WO2019237561A1 - 一种背接触太阳能电池及其制备方法 - Google Patents

一种背接触太阳能电池及其制备方法 Download PDF

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WO2019237561A1
WO2019237561A1 PCT/CN2018/107643 CN2018107643W WO2019237561A1 WO 2019237561 A1 WO2019237561 A1 WO 2019237561A1 CN 2018107643 W CN2018107643 W CN 2018107643W WO 2019237561 A1 WO2019237561 A1 WO 2019237561A1
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layer
film layer
forming
thin film
area
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PCT/CN2018/107643
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French (fr)
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舒欣
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君泰创新（北京）科技有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • 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
    • H01L31/0682—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 back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction 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
    • Y02E10/547—Monocrystalline silicon PV cells
    • 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

Definitions

  • This application relates to, but is not limited to, the field of solar cells, and in particular, but not limited to, a back-contact solar cell and a method for manufacturing the same.
  • Back-contact solar cells are batteries in which both the P region (positive electrode) and the N region (negative electrode) are placed on the back (non-light-receiving surface) of the cell. And because the P and N regions are located on the same horizontal plane and are close to each other, the P and N regions are easy to be electrically conductive, which leads to the decrease of the battery's open circuit voltage, short-circuit current, and filling factor, thereby affecting the improvement of battery energy conversion efficiency. .
  • the back surface pattern In order to prepare an efficient solar cell, a back surface pattern with good insulation performance needs to be prepared between the P region and the N region.
  • the back surface pattern is mostly prepared by a photolithography method and a laser method.
  • a method for preparing a back-contact solar cell includes:
  • first functional region and the second functional region have different conductivity types.
  • a back-contact solar cell is also provided, and the back-contact solar cell is prepared by the above-mentioned preparation method.
  • a back-contact solar cell is also provided.
  • the back-contact solar cell includes:
  • a substrate the back surface of which has protrusions and grooves
  • FIG. 1 is a flowchart of a method for preparing a back-contact solar cell according to an embodiment of the present application
  • FIG. 2a to FIG. 2j are schematic diagrams of a process for preparing a back contact solar cell according to an embodiment of the present application
  • FIG. 3 is a schematic structural diagram of a back contact solar cell prepared in an embodiment of the present application.
  • a crystalline silicon substrate 2. a first intrinsic silicon thin film layer; 3. a first doped silicon thin film layer; 4. a first transparent conductive layer; 5. a protective layer; 6. a second intrinsic silicon Thin film layer; 7. second doped silicon thin film layer; 8. second transparent conductive layer; 9. passivation layer; 10. antireflection layer; 11. first metal electrode; 12. second metal electrode.
  • the inventor of the present application has found that the use of photolithography technology to prepare the back surface pattern requires multiple photolithography, resulting in a complicated process, and the photolithography process is expensive, which is not conducive to the production of cheap solar cells. It is easy to damage the silicon body and the surface, and additional processes are required to remove the damage. There are also problems of complicated processes.
  • a method for preparing a back-contact solar cell includes: forming a first functional region on a back surface of a substrate, and the first functional region includes a reserved region and a removed region. Forming a protective layer on the reserved region; removing the removing region and forming a trench on the back surface of the substrate; forming a second functional region within the trench; removing the protective layer; wherein, The first functional area is different from the conductive type of the second functional area.
  • the preparation method further includes: after removing the protective layer, forming a first electrode on a first functional region of the reserved region; and forming a first electrode on the second functional region. Two electrodes.
  • forming a protective layer on the reserved area includes: forming the protective layer on the reserved area by a screen printing process; and / or flattening a cover plate on the reserved area. To form the protective layer.
  • the forming the protective layer on the reserved area by a screen printing process includes: laying a screen printing screen on the first functional area, the screen printing screen Plate covering the removal area, exposing the reserved area; printing a barrier paste on the first functional area through the screen printing screen; drying and curing the barrier paste; removing the screen Printing a screen plate to form the protective layer on the reserved area; optionally, the blocking paste includes at least one of a polymer material and paraffin.
  • removing the removing area and forming a trench on the back surface of the substrate includes: removing the removing area by an etching process to expose the back surface of the substrate; The bottom surface is etched with the trench.
  • the depth of the trench is 0.5 ⁇ m to 5 ⁇ m.
  • the removing the protective layer includes removing the protective layer by at least one of physical peeling and chemical etching.
  • the preparation method further includes: forming a passivation layer or an anti-reflection layer on the front surface of the substrate, or forming a passivation layer and an anti-reflection layer.
  • the preparation method further includes: before forming the passivation layer or the anti-reflection layer, texturing the front surface of the substrate.
  • the reserved area and the removed area are alternately arranged.
  • the forming a first functional region on the back surface of the substrate includes: forming a first intrinsic silicon thin film layer on the back surface of the substrate; and on the first intrinsic silicon thin film layer Forming a first doped silicon thin film layer; forming a first transparent conductive layer on the first doped silicon thin film layer; the first intrinsic silicon thin film layer, the first doped silicon thin film layer, and the first A transparent conductive layer forms the first functional region.
  • the forming a second functional region in the trench includes: forming a second intrinsic silicon thin film layer in the trench; on the second intrinsic silicon thin film layer Forming a second doped silicon thin film layer; forming a second transparent conductive layer on the second doped silicon thin film layer; the second intrinsic silicon thin film layer, the second doped silicon thin film layer, and the first Two transparent conductive layers form the second functional region.
  • a back-contact solar cell is also provided, and the back-contact solar cell is prepared by the above-mentioned preparation method.
  • a back-contact solar cell includes: a substrate, a back surface of the substrate having protrusions and grooves; The P-type functional area and the N-type functional area provided in the groove, or the N-type functional area provided on the protrusion and the P-type functional area provided in the groove; The P-type functional area and the N-type functional area have a height difference, the height difference is 0.5 ⁇ m to 5 ⁇ m; and an insulating layer disposed on a sidewall of the trench, the insulating layer connecting the P-type functional area It is insulated from the N-type functional area.
  • the P-type functional region includes an intrinsic silicon thin film layer, a p-type doped silicon thin film layer, and a transparent conductive layer, the intrinsic silicon thin film layer, and the p-type doped silicon
  • the thin film layer and the transparent conductive layer are sequentially disposed on the protrusion or the groove, and the transparent conductive layer is provided with an electrode
  • the N-type functional region includes an intrinsic silicon thin film layer and an n-type doped layer.
  • a hetero-silicon thin film layer and a transparent conductive layer, the intrinsic silicon thin film layer, the n-type doped silicon thin film layer, and the transparent conductive layer are sequentially disposed in the trench or on the protrusion, and the transparent An electrode is provided on the conductive layer.
  • the back-contact solar cell further includes a passivation layer or an anti-reflection layer, or a passivation layer and an anti-reflection layer disposed on a front surface of the substrate.
  • the front side of the substrate is pyramid-shaped.
  • An embodiment of the present application provides a method for preparing a back-contact solar cell. As shown in FIG. 1, the method includes:
  • Step S1 forming a first functional region on the back surface of the substrate, the first functional region including a reserved region and a removed region;
  • Step S2 forming a protective layer on the reserved area
  • Step S3 removing the removal area, and forming a trench on the back surface of the substrate;
  • Step S4 forming a second functional region in the trench, the first functional region and the second functional region having different conductivity types;
  • Step S5. Remove the protective layer.
  • a first functional area is first formed on the back surface of the substrate, and then a mask is formed using a protective layer to protect the remaining area of the first functional area; a trench is formed on the back surface of the substrate corresponding to the unmasked removed area And forming a second functional region in the trench; finally removing the mask (protective layer) to prepare a back-contact solar cell.
  • the portion where the groove is not formed on the back surface of the substrate is a bump corresponding to the groove
  • the remaining region corresponds to the raised portion on the back surface of the substrate
  • the removal region corresponds to the groove portion on the back surface of the substrate.
  • the substrate may be a crystalline silicon substrate.
  • the preparation method provided in the embodiment of the present application only needs to use a mask to prepare a back surface pattern with insulation properties, which can avoid the use of photolithography and laser methods, and has a simple process and low cost.
  • a back-contact solar cell having a height difference between the first functional area and the second functional area can be obtained, and the height difference avoids contact between the first functional area and the second functional area, forming good insulation, and avoiding It reduces the open-circuit voltage, short-circuit current, and filling factor caused by the conduction of the two, thereby improving the energy conversion efficiency of the battery.
  • the conductive type of the first functional region is different from that of the second functional region
  • the first functional region can be a positive electrode or a negative electrode
  • the second functional region is a negative electrode or a positive electrode.
  • step S1 forming the first functional region on the back surface of the crystalline silicon substrate 1 may include the following steps:
  • Step S101 forming a first intrinsic silicon thin film layer 2 on the back surface of the crystalline silicon substrate 1;
  • Step S102 forming a first doped silicon thin film layer 3 on the first intrinsic silicon thin film layer 2;
  • Step S103 forming a first transparent conductive layer 4 on the first doped silicon thin film layer 3;
  • the first intrinsic silicon thin film layer 2, the first doped silicon thin film layer 3, and the first transparent conductive layer 4 form a first functional region.
  • first functional region is the N region as an example
  • a first functional region is formed on the back surface of the crystalline silicon substrate 1.
  • N regions having different stacked structures may be formed according to actual conditions.
  • forming the N region on the back surface of the crystalline silicon substrate 1 may include the following steps:
  • Step S101 forming a first intrinsic silicon thin film layer 2 on the back surface of the crystalline silicon substrate 1;
  • Step S102 forming an n-type doped silicon thin film layer on the first intrinsic silicon thin film layer 2;
  • Step S103 forming a first transparent conductive layer 4 on the n-type doped silicon thin film layer
  • the first intrinsic silicon thin film layer 2, the n-type doped silicon thin film layer, and the first transparent conductive layer 4 form a first functional region.
  • the first functional region may also be set as a P region.
  • the first doped silicon thin film layer 3 is a p-type doped silicon thin film layer.
  • the first functional region may be formed on the back surface of the crystalline silicon substrate 1 by a deposition method.
  • a plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD) method may be used to sequentially deposit and deposit a first intrinsic silicon thin film layer 2 and a first doped silicon on the back surface of the crystalline silicon substrate 1.
  • the thin film layer 3 can be deposited on the first doped silicon thin film layer 3 by a physical vapor deposition method (Physical Vapor Deposition, PVD).
  • the substrate may be a crystalline silicon substrate 1, for example, an n-type single crystal silicon wafer or a p-type single crystal silicon wafer may be selected.
  • an n-type single crystal silicon wafer may be selected as the substrate, and the n-type single crystal silicon wafer may have a thickness of 100 ⁇ m to 200 ⁇ m and a resistivity of 1 ⁇ cm to 10 ⁇ cm.
  • the first intrinsic silicon thin film layer 2 may be an amorphous silicon film (a-Si: H) or an amorphous silicon-oxygen alloy film (a-SiO x : H), and the first intrinsic silicon film
  • the thickness of the thin film layer 2 may be 1 nm to 10 nm.
  • the first doped silicon thin film layer 3 may be an n-type doped silicon thin film layer, and the n-type doped silicon thin film layer may be a phosphorus-doped amorphous silicon layer, for example, it may be a-Si: H And any one of a-SiO x : H, c-SiO x : H, etc., and the thickness of the n-type doped silicon thin film layer can be 1 nm to 10 nm.
  • the first transparent conductive layer 4 may be a transparent conductive oxide layer, such as a tin-doped indium oxide transparent conductive film (ITO), a tungsten-doped indium oxide transparent conductive film (indium titanium oxide) , IWO), aluminum-doped zinc oxide transparent conductive film (AZO) or cesium-doped indium oxide transparent conductive film (ICO), etc., and can make the first transparent
  • the thickness of the conductive layer 4 is 10 nm to 200 nm.
  • step S1 in order to make the first functional area include a reserved area and a removed area, a reserved area and a removed area may be divided on the first functional area on the back surface of the substrate.
  • the reserved area and the removed area may be alternately disposed on the first functional area.
  • the reserved region is the N or P region of the back contact solar cell that is finally formed, and correspondingly, the removed region is the P or N region of the back contact solar cell that is finally formed.
  • the shapes of the retention area and the removal area may be set according to actual needs.
  • the retention area and the removal area can be set to be elongated bars arranged alternately, for example, rectangular.
  • the embodiment of the present application does not strictly limit the area ratio of the retention area and the removal area. In actual preparation, it can be determined through simulation and optimization according to needs.
  • the area ratio of the adjacent P and N regions can be set to 3: 1 by setting the reserved region and the removed region.
  • the substrate before depositing the first functional area, can be cleaned by RCA standard to remove the damage layer (SDR) to remove the organic matter, particles and metal ions on the substrate surface, thereby forming a clean Substrate surface.
  • SDR damage layer
  • the protective layer is used to protect the reserved area to avoid damage to subsequent processes. Forming a protective layer on the reserved area can be achieved in a number of ways.
  • a protective layer 5 may be formed on the reserved area by a screen printing process, and may include the following steps:
  • Step S201 laying the screen printing screen in the first functional area, the screen printing screen covering the removal area, exposing the reserved area;
  • Step S202 Printing the barrier paste on the first functional area through a screen printing screen
  • Step S203 drying and curing the barrier slurry
  • Step S204 Remove the screen printing screen to form a protective layer 5 on the reserved area.
  • the barrier slurry may be at least one of a polymer material, a paraffin material, and the like.
  • the drying slurry can be dried using a drying oven.
  • the screen printing process has the advantage of high alignment accuracy.
  • the formed protective layer 5 can accurately cover the reserved area and meet the design requirements.
  • the screen printing method is used to form the protective layer 5.
  • the barrier paste used is inexpensive and can reduce production costs.
  • the protective layer 5 may also be formed using a cover plate.
  • the cover plate can be tiled on the reserved area to form the protective layer 5.
  • fasteners can be used to fasten the cover plate on the reserved area, so that the cover plate is in close contact with the reserved area, forming protection of the reserved area, and avoiding damage to the reserved area by subsequent processes.
  • step S3 an etching process can be used to remove the removal area, and a trench can be formed on the back surface of the substrate.
  • step S3 may include the following steps:
  • Step S301 removing the removal area by an etching process, and exposing the back surface of the crystalline silicon substrate 1;
  • Step S302 a trench is etched on the back surface of the crystalline silicon substrate 1.
  • step S301 an etching (such as wet chemical etching) process can be used to remove the removal area, and the back surface of the crystalline silicon substrate 1 is exposed.
  • a wet chemical etching method may be adopted to etch a trench on the back surface of the crystalline silicon substrate 1 by controlling the etching time, and finally a height difference is formed on the back surface of the crystalline silicon substrate 1.
  • This height difference can form a good insulation between the first functional area and the second functional area that is finally formed.
  • a shallow trench may not achieve the insulation effect, and an excessively deep trench may cause crystalline silicon.
  • the substrate 1 is destroyed, and therefore, the depth of the trench can be 0.5 ⁇ m to 5 ⁇ m.
  • the first transparent conductive layer 4 in the removal area may be first etched by using a first etching solution (such as HF, HCl, etc.), as shown in FIG. 2c;
  • a first etching solution such as HF, HCl, etc.
  • a second etching solution such as KOH, tetramethylammonium hydroxide (TMAH), etc.
  • TMAH tetramethylammonium hydroxide
  • a third etching solution (such as KOH, TMAH, etc.) is used to control the chemical etching time to etch a trench on the back surface of the crystalline silicon substrate 1, as shown in FIG. 2e.
  • the wet chemical etching method has the advantages of simple process, low cost, convenient control, and no damage.
  • the wet chemical etching method can be used to remove amorphous silicon very conveniently and prepare the required back surface pattern without bringing additional damage.
  • forming a second functional region in the trench with a conductivity type different from that of the first functional region may include the following steps:
  • Step S401 forming a second intrinsic silicon thin film layer 6 on the inner surface of the trench;
  • Step S402 forming a second doped silicon thin film layer 7 on the second intrinsic silicon thin film layer 6;
  • Step S403 forming a second transparent conductive layer 8 on the second doped silicon thin film layer 7;
  • the second intrinsic silicon thin film layer 6, the second doped silicon thin film layer 7, and the second transparent conductive layer 8 form a second functional region.
  • the second functional region when the first functional region is an N region, the second functional region may be a P region.
  • forming the second functional region in the trench may include the following steps:
  • Step S401 forming a second intrinsic silicon thin film layer 6 in the trench
  • Step S402 forming a p-type doped silicon thin film layer on the second intrinsic silicon thin film layer 6;
  • Step S403 forming a second transparent conductive layer 8 on the p-type doped silicon-based thin film layer
  • the second intrinsic silicon thin film layer 6, the p-type doped silicon thin film layer, and the second transparent conductive layer 8 form a second functional region.
  • the second functional region is an N region
  • the second doped silicon thin film layer 7 may be an n-type doped silicon thin film layer.
  • the second functional region may be formed in the trench by a deposition method.
  • a second intrinsic silicon thin film layer 6 and a second doped silicon thin film layer 7 may be sequentially deposited on the back surface of the crystalline silicon substrate 1 by using a PECVD deposition method.
  • a second transparent conductive layer 8 is deposited on the hetero-silicon thin film layer 7.
  • the second functional region formed on the back surface of the crystalline silicon substrate 1 can cover the trench and can also cover the protective layer 5.
  • the second intrinsic silicon thin film layer 6 may be an amorphous silicon film (a-Si: H) or an amorphous silicon-oxide alloy film (a-SiO x : H), and the second intrinsic silicon film
  • the thickness of the thin film layer 6 may be 1 nm to 10 nm.
  • the second doped silicon thin film layer 7 may be a p-type doped silicon thin film layer, for example, may be a boron-doped amorphous silicon layer, for example, may be a-Si: H, a-SiO x : H, c-SiO x : H, etc., and the thickness of the p-type doped silicon thin film layer can be from 1 nm to 10 nm.
  • the second transparent conductive layer 8 may be a transparent conductive oxide layer, such as any one of an ITO film, an IWO film, an AZO film, or an ICO film, and the second transparent conductive layer 8 may be The thickness is from 10 nm to 200 nm.
  • the substrate before the second functional area is deposited, the substrate may also be subjected to RCA standard cleaning and the remaining chemical solution is removed to form a clean substrate surface.
  • the protective layer 5 can be removed by at least one of physical peeling and chemical etching, and the protective layer 5 can be peeled off at the same time.
  • the second functional region (the second intrinsic silicon thin film layer 6, the second doped silicon thin film layer 7, and the second transparent conductive layer 8) exposes the first functional region.
  • a barrier slurry removal solution for example, a hydrofluoric acid HF solution, etc.
  • a hydrofluoric acid HF solution may be used to remove the protective layer 5 formed by the barrier slurry, and the second substrate on the protective layer 5 is peeled off.
  • the silicon thin film layer 6, the second doped silicon thin film layer 7, and the second transparent conductive layer 8 are applied, so that the back surface of the crystalline silicon substrate 1 presents the first functional region and the second functional region simultaneously.
  • a second intrinsic silicon thin film layer 6 can be formed on the sidewall of the trench at the same time (as shown in FIG. 2g).
  • the protective layer 5 is removed by using the above method, the second intrinsic silicon thin film layer 6 formed on the sidewall of the trench may be retained, and the second intrinsic silicon thin film layer 6 may form between the first functional region and the second functional region. Another insulation.
  • the front surface of the crystalline silicon substrate 1 is the light-receiving surface of the cell.
  • the above preparation method may further include:
  • Step S6 A passivation layer or an anti-reflection layer is formed on the front surface of the substrate, or a passivation layer and an anti-reflection layer are formed.
  • the front surface of the substrate can also be cleaned by RCA standard, and the remaining chemical solution can be removed to form a clean substrate surface.
  • a PECVD deposition method may be used to deposit an intrinsic amorphous silicon layer on the front surface of the crystalline silicon substrate 1 to form a passivation layer 9.
  • the thickness of the intrinsic amorphous silicon layer may be 1nm to 10nm;
  • a PVD deposition method can also be used to deposit a transparent conductive layer (such as a transparent conductive oxide (TCO) film) on the passivation layer 9 to form an anti-reflection layer 10 with a thickness of the transparent conductive layer It can be from 10 nm to 200 nm.
  • TCO transparent conductive oxide
  • a phosphorus-doped amorphous silicon layer may also be formed on the front surface of the crystalline silicon substrate 1.
  • the thickness of the phosphorus-doped amorphous silicon layer may be 1 nm to 10 nm.
  • a front surface field (FSF) is formed on the front surface of the crystalline silicon substrate 1.
  • FSF front surface field
  • the phosphorus-doped amorphous silicon layer can be located between the passivation layer 9 and the antireflection layer 10.
  • the preparation method may further include: texturing the front surface of the crystalline silicon substrate 1.
  • the front surface of the crystalline silicon substrate 1 may be textured in an alkaline solution (KOH or TMAH) (at this time, the first transparent conductive layer 4 and the second transparent conductive layer 8 on the back surface may Graphics for protection).
  • KOH or TMAH alkaline solution
  • a pyramid shape can be formed on the front surface of the crystalline silicon substrate 1 to reduce light reflection loss on the surface of the battery.
  • the above preparation method may further include:
  • Step S7 forming a first electrode on the first functional area of the reserved area; and forming a second electrode on the second functional area.
  • the first electrode may be a first metal electrode 11, the second electrode may be a second metal electrode 12, and the first metal electrode 11 and the second metal electrode 12 may be a silver grid. And copper electrodes.
  • electrodes such as a silver grid
  • first transparent conductive layer 4 and the second transparent conductive layer 8 respectively by a screen printing process
  • first transparent conductive layer 4 and the second transparent conductive layer may be respectively plated by electroplating.
  • An electrode, such as a copper electrode, is prepared on the layer 8.
  • first functional area is the N area and the second functional area is the P area
  • first functional area is the P area and the second functional area is "N zone” is equivalent.
  • the embodiment of the present application further provides a back-contact solar cell, which is prepared by the above-mentioned preparation method.
  • the back-contact solar cell prepared by the above preparation method provided in the embodiment of the present application has a height difference between the first functional region and the second functional region formed on the substrate, and the height difference avoids the first functional region and the second functional region.
  • the contact between the functional areas forms a good insulation, which avoids the reduction of the open circuit voltage, short circuit current, and fill factor caused by the conduction of the two, thereby improving the energy conversion efficiency of the battery.
  • the solar cell prepared by the above method provided in the embodiment of the present application includes:
  • a crystalline silicon substrate 1, a back surface of the crystalline silicon substrate 1 is provided with a first surface and a second surface having a height difference;
  • a first intrinsic silicon thin film layer 2 a first doped silicon thin film layer 3, a first transparent conductive layer 4, and a first metal electrode 11 disposed in this order on a first side;
  • a third surface is further provided on the back surface of the crystalline silicon substrate 1, and the third surface is located between the first and second surfaces and is perpendicular to the first and second surfaces; an insulating layer is provided on the third surface. ;
  • a passivation layer 9 or an anti-reflection layer 10, or a passivation layer 9 and an anti-reflection layer 10 is further provided on the front surface of the crystalline silicon substrate 1.
  • An embodiment of the present application further provides a back-contact solar cell.
  • the back-contact solar cell includes: a substrate, a back surface of the substrate having protrusions and grooves; and a P-type functional area provided on the protrusions. And an N-type functional region provided in the groove, or an N-type functional region provided on the protrusion and a P-type functional region provided in the groove; the P-type functional region and the The N-type functional area has a height difference.
  • the height difference is 0.5 ⁇ m to 5 ⁇ m.
  • the back contact solar cell further includes: an insulating layer disposed on a sidewall of the trench, the insulating layer insulating the P-type functional region and the N-type functional region.
  • the P-type functional region includes an intrinsic silicon film layer, a p-type doped silicon film layer, and a transparent conductive layer, the intrinsic silicon film layer, the p-type doped silicon film layer, and The transparent conductive layer is sequentially disposed on the protrusion or the groove, and an electrode is disposed on the transparent conductive layer;
  • the N-type functional region includes an intrinsic silicon film layer, an n-type doped silicon film layer, and a transparent conductive layer, the intrinsic silicon film layer, the n-type doped silicon film layer, and The transparent conductive layer is sequentially disposed in the trench or on the protrusion, and an electrode is disposed on the second transparent conductive layer.
  • the back contact solar cell further includes a passivation layer or an anti-reflection layer, or a passivation layer and an anti-reflection layer disposed on a front surface of the substrate.
  • the front side of the substrate has a pyramid shape.
  • the back-contact solar cell works by forming a PN junction between the substrate and the n-type doped silicon thin film layer and the p-type doped silicon thin film layer.
  • incident light is irradiated onto the PN junction, carriers are generated.
  • the photo-generated electrons are collected in the first transparent conductive layer through the first intrinsic silicon thin film layer and the n-type doped silicon thin film layer, and then led out by the first electrode;
  • the two intrinsic silicon thin film layers and the p-type doped silicon thin film layer are collected in a second transparent conductive layer and then led out by a second electrode.
  • the first intrinsic silicon thin film layer and the second intrinsic silicon thin film layer are used to passivate surface defects of the substrate.
  • the back-contact solar cell passes through a first surface and a second surface having a height difference, so that the N region and the P region disposed thereon have a height difference, thereby forming insulation between the two;
  • a third surface perpendicular to the first surface and the second surface (the side wall of the trench on the back surface of the substrate) is provided between the surfaces, and an insulating layer is provided on the third surface to further form the insulation between the N region and the P region.
  • the insulating layer may be a first intrinsic silicon thin film layer or a second intrinsic silicon thin film layer.
  • x may be from 1 to 2.

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Abstract

一种背接触太阳能电池及其制备方法，该制备方法包括：在衬底的背面形成第一功能区，第一功能区包括保留区和去除区；在保留区上形成保护层；除去去除区，并在衬底的背面形成沟槽；在沟槽内形成第二功能区；除去保护层；其中，第一功能区与第二功能区的导电类型不同。

Description

一种背接触太阳能电池及其制备方法
相关申请的交叉引用
本申请要求基于2018年06月15日提交的申请号为201810620412.3的中国申请的优先权，通过援引将其全部内容并入本文中。
技术领域
本申请涉及但不限于太阳能电池领域，特别涉及但不限于一种背接触太阳能电池及其制备方法。
背景技术
背接触太阳能电池是一种将P区(正电极)和N区(负电极)均放置在电池背面(非受光面)的电池。而由于P区和N区位于同一水平面上、且距离较近，使得P区和N区容易电性导通，导致电池的开路电压、短路电流和填充因子降低，从而影响电池能量转化效率的提高。
为了制备高效的太阳能电池，需要在P区和N区之间制备绝缘性能良好的背面图形。目前，多采用光刻法和激光法制备该背面图形。
发明概述
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
根据本申请的一种具体实施方式，提供一种背接触太阳能电池的制备方法，所述制备方法包括：
在衬底的背面形成第一功能区，所述第一功能区包括保留区和去除区；
在所述保留区上形成保护层；
除去所述去除区，并在所述衬底的背面形成沟槽；
在所述沟槽内形成第二功能区；
除去所述保护层；
其中，所述第一功能区与所述第二功能区的导电类型不同。
根据本申请的另一种具体实施方式，还提供了一种背接触太阳能电池，所述背接触太阳能电池由上述制备方法制备得到。
根据本申请的另一种具体实施方式，还提供了一种背接触太阳能电池，所述背接触太阳能电池包括：
衬底，所述衬底的背面具有凸起和沟槽；
设置在所述凸起上的P型功能区和设置在所述沟槽内的N型功能区，或设置在所述凸起上的N型功能区和设置在所述沟槽内的P型功能区；所述P型功能区和所述N型功能区具有高度差，所述高度差为0.5μm至5μm；以及
设置在所述沟槽侧壁上的绝缘层，所述绝缘层将所述P型功能区和所述N型功能区绝缘。
本申请的其它特征和优点将在随后的说明书中阐述，并且，部分地从说明书中变得更加清楚，或者通过实施本申请而了解。本申请的目的和其他优点可通过在说明书、权利要求书中所特别指出的结构来实现和获得。
附图概述
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，需要说明的是，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的一种背接触太阳能电池制备方法的流程图；
图2a-图2j为本申请实施例提供的背接触太阳能电池制备工艺的示意图；
图3为本申请实施例制备的背接触太阳能电池的结构示意图。
图中：1.晶硅衬底；2.第一本征硅薄膜层；3.第一掺杂硅薄膜层；4.第一透明导电层；5.保护层；6.第二本征硅薄膜层；7.第二掺杂硅薄膜层； 8.第二透明导电层；9.钝化层；10.减反射层；11.第一金属电极；12.第二金属电极。
详述
下面将结合附图对本申请实施例作详细描述。需要说明的是，除非另有定义，本申请实施例所用的所有技术术语均具有与本领域技术人员通常理解的相同的含义。在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互任意组合。
本申请的发明人发现，采用光刻技术制备背面图形需要进行多次光刻，导致整个工艺比较复杂，并且光刻工艺价格昂贵，不利于平价太阳能电池的生产；而采用激光工艺制备背面图形，容易使硅片体损伤和表面损伤，需要额外的工艺去除损伤，同样存在工艺复杂的问题。
根据本申请的一种具体实施方式，提供了一种背接触太阳能电池的制备方法，所述制备方法包括：在衬底的背面形成第一功能区，所述第一功能区包括保留区和去除区；在所述保留区上形成保护层；除去所述去除区，并在所述衬底的背面形成沟槽；在所述沟槽内形成第二功能区；除去所述保护层；其中，所述第一功能区与所述第二功能区的导电类型不同。
在一种具体实施方式中，所述制备方法还包括：在除去所述保护层之后，在所述保留区的第一功能区上形成第一电极；以及在所述第二功能区上形成第二电极。
在一种具体实施方式中，在所述保留区上形成保护层，包括：通过丝网印刷工艺在所述保留区上形成所述保护层；和/或将遮盖板平铺于所述保留区，形成所述保护层。
在一种具体实施方式中，所述通过丝网印刷工艺在所述保留区上形成所述保护层，包括：将丝网印刷网版铺设在所述第一功能区，所述丝网印刷网版覆盖所述去除区，露出所述保留区；将阻挡浆料通过所述丝网印刷网版印刷在所述第一功能区上；干燥并固化所述阻挡浆料；移走所述丝网印刷网版，在所述保留区上形成所述保护层；任选地，所述阻挡浆料包括高分子材料、 石蜡中的至少一种。
在一种具体实施方式中，除去所述去除区，并在所述衬底的背面形成沟槽，包括：通过刻蚀工艺除去所述去除区，暴露所述衬底的背面；在所述衬底的背面刻蚀出所述沟槽。
在一种具体实施方式中，所述沟槽的深度为0.5μm至5μm。
在一种具体实施方式中，所述除去所述保护层，包括：通过物理剥离和化学刻蚀中的至少一种方法除去所述保护层。
在一种具体实施方式中，所述制备方法还包括：在所述衬底的正面形成钝化层或减反射层，或形成钝化层和减反射层。
在一种具体实施方式中，所述制备方法还包括：在形成所述钝化层或所述减反射层之前，对所述衬底的正面进行制绒。
在一种具体实施方式中，所述保留区和所述去除区交替设置。
在一种具体实施方式中，所述在衬底的背面形成第一功能区，包括：在所述衬底的背面形成第一本征硅薄膜层；在所述第一本征硅薄膜层上形成第一掺杂硅薄膜层；在所述第一掺杂硅薄膜层上形成第一透明导电层；所述第一本征硅薄膜层、所述第一掺杂硅薄膜层和所述第一透明导电层形成所述第一功能区。
在一种具体实施方式中，所述在所述沟槽内形成第二功能区，包括：在所述沟槽内形成第二本征硅薄膜层；在所述第二本征硅薄膜层上形成第二掺杂硅薄膜层；在所述第二掺杂硅薄膜层上形成第二透明导电层；所述第二本征硅薄膜层、所述第二掺杂硅薄膜层和所述第二透明导电层形成所述第二功能区。
根据本申请的另一种具体实施方式，还提供了一种背接触太阳能电池，所述背接触太阳能电池由上述制备方法制备得到。
根据本申请的另一种具体实施方式，还提供了一种背接触太阳能电池，所述背接触太阳能电池包括：衬底，所述衬底的背面具有凸起和沟槽；设置在所述凸起上的P型功能区和设置在所述沟槽内的N型功能区，或设置在所述凸起上的N型功能区和设置在所述沟槽内的P型功能区；所述P型功能区 和所述N型功能区具有高度差，所述高度差为0.5μm至5μm；以及设置在所述沟槽侧壁上的绝缘层，所述绝缘层将所述P型功能区和所述N型功能区绝缘。
在一种具体实施方式中，其中，所述P型功能区包括本征硅薄膜层、p型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述p型掺杂硅薄膜层和所述透明导电层依次设置在所述凸起上或所述沟槽内，所述透明导电层上设置有电极；以及所述N型功能区包括本征硅薄膜层、n型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述n型掺杂硅薄膜层和所述透明导电层依次设置在所述沟槽内或所述凸起上，所述透明导电层上设置有电极。
在一种具体实施方式中，所述背接触太阳能电池还包括，设置在所述衬底的正面上的钝化层或减反射层，或钝化层和减反射层。
在一种具体实施方式中，所述衬底的正面为金字塔形状。
本申请实施例提供了一种背接触太阳能电池的制备方法，如图1所示，该制备方法包括：
步骤S1、在衬底的背面形成第一功能区，第一功能区包括保留区和去除区；
步骤S2、在保留区上形成保护层；
步骤S3、除去去除区，并在衬底的背面形成沟槽；
步骤S4、在沟槽内形成第二功能区，第一功能区与第二功能区的导电类型不同；
步骤S5、除去保护层。
制备时，首先在衬底的背面形成第一功能区，然后利用保护层形成掩膜，以保护第一功能区的保留区；在未被掩膜的去除区对应的衬底的背面形成沟槽，并在沟槽内形成第二功能区；最后除去掩膜(保护层)即可制备得到背接触太阳能电池。其中，衬底背面未形成沟槽的部分为与沟槽对应的凸起，保留区对应衬底背面的凸起部分，去除区对应衬底背面的沟槽部分。
在示例性实施例中，衬底可以选择晶硅衬底。
本申请实施例提供的制备方法只需要采用一次掩膜就能制备出具有绝缘 性能的背面图形，可避免采用光刻法和激光法，工艺简单，成本低。且采用该制备方法能够得到第一功能区和第二功能区之间具有高度差的背接触太阳能电池，该高度差避免了第一功能区和第二功能区之间接触，形成良好绝缘，避免了因二者导通而造成的开路电压、短路电流和填充因子的降低，从而提高了电池能量转化效率。
在上述的制备方法中，“第一功能区与第二功能区的导电类型不同”可以理解为，第一功能区可以为正电极或负电极，相应地，第二功能区为负电极或正电极；还可以理解为第一功能区可以为P型功能区(P区)或N型功能区(N区)，相应地，第二功能区为N型功能区(N区)或P型功能区(P区)。
对于步骤S1而言，如图2a所示，在晶硅衬底1的背面形成第一功能区可包括以下步骤：
步骤S101、在晶硅衬底1的背面形成第一本征硅薄膜层2；
步骤S102、在第一本征硅薄膜层2上形成第一掺杂硅薄膜层3；
步骤S103、在第一掺杂硅薄膜层3上形成第一透明导电层4；
第一本征硅薄膜层2、第一掺杂硅薄膜层3和第一透明导电层4形成第一功能区。
以第一功能区为N区的情况为例，首先，在晶硅衬底1的背面形成第一功能区。具体地，可根据实际情况形成具有不同层叠结构的N区。为了达到更好的电池能量转化效率，示例地，在晶硅衬底1的背面形成N区可包括以下步骤：
步骤S101、在晶硅衬底1的背面形成第一本征硅薄膜层2；
步骤S102、在第一本征硅薄膜层2上形成n型掺杂硅薄膜层；
步骤S103、在n型掺杂硅薄膜层上形成第一透明导电层4；
第一本征硅薄膜层2、n型掺杂硅薄膜层和第一透明导电层4形成第一功能区。
第一功能区也可设置为P区，此时第一掺杂硅薄膜层3为p型掺杂硅薄膜层。
其中，可通过沉积法在晶硅衬底1的背面形成上述第一功能区。
在示例性实施例中，可采用等离子体增强化学气相沉积法(Plasma Enhanced Chemical Vapor Deposition，PECVD)在晶硅衬底1的背面依次层叠沉积第一本征硅薄膜层2和第一掺杂硅薄膜层3，可采用物理气相沉积法(Physical Vapor Deposition，PVD)在第一掺杂硅薄膜层3上沉积第一透明导电层4。
在示例性实施例中，衬底可选用晶硅衬底1，例如，可选用n型单晶硅片或p型单晶硅片。在示例性实施例中，可选用n型单晶硅片作为衬底，且可使n型单晶硅片的厚度为100μm至200μm，电阻率为1Ωcm至10Ωcm。
在示例性实施例中，第一本征硅薄膜层2可以为非晶硅膜(a-Si:H)或非晶硅氧合金薄膜(a-SiO x:H)，且第一本征硅薄膜层2的厚度可以为1nm至10nm。
在示例性实施例中，第一掺杂硅薄膜层3可以为n型掺杂硅薄膜层，n型掺杂硅薄膜层可以为磷掺杂非晶硅层，例如可以为a-Si:H、a-SiO x:H、c-SiO x:H等中的任一种，且可使n型掺杂硅薄膜层的厚度为1nm至10nm。
在示例性实施例中，第一透明导电层4可以为透明导电氧化物层，如掺锡的氧化铟透明导电膜(indium tin oxide，ITO)、掺钨的氧化铟透明导电膜(indium tungsten oxide，IWO)、掺铝的氧化锌透明导电膜(aluminum-doped zinc oxide，AZO)或者掺铯的氧化铟透明导电膜(indium caesium oxide，ICO)等中的任一种，且可使第一透明导电层4的厚度为10nm至200nm。
在步骤S1中，为了使第一功能区包括保留区和去除区，可以在衬底背面的第一功能区上划分出保留区和去除区。在示例性实施例中，保留区和去除区可以交替设置在第一功能区上。保留区为最终形成的背接触太阳能电池的N区或P区，对应地，去除区为最终形成的背接触太阳能电池的P区或N区。
在示例性实施例中，可根据实际需要设置保留区和去除区的形状。考虑到制备工艺的简便性，可设置保留区和去除区为交替设置的长条形，例如为长方形。本申请实施例对保留区和去除区的面积比没有严格限定，实际制备中，可根据需要通过模拟、优化来确定。在示例性实施例中，可通过设置保 留区和去除区，使相邻的P区和N区的面积比为3:1。
另外，在沉积第一功能区之前，还可对衬底进行除去损伤层(saw damage remove，SDR)的RCA标准清洗，以除去衬底表面的有机物、颗粒和金属离子等污染，从而形成清洁的衬底表面。
对于步骤S2而言，保护层用于保护保留区，以避免后续工艺的破坏。在保留区上形成保护层，可通过多种方式实现。
在示例性实施例中，如图2b所示，可通过丝网印刷工艺在所述保留区上形成保护层5，可包括以下步骤：
步骤S201、将丝网印刷网版铺设在第一功能区，丝网印刷网版覆盖去除区，露出保留区；
步骤S202、将阻挡浆料通过丝网印刷网版印刷在第一功能区上；
步骤S203、干燥并固化阻挡浆料；
步骤S204、移走丝网印刷网版，在保留区上形成保护层5。
阻挡浆料可以为高分子材料、石蜡材料等中的至少一种。可采用烘干炉烘干阻挡浆料。
丝网印刷工艺具有对准精度高的优点，采用该丝网印刷工艺能够使所形成的保护层5准确覆盖保留区，满足设计要求。且采用丝网印刷方法形成保护层5，所使用的阻挡浆料价格低廉，能降低生产成本。
在示例性实施例中，还可采用遮盖板形成保护层5。
例如，可将遮盖板平铺于保留区，形成保护层5。
应用时，可采用紧固件将遮盖板紧固在保留区上，以使遮盖板贴紧保留区，形成对保留区的保护，避免后续工艺对保留区的破坏。
对于上述步骤S3而言，可采用刻蚀工艺除去去除区，并在衬底的背面形成沟槽。在示例性实施例中，如图2c、图2d、图2e所示，步骤S3可包括以下步骤：
步骤S301、通过刻蚀工艺除去去除区，暴露晶硅衬底1的背面；
步骤S302、在晶硅衬底1的背面刻蚀出沟槽。
在步骤S301中，可采用刻蚀(如湿化学刻蚀)工艺除去去除区，暴露晶硅衬底1的背面。在步骤S3中，可采用湿化学刻蚀法，通过控制刻蚀时间，在晶硅衬底1的背面刻蚀出沟槽，最终在晶硅衬底1的背面形成高度差。该高度差可使最终形成的第一功能区和第二功能区之间形成良好的绝缘，考虑到在实际应用中，沟槽过浅可能达不到绝缘效果，且过深可能造成对晶硅衬底1的破坏，因此，可使沟槽的深度为0.5μm至5μm。
在示例性实施例中，可首先采用第一刻蚀溶液(例如HF、HCl等溶液)刻蚀掉去除区(未被保护层5保护)的第一透明导电层4，如图2c所示；
然后采用第二刻蚀溶液(例如KOH、四甲基氢氧化铵(tetramethylammonium hydroxide，TMAH)等溶液)刻蚀掉去除区(未被保护层5保护)的第一掺杂硅薄膜层3和第一本征硅薄膜层2，如图2d所示；
最后采用第三刻蚀溶液(例如KOH、TMAH等溶液)，通过控制化学刻蚀时间，在晶硅衬底1的背面刻蚀出沟槽，如图2e所示。
湿化学刻蚀法具有工艺简单，成本低，方便控制，无损伤的优点，采用该湿化学刻蚀法能够非常方便地除去非晶硅，制备出需要的背面图形，且不会带来额外的损伤。
对于上述步骤S4而言，如图2f所示，在沟槽内形成与第一功能区的导电类型不同的第二功能区可包括以下步骤：
步骤S401、在沟槽内面形成第二本征硅薄膜层6；
步骤S402、在第二本征硅薄膜层6上形成第二掺杂硅薄膜层7；
步骤S403、在第二掺杂硅薄膜层7上形成第二透明导电层8；
第二本征硅薄膜层6、第二掺杂硅薄膜层7和第二透明导电层8形成第二功能区。
在示例性实施例中，当第一功能区为N区时，可使第二功能区为P区，此时在沟槽内形成第二功能区，可包括以下步骤：
步骤S401、在沟槽内形成第二本征硅薄膜层6；
步骤S402、在第二本征硅薄膜层6上形成p型掺杂硅薄膜层；
步骤S403、在p型掺杂硅基薄膜层上形成第二透明导电层8；
第二本征硅薄膜层6、p型掺杂硅薄膜层和第二透明导电层8形成第二功能区。
当第一功能区为P区时，第二功能区为N区，第二掺杂硅薄膜层7可以为n型掺杂硅薄膜层。
在步骤S4中，可通过沉积法在沟槽内形成上述第二功能区。
在示例性实施例中，可采用PECVD沉积法在晶硅衬底1的背面依次层叠沉积第二本征硅薄膜层6和第二掺杂硅薄膜层7，可采用PVD沉积法在第二掺杂硅薄膜层7上沉积第二透明导电层8。在晶硅衬底1的背面形成的第二功能区能够覆盖沟槽，也能够覆盖保护层5。
在示例性实施例中，第二本征硅薄膜层6可以为非晶硅膜(a-Si:H)或非晶硅氧合金薄膜(a-SiO x:H)，且第二本征硅薄膜层6的厚度可以为1nm至10nm。
在示例性实施例中，第二掺杂硅薄膜层7可以为p型掺杂硅薄膜层，例如，可以为硼掺杂非晶硅层，例如可以为a-Si:H、a-SiO x:H、c-SiO x:H等中的任一种，且可使p型掺杂硅薄膜层的厚度为从1nm至10nm。
在示例性实施例中，第二透明导电层8可以为透明导电氧化物层，如ITO薄膜、IWO薄膜、AZO薄膜或者ICO薄膜等中的任一种，且可使第二透明导电层8的厚度为10nm至200nm。
在示例性实施例中，在沉积第二功能区之前，还可对衬底进行RCA标准清洗，并除去残留的化学溶液，以形成清洁的衬底表面。
对于步骤S5而言，考虑到第二功能区能够覆盖沟槽，也能够覆盖保护层5，因此可采用物理剥离和化学刻蚀中的至少一种方法除去保护层5，同时剥离保护层5上的第二功能区(第二本征硅薄膜层6、第二掺杂硅薄膜层7和第二透明导电层8)，露出第一功能区。
在示例性实施例中，如图2g所示，可采用阻挡浆料去除溶液(例如，氢氟酸HF溶液等)除去阻挡浆料形成的保护层5，并且剥离保护层5上的第二本征硅薄膜层6、第二掺杂硅薄膜层7和第二透明导电层8，使晶硅衬底1 的背面同时呈现第一功能区和第二功能区。
当采用沉积法在沟槽内形成上述第二功能区时，可同时在沟槽的侧壁上形成第二本征硅薄膜层6(如图2g所示)。采用上述方法除去保护层5时，可保留形成在沟槽侧壁上的第二本征硅薄膜层6，该第二本征硅薄膜层6可形成第一功能区和第二功能区之间的另一道绝缘。
在背接触太阳能电池中，晶硅衬底1的正面为电池的受光面，为了提高电池的能量转化效率，如图1所示，上述制备方法还可以包括：
步骤S6、在衬底的正面形成钝化层或减反射层，或形成钝化层和减反射层。
在进行步骤S6之前，还可对衬底的正面进行RCA标准清洗，并除去残留的化学溶液，以形成清洁的衬底表面。
在示例性实施例中，如图2i所示，可采用PECVD沉积法在晶硅衬底1的正面沉积本征非晶硅层，形成钝化层9，该本征非晶硅层的厚度可为1nm至10nm；还可利用PVD沉积法在钝化层9上沉积透明导电层(例如，透明导电氧化物(transparent conductive oxide，TCO)薄膜)，形成减反射层10，该透明导电层的厚度可为10nm至200nm。
在示例性实施例中，还可在晶硅衬底1的正面形成磷掺杂非晶硅层，该磷掺杂非晶硅层的厚度可以为1nm至10nm，磷掺杂非晶硅层在晶硅衬底1的正面形成前表面场(front surface field，FSF)，实际制备中，可使该磷掺杂非晶硅层位于钝化层9和减反射层10之间。
在晶硅衬底1的正面形成钝化层9或减反射层10之前，如图2h所示，该制备方法还可包括：对晶硅衬底1的正面进行制绒。
在示例性实施例中，可以在碱溶液(KOH或TMAH)中对晶硅衬底1的正面进行制绒(此时，背面的第一透明导电层4和第二透明导电层8可对背面图形进行保护)。
通过制绒处理可在晶硅衬底1的正面形成金字塔形状，以减少电池表面光的反射损失。
在背接触太阳能电池中，为了便于太阳能电池中产生的载流子导出，如 图1所示，还可使上述制备方法包括：
步骤S7、在保留区的第一功能区上形成第一电极；以及在第二功能区上形成第二电极。
在示例性实施例中，如图2j所示，第一电极可以为第一金属电极11，第二电极可以为第二金属电极12，第一金属电极11和第二金属电极12可以为银栅、铜电极等中的至少一种。
制备时，可通过丝网印刷工艺分别在第一透明导电层4和第二透明导电层8上印刷电极，例如银栅；和/或通过电镀分别在第一透明导电层4和第二透明导电层8上制备电极，例如铜电极。
为了便于阐述，上文以“第一功能区为N区，第二功能区为P区”的情况为例，来说明本申请的制备方法，“第一功能区为P区，第二功能区为N区”的情况与之等同。本申请实施例还提供了一种背接触太阳能电池，该背接触太阳能电池由上述制备方法制备得到。
本申请实施例提供的由上述制备方法制备的背接触太阳能电池，形成在衬底上的第一功能区和第二功能区之间具有高度差，该高度差避免了第一功能区和第二功能区之间接触，形成良好绝缘，避免了因二者导通而造成的开路电压、短路电流和填充因子的降低，从而提高了电池能量转化效率。
本申请实施例提供的由上述方法制备得到的太阳能电池，如图3所示，该背接触太阳能电池包括：
晶硅衬底1，晶硅衬底1的背面设置有具有高度差的第一面和第二面；
依次设置在第一面的第一本征硅薄膜层2、第一掺杂硅薄膜层3、第一透明导电层4和第一金属电极11；以及
依次设置在第二面的第二本征硅薄膜层6、第二掺杂硅薄膜层7、第二透明导电层8和第二金属电极12；
其中，在晶硅衬底1的背面还设置有第三面，第三面位于第一面和第二面之间，且垂直于第一面和第二面；第三面上设置有绝缘层；
其中，在晶硅衬底1的正面还设置有钝化层9或减反射层10，或钝化层9和减反射层10。
本申请实施例还提供了一种背接触太阳能电池，所述背接触太阳能电池包括：衬底，所述衬底的背面具有凸起和沟槽；设置在所述凸起上的P型功能区和设置在所述沟槽内的N型功能区，或设置在所述凸起上的N型功能区和设置在所述沟槽内的P型功能区；所述P型功能区和所述N型功能区具有高度差。
在示例性实施例中，所述高度差为0.5μm至5μm。
在示例性实施例中，所述背接触太阳能电池还包括：设置在所述沟槽侧壁上的绝缘层，所述绝缘层将所述P型功能区和所述N型功能区绝缘。
在示例性实施例中，所述P型功能区包括本征硅薄膜层、p型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述p型掺杂硅薄膜层和所述透明导电层依次设置在所述凸起上或所述沟槽内，所述透明导电层上设置有电极；
在示例性实施例中，所述N型功能区包括本征硅薄膜层、n型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述n型掺杂硅薄膜层和所述透明导电层依次设置在所述沟槽内或所述凸起上，所述第二透明导电层上设置有电极。
在示例性实施例中，所述背接触太阳能电池还包括，设置在所述衬底的正面上的钝化层或减反射层，或钝化层和减反射层。
在示例性实施例中，所述衬底的正面为金字塔形状。
该背接触太阳能电池的工作原理为：在衬底与n型掺杂硅薄膜层和p型掺杂硅薄膜层之间形成PN结，当入射光照射到PN结上时，会产生载流子(光生电子和光生空穴)，光生电子通过第一本征硅薄膜层和n型掺杂硅薄膜层被收集在第一透明导电层中，然后由第一电极导出；而光生空穴通过第二本征硅薄膜层和p型掺杂硅薄膜层被收集在第二透明导电层中，然后由第二电极导出。其中，第一本征硅薄膜层和第二本征硅薄膜层用于钝化衬底的表面缺陷。
该背接触太阳能电池通过具有高度差的第一面和第二面，使得设置其上的N区和P区具有高度差，而形成二者之间的绝缘；同时通过在第一面和第二面之间设置垂直于第一面和第二面的第三面(即衬底背面的沟槽的侧壁)， 且在第三面设置绝缘层，进一步形成N区和P区之间的绝缘，避免了因二者导通而造成的开路电压、短路电流和填充因子的降低，从而提高了电池能量转化效率。
其中，该绝缘层可以为第一本征硅薄膜层或第二本征硅薄膜层。
可以理解的是，对于本申请示例性实施例中所涉及的SiO x，x可以为从1至2。
本公开内容是本申请实施例的原则的示例，并非对本申请作出任何形式上或实质上的限定，或将本申请限定到具体的实施方案。对本领域的技术人员而言，很显然本申请实施例的技术方案的要素、方法和系统等，可以进行变动、改变、改动、演变，而不背离如上所述的本申请的实施例、技术方案的，如权利要求中所定义的原理、精神和范围。这些变动、改变、改动、演变的实施方案均包括在本申请的等同实施例内，这些等同实施例均包括在本申请的由权利要求界定的范围内。虽然可以许多不同形式来使本申请实施例具体化，但此处详细描述的是本申请的一些实施方案。此外，本申请的实施例包括此处所述的各种实施方案的一些或全部的任意可能的组合，也包括在本申请的由权利要求界定的范围内。在本申请中或在任一个引用的专利、引用的专利申请或其它引用的资料中任何地方所提及的所有专利、专利申请和其它引用资料据此通过引用以其整体并入。
以上公开内容规定为说明性的而不是穷尽性的。对于本领域技术人员来说，本说明书会暗示许多变化和可选择方案。所有这些可选择方案和变化旨在被包括在本权利要求的范围内，其中术语“包括”意思是“包括，但不限于”。
在此完成了对本申请可选择的实施方案的描述。本领域技术人员可认识到此处所述的实施方案的其它等效变换，这些等效变换也为由附于本文的权利要求所包括。

Claims (15)

  1. 一种背接触太阳能电池的制备方法，所述制备方法包括：
    在衬底的背面形成第一功能区，所述第一功能区包括保留区和去除区；
    在所述保留区上形成保护层；
    除去所述去除区，并在所述衬底的背面形成沟槽；
    在所述沟槽内形成第二功能区；
    除去所述保护层；
    其中，所述第一功能区与所述第二功能区的导电类型不同。
  2. 根据权利要求1所述的制备方法，所述制备方法还包括：在除去所述保护层之后，在所述保留区的第一功能区上形成第一电极；以及在所述第二功能区上形成第二电极。
  3. 根据权利要求1所述的制备方法，其中，在所述保留区上形成保护层，包括：
    通过丝网印刷工艺在所述保留区上形成所述保护层；和/或将遮盖板平铺于所述保留区，形成所述保护层。
  4. 根据权利要求3所述的制备方法，其中，所述通过丝网印刷工艺在所述保留区上形成所述保护层，包括：
    将丝网印刷网版铺设在所述第一功能区，所述丝网印刷网版覆盖所述去除区，露出所述保留区；
    将阻挡浆料通过所述丝网印刷网版印刷在所述第一功能区上；
    干燥并固化所述阻挡浆料；
    移走所述丝网印刷网版，在所述保留区上形成所述保护层；
    任选地，所述阻挡浆料包括高分子材料、石蜡中的至少一种。
  5. 根据权利要求1所述的制备方法，其中，所述除去所述去除区，并在所述衬底的背面形成沟槽，包括：
    通过刻蚀工艺除去所述去除区，暴露所述衬底的背面；
    在所述衬底的背面刻蚀出所述沟槽；
    任选地，所述沟槽的深度为0.5μm至5μm。
  6. 根据权利要求1所述的制备方法，其中，所述除去所述保护层，包括：
    通过物理剥离和化学刻蚀中的至少一种方法除去所述保护层。
  7. 根据权利要求1所述的制备方法，所述制备方法还包括：
    在所述衬底的正面形成钝化层或减反射层，或形成钝化层和减反射层。
  8. 根据权利要求7所述的制备方法，所述制备方法还包括：
    在形成所述钝化层或所述减反射层之前，对所述衬底的正面进行制绒。
  9. 根据权利要求1所述的制备方法，其中，所述保留区和所述去除区交替设置。
  10. 根据权利要求1至9中任一项所述的制备方法，其中，所述在衬底的背面形成第一功能区，包括：
    在所述衬底的背面形成第一本征硅薄膜层；
    在所述第一本征硅薄膜层上形成第一掺杂硅薄膜层；
    在所述第一掺杂硅薄膜层上形成第一透明导电层；
    所述第一本征硅薄膜层、所述第一掺杂硅薄膜层和所述第一透明导电层形成所述第一功能区。
  11. 根据权利要求10所述的制备方法，其中，所述在所述沟槽内形成第二功能区，包括：
    在所述沟槽内形成第二本征硅薄膜层；
    在所述第二本征硅薄膜层上形成第二掺杂硅薄膜层；
    在所述第二掺杂硅薄膜层上形成第二透明导电层；
    所述第二本征硅薄膜层、所述第二掺杂硅薄膜层和所述第二透明导电层形成所述第二功能区。
  12. 一种背接触太阳能电池，所述背接触太阳能电池由权利要求1至11 中任一项所述的制备方法制备得到。
  13. 一种背接触太阳能电池，所述背接触太阳能电池包括：
    衬底，所述衬底的背面具有凸起和沟槽；
    设置在所述凸起上的P型功能区和设置在所述沟槽内的N型功能区，或设置在所述凸起上的N型功能区和设置在所述沟槽内的P型功能区；所述P型功能区和所述N型功能区具有高度差，所述高度差为0.5μm至5μm；以及
    设置在所述沟槽侧壁上的绝缘层，所述绝缘层将所述P型功能区和所述N型功能区绝缘。
  14. 根据权利要求13所述的背接触太阳能电池，其中，
    所述P型功能区包括本征硅薄膜层、p型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述p型掺杂硅薄膜层和所述透明导电层依次设置在所述凸起上或所述沟槽内，所述透明导电层上设置有电极；以及
    所述N型功能区包括本征硅薄膜层、n型掺杂硅薄膜层和透明导电层，所述本征硅薄膜层、所述n型掺杂硅薄膜层和所述透明导电层依次设置在所述沟槽内或所述凸起上，所述透明导电层上设置有电极。
  15. 根据权利要求13或14所述的背接触太阳能电池，还包括设置在所述衬底的正面上的钝化层或减反射层，或钝化层和减反射层；
    任选地，所述衬底的正面为金字塔形状。
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