Conductive contact structure for solar cell, solar cell module and power generation system

Abstract

The present invention provides a conductive contact structure for a solar cell, comprising: a substrate; a semiconductor region; and an electrode, the semiconductor region being disposed on or within the substrate; the electrode being disposed within the semiconductor region; the electrode comprising a seed layer in contact with the semiconductor region; the seed layer comprising an alloy material, the seed layer comprising a main component and a reinforcing component, the main component being one or more metals having an average refractive index of less than 2 and a wavelength range of 850-1200 nm, and the reinforcing component being any one or more of Mo, Ni, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V.

Description

[Technical Field]

[0001] The present invention relates to the technical field of solar cells, and in particular to a conductive contact structure for a solar cell, a solar cell module and a power generation system. [Background technology]

[0002] As shown in Figure 2, solar cells typically use a copper layer 100 as a conductive layer covering a silicon substrate 200. However, due to insufficient bonding between copper and silicon, the conductive layer is prone to peeling off from the silicon substrate. Furthermore, copper in the conductive layer diffuses into the silicon substrate, resulting in reduced solar cell performance. To address this issue, prior art techniques add a seed layer 300 between the copper conductive layer and the silicon substrate to strengthen the bonding between the copper conductive layer 100 and the silicon substrate 200. The seed layer typically uses a nickel layer, which strengthens the bonding between the copper conductive layer and the silicon substrate, but the strengthening effect is not ideal and the nickel layer has poor light reflection properties, reducing the light trapping effect of the solar cell. Summary of the Invention

[0003] The present invention aims to strengthen the bonding strength between the conductive layer and the substrate and improve the light trapping effect of the solar cell, and provides a conductive contact structure for the solar cell, a solar cell module and a power generation system.

[0004] To achieve this goal, the present invention adopts the following technical solutions:

[0005] A conductive contact structure for a solar cell is provided, the conductive contact structure for the solar cell comprising: A substrate; a semiconductor region; an electrode; the semiconductor region is disposed on or within the substrate; the electrode is disposed within the semiconductor region; the electrode includes a seed layer in contact with the semiconductor region; The seed layer includes an alloy material, and includes a main component and a reinforcing component, the main component being one or more metals with an average refractive index of less than 2 and a wavelength range of 850 to 1200 nm, and the reinforcing component being one or more of Mo, Ni, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V.

[0006] In one class of this embodiment, the primary element comprises any one or more of Al, Ag, Cu, and Mg.

[0007] In one class of this embodiment, the reinforcing component may further comprise a non-metallic component.

[0008] In one class of this embodiment, the major component is present in an amount greater than 50 wt.% of the seed layer.

[0009] In one class of this embodiment, the primary component is Al in an amount equal to or greater than 70 wt.% of the seed layer, and the reinforcing component is Ni in an amount equal to or less than 30 wt.% of the seed layer.

[0010] In one class of this embodiment, the primary component is Al in an amount greater than or equal to 70 wt.% of the seed layer, and the reinforcing component is W in an amount less than or equal to 30 wt.% of the seed layer.

[0011] In one class of this embodiment, the primary component is Al in an amount equal to or greater than 70 wt.% of the seed layer, and the reinforcing component is Ti in an amount equal to or less than 30 wt.% of the seed layer.

[0012] In one class of this embodiment, the primary component is Al in an amount equal to or greater than 70 wt.% of the seed layer, and the reinforcing component is Mo in an amount equal to or less than 30 wt.% of the seed layer.

[0013] In a class of this embodiment, the primary component is Al and comprises at least 70 wt.% of the seed layer, and the reinforcing component is Cr and comprises at most 30 wt.% of the seed layer. In a class of this embodiment, the primary component is Al and comprises at least 70 wt.% of the seed layer, and the reinforcing component is Si and comprises at most 30 wt.% of the seed layer.

[0014] In one class of this embodiment, the seed layer is formed on the substrate by any one of the following manufacturing methods: physical vapor deposition, screen printing, chemical vapor deposition, electroplating, or electroless plating.

[0015] In one class of this embodiment, the electrode further includes a conductive layer disposed above the seed layer.

[0016] In one class of this embodiment, the conductive layer comprises any one or more of Cu, Ag, and Al.

[0017] In one class of this embodiment, a passivation film is formed between the seed layer and the semiconductor region, an opening is provided in the passivation film, and the seed layer contacts the semiconductor region through the opening.

[0018] In one class of this embodiment, a transparent conductive oxide (TCO) thin film is further provided between the seed layer and the passivation film, the TCO thin film contacting the semiconductor region through the opening in the passivation film.

[0019] In one class of this embodiment, the TCO thin film is a tin-doped indium oxide or zinc oxide based thin film.

[0020] In one class of this embodiment, the semiconductor region includes a tunnel oxide layer and doped polysilicon.

[0021] In one class of this embodiment, the method for growing the conductive layer on the seed layer comprises electroplating, physical vapor deposition, screen printing, or chemical plating.

[0022] In one class of this embodiment, a protective layer is coated on top of the conductive layer.

[0023] In one class of this embodiment, the protective layer is a Sn layer or an Ag layer.

[0024] In one class of this embodiment, the protective layer is grown on the conductive layer by electroplating or chemical plating methods.

[0025] In one class of this embodiment, the substrate is a silicon substrate.

[0026] In one class of this embodiment, the seed layer is comprised of a plurality of sub-seed layers stacked one on top of the other.

[0027] In one class of this embodiment, the content of the major component in the subseed layers deposited in a direction away from the substrate gradually decreases.

[0028] In one class of this embodiment, the seed layer has a thickness in the range of 10 nm to 1000 nm.

[0029] In one class of this embodiment, the seed layer has a thickness in the range of 30 nm to 300 nm.

[0030] In one class of this embodiment, the conductive layer has a thickness in the range of 1 μm to 800 μm.

[0031] In one class of this embodiment, the conductive layer has a thickness in the range of 1 μm to 100 μm.

[0032] The present invention further provides a solar cell including the conductive contact structure described above.

[0033] The present invention further provides a solar cell module including a plurality of solar cells electrically connected to one another.

[0034] The present invention further provides a photovoltaic power generation system including a plurality of solar cell modules electrically connected to one another.

[0035] The present invention adds a seed layer between the conductive layer and the substrate, and the seed layer contains an alloy material whose main component is one or more metals with an average refractive index of less than 2 and a wavelength range of 850 to 1200 nm, and whose reinforcing component is one or more of Mo, Ni, Ti, W, Cr, Si, Mn, Pd, Bi, Nb, Ta, Pa, or V. The seed layer formed by the fusion of the main component and the reinforcing component has a strong bond to both the conductive layer and the substrate, and improves the light trapping effect of the solar cell. [Brief explanation of the drawings]

[0036] In the following, in order to more clearly describe the technical solutions of the embodiments of the present invention, a brief description will be given of the drawings used in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings from these drawings without any creative efforts.

[0037] [Figure 1] 1 is a schematic diagram of a conductive contact structure of a solar cell according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of a conductive contact structure of a solar cell in the prior art; [Figure 3] FIG. 1 is a comparison diagram of the diffusion coefficients of Cu and other metals. DETAILED DESCRIPTION OF THE INVENTION

[0038] The technical solutions of the present invention are further described below through specific embodiments with reference to the drawings.

[0039] Here, the drawings are merely for illustrative purposes, and are not actual drawings but merely schematic diagrams, and should not be understood as limiting the present invention. In order to better explain the embodiments of the present invention, some components may be omitted, enlarged, or reduced in size in the drawings, and the drawings do not represent the dimensions of actual products. Those skilled in the art will understand that some known structures and their descriptions may be omitted in the drawings.

[0040] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In describing the present invention, it should be understood that the orientations or positional relationships indicated by the terms "upper," "lower," "left," "right," "inner," "outer," etc. are orientations or positional relationships indicated based on the drawings, and are merely intended to facilitate explanation and simplify the description of the present invention. It does not explicitly or implicitly imply that the devices or elements described necessarily have a specific orientation, or are configured or operated in a specific orientation. Therefore, the terms used to describe the positional relationships in the drawings are merely for illustrative purposes and should not be construed as limiting the present invention. Those skilled in the art can understand the specific meanings of the terms according to specific circumstances.

[0041] In the description of the present invention, unless otherwise clearly defined or limited, when a term indicating a connection relationship between elements, such as "connect," appears, the term should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or integration, a mechanical connection, an electrical connection, a direct connection, or even an indirect connection via an intermediate medium, or an internal communication between two elements or an interactive relationship between two elements. Those skilled in the art will be able to understand the specific meaning of the above terms in the present invention according to specific circumstances.

[0042] The conductive contact structure of the solar cell provided in the embodiment of the present invention is as shown in FIG. A substrate 1; a semiconductor region disposed on or within a substrate 1; an electrode 100 disposed within the semiconductor region; The electrode includes a seed layer 2 in contact with the semiconductor region; The seed layer 2 includes an alloy material, and includes a main component and a reinforcing component, the main component being one or more metals (preferably one or more of Al (aluminum), Ag (silver), Cu (copper), or Mg (magnesium)) having an average refractive index of less than 2 and a wavelength range of 850 to 1200 nm, and the reinforcing component being one or more of Mo (molybdenum), Ti (titanium), W (tungsten), Ni (nickel), Cr, Si, Mn, Pd, Bi, Nb, Ta, Pa, or V. The content of the main component in the seed layer is preferably >50%. More preferably, the main component of the seed layer is Al, the content of which is 70 wt.% or more of the seed layer, and the reinforcing component is Ti, the content of which is 30 wt.% or less of the seed layer; alternatively, the main component is Al, the content of which is 70 wt.% or more of the seed layer, and the reinforcing component is W, the content of which is 30 wt.% or less of the seed layer; alternatively, the main component is Al, the content of which is 70 wt.% or more of the seed layer, and the reinforcing component is Ti, the content of which is 30 wt.% or less of the seed layer; alternatively, the main component is Al, the content of which is 70 wt.% or more of the seed layer, and the reinforcing component is Mo, the content of which is 30 wt.% or less of the seed layer.

[0043] Currently, mass-produced crystalline silicon solar cells use Ag paste as the electrode material, and the cost of Ag paste accounts for nearly 30% of the non-silicon cost of the cell. Reducing the amount of Ag used or eliminating Ag production technology can effectively reduce the production cost of solar cells. Cu is a good substitute for Ag, and the advantages of using Cu as a conductive material compared to Ag are shown in Table 1 below.

[0044] [Table 1]

[0045] Table 1 above shows that Cu is an effective substitute for Ag due to its excellent properties, including relatively stable chemical properties, excellent ductility, sufficiently low volume resistivity, and being available in large quantities and inexpensive (nearly 1 / 72 the price of Ag material). However, Cu has two important characteristics that limit its application in solar cells. One of these is its extremely large diffusion coefficient. Figure 3 is a schematic diagram of the diffusion coefficients of common metals. The abscissa and ordinate in Figure 3 represent the inverse of temperature (units: Kelvin K) and the diffusion coefficient of the metal element, respectively. Figure 3 clearly shows that the diffusion coefficient of Cu is much higher than that of other metals, by five orders of magnitude higher than Ag / Al, etc.

[0046] Secondly, Cu defects have a large collection cross section for holes, which significantly shortens the bulk lifetime and further reduces the electrical performance of the solar cell. The effects of Cu content on bulk lifetime and electrical performance are shown in Table 2 below.

[0047] [Table 2]

[0048] From Table 2 above, it can be seen that as the Cu content increases, the bulk lifetime is significantly shortened and the cell efficiency is also significantly reduced. 3 Even if only 1000mAh is used, the battery efficiency drops by 0.29%.

[0049] In conventional technology, nickel (Ni) is typically used as a barrier layer against Cu diffusion and has good adhesion to the substrate and Cu electrode. The general process for achieving this is to prepare a coated substrate, laser cut out a mold, electroplate Ni, and electroplate a Cu layer. However, the inventors discovered during their research that Ni has a major drawback as a barrier layer for Cu: it has poor reflection properties in the long wavelength range, which reduces the light trapping effect of the cell and further reduces the cell's conversion efficiency.

[0050] See Table 3 below for comparative data on the optical performance of batteries using Ni+Cu and Ag as electrode materials.

[0051] [Table 3]

[0052] From Table 3 above, we can see that the combination of Ni and Cu significantly reduces the short circuit current density of the battery. Simulation results show that the short circuit current density is 0.75mA / cm 2 However, experimental results show that the short-circuit current density is 1.36 mA / cm 2 The decrease is greater than theoretically predicted.

[0053] The light trapping effect of common metals will be analyzed below.

[0054] Currently, the thickness of silicon wafers in finished batteries is approximately 150 μm, and photons with wavelengths >850 nm can effectively penetrate this thickness. At the same time, because the forbidden band width of Si is 1.12 eV, photons with wavelengths >1200 nm are unlikely to excite electron-hole pairs. Therefore, when considering the light trapping effect, the inventors focus primarily on the wavelength range of 850-1200 nm. Table 4 below shows the interface reflectance of different metals and market prices as of February 2022.

[0055] [Table 4]

[0056] Table 4 above clearly shows that there is a large difference in interface reflectivity between different metals. Among these, Ag, Al, Cu, and Mg are able to achieve relatively ideal short-circuit current density results, and all four metals can achieve effective light trapping when used as seed layers. Further analysis reveals that Cu cannot be used as a seed layer because one of the key roles of the seed layer is to block Cu. Mg is also not a desirable option due to its excessive chemical activity, and Ag is also not a desirable option due to its high price. On the other hand, Al is an ideal seed layer metal because it has excellent backside reflectivity, relatively stable chemical properties, and is inexpensive, costing only 1 / 223 of Ag and 1 / 3 of Cu.

[0057] However, using pure aluminum as a seed layer presents another problem: the adhesion between aluminum and other metals is weak. The technology of using pure aluminum as a seed layer results in products that do not meet reliability standards. When the product is subjected to thermal cycling or bending, or when stress is applied to the welding points during welding of parts, separation of the aluminum from the outer metal layer can occur, leading to delamination and failure.

[0058] The bonding strength between Al and Cu is weak, which easily leads to large-area finger detachment. To solve this problem, the inventors tried various methods, such as increasing the contact area between Al and substrate, increasing the sample temperature to promote interdiffusion between the metals, and sandwiching new materials such as TiW between the Al and Cu materials. However, none of these methods were effective. Finally, they discovered that adding a reinforcing component that can form a good interconnection with Cu to the Al material as a seed layer significantly improved the adhesion of the electroplated layer, even without the need for an additional annealing treatment after Cu electroplating. This ultimately solved the problem.

[0059] Reinforcing elements such as Ni, Mo, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V significantly enhance adhesion.

[0060] Furthermore, Ni, Mo, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, and Si have low reflectivity. Adding too much of a material can degrade optical performance. Taking W as an example, we simply assume that the performance of the alloying elements is the average strengthening value of the elements, and obtain the estimated results shown in Table 5 below.

[0061] [Table 5]

[0062] Here, when the W content is 30%, the current loss is 0.36 mA / cm 2 This results in a decrease in the cell conversion efficiency of about 0.2%, which is relatively large, but considering the cost reduction achieved by substituting Cu for Ag and the solution to the reliability issue, it is worth accepting. Therefore, a reinforcing component of 30 wt.% or less in the seed layer is considered to be the recommended value.

[0063] Furthermore, the proportion of the reinforcing component in the seed layer of the present invention may be distributed unevenly, and in this way, more favorable performance effects can be obtained. The principle is that by reducing the content of the reinforcing component in the part close to the substrate, the light reflection can be strengthened, and by containing a relatively large amount of the reinforcing component in the part in contact with the conductive layer metal, the bonding strength with the conductive layer metal can be improved.

[0064] Table 6 below compares the weld pull forces for different electrode technologies.

[0065] [Table 6]

[0066] From Table 6 above, it can be seen that the pure Al seed layer has a relatively low finger tensile strength, which is much lower than that of a normal Ag electrode; however, after directly sandwiching the TiW material between Al and Cu, the welding tensile strength is improved but still insufficient, whereas the solar cell manufactured with the Al alloy seed layer of the present invention has a higher welding tensile strength than that of a normal Ag electrode.

[0067] Al is used as the main component to improve the adhesion between the seed layer and the Cu conductive layer and the light trapping effect of the solar cell. Table 7 shows the technical effect data that can be brought about by combining each single reinforcing component with the main component Al.

[0068] [Table 7]

[0069] As can be seen from the above experimental data, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V can also be used as reinforcing components to improve the adhesion between the seed layer and the Cu conductive layer and the light trapping effect of the solar cell. It should be emphasized that any one or more of the reinforcing components Mo, Ni, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V can be combined with Al in hundreds of combinations, and it is impossible to provide experimental comparison data for all components in this invention. Therefore, given the experimental data for Ni, Mo, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V as individual reinforcing components in a specific implementation, it is clear that other reinforcing components combined with the main component Al can also achieve the desired technical effect.

[0070] Furthermore, it is preferable that the thickness of the seed layer is ≧30 nm. Experiments have shown that a seed layer with a thickness of 30 nm is sufficient to prevent the diffusion of Cu metal. When the thickness is ≦300 nm, the main factor to consider is cost control. For example, even if the seed layer is manufactured using physical vapor deposition and the price of Al is lower than other metals, the impact of the cost of the Al target material is still not negligible. In addition, the thicker the seed layer, the lower the production capacity of the equipment, which is disadvantageous for the widespread use of large-scale production. Therefore, it is preferable that the thickness of the seed layer is 30 nm to 300 nm.

[0071] Furthermore, to save the cost of alloy target material and further limit the diffusion of Cu metal into the substrate, a transparent conductive oxide (TCO) layer can be added between the alloy seed layer and the substrate, allowing long-wavelength light to penetrate the TCO layer and be effectively reflected at the alloy layer interface, similarly achieving ideal performance and reliability results.

[0072] In the above solution, the seed layer is preferably formed on the substrate by any one of physical vapor deposition (including sputtering and evaporation), screen printing, chemical vapor deposition, electroplating, and chemical plating. The seed layer is preferably formed by stacking multiple subseed layers, and more preferably, the content of the main component in the subseed layers stacked in the direction away from the substrate gradually decreases. A high content of the main component in the subseed layer closer to the substrate can enhance the light reflection effect and improve the light trapping effect of the solar cell. Furthermore, a high content of the reinforcing component and a relatively low content of the main component in the subseed layer farther from the substrate (closer to the conductive layer) can ensure the bonding strength between the subseed layer and the conductive layer.

[0073] The thickness of the seed layer is preferably 10 nm to 1000 nm, and more preferably in the range of 30 nm to 300 nm.

[0074] As shown in FIG. 1, the electrode provided in this embodiment further includes a conductive layer 3 disposed above the seed layer 2. The material for manufacturing the conductive layer 3 includes one or more of Cu, Ag, and Al. Methods for growing the conductive layer on the seed layer include electroplating, physical vapor deposition, screen printing, or chemical plating. The thickness of the conductive layer is preferably in the range of 1 to 800 μm, and more preferably in the range of 1 to 100 μm.

[0075] To protect the conductive layer, the upper part of the conductive layer is preferably covered with a protective layer 4. More preferably, the protective layer 4 is a Sn layer or an Ag layer. The protective layer 4 is preferably grown on the conductive layer 3 by electroplating or chemical plating.

[0076] 1 , a passivation film 6 for protecting the seed layer 2 is preferably formed between the seed layer 2 and the semiconductor region, and an opening 7 is provided in the passivation film 6, through which the seed layer 2 contacts the semiconductor region. More preferably, a TCO thin film is further disposed between the seed layer 2 and the passivation film 6, and the TCO thin film contacts the semiconductor region through the opening in the passivation film. The semiconductor region preferably includes a tunnel oxide layer 5 and doped polysilicon 8.

[0077] As described above, the present invention adds a seed layer between the conductive layer and the substrate, and the seed layer contains an alloy material whose main component is one or more metals with an average refractive index of less than 2 and a wavelength range of 850 to 1200 nm, and whose reinforcing component is one or more of Mo, Ni, Ti, W, Cr, Si, Mn, Pd, Bi, Nb, Ta, Pa, or V. The seed layer formed by the fusion of the main component and the reinforcing component has a strong bond with both the conductive layer and the substrate, and improves the light trapping effect of the solar cell.

[0078] Embodiments of the present invention further provide a solar cell including the conductive contact structure described above.

[0079] An embodiment of the present invention further provides a solar cell module including a plurality of solar cells electrically connected to one another and having the above-described conductive contact structures.

[0080] An embodiment of the present invention further provides a solar power generation system including a plurality of solar cell modules electrically connected to one another.

[0081] It should be noted that the above-described specific embodiments are merely preferred examples and applied technical principles of the present invention. It is obvious to those skilled in the art that various modifications, equivalent substitutions, changes, etc. can be made to the present invention. However, as long as these transformations do not deviate from the spirit of the present invention, they are all intended to be included in the protection scope of the present invention. Furthermore, some terms used in the specification and claims of this application are merely for the purpose of facilitating explanation and are not limiting.

Claims

1. A substrate; a semiconductor region; An electrode; 1. A conductive contact structure for a solar cell, comprising: the semiconductor region is disposed on or within the substrate; the electrode is disposed on the semiconductor region; the electrode includes a seed layer in contact with the semiconductor region and a conductive layer disposed above the seed layer; the seed layer comprises an alloy material and includes a main component and a reinforcing component; The main component is Al, and the content of the Al is 70 wt. % or more of the seed layer; The reinforcing component includes any one of Mo, Ni, Ti, W, and Cr, and the content thereof is 30 wt. % or less of the seed layer; The conductive layer is made of Cu. Conductive contact structures for solar cells.

2. 2. The conductive contact structure of claim 1, wherein the seed layer is formed on the substrate by using a physical vapor deposition manufacturing method, or a screen printing manufacturing method, or a chemical vapor deposition manufacturing method, or an electroplating manufacturing method, or a chemical plating manufacturing method.

3. A substrate; a semiconductor region; An electrode; 1. A conductive contact structure for a solar cell, comprising: the semiconductor region is disposed on or within the substrate; the electrode is disposed on the semiconductor region; the electrode includes a seed layer in contact with the semiconductor region; the seed layer comprises an alloy material, and includes a main component and a reinforcing component, the main component being one or more metals having an average refractive index of less than 2 and a wavelength range of 850 to 1200 nm, and the reinforcing component being any one or more of Mo, Ni, Ti, W, Cr, Mn, Pd, Bi, Nb, Ta, Pa, Si, and V; a passivation film is formed between the seed layer and the semiconductor region, an opening is provided in the passivation film, and the seed layer contacts the semiconductor region through the opening; a transparent conductive oxide (TCO) thin film is further disposed between the seed layer and the passivation film, the TCO thin film contacting the semiconductor region through the opening in the passivation film; Conductive contact structures for solar cells.

4. The conductive contact structure for a solar cell according to claim 3 , wherein the TCO thin film is a tin-doped indium oxide or zinc oxide based thin film.

5. 10. The conductive contact structure for a solar cell of claim 1, wherein the semiconductor region comprises a tunnel oxide layer and doped polysilicon.

6. 10. The conductive contact structure for a solar cell of claim 1, wherein the method for growing the conductive layer on the seed layer comprises electroplating, physical vapor deposition, screen printing, or chemical plating.

7. The conductive contact structure for a solar cell according to claim 1 , wherein the conductive layer is covered with a protective layer.

8. The conductive contact structure for a solar cell according to claim 7 , wherein the protective layer is a Sn layer or an Ag layer.

9. The conductive contact structure for a solar cell according to claim 7 , wherein the protective layer is grown on the conductive layer by electroplating or chemical plating method.

10. The conductive contact structure for a solar cell according to claim 1 , wherein the substrate is a silicon substrate.

11. The conductive contact structure for a solar cell according to claim 1 , wherein the seed layer is formed by stacking a plurality of sub-seed layers.

12. 12. The conductive contact structure for a solar cell of claim 11, wherein the content of the main component in the subseed layer decreases along a direction away from the substrate.

13. 12. The conductive contact structure for a solar cell of claim 11, wherein the seed layer has a thickness in the range of 10 nm to 1000 nm.

14. 12. The conductive contact structure for a solar cell of claim 11, wherein the thickness of the seed layer is in the range of 30 nm to 300 nm.

15. The conductive contact structure for a solar cell according to claim 1, wherein the thickness of the conductive layer is in the range of 1 μm to 800 μm.

16. The conductive contact structure for a solar cell according to claim 1, wherein the thickness of the conductive layer is in the range of 1 μm to 100 μm.

17. A solar cell comprising the conductive contact structure of any one of claims 1 to 16.

18. A solar cell module comprising a plurality of solar cells comprising the conductive contact structure of any one of claims 1 to 16 electrically connected to each other.

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