Electrode and preparation method thereof, solar cell

Abstract

The present application relates to an electrode and a preparation method thereof, and a solar cell. The preparation method of the electrode of the present application includes: providing a substrate; preparing a first metal layer on the surface of the substrate, the material of the first metal layer includes copper, and the preparation method of the first metal layer includes physical vapor deposition; preparing a second metal layer on the surface of the first metal layer, the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy; preparing a third metal layer on the surface of the second metal layer, the material of the third metal layer includes copper, and the preparation method of the third metal layer includes physical vapor deposition; preparing a fourth metal layer on the surface of the third metal layer, the material of the fourth metal layer includes copper, and the preparation method of the fourth metal layer includes electroplating.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to an electrode and a preparation method thereof, and a solar cell. Background Art

[0002] Screen printing silver paste to prepare silver electrodes is currently the mainstream method for preparing solar cell electrodes, but the high price of low-temperature silver paste limits the cost reduction of silicon heterojunction solar cells. Electroplating copper electrodes is one of the feasible solutions to replace silver electrodes to reduce the cost of solar cells.

[0003] The traditional preparation of electroplated copper electrodes first involves physical vapor deposition of a copper seed layer on a transparent metal oxide film, coating the copper seed layer with a photosensitive adhesive film, and then electroplating copper after forming a pattern through ultraviolet exposure and development. However, the photosensitive adhesive film on the surface of the electroplated copper in the copper electrode prepared by this method is prone to remain, resulting in holes between the electroplated copper layer and the copper seed layer, which in turn causes a large contact resistance and a low conversion efficiency of the solar cell. Summary of the invention

[0004] Based on this, it is necessary to provide an electrode and a preparation method thereof, and a solar cell. The electrode preparation method has a high bonding force between the electrode layers, which can effectively reduce the contact resistance between the electrode and the solar cell, thereby improving the conversion efficiency of the solar cell.

[0005] In a first aspect, the present application provides a method for preparing an electrode, comprising:

[0006] providing a substrate;

[0007] Preparing a first metal layer on the surface of the substrate, wherein the material of the first metal layer includes copper, and the preparation method of the first metal layer includes physical vapor deposition;

[0008] Preparing a second metal layer on the surface of the first metal layer, wherein the material of the second metal layer comprises at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy;

[0009] Preparing a third metal layer on the surface of the second metal layer, wherein the material of the third metal layer includes copper, and the preparation method of the third metal layer includes physical vapor deposition;

[0010] A fourth metal layer is prepared on the surface of the third metal layer. The material of the fourth metal layer includes copper. The preparation method of the fourth metal layer includes electroplating.

[0011] In some embodiments, the thickness of the first metal layer is 10 nm to 200 nm.

[0012] In some embodiments, the thickness of the second metal layer is 10 nm to 200 nm.

[0013] In some embodiments, the thickness of the third metal layer is 10 nm to 200 nm.

[0014] In some embodiments, the thickness of the fourth metal layer is 5 μm-20 μm.

[0015] In some embodiments, before forming the fourth metal layer on the surface of the third metal layer, the method further comprises:

[0016] The third metal layer is first pickled to remove oxide on the surface of the third metal layer.

[0017] In some embodiments, after forming a fourth metal layer on the surface of the third metal layer, the method further comprises:

[0018] Preparing a mask layer on the surface of the fourth metal layer;

[0019] Performing a first etching on the fourth metal layer and the third metal layer exposed from the mask layer using a first etching solution;

[0020] Performing a second etching on the second metal layer exposed from the mask layer using a second etching solution;

[0021] Performing a third etching on the first metal layer exposed from the mask layer using a third etching solution;

[0022] The mask layer is removed.

[0023] In some embodiments, the first etching solution includes an acidic etching solution or an alkaline etching solution, the acidic etching solution includes copper chloride with mass volume concentrations of 120g / L~180g / L and hydrochloric acid with mass volume concentrations of 30g / L~70g / L, and the alkaline etching solution includes copper chloride with mass volume concentrations of 120g / L~180g / L and ammonia water with mass volume concentrations of 50g / L~100g / L.

[0024] In some embodiments, the second etching solution includes 5% to 15% by mass of hydrogen peroxide and 1% to 5% by mass of phosphoric acid, and the pH value of the second etching solution is 1 to 3.

[0025] In some embodiments, the third etching solution includes 0.1% to 0.5% by mass of sulfuric acid and 1% to 3% by mass of sodium persulfate, and the pH range of the third etching solution is 1 to 3.

[0026] In some embodiments, the first etching temperature is 30°C to 50°C.

[0027] In some embodiments, the first etching time is 60s~120s.

[0028] In some embodiments, the second etching temperature is 30°C-50°C.

[0029] In some embodiments, the second etching time is 10s to 60s.

[0030] In some embodiments, the temperature of the third etching is 20°C-30°C.

[0031] In some embodiments, the third etching time is 10s~60s.

[0032] In some embodiments, before preparing a mask layer on the surface of the fourth metal layer, the method further includes:

[0033] The fourth metal layer is subjected to a second acid wash to remove oxide on the surface of the fourth metal layer.

[0034] In some embodiments, after removing the mask layer, the method further includes:

[0035] A fifth metal layer is prepared on the surface of the fourth metal layer, and a material of the fifth metal layer includes at least one of silver, silver alloy, tin and tin alloy.

[0036] In some embodiments, after forming a fifth metal layer on the surface of the fourth metal layer, the method further comprises:

[0037] The electrode is subjected to an annealing treatment.

[0038] In some embodiments, the annealing treatment is performed at a temperature of 100° C. to 150° C.

[0039] In some embodiments, the holding time of the annealing treatment is 0.5h~3h.

[0040] In a second aspect, the present application provides an electrode, which is prepared by any of the above-mentioned methods for preparing an electrode, comprising:

[0041] A first metal layer, a second metal layer, a third metal layer and a fourth metal layer are stacked in sequence;

[0042] The material of the first metal layer includes copper; the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy; the material of the third metal layer includes copper; the material of the fourth metal layer includes copper.

[0043] In some embodiments, the electrode includes a fifth metal layer located on a surface of the fourth metal layer, and a material of the fifth metal layer includes at least one of silver, a silver alloy, tin, and a tin alloy.

[0044] In a third aspect, the present application provides a solar cell, comprising: an electrode prepared by the method for preparing an electrode described in any one of the above, or an electrode described in any one of the above.

[0045] In the above-mentioned method for preparing the electrode, a first metal layer is prepared on the surface of the substrate, the material of the first metal layer includes copper, the method for preparing the first metal layer includes physical vapor deposition, and the first metal layer serves as a seed layer. A second metal layer is prepared on the surface of the first metal layer, the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy, the second metal layer serves as a protective layer for the first metal layer, and can prevent damage to the first metal layer in subsequent etching, and the second metal layer and the first metal layer have a good bonding effect. A third metal layer is prepared on the surface of the second metal layer, the material of the third metal layer includes copper, the method for preparing the third metal layer includes physical vapor deposition, the third metal layer serves as a protective layer for the second metal layer, and can prevent the surface of the second metal layer from being oxidized, and the third metal layer and the second metal layer have a good bonding effect. A fourth metal layer is prepared on the surface of the third metal layer. The material of the fourth metal layer includes copper. The preparation method of the fourth metal layer includes electroplating. The fourth metal layer is used as a thickened copper metal layer and as a current conducting layer. A thicker copper metal layer can be prepared in a shorter time through electroplating. The fourth metal layer has a better bonding effect with the third metal layer. The preparation method of the electrode avoids directly coating the copper seed layer with a photosensitive adhesive film, and can reduce the contact resistance caused by the holes between the electroplated copper and the copper seed layer due to the residual photosensitive adhesive film. At the same time, the bonding force between the layers of the electrode prepared by the preparation method of the electrode is higher, which can effectively reduce the contact resistance between the electrode and the solar cell, thereby improving the conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of a process for preparing an electrode provided in one embodiment of the present application;

[0047] Figure 2 A schematic flow chart of a method for preparing an electrode provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0050] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] Reference Figure 1 , an embodiment of the present application provides a method for preparing an electrode, comprising:

[0054] S110: providing a substrate.

[0055] S120: preparing a first metal layer on the surface of the substrate, wherein the material of the first metal layer includes copper, and the preparation method of the first metal layer includes physical vapor deposition.

[0056] S130: Preparing a second metal layer on the surface of the first metal layer, wherein a material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy.

[0057] S140: preparing a third metal layer on the surface of the second metal layer, wherein the material of the third metal layer includes copper, and the preparation method of the third metal layer includes physical vapor deposition.

[0058] S150: preparing a fourth metal layer on the surface of the third metal layer, wherein the material of the fourth metal layer includes copper, and the preparation method of the fourth metal layer includes electroplating.

[0059] In the above-mentioned method for preparing the electrode, a first metal layer is prepared on the surface of the substrate, the material of the first metal layer includes copper, the method for preparing the first metal layer includes physical vapor deposition, and the first metal layer serves as a seed layer. A second metal layer is prepared on the surface of the first metal layer, the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy, the second metal layer serves as a protective layer for the first metal layer, and can prevent damage to the first metal layer in subsequent etching, and the second metal layer and the first metal layer have a good bonding effect. A third metal layer is prepared on the surface of the second metal layer, the material of the third metal layer includes copper, the method for preparing the third metal layer includes physical vapor deposition, the third metal layer serves as a protective layer for the second metal layer, and can prevent the surface of the second metal layer from being oxidized, and the third metal layer and the second metal layer have a good bonding effect. A fourth metal layer is prepared on the surface of the third metal layer. The material of the fourth metal layer includes copper. The preparation method of the fourth metal layer includes electroplating. The fourth metal layer is used as a thickened copper metal layer and as a current conducting layer. A thicker copper metal layer can be prepared in a shorter time through electroplating. The fourth metal layer has a better bonding effect with the third metal layer. The preparation method of the electrode avoids directly coating a photosensitive adhesive film on the copper seed layer, and can reduce the poor contact caused by the holes between the electroplated copper and the copper seed layer. At the same time, the bonding force between the layers of the electrode prepared by the preparation method of the electrode is relatively high, which can effectively reduce the contact resistance between the electrode and the solar cell, thereby improving the conversion efficiency of the solar cell.

[0060] In one embodiment, the substrate is a solar cell preform. The solar cell preform includes a silicon substrate having a first surface and a second surface arranged opposite to each other, an n-type intrinsic amorphous silicon layer, an n-type doped layer and a first transparent conductive layer stacked in sequence on the first surface, and a p-type intrinsic amorphous silicon layer, a p-type doped layer and a second transparent conductive layer stacked in sequence on the second surface. It can be understood that the method for preparing the electrode in this embodiment is to prepare the electrode on the first transparent conductive layer and / or the second transparent conductive layer.

[0061] In some embodiments, the second metal layer is prepared by a method comprising physical vapor deposition and / or chemical deposition.

[0062] In some embodiments, before preparing the first metal layer on the surface of the substrate, the solar cell pre-finished product is also pre-cleaned. The pre-cleaning includes: using a degreasing solution to degrease the solar cell pre-finished product, the degreasing treatment time is 10s~200s, and the temperature is 20℃~40℃. The degreasing solar cell pre-finished product is washed at least twice, the water washing temperature is 20℃~40℃, the water washing time is 1min~3min, and the water washing is deionized water washing. The washed solar cell pre-finished product is dried, the drying temperature is 100℃~200℃, and the time is 5min~20min.

[0063] In some embodiments, the thickness of the first metal layer is 10nm to 200nm. When the thickness of the first metal layer is too small, the resistance value is too large. When the thickness of the first metal layer is too large, the preparation cost is high. Optionally, the thickness of the first metal layer is 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm.

[0064] In some embodiments, the thickness of the second metal layer is 10nm to 200nm. When the thickness of the second metal layer is too small, the resistance value is too large. When the thickness of the second metal layer is too large, the preparation cost is high. Optionally, the thickness of the second metal layer is 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm.

[0065] In some embodiments, the thickness of the third metal layer is 10nm to 200nm. When the thickness of the third metal layer is too small, the resistance value is too large. When the thickness of the third metal layer is too large, the preparation cost is high. Optionally, the thickness of the third metal layer is 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm or 200nm.

[0066] In some embodiments, the thickness of the fourth metal layer is 5 μm to 20 μm. Within the thickness range of the fourth metal layer, the fourth metal layer has a good conductive effect. Optionally, the thickness of the fourth metal layer is 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm or 20 μm.

[0067] In some embodiments, forming the fourth metal layer on the surface of the third metal layer includes: forming the fourth metal layer by electroplating with a copper plating solution.

[0068] In some embodiments, the copper plating solution includes 50 g / L to 200 g / L copper sulfate, 100 g / L to 200 g / L sulfuric acid, and 30 ppm to 100 ppm chloride ions.

[0069] In some embodiments, before forming the fourth metal layer on the surface of the third metal layer, the method further includes: performing a first acid wash on the third metal layer to remove oxide on the surface of the third metal layer.

[0070] The oxide on the surface of the third metal layer is removed by the first acid washing, which has an activation effect on the third metal layer and can increase the bonding force between the fourth metal layer and the third metal layer.

[0071] In some embodiments, the first acid wash uses a first acid wash solution, and the first acid wash solution includes at least one of sulfuric acid and hydrochloric acid.

[0072] In some embodiments, the mass percentage of the solute in the first acid wash solution is 2% to 10%. Optionally, the mass percentage of the solute in the first acid wash solution is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0073] In some embodiments, the first pickling time is 10s to 60s. Optionally, the first pickling time is 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s or 60s.

[0074] In some embodiments, the temperature of the first acid wash is 20° C. to 30° C. Optionally, the temperature of the first acid wash is 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. or 30° C.

[0075] In some embodiments, the first pickling is performed by immersing the substrate after the third metal layer is formed into a first pickling solution for the first pickling.

[0076] In some embodiments, after preparing the fourth metal layer on the surface of the third metal layer, the method further includes: preparing a mask layer on the surface of the fourth metal layer; using a first etching solution to perform a first etching on the fourth metal layer and the third metal layer exposed to the mask layer; using a second etching solution to perform a second etching on the second metal layer exposed to the mask layer; using a third etching solution to perform a third etching on the first metal layer exposed to the mask layer; and removing the mask layer.

[0077] It is understood that the mask layer includes a photosensitive adhesive film, and the patterning of the electrode can be achieved through the above steps. When performing the first etching, the second metal layer can protect the first metal layer to prevent the first metal layer from being damaged. When performing the second etching, a selective etching solution that only etches the second metal layer can be used to prevent the first metal layer from being damaged, and then the first metal layer can be etched.

[0078] In some embodiments, the first etching solution includes an acidic etching solution or an alkaline etching solution, the acidic etching solution includes copper chloride with mass volume concentrations of 120g / L~180g / L and hydrochloric acid with mass volume concentrations of 30g / L~70g / L, and the alkaline etching solution includes copper chloride with mass volume concentrations of 120g / L~180g / L and ammonia water with mass volume concentrations of 50g / L~100g / L.

[0079] Optionally, the mass volume concentration of cupric chloride is 120g / L, 125g / L, 130g / L, 135g / L, 140g / L, 145g / L, 150g / L, 155g / L, 160g / L, 165g / L, 170g / L, 175g / L or 180g / L.

[0080] Optionally, the mass volume concentration of hydrochloric acid is 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, 55g / L, 60g / L, 65g / L or 70g / L.

[0081] Optionally, the mass volume concentration of aqueous ammonia is 50g / L, 55g / L, 60g / L, 65g / L, 70g / L, 75g / L, 80g / L, 85g / L, 90g / L or 100g / L.

[0082] In some embodiments, the second etching solution includes 5% to 15% by mass of hydrogen peroxide and 1% to 5% by mass of phosphoric acid, and the pH value of the second etching solution is 1 to 3.

[0083] In some embodiments, the third etching solution includes 0.1% to 0.5% by mass of sulfuric acid and 1% to 3% by mass of sodium persulfate, and the pH range of the third etching solution is 1 to 3.

[0084] In some embodiments, the temperature of the first etching is 30° C. to 50° C. Optionally, the temperature of the first etching is 30° C., 32° C., 34° C., 36° C., 38° C., 40° C., 42° C., 44° C., 46° C., 48° C., or 50° C.

[0085] In some embodiments, the first etching time is 60s to 120s. Optionally, the first etching time is 60s, 65s, 70s, 75s, 80s, 85s, 90s, 95s, 100s, 105s, 110s, 115s or 120s.

[0086] In some embodiments, the temperature of the second etching is 30° C. to 50° C. Optionally, the temperature of the second etching is 30° C., 32° C., 34° C., 36° C., 38° C., 40° C., 42° C., 44° C., 46° C., 48° C., or 50° C.

[0087] In some embodiments, the second etching time is 10s to 60s. Optionally, the second etching time is 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s or 60s.

[0088] In some embodiments, the temperature of the third etching is 20° C. to 30° C. Optionally, the temperature of the third etching is 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. or 30° C.

[0089] In some embodiments, the third etching time is 10s to 60s. Optionally, the third etching time is 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s or 60s.

[0090] In some embodiments, before preparing the mask layer on the surface of the fourth metal layer, the method further includes: performing a second acid wash on the fourth metal layer to remove oxide on the surface of the fourth metal layer.

[0091] The oxide on the surface of the fourth metal layer is removed by the second pickling, so that the bonding force between the fourth metal layer and the mask layer can be enhanced.

[0092] In some embodiments, the second acid wash uses a second acid wash solution, and the second acid wash solution includes at least one of sulfuric acid and hydrochloric acid.

[0093] In some embodiments, the mass percentage of the solute in the second acid wash solution is 2% to 10%. Optionally, the mass percentage of the solute in the second acid wash solution is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0094] In some embodiments, the second pickling time is 10s to 60s. Optionally, the second pickling time is 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s or 60s.

[0095] In some embodiments, the temperature of the second acid wash is 20° C. to 30° C. Optionally, the temperature of the second acid wash is 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. or 30° C.

[0096] In some embodiments, the second pickling is performed by immersing the substrate after the fourth metal layer is formed into a second pickling solution for the second pickling.

[0097] In some embodiments, removing the mask layer includes: performing alkaline washing on the mask layer using an alkaline washing solution, wherein the solute of the alkaline washing solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

[0098] In some embodiments, the mass percentage of the solute in the alkali wash solution is 10% to 20%. Optionally, the mass percentage of the solute in the alkali wash solution is 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0099] In some embodiments, the alkali washing time is 20s to 60s. Optionally, the alkali washing time is 20s, 25s, 30s, 35s, 40s, 45s, 50s or 60s.

[0100] In some embodiments, the temperature of the alkali wash is 30° C. to 50° C. Alternatively, the temperature of the alkali wash is 30° C., 32° C., 34° C., 36° C., 38° C., 40° C., 42° C., 44° C., 46° C., 48° C. or 50° C.

[0101] In some embodiments, removing the mask layer is performed by immersing the film after the third etching in an alkaline cleaning solution to remove the mask layer.

[0102] In some embodiments, after removing the mask layer, the method further includes: preparing a fifth metal layer on the surface of the fourth metal layer, wherein the material of the fifth metal layer includes at least one of silver, silver alloy, tin and tin alloy. The fifth metal layer is used as a welding layer and a protective layer for welding between different electrodes and protecting the underlying metal layers.

[0103] In some embodiments, the preparation method of the fifth metal layer includes chemical deposition. By preparing the fifth metal layer by chemical deposition, the entire device can be directly chemically deposited, and the fifth metal layer is only deposited on the surface of the fourth metal layer.

[0104] In some embodiments, the method for preparing the fifth metal layer includes: preparing the fifth metal layer using a chemical tin plating solution.

[0105] In some embodiments, the chemical tin plating solution includes a tin plating additive and 10 g / L to 30 g / L of tin sulfate.

[0106] In some embodiments, the method for preparing the fifth metal layer includes: preparing the fifth metal layer using a chemical silver plating solution.

[0107] In some embodiments, the chemical silver plating solution includes a silver plating additive and 10 g / L to 40 g / L of silver nitrate.

[0108] In some embodiments, the thickness of the fifth metal layer is 0.5 μm to 1 μm. Optionally, the thickness of the fifth metal layer is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm.

[0109] In some embodiments, after the fifth metal layer is formed on the surface of the fourth metal layer, the method further includes: annealing the electrode. Annealing the electrode can further enhance the bonding force between the layers and ensure good interface contact between the layers.

[0110] In some embodiments, the temperature of the annealing treatment is 100° C. to 150° C. Optionally, the temperature of the annealing treatment is 100° C., 105° C., 110° C., 115° C., 120° C., 125° C., 130° C., 135° C., 140° C., or 150° C.

[0111] In some embodiments, the holding time of the annealing treatment is 0.5 h to 3 h. Optionally, the holding time of the annealing treatment is 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0112] Reference Figure 2 In some embodiments, the method for preparing an electrode comprises:

[0113] S210: providing a substrate.

[0114] S220: preparing a first metal layer on the surface of the substrate, wherein the material of the first metal layer includes copper, and the preparation method of the first metal layer includes physical vapor deposition.

[0115] S230: Preparing a second metal layer on the surface of the first metal layer, wherein the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy, and the preparation method of the second metal layer includes physical vapor deposition or chemical deposition.

[0116] S240: preparing a third metal layer on the surface of the second metal layer, wherein the material of the third metal layer includes copper, and the preparation method of the third metal layer includes physical vapor deposition.

[0117] S250: performing a first acid wash on the third metal layer to remove oxide on the surface of the third metal layer.

[0118] S260: preparing a fourth metal layer on the surface of the third metal layer, wherein the material of the fourth metal layer includes copper, and the preparation method of the fourth metal layer includes electroplating.

[0119] S270: performing a second acid wash on the fourth metal layer to remove oxide on the surface of the fourth metal layer.

[0120] S280: preparing a mask layer on the surface of the fourth metal layer.

[0121] S290: using a first etching solution to perform a first etching on the fourth metal layer and the third metal layer exposed from the mask layer.

[0122] S300: using a second etching solution to perform a second etching on the second metal layer exposed from the mask layer.

[0123] S310: using a third etching solution to perform a third etching on the first metal layer exposed from the mask layer.

[0124] S320: removing the mask layer.

[0125] S330: preparing a fifth metal layer on the surface of the fourth metal layer, wherein the material of the fifth metal layer includes at least one of silver, silver alloy, tin and tin alloy.

[0126] S340: performing annealing treatment on the electrode.

[0127] Another embodiment of the present application provides an electrode, which is prepared by any of the above-mentioned electrode preparation methods, including: a first metal layer, a second metal layer, a third metal layer and a fourth metal layer stacked in sequence; the material of the first metal layer includes copper; the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy; the material of the third metal layer includes copper; the material of the fourth metal layer includes copper.

[0128] In some embodiments, the electrode includes a fifth metal layer located on a surface of the fourth metal layer, and a material of the fifth metal layer includes at least one of silver, a silver alloy, tin, and a tin alloy.

[0129] Another embodiment of the present application provides a solar cell, comprising: an electrode prepared by any of the above-mentioned methods for preparing an electrode, or any of the above-mentioned electrodes.

[0130] In some embodiments, a solar cell includes: a silicon substrate having a first surface and a second surface arranged opposite to each other, an n-type intrinsic amorphous silicon layer, an n-type doped layer, a first transparent conductive layer and a first electrode stacked in sequence on the first surface, and a p-type intrinsic amorphous silicon layer, a p-type doped layer, a second transparent conductive layer and a second electrode stacked in sequence on the second surface, the first electrode and the second electrode are each independently selected from electrodes prepared by the electrode preparation method of any of the above items or electrodes of any of the above items.

[0131] The following are specific embodiments

[0132] Example 1

[0133] Preparation of electrodes:

[0134] (1) The pre-cleaned solar cell pre-finished product is placed in the first chamber of magnetron sputtering, and a first metal layer is prepared on the surface of the transparent conductive layer by magnetron sputtering. The first metal layer is a seed copper layer, wherein the magnetron sputtering power is 150 W, the deposition rate is 0.5 nm / s, the deposition time is 20 s, and the thickness of the first metal layer is 10 nm.

[0135] (2) The solar cell sheet treated in step (1) is transferred to a second magnetron sputtering chamber, and a second metal layer is prepared on the surface of the first metal layer by magnetron sputtering. The second metal layer is a titanium layer, wherein the magnetron sputtering power is 150 W, the deposition rate is 0.5 nm / s, the deposition time is 20 s, and the deposition thickness is 10 nm.

[0136] (3) The solar cell sheet treated in step (2) is transferred to a third magnetron sputtering chamber, and a third metal layer is prepared on the surface of the second metal layer by magnetron sputtering. The third metal layer is a copper layer, wherein the magnetron sputtering power is 150 W, the deposition rate is 0.5 nm / s, the deposition time is 20 s, and the deposition thickness is 10 nm.

[0137] (4) After the solar cell sheet treated in step (3) is subjected to a first acid wash, it is placed in a copper plating bath for electroplating to prepare a fourth metal layer, wherein the fourth metal layer is a copper layer and has a thickness of 5 μm.

[0138] (5) After the solar cell sheet treated in step (4) is subjected to a second acid wash, a mask layer having an electrode pattern is formed on the surface of the fourth metal layer, wherein the mask layer is coated by inkjet printing.

[0139] (6) After curing, the solar cell sheet treated in step (5) is placed in an acidic etching solution to perform a first etching on the fourth metal layer and the third metal layer exposed from the mask layer at an etching temperature of 30° C. to 50° C. and an etching time of 60 s to 120 s.

[0140] (7) After washing the solar cell sheet treated in step (6), place it in a second etching solution to perform a second etching on the second metal layer exposed from the mask layer. The etching temperature is 30° C. to 50° C. and the etching time is 10 s to 60 s.

[0141] (8) After washing the solar cell sheet treated in step (7), place it in a third etching solution to perform a third etching on the first metal layer exposed from the mask layer at an etching temperature of 20° C. to 30° C. and an etching time of 10 s to 60 s.

[0142] (9) Place the solar cell sheet treated in step (8) into an alkaline cleaning solution to remove the mask layer. The alkaline cleaning temperature is 30°C to 50°C and the time is 20s to 60s.

[0143] (10) The solar cell sheet treated in step (9) is washed with water and then placed in a chemical tin plating solution to prepare a fifth metal layer. The fifth metal layer is a tin layer and has a thickness of 0.5 μm.

[0144] (11) After washing the solar cell sheet treated in step (10), place it in an oven for annealing at a temperature of 100°C to 150°C for a holding time of 0.5h to 3h.

[0145] Example 2

[0146] The preparation method of the electrode in Example 2 is basically the same as that in Example 1, the only difference is that in step (6), an alkaline etching solution is used to perform a first etching on the fourth metal layer and the third metal layer exposed from the mask layer.

[0147] Example 3

[0148] The preparation method of the electrode in Example 3 is basically the same as that in Example 1, the only difference is that the second metal layer in step (2) is a nickel layer.

[0149] Example 4

[0150] The preparation method of the electrode in Example 4 is basically the same as that in Example 1, except that the deposition time in step (1) is 200 s, and the thickness of the first metal layer is 100 nm, the deposition time in step (2) is 200 s, and the deposition thickness is 100 nm, the deposition time in step (3) is 200 s, and the deposition thickness is 100 nm, the thickness of the fourth metal layer in step (4) is 12 μm, and the thickness of the fifth metal layer in step (10) is 0.7 μm.

[0151] Example 5

[0152] The preparation method of the electrode in Example 5 is basically the same as that in Example 1, the difference is that the deposition time in step (1) is 400 s, the thickness of the first metal layer is 200 nm, the deposition time in step (2) is 400 s, the deposition thickness is 200 nm, the deposition time in step (3) is 400 s, the deposition thickness is 200 nm, the thickness of the fourth metal layer in step (4) is 20 μm, and the thickness of the fifth metal layer in step (10) is 1 μm.

[0153] Comparative Example 1

[0154] The only difference between Comparative Example 1 and Example 1 is that the second metal layer and the third metal layer are not prepared, and the fourth metal layer is directly prepared on the surface of the first metal layer.

[0155] Comparative Example 2

[0156] The only difference between Comparative Example 2 and Example 1 is that the third metal layer is not prepared, and the fourth metal layer is directly prepared on the surface of the second metal layer.

[0157] Comparative Example 3

[0158] The electrode in Comparative Example 3 adopts the traditional copper electrode preparation method: preparing the first metal layer (copper seed crystal layer) on the surface of the battery cell - mask layer - electroplating the fourth metal layer (copper thickening layer) - preparing the fifth metal layer (tin layer) - removing the mask layer - etching the first metal layer.

[0159] Comparative Example 4

[0160] In Comparative Example 4, the electrode is prepared by screen printing low-temperature silver paste to prepare the silver electrode, and the thickness of the silver electrode is 10 μm to 20 μm.

[0161] The solar cells after the electrode preparation in Examples 1 to 5 and Comparative Examples 1 to 4 were tested for photoelectric conversion efficiency and bonding strength. The bonding strength test adopted the tensile test method (GB / T 29195-2012). The test results are shown in Table 1 below:

[0162] Table 1

[0163]

[0164] In Examples 1 to 5, the electrode preparation method of the present scheme is used to prepare the electrode. In the case of using a copper electrode, the first metal layer is protected by the second metal layer, and the second metal layer is protected by the third metal layer, so that a good bonding effect between the layers can be achieved, and a higher photoelectric conversion efficiency of the solar cell can be achieved, and the photoelectric conversion efficiency and bonding force equivalent to those of the silver electrode solar cell can be achieved. By comparing the test results of Comparative Example 3 and Example 1, it can be seen that in the traditional method for preparing a copper electrode, the bonding force between the thickened copper layer and the copper seed layer is weak, which may be caused by the oxidation of the surface of the copper seed layer, and the seed layer is easily damaged during the etching process, resulting in a lower photoelectric conversion efficiency. By comparing Comparative Example 2 and Example 1, it can be seen that without the preparation of the third metal layer, the separation occurs between the second metal layer and the fourth metal layer. This is because after losing the protection of the third metal layer, the second metal layer is easily oxidized, resulting in a poor effect of electroplating copper directly on the surface of the second metal layer, which in turn leads to a lower photoelectric conversion efficiency of the solar cell. By comparing Comparative Example 1 and Example 1, it can be seen that the second metal layer is not prepared to protect the first metal layer, which results in the first metal layer being easily damaged during the etching process, thereby resulting in a lower photoelectric conversion efficiency of the solar cell.

[0165] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0166] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A method for preparing an electrode, characterized in that: include: providing a substrate; Preparing a first metal layer on the surface of the substrate, wherein the material of the first metal layer includes copper, and the preparation method of the first metal layer includes physical vapor deposition; Preparing a second metal layer on the surface of the first metal layer, wherein the material of the second metal layer comprises at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy; Preparing a third metal layer on the surface of the second metal layer, wherein the material of the third metal layer includes copper, and the preparation method of the third metal layer includes physical vapor deposition; Preparing a fourth metal layer on the surface of the third metal layer, wherein the material of the fourth metal layer includes copper, and the preparation method of the fourth metal layer includes electroplating; Preparing a mask layer on the surface of the fourth metal layer; Performing a first etching on the fourth metal layer and the third metal layer exposed from the mask layer using a first etching solution; Performing a second etching on the second metal layer exposed from the mask layer using a second etching solution; Performing a third etching on the first metal layer exposed from the mask layer using a third etching solution; The mask layer is removed.

2. The method for preparing an electrode according to claim 1, characterized in that: The thickness of the first metal layer is 10nm to 200nm; And / or, the thickness of the second metal layer is 10nm to 200nm; And / or, the thickness of the third metal layer is 10nm to 200nm; And / or, the thickness of the fourth metal layer is 5 μm to 20 μm.

3. The method for preparing an electrode according to any one of claims 1 to 2, characterized in that: Before preparing the fourth metal layer on the surface of the third metal layer, the method further includes: The third metal layer is first pickled to remove oxide on the surface of the third metal layer.

4. The method for preparing an electrode according to claim 1, characterized in that: The first etching solution includes an acidic etching solution or an alkaline etching solution, the acidic etching solution includes 120 g / L to 180 g / L of copper chloride and 30 g / L to 70 g / L of hydrochloric acid, and the alkaline etching solution includes copper chloride and ammonia water with a mass volume concentration of 120 g / L to 180 g / L, respectively; And / or, the second etching solution comprises 5% to 15% by mass of hydrogen peroxide and 1% to 5% by mass of phosphoric acid, and the pH value of the second etching solution is 1 to 3; And / or, the third etching solution comprises 0.1% to 0.5% by mass of sulfuric acid and 1% to 3% by mass of sodium persulfate, and the pH range of the third etching solution is 1 to 3.

5. The method for preparing an electrode according to claim 1, characterized in that: The temperature of the first etching is 30° C. to 50° C.; And / or, the first etching time is 60s to 120s; And / or, the temperature of the second etching is 30° C. to 50° C.; And / or, the second etching time is 10s to 60s; And / or, the temperature of the third etching is 20° C. to 30° C.; And / or, the third etching time is 10s to 60s.

6. The method for preparing an electrode according to claim 1, characterized in that: Before preparing a mask layer on the surface of the fourth metal layer, the method further includes: The fourth metal layer is subjected to a second acid wash to remove oxide on the surface of the fourth metal layer.

7. The method for preparing an electrode according to claim 1, characterized in that: After removing the mask layer, the method further comprises: A fifth metal layer is prepared on the surface of the fourth metal layer, and a material of the fifth metal layer includes at least one of silver, silver alloy, tin and tin alloy.

8. The method for preparing an electrode according to claim 7, characterized in that: After forming the fifth metal layer on the surface of the fourth metal layer, the method further includes: annealing the electrode; The temperature of the annealing treatment is 100° C. to 150° C., and / or the holding time of the annealing treatment is 0.5 h to 3 h.

9. An electrode, characterized in that: The electrode is prepared by the method for preparing the electrode according to any one of claims 1 to 8, comprising: A first metal layer, a second metal layer, a third metal layer and a fourth metal layer are stacked in sequence; The material of the first metal layer includes copper; the material of the second metal layer includes at least one of titanium, titanium alloy, nickel, nickel alloy, chromium, chromium alloy, silver, silver alloy, molybdenum, molybdenum alloy, manganese and manganese alloy; the material of the third metal layer includes copper; the material of the fourth metal layer includes copper.

10. A solar cell, characterized in that: include: An electrode prepared by the method for preparing an electrode according to any one of claims 1 to 8, or an electrode according to claim 9.

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