CN117253933A - Solar cell and preparation method thereof - Google Patents

Solar cell and preparation method thereof Download PDF

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CN117253933A
CN117253933A CN202311321472.2A CN202311321472A CN117253933A CN 117253933 A CN117253933 A CN 117253933A CN 202311321472 A CN202311321472 A CN 202311321472A CN 117253933 A CN117253933 A CN 117253933A
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polysilicon layer
doped polysilicon
region
layer
doping concentration
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王子港
陈达明
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Trina Solar Co Ltd
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Trina Solar Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H01L31/182—Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1868—Passivation

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Abstract

The application relates to a solar cell and a preparation method thereof. The solar cell comprises a silicon wafer and a passivation contact structure positioned on the back surface of the silicon wafer; the passivation contact structure comprises a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer which are sequentially arranged in a direction away from the back surface of the silicon wafer; the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer respectively comprise a part positioned in a first area and a part positioned in a second area, wherein the first area is an area corresponding to the back electrode, and the second area is other areas except the area corresponding to the back electrode; the element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region. The passivation contact structure of the solar cell can effectively reduce the recombination of metal and nonmetal areas, can also reduce the parasitic absorption problem of the polysilicon layer to light, and is beneficial to improving the utilization rate of the cell to light.

Description

Solar cell and preparation method thereof
Technical Field
The application relates to the technical field of solar cells, in particular to a solar cell and a preparation method thereof.
Background
In the passivation contact structure of the current solar cell, the polysilicon layer has serious parasitic absorption to light, the utilization rate of the cell to light can be greatly reduced by growing the polysilicon layer with excessively thick whole surface of the silicon wafer, and further, the short-circuit current of the cell is reduced, and the utilization rate of the cell to light can be ensured while the recombination of metal and nonmetal areas is effectively reduced, so that the problem which needs to be solved urgently at present is solved.
In the current research progress, the provided solution is mainly realized by adopting different thicknesses of the polysilicon layer in the metal contact area and the nonmetal contact area, and the thickness of the polysilicon layer in the metal contact area is higher than that of the nonmetal contact area, so that the metal contact area has good passivation effect, the compounding of the metal and the nonmetal area is reduced, the shielding of the polysilicon layer in the nonmetal contact area on sunlight is reduced, and the light absorption efficiency is improved. However, the process of the above solution is complicated, and there are still problems of low light utilization and battery efficiency.
Disclosure of Invention
Based on this, it is necessary to provide a solar cell and a method for manufacturing the same, which are simple in process and capable of improving light utilization efficiency and cell efficiency at the same time.
The application provides a solar cell, which comprises a silicon wafer and a passivation contact structure positioned on the back surface of the silicon wafer;
the passivation contact structure comprises a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer which are sequentially arranged in a direction away from the back surface of the silicon wafer;
the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer respectively comprise a part positioned in a first area and a part positioned in a second area, wherein the first area is an area corresponding to a back electrode, and the second area is other areas except the area corresponding to the back electrode;
the element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region.
In one embodiment, the element doping concentration of the portion of the second doped polysilicon layer located in the first region is lower than the element doping concentration of the portion of the second doped polysilicon layer located in the second region, and the difference in element doping concentrations is no more than 20% of the element doping concentration of the portion of the second doped polysilicon layer located in the second region.
In one embodiment, the element doping concentration of the portion of the second doped polysilicon layer located in the first region and the element doping concentration of the portion of the second doped polysilicon layer located in the second region are respectively and independently greater than 1E20cm -3 。
In one embodiment, the first doped polysilicon layer has a higher elemental doping concentration in a portion of the first region than in a portion of the second region, and the difference in elemental doping concentrations is no more than 20% of the elemental doping concentration in a portion of the first doped polysilicon layer in the second region.
In one embodiment, the element doping concentrations of the portion of the first doped polysilicon layer located in the first region and the portion of the first doped polysilicon layer located in the second region are respectively and independently 1E19cm -3 ～1E20cm -3 。
In one embodiment, the thickness of the first doped polysilicon layer is 5nm to 100nm.
In one embodiment, the second doped polysilicon layer has an element doping concentration 2-10 times higher in a portion of the first region than in a portion of the second doped polysilicon layer.
In one embodiment, the element doping concentration of the portion of the second doped polysilicon layer located in the first region and the element doping concentration of the portion of the second doped polysilicon layer located in the second region are respectively and independently 1E19cm -3 ～1E21cm -3 。
In one embodiment, the first doped polysilicon layer has an element doping concentration 2-10 times higher in a portion of the first region than in a portion of the second region.
In one embodiment, the element doping concentrations of the portion of the first doped polysilicon layer located in the first region and the portion of the first doped polysilicon layer located in the second region are respectively and independently 1E19cm -3 ～1E20cm -3 。
In one embodiment, the thickness of the first doped polysilicon layer is 5nm to 100nm.
In one embodiment, the element doping concentration of the first doped polysilicon layer is less than or equal to the element doping concentration of the second doped polysilicon layer.
In one embodiment, the thickness of the second doped polysilicon layer is 10nm to 200nm.
In one embodiment, the material of the first oxide layer is silicon oxide.
In one embodiment, the thickness of the first oxide layer is 1nm to 3nm.
In one embodiment, the material of the second oxide layer is silicon oxide.
In one embodiment, the thickness of the second oxide layer is 1nm to 5nm.
The application also provides a preparation method of the solar cell, which comprises the following steps:
forming a passivation contact structure on the back of the silicon wafer;
the passivation contact structure comprises a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer which are sequentially arranged in a direction away from the back surface of the silicon wafer;
the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer respectively comprise a part positioned in a first area and a part positioned in a second area, wherein the first area is an area corresponding to a back electrode, and the second area is other areas except the area corresponding to the back electrode;
the element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region.
In one embodiment, the element doping concentration of the portion of the second doped polysilicon layer located in the first region is lower than the element doping concentration of the portion of the second doped polysilicon layer located in the second region, and the difference between the element doping concentrations is not more than 20% of the element doping concentration of the portion of the second doped polysilicon layer located in the second region, and the preparation of the passivation contact structure includes the steps of:
Sequentially forming a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer on the back surface of the silicon wafer in the direction away from the silicon wafer, and then carrying out annealing treatment;
carrying out laser treatment on the part of the second doped polysilicon layer located in the first region, wherein doping elements of the part of the second doped polysilicon layer located in the first region diffuse to the part of the second oxide layer located in the first region and the part of the first doped polysilicon layer located in the first region, so that the doping concentration of the elements of the part of the first doped polysilicon layer located in the first region is increased, and the doping concentration of the elements of the part of the second doped polysilicon layer located in the first region is reduced;
the conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green light skin second laser or infrared continuous laser; the laser power is 10W-20W.
In one embodiment, the doping concentration of the element of the portion of the second doped polysilicon layer located in the first region is 2-10 times higher than the doping concentration of the element of the portion of the second doped polysilicon layer located in the second region, and the preparation of the passivation contact structure includes the following steps:
Sequentially forming a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer on the back surface of the silicon wafer in the direction away from the silicon wafer, and then carrying out annealing treatment;
forming a doped source layer on the second doped polysilicon layer after annealing treatment;
carrying out laser treatment on the part of the doping source layer located in the first region, wherein doping elements of the part of the doping source layer located in the first region diffuse to the part of the second doping polysilicon layer located in the first region, the part of the second oxide layer located in the first region and the part of the first doping polysilicon layer located in the first region, so that the element doping concentration of the part of the first doping polysilicon layer located in the first region and the element doping concentration of the part of the second doping polysilicon layer located in the first region are increased;
the conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green nanosecond laser or infrared continuous laser; the laser power is 10W-20W.
In one embodiment, the dopant source layer is a PSG or a BSG.
In one embodiment, the thickness of the doping source layer is 10 nm-100 nm.
In one embodiment, after the step of performing the laser treatment, the method further comprises the steps of:
and removing the doping source layer.
The passivation contact structure of the back of the solar cell comprises the first oxide layer, the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer which are sequentially arranged in the direction away from the silicon wafer, wherein the element doping concentration of the first doped polysilicon layer at the part corresponding to the first area of the back electrode is higher than that of the part not corresponding to the second area of the back electrode. The solar cell can be prepared by simple procedures, and is more beneficial to large-scale popularization and application.
Drawings
Fig. 1 is a schematic structural diagram of a solar cell in an embodiment.
Reference numerals illustrate:
1: a solar cell; 10: a silicon wafer; 20: passivating the contact structure; 210: a first oxide layer; 220: a first doped polysilicon layer; 230: a second oxide layer; 240: a second doped polysilicon layer; 250: a first region; 260: a second region; 30: a back electrode; 40: an antireflection film layer.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the embodiments that are illustrated in the appended drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
As shown in fig. 1, the present application provides a solar cell 1, which includes a silicon wafer 10 and a passivation contact structure 20 located on the back surface of the silicon wafer 10.
The passivation contact structure 20 includes a first oxide layer 210, a first doped polysilicon layer 220, a second oxide layer 230, and a second doped polysilicon layer 240 sequentially disposed in a direction away from the back surface of the silicon wafer 10.
The first doped polysilicon layer 220, the second oxide layer 230, and the second doped polysilicon layer 240 respectively include a portion located in the first region 250 and a portion located in the second region 260, the first region 250 being a region corresponding to the rear electrode 30, and the second region 260 being the remaining region excluding the region corresponding to the rear electrode 30.
The first doped polysilicon layer 220 has a higher elemental doping concentration in the portion of the first region 250 than in the portion of the first doped polysilicon layer 220 that is in the second region 260.
The passivation contact structure 20 on the back of the solar cell 1 provided by the application comprises the first oxide layer 210, the first doped polysilicon layer 220, the second oxide layer 230 and the second doped polysilicon layer 240 which are sequentially arranged in the direction far away from the silicon wafer 10, wherein the element doping concentration of the first doped polysilicon layer 210 in the part corresponding to the first region 250 of the back electrode is higher than that in the part not corresponding to the second region 260 of the back electrode, the passivation contact structure 20 has a good passivation effect, the recombination of metal and non-metal regions can be effectively reduced, in addition, the second oxide layer 230 can improve the back reflectivity, the element doping concentration of the part of the first doped polysilicon layer 210 in the second region 260 is lower than that in the part located in the first region 250, the light absorption can be reduced, the parasitic absorption problem of the polysilicon layer to light in the passivation contact structure 20 can be reduced by the combination of the two effects, and the utilization ratio of the battery to light can be improved. The solar cell 1 can be prepared by simple procedures, and is more beneficial to large-scale popularization and application.
It will be appreciated that the doping elements in the first doped polysilicon layer 220 and the second doped polysilicon layer 240 in this application may be selected according to conventional requirements in the solar cell field, and may be, for example, but not limited to, phosphorus doping or boron doping, etc.
In this application, the element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 and the portion located in the second region 260 can be divided into two cases:
first kind: the second doped polysilicon layer 240 has a lower elemental doping concentration in the portion of the first region 250 than in the portion of the second doped polysilicon layer 240 in the second region 260.
Second kind: the second doped polysilicon layer 240 has a higher elemental doping concentration in the portion of the first region 250 than in the portion of the second doped polysilicon layer 240 in the second region 260.
In some of these embodiments, the element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is lower than the element doping concentration of the portion of the second doped polysilicon layer 240 located in the second region 260, and the difference in element doping concentrations is no more than 20% of the element doping concentration of the portion of the second doped polysilicon layer located in the second region. The element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is reduced compared with the element doping concentration of the portion located in the second region 260, but still controlled within a certain gap, so that it is ensured that the contact resistance of the portion of the second doped polysilicon layer 240 located in the first region 250 and the back electrode 30 can be kept low, and good battery efficiency is achieved.
Further, the doping concentration of the element of the second doped polysilicon layer 240 at the portion of the first region 250 and the doping concentration of the element of the second doped polysilicon layer 240 at the portion of the second region 260 are respectively and independently greater than 1E20cm -3 . When the elemental doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is lower than the elemental doping concentration of the portion of the second doped polysilicon layer 240 located in the second region 260, the elemental doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 remains greater than 1E20cm -3 It is possible to ensure a low contact resistance.
Further, the first doped polysilicon layer 220 has a higher element doping concentration in the portion of the first region 250 than in the portion of the first doped polysilicon layer 220 in the second region 260, and the difference in element doping concentration is no more than 20% of the element doping concentration in the portion of the first doped polysilicon layer in the second region. The lower doping concentration of the element in the portion of the first doped polysilicon layer 220 located in the second region 260 is advantageous for reducing light absorption.
Further, the element doping concentrations of the portion of the first doped polysilicon layer 220 located in the first region 250 and the portion of the first doped polysilicon layer 220 located in the second region 250 are respectively and independently 1E19cm -3 ～1E20cm -3 . It will be appreciated that the first doped polysilicon layer 220 has elements located in portions of the first region 250 and in portions of the second region 260The doping concentrations can be, for example, but not limited to, 1E19cm each independently -3 、3E19cm -3 、5E19cm -3 、7E19cm -3 、9E19cm -3 、1E20cm -3 Etc.
Further, the thickness of the first doped polysilicon layer 220 is 5nm to 100nm. The thickness of the first doped polysilicon layer 220 is controlled within a proper range, so that the light absorption level of the first doped polysilicon layer 220 can be controlled, and the influence on electrical performance parameters such as short circuit current of the solar cell is avoided. It is understood that the thickness of the first doped polysilicon layer 220 may be, for example, but not limited to, 5nm, 15nm, 20nm, 50nm, 80nm, 100nm, etc.
In other embodiments, the second doped polysilicon layer 240 has an element doping concentration that is 2-10 times higher in the portion of the first region 250 than in the portion of the second doped polysilicon layer 240 that is in the second region 260. The second doped polysilicon layer 240 has a higher element doping concentration at the portion of the first region 250, and can further reduce the contact resistance after contacting the back electrode 30, thereby greatly improving the cell efficiency. It is understood that the element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 may be, for example, but not limited to, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, etc., higher than the element doping concentration of the portion located in the second region 260.
Further, the doping concentration of the element of the second doped polysilicon layer 240 at the portion of the first region 250 and the doping concentration of the element of the second doped polysilicon layer 240 at the portion of the second region 260 are respectively 1E19cm -3 ～1E21cm -3 . When the elemental doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is higher than the elemental doping concentration of the portion of the second doped polysilicon layer 240 located in the second region 260, the elemental doping concentration of the second doped polysilicon layer 240 is maintained at 1E19cm -3 ～1E21cm -3 Within a range of (2), a low contact resistance can be ensured. It will be appreciated that the elemental doping concentration of the portion of the second doped polysilicon layer 240 that is located in the first region 250 and the elemental doping concentration of the portion that is located in the second region 260 may, for example, but not beLimited to 1E19cm each independently -3 、3E19cm -3 、5E19cm -3 、7E19cm -3 、9E19cm -3 、1E20cm -3 、3E20cm -3 、5E20cm -3 、7E20cm -3 、9E20cm -3 、1E21cm -3 Etc.
Further, the first doped polysilicon layer 220 has an element doping concentration 2 to 10 times higher in the portion of the first region 250 than in the portion of the first doped polysilicon layer 220 located in the second region 260. The lower doping concentration of the element in the portion of the first doped polysilicon layer 220 located in the second region 260 is advantageous for reducing light absorption. It is understood that the elemental doping concentration of the portion of the first doped polysilicon layer 220 located in the first region 250 may be, for example, but not limited to, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, etc., higher than the elemental doping concentration of the portion located in the second region 260.
Further, the element doping concentrations of the portion of the first doped polysilicon layer 220 located in the first region 250 and the portion of the first doped polysilicon layer 220 located in the second region 250 are respectively and independently 1E19cm -3 ～1E20cm -3 . It will be appreciated that the elemental doping concentrations of the portion of the first doped polysilicon layer 220 located in the first region 250 and the portion located in the second region 260 may be, for example, but not limited to, 1E19cm each independently -3 、3E19cm -3 、5E19cm -3 、7E19cm -3 、9E19cm -3 、1E20cm -3 Etc.
Further, the thickness of the first doped polysilicon layer 220 is 5nm to 100nm. The thickness of the first doped polysilicon layer 220 is controlled within a proper range, so that the light absorption level of the first doped polysilicon layer 220 can be controlled, and the influence on electrical performance parameters such as short circuit current of the solar cell is avoided. It is understood that the thickness of the first doped polysilicon layer 220 may be, for example, but not limited to, 5nm, 15nm, 20nm, 50nm, 80nm, 100nm, etc.
In some embodiments, the element doping concentration of the first doped polysilicon layer 220 is less than or equal to the element doping concentration of the second doped polysilicon layer 240, so that the light absorption coefficient is reduced, the light absorption of the back polysilicon film is reduced, and further, the combination of the effect of improving the back reflectivity of the second oxide layer 230 and the effect of improving the back reflectivity of the second doped polysilicon layer can further improve the back reflectivity, reduce the light absorption, and greatly improve the light utilization.
In some of these embodiments, the thickness of the second doped polysilicon layer 240 is 10nm to 200nm. The thickness of the second doped polysilicon layer 240 is controlled within a proper range, so that the light absorption level of the second doped polysilicon layer 240 can be controlled, and the influence on electrical performance parameters such as short-circuit current of the solar cell 1 can be avoided. It is understood that the thickness of the second doped polysilicon layer 240 may be, for example, but not limited to, 10nm, 50nm, 100nm, 150nm, 200nm, and the like.
In some embodiments, the material of the first oxide layer 210 is one or more of silicon oxide and aluminum oxide. Preferably, the material of the first oxide layer 210 is silicon oxide, so that the passivation and tunneling effects are better.
Further, the thickness of the first oxide layer 210 is < 3nm. Controlling the thickness of the first oxide layer 210 within a suitable range may ensure good passivation and tunneling. It is understood that the thickness of the first oxide layer 210 may be, for example, but not limited to, 0.5nm, 1nm, 1.5nm, 2nm, 2.5nm, and the like. Preferably, the thickness of the first oxide layer 210 is 1nm to 3nm.
In some embodiments, the material of the second oxide layer 230 is silicon oxide. Silicon oxide may increase back reflection and tunneling effects.
Further, the thickness of the second oxide layer 230 is 1nm to 5nm. Controlling the second oxide layer 230 within a suitable thickness range may ensure good back reflection and tunneling effects. It is understood that the thickness of the second oxide layer 230 may be, for example, but not limited to, 1nm, 2nm, 3nm, 4nm, 5nm, and the like.
In some of these embodiments, an anti-reflective film layer 40 is also provided on the side of the second doped polysilicon layer 240 facing away from the silicon wafer 10. The anti-reflection film layer 40 can further reduce the light reflection on the surface of the silicon wafer 10. It is understood that the anti-reflection film layer 40 may be, for example, but not limited to, at least one of silicon nitride and aluminum oxide, and further may have a single-layer structure or a stacked-layer structure.
In some of these embodiments, a back electrode 30 is further included in the first region 250 of the passivation contact structure 20, the back electrode 30 being in direct contact with the surface of the side of the second doped polysilicon layer 240 facing away from the silicon wafer 10. It will be appreciated that the back electrode 30 may be prepared using screen printing and sintering techniques. Preferably, the back electrode 30 is a silver electrode or a silver aluminum electrode.
It will be appreciated that the front side of the silicon wafer 10 is a front side structure of a conventional solar cell, for example, in one embodiment, the front side structure further includes a passivation layer and an anti-reflection film layer sequentially disposed on the front side of the silicon wafer 10 in a direction away from the silicon wafer 10, and a front side electrode on the front side of the silicon wafer 10 and in direct contact with the front side of the silicon wafer 10. The passivation layer may have a positive passivation effect, for example, may be aluminum oxide. The front side anti-reflection film layer may have an effect of reducing light reflection, and may be, for example, a single layer or a stacked layer of silicon nitride. The front electrode can be prepared by screen printing and sintering technology, and is preferably a silver electrode or a silver-aluminum electrode.
The application also provides a preparation method of the solar cell 1, which comprises the following steps:
passivation contact structures 20 are formed on the back side of the silicon wafer 10.
The passivation contact structure 20 includes a first oxide layer 210, a first doped polysilicon layer 220, a second oxide layer 230, and a second doped polysilicon layer 240 sequentially disposed in a direction away from the back surface of the silicon wafer 10.
The first doped polysilicon layer 220, the second oxide layer 230, and the second doped polysilicon layer 240 respectively include a portion located in the first region 250 and a portion located in the second region 260, the first region 250 being a region corresponding to the rear electrode 30, and the second region 260 being the remaining region excluding the region corresponding to the rear electrode 30.
The first doped polysilicon layer 220 has a higher elemental doping concentration in the portion of the first region 250 than in the portion of the first doped polysilicon layer 220 that is in the second region 250.
It will be appreciated that the solar cell prepared by the preparation method described above is the solar cell 1 described in any of the above embodiments.
The preparation method of the solar cell 1 does not need to adopt different thickness designs for the first doped polysilicon layer 220, the second oxide layer 230 and the second doped polysilicon layer 240 which are positioned at the part of the first region 250 and the part of the second region 260, and has simple preparation process, and in effect, because the doping concentration of elements of the part of the first doped polysilicon layer 220 which is positioned at the second region 260 is lower than that of the first region 250, parasitic absorption of light by the polysilicon layer can be reduced, the utilization rate of light by the cell can be improved, the short-circuit current of the cell can be further improved, the recombination of metal and nonmetal regions can be effectively reduced, and good passivation effect can be realized.
In some embodiments, the element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is lower than the element doping concentration of the portion of the second doped polysilicon layer 240 located in the second region 260, and the difference in element doping concentrations is not more than 20% of the element doping concentration of the portion of the second doped polysilicon layer located in the second region, and the preparation of the passivation contact structure 20 includes the following steps S101 to S102:
step S101: a first oxide layer 210, a first doped polysilicon layer 220, a second oxide layer 230, and a second doped polysilicon layer 240 are sequentially formed on the back surface of the silicon wafer 10 in a direction away from the silicon wafer 10, and then an annealing process is performed.
Further, the first oxide layer 210 may be formed by, for example, thermal oxygen or chemical vapor deposition (PECVD).
Further, the first doped polysilicon layer 220 may be formed by, for example, low Pressure Chemical Vapor Deposition (LPCVD) deposition or chemical vapor deposition (PECVD).
Further, the second oxide layer 230 may be formed by, for example, thermal oxygen or chemical vapor deposition (PECVD).
Further, the second doped polysilicon layer 240 may be formed by, for example, low Pressure Chemical Vapor Deposition (LPCVD) deposition or chemical vapor deposition (PECVD).
Further, the deposited first doped polysilicon layer 220 and second doped polysilicon layer 240 may be further crystallized by an annealing process, thereby enhancing the conductivity of the polysilicon.
Further, the annealing conditions include: the temperature is 800-1000 ℃ and the time is 25-35 min.
It will be appreciated that conventional steps in the process of fabricating the solar cell 1, such as cleaning, texturing, diffusing, polishing, etc., of the silicon wafer 10 may also be included prior to forming the first oxide layer 210.
Step S102: the portion of the second doped polysilicon layer 240 located in the first region 250 is subjected to laser processing, and the doping element of the portion of the second doped polysilicon layer 240 located in the first region 250 is diffused to the portion of the second oxide layer 230 located in the first region 250 and the portion of the first doped polysilicon layer 220 located in the first region 250, so that the doping concentration of the element of the portion of the first doped polysilicon layer 220 located in the first region 250 is increased, and the doping concentration of the element of the portion of the second doped polysilicon layer 240 located in the first region 250 is decreased.
By scanning the portion of the second doped polysilicon layer 240 located in the first region 250 with the laser, the doped element in the second doped polysilicon layer 240 passes through the second oxide layer 230 and is pushed and diffused into the first doped polysilicon layer 220 by using the energy of the laser, although the doped concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is reduced, the doped concentration of the portion of the first doped polysilicon layer 220 located in the first region 250 is increased, and the second oxide layer 230 located in the portion of the first region 250 contains the doped element due to the diffusion effect of the doped element, so that the passivation contact structure 20 of the selective oxide layer+the selective doped concentration polysilicon film is finally formed, the metal recombination of the back metal contact region can be effectively reduced, the tunneling resistance of the second oxide layer 230 located in the first region 250 can be reduced, and the photoelectric conversion efficiency can be improved.
Further, the conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green light skin second laser or infrared continuous laser; the laser power is 10W-20W. It will be appreciated that the greater the power of the laser, the more the doped elements in the second doped polysilicon layer 240 can be pushed toward the second oxide layer 230 and the first doped polysilicon layer 220, the higher the back reflectivity, and the short-circuit current of the battery increases, but the doping concentration of the elements on the surface of the second doped polysilicon layer 240 at the portion of the first region 250 decreases, so that the contact resistance increases, and the battery efficiency decreases, and therefore, in order to avoid the influence of the contact resistance on the battery efficiency due to the excessive contact resistance, the laser power is preferably controlled to be 10W to 20W.
In other embodiments, the doping concentration of the element of the portion of the second doped polysilicon layer 240 located in the first region 250 is 2-10 times higher than the doping concentration of the element of the portion of the second doped polysilicon layer 240 located in the second region 260, and the preparation of the passivation contact structure 20 includes the following steps S201 to S204:
step S201: a first oxide layer 210, a first doped polysilicon layer 220, a second oxide layer 230, and a second doped polysilicon layer 240 are sequentially formed on the back surface of the silicon wafer 10 in a direction away from the silicon wafer 10, and then an annealing process is performed.
In step S201, the process conditions for forming the first oxide layer 210, the first doped polysilicon layer 220, the second oxide layer 230, the second doped polysilicon layer 240, and the annealing treatment are the same as those in step S101.
Step S202: after the annealing process, a dopant source layer is formed over the second doped polysilicon layer 240.
As will be appreciated, the doped source layer refers to a layer that may provide a source of doping elements for the first doped polysilicon layer 220 and the second doped polysilicon layer 230 in the passivation contact structure 20, and further, the doped source layer is PSG or BSG. The dopant source layer may be selected according to conventional requirements in the solar cell field, for example, PSG for phosphorus doping and BSG for boron doping.
Further, the thickness of the doped source layer is 10 nm-100 nm. The thickness of the formed doping source layer is controlled, so that the doping element has good diffusion effect in the subsequent laser treatment process. It is understood that the doping source layer may be, for example, but not limited to, 10nm, 30nm, 50nm, 80nm, 100nm, etc.
Step S203: the portion of the doped source layer located in the first region 250 is subjected to laser processing, and the doping elements of the portion of the doped source layer located in the first region 250 are diffused to the portion of the second doped polysilicon layer 240 located in the first region 250, the portion of the second oxide layer 230 located in the first region 250, and the portion of the first doped polysilicon layer 220 located in the first region 250, so that the doping concentration of the elements of the portion of the first doped polysilicon layer 220 located in the first region 250 and the doping concentration of the elements of the portion of the second doped polysilicon layer 240 located in the first region 250 are both increased.
By scanning the part of the doped source layer located in the first region 250 with the laser, the doped element in the doped source layer is diffused to the first doped polysilicon layer 220 through the second doped polysilicon layer 240 by utilizing the energy of the laser, so that the doped concentration of the element in the part of the second doped polysilicon layer 240 located in the first region 250 and the doped concentration of the element in the part of the first doped polysilicon layer 250 are both increased simultaneously compared with the doped concentration of the element in the part of the second region 260, and the doped element is contained in the second oxide layer 230 in the part of the first region 250 due to the diffusion effect of the doped element, so that the passivation contact structure 20 of the selective oxide layer and the selective doped concentration polysilicon film is formed, thereby not only effectively reducing the metal recombination of the back metal contact region and reducing the tunneling resistance of the second oxide layer 230 located in the first region 250, but also reducing the contact resistance between the back electrode 30 in the part of the first region 250 and the second doped polysilicon layer 240, and further improving the photoelectric conversion efficiency.
Further, the conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green nanosecond laser or infrared continuous laser; the laser power is 10W-20W.
Step S204: and removing the doping source layer.
It will be appreciated that the dopant source layer may be removed by methods conventional in the solar cell arts, for example, by cleaning with HF.
It will be appreciated that after the step of step S102 or step S204, the back side anti-reflection film layer 40 and the back side electrode 30 may be further prepared according to a conventional method in the solar cell field, and other structures such as a front side passivation layer, an anti-reflection film layer, a front side electrode may be further prepared according to a conventional method.
Further, the passivation layer on the front side may be formed by atomic deposition (ALD).
Further, the front and rear anti-reflection film layers 40 may be formed by a chemical vapor deposition (PECVD) method or an atomic deposition (ALD) method.
Further, the back electrode 30 and the front electrode may be formed by a screen printing technique.
The preparation method of the two passivation contact structures 20 can be completed by adding one laser device and one oxidation device, the cost of the crystalline silicon photovoltaic cell is not increased, the process cost is low, and the obtained passivation contact structure 20 has a good effect of reducing parasitic absorption of the polycrystalline silicon film and is easy to popularize in a large scale.
Compared with the traditional technology, the solar cell 1 prepared by the method can improve the photoelectric conversion efficiency of the cell by more than 0.2%.
The following are specific examples.
Example 1
A method for manufacturing a solar cell 1:
(1) The N-type silicon wafer 10 is cleaned and textured.
(2) Boron expansion: and carrying out a front boron diffusion process, wherein the deposition temperature of a boron source is about 900 ℃ and the advancing temperature is about 1000 ℃.
(3) Post-cleaning + backside polishing: the back surface BSG is removed with HF and the back surface of the wafer 10 is polished with KOH.
(4) A first oxide layer 210 and a first doped polysilicon layer 220 are back deposited: a first oxide layer 210 and a first doped polysilicon layer 220 are formed by chemical vapor deposition, wherein the first oxide layer 210 is silicon oxide with the thickness of 1.5nm, the first doped polysilicon layer 220 is 50nm with the thickness, the doping element is phosphorus, and the doping concentration is 5E19cm -3 。
(5) A second oxide layer 230 and a second doped polysilicon layer 240 are back deposited: depositing a second oxide layer 230 and a second doped polysilicon layer 240 by chemical vapor deposition, wherein the second oxide layer 230 is silicon oxide with a thickness of 2nm, and the second doped polysilicon layer 240 has a thickness of100nm, phosphorus as doping element, doping concentration of 2E20cm -3 。
(6) Annealing: annealing at 900 ℃ for 30min.
(7) And (3) laser treatment: scanning the portion of the second doped polysilicon layer 240 located in the first region 250 with picosecond laser having a wavelength of 355nm, the laser power being 10W, and using the energy of the laser to push phosphorus atoms therein to penetrate the portion of the second oxide layer 230 located in the first region 250, diffusing the phosphorus atoms to the portion of the first doped polysilicon layer 220 located in the first region 250, so that the doping concentration of the element in the portion of the first doped polysilicon layer 220 located in the first region 250 is increased to 5.2e19cm -3 The element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is reduced to 1.9e20cm -3 . The first region 250 corresponds to the rear electrode 30, and the second region 260 corresponds to the rest of the regions except for the rear electrode 30.
(8) Front side deposition of a front side passivation layer: and depositing a front passivation layer on the front surface of the silicon wafer 10 by adopting an atomic deposition method, wherein the front passivation layer is aluminum oxide.
(9) And depositing an antireflection film layer 40 on the front and back surfaces respectively: and respectively depositing an antireflection film layer 40 on the back side and the front side of the silicon wafer by using a chemical vapor deposition method, wherein the antireflection film layer 40 is silicon nitride.
(10) Electrode preparation: silver paste is printed on the front anti-reflection film layer by adopting a screen printing technology and is used as a front electrode, silver paste is printed on the back anti-reflection film layer 40 by adopting a screen printing technology to form a back electrode 30, the back electrode 30 is positioned in a first area 250 of the passivation contact structure 20, after sintering, the silver paste on the back is burnt through the anti-reflection film layer 40, the surface of the back electrode 30, which is away from the silicon wafer 10, and the surface of the second doped polysilicon layer 240 are in direct contact with the first area 250, the silver paste on the front is burnt through the front anti-reflection film layer and the passivation layer, and the front electrode is in direct contact with the front of the silicon wafer.
Example 2
Substantially the same as in example 1, except for the difference in step (7). Specifically:
(7) And (3) laser treatment: scanning with picosecond laser having a wavelength of 355nmThe second doped polysilicon layer 240 is located at the portion of the first region 250, the laser power is 20W, and the energy of the laser is used to push the phosphorus atoms therein to penetrate the portion of the second oxide layer 230 located at the first region 250, diffuse into the portion of the first doped polysilicon layer 220 located at the first region 250, so that the doping concentration of the element in the portion of the first doped polysilicon layer 220 located at the first region 250 is increased to 5.9e19cm -3 The element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is reduced to 1.7e20cm -3 . The first region 250 corresponds to the rear electrode 30, and the second region 260 corresponds to the rest of the regions except for the rear electrode 30.
Example 3
A method for manufacturing a solar cell 1:
(1) The N-type silicon wafer 10 is cleaned and textured.
(2) Boron expansion: and carrying out a front boron diffusion process, wherein the deposition temperature of a boron source is about 900 ℃ and the advancing temperature is about 1000 ℃.
(3) Post-cleaning + backside polishing: the back surface BSG is removed with HF and the back surface of the wafer 10 is polished with KOH.
(4) A first oxide layer 210 and a first doped polysilicon layer 220 are back deposited: a first oxide layer 210 and a first doped polysilicon layer 220 are formed by chemical vapor deposition, wherein the first oxide layer 210 is silicon oxide with the thickness of 1.5nm, the first doped polysilicon layer 220 is 50nm, the doping element is phosphorus, and the doping concentration is 3E19cm -3 。
(5) A second oxide layer 230 and a second doped polysilicon layer 240 are back deposited: a second oxide layer 230 and a second doped polysilicon layer 240 are formed by chemical vapor deposition, wherein the second oxide layer 230 is silicon oxide with a thickness of 2nm, the second doped polysilicon layer 240 has a thickness of 100nm, the doping element is phosphorus, and the doping concentration is 5E19cm -3 。
(6) Annealing: annealing at 900 ℃ for 30min.
(7) Back deposition of a doping source layer: using POCl 3 A layer of PSG is deposited on the surface of the second doped polysilicon layer 240 to a thickness of 50nm.
(8) And (3) laser treatment: the portion of the doped source layer PSG located in the first region 250 is scanned with a nanosecond laser having a wavelength of 550nm, the laser power is 15W, and the energy of the laser advances the diffusion of phosphorus atoms therein to the portion of the second doped polysilicon layer 240 located in the first region 250, the portion of the second oxide layer 230 located in the first region 250, and the portion of the first doped polysilicon layer 220 located in the first region 250, so that the element doping concentration of the portion of the first doped polysilicon layer 220 located in the first region 250 is higher than the element doping concentration of the portion located in the second region 260, and the element doping concentration of the portion of the second doped polysilicon layer 240 located in the first region 250 is higher than the element doping concentration of the portion located in the second region 260. The first region 250 corresponds to the rear electrode 30, and the second region 250 is the remaining region excluding the region corresponding to the rear electrode 30.
Wherein the portion of the passivation contact structure 20 located in the first region 250:
the first doped polysilicon layer 220 has an element doping concentration of 1E20cm -3 ；
The second oxide layer 230 contains a doping element;
the second doped polysilicon layer 240 has an elemental doping concentration of 2E20cm -3 ；
The portion of the passivation contact structure 20 located in the second region 260:
the first doped polysilicon layer 220 has an elemental doping concentration of 3E19cm -3 ；
The second oxide layer 230 does not contain a doping element;
the second doped polysilicon layer 240 has an elemental doping concentration of 5E19cm -3 。
(9) Front side deposition of a front side passivation layer: and depositing a front passivation layer on the front side of the silicon wafer by adopting an atomic deposition method, wherein the front passivation layer is alumina.
(10) And depositing an antireflection film layer 40 on the front and back surfaces respectively: and respectively depositing an antireflection film layer 40 on the back side and the front side of the silicon wafer by using a chemical vapor deposition method, wherein the antireflection film layer 40 is silicon nitride.
(11) Electrode preparation: silver paste is printed on the front anti-reflection film layer by adopting a screen printing technology and is used as a front electrode, silver paste is printed on the back anti-reflection film layer 40 by adopting a screen printing technology to form a back electrode 30, the back electrode 30 is positioned in a first area 250 of the passivation contact structure 20, after sintering, the silver paste on the back is burnt through the anti-reflection film layer 40, the surface of the back electrode 30, which is away from the silicon wafer 10, and the surface of the second doped polysilicon layer 240 are in direct contact with the first area 250, the silver paste on the front is burnt through the front anti-reflection film layer and the passivation layer, and the front electrode is in direct contact with the front of the silicon wafer.
Comparative example 1
A preparation method of a solar cell comprises the following steps:
a method for manufacturing a solar cell 1:
(1) And cleaning and texturing the N-type silicon wafer.
(2) Boron expansion: and carrying out a front boron diffusion process, wherein the deposition temperature of a boron source is about 900 ℃ and the advancing temperature is about 1000 ℃.
(3) Post-cleaning + backside polishing: the back surface BSG is removed with HF and the back surface of the wafer is polished with KOH.
(4) Depositing a first oxide layer and a first doped polysilicon layer on the back surface: depositing a first oxide layer and a first doped polysilicon layer by adopting a chemical vapor deposition method, wherein the first oxide layer is silicon oxide, the thickness is 1.5nm, the thickness of the first doped polysilicon layer is 150nm, the doping element is phosphorus, and the doping concentration is 2E20cm -3 。
(5) Annealing: annealing at 900 ℃ for 30min.
(6) Front side deposition of a front side passivation layer: and depositing a front passivation layer on the front side of the silicon wafer by adopting an atomic deposition method, wherein the front passivation layer is alumina.
(7) And respectively depositing antireflection film layers on the front surface and the back surface: and respectively depositing an antireflection film layer on the back side and the front side of the silicon wafer by using a chemical vapor deposition method, wherein the antireflection film layer is silicon nitride.
(8) Electrode preparation: and printing silver paste on the front anti-reflection film layer by adopting a screen printing technology, wherein the silver paste is used as a front electrode, the silver paste is printed on the back anti-reflection film layer by adopting the screen printing technology, so as to form a back electrode, the back electrode is positioned in a first area of a passivation contact structure, after sintering, the silver paste on the back is burnt through the anti-reflection film layer, the back electrode is in direct contact with the surface, which is away from the silicon wafer, of the second doped polysilicon layer, corresponding to the first area, the front silver paste is burnt through the front anti-reflection film layer and the passivation layer, and the front electrode is in direct contact with the front of the silicon wafer.
Comparative example 2
A preparation method of a solar cell comprises the following steps:
(1) And cleaning and texturing the N-type silicon wafer.
(2) Boron expansion: and carrying out a front boron diffusion process, wherein the deposition temperature of a boron source is about 900 ℃ and the advancing temperature is about 1000 ℃.
(3) Post-cleaning + backside polishing: the back surface BSG is removed with HF and the back surface of the wafer is polished with KOH.
(4) Depositing a first oxide layer and a first doped polysilicon layer on the back surface: depositing a first oxide layer and a first doped polysilicon layer by adopting a chemical vapor deposition method, wherein the first oxide layer is silicon oxide, the thickness is 1.5nm, the thickness of the first doped polysilicon layer is 50nm, the doping element is phosphorus, and the doping concentration is 5E19cm -3 。
(5) And depositing a second oxide layer and a second doped polysilicon layer on the back surface: depositing a second oxide layer and a second doped polysilicon layer by adopting a chemical vapor deposition method, wherein the second oxide layer is silicon oxide, the thickness is 2nm, the thickness of the second doped polysilicon layer is 100nm, the doping element is phosphorus, and the doping concentration is 2E20cm -3 。
(6) Annealing: annealing at 900 ℃ for 30min.
(7) Front side deposition of a front side passivation layer: and depositing a front passivation layer on the front side of the silicon wafer by adopting an atomic deposition method, wherein the front passivation layer is alumina.
(8) And respectively depositing antireflection film layers on the front surface and the back surface: and respectively depositing an antireflection film layer on the back side and the front side of the silicon wafer by using a chemical vapor deposition method, wherein the antireflection film layer is silicon nitride.
(9) Electrode preparation: and printing silver paste on the front anti-reflection film layer by adopting a screen printing technology, wherein the silver paste is used as a front electrode, the silver paste is printed on the back anti-reflection film layer by adopting the screen printing technology, so as to form a back electrode, the back electrode is positioned in a first area of a passivation contact structure, after sintering, the silver paste on the back is burnt through the anti-reflection film layer, the back electrode is in direct contact with the surface, which is away from the silicon wafer, of the second doped polysilicon layer, corresponding to the first area, the front silver paste is burnt through the front anti-reflection film layer and the passivation layer, and the front electrode is in direct contact with the front of the silicon wafer.
Comparative example 3
A preparation method of a solar cell comprises the following steps:
(1) And cleaning and texturing the N-type silicon wafer.
(2) Boron expansion: and carrying out a front boron diffusion process, wherein the deposition temperature of a boron source is about 900 ℃ and the advancing temperature is about 1000 ℃.
(3) Post-cleaning + backside polishing: the back surface BSG is removed with HF and the back surface of the wafer is polished with KOH.
(4) Depositing a first oxide layer and a first doped polysilicon layer on the back surface: depositing a first oxide layer and a first doped polysilicon layer by adopting a chemical vapor deposition method, wherein the first oxide layer is silicon oxide, the thickness is 1.5nm, the thickness of the first doped polysilicon layer is 50nm, the doping element is phosphorus, and the doping concentration is 3E19cm -3 。
(5) And depositing a second oxide layer and a second doped polysilicon layer on the back surface: depositing a second oxide layer and a second doped polysilicon layer by adopting a chemical vapor deposition method, wherein the second oxide layer is silicon oxide, the thickness is 2nm, the thickness of the second doped polysilicon layer is 100nm, the doping element is phosphorus, and the doping concentration is 5E19cm -3 。
(6) Annealing: annealing at 900 ℃ for 30min.
(7) Front side deposition of a front side passivation layer: and depositing a front passivation layer on the front side of the silicon wafer by adopting an atomic deposition method, wherein the front passivation layer is alumina.
(8) And respectively depositing antireflection film layers on the front surface and the back surface: and respectively depositing an antireflection film layer on the back side and the front side of the silicon wafer by using a chemical vapor deposition method, wherein the antireflection film layer is silicon nitride.
(9) Electrode preparation: and printing silver paste on the front anti-reflection film layer by adopting a screen printing technology, wherein the silver paste is used as a front electrode, the silver paste is printed on the back anti-reflection film layer by adopting the screen printing technology, so as to form a back electrode, the back electrode is positioned in a first area of a passivation contact structure, after sintering, the silver paste on the back is burnt through the anti-reflection film layer, the back electrode is in direct contact with the surface, which is away from the silicon wafer, of the second doped polysilicon layer, corresponding to the first area, the front silver paste is burnt through the front anti-reflection film layer and the passivation layer, and the front electrode is in direct contact with the front of the silicon wafer.
The performances of the solar cells of examples 1 to 3 and comparative examples 1 to 3 were tested and compared with the solar cell of comparative example 1 as a base, and the change value of the solar cell performance compared with comparative example 1 was compared. The test results are shown in Table 1 below.
Test case performance change value = test case performance test value-comparative example 1 performance value.
Table 1 variation in performance compared to comparative example 1
Voc(V) Isc(A) FF(％) Eta(％)
Example 1 0 0.175 -0.2 0.20
Example 2 -0.001 0.170 -0.4 0.10
Comparative example 2 -0.001 0.18 -3.1 -0.70
Example 3 0 0.19 -0.05 0.27
Comparative example 3 -0.001 0.2 -3.4 -0.76
It can be seen that the back surface reflectance of the battery was increased in example 1 and example 3 compared with comparative example 1, so that the short-circuit current of the battery was increased, and the battery efficiency was improved by 0.2% and 0.27%, respectively.
Although example 2 also has the effect of increasing the short-circuit current of the battery by increasing the back reflectivity of the battery compared with example 1, since the laser processing of example 2 uses a larger laser power, the phosphorus atoms of the second doped polysilicon layer are pushed more, resulting in an increase in the penetration ratio of the second oxide layer, so that the concentration of the doping element of the second doped polysilicon layer at a part of the surface located in the first region is reduced more significantly, and the battery efficiency of example 2 is improved by only 0.11% as compared with example 1, which is not achieved by the effect of example 1.
Comparative example 2 and comparative example 3 have higher tunneling resistance due to the step of not performing laser propulsion in comparative example 2 and comparative example 3, although the back reflectivity of the battery is also increased, so that the short-circuit current of the battery is increased, compared to comparative example 1, thereby causing FF to decrease by 3.1%, 3.4%, respectively, and the final battery efficiency to decrease by 0.7%, 0.76%, respectively.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.

Claims (16)

1. The solar cell is characterized by comprising a silicon wafer and a passivation contact structure positioned on the back surface of the silicon wafer;
the passivation contact structure comprises a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer which are sequentially arranged in a direction away from the back surface of the silicon wafer;
the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer respectively comprise a part positioned in a first area and a part positioned in a second area, wherein the first area is an area corresponding to a back electrode, and the second area is other areas except the area corresponding to the back electrode;
the element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region.
2. The solar cell of claim 1, wherein the portion of the second doped polysilicon layer that is located in the first region has an elemental doping concentration that is lower than the elemental doping concentration of the portion of the second doped polysilicon layer that is located in the second region, and wherein the elemental doping concentrations differ by no more than 20% of the elemental doping concentration of the portion of the second doped polysilicon layer that is located in the second region.
3. The solar cell of claim 2, wherein the elemental doping concentration of the portion of the second doped polysilicon layer that is located in the first region and the elemental doping concentration of the portion of the second doped polysilicon layer that is located in the second region are each independently greater than 1E20cm -3 。
4. The solar cell of claim 3, wherein the first doped polysilicon layer satisfies at least one of the following conditions:
(1) The element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region, and the difference of the element doping concentrations is not more than 20% of that of the part of the first doped polysilicon layer located in the second region;
(2) The element doping concentration of the part of the first doped polysilicon layer located in the first region and the part of the first doped polysilicon layer located in the second region are respectively and independently 1E19cm -3 ～1E20cm -3 ；
(3) The thickness of the first doped polysilicon layer is 5 nm-100 nm.
5. The solar cell of claim 1, wherein the second doped polysilicon layer has an elemental doping concentration that is 2-10 times higher in a portion of the first region than in a portion of the second doped polysilicon layer that is in the second region.
6. The solar cell according to claim 5, wherein the element doping concentration of the portion of the second doped polysilicon layer located in the first region and the element doping concentration of the portion of the second doped polysilicon layer located in the second region are each independently 1E19cm -3 ～1E21cm -3 。
7. The solar cell of claim 6, wherein the first doped polysilicon layer satisfies at least one of the following conditions:
(1) The element doping concentration of the part of the first doped polysilicon layer, which is positioned in the first region, is 2-10 times higher than that of the part of the first doped polysilicon layer, which is positioned in the second region;
(2) The element doping concentration of the part of the first doped polysilicon layer located in the first region and the part of the first doped polysilicon layer located in the second region are respectively and independently 1E19cm -3 ～1E20cm -3 ；
(3) The thickness of the first doped polysilicon layer is 5 nm-100 nm.
8. The solar cell of any one of claims 1-7, wherein the first doped polysilicon layer has an elemental doping concentration that is less than or equal to the elemental doping concentration of the second doped polysilicon layer.
9. The solar cell of claim 8, wherein the second doped polysilicon layer has a thickness of 10nm to 200nm.
10. The solar cell of claim 8, wherein the first oxide layer satisfies at least one of the following conditions:
(1) The first oxide layer is made of silicon oxide;
(2) The thickness of the first oxide layer is 1 nm-3 nm.
11. The solar cell of claim 8, wherein the second oxide layer satisfies at least one of the following conditions:
(1) The second oxide layer is made of silicon oxide;
(2) The thickness of the second oxide layer is 1 nm-5 nm.
12. A method of manufacturing a solar cell, comprising the steps of:
forming a passivation contact structure on the back of the silicon wafer;
the passivation contact structure comprises a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer which are sequentially arranged in a direction away from the back surface of the silicon wafer;
the first doped polysilicon layer, the second oxide layer and the second doped polysilicon layer respectively comprise a part positioned in a first area and a part positioned in a second area, wherein the first area is an area corresponding to a back electrode, and the second area is other areas except the area corresponding to the back electrode;
The element doping concentration of the part of the first doped polysilicon layer located in the first region is higher than that of the part of the first doped polysilicon layer located in the second region.
13. The method of fabricating a solar cell according to claim 12, wherein the second doped polysilicon layer has a lower elemental doping concentration in a portion of the first region than in a portion of the second doped polysilicon layer in the second region, and wherein the difference in elemental doping concentrations is no more than 20% of the elemental doping concentration in a portion of the second doped polysilicon layer in the second region, the method comprising the steps of:
sequentially forming a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer on the back surface of the silicon wafer in the direction away from the silicon wafer, and then carrying out annealing treatment;
carrying out laser treatment on the part of the second doped polysilicon layer located in the first region, wherein doping elements of the part of the second doped polysilicon layer located in the first region diffuse to the part of the second oxide layer located in the first region and the part of the first doped polysilicon layer located in the first region, so that the doping concentration of the elements of the part of the first doped polysilicon layer located in the first region is increased, and the doping concentration of the elements of the part of the second doped polysilicon layer located in the first region is reduced;
The conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green light skin second laser or infrared continuous laser; the laser power is 10W-20W.
14. The method of fabricating a solar cell according to claim 12, wherein the second doped polysilicon layer has an element doping concentration 2 to 10 times higher in a portion of the first region than in a portion of the second doped polysilicon layer in the second region, the fabricating of the passivation contact structure comprising the steps of:
sequentially forming a first oxide layer, a first doped polysilicon layer, a second oxide layer and a second doped polysilicon layer on the back surface of the silicon wafer in the direction away from the silicon wafer, and then carrying out annealing treatment;
forming a doped source layer on the second doped polysilicon layer after annealing treatment;
carrying out laser treatment on the part of the doping source layer located in the first region, wherein doping elements of the part of the doping source layer located in the first region diffuse to the part of the second doping polysilicon layer located in the first region, the part of the second oxide layer located in the first region and the part of the first doping polysilicon layer located in the first region, so that the element doping concentration of the part of the first doping polysilicon layer located in the first region and the element doping concentration of the part of the second doping polysilicon layer located in the first region are increased;
The conditions of the laser treatment include: the laser is selected from ultraviolet skin second laser, green nanosecond laser or infrared continuous laser; the laser power is 10W-20W.
15. The method of claim 14, wherein the dopant source layer satisfies at least one of the following conditions:
(1) The doping source layer is PSG or BSG;
(2) The thickness of the doping source layer is 10 nm-100 nm.
16. The method of manufacturing a solar cell according to any one of claims 14 to 15, further comprising the step of, after the step of performing the laser treatment:
and removing the doping source layer.
CN202311321472.2A 2023-10-12 2023-10-12 Solar cell and preparation method thereof Pending CN117253933A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118472055A (en) * 2024-07-09 2024-08-09 浙江爱旭太阳能科技有限公司 Solar cell, passivation contact structure thereof, cell assembly and photovoltaic system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118472055A (en) * 2024-07-09 2024-08-09 浙江爱旭太阳能科技有限公司 Solar cell, passivation contact structure thereof, cell assembly and photovoltaic system

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