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 a silicon substrate; sequentially forming a first transparent conductive oxide layer, a first sacrificial layer and a first metal seed layer on the first surface of the silicon substrate; forming a patterned first mask layer on the first metal seed layer to expose the first metal seed layer in the first metal region; depositing a metal material on the first metal seed layer in the first metal region by adopting an electroplating process to form a first metal electrode; completely removing the first mask layer and the first metal seed layer in the first non-metal region; wherein the first transparent conductive oxide layer is an acid-resistant transparent conductive oxide layer; the first sacrificial layer is a non-acid-resistant transparent conductive oxide layer. The solar cell provided by the technical scheme of the invention has good electrical performance, stability and photoelectric conversion rate.

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] In the photovoltaic field, heterojunction solar cells (HJT) have the advantages of simple structure, low process temperature, good passivation effect, high open circuit voltage, good temperature characteristics, and double-sided power generation. It is one of the hot spots for high conversion efficiency silicon-based solar cells. HJT technology has obvious advantages in conversion efficiency, process steps and temperature, double-sidedness, anti-attenuation, etc., and will become the mainstream of the third-generation cell technology.

[0003] Although HJT has many advantages, the current cost of heterojunction solar cells is higher than that of passivated emitter and rear cells (PERC). Therefore, whether HJT can quickly replace PERC depends mainly on whether HJT can achieve cost reduction. Battery cost reduction can be achieved by reducing silver consumption, domestic substitution processes, and gate line cost reduction technologies such as copper processes. There are currently two main directions for gate line cost reduction: silver-coated copper slurry and electroplating copper. The current electroplating copper method is to sputter a full seed layer on the transparent conductive oxide (TCO) layer, and then make a mask (dry film-exposure-development) to expose the area that needs to be electroplated, and then electroplating copper and other metal layers, and finally remove the mask and seed layer; although the full seed layer method has the advantages of high photoelectric conversion efficiency, low cost, and suitability for mass production, the process of this method is too cumbersome, has high quality requirements for TCO, and the electroplating wastewater is difficult to treat. In addition, the seed layer is difficult to remove, and the TCO is easily damaged when the seed layer is removed. Summary of the invention

[0004] 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 not only avoid the diffusion contamination of copper and silicon, improve the electrical performance and stability of the solar cell, but also reduce the shading loss and improve the photoelectric conversion rate of the solar cell.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a solar cell, comprising: Providing a silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; forming a first transparent conductive oxide layer, a first sacrificial layer, and a first metal seed layer in sequence on the first surface; forming a patterned first mask layer on the first metal seed layer, wherein the first mask layer covers the first metal seed layer located in the first non-metal region and exposes the first metal seed layer located in the first metal region; Depositing a metal material on the first metal seed layer located in the first metal region by an electroplating process to form a first metal electrode; Completely removing the first mask layer and the first metal seed layer located in the first non-metallic area; Wherein, the first transparent conductive oxide layer is an acid-resistant transparent conductive oxide layer; and the first sacrificial layer is a non-acid-resistant transparent conductive oxide layer.

[0006] Optionally, the method for preparing a solar cell further includes: forming a second transparent conductive oxide layer, a second sacrificial layer, and a second metal seed layer in sequence on the second surface; forming a patterned second mask layer on the second metal seed layer, wherein the second mask layer covers the second metal seed layer located in the second non-metal region and exposes the second metal seed layer located in the second metal region; Depositing a metal material on the second metal seed layer located in the second metal region by an electroplating process to form a second metal electrode; Completely removing the second mask layer and the second metal seed layer in the second non-metal region; Wherein, the second transparent conductive oxide layer is an acid-resistant transparent conductive oxide layer; and the second sacrificial layer is a non-acid-resistant transparent conductive oxide layer.

[0007] Optionally, the material of the first transparent conductive oxide layer is an annealed indium and / or tin-containing transparent conductive oxide.

[0008] Optionally, the material of the first transparent conductive oxide layer includes one or more of crystallized indium tin oxide (ITO), crystallized tungsten-doped indium oxide (IWO), crystallized cerium-doped indium oxide (ICO), crystallized molybdenum-doped indium oxide (IMO), crystallized indium oxide, annealed tin oxide, annealed fluorine-doped tin oxide (FTO), annealed antimony-doped tin oxide (ATO), and crystallized VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 .

[0009] Optionally, the material of the first sacrificial layer includes amorphous indium tin oxide (ITO), amorphous tungsten-doped indium oxide (IWO), amorphous cerium-doped indium oxide (ICO), amorphous molybdenum-doped indium oxide (IMO), amorphous indium oxide (In 2 O 3), amorphous zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), amorphous indium gallium zinc oxide (IGZO), amorphous nickel zinc oxide (NZO), zinc oxide, amorphous VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 .

[0010] Optionally, the first transparent conductive oxide layer comprises a plurality of sub-transparent conductive oxide layers stacked in sequence; The materials of each sub-transparent conductive oxide layer are different.

[0011] Optionally, the method for preparing the first transparent conductive oxide layer comprises: A transparent conductive oxide is deposited on the first surface, and annealed in an environment of 180-220° C. for 20-40 minutes to form the first transparent conductive oxide layer.

[0012] Optionally, the method for preparing the first transparent conductive oxide layer comprises: Depositing a first transparent conductive oxide on the first surface, and annealing in an environment of 180-220° C. for 20-40 minutes to form a first sub-transparent conductive oxide layer; Depositing a second transparent conductive oxide on the first sub-transparent conductive oxide layer, and annealing in an environment of 180-220° C. for 20-40 minutes to form a second sub-transparent conductive oxide layer; wherein the first transparent conductive oxide and the second transparent conductive oxide are different; The first transparent conductive oxide layer and the second transparent conductive oxide layer together constitute the first transparent conductive oxide layer.

[0013] Optionally, after completely removing the first mask layer and the first metal seed layer located in the first non-metallic region, the method for preparing a solar cell further includes: Performing baking annealing on the first metal electrode and the first metal seed layer located in the first metal region; The annealing temperature is 180-220° C. and the annealing time is 20-40 min.

[0014] Optionally, the thickness of the first sacrificial layer is 3-8 nm; and / or The thickness of the first transparent conductive oxide layer is 60-100 nm.

[0015] Optionally, the material of the first metal electrode includes one or both of copper and tin; and / or The material of the first metal seed layer includes one or more of copper, nickel and aluminum.

[0016] Optionally, the first sacrificial layer completely covers the first surface having the first transparent conductive oxide layer.

[0017] In a second aspect, an embodiment of the present application provides a solar cell formed by any of the above-mentioned methods for preparing a solar cell.

[0018] The above technical solution adopted in the embodiment of the present application may have the following advantages: In the technical solution of the present application, a first sacrificial layer is provided between the first transparent conductive oxide (TCO) layer and the first metal seed layer, which reduces the corrosion of the first metal seed layer to the first TCO layer and reduces the optical and electrical losses. Moreover, the first transparent conductive oxide layer has a good corrosion resistance; and the material of the first sacrificial layer is easily removed by corrosion, which is conducive to completely removing the first metal seed layer in the first non-metallic area, thereby reducing the shading loss and improving the photoelectric conversion rate of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 is a flow chart of a method for preparing a solar cell according to an embodiment of the present application; Figure 2-5 It is a schematic diagram of a structure formed in the method for preparing a solar cell according to an embodiment of the present application.

[0021] Description of reference numerals: 100, silicon substrate; 200, intrinsic amorphous silicon layer; 310, N-type doped microcrystalline silicon layer; 320, P-type doped microcrystalline silicon layer; 410, first transparent conductive oxide layer; 420, second transparent conductive oxide layer; 510, first sacrificial layer; 520, second sacrificial layer; 610, first metal seed layer; 620, second metal seed layer; 710, first mask layer; 720, second mask layer; 810, first metal electrode; 820, second metal electrode. DETAILED DESCRIPTION

[0022] 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. Wherein 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, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0023] like Figures 1 to 5 As shown, the embodiment of the present application provides a method for preparing a solar cell, comprising: S110: providing a silicon substrate 100, wherein the silicon substrate 100 includes a first surface and a second surface that are oppositely disposed; S210: forming a first transparent conductive oxide layer 410, a first sacrificial layer 510, and a first metal seed layer 610 on the first surface in sequence; wherein the first transparent conductive oxide layer 410 is an acid-resistant transparent conductive oxide layer; and the first sacrificial layer 510 is a non-acid-resistant transparent conductive oxide layer; S310: forming a patterned first mask layer 710 on the first metal seed layer 610, wherein the first mask layer 710 covers the first metal seed layer 610 located in the first non-metal region and exposes the first metal seed layer 610 located in the first metal region; S410: using an electroplating process to deposit a metal material on the first metal seed layer 610 located in the first metal region to form a first metal electrode 810; S510: completely remove the first mask layer 710 and the first metal seed layer 610 located in the first non-metal region.

[0024] It should be noted that, in the present application, the acid-resistant transparent conductive oxide layer refers to a transparent conductive oxide layer that is not corroded by acid after being immersed in a sulfuric acid solution (with a concentration of 5%) for 3 minutes, and has good corrosion resistance; the non-acid-resistant transparent conductive oxide layer refers to a transparent conductive oxide layer that is corroded by acid after being immersed in a sulfuric acid solution (with a concentration of 5%) for less than 3 minutes, and has poor corrosion resistance. In an optional embodiment, the acid-resistant transparent conductive oxide layer is a transparent conductive oxide layer that is not corroded by acid after being immersed in a sulfuric acid solution (with a concentration of 5%) for 4 minutes, and the non-acid-resistant transparent conductive oxide layer is a transparent conductive oxide layer that is corroded by acid after being immersed in a sulfuric acid solution (with a concentration of 5%) for less than 2 minutes.

[0025] In the embodiment of the present application, a first sacrificial layer is provided between the first transparent conductive oxide (TCO) layer and the first metal seed layer, which reduces the corrosion of the first metal seed layer to the first TCO layer and reduces the optical and electrical losses. Moreover, the first transparent conductive oxide layer has a good corrosion resistance; and the first sacrificial layer is easily removed by corrosion, which is conducive to completely removing the first metal seed layer in the first non-metallic region, thereby reducing the shading loss and improving the photoelectric conversion rate of the solar cell.

[0026] In step S110, a silicon substrate is provided, including: pre-cleaning, impurity gettering, and cleaning and texturing the silicon substrate.

[0027] The silicon substrate can be an N-type silicon substrate or a P-type silicon substrate; organic pollution and large particles on the surface of the silicon substrate can be removed through pre-cleaning; the silicon substrate is treated with impurities using high-temperature tubular phosphorus diffusion or chain impurity gettering equipment to remove metal ion impurities in the silicon substrate and improve the quality of the silicon substrate; the silicon substrate is polished and textured using chemical solvents to form a surface light-trapping structure with a pyramid shape to enhance the light absorption effect.

[0028] like Figure 2 As shown, before forming the first TCO layer, the method for preparing a solar cell further includes: S120: forming an intrinsic amorphous silicon layer 200 on both the first surface and the second surface of the silicon substrate 100; S130 : forming doped microcrystalline silicon layers having different doping types on the two intrinsic amorphous silicon layers 200 .

[0029] The intrinsic amorphous silicon layer can reduce the recombination loss of carriers during the injection process and improve the photoelectric performance of solar cells; like Figure 2 As shown, in step S130, an N-type doped microcrystalline silicon layer 310 may be formed on the intrinsic amorphous silicon layer located on the first surface, and a P-type doped microcrystalline silicon layer 320 may be formed on the intrinsic amorphous silicon layer located on the second surface. In step S130, a P-type doped microcrystalline silicon layer may be formed on the intrinsic amorphous silicon layer located on the first surface, and an N-type doped microcrystalline silicon layer may be formed on the intrinsic amorphous silicon layer located on the second surface. The doped microcrystalline silicon layer having a doping type different from that of the silicon substrate forms a PN junction with the silicon substrate.

[0030] like Figures 2 to 5 As shown, in some embodiments, the method for preparing a solar cell further includes: S220: forming a second transparent conductive oxide layer 420, a second sacrificial layer 520, and a second metal seed layer 620 in sequence on the second surface; S320: forming a patterned second mask layer 720 on the second metal seed layer 620, wherein the second mask layer 720 covers the second metal seed layer 620 located in the second non-metal region and exposes the second metal seed layer 620 located in the second metal region; S420: using an electroplating process to deposit a metal material on the second metal seed layer 620 located in the second metal region to form a second metal electrode 820; S520: completely removing the second mask layer 720 and the second metal seed layer 620 located in the second non-metal region; The second transparent conductive oxide layer 420 is an acid-resistant transparent conductive oxide layer; and the second sacrificial layer 520 is a non-acid-resistant transparent conductive oxide layer.

[0031] In some embodiments, the material of the first transparent conductive oxide layer is an annealed indium and / or tin-containing transparent conductive oxide.

[0032] In an optional embodiment, the material of the second transparent conductive oxide layer is an annealed indium and / or tin-containing transparent conductive oxide.

[0033] The transparent conductive oxide containing indium and / or tin itself has good chemical stability and good corrosion resistance. The TCO layer formed after annealing has a more uniform distribution of internal chemical composition, reducing the difference in local chemical composition, thereby further improving the corrosion resistance; in addition, after annealing, some indium-containing transparent conductive oxides form crystallized transparent conductive oxides, and the crystal structure becomes more complete and ordered, reducing crystal defects, thereby improving the corrosion resistance of the TCO layer.

[0034] In some embodiments, the material of the first transparent conductive oxide layer includes one or more of crystallized indium tin oxide (ITO), crystallized tungsten-doped indium oxide (IWO), crystallized cerium-doped indium oxide (ICO), crystallized molybdenum-doped indium oxide (IMO), crystallized indium oxide, annealed tin oxide, annealed fluorine-doped tin oxide (FTO), annealed antimony-doped tin oxide (ATO), and crystallized VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5. 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 .

[0035] In an optional embodiment, the material of the second transparent conductive oxide layer includes one or more of crystallized indium tin oxide (ITO), crystallized tungsten-doped indium oxide (IWO), crystallized cerium-doped indium oxide (ICO), crystallized molybdenum-doped indium oxide (IMO), crystallized indium oxide, annealed tin oxide, annealed fluorine-doped tin oxide (FTO), annealed antimony-doped tin oxide (ATO), and crystallized VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5: 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 .

[0036] In some embodiments, the material of the first sacrificial layer includes amorphous indium tin oxide (ITO), amorphous tungsten-doped indium oxide (IWO), amorphous cerium-doped indium oxide (ICO), amorphous molybdenum-doped indium oxide (IMO), amorphous indium oxide (In 2 O 3 ), amorphous zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), amorphous indium gallium zinc oxide (IGZO), amorphous nickel zinc oxide (NZO), zinc oxide, amorphous VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 The materials of these sacrificial layers have very low crystallinity or low density and poor acid resistance.

[0037] In an optional embodiment, the material of the second sacrificial layer includes amorphous indium tin oxide (ITO), amorphous tungsten-doped indium oxide (IWO), amorphous cerium-doped indium oxide (ICO), amorphous molybdenum-doped indium oxide (IMO), amorphous indium oxide (In 2 O 3 ), amorphous zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), amorphous indium gallium zinc oxide (IGZO), amorphous nickel zinc oxide (NZO), zinc oxide (ZnO), amorphous VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3The materials of these sacrificial layers have very low crystallinity or low density and poor acid resistance.

[0038] It should be noted that the TCO layer material and the sacrificial layer material in this application refer to the material that eventually forms the film layer, rather than the original material; for example, by annealing indium tin oxide to produce crystallized indium tin oxide to form the first TCO layer, the material of the first TCO layer is crystallized indium tin oxide. Among them, crystallized indium tin oxide (obtained after annealing) and amorphous indium tin oxide (not annealed) are different materials.

[0039] In some embodiments, the first transparent conductive oxide layer includes a plurality of sub-transparent conductive oxide layers stacked in sequence; The materials of each sub-transparent conductive oxide layer are different.

[0040] The first transparent conductive oxide layer includes a plurality of sub-transparent conductive oxide layers stacked in sequence, wherein the number of layers may be 2, 3, 4 or 5.

[0041] In an optional embodiment, the second transparent conductive oxide layer includes a plurality of sub-transparent conductive oxide layers stacked in sequence; wherein the materials of each sub-transparent conductive oxide layer are different. The material of the sub-transparent conductive oxide layer close to the silicon substrate is TCO containing indium, which can effectively reduce the resistance; the material of the sub-transparent conductive oxide layer far from the silicon substrate is TCO containing tin but not indium, which can reduce the production cost.

[0042] In some embodiments, in step S210, the method for preparing the first transparent conductive oxide layer includes: A transparent conductive oxide is deposited on the first surface, and annealed in an environment of 180-220° C. (eg, 180° C., 200° C., 220° C.) for 20-40 min (eg, 20 min, 30 min, 40 min) to form a first transparent conductive oxide layer.

[0043] In an optional embodiment, in step S220, the method for preparing the second transparent conductive oxide layer includes: Depositing a transparent conductive oxide on the second surface, and annealing the surface in an environment of 180-220° C. (eg, 180° C., 200° C., 220° C.) for 20-40 min (eg, 20 min, 30 min, 40 min) to form a second transparent conductive oxide layer.

[0044] Annealing the transparent conductive oxide in an environment of 180-220°C for 20-40 minutes can promote the crystallization of some TCOs (for example, TCOs containing indium), reduce the amorphous area, and thus improve the crystallinity of the material; or make the chemical composition distribution of some TCOs (for example, TCOs containing tin) more uniform and reduce the difference in local chemical composition; the first TCO layer formed after annealing has good corrosion resistance.

[0045] In some embodiments, in step S210, the method for preparing the first transparent conductive oxide layer includes: Depositing a first transparent conductive oxide on the first surface, and annealing in an environment of 180-220° C. for 20-40 minutes to form a first sub-transparent conductive oxide layer; Depositing a second transparent conductive oxide on the first sub-transparent conductive oxide layer, and annealing in an environment of 180-220° C. for 20-40 minutes to form a second sub-transparent conductive oxide layer; wherein the first transparent conductive oxide and the second transparent conductive oxide are different; The first transparent conductive oxide sub-layer and the second transparent conductive oxide sub-layer together constitute a first transparent conductive oxide layer.

[0046] In an optional embodiment, the first transparent conductive oxide and the second transparent conductive oxide may be annealed at one time to simultaneously form a first sub-transparent conductive oxide layer and a second sub-transparent conductive oxide layer; that is, the first transparent conductive oxide is deposited on the first surface, and the second transparent conductive oxide is deposited on the first transparent conductive oxide, and then annealed in an environment of 180-220° C. for 20-40 minutes to form a first sub-transparent conductive oxide layer and a second sub-transparent conductive oxide layer.

[0047] In an optional embodiment, the material of the first sub-transparent conductive oxide layer includes one or more of crystallized indium tin oxide (ITO), crystallized tungsten-doped indium oxide (IWO), crystallized cerium-doped indium oxide (ICO), crystallized molybdenum-doped indium oxide (IMO), crystallized indium oxide, and crystallized VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5. 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 ; The material of the second sub-transparent conductive oxide layer includes one or more of annealed tin oxide, annealed fluorine-doped tin oxide (FTO), and annealed antimony-doped tin oxide (ATO). In an optional embodiment, in step S220, the method for preparing the second transparent conductive oxide layer includes: Depositing a third transparent conductive oxide on the second surface, and annealing the layer in an environment of 180-220° C. for 20-40 minutes to form a third sub-transparent conductive oxide layer; depositing a fourth transparent conductive oxide on the third sub-transparent conductive oxide layer, and annealing the layer in an environment of 180-220° C. for 20-40 minutes to form a fourth sub-transparent conductive oxide layer; wherein the third transparent conductive oxide and the fourth transparent conductive oxide are different; The third transparent conductive oxide sub-layer and the fourth transparent conductive oxide sub-layer together constitute a second transparent conductive oxide layer.

[0048] In an optional embodiment, the third transparent conductive oxide and the fourth transparent conductive oxide may be annealed at one time to simultaneously form a third sub-transparent conductive oxide layer and a fourth sub-transparent conductive oxide layer; that is, the third transparent conductive oxide is deposited on the second surface, the fourth transparent conductive oxide is deposited on the third transparent conductive oxide, and then annealed in an environment of 180-220° C. for 20-40 minutes to form a third sub-transparent conductive oxide layer and a fourth sub-transparent conductive oxide layer.

[0049] In an optional embodiment, the material of the third sub-transparent conductive oxide layer includes one or more of crystallized indium tin oxide (ITO), crystallized tungsten-doped indium oxide (IWO), crystallized cerium-doped indium oxide (ICO), crystallized molybdenum-doped indium oxide (IMO), crystallized indium oxide, and crystallized VTTO; wherein the composition of VTTO is In with a mass ratio of 98.5:0.5:0.5:0.5. 2 O 3 :ZrO 2 :TiO 2 :Ga 2 O 3 ; The material of the fourth transparent conductive oxide sub-layer includes one or more of annealed tin oxide, annealed fluorine-doped tin oxide (FTO), and annealed antimony-doped tin oxide (ATO).

[0050] In some embodiments, after completely removing the first mask layer and the first metal seed layer located in the first non-metallic region, the method for preparing a solar cell further includes: S610: performing baking annealing on the first metal electrode and the first metal seed layer located in the first metal region; The annealing temperature is 180-220° C. and the annealing time is 20-40 min.

[0051] In an environment where the annealing temperature is 180-220°C (for example, 180°C, 200°C, 220°C) and the annealing time is 20-40min (for example, 20min, 30min, 40min), the metal material and the first metal seed layer located in the first metal area are baked and annealed, so that the metal material partially penetrates into the first sacrificial layer formed by the amorphous transparent conductive oxide, which is beneficial to the ohmic contact between the first TCO layer and the first metal electrode.

[0052] In an optional embodiment, after completely removing the second mask layer and the second metal seed layer located in the second non-metallic region, the method for preparing a solar cell further includes: S620: performing baking annealing on the second metal electrode and the second metal seed layer located in the second metal region; The annealing temperature is 180-220° C. and the annealing time is 20-40 min.

[0053] The second metal electrode and the second metal seed layer located in the second metal region are baked and annealed in an environment with an annealing temperature of 180-220°C (for example, 180°C, 200°C, 220°C) and an annealing time of 20-40min (for example, 20min, 30min, 40min), so as to improve the ohmic contact between the second TCO layer and the second metal electrode.

[0054] In some embodiments, the thickness of the first sacrificial layer is 3-8 nm; and / or The thickness of the first transparent conductive oxide layer is 60-100 nm.

[0055] When the thickness of the first sacrificial layer is 3-8nm, it can not only completely cover the first surface of the silicon substrate, effectively preventing the metal seed layer from directly contacting the silicon substrate, thereby avoiding the contamination of metal substances and silicon; but also, it is easier to remove the first sacrificial layer without affecting the electrical contact between the metal electrode and the TCO layer. Specifically, the thickness of the first sacrificial layer can be 3nm, 5nm or 8nm.

[0056] When the thickness of the first transparent conductive oxide layer is 60-100 nm, the first TCO layer has not only good light transmittance but also good conductivity to collect and transport carriers. Specifically, the thickness of the first transparent conductive oxide layer can be 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0057] In an optional embodiment, the thickness of the second sacrificial layer is 3-8 nm; specifically, the thickness of the second sacrificial layer can be 3 nm, 5 nm or 8 nm. In other embodiments, the thickness of the second transparent conductive oxide layer is 60-100 nm; specifically, the thickness of the second transparent conductive oxide layer can be 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0058] In some embodiments, the material of the first metal electrode includes one or both of copper and tin; and / or The material of the first metal seed layer includes one or more of copper, nickel and aluminum.

[0059] In an optional embodiment, the material of the second metal electrode includes one or both of copper and tin; and / or the material of the second metal seed layer includes one or more of copper, nickel and aluminum.

[0060] Metal materials such as copper and tin not only have good electrical conductivity and low contact resistance with the TCO layer, but also have lower cost than silver. Forming metal electrodes (first metal electrodes and / or second metal electrodes) from copper and / or tin can reduce the cost of solar cells. Metal materials can be electroplated by horizontal electroplating, rack plating, tank electroplating, etc. to form metal electrodes.

[0061] Materials such as copper, nickel, and aluminum have good compatibility with metal electrodes and can provide a more stable attachment base for subsequent electroplating to form metal electrodes; moreover, materials such as copper, nickel, and aluminum have lower electrical conductivity and lower cost, which helps to reduce resistance and improve current transmission efficiency, and also helps to achieve the goal of cost reduction.

[0062] In an optional embodiment, the thickness of the first metal seed layer and the second metal seed layer are respectively and independently 80-120 nm.

[0063] In an optional embodiment, a KOH solution (5%) is used at 30-50° C. for 2 min to remove the first mask layer and / or the second mask layer; a sulfuric acid solution (2%) + H 2 O 2 The solution (1%) is kept at room temperature for 2 minutes to remove the first metal seed layer in the first non-metallic area and / or the second metal seed layer in the second non-metallic area. When removing the seed layer, the sacrificial layer will be partially or completely removed, which not only ensures that the metal seed layer in the non-metallic area is completely removed, but also because the material of the sacrificial layer is non-acid-resistant TCO, it has been corroded and removed, which reduces the difficulty of removal and saves process time.

[0064] The mask layer (the first mask layer and / or the second mask layer) may be formed by screen printing, photoresist wet film, direct attachment of dry film, inkjet printing of hot melt wax, or the like.

[0065] In an alternative embodiment, the first sacrificial layer completely covers the first surface having the first transparent conductive oxide layer.

[0066] In an alternative embodiment, the second sacrificial layer completely covers the second surface having the second transparent conductive oxide layer.

[0067] In actual production, during the process of forming the TCO layer, there are sometimes blank areas without TCO layer on the silicon substrate (areas without TCO blocking), and the blank areas are prone to diffusion contamination of copper and silicon. When there are blank areas without TCO layer on the silicon substrate, the sacrificial layer can only cover the TCO layer, or fill the blank areas without TCO layer at the same time. When the first sacrificial layer completely covers the first surface with the first transparent conductive oxide layer, the first sacrificial layer can fill the blank areas without TCO layer, as a barrier layer for the first metal seed layer, to prevent the metal substance of the first metal seed layer from entering the silicon substrate during the preparation process, to avoid diffusion contamination of metal substance and silicon, thereby effectively avoiding the problem of recombination and leakage of positive and negative electrodes, and improving the electrical performance and stability of solar cells. Similarly, when the second sacrificial layer completely covers the second surface with the second transparent conductive oxide layer, the second sacrificial layer can also fill the blank areas without TCO layer, to avoid diffusion contamination of metal substance and silicon, thereby improving the electrical performance and stability of solar cells.

[0068] An embodiment of the present application further provides a solar cell formed by the solar cell preparation method of any of the above embodiments.

[0069] 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.

[0070] Example 1 The structure of the solar cell of embodiment 1 comprises: A silicon substrate (N-type silicon substrate), the silicon substrate comprising a first surface and a second surface arranged opposite to each other; An intrinsic amorphous silicon layer, an N-type doped microcrystalline silicon layer, and a first transparent conductive oxide layer are located on the first surface and are sequentially stacked in a direction away from the silicon substrate; A first sacrificial layer, a first metal seed layer, and a first metal electrode are located in the first metal region of the first transparent conductive oxide layer and are sequentially stacked in a direction away from the silicon substrate; An intrinsic amorphous silicon layer, a P-type doped microcrystalline silicon layer, and a second transparent conductive oxide layer are located on the second surface and are sequentially stacked in a direction away from the silicon substrate; The second metal region is located in the second transparent conductive oxide layer, and includes a second sacrificial layer, a second metal seed layer, and a second metal electrode which are sequentially stacked in a direction away from the silicon substrate.

[0071] The method for preparing a solar cell of embodiment 1 comprises: Step S110a: providing a silicon substrate (N-type silicon substrate), wherein the silicon substrate comprises a first surface and a second surface that are oppositely disposed; Step S120a: forming an intrinsic amorphous silicon layer on both the first surface and the second surface; Step S130a: forming an N-type doped microcrystalline silicon layer on the intrinsic amorphous silicon layer located on the first surface, and forming a P-type doped microcrystalline silicon layer on the intrinsic amorphous silicon layer located on the second surface; Step S210a: depositing VTTO on the N-type doped microcrystalline silicon layer, and annealing the layer in an environment of 200° C. for 30 minutes to crystallize the VTTO, thereby generating crystallized VTTO to form a first transparent conductive oxide layer of 100 nm; Step S220a: depositing VTTO on the P-type doped microcrystalline silicon layer, and annealing the layer in an environment of 200° C. for 30 minutes to crystallize the VTTO, thereby generating crystallized VTTO to form a second transparent conductive oxide layer of 100 nm; Step S230a: depositing amorphized VTTO on the first transparent conductive oxide layer without high temperature annealing to form a first sacrificial layer with a thickness of 5 nm; Step S240a: depositing amorphized VTTO on the second transparent conductive oxide layer without high temperature annealing to form a second sacrificial layer with a thickness of 5 nm; Step S250a: forming a first metal seed layer on the first sacrificial layer; Step S260a: forming a second metal seed layer on the second sacrificial layer; Step S310a: forming a patterned first mask layer on the first metal seed layer, wherein the first mask layer covers the first metal seed layer located in the first non-metal region and exposes the first metal seed layer located in the first metal region; Step S320a: forming a patterned second mask layer on the second metal seed layer, wherein the second mask layer covers the second metal seed layer located in the second non-metal region and exposes the second metal seed layer located in the second metal region; Step S410a: using an electroplating process to deposit copper on the first metal seed layer located in the first metal region to form a first metal electrode; Step S420a: using an electroplating process to deposit copper on the second metal seed layer located in the second metal region to form a second metal electrode; Step S510a: Use KOH solution (concentration of 5%) to completely remove the first mask layer and the second mask layer, and use sulfuric acid (2%) + H 2 O 2 (1%) completely remove the first metal seed layer in the first non-metal region and the second metal seed layer in the second non-metal region; Step S610a: performing baking annealing on the first metal electrode, the second metal electrode, the first metal seed layer located in the first metal region, and the second metal seed layer located in the second metal region; wherein the annealing temperature is 200° C. and the annealing time is 30 min.

[0072] Example 2 The structure of the solar cell of Example 2 is similar to that of the solar cell of Example 1, and the only difference is that the solar cell of Example 2 does not have the second sacrificial layer.

[0073] The solar cell of Example 2 is prepared by a preparation method similar to that of Example 1, except that the preparation method of Example 2 does not have step S240a, and step S260a is: forming a second metal seed layer on the second transparent conductive oxide layer.

[0074] Example 3 The structure of the solar cell of Example 3 is similar to that of the solar cell of Example 1, except that, in the solar cell of Example 3, the first transparent conductive oxide layer includes a first sub-transparent conductive oxide layer and a second sub-transparent conductive oxide layer, and the second transparent conductive oxide layer includes a third sub-transparent conductive oxide layer and a fourth sub-transparent conductive oxide layer.

[0075] The solar cell of Example 3 is prepared by a preparation method similar to that of Example 1, except that step S210a of Example 3 is: depositing VTTO on the N-type doped microcrystalline silicon layer, and depositing SnO 2 The SnO layer is deposited on the VTTO and annealed at 200°C for 30 minutes to crystallize the VTTO and generate a crystallized VTTO to form a 40nm first sub-transparent conductive oxide layer. 2 After annealing, a second sub-transparent conductive oxide layer of 40 nm is formed; the first sub-transparent conductive oxide layer and the second sub-transparent conductive oxide layer together constitute a first transparent conductive oxide layer; Step S220a of the third embodiment is: depositing VTTO on the P-type doped microcrystalline silicon layer, 2 The SnO layer is deposited on the VTTO and annealed at 200°C for 30 minutes to crystallize the VTTO and generate a crystallized VTTO to form a 40nm third sub-transparent conductive oxide layer.2 After annealing treatment, a fourth sub-transparent conductive oxide layer with a thickness of 40 nm is formed; the third sub-transparent conductive oxide layer and the fourth sub-transparent conductive oxide layer together constitute a second transparent conductive oxide layer.

[0076] In order to more clearly illustrate the technical effects of the embodiments of the present application, the present application also points out the specific structures and preparation methods of the solar cells of Comparative Examples 1 and 2.

[0077] Comparative Example 1 The structure of the solar cell of Comparative Example 1 is similar to that of the solar cell of Example 1, except that the solar cell of Comparative Example 1 does not have the first sacrificial layer and the second sacrificial layer.

[0078] The solar cell of Comparative Example 1 is prepared by a preparation method similar to that of Example 1, except that the preparation method of the solar cell of Comparative Example 1 does not include step S230a and step S240a; Furthermore, step S250a is: forming a first metal seed layer on the first TCO layer; Step S260a is: forming a second metal seed layer on the second TCO layer.

[0079] Comparative Example 2 The structure of the solar cell of Comparative Example 2 is similar to that of the solar cell of Example 3, except that the solar cell of Comparative Example 1 does not have the first sacrificial layer and the second sacrificial layer.

[0080] The solar cell of Comparative Example 2 is prepared by a preparation method similar to that of Example 3, except that the preparation method of the solar cell of Comparative Example 1 does not include step S230a and step S240a; Furthermore, step S250a is: forming a first metal seed layer on the first TCO layer; Step S260a is: forming a second metal seed layer on the second TCO layer.

[0081] The present application also manufactures the solar cells (210*105mm cell sheets) in Examples 1 to 3 and Comparative Examples 1 to 2 into corresponding photovoltaic modules, and conducts performance tests to obtain the conversion efficiency Eff, short-circuit current Isc, open-circuit voltage Voc, and fill factor FF of the corresponding photovoltaic modules. The relevant test results are shown in Table 1.

[0082] Table 1

[0083] It can be seen from the data in Table 1 that, compared with Comparative Example 1 (relative to Example 1, which does not have the first sacrificial layer and the second sacrificial layer), the short-circuit current, open-circuit voltage, fill factor and conversion efficiency of the photovoltaic modules made of the solar cells of Examples 1 to 2 of the present application are significantly improved; compared with Comparative Example 2 (relative to Example 3, which does not have the first sacrificial layer and the second sacrificial layer), the short-circuit current, open-circuit voltage, fill factor and conversion efficiency of the photovoltaic modules made of the solar cells of Example 3 are significantly improved.

[0084] In summary, in the embodiment of the present application, a first sacrificial layer is provided between the first transparent conductive oxide (TCO) layer and the first metal seed layer, which reduces the corrosion of the first metal seed layer to the first TCO layer and reduces the optical and electrical losses. Moreover, the first transparent conductive oxide layer has a good corrosion resistance; and the first sacrificial layer is easily removed by corrosion, which is conducive to completely removing the first metal seed layer in the first non-metallic region, thereby reducing the shading loss and improving the open circuit voltage and photoelectric conversion rate of the solar cell.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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: Providing a silicon substrate, the silicon substrate comprising a first surface and a second surface arranged opposite to each other; forming a first transparent conductive oxide layer, a first sacrificial layer, and a first metal seed layer in sequence on the first surface; forming a patterned first mask layer on the first metal seed layer, wherein the first mask layer covers the first metal seed layer located in the first non-metal region and exposes the first metal seed layer located in the first metal region; Depositing a metal material on the first metal seed layer located in the first metal region by an electroplating process to form a first metal electrode; Completely removing the first mask layer and the first metal seed layer located in the first non-metallic area; Wherein, the first transparent conductive oxide layer is an acid-resistant transparent conductive oxide layer; The first sacrificial layer is a non-acid-resistant transparent conductive oxide layer.

2. The method for preparing a solar cell according to claim 1, characterized in that: Also includes: forming a second transparent conductive oxide layer, a second sacrificial layer, and a second metal seed layer in sequence on the second surface; forming a patterned second mask layer on the second metal seed layer, wherein the second mask layer covers the second metal seed layer located in the second non-metal region and exposes the second metal seed layer located in the second metal region; Depositing a metal material on the second metal seed layer located in the second metal region by an electroplating process to form a second metal electrode; Completely removing the second mask layer and the second metal seed layer in the second non-metal region; Wherein, the second transparent conductive oxide layer is an acid-resistant transparent conductive oxide layer; and the second sacrificial layer is a non-acid-resistant transparent conductive oxide layer.

3. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The material of the first transparent conductive oxide layer is an annealed transparent conductive oxide containing indium and / or tin.

4. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The material of the first transparent conductive oxide layer includes one or more of crystallized indium tin oxide, crystallized tungsten-doped indium oxide, crystallized cerium-doped indium oxide, crystallized molybdenum-doped indium oxide, crystallized indium oxide, annealed tin oxide, annealed fluorine-doped tin oxide, annealed antimony-doped tin oxide, and crystallized VTTO; wherein the composition of VTTO is In2O3:ZrO2:TiO2:Ga2O3 with a mass ratio of 98.5:0.5:0.5:0.

5.

5. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The material of the first sacrificial layer includes one or more of amorphous indium tin oxide, amorphous tungsten-doped indium oxide, amorphous cerium-doped indium oxide, amorphous molybdenum-doped indium oxide, amorphous indium oxide, amorphous zinc-doped indium oxide, aluminum-doped zinc oxide, amorphous indium gallium zinc oxide, amorphous nickel zinc oxide, zinc oxide, and amorphous VTTO; wherein the composition of VTTO is In2O3:ZrO2:TiO2:Ga2O3 with a mass ratio of 98.5:0.5:0.5:0.

5.

6. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The first transparent conductive oxide layer comprises a plurality of sub-transparent conductive oxide layers stacked in sequence; The materials of each sub-transparent conductive oxide layer are different.

7. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The method for preparing the first transparent conductive oxide layer comprises: A transparent conductive oxide is deposited on the first surface, and annealed in an environment of 180-220° C. for 20-40 minutes to form the first transparent conductive oxide layer.

8. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The method for preparing the first transparent conductive oxide layer comprises: Depositing a first transparent conductive oxide on the first surface, and annealing in an environment of 180-220° C. for 20-40 minutes to form a first sub-transparent conductive oxide layer; Depositing a second transparent conductive oxide on the first sub-transparent conductive oxide layer, and annealing in an environment of 180-220° C. for 20-40 minutes to form a second sub-transparent conductive oxide layer; wherein the first transparent conductive oxide and the second transparent conductive oxide are different; The first transparent conductive oxide layer and the second transparent conductive oxide layer together constitute the first transparent conductive oxide layer.

9. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: After completely removing the first mask layer and the first metal seed layer located in the first non-metallic region, the method for preparing a solar cell further includes: Performing baking annealing on the first metal electrode and the first metal seed layer located in the first metal region; The annealing temperature is 180-220° C. and the annealing time is 20-40 min.

10. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The thickness of the first sacrificial layer is 3-20 nm; and / or The thickness of the first transparent conductive oxide layer is 60-100 nm.

11. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The material of the first metal electrode includes one or both of copper and tin; and / or The material of the first metal seed layer includes one or more of copper, nickel and aluminum.

12. The method for preparing a solar cell according to any one of claims 1 to 2, characterized in that: The first sacrificial layer completely covers the first surface having the first transparent conductive oxide layer.

13. A solar cell, characterized in that: The solar cell is formed by the method for preparing the solar cell according to any one of claims 1 to 12.

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