CN113471314A - Method for preparing selective emitter by using gallium-doped silicon nano slurry - Google Patents
Method for preparing selective emitter by using gallium-doped silicon nano slurry Download PDFInfo
- Publication number
- CN113471314A CN113471314A CN202110494052.9A CN202110494052A CN113471314A CN 113471314 A CN113471314 A CN 113471314A CN 202110494052 A CN202110494052 A CN 202110494052A CN 113471314 A CN113471314 A CN 113471314A
- Authority
- CN
- China
- Prior art keywords
- gallium
- doped silicon
- slurry
- doped
- silicon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 185
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 184
- 239000010703 silicon Substances 0.000 title claims abstract description 184
- 239000002002 slurry Substances 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 76
- 238000009792 diffusion process Methods 0.000 claims abstract description 80
- 239000005543 nano-size silicon particle Substances 0.000 claims abstract description 47
- 229910052751 metal Inorganic materials 0.000 claims abstract description 41
- 239000002184 metal Substances 0.000 claims abstract description 41
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052733 gallium Inorganic materials 0.000 claims abstract description 36
- 230000008569 process Effects 0.000 claims abstract description 29
- 238000001035 drying Methods 0.000 claims abstract description 20
- 238000002360 preparation method Methods 0.000 claims abstract description 19
- 239000002120 nanofilm Substances 0.000 claims abstract description 15
- 238000007650 screen-printing Methods 0.000 claims abstract description 10
- 238000005245 sintering Methods 0.000 claims description 27
- 238000007639 printing Methods 0.000 claims description 22
- 239000011856 silicon-based particle Substances 0.000 claims description 20
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 19
- 229910052796 boron Inorganic materials 0.000 claims description 19
- 238000004140 cleaning Methods 0.000 claims description 18
- 239000002562 thickening agent Substances 0.000 claims description 17
- 239000010408 film Substances 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 239000002270 dispersing agent Substances 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 15
- 239000003960 organic solvent Substances 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 13
- 238000006243 chemical reaction Methods 0.000 claims description 12
- VXQBJTKSVGFQOL-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethyl acetate Chemical compound CCCCOCCOCCOC(C)=O VXQBJTKSVGFQOL-UHFFFAOYSA-N 0.000 claims description 8
- 239000001856 Ethyl cellulose Substances 0.000 claims description 8
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 claims description 8
- 229940028356 diethylene glycol monobutyl ether Drugs 0.000 claims description 8
- 229920001249 ethyl cellulose Polymers 0.000 claims description 8
- 235000019325 ethyl cellulose Nutrition 0.000 claims description 8
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 8
- JCGNDDUYTRNOFT-UHFFFAOYSA-N oxolane-2,4-dione Chemical compound O=C1COC(=O)C1 JCGNDDUYTRNOFT-UHFFFAOYSA-N 0.000 claims description 8
- 238000000498 ball milling Methods 0.000 claims description 7
- 239000005388 borosilicate glass Substances 0.000 claims description 7
- 239000002131 composite material Substances 0.000 claims description 7
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 6
- NWGKJDSIEKMTRX-AAZCQSIUSA-N Sorbitan monooleate Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O NWGKJDSIEKMTRX-AAZCQSIUSA-N 0.000 claims description 6
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 claims description 6
- 229920001400 block copolymer Polymers 0.000 claims description 6
- 229920006217 cellulose acetate butyrate Polymers 0.000 claims description 6
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000151 deposition Methods 0.000 claims description 6
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 6
- 238000002161 passivation Methods 0.000 claims description 6
- -1 polyoxyethylene Polymers 0.000 claims description 6
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 6
- 229940116411 terpineol Drugs 0.000 claims description 6
- AREWWPRVYOZSFA-UHFFFAOYSA-N 2,2-bis(hydroxymethyl)propane-1,3-diol;propane-1,2,3-triol Chemical compound OCC(O)CO.OCC(CO)(CO)CO AREWWPRVYOZSFA-UHFFFAOYSA-N 0.000 claims description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000002202 Polyethylene glycol Substances 0.000 claims description 5
- 239000000853 adhesive Substances 0.000 claims description 5
- 230000001070 adhesive effect Effects 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 5
- 239000002923 metal particle Substances 0.000 claims description 5
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- 229920001223 polyethylene glycol Polymers 0.000 claims description 5
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 5
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 5
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 5
- 238000001308 synthesis method Methods 0.000 claims description 5
- 238000001039 wet etching Methods 0.000 claims description 5
- 239000010409 thin film Substances 0.000 claims description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 2
- 239000005368 silicate glass Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 238000009776 industrial production Methods 0.000 abstract description 5
- 229910021419 crystalline silicon Inorganic materials 0.000 abstract 1
- 235000012431 wafers Nutrition 0.000 description 57
- 230000006798 recombination Effects 0.000 description 11
- 238000005215 recombination Methods 0.000 description 11
- 239000000243 solution Substances 0.000 description 9
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 7
- 238000002156 mixing Methods 0.000 description 7
- 229910052709 silver Inorganic materials 0.000 description 7
- 239000004332 silver Substances 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- 239000004065 semiconductor Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000009835 boiling Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000003685 thermal hair damage Effects 0.000 description 4
- 229910000676 Si alloy Inorganic materials 0.000 description 3
- XNRNVYYTHRPBDD-UHFFFAOYSA-N [Si][Ag] Chemical compound [Si][Ag] XNRNVYYTHRPBDD-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 235000019441 ethanol Nutrition 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 238000001465 metallisation Methods 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- CFOAUMXQOCBWNJ-UHFFFAOYSA-N [B].[Si] Chemical compound [B].[Si] CFOAUMXQOCBWNJ-UHFFFAOYSA-N 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 239000002019 doping agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- XGCTUKUCGUNZDN-UHFFFAOYSA-N [B].O=O Chemical compound [B].O=O XGCTUKUCGUNZDN-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Images
Classifications
-
- 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
- H01L31/0248—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 characterised by their semiconductor bodies
- H01L31/036—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 characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
- H01L31/0392—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 characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
-
- 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
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Photovoltaic Devices (AREA)
Abstract
The invention discloses a method for preparing a selective emitter by utilizing gallium-doped silicon nano slurry, which is characterized in that slurry prepared by utilizing gallium-doped silicon nano particles is used as a doping source on the front surface of a diffused crystalline silicon solar cell, patterns are transferred by adopting screen printing, a gallium-doped silicon nano film is formed after drying, a selective diffusion area of local heavily doped gallium is formed on the front surface of the cell by adopting a laser-assisted diffusion process, and then, the redundant doping source is cleaned and a metal electrode and other subsequent solar cell processes are overprinted, so that the solar cell with the selective emitter is finally obtained. The preparation method of the selective emitter is completely compatible with the existing solar cell production process, does not need to add new equipment, has low production cost and is suitable for industrial production.
Description
Technical Field
The invention relates to the technical field of solar cell preparation, in particular to a method for preparing a selective emitter by using gallium-doped silicon nano slurry.
Background
Among the hot spot problems in the present solar energy research, the tunnel oxide passivation contact (TOPCon) technology has become one of the major research directions of the current industrialized high-efficiency solar cell. The highest conversion efficiency of the N-type TOPCon battery is reported to reach 25.8%. For an N-type battery, a p + emitter region is formed on the front surface of the N-type battery after shallow diffusion, metal contact is formed after screen printing of a metal electrode and drying and sintering, and due to the fact that the metal electrode is in direct contact with a silicon substrate, metal contact recombination damage is formed, current carriers are seriously recombined, and dark saturation current density (J) reflected in the contact region is achieved0,metal) The average particle size is high, and the general range is 1000-2000 fA/cm2This also makes it difficult to further improve the battery performance. With the rapidly increasing market demand for efficient batteries and high power components, it is important to reduce the recombination of the metal-semiconductor contact regions. The front surface selective emitter can form local deep junction doping, can effectively reduce the probability of introducing impurity energy level into a forbidden band by metal, and simultaneously reduces contact resistance and minority carrier recombination rate.
The preparation of the TOPCon battery selective emitter reported at present is mainly carried out by adopting a boron diffusion mode, and a boron doping process mainly adopts the following steps: 1) a method utilizing laser chemistry; 2) adopting liquid or gaseous boron source for high-temperature diffusion; 3) depositing boron-doped silicon oxide film. However, the normal thermal diffusion of boron is completed at a high temperature of over 1000 ℃, and the local temperature of the laser chemical method is also extremely high, so that the internal structure of the crystal is changed, secondary defects are generated, the quality of a silicon wafer is greatly influenced, the performance of the solar cell is reduced, and the boron doping process is not suitable for modern industrial production all the time. At present, a boron-silicon glass layer formed in the front surface diffusion process is mainly utilized for laser-assisted diffusion in the preparation of the TOPCon battery selective emitter, but the boron element doping concentration in the boron-silicon glass layer is relatively low, so that high-concentration doping is difficult to form, and in the boron diffusion process, due to the existence of a boron-oxygen complex, light attenuation is easy to cause. The mode of most directly eliminating the light attenuation uses gallium element to replace boron as a dopant, so in order to obtain higher doping effect and further improve the performance of the battery, the diffuser containing the gallium doping source is more beneficial to industrial application.
Disclosure of Invention
The invention discloses a method for preparing a selective emitter by using gallium-doped silicon nano slurry, which has low cost, is compatible with the existing process, can be industrially produced and has high productivity, and solves the problems of high cost, special production equipment and high-temperature thermal damage caused by boron diffusion in the prior art so as to restrict the performance improvement of a solar cell.
The invention provides a method for preparing a selective emitter by using gallium-doped silicon nano slurry, which comprises the following steps:
the first step is as follows: performing texturing, cleaning and surface diffusion on the N-type silicon wafer to obtain a silicon wafer in a previous working procedure;
the second step is that: printing the doping source on the front surface of the front procedure silicon wafer obtained in the first step by taking the gallium-doped silicon nano slurry as the doping source, and drying to obtain a gallium-doped silicon nano film;
the third step: performing local diffusion on the surface of the silicon wafer by adopting a laser-assisted diffusion method;
the fourth step: cleaning redundant gallium-doped silicon thin films on the surface of the silicon wafer; placing the diffused silicon wafer in a wet etching machine, and removing the borosilicate glass layer; depositing passivation, antireflection film and oxide layer on the front and back surfaces;
the fifth step: and finally, overprinting the metal slurry above the local area of the heavily doped gallium, and forming ohmic contact after sintering to obtain the selective emitter.
Furthermore, in the first step, the N-type silicon wafer is a monocrystalline silicon wafer or a polycrystalline silicon wafer used for the solar cell, and the surface diffusion is boron diffusion or gallium diffusion to form a pn junction.
Furthermore, the doping source in the gallium-doped silicon nano slurry in the second step is gallium-doped silicon nano particles, the size range of the gallium-doped particles is 5-500 nm, and the doping concentration range of gallium elements in the gallium-doped particles is 1 multiplied by 1017～1×1021atoms/cm3Gallium-doped silicon nano-slurryThe gallium-doped silicon nano-film is formed by mixing gallium-doped silicon nano-particles and an organic carrier consisting of an organic solvent, a thickening agent and a dispersing agent, wherein the mass fraction range of the gallium-doped silicon nano-particles is 5-50%, the gallium-doped silicon nano-paste is used for printing the gallium-doped silicon nano-paste on the front surface of a silicon wafer in the previous process in a screen printing mode, the drying temperature is 200-350 ℃, the drying time is 10-30 s, the thickness range of the gallium-doped silicon nano-film obtained after drying is 0.5-5 mu m, and the gallium-doped silicon nano-film is used as a diffusion source and adhered to the surface of the silicon wafer.
Further, the gallium-doped silicon nano slurry is printed on the front surface of the silicon wafer in the previous process in a screen printing mode, and the printing pattern is a straight line, a line segment or a point.
Furthermore, the gallium-doped silicon nanoparticles refer to silicon particles which are uniformly gallium-doped, the doped silicon nanoparticles are prepared by adopting a pulse discharge method, a plasma reaction synthesis method or a ball-milling composite preparation method, the silicon purity is more than or equal to 95%, the size is normally distributed, and the concentration is more than 90%.
Further, the formula of the gallium-doped silicon nano slurry in percentage by mass is as follows: 5-50% of gallium-doped silicon nanoparticles, 50-80% of organic solvent, 1-10% of dispersant and 2-10% of thickener, wherein the viscosity of the slurry is 10-100 Pa.s (Brookfield HBT 10rpm 25 ℃), and the thickness range of the slurry after printing is 2-10 μm; the dispersant is one or a mixture of more of sodium dodecyl benzene sulfonate, span 80, polyethylene glycol, polyvinylpyrrolidone, polyoxyethylene block copolymer, glycerol pentaerythritol and polyacrylamide; the organic solvent is one or a mixture of several of diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol; the thickener is one or mixture of ethyl cellulose and cellulose acetate butyrate.
Further, the laser power density range of the laser-assisted diffusion in the third step is 2-8J/cm3The diameter of a light spot is 20-50 mu m, the scanning speed is 1-16 m/s, the repetition frequency is 100-1000 KHz, the laser wavelength is 532-1032 nm, and the local doping concentration range of the surface of the silicon wafer after laser diffusion is 1 multiplied by 1018～5×1020atoms/cm3The diffusion depth is 0.2 to 5 μm.
Further, the excess silicon slurry on the surface of the silicon wafer diffused in the fourth step is cleaned by absolute ethyl alcohol, and the cleaned silicon slurry and the borosilicate glass or gallium-silicate glass layer formed after the surface diffusion in the first step are cleaned by sodium hydroxide or potassium hydroxide solution with the mass fraction of 1-10%.
Furthermore, in the fifth step, the metal electrode on the fingerprint does not exceed the area occupied by the gallium-doped silicon film, the sintering process adopts rapid sintering, metal particles in the metal slurry and silicon particles are fully fused during high-temperature sintering, so that the metal electrode and a silicon wafer form good ohmic contact and excellent adhesive force, the contact resistance is reduced, the transmission of photoproduction current is ensured, the sintering temperature range is 600-900 ℃, the peak temperature heat preservation time is 1-10 s, and the metal slurry and the doped region form good ohmic contact to form a selective emitter.
Has the advantages that:
compared with the prior art, the method for preparing the selective emitter by using the gallium-doped silicon nano slurry has the following advantages:
1. low cost, compatibility with the prior process, industrial production and high productivity;
2. the preparation method is mainly characterized in that gallium-doped silicon nanoparticles are prepared into slurry, and then the slurry is printed on the surface of a battery and is subjected to laser-assisted diffusion, wherein the printing is finished by adopting a screen printing method without additionally adding special equipment and adopting conventional equipment;
3. the traditional boron diffusion process usually adopts a liquid or gaseous boron source, and the boron doping layer is obtained by diffusion at a high temperature of more than 1000 ℃, but the method has adverse effect on the performance of the battery, and has high difficulty and high cost. The method takes the gallium-doped silicon nano slurry as a doping source, utilizes laser to carry out auxiliary diffusion, has simple steps and low cost, is compatible with the prior process, and can be used for industrial production;
4. compared with boron as a doping source, the gallium doping source in the gallium-doped silicon nano slurry is more beneficial to reducing light attenuation and improving the photoelectric conversion efficiency of the battery. In addition, the silicon nano-particle has the characteristic of low melting point, the damage to a silicon wafer can be reduced by using laser-assisted doping, and meanwhile, in the process that a metal electrode and silicon form metal-semiconductor contact, a silicon nano-film supplements silicon elements, so that the diffusion of metal to a silicon substrate is reduced, and the performance of a battery can be improved;
5. in the production process, a gallium-doped silicon ingot or silicon rod can be used as a raw material, silicon particles are self-doped with gallium instead of adding a gallium source in slurry, so that local doping can be realized without complex processes and expensive equipment, the beneficial effects of prolonging the service life of minority carriers of a solar cell, reducing the surface recombination efficiency of the cell, reducing the contact resistance and the like are achieved, and the photoelectric conversion efficiency of the cell is finally improved.
6. The printed pattern can be simply and conveniently controlled by adopting a printing mode, and common equipment is adopted, so that the method is simple, convenient and feasible. In addition, the printing mode can be adopted to integrally form the printing pattern on the surface of the silicon wafer at one time, and then the subsequent steps of integral drying, diffusion and the like are carried out, thereby being beneficial to saving the processing time. The gallium-doped silicon nano film after laser diffusion can utilize the characteristics of low melting point, easy diffusion and the like of silicon nano particles, and combines the excellent attenuation resistance of gallium element, thereby not only reducing the production cost, but also improving the performance of the battery.
7. The organic carrier in the slurry has simple components, few selected organic solvents, low boiling point and easy preparation, and has the advantages that: firstly, impurities cannot be introduced in the later sintering process, and secondly, silver particles and silicon particles in the slurry are fully fused, so that the diffusion of metal in a silicon substrate is reduced, the recombination rate of a metal-semiconductor contact area is effectively reduced, and the performance of the battery is improved.
8. The gallium-doped silicon nanoparticles refer to silicon particles which are uniformly doped with gallium, the doped silicon nanoparticles can be prepared by adopting a pulse discharge method, a plasma reaction synthesis method, a ball-milling composite preparation method and the like, the preparation yield is high by adopting the pulse discharge and ball-milling composite method, the cost is low, and the industrial production is most easily realized. Preparation of boron doped silicon by pulse discharge methodThe technological process of the ball is elaborated in the invention patents of Wanwein, Zhang and flood donation, namely, the preparation method and the device (patent publication No. CN102744477A) of the nano-particles of the shock wave assisted ultrashort pulse discharge. The gallium-doped silicon nanoparticles can be prepared by referring to similar processing methods, the doping concentration of gallium can be adjusted according to the concentration of a raw material silicon ingot or a silicon rod, or the gallium-doped silicon nanoparticles can be prepared by adding a doping agent into undoped silicon particles in a compounding manner, and the concentration of gallium atoms can be 1 x 1017～1×1021atoms/cm3To select between. The preparation of gallium-doped silicon nanoparticles with different sizes can be realized by adopting different processing parameters, the size of the silicon nanoparticles is preferably 5-500 nm, the purity of silicon is more than or equal to 95%, the size of the silicon nanoparticles is normally distributed, and the concentration is more than 90%.
Drawings
Fig. 1 is a schematic diagram of the selective emitter prepared by using gallium-doped silicon nano-slurry provided in the present application.
Detailed Description
The present invention will be described below with reference to specific examples. It should be noted that the following examples are only for illustrating the present invention and do not represent the scope of the present invention, and that other people having the following examples may make insubstantial modifications and adjustments according to the teachings of the present invention.
Example 1
The embodiment provides a method for preparing a selective emitter by using gallium-doped silicon nano slurry, wherein the gallium-doped silicon nano slurry is formed by mixing gallium-doped nano silicon particles and an organic carrier. The selective emitter is prepared by adopting gallium-doped silicon nano slurry as a raw material, printing a pattern by using a screen printer and performing auxiliary diffusion by using laser. The method comprises the following specific steps:
the first step is as follows: selecting a phosphorus-doped N-type monocrystalline silicon wafer with the resistivity of 0.5-2 omega-cm, placing the phosphorus-doped N-type monocrystalline silicon wafer into a texturing groove, and performing surface texturing to form a textured structure in a sodium hydroxide solution with the specific gravity of 5-15% at the temperature of 75-80 ℃;
the second step is that: cleaning the surface of the silicon wafer with a chemical solution, wherein the solution is a mixed solution of hydrofluoric acid and hydrochloric acid, the cleaning time is 2Min, and the temperature is 20-25 ℃;
the third step: after cleaning, placing the silicon wafer in a diffusion furnace, and performing boron diffusion at 1050-1100 ℃ for 30Min to form a pn junction to obtain a silicon wafer in the previous process, wherein the square resistance after diffusion is 100 omega;
the fourth step: and (3) printing the doping source on the front surface of the front-process silicon wafer obtained in the third step by taking the gallium-doped silicon nano slurry as the doping source, wherein the doping source in the gallium-doped silicon nano slurry is from gallium-doped silicon nano particles, the size range of the gallium-doped particles is 5-500 nm, and the doping concentration range of gallium elements in the gallium-doped particles is 1 multiplied by 1017～1×1021atoms/cm3The gallium-doped silicon nano slurry is formed by mixing gallium-doped silicon nano particles and an organic carrier consisting of an organic solvent, a thickening agent and a dispersing agent, wherein the mass fraction range of the gallium-doped silicon nano particles is 20%, the gallium-doped silicon nano slurry is printed on the front surface of a silicon wafer in the previous working procedure in a screen printing mode, the drying temperature is 250 ℃, the drying time is 30s, the thickness range of a gallium-doped silicon nano film obtained after drying is 3-4 mu m, the gallium-doped silicon nano film is made to be adhered to the surface of the silicon wafer as a diffusion source, when a printed pattern is a linear array, the line width is 30 mu m, the line spacing is 1000 mu m, and the printing thickness is 10 mu m; the organic carrier in the slurry has simple components, low boiling point and easy preparation, reduces the diffusion of metal in a silicon substrate, effectively reduces the recombination rate of a metal-semiconductor contact area, and improves the performance of a battery; the gallium-doped silicon nanoparticles are prepared by uniformly doping gallium into silicon particles by adopting a pulse discharge method, a plasma reaction synthesis method or a ball-milling composite preparation method, the silicon purity is more than or equal to 95%, the size is normally distributed, and the concentration is more than 90%; the formula of the gallium-doped silicon nano slurry comprises the following components in percentage by mass: 5-50% of gallium-doped silicon nanoparticles, 50-80% of organic solvent, 1-10% of dispersant and 2-10% of thickener, wherein the viscosity of the slurry is 10-100 Pa.s (Brookfield HBT 10rpm 25 ℃), and the thickness range of the slurry after printing is 2-10 μm; the dispersant adopts sodium dodecyl benzene sulfonate and span80. One or a mixture of more of polyethylene glycol, polyvinylpyrrolidone, polyoxyethylene block copolymer, glycerol pentaerythritol and polyacrylamide; the organic solvent is one or a mixture of several of diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol; the thickening agent is one or a mixture of two of ethyl cellulose and cellulose acetate butyrate;
the fifth step: auxiliary diffusion is carried out by laser, and the laser energy density is 3J/cm3The diameter of a light spot is 40 mu m, the scanning speed is 12m/s, the repetition frequency is 800KHz, the laser wavelength is 532nm, and the maximum gallium doping concentration after laser diffusion is 3.5 multiplied by 1019atoms/cm3The diffusion depth is 1 mu m, and because of the characteristic of low melting point of the silicon nanoparticles, the silicon nanoparticles can be melted by adopting smaller energy, thereby being more beneficial to the diffusion of gallium elements to a matrix and reducing the thermal damage of a silicon wafer as much as possible;
and a sixth step: cleaning with alcohol to remove the non-irradiated area of the laser and remove the residual redundant silicon film;
the seventh step: placing the diffused silicon wafer in a wet etching machine, and removing the borosilicate glass layer;
eighth step: depositing passivation, antireflection film and oxide layer on the front and back surfaces;
the ninth step: front and back surface metallization process, wherein front silver paste is overprinted above a heavily doped gallium local area, the silver paste is in contact with a silicon body after being sintered, ohmic contact is formed after sintering, a selective emitter is obtained, and a deposited silicon film in the laser-assisted diffusion process can promote the formation of silver-silicon alloy; the printed metal electrode does not exceed the area occupied by the gallium-doped silicon film, the sintering process adopts rapid sintering, metal particles and silicon particles in metal slurry are fully fused during high-temperature sintering, so that the metal electrode and a silicon wafer form good ohmic contact and excellent adhesive force, the contact resistance is reduced, the transmission of photoproduction current is guaranteed, the sintering temperature is 780 ℃, the peak temperature heat preservation time is 1-10 s, and the metal slurry and a doped region form good ohmic contact to form a selective emitter.
Performing performance test on the prepared silicon wafer, and galliumLocally selective emitter formed by doping silicon nano slurry as diffusion source enables dark saturation current density (J) of front surface0,metal) Reduce the concentration to 50 to 100fA/cm2And the surface recombination rate is obviously reduced, 1000 silicon wafers are selected in the experiment, the battery piece prepared by the scheme of the invention is used as an experimental piece, and the battery piece without the selective emitter prepared by the experimental process is used as a standard piece.
Table 1 comparison of cell parameters for example 1 with standard cell plates
In this embodiment, the parameters of the gallium-doped silicon nanoparticles used as the doping source are as follows: the size range of the silicon particles is 10-400 nm, the size is concentrated in 300nm, the concentration is more than 90%, and the doping concentration range of gallium elements in the silicon particles is 1 multiplied by 1020～5×1020atoms/cm3. The gallium-doped silicon nano slurry contains 20% of solid content, the organic carrier is diethylene glycol monobutyl ether (mass fraction of 35%), diethylene glycol monobutyl ether acetate (mass fraction of 30%), the thickening agent is ethyl cellulose (mass fraction of 10%), the dispersing agent is sodium dodecyl benzene sulfonate (mass fraction of 5%) and the viscosity is 45-50 Pa.s.
In the embodiment, the metal slurry is a product produced in mass production, no new equipment is introduced in the process, and the gallium-doped silicon nano slurry and laser-assisted diffusion are utilized to carry out local gallium doping, so that the dark saturation current density and the contact resistance are reduced, and the photoelectric conversion efficiency of the cell is improved.
Example 2
The embodiment provides a method for preparing a selective emitter by using gallium-doped silicon nano slurry, wherein the gallium-doped silicon nano slurry is formed by mixing gallium-doped nano silicon particles and an organic carrier. The selective emitter is prepared by adopting gallium-doped silicon nano slurry as a raw material, printing a pattern by using a screen printer and performing auxiliary diffusion by using laser. The method comprises the following specific steps:
the first step is as follows: selecting a phosphorus-doped N-type monocrystalline silicon wafer with the resistivity of 0.5-2 omega-cm, placing the phosphorus-doped N-type monocrystalline silicon wafer into a texturing groove, and performing surface texturing to form a textured structure in a sodium hydroxide solution with the specific gravity of 5-15% at the temperature of 75-80 ℃;
the second step is that: cleaning the surface of the silicon wafer with a chemical solution, wherein the solution is a mixed solution of hydrofluoric acid and hydrochloric acid, the cleaning time is 2Min, and the temperature is 20-25 ℃;
the third step: after cleaning, placing the silicon wafer in a diffusion furnace, and performing boron diffusion at 950-1200 ℃ for about 5-30 Min, wherein the rear resistance after diffusion is 60-100 omega, so as to form a pn junction to obtain a silicon wafer in the previous process;
the fourth step: and (3) printing the doping source on the front surface of the front-process silicon wafer obtained in the third step by taking the gallium-doped silicon nano slurry as the doping source, wherein the doping source in the gallium-doped silicon nano slurry is from gallium-doped silicon nano particles, the size range of the gallium-doped particles is 5-400 nm, and the doping concentration range of gallium elements in the gallium-doped particles is 1 multiplied by 1017～1×1021atoms/cm3The gallium-doped silicon nano slurry is formed by mixing gallium-doped silicon nano particles and an organic carrier consisting of an organic solvent, a thickening agent and a dispersing agent, wherein the mass fraction range of the gallium-doped silicon nano particles is 5-50%, the gallium-doped silicon nano slurry is printed on the front surface of a silicon wafer in the previous working procedure in a screen printing mode, the drying temperature is 300 ℃, the drying time is 30s, the thickness range of a gallium-doped silicon nano film obtained after drying is 0.5-5 mu m, the gallium-doped silicon nano film is made to adhere to the surface of the silicon wafer as a diffusion source, when a printed pattern is a linear array, the line width is 40 mu m, the line spacing is 1000 mu m, and the printing thickness is 15 mu m; the organic carrier in the slurry has simple components, low boiling point and easy preparation, reduces the diffusion of metal in a silicon substrate, effectively reduces the recombination rate of a metal-semiconductor contact area, and improves the performance of a battery; the gallium-doped silicon nanoparticles are prepared by uniformly doping gallium into silicon particles by adopting a pulse discharge method, a plasma reaction synthesis method or a ball-milling composite preparation method, the silicon purity is more than or equal to 95%, the size is normally distributed, and the concentration is more than 90%; the formula of the gallium-doped silicon nano slurry comprises the following components in percentage by mass: gallium-doped silicon nanoparticles40% of particles, 50% of organic solvent, 1-10% of dispersant and 2% -10% of thickener, wherein the viscosity of the slurry is 10-100 Pa.s (Brookfield HBT 10rpm 25 ℃), and the thickness range of the printed slurry is 2-10 μm; the dispersant is one or a mixture of more of sodium dodecyl benzene sulfonate, span 80, polyethylene glycol, polyvinylpyrrolidone, polyoxyethylene block copolymer, glycerol pentaerythritol and polyacrylamide; the organic solvent is one or a mixture of several of diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol; the thickening agent is one or a mixture of two of ethyl cellulose and cellulose acetate butyrate;
the fifth step: the laser is adopted for auxiliary diffusion, and the laser energy density is 6.5J/cm3The diameter of a light spot is 40 mu m, the scanning speed is 8m/s, the repetition frequency is 500KHz, the laser wavelength is 532nm, and the maximum gallium doping concentration after laser diffusion is 6.5 multiplied by 1019atoms/cm3The diffusion depth is 1.5 mu m, and because of the characteristic of low melting point of the silicon nanoparticles, the silicon nanoparticles can be melted by adopting smaller energy, thereby being more beneficial to the diffusion of gallium elements to a matrix and reducing the thermal damage of a silicon wafer as much as possible;
and a sixth step: cleaning with alcohol to remove the non-irradiated area of the laser and remove the residual redundant silicon film;
the seventh step: placing the diffused silicon wafer in a wet etching machine, and removing the borosilicate glass layer;
eighth step: depositing passivation, antireflection film, oxide layer and other procedures on the front and back surfaces;
the ninth step: front and back surface metallization, wherein front silver paste is overprinted above the heavily doped gallium local area, the silver paste is in contact with a silicon body after sintering, and a silicon film deposited in the laser-assisted diffusion process can promote the formation of silver-silicon alloy; the printed metal electrode does not exceed the area occupied by the gallium-doped silicon film, the sintering process adopts rapid sintering, metal particles and silicon particles in metal slurry are fully fused during high-temperature sintering, so that the metal electrode and a silicon wafer form good ohmic contact and excellent adhesive force, the contact resistance is reduced, the transmission of photoproduction current is guaranteed, the sintering temperature is 820 ℃, the peak temperature heat preservation time is 1-10 s, and the metal slurry and a doped area are guaranteed to form good ohmic contact to form a selective emitter.
Performing performance test on the prepared silicon wafer, and using the gallium-doped silicon nano slurry as a local selective emitter formed by a diffusion source to enable the front surface to have dark saturation current density (J)0,metal) Reduce the concentration to 20 to 60fA/cm2And the surface recombination rate is obviously reduced, 1000 silicon wafers are selected in the experiment, the battery piece prepared by the scheme of the invention is used as an experimental piece, and the battery piece without the selective emitter prepared by the experimental process is used as a standard piece.
Table 2 comparison of cell parameters of example 2 with standard cell plates
In this embodiment, the parameters of the gallium-doped silicon nanoparticles used as the doping source are as follows: the size range of the silicon particles is 50-500 nm, the size is concentrated in 250nm, the concentration is more than 90%, and the doping concentration range of gallium elements in the silicon particles is 5 multiplied by 1020～1×1021atoms/cm3. The gallium-doped silicon nano slurry contains 30% of solid content, the organic carrier comprises diethylene glycol monobutyl ether (mass fraction of 30%), diethylene glycol monobutyl ether acetate (mass fraction of 30%), the thickening agent comprises ethyl cellulose (mass fraction of 5%), span 80 (mass fraction of 5%) and viscosity of 60-65 Pa.s.
In the embodiment, the metal slurry is a product produced in mass production, no new equipment is introduced in the process, and the gallium-doped silicon nano slurry and laser-assisted diffusion are utilized to carry out local gallium doping, so that the dark saturation current density and the contact resistance are reduced, and the photoelectric conversion efficiency of the cell is improved.
Example 3
The embodiment provides a method for preparing a selective emitter by using gallium-doped silicon nano slurry, wherein the gallium-doped silicon nano slurry is formed by mixing gallium-doped nano silicon particles and an organic carrier. The selective emitter is prepared by adopting gallium-doped silicon nano slurry as a raw material, printing a pattern by using a screen printer and performing auxiliary diffusion by using laser. The method comprises the following specific steps:
the first step is as follows: selecting a phosphorus-doped N-type monocrystalline silicon wafer with the resistivity of 0.5-2 omega-cm, placing the phosphorus-doped N-type monocrystalline silicon wafer into a texturing groove, and performing surface texturing to form a textured structure in a sodium hydroxide solution with the specific gravity of 5-15% at the temperature of 75-80 ℃;
the second step is that: cleaning the surface of the silicon wafer with a chemical solution, wherein the solution is a mixed solution of hydrofluoric acid and hydrochloric acid, the cleaning time is 2Min, and the temperature is 20-25 ℃;
the third step: after cleaning, placing the silicon wafer in a diffusion furnace, and performing boron diffusion at 950-1200 ℃ for about 5-30 Min, wherein the rear resistance after diffusion is 60-100 omega, so as to form a pn junction to obtain a silicon wafer in the previous process;
the fourth step: and (3) printing the doping source on the front surface of the front-process silicon wafer obtained in the third step by taking the gallium-doped silicon nano slurry as the doping source, wherein the doping source in the gallium-doped silicon nano slurry is from gallium-doped silicon nano particles, the size range of the gallium-doped particles is 5-500 nm, and the doping concentration range of gallium elements in the gallium-doped particles is 1 multiplied by 1017～1×1021atoms/cm3The gallium-doped silicon nano slurry is formed by mixing gallium-doped silicon nano particles and an organic carrier consisting of an organic solvent, a thickening agent and a dispersing agent, wherein the mass fraction range of the gallium-doped silicon nano particles is 5-50%, the gallium-doped silicon nano slurry is used for printing the gallium-doped silicon nano slurry on the front surface of a silicon wafer in the previous working procedure in a screen printing mode, the drying temperature is 200 ℃, the drying time is 20s, the thickness range of a gallium-doped silicon nano film obtained after drying is 0.5-5 mu m, the gallium-doped silicon nano film is used as a diffusion source to be adhered to the surface of the silicon wafer, when a printed pattern is a linear array, the line width is 30 mu m, the line spacing is 1000 mu m, and the printing thickness is 10 mu m; the organic carrier in the slurry has simple components, low boiling point and easy preparation, reduces the diffusion of metal in a silicon substrate, effectively reduces the recombination rate of a metal-semiconductor contact area, and improves the performance of a battery; the gallium-doped silicon nanoparticles refer to silicon particles which are uniformly gallium-doped, and the doped silicon nanoparticles are synthesized by adopting a pulse discharge method and a plasma reaction or ball-milling composite methodThe preparation method is characterized in that the purity of silicon is more than or equal to 95 percent, the size of the silicon is normally distributed, and the concentration ratio is more than 90 percent; the formula of the gallium-doped silicon nano slurry comprises the following components in percentage by mass: 5-50% of gallium-doped silicon nanoparticles, 50-80% of organic solvent, 1-10% of dispersant and 2-10% of thickener, wherein the viscosity of the slurry is 10-100 Pa.s (Brookfield HBT 10rpm 25 ℃), and the thickness range of the slurry after printing is 2-10 μm; the dispersant is one or a mixture of more of sodium dodecyl benzene sulfonate, span 80, polyethylene glycol, polyvinylpyrrolidone, polyoxyethylene block copolymer, glycerol pentaerythritol and polyacrylamide; the organic solvent is one or a mixture of several of diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol; the thickening agent is one or a mixture of two of ethyl cellulose and cellulose acetate butyrate;
the fifth step: the laser is adopted for auxiliary diffusion, and the laser energy density is 2.5J/cm3The diameter of a light spot is 40 mu m, the scanning speed is 16m/s, the repetition frequency is 200KHz, the laser wavelength is 1064nm, and the maximum gallium doping concentration after laser diffusion is 5 multiplied by 1019atoms/cm3The diffusion depth is 0.5 mu m, and because of the characteristic of low melting point of the silicon nanoparticles, the silicon nanoparticles can be melted by adopting smaller energy, thereby being more beneficial to the diffusion of gallium elements to a matrix and reducing the thermal damage of the silicon wafer as much as possible;
and a sixth step: cleaning with alcohol to remove the non-irradiated area of the laser and remove the residual redundant silicon slurry;
the seventh step: placing the diffused silicon wafer in a wet etching machine, and removing the borosilicate glass layer;
eighth step: depositing passivation, antireflection film, oxide layer and other procedures on the front and back surfaces;
the ninth step: front and back surface metallization, wherein front silver paste is overprinted above the heavily doped gallium local area, the silver paste is in contact with a silicon body after sintering, and a silicon film deposited in the laser-assisted diffusion process can promote the formation of silver-silicon alloy; the printed metal electrode does not exceed the area occupied by the gallium-doped silicon film, the sintering process adopts rapid sintering, metal particles and silicon particles in metal slurry are fully fused during high-temperature sintering, so that the metal electrode and a silicon wafer form good ohmic contact and excellent adhesive force, the contact resistance is reduced, the transmission of photoproduction current is guaranteed, the sintering temperature is 800 ℃, the peak temperature heat preservation time is 1-10 s, the metal slurry and a doped area are guaranteed to form good ohmic contact, and a selective emitter is formed.
Performing performance test on the prepared silicon wafer, and using the gallium-doped silicon nano slurry as a local selective emitter formed by a diffusion source to enable the front surface to have dark saturation current density (J)0,metal) Reduce the concentration to 10 to 40fA/cm2And the surface recombination rate is obviously reduced, 1000 silicon wafers are selected in the experiment, the battery piece prepared by the scheme of the invention is used as an experimental piece, and the battery piece without the selective emitter prepared by the experimental process is used as a standard piece.
In this embodiment, the parameters of the gallium-doped silicon nanoparticles used as the doping source are as follows: the size range of the silicon particles is 5-300 nm, the size is concentrated at 150nm, the concentration is more than 90%, and the doping concentration range of gallium element in the silicon particles is 5 multiplied by 1020～1×1021atoms/cm3. The gallium-doped silicon nano slurry contains 10% of solid content, the organic carrier is diethylene glycol monobutyl ether (mass fraction of 30%), diethylene glycol monobutyl ether acetate (mass fraction of 30%), terpineol (mass fraction of 20%), the thickening agent is ethyl cellulose (mass fraction of 6%), cellulose acetate butyrate (mass fraction of 2%), the polyoxyethylene block copolymer (mass fraction of 2%) and the viscosity of 30-35 Pa & s.
Table 3 comparison of cell parameters for example 3 with standard cell plates
In the embodiment, the metal slurry is a product produced in mass production, no new equipment is introduced in the process, and the gallium-doped silicon nano slurry and laser-assisted diffusion are utilized to carry out local gallium doping, so that the dark saturation current density and the contact resistance are reduced, and the photoelectric conversion efficiency of the cell is improved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A method for preparing a selective emitter by using gallium-doped silicon nano slurry is characterized by comprising the following steps:
the first step is as follows: performing texturing, cleaning and surface diffusion on the N-type silicon wafer to obtain a silicon wafer in a previous working procedure;
the second step is that: printing the doping source on the front surface of the front procedure silicon wafer obtained in the first step by taking the gallium-doped silicon nano slurry as the doping source, and drying to obtain a gallium-doped silicon thin film;
the third step: performing local diffusion on the surface of the silicon wafer by adopting a laser-assisted diffusion method;
the fourth step: cleaning redundant gallium-doped silicon thin films on the surface of the silicon wafer; placing the diffused silicon wafer in a wet etching machine, and removing the borosilicate glass layer; depositing passivation, antireflection film and oxide layer on the front and back surfaces;
the fifth step: and finally, overprinting the metal slurry above the local area of the heavily doped gallium, and forming ohmic contact after sintering to obtain the selective emitter.
2. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 1, wherein: in the first step, the N-type silicon wafer is a monocrystalline silicon wafer or a polycrystalline silicon wafer used by the solar cell, and the surface diffusion is boron diffusion or gallium diffusion to form a pn junction.
3. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 1, wherein: in the second step, the doping source in the gallium-doped silicon nano slurry comes from gallium-doped silicon nano particles, the size range of the gallium-doped particles is 5-500 nm, and the doping concentration range of gallium elements in the gallium-doped particles is 1 multiplied by 1017～1×1021 atoms/cm3The gallium-doped silicon nano slurry is prepared from galliumThe gallium-doped silicon nano-slurry is printed on the front surface of a silicon wafer in the previous process in a screen printing mode, the drying temperature is 200-350 ℃, the drying time is 10-30 s, the thickness range of the gallium-doped silicon nano-film obtained after drying is 0.5-5 mu m, and the gallium-doped silicon nano-film is made to adhere to the surface of the silicon wafer as a diffusion source.
4. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 3, wherein: the gallium-doped silicon nano slurry is printed on the front surface of the silicon wafer in the previous process in a screen printing mode, and the printed pattern is a straight line, a line segment or a point.
5. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 3, wherein: the gallium-doped silicon nanoparticles are prepared by uniformly doping gallium into silicon particles by adopting a pulse discharge method, a plasma reaction synthesis method or a ball-milling composite preparation method, the silicon purity is more than or equal to 95%, the size is normally distributed, and the concentration is more than 90%.
6. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 3, wherein: the formula of the gallium-doped silicon nano slurry comprises the following components in percentage by mass: 5% -50% of gallium-doped silicon nanoparticles, 50% -80% of organic solvent, 1% -10% of dispersing agent and 2% -10% of thickening agent, wherein the viscosity of the slurry is 10-100 Pa.s (Brookfield HBT 10rpm 25 ℃), and the thickness range of the slurry after printing is 2-10 mu m; the organic solvent is one or a mixture of several of diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and terpineol; the thickening agent is one or a mixture of two of ethyl cellulose and cellulose acetate butyrate; the dispersing agent is one or a mixture of several of sodium dodecyl benzene sulfonate, span 80, polyethylene glycol, polyvinylpyrrolidone, polyoxyethylene block copolymer, glycerol pentaerythritol and polyacrylamide.
7. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 1, wherein: the laser power density range of the laser-assisted diffusion in the third step is 2-8J/cm3The diameter of a light spot is 20-50 mu m, the scanning speed is 1-16 m/s, the repetition frequency is 100-1000 KHz, the laser wavelength is 532-1032 nm, and the local doping concentration range of the surface of the silicon wafer after laser diffusion is 1 x 1018～5×1020atoms/cm3And the diffusion depth is 0.2-5 mu m.
8. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to any one of claims 1 to 8, wherein: and cleaning the redundant silicon slurry on the surface of the silicon wafer diffused in the fourth step by using absolute ethyl alcohol, and cleaning the cleaned redundant silicon slurry and the borosilicate glass or gallium-silicate glass layer formed after the surface diffusion in the first step by using a sodium hydroxide or potassium hydroxide solution with the mass fraction of 1-10%.
9. The method for preparing a selective emitter using gallium-doped silicon nano-slurry according to claim 1, wherein: in the fifth step, overprinting is to ensure that the metal electrode on the fingerprint does not exceed the area occupied by the gallium-doped silicon film, the sintering process adopts rapid sintering, metal particles in the metal slurry and silicon particles are fully fused during high-temperature sintering, so that the metal electrode and a silicon wafer form good ohmic contact and excellent adhesive force, the contact resistance is reduced, the transmission of photoproduction current is ensured, the sintering temperature range is 600-900 ℃, the peak temperature heat preservation time is 1-10 s, and the metal slurry and a doped area form good ohmic contact to form a selective emitter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494052.9A CN113471314A (en) | 2021-05-07 | 2021-05-07 | Method for preparing selective emitter by using gallium-doped silicon nano slurry |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494052.9A CN113471314A (en) | 2021-05-07 | 2021-05-07 | Method for preparing selective emitter by using gallium-doped silicon nano slurry |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113471314A true CN113471314A (en) | 2021-10-01 |
Family
ID=77870644
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110494052.9A Pending CN113471314A (en) | 2021-05-07 | 2021-05-07 | Method for preparing selective emitter by using gallium-doped silicon nano slurry |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113471314A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016189424A (en) * | 2015-03-30 | 2016-11-04 | 帝人株式会社 | Semiconductor device manufacturing method |
| CN106448806A (en) * | 2016-10-26 | 2017-02-22 | 盐城工学院 | Conductive paste for PERC solar cell, preparation method and application thereof |
| CN107112381A (en) * | 2014-12-30 | 2017-08-29 | 默克专利股份有限公司 | The method of doped semiconductor |
| CN111739985A (en) * | 2020-08-21 | 2020-10-02 | 浙江晶科能源有限公司 | Solar cell and preparation method of selective emitter thereof |
-
2021
- 2021-05-07 CN CN202110494052.9A patent/CN113471314A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107112381A (en) * | 2014-12-30 | 2017-08-29 | 默克专利股份有限公司 | The method of doped semiconductor |
| JP2016189424A (en) * | 2015-03-30 | 2016-11-04 | 帝人株式会社 | Semiconductor device manufacturing method |
| CN106448806A (en) * | 2016-10-26 | 2017-02-22 | 盐城工学院 | Conductive paste for PERC solar cell, preparation method and application thereof |
| CN111739985A (en) * | 2020-08-21 | 2020-10-02 | 浙江晶科能源有限公司 | Solar cell and preparation method of selective emitter thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110265497B (en) | N-type crystalline silicon solar cell with selective emitter and preparation method thereof | |
| CN109494261A (en) | Silica-based solar cell and preparation method, photovoltaic module | |
| CN1719621A (en) | Silicon solar battery structure and making method | |
| CN112490304A (en) | Preparation method of high-efficiency solar cell | |
| CN102593262A (en) | Diffusion method for solace cell with polycrystalline silicon selective emitter | |
| CN103500774B (en) | A kind of method utilizing P-type silicon ball to prepare local back surface field as boron source | |
| CN104617164A (en) | Nano silicon boron slurry and method for preparing solar cell with the same | |
| CN209183556U (en) | Silica-based solar cell and photovoltaic module | |
| Yadav et al. | c-Si solar cells formed from spin-on phosphoric acid and boric acid | |
| CN116741871A (en) | Method for manufacturing N-type TOPCON battery with boron-extended SE structure | |
| CN116565039A (en) | Selective boron doping structure and preparation method and application thereof | |
| EP4060752A1 (en) | Solar cell stack passivation structure and preparation method therefor | |
| CN111106188A (en) | N-type battery, preparation method of selective emitter of N-type battery and N-type battery | |
| EP4379816A1 (en) | Solar cell and manufacturing method therefor | |
| CN106784049B (en) | Preparation method of local doped crystalline silicon solar cell and prepared cell | |
| CN113471422A (en) | Method for preparing gallium-doped nano silicon particles by using silicon waste | |
| CN114649424B (en) | Electrode structure of crystalline silicon solar cell | |
| CN114937706B (en) | Laminated passivation film for crystalline silicon solar cell and preparation method thereof | |
| CN113471314A (en) | Method for preparing selective emitter by using gallium-doped silicon nano slurry | |
| CN116053353A (en) | Preparation method of boron doped selective emitter and N-type crystalline silicon solar cell | |
| CN111755563B (en) | P-type monocrystalline silicon boron back-field double-sided battery and preparation method thereof | |
| CN114023636A (en) | Manufacturing method of efficient N-type TOPCon battery with boron diffusion SE structure | |
| Ng et al. | Development of p+/n+ polysilicon tunnel junctions compatible for industrial screen printing | |
| KR20130069678A (en) | Solar cell of doping layer fabrication method using solid phase epitaxy | |
| CN108133974A (en) | A kind of polycrystalline mixes gallium double-side solar cell and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |