CN117410373A - Crystal silicon bottom battery, preparation method thereof and laminated battery - Google Patents
Crystal silicon bottom battery, preparation method thereof and laminated battery Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 34
- 239000010703 silicon Substances 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000013078 crystal Substances 0.000 title description 6
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 80
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 56
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims abstract description 55
- 229920005591 polysilicon Polymers 0.000 claims abstract description 54
- 229910021419 crystalline silicon Inorganic materials 0.000 claims abstract description 45
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000001301 oxygen Substances 0.000 claims abstract description 43
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 43
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 41
- 235000013842 nitrous oxide Nutrition 0.000 claims abstract description 27
- 229910021417 amorphous silicon Inorganic materials 0.000 claims abstract description 25
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910000077 silane Inorganic materials 0.000 claims abstract description 20
- 238000000151 deposition Methods 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 14
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims abstract description 14
- 238000006243 chemical reaction Methods 0.000 claims abstract description 10
- 239000002184 metal Substances 0.000 claims abstract description 10
- 239000007789 gas Substances 0.000 claims abstract description 9
- 238000000137 annealing Methods 0.000 claims abstract description 8
- 238000002425 crystallisation Methods 0.000 claims abstract description 6
- 230000008025 crystallization Effects 0.000 claims abstract description 6
- 238000002161 passivation Methods 0.000 claims description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 239000010453 quartz Substances 0.000 claims description 8
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000005137 deposition process Methods 0.000 abstract description 9
- 238000002834 transmittance Methods 0.000 abstract description 6
- 238000011065 in-situ storage Methods 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical group [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 abstract 1
- 239000010408 film Substances 0.000 description 27
- 230000000052 comparative effect Effects 0.000 description 16
- 239000002245 particle Substances 0.000 description 13
- 230000008021 deposition Effects 0.000 description 6
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 239000012495 reaction gas Substances 0.000 description 5
- 230000003071 parasitic effect Effects 0.000 description 4
- 239000000969 carrier Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910021424 microcrystalline silicon Inorganic materials 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 238000004566 IR spectroscopy Methods 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical group [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000008033 biological extinction Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- SBEQWOXEGHQIMW-UHFFFAOYSA-N silicon Chemical compound [Si].[Si] SBEQWOXEGHQIMW-UHFFFAOYSA-N 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
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- 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
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- H01L31/068—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 the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
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- H10K39/10—Organic photovoltaic [PV] modules; Arrays of single organic PV cells
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Abstract
The invention provides a crystalline silicon bottom battery, a preparation method thereof and a laminated battery, wherein the preparation method comprises the following steps: preparing a silicon wafer, and growing a front ultrathin silicon oxide layer on the front of the silicon wafer; taking laughing gas and silane as reaction gases, and adopting a plasma enhanced chemical vapor deposition method to deposit a p-type oxygen-doped amorphous silicon layer on the surface of the front ultrathin silicon oxide layer; growing a back ultrathin silicon oxide layer on the back of the silicon wafer; depositing an n-type amorphous silicon layer on the surface of the back ultrathin silicon oxide layer; high-temperature crystallization annealing is carried out to form a p-type oxygen-doped polysilicon layer and an n-type polysilicon layer; carrying out hydrotreatment; preparing a front transparent conductive oxide layer; and preparing a back metal electrode. In the invention, oxygen is introduced in situ in the amorphous silicon deposition process, and the p-type oxygen-doped polycrystalline silicon layer and the ultrathin silicon oxide form a front TOPCon structure of the crystalline silicon bottom battery, which is beneficial to improving the long-wave photon transmittance of the TOPCon structure, thereby improving the short-circuit current density of the crystalline silicon bottom battery.
Description
Technical Field
The invention relates to the technical field of solar cells, in particular to a crystalline silicon bottom cell, a preparation method thereof and a laminated cell.
Background
Compared with a single-crystal silicon cell, the multi-junction solar cell has higher sunlight utilization rate, wherein the perovskite/silicon laminated solar cell absorbs short-wavelength light (wavelength of 200-800 nanometers) by perovskite and absorbs long-wavelength light (wavelength of 800-1300 nanometers) by crystal silicon, which has potential advantages in terms of improving efficiency and reducing cost.
Existing crystalline silicon bottom cell structures mainly include Silicon Heterojunction (SHJ) structures and tunnel oxide passivation contact (TOPCon) structures. The SHJ structure consists of multiple layers of amorphous or microcrystalline silicon, while the TOPCon structure consists of a highly doped polysilicon layer and an ultra-thin silicon oxide layer. At present, the SHJ bottom cell using microcrystalline silicon as passivation contact has realized efficient absorption and conversion of long wavelength incident light, but its cost is high. In contrast, TOPCon batteries have achieved the highest photoelectric conversion efficiency within the range of crystalline silicon batteries, while the technology has higher compatibility with existing crystalline silicon battery production lines, facilitating production line upgrades.
At present, the front TOPCon structure of the crystalline silicon bottom cell adopts a polycrystalline silicon material, and a polycrystalline silicon layer has a band gap close to that of monocrystalline silicon, a higher refractive index and a higher extinction coefficient, so that stronger reflection loss and parasitic absorption loss are caused, and the short-circuit current density is reduced, so that the light management of the laminated solar cell is not facilitated.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to solve the technical problems of reducing the reflection loss and parasitic absorption loss of the TOPCon crystalline silicon bottom battery and improving the short-circuit current density.
In order to solve the above problems, a first aspect of the present invention provides a method for preparing a crystalline silicon bottom cell, comprising the steps of:
s1, preparing a silicon wafer, and growing a front ultrathin silicon oxide layer on the front of the silicon wafer;
s2, taking laughing gas and silane as reaction gases, and adopting a plasma enhanced chemical vapor deposition method to deposit a p-type oxygen-doped amorphous silicon layer on the surface of the front ultrathin silicon oxide layer;
s3, growing a back ultrathin silicon oxide layer on the back of the silicon wafer;
s4, depositing an n-type amorphous silicon layer on the surface of the back ultrathin silicon oxide layer;
s5, performing high-temperature crystallization annealing to form a p-type oxygen-doped polysilicon layer and an n-type polysilicon layer;
s6, hydrotreating;
s7, preparing a front transparent conductive oxide layer;
s8, preparing a back metal electrode.
The invention adopts laughing gas as an oxygen source, utilizes a plasma enhanced chemical vapor deposition technology as a preparation means, introduces oxygen element in situ in the amorphous silicon deposition process, and forms the front TOPCon structure of the crystalline silicon bottom battery by the p-type oxygen-doped polycrystalline silicon layer and the ultrathin silicon oxide, thereby being beneficial to improving the long-wave photon transmittance of the TOPCon structure and further improving the short-circuit current density of the crystalline silicon bottom battery.
Further, in the step S2, the flow ratio of silane to laughing gas in the deposition process is 0.5:9.5-9.5:0.5. The flow ratio of silane-laughing gas is regulated, so that the oxygen content can be controlled, and the p-type oxygen-doped polycrystalline silicon film with low refractive index, low reflection intensity and high transmittance is obtained, and the reflection loss and parasitic absorption loss of the battery are reduced.
Further, in S5, the crystallinity of the p-type oxygen doped polysilicon layer is 50 to 100%. The introduced oxygen particles in the p-type oxygen-doped polysilicon layer can be subjected to gap doping or substitution doping, so that the inter-particle distance is increased, the lattice expansion and the stacking compactness are reduced, macroscopic refractive index reduction is shown, and the refractive index of the p-type oxygen-doped polysilicon layer can be adjusted by controlling the crystallinity.
Further, the step S6 specifically includes: placing the crystallized passivation sheet in a quartz boat, feeding the quartz boat into a tube furnace, then introducing water-containing nitrogen into the tube furnace to discharge air, heating to a target temperature, preserving heat for a set time, and taking out the passivation sheet after cooling. The polysilicon oxide reaches a passivation level similar to polysilicon after hydrotreating, maintaining high passivation and low contact resistivity.
The second aspect of the invention provides a crystalline silicon bottom cell, which is prepared by the preparation method, and comprises a transparent conductive oxide layer, a p-type oxygen-doped polycrystalline silicon layer, a front ultrathin silicon oxide layer, a silicon wafer, a back ultrathin silicon oxide layer, an n-type polycrystalline silicon layer and a back metal electrode which are sequentially arranged from front to back.
The invention forms the front TOPCon structure of the crystalline silicon bottom cell by the p-type oxygen-doped polycrystalline silicon and the ultrathin silicon oxide, and compared with the polycrystalline silicon, the p-type oxygen-doped polycrystalline silicon can enable more incident light to enter the monocrystalline silicon and be converted into photo-generated carriers, and can improve the short circuit current density under the condition that the open circuit voltage is almost unchanged.
Further, the oxygen content of the p-type oxygen-doped polysilicon layer is 5-60 at.%.
Further, the boron doping concentration of the p-type oxygen doped polysilicon layer is 1×10 18 ～1×10 22 cm -3 。
Further, the refractive index of the p-type oxygen-doped polysilicon layer is 2-8 within the wavelength range of 300-1400 nm.
Further, the thickness of the p-type oxygen doped polysilicon layer is 5-500 nm, the thickness of the front ultra-thin silicon oxide layer is 0.5-3 nm, and the contact resistivity of the p-type TOPCon structure formed by the p-type oxygen doped polysilicon layer and the front ultra-thin silicon oxide layer is 5-100 mΩ & cm 2 。
The invention introduces oxygen into the polysilicon of the front TOPCO of the crystalline silicon bottom battery, which has at least the following technical effects: the oxygen particles expand the crystal lattice of the polysilicon, so that the p-type oxygen-doped polysilicon has lower refractive index, lower reflectivity and higher transmittance than the p-type polysilicon, thereby enabling the p-type TOPCon structure to allow more incident light to enter the monocrystalline silicon, converting the incident light into photo-generated carriers and improving the short-circuit current density of the battery; oxygen particles have a passivating effect on defects in polysilicon, thus allowing the p-type TOPCon structure to reach a level of passivation after hydrotreatment consistent with that in the absence of oxygen, even if boron activation and diffusion are suppressed to some extent; the introduction of oxygen particles improves the content of B-O pairs in the polysilicon, thereby improving the polarization degree of the polysilicon, improving the surface hydrophilicity and being beneficial to the spreading and covering of polar solution on the surface of the p-type TOPCon structure.
A third aspect of the invention provides a laminated cell comprising a perovskite top cell and a crystalline silicon bottom cell as described above.
The invention takes the TOPCON battery with the front p-type oxygen doped polysilicon as a bottom battery to manufacture the perovskite/crystalline silicon laminated solar cell, and improves the overall short-circuit current density and further improves the efficiency of the laminated battery on the premise of ensuring that the overall open-circuit voltage of the laminated battery is almost unchanged.
In summary, compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, oxygen particles are introduced into polycrystalline silicon on the front surface TOPCO of the crystalline silicon bottom battery, in p-type polycrystalline silicon, crystal lattices are mainly formed by stacking silicon atoms and boron particles, the inter-particle distance is mainly silicon-silicon distance, the stacking compactness is high, the introduced oxygen particles can be subjected to gap doping or substitution doping, so that the inter-particle distance is increased, the crystal lattices expand, the stacking compactness is reduced, macroscopic refractive index is reduced, meanwhile, the boron content in the polycrystalline film is gradually reduced along with the increase of the oxygen content, the reflection of light is reduced, the reflection loss and parasitic absorption loss of the battery are reduced, and the short-circuit current density is improved.
(2) The invention adopts laughing gas as an oxygen source, utilizes a Plasma Enhanced Chemical Vapor Deposition (PECVD) technology as a preparation method, introduces oxygen element in situ in the amorphous silicon deposition process, fully mixes laughing gas molecules with other gases in an in-situ doped reaction cavity, and is dissociated into free particles at the same time with the other gases, and when the laughing gas is changed into solid from plasma, the oxygen particles and other reaction particles are changed at the same time, thereby realizing uniform doping of oxygen element.
(3) The preparation method provided by the invention can realize flexible regulation and control of the thickness, microstructure and oxygen content of the p-type oxygen-doped polysilicon layer, and in-situ introduction of oxygen elements in the amorphous silicon deposition process can reduce process steps, cost and risk, and can realize uniform and controllable doping.
(4) According to the invention, the p-type oxygen-doped polycrystalline silicon is used in the front TOPCon structure of the crystalline silicon bottom cell, so that more incident light can enter the monocrystalline silicon, and the perovskite/crystalline silicon laminated solar cell is manufactured by using the crystalline silicon bottom cell, so that the overall short-circuit current density of the cell is improved, and the efficiency of the laminated cell is further improved.
Drawings
FIG. 1 is a schematic diagram of a crystalline silicon bottom cell in an embodiment of the invention;
FIG. 2 is a graph showing refractive index comparisons of the p-type oxygen doped polysilicon films of examples 1-4 of the present invention and the p-type polysilicon film of comparative example 1;
FIG. 3 is a graph showing the annihilation coefficients of the p-type oxygen doped polysilicon films of examples 1 to 4 of the present invention and the p-type polysilicon film of comparative example 1;
FIG. 4 is a graph showing the comparison of UV-visible-IR spectroscopy for the p-type oxygen doped polysilicon films of examples 1-4 of the present invention and the p-type polysilicon film of comparative example 1;
fig. 5 is a graph comparing the implicit open circuit voltage and single-sided saturation current density of p-type TOPCon of examples 5-8 and comparative example 2 of the present invention;
FIG. 6 is a graph of contact resistivity versus p-type TOPCon for examples 5-8 of the present invention and comparative example 2;
fig. 7 is a graph showing current density-voltage test of the crystalline silicon bottom cell of example 9 and comparative example 3 of the present invention.
Reference numerals illustrate:
the semiconductor device comprises a 1-crystalline silicon substrate, a 2-front ultra-thin silicon oxide layer, a 3-p-type oxygen-doped polycrystalline silicon layer, a 4-transparent conductive oxide layer, a 5-back ultra-thin silicon oxide layer, a 6-n-type polycrystalline silicon layer and a 7-back metal electrode.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It should be noted that the following examples are only for illustrating the implementation method and typical parameters of the present invention, and are not intended to limit the scope of the parameters described in the present invention, so that reasonable variations are introduced and still fall within the scope of the claims of the present invention.
It should be noted that endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and that such range or value should be understood to include values approaching such range or value. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The embodiment of the invention provides a crystalline silicon bottom battery and a preparation method thereof, wherein the preparation method comprises the following steps:
s0, selecting a proper silicon wafer according to requirements, wherein in a specific embodiment, the silicon wafer can be n-type or p-type, the surface structure can be a plane or suede, the thickness of the silicon wafer is 30-1000 mu m, and the silicon wafer is subjected to industrialized standard RCA cleaning.
S1, growing a front ultrathin silicon oxide layer 2 on the front of a silicon wafer, and preferentially adopting a PECVD system for preparation, wherein the preparation can be matched with the subsequent process. In a specific embodiment, the thickness of the front ultra-thin silicon oxide layer 2 is 0.5-3 nm.
S2, depositing a p-type oxygen-doped amorphous silicon layer on the surface of the front ultrathin silicon oxide layer 2 by using a PECVD system, and adopting a plasma enhanced chemical vapor deposition method, wherein laughing gas and silane are used as reaction gases, and the dopant is boron. The flow ratio of silane to laughing gas in the deposition process is 0.5:9.5-9.5:0.5, and the oxygen content in the film can be controlled by adjusting the flow ratio of silane to laughing gas. In a specific embodiment, the thickness of the p-type oxygen-doped amorphous silicon layer is 5-500 nm.
And S3, growing a back ultrathin silicon oxide layer 5 on the back of the silicon wafer, and preferentially adopting a PECVD system for preparation. In a specific embodiment, the thickness of the back ultra-thin silicon oxide layer 5 is 0.5-3 nm.
S4, depositing an n-type amorphous silicon layer on the surface of the back ultrathin silicon oxide layer 5, wherein the reaction gas is silane, and the dopant is phosphorus. In a specific embodiment, the thickness of the n-type amorphous silicon layer is 5-500 nm.
And S5, conveying the deposited silicon wafer into a tube furnace, and performing high-temperature crystallization annealing to form the p-type oxygen-doped polysilicon layer 3 and the n-type polysilicon layer 6.
S6, carrying out hydrotreatment, placing the crystallized passivation sheet in a quartz boat, feeding the quartz boat into a tube furnace, then introducing water-containing nitrogen into the tube furnace to discharge air, heating to a target temperature, preserving heat for a set time, and taking out the passivation sheet after cooling.
And S7, preparing a front transparent conductive oxide layer 4 on the front surface of the passivation sheet.
S8, preparing a back metal electrode 7 on the back of the passivation sheet, wherein the back metal electrode 7 is in the form of a grid line electrode or a full electrode.
The structure of the crystalline silicon bottom battery prepared by the method is shown in fig. 1, and the crystalline silicon bottom battery comprises a transparent conductive oxide layer 4, a p-type oxygen-doped polycrystalline silicon layer 3, a front ultrathin silicon oxide layer 2, a silicon wafer, a back ultrathin silicon oxide layer 5, an n-type polycrystalline silicon layer 6 and a back metal electrode 7 which are sequentially arranged from front to back. The front TOPCon structure of the crystalline silicon bottom cell is composed of p-type oxygen-doped polycrystalline silicon and ultrathin silicon oxide, and compared with the polycrystalline silicon, the p-type oxygen-doped polycrystalline silicon can enable more incident light to enter monocrystalline silicon and be converted into photo-generated carriers, and can improve short circuit current density under the condition that open circuit voltage is almost unchanged.
In a specific embodiment, the oxygen content of the p-type oxygen doped polysilicon layer 3 is 5-60 at%, and the boron doping concentration is 1×10 18 ～1×10 22 cm -3 The TOPCON structure has a refractive index of 2-8,p in the range of 300-1400 nm and a contact resistivity of 5-100 mΩ cm 2 The polysilicon oxide reaches a passivation level similar to that of polysilicon after hydrotreatment, and maintains high passivation and low contact resistanceThe rate.
The perovskite/crystalline silicon laminated solar cell manufactured by the crystalline silicon bottom cell can improve the overall short-circuit current density of the cell, and further improve the efficiency of the laminated cell.
Example 1
Preparing a silicon wafer with a mirror surface polished front surface and a rough back surface, and a quartz plate; the PECVD system is used for depositing p-type amorphous silicon oxide films on the front surface of a silicon wafer and the front surface of a quartz wafer, reaction gases are laughing gas and silane, the flow ratio of the silane to the laughing gas in the deposition process is 4.5:0.5, the thickness of the p-type amorphous silicon oxide film is 100nm, and the process parameters are as follows: the temperature of the carrier plate is 150 ℃, the pressure is 0.5Torr, the silane flow rate is 4.5sccm, the laughing gas flow rate is 0.5sccm, the radio frequency power is 5W, and the deposition time is 300s; then the deposited silicon wafer is sent into a tube furnace for high-temperature crystallization annealing, the gas is high-purity nitrogen, the flow is 1000sccm, the annealing temperature is 920 ℃, and the heat preservation time is 30min, so that a p-type oxygen doped polysilicon film is formed; followed by hydrotreating.
Example 2
This example produced a p-type oxygen doped polysilicon film, which differs from example 1 in that the silane to laughing gas flow ratio during deposition was 4:1.
Example 3
This example produced a p-type oxygen doped polysilicon film, which differed from example 1 in that the silane and laughing gas flow ratio was 3.5:1.5 during deposition.
Example 4
This example produced a p-type oxygen doped polysilicon film, which differs from example 1 in that the silane and laughing gas flow ratio during deposition was 3:2.
Comparative example 1
This comparative example produces a p-type polycrystalline silicon thin film, which differs from example 1 in that the reaction gas used in the deposition process is silane, and the total flow rate of the reaction gas is the same as that in example 1.
The refractive index, annihilation coefficient and ultraviolet-visible-infrared spectroscopic spectra of the polycrystalline silicon oxide films prepared in examples 1 to 4 and the polycrystalline silicon film prepared in comparative example 1 were tested, and the results are shown in fig. 2 to 4. The results show that as the ratio of laughing gas flow rate increases during deposition, the refractive index of the film is obviously reduced, the annihilation coefficient is basically unchanged, the reflectivity is obviously reduced, the absorptivity is basically unchanged, and the transmittance is obviously improved for light with the wavelength of other than 700 nm. As a result, the laughing gas is used as an oxygen source to prepare the p-type oxygen-doped polysilicon, and the long-wave photon transmittance of the TOPCon structure is hopeful to be improved, so that the photo-generated current density of the crystalline silicon bottom battery is improved.
Example 5
Preparing an n-type silicon wafer with two planes; 2nm ultrathin silicon oxide films are grown on the front surface of a silicon wafer by using a PECVD system, and experimental details are as follows: the temperature of the carrier plate is 150 ℃, the pressure is 0.5Torr, the laughing gas flow is 15sccm, the radio frequency power is 5W, and the treatment time is 300s; a p-type amorphous silicon oxide film was deposited on an ultra-thin silicon oxide film using the process of example 1. And then the back surface of the silicon wafer is treated in the same way. The p-type TOPCon is formed by the p-type oxygen-doped polycrystalline silicon film and the ultrathin silicon oxide film after high-temperature annealing.
Example 6
This example prepares a p-type TOPCon, which differs from example 5 in that the preparation process of the p-type amorphous silicon oxide film is the same as that of example 2.
Example 7
This example prepares a p-type TOPCon, which differs from example 5 in that the preparation process of the p-type amorphous silicon oxide film is the same as that of example 3.
Example 8
This example prepares a p-type TOPCon, which differs from example 5 in that the preparation process of the p-type amorphous silicon oxide film is the same as that of example 4.
Comparative example 2
This comparative example produces a p-type TOPCON, which differs from example 5 in that a p-type polysilicon film is used and the production process is the same as that of comparative example 1.
Test examples 5to 8 and comparative example 2 implicit open circuit voltage (iV) of p-type TOPCon structures OC ) Single-sided saturation current density (J) 0,s ) And contact resistivity, the results are shown in fig. 5 and 6. The result shows that as the laughing gas flow rate increases, the implicit open circuit voltage of the p-type TOPCO tends to decrease,the single-sided saturation current density tends to increase, but the variation range is small, which is close to that of the TOPCon case without O. Meanwhile, the contact resistivity is increased and then decreased, and the contact resistivity is almost equal to that of laughing gas when the flow rate ratio of silane to laughing gas is 3:2, which shows that the p-type TOPCO can still keep high passivation and low contact resistivity after O is contained.
Example 9
Preparing an n-type silicon wafer with a plane front surface and a suede back surface; growing a 2nm front ultrathin silicon oxide layer on the front of the silicon wafer by using a PECVD system; depositing a p-type oxygen-doped amorphous silicon layer on the front ultrathin silicon oxide layer by using a PECVD system, wherein reaction gases are laughing gas and silane, the flow ratio of the silane to the laughing gas in the deposition process is 3:2, and the thickness of the p-type oxygen-doped amorphous silicon layer is 100nm; growing a back ultrathin silicon oxide layer with the thickness of 2nm on the back of the silicon wafer; depositing an n-type amorphous silicon layer with the thickness of 100nm on the back ultrathin silicon oxide layer; feeding the deposited silicon wafer into a tube furnace, performing high-temperature crystallization annealing at 920 ℃ for 30min to generate a p-type oxygen-doped polysilicon layer and an n-type polysilicon layer; carrying out hydrotreatment; preparing a front transparent conductive oxide layer; and preparing a back metal electrode to obtain the crystalline silicon bottom battery with the double-sided TOPCon structure.
Comparative example 3
The present comparative example prepared a crystalline silicon bottom cell with a double sided TOPCon structure, which was different from example 9 in that the front side TOPCon was a p-type polysilicon layer, and silane was used as a reaction gas during the deposition of the p-type amorphous silicon thin film, and the total flow rate of the reaction gas was the same as that of example 9.
The current density-voltage curves of the crystalline silicon bottom cells prepared in example 9 and comparative example 3 were tested, and the results are shown in fig. 7. The result shows that after O element is introduced into the TOPCon structure on the front surface of the crystalline silicon bottom battery, the open circuit voltage is almost unchanged, the short circuit current density is obviously improved by about 1.5mA/cm 2 . The p-type oxygen-doped polycrystalline silicon prepared by using laughing gas can improve the photovoltaic response of the crystalline silicon bottom cell, and the p-type oxygen-doped polycrystalline silicon can be applied to perovskite/crystalline silicon laminated solar cells to realize the integral short-circuit current density of the laminated cells, so that the efficiency of the laminated cells is improved.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (10)
1. The preparation method of the crystalline silicon bottom battery is characterized by comprising the following steps of:
s1, preparing a silicon wafer, and growing a front ultrathin silicon oxide layer on the front of the silicon wafer;
s2, taking laughing gas and silane as reaction gases, and adopting a plasma enhanced chemical vapor deposition method to deposit a p-type oxygen-doped amorphous silicon layer on the surface of the front ultrathin silicon oxide layer;
s3, growing a back ultrathin silicon oxide layer on the back of the silicon wafer;
s4, depositing an n-type amorphous silicon layer on the surface of the back ultrathin silicon oxide layer;
s5, performing high-temperature crystallization annealing to form a p-type oxygen-doped polysilicon layer and an n-type polysilicon layer;
s6, hydrotreating;
s7, preparing a front transparent conductive oxide layer;
s8, preparing a back metal electrode.
2. The method according to claim 1, wherein in the step S2, the flow ratio of silane to laughing gas is 0.5:9.5-9.5:0.5.
3. The method of claim 1, wherein the p-type oxygen doped polysilicon layer has a crystallinity of 50 to 100% in S5.
4. The method for preparing a crystalline silicon bottom cell according to claim 1, wherein the step S6 specifically comprises: placing the crystallized passivation sheet in a quartz boat, feeding the quartz boat into a tube furnace, then introducing water-containing nitrogen into the tube furnace to discharge air, heating to a target temperature, preserving heat for a set time, and taking out the passivation sheet after cooling.
5. A crystalline silicon bottom cell, characterized in that it is produced by the production method of any one of claims 1 to 4, and comprises a transparent conductive oxide layer, a p-type oxygen-doped polysilicon layer, a front ultra-thin silicon oxide layer, a silicon wafer, a back ultra-thin silicon oxide layer, an n-type polysilicon layer, and a back metal electrode, which are sequentially arranged from front to back.
6. The crystalline silicon bottom cell of claim 5, wherein the p-type oxygen doped polysilicon layer has an oxygen content of 5to 60at.%.
7. The crystalline silicon bottom cell of claim 6, wherein the p-type oxygen doped polysilicon layer has a boron doping concentration of 1 x 10 18 ～1×10 22 cm -3 。
8. The crystalline silicon bottom cell of claim 7, wherein the p-type oxygen doped polysilicon layer has a refractive index in the range of 2 to 8 at a wavelength of 300 to 1400 nm.
9. The crystalline silicon bottom cell of claim 7, wherein the thickness of the p-type oxygen doped polysilicon layer is 5-500 nm, the thickness of the front ultra-thin silicon oxide layer is 0.5-3 nm, and the contact resistivity of the p-type oxygen doped polysilicon layer and the p-type TOPCon structure formed by the front ultra-thin silicon oxide layer is 5-100 mΩ -cm 2 。
10. A laminated cell comprising a perovskite top cell and a crystalline silicon bottom cell as claimed in any one of claims 5to 9.
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