Solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, and mainly provides a solar cell and a preparation method thereof. The preparation method of the solar cell comprises the following steps: providing an N-type silicon wafer, and respectively forming a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on two opposite surfaces of the N-type silicon wafer; forming an N-type doped microcrystalline silicon layer on the first intrinsic amorphous silicon layer and forming a P-type doped microcrystalline silicon layer on the second intrinsic amorphous silicon layer by using an intermittent CO2 plasma treatment process; and forming a first transparent conductive layer and a first electrode on the N-type doped microcrystalline silicon layer, and forming a second transparent conductive layer and a second electrode on the P-type doped microcrystalline silicon layer. The preparation method of the solar cell in the technical scheme of the invention can promote the crystallization of the oxygen-doped microcrystalline silicon, enhance the electrical properties of the microcrystalline silicon, properly reduce the thickness of the doped microcrystalline silicon layer, reduce the process time and reduce the production cost.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for preparing the same. Background Art

[0002] Silicon-based heterojunction solar cells are a type of bifacial cell that uses crystalline silicon as the absorption layer. They absorb photons to generate electron-hole pairs. Holes pass through the intrinsic passivation layer and the p-type doped layer into the transparent conductive film TCO and the metal electrode for hole collection; electrons pass through the intrinsic passivation layer and the n-type doped layer into the transparent conductive film TCO and the metal electrode for electron collection, thereby forming a photocurrent. Silicon-based heterojunction solar cells have simple process flow, high efficiency, low temperature coefficient, and energy saving through the entire low-temperature process. They do not have problems such as light-induced degradation (LID) and heat-assisted light-induced degradation (LeTID). Natural bifacial cells have the advantages of thin film and good weak light response. Therefore, heterojunction cell technology has always been a research hotspot in the photovoltaic field.

[0003] At present, due to the excellent photoelectric properties of doped microcrystalline silicon (μc-Si:H), it has gradually replaced doped amorphous silicon (a-Si:H) and applied to heterojunction cell structures, further improving the photoelectric conversion efficiency of heterojunction solar cells.

[0004] However, how to effectively improve the crystallization rate of doped microcrystalline silicon, reduce its activation energy, and improve electrical conductivity has become an urgent problem to be solved in the era of heterojunction microcrystalline. Summary of the invention

[0005] The present application provides a solar cell and a method for preparing the same to solve or alleviate the technical problems mentioned above. The method for preparing the solar cell in the technical solution of the present application can promote the crystallization of oxygen-doped microcrystalline silicon, enhance its electrical properties, and appropriately reduce the thickness of the doped microcrystalline silicon layer, reduce the process time, and reduce the production cost.

[0006] In a first aspect, an embodiment of the present application provides a method for preparing a solar cell, comprising: Provide N-type silicon wafers, Forming a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on two oppositely disposed surfaces of the N-type silicon wafer respectively; By introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process, an N-type doped microcrystalline silicon layer is formed on the first intrinsic amorphous silicon layer; By introducing a mixed gas containing a P-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process, a P-type doped microcrystalline silicon layer is formed on the second intrinsic amorphous silicon layer; forming a first transparent conductive layer on the N-type doped microcrystalline silicon layer, and forming a second transparent conductive layer on the P-type doped microcrystalline silicon layer; A first electrode is formed on the first transparent conductive layer, and a second electrode is formed on the second transparent conductive layer.

[0007] Optionally, when forming the N-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s; and / or When forming the P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s.

[0008] Optionally, when forming the N-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and as the deposition thickness increases, the single interval time gradually increases; and / or When forming the P-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and as the deposition thickness increases, the single interval time gradually increases.

[0009] Optionally, when forming the N-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of each treatment is independently 100W-500W; and / or When forming the P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of each treatment is independently 100W-500W.

[0010] Optionally, the crystallization rate of the N-type doped microcrystalline silicon layer is 40-60%; and / or The crystallization rate of the P-type doped microcrystalline silicon layer is 40-60%.

[0011] Optionally, when forming the N-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar; and / or When forming the P-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar.

[0012] Optionally, when forming the N-type doped microcrystalline silicon layer, the deposition temperature is 160-200° C.; and / or When forming the P-type doped microcrystalline silicon layer, the deposition temperature is 160-200°C.

[0013] Optionally, the thickness of the N-type doped microcrystalline silicon layer is 5-20 nm; and / or The thickness of the P-type doped microcrystalline silicon layer is 5-30 nm.

[0014] Optionally, when forming the first intrinsic amorphous silicon layer, the deposition temperature is 160-220° C. and the deposition pressure is 0.2-2 mbar; and / or When forming the second intrinsic amorphous silicon layer, the deposition temperature is 160-220° C. and the deposition pressure is 0.2-2 mbar.

[0015] In a second aspect, an embodiment of the present application provides a solar cell, comprising: An N-type silicon wafer, wherein the N-type silicon wafer has a first surface and a second surface arranged opposite to each other; A first intrinsic amorphous silicon layer, an N-type doped microcrystalline silicon layer, a first transparent conductive layer, and a first electrode are located on the first surface and sequentially stacked in a direction away from the N-type silicon wafer; A second intrinsic amorphous silicon layer, a P-type doped microcrystalline silicon layer, a second transparent conductive layer, and a second electrode are located on the second surface and sequentially stacked in a direction away from the N-type silicon wafer; Wherein, the N-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process; The P-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing a P-type doping gas into a vapor deposition device and utilizing an intermittent CO2 plasma treatment process.

[0016] The above technical solution adopted in the embodiment of the present application may have the following advantages: By using microcrystalline silicon (μc-SiO x In the early stage of the formation of :H), the corresponding doped microcrystalline silicon layer (N-type doped microcrystalline silicon layer or P-type doped microcrystalline silicon layer) is treated by intermittent CO2 plasma treatment process to form oxygen-doped microcrystalline silicon (μc-SiO x :H) layer can promote the crystallization of doped microcrystalline silicon, thereby enhancing its electrical properties, and can also appropriately reduce the thickness of the doped microcrystalline silicon layer, reduce the process time and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0018] Figure 1It is a flow chart of a method for preparing a solar cell provided in an embodiment of the present application.

[0019] Figure 2 It is a schematic diagram of the structure of a solar cell provided in an embodiment of the present application.

[0020] Description of reference numerals: 101, N-type silicon wafer; 201, first intrinsic amorphous silicon layer; 202, second intrinsic amorphous silicon layer; 301, N-type doped microcrystalline silicon layer; 302, P-type doped microcrystalline silicon layer; 401, first transparent conductive layer; 402, second transparent conductive layer; 501, first electrode; 502, second electrode. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. The same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0022] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a solar cell, comprising: S100: Provides N-type silicon wafers, S200: forming a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on two opposite sides of the N-type silicon wafer; S300: continuously introducing a mixed gas containing an N-type doping gas into a vapor deposition device, and using an intermittent CO2 plasma treatment process to form an N-type doped microcrystalline silicon layer on the first intrinsic amorphous silicon layer; S400: continuously introducing a mixed gas containing a P-type doping gas into a vapor deposition device, and using an intermittent CO2 plasma treatment process to form a P-type doped microcrystalline silicon layer on the second intrinsic amorphous silicon layer; S500: forming a first transparent conductive layer on the N-type doped microcrystalline silicon layer, and forming a second transparent conductive layer on the P-type doped microcrystalline silicon layer; S600: forming a first electrode on the first transparent conductive layer, and forming a second electrode on the second transparent conductive layer.

[0023] The growth of microcrystalline silicon is generally divided into three stages. The first stage forms an incubation layer, which has a larger amorphous silicon component and has a better passivation effect; the second stage forms a nucleation growth layer: the crystallization rate of the nucleation growth layer increases; the third stage is a saturation layer, which is mainly composed of microcrystalline phase and has a higher conductivity. x :H) in the early stage of formation (i.e., the first stage and the early stage of the second stage), the corresponding doped microcrystalline silicon layer (N-type doped microcrystalline silicon layer or P-type doped microcrystalline silicon layer) is treated by an intermittent CO2 plasma treatment process to form oxygen-doped microcrystalline silicon (μc-SiO x :H) layer can promote the crystallization of doped microcrystalline silicon, thereby enhancing its electrical properties, and can also appropriately reduce the thickness of the doped microcrystalline silicon layer, reduce the process time and reduce production costs.

[0024] In step S100, an N-type silicon wafer can be formed by cutting, pre-cleaning, doping and cleaning a single crystal ingot. The single crystal ingot is cut with diamond wire, tungsten wire or mortar to form an original silicon wafer with a thickness of 60-180um and a resistivity of 0.2-5Ω·m. By pre-cleaning, organic pollution and large particles on the surface of the original silicon wafer can be removed. The original silicon wafer is treated with doping by high-temperature tubular phosphorus diffusion or chain doping equipment to remove metal ion impurities in the original silicon wafer body and improve the quality of the silicon wafer. It is preferred to use high-temperature management diffusion doping, the doping temperature is 700-900℃, the process gas is nitrogen, oxygen, phosphorus oxychloride, and the square resistance of the silicon wafer after doping is 20-40Ω / sq. A wet acid solution (such as HF / HNO3 / HCl) is used to remove the oxide (PSG phosphorus silicate glass) layer produced on the surface of the silicon wafer during the doping process, and then an alkaline solution (such as KOH / NaOH / TMAH) is used with additives (such as IPA isopropyl alcohol, ammonium persulfate, polyhexamethylene biguanide, tetramethylammonium hydroxide, one or more) to perform polishing and texturing to form a pyramid-shaped surface light-trapping structure with a texture size of 1-5μm.

[0025] In some embodiments, in step S200, when forming the first intrinsic amorphous silicon layer, the deposition temperature is 160-220° C., and the deposition pressure is 0.2-2 mbar; and / or when forming the second intrinsic amorphous silicon layer, the deposition temperature is 160-220° C., and the deposition pressure is 0.2-2 mbar. Specifically, when forming the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer, the deposition temperature can be 160° C., 180° C., 200° C., or 220° C., respectively and independently, and the deposition pressure can be 0.2 mbar, 0.5 mbar, 0.8 mbar, 1 mbar, 1.3 mbar, 1.5 mbar, or 2 mbar, respectively and independently.

[0026] In an optional embodiment, in step S200, the thickness of the first intrinsic amorphous silicon layer is 2-10 nm, and the thickness of the second intrinsic amorphous silicon layer is 2-10 nm. Specifically, the thickness of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are respectively and independently 2 nm, 5 nm, 7 nm, 8 nm or 10 nm.

[0027] In an optional embodiment, a PECVD device may be used to form the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer; the frequency of the PECVD device power supply is 10-40 MHz; specifically, the frequency of the PECVD device power supply may be 13.56 MHz, 27 MHz, or 40 MHz. The gas used to form the first intrinsic amorphous silicon layer or the second intrinsic amorphous silicon layer includes all or a combination of silane (SiH4), hydrogen (H2), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O).

[0028] In step S300 and step S400, using an intermittent CO2 plasma treatment process means that the doped microcrystalline silicon layer is not continuously formed by using CO2 plasma, including a treatment stage and an interval stage. The specific operation is: a mixed gas containing N-type doping gas or a mixed gas containing P-type doping gas is introduced into a vapor deposition device to deposit and form a part of the doped microcrystalline silicon layer (N-type doped microcrystalline silicon layer or P-type doped microcrystalline silicon layer), after a period of deposition (i.e., the interval stage), the introduction of the mixed gas containing N-type doping gas or the mixed gas containing P-type doping gas is stopped, CO2 gas is introduced, and the CO2 gas is ionized to produce CO2 plasma, and the corresponding doped microcrystalline silicon layer is treated by using CO2 plasma, and after a period of treatment (i.e., the treatment stage), the introduction of CO2 is stopped; then a mixed gas containing N-type doping gas or a mixed gas containing P-type doping gas is introduced for a second time to deposit for a period of time to form a part of the doped microcrystalline silicon layer, and then the corresponding doped microcrystalline silicon layer is treated by using CO2 plasma, and then the treatment by using CO2 plasma is stopped, and this cycle is repeated multiple times.

[0029] In some embodiments, when forming an N-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s; and / or When forming a P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s.

[0030] When forming an N-type doped microcrystalline silicon layer and / or a P-type doped microcrystalline silicon layer, a single treatment time of CO2 plasma treatment is too short to achieve the effect of improving the crystallization rate, and a single treatment time that is too long will affect the thin film properties of the corresponding doped microcrystalline silicon layer; when the single treatment time is 5s-30s and the single interval time is 30s-120s, the crystallization rate of the doped microcrystalline silicon layer can be improved, and at the same time, the doped microcrystalline silicon layer can have good thin film properties.

[0031] In some embodiments, when forming an N-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and as the deposition thickness increases, the single interval time gradually increases; and / or When forming a P-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and as the deposition thickness increases, the single interval time gradually increases.

[0032] For example, when forming an N-type doped microcrystalline silicon layer, CO2 plasma treatment is performed 5 times, with an interval of 5 times, and the first interval time is less than the second interval time, less than the third interval time, less than the fourth interval time, and less than the fifth interval time. When forming a P-type doped microcrystalline silicon layer, the same is true. This is because as the thickness of the N-type doped microcrystalline silicon layer or the P-type doped microcrystalline silicon layer increases, the degree of crystallization of the film layer also increases. In order to make the overall crystallization rate of the N-type doped microcrystalline silicon layer or the P-type doped microcrystalline silicon layer more consistent, the single interval time needs to be gradually increased.

[0033] The horizontal line in A represents the portion of the N-type doped microcrystalline silicon layer that has been treated with CO2 plasma; the horizontal line in B represents the portion of the P-type doped microcrystalline silicon layer that has been treated with CO2 plasma.

[0034] In some embodiments, when forming an N-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of each treatment is independently 100W-500W; and / or When forming a P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of a single treatment is independently 100W-500W.

[0035] In some embodiments, the crystallization rate of the N-type doped microcrystalline silicon layer is 40-60%; and / or The crystallization rate of the P-type doped microcrystalline silicon layer is 40-60%.

[0036] In the embodiment of the present application, the crystallization rate of the N-type doped microcrystalline silicon layer and the P-type doped microcrystalline silicon layer is improved by a CO2 plasma treatment process. Specifically, the crystallization rates of the N-type doped microcrystalline silicon layer and the P-type doped microcrystalline silicon layer are 40%, 45%, 50%, 55% or 60% respectively and independently.

[0037] In some embodiments, when forming an N-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar; and / or When forming a P-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar.

[0038] In some embodiments, when forming the N-type doped microcrystalline silicon layer, the deposition temperature is 160-200° C.; and / or When forming a P-type doped microcrystalline silicon layer, the deposition temperature is 160-200°C.

[0039] In some embodiments, the thickness of the N-type doped microcrystalline silicon layer is 5-20 nm; and / or The thickness of the P-type doped microcrystalline silicon layer is 5-30 nm.

[0040] The mixed gas containing N-type doping gas includes all or a combination of SiH4, H2, CO2, CH4, N2O, and PH3; The mixed gas containing P-type doping gas includes all or a combination of SiH4, H2, B2H6, and TMB (trimethyl boron).

[0041] In an optional embodiment, a plasma enhanced chemical vapor deposition (PECVD) device may be used to form an N-type doped microcrystalline silicon layer and a P-type doped microcrystalline silicon layer, and the frequency of the PECVD device power supply is 10-40 MHz; specifically, the frequency of the PECVD device power supply may be 13.56 MHz, 26 MHz or 40 MHz.

[0042] It should be noted that the order of performing step S300 and step S400 is not fixed. Step S300 may be performed first and then step S400, or step S400 may be performed first and then step S300.

[0043] In an optional embodiment, in step S500, a physical vapor deposition (PVD) device may be used to form the first transparent conductive (TCO) layer and the second transparent conductive layer, and the power density of the PVD device is 2-8KW / m 2 , the process gases for forming the first TCO layer or the second TCO layer are Ar, O2 and H2, the process pressure is 0.3-0.8 Pa, and the process temperature is 0-200° C. The thickness of the first TCO layer and the second TCO layer can be 50-100 nm respectively and independently, and the materials of the first TCO layer and the second TCO layer can be one or more of tin-doped indium oxide (ITO), tungsten-doped indium oxide (IWO), cerium-doped indium oxide (ICO), (SCOT), and VTTO respectively and independently.

[0044] In an optional embodiment, in step S600, the first electrode and / or the second electrode can be formed by screen printing, laser transfer or electroplating; specifically, the first electrode and / or the second electrode can be formed by screen printing, laser transfer of low-temperature silver paste, low-temperature copper paste or silver-coated copper paste, or by electroplating one or more of Al, Ti, Ni, Co, Ag, Cu, Sn, etc. to form the first electrode and / or the second electrode.

[0045] like Figure 2 As shown, an embodiment of the present application provides a solar cell, comprising: An N-type silicon wafer 101, wherein the N-type silicon wafer 101 has a first surface and a second surface that are oppositely disposed; A first intrinsic amorphous silicon layer 201, an N-type doped microcrystalline silicon layer 301, a first transparent conductive layer 401, and a first electrode 501 are sequentially stacked on the first surface and in a direction away from the N-type silicon wafer 101; A second intrinsic amorphous silicon layer 202, a P-type doped microcrystalline silicon layer 302, a second transparent conductive layer 402, and a second electrode 502 are sequentially stacked on the second surface and in a direction away from the N-type silicon wafer 101; The N-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process; The P-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing a P-type doping gas into a vapor deposition device and utilizing an intermittent CO2 plasma treatment process.

[0046] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0047] Example 1 The specific structure of the solar cell of Example 1 includes: An N-type silicon wafer, wherein the N-type silicon wafer has a first surface and a second surface that are arranged opposite to each other; A first intrinsic amorphous silicon layer, an N-type doped microcrystalline silicon layer, a first transparent conductive layer, and a first electrode are located on the first surface and sequentially stacked in a direction away from the N-type silicon wafer; A second intrinsic amorphous silicon layer, a P-type doped microcrystalline silicon layer, a second transparent conductive layer, and a second electrode are located on the second surface and sequentially stacked in a direction away from the N-type silicon wafer; The N-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process; The P-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing a P-type doping gas into a vapor deposition device and utilizing an intermittent CO2 plasma treatment process.

[0048] The method for preparing a solar cell of embodiment 1 comprises: S110: Provides N-type silicon wafers, S210: using a PECVD device, forming a first intrinsic amorphous silicon layer with a thickness of 6 nm on the first surface of the N-type silicon wafer, and forming a second intrinsic amorphous silicon layer with a thickness of 6 nm on the second surface of the N-type silicon wafer; wherein the deposition temperature is 200° C. and the deposition pressure is 1 mbar; S310: continuously introducing a mixed gas containing N-type doping gas (including SiH4, H2 and PH3) into the vapor deposition equipment, introducing CO2 for the first time, and plasmatizing the CO2, and treating the surface of the film layer with CO2 plasma, with a treatment power of 450W. After treating for 10 seconds, stop introducing CO2 and stop plasmatizing; S320: After an interval of 50 seconds, CO2 is introduced for the second time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, and the treatment power is 350W. After 15 seconds of treatment, the introduction of CO2 and the plasmatization are stopped; S330: After an interval of 80 seconds, CO2 is introduced for the third time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, with a treatment power of 300 W. After 20 seconds of treatment, the introduction of CO2 is stopped, and the plasmatization is stopped; S340: After an interval of 100 seconds, CO2 is introduced for the fourth time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, with a treatment power of 250 W. After 25 seconds of treatment, the introduction of CO2 and the plasmatization are stopped; S350: After an interval of 120 seconds, CO2 is introduced for the fifth time and the CO2 is plasmatized. The surface of the film layer is treated with CO2 plasma again. The treatment power is 200W. After 30 seconds of treatment, the introduction of CO2 and the plasmatization are stopped. S360: continuously introducing a mixed gas containing an N-type doping gas, and finally forming an N-type doped microcrystalline silicon layer with a thickness of 15 nm on the first intrinsic amorphous silicon layer; In steps S310-S360, the deposition temperature is 180°C, the deposition pressure in the CO2 plasma treatment stage is 0.5 mbar, and the deposition pressure in the interval stage when the CO2 is stopped is 3 mbar; S410: continuously introducing a mixed gas containing a P-type doping gas (including SiH4, H2 and TMB) into the vapor deposition equipment, introducing CO2 for the first time, and plasmatizing the CO2, and treating the surface of the film layer with CO2 plasma, with a treatment power of 450W. After treating for 10 seconds, stop introducing CO2 and stop plasmatizing; S420: After an interval of 50 seconds, CO2 is introduced for the second time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, and the treatment power is 350W. After 15 seconds of treatment, the introduction of CO2 and the plasmatization are stopped; S430: After an interval of 80 seconds, CO2 is introduced for the third time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, with a treatment power of 300 W. After 20 seconds of treatment, the introduction of CO2 is stopped, and the plasmatization is stopped; S440: After an interval of 100 seconds, CO2 is introduced for the fourth time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, with a treatment power of 250W. After 25 seconds of treatment, the introduction of CO2 and the plasmatization are stopped; S450: After an interval of 120 seconds, CO2 is introduced for the fifth time, and the CO2 is plasmatized, and the surface of the film layer is treated again with CO2 plasma, with a treatment power of 200 W. After 30 seconds of treatment, the introduction of CO2 is stopped, and the plasmatization is stopped; S460: continuously introducing a mixed gas containing a P-type doping gas, and finally forming a P-type doped microcrystalline silicon layer with a thickness of 15 nm on the second intrinsic amorphous silicon layer; In steps S410-S460, the deposition temperature is 180°C, the deposition pressure in the CO2 plasma treatment stage is 0.5 mbar, and the deposition pressure in the interval stage when the CO2 is stopped is 3 mbar; S510: using a PVD device, forming a first transparent conductive layer with a thickness of 80 nm on the N-type doped microcrystalline silicon layer, and forming a second transparent conductive layer with a thickness of 80 nm on the P-type doped microcrystalline silicon layer; S620: forming a silver electrode on the first transparent conductive layer and forming a silver electrode on the second transparent conductive layer by screen printing.

[0049] Example 2 The solar cell of Example 2 has a similar structure to that of Example 1, except that, in the solar cell of Example 2, the thickness of the N-type doped microcrystalline silicon layer is 12 nm, and the thickness of the P-type doped microcrystalline silicon layer is 12 nm.

[0050] The solar cell of Example 2 is prepared by a preparation method similar to that of Example 1, except that the preparation method of the solar cell of Example 2 does not include step S350 and step S450.

[0051] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the specific structure and preparation method of the solar cell of Comparative Example 1.

[0052] Comparative Example 1 The solar cell of Comparative Example 1 has a similar structure to that of the solar cell of Example 1, except that, in the solar cell of Comparative Example 1, the crystallization rate of the N-type doped microcrystalline silicon layer is 45%, and the crystallization rate of the P-type doped microcrystalline silicon layer is 43%.

[0053] The solar cell of Comparative Example 1 is prepared by a preparation method similar to that of Example 1, the only difference being that, in the preparation method of the solar cell of Comparative Example 1, the N-type doped microcrystalline silicon layer and the P-type doped microcrystalline silicon layer do not utilize an intermittent CO2 plasma treatment process.

[0054] The present application also manufactures the solar cells of Example 1 and Comparative Example 1 into corresponding photovoltaic modules, and performs performance tests on the corresponding photovoltaic modules, thereby obtaining the short-circuit current density Jsc, open-circuit voltage Voc, fill factor FF, and photoelectric conversion efficiency PCE of the corresponding photovoltaic modules. The test results are shown in Table 1.

[0055] Table 1

[0056] It can be seen from the data in Table 1 that the filling factor and photoelectric conversion efficiency of the solar cells of Examples 1 and 2 of the present application are improved compared with Comparative Example 1. This shows that in Examples 1 and 2 of the present application, the intermittent CO2 plasma treatment method can effectively promote the crystallization of the doped microcrystalline silicon layer, thereby improving the conductivity, increasing the cell filling factor, and further improving the cell efficiency.

[0057] In summary, in the embodiment of the present application, by x :H) in the early stage of formation (i.e., the first stage and the early stage of the second stage), the corresponding doped microcrystalline silicon layer (N-type doped microcrystalline silicon layer or P-type doped microcrystalline silicon layer) is treated by an intermittent CO2 plasma treatment process to form oxygen-doped microcrystalline silicon (μc-SiO x :H) layer can promote the crystallization of doped microcrystalline silicon, thereby enhancing its electrical properties, and can also appropriately reduce the thickness of the doped microcrystalline silicon layer, reduce the process time and reduce production costs.

[0058] It should be noted that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0059] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0060] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0061] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0062] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a solar cell, characterized in that: include Provide N-type silicon wafers, Forming a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on two oppositely disposed surfaces of the N-type silicon wafer respectively; By introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process, an N-type doped microcrystalline silicon layer is formed on the first intrinsic amorphous silicon layer; By introducing a mixed gas containing a P-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process, a P-type doped microcrystalline silicon layer is formed on the second intrinsic amorphous silicon layer; forming a first transparent conductive layer on the N-type doped microcrystalline silicon layer, and forming a second transparent conductive layer on the P-type doped microcrystalline silicon layer; A first electrode is formed on the first transparent conductive layer, and a second electrode is formed on the second transparent conductive layer.

2. The method for preparing a solar cell according to claim 1, characterized in that: When forming the N-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s; and / or When forming the P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, the single treatment time is independently 5s-30s, and the single interval time is independently 30s-120s.

3. The method for preparing a solar cell according to claim 1, characterized in that: When forming the N-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and the single time interval gradually increases with the increase of deposition thickness; and / or When forming the P-type doped microcrystalline silicon layer, the number of times of CO2 plasma treatment is 3-8 times, and as the deposition thickness increases, the single interval time gradually increases.

4. The method for preparing a solar cell according to claim 1, characterized in that: When forming the N-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of each treatment is independently 100W-500W; and / or When forming the P-type doped microcrystalline silicon layer, the number of CO2 plasma treatments is 3-8 times, and the power of each treatment is independently 100W-500W.

5. The method for preparing a solar cell according to claim 1, characterized in that: The crystallization rate of the N-type doped microcrystalline silicon layer is 40-60%; and / or The crystallization rate of the P-type doped microcrystalline silicon layer is 40-60%.

6. The method for preparing a solar cell according to claim 1, characterized in that: When forming the N-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar; and / or When forming the P-type doped microcrystalline silicon layer, the deposition pressure in the CO2 plasma treatment stage is 0.2-0.6 mbar, and the deposition pressure in the interval stage is 0.5-5 mbar.

7. The method for preparing a solar cell according to claim 1, characterized in that: When forming the N-type doped microcrystalline silicon layer, the deposition temperature is 160-200° C.; and / or When forming the P-type doped microcrystalline silicon layer, the deposition temperature is 160-200°C.

8. The method for preparing a solar cell according to claim 1, characterized in that: The thickness of the N-type doped microcrystalline silicon layer is 5-20 nm; and / or The thickness of the P-type doped microcrystalline silicon layer is 5-30 nm.

9. The method for preparing a solar cell according to claim 1, characterized in that: When forming the first intrinsic amorphous silicon layer, the deposition temperature is 160-220° C. and the deposition pressure is 0.2-2 mbar; and / or When forming the second intrinsic amorphous silicon layer, the deposition temperature is 160-220° C. and the deposition pressure is 0.2-2 mbar.

10. A solar cell, characterized in that: include: An N-type silicon wafer, wherein the N-type silicon wafer has a first surface and a second surface arranged opposite to each other; A first intrinsic amorphous silicon layer, an N-type doped microcrystalline silicon layer, a first transparent conductive layer, and a first electrode are located on the first surface and sequentially stacked in a direction away from the N-type silicon wafer; A second intrinsic amorphous silicon layer, a P-type doped microcrystalline silicon layer, a second transparent conductive layer, and a second electrode are located on the second surface and sequentially stacked in a direction away from the N-type silicon wafer; Wherein, the N-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing an N-type doping gas into a vapor deposition device and using an intermittent CO2 plasma treatment process; The P-type doped microcrystalline silicon layer is formed by introducing a mixed gas containing a P-type doping gas into a vapor deposition device and utilizing an intermittent CO2 plasma treatment process.

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