grid line.
In steps S13 and S14, silver paste is printed on TCO using a screen printing process and sintered at a low temperature, with the sintering temperature controlled at 220 ℃.
The steps are distinguished and numbered for convenience of description and understanding, and in actual preparation, some of the steps such as deposition of steps S6 and S7, laser grooving of steps S8 and S9, electrode printing of steps S11 and S12, and the like can be performed simultaneously or sequentially.
Example 3
The structure of the cell in this embodiment is substantially the same as that in embodiment 1, except that the laser grooves in this embodiment are continuously formed.
Comparative example 1
The back structure of the cell sheet in this comparative example is substantially the same as that of example 1, and the front structure is the same as that of a conventional PERC cell, that is, the front surface of the cell sheet is, from top to bottom: metal electrode, passivation anti-reflection layer, N+A diffusion layer,A silicon substrate.
Comparative example 2
The structure of the front side of the cell in the comparative example is basically the same as that of the embodiment 1, and the structure of the back side of the cell is the same as that of the traditional PERC cell, namely the back side of the cell sequentially comprises from bottom to top: metal electrode, passivation layer, silicon substrate.
Comparative example 3
The cell in this comparative example was a conventional PERC cell.
Comparative example 4
The cell front side structure and the back side structure in this comparative example were substantially the same as those in example 1, but the silicon wafer had the same open area ratio in the front side as in the back side and the same positions of the laser grooves.
Example 4 discussion of testing and results
The cells of examples 1 and 3 and comparative examples 1 to 3 were tested for correlation performance using a conventional hall tester for testing crystalline silicon solar cells. The test results are given in the following table:
TABLE 1 test results
|  | Uoc | Jsc | FF | Eta | 
| Example 2 | 0.6895 | 41.526 | 80.45% | 23.03% | 
| Example 3 | 0.6893 | 41.521 | 80.59% | 23.06% | 
| Comparative example 1 | 0.6892 | 40.659 | 81.11% | 22.73% | 
| Comparative example 2 | 0.6893 | 41.531 | 80.55% | 23.06% | 
| Comparative example 3 | 0.6890 | 40.631 | 81.65% | 22.86% | 
| Comparative example 4 | 0.6897 | 41.522 | 80.18% | 22.96% | 
The results of the above table show that: the transparent conductive film is used for replacing the traditional slurry, the shading is reduced, the short-circuit current density Jsc is improved, the improvement is about 0.9A, meanwhile, the open voltage Uoc is improved to a small extent, but the conductivity of the transparent conductive film ITO is lower than that of the traditional metal conductive slurry, so that the FF can be reduced by using the transparent conductive film, the overall efficiency is still improved by 0.15%, the metal conductive slurry is not used, the cost of the battery piece is greatly reduced, and the cost reduction effect is achieved.
The utility model relates to a high-efficient solar wafer and preparation method thereof through the technology advantage of combining heterojunction solar cell and crystalline silicon solar cell's technology a bit, provides a new high-efficient solar cell's preparation method. The utility model discloses a preparation method of solar wafer, the laser groove is seted up to the position that corresponds traditional fly line on positive passivation antireflection layer or the back passivation layer, later the TCO conducting layer of redeposition, make TCO conducting layer and positive passivation antireflection layer or the mutual gomphosis of back passivation layer, and set up the laser groove and make TCO conducting layer and doping layer or crystal silicon substrate direct contact, collect the transmission carrier through transparent conductive film material (TCO conducting layer), replace conventional fly line, the shading area of front and back grid line that can significantly reduce, thereby greatly increase the utilization ratio of light, reduce the string resistance of carrier transmission, be favorable to improving solar cell's conversion efficiency.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, so as not to limit the protection scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.