Application of silver nanowire in preparation of cadmium telluride solar cell back contact layer

Abstract

The invention discloses an application of a silver nanowire in preparation of a cadmium telluride solar cell back contact layer. According to the scheme provided by the invention, the silver nanowire has a relatively high work function, so that the silver nanowire and the p-type CdTe absorption layer form low-resistance and stable ohmic contact, and the interface potential barrier of carrier transmission is effectively reduced. Compared with the traditional back contact material, the high-cost magnetron sputtering equipment does not need to be adopted, so that the cost is obviously reduced; and meanwhile, excessive diffusion of copper atoms in the CdTe layer is avoided due to the characteristic of the one-dimensional nano structure, so that the problems of cell performance degradation, low conversion efficiency of the solar cell, poor stability and the like caused by out-of-control copper doping are avoided. The back contact layer material prepared by using the silver nanowires significantly improves the photoelectric conversion efficiency and long-term stability of the CdTe solar cell.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic solar cell technology, specifically to the application of silver nanowires in the preparation of the back contact layer of cadmium telluride solar cells. Background Technology

[0002] Cadmium telluride (CdTe), a typical direct bandgap compound semiconductor material, has a bandgap of 1.45 eV that closely matches the theoretical optimum for solar photovoltaic conversion (approximately 1.34-1.42 eV). This band structure characteristic allows a CdTe thin film absorber layer with a thickness of only about 2 μm to achieve a photon capture efficiency exceeding 90% in the visible to near-infrared band, laying the physical foundation for efficient photogenerated carrier generation. Thin-film solar cells constructed based on this material system can achieve a theoretical power conversion efficiency limit of 27% under standard solar spectrum (AM1.5) irradiation conditions. Furthermore, CdTe thin film deposition processes also show good engineering potential: through advanced techniques such as vapor transport deposition (VTD), large-area (>1.2 μm) deposition can be achieved. 2 The rapid and uniform film formation on the substrate, with a single-line production capacity exceeding 300MW / year, and the ability to reduce the manufacturing cost of battery modules to below $0.20 / W under large-scale production conditions, make CdTe thin-film photovoltaic technology one of the most commercially promising photovoltaic solutions, especially in the fields of building-integrated photovoltaics (BIPV) and large-scale ground-mounted power plants.

[0003] Traditional cadmium telluride thin-film solar cells employ a stacked structure (such as...) Figure 1 As shown in the diagram, from bottom to top, the layers are: a transparent substrate layer 1101, a transparent conductive oxide (TCO) front electrode layer 1201, a cadmium sulfide (CdS) window layer 1301, a cadmium telluride (CdTe) absorber layer 1401, and a metal back electrode layer 1501. Recent structural innovations have focused on the optimized design of window layer materials. By introducing cadmium selenide (CdSe) to replace the traditional CdS window layer and precisely controlling the deposition process parameters of the CdSe thin film, successful structures such as... Figure 2 The novel device architecture shown (from bottom to top: transparent substrate 1101, transparent conductive oxide (TCO) front electrode layer 1201, CdTe) 1-x Se x Window layer 1302, cadmium telluride (CdTe) absorber layer 1401, and metal back electrode layer 1501. The key to this structure is the formation of CdTe. 1-x Se x The CdTe gradient bandgap heterojunction absorber essentially replaces the traditional CdS window layer. This gradient bandgap design breaks through the limitations of traditional single-component absorbers and has shown positive effects in defect passivation, extending minority carrier lifetime, and improving carrier transport.

[0004] However, regardless of whether it's a traditional or novel structure, the back contact interface of the CdTe absorber layer presents a key challenge: CdTe semiconductor material has a high work function (approximately 5.7 eV), significantly higher than that of commonly used back electrode metals. If the metal is directly contacted with the CdTe layer, a high-barrier Schottky contact will form at the interface due to the significant work function difference. This barrier severely hinders the transport of photogenerated holes to the back electrode, leading to a degraded battery performance.

[0005] Currently, the mainstream solution is to insert a copper-doped semiconductor material with a high work function as a back contact layer between the CdTe absorber layer and the back electrode. This intermediate layer can effectively reduce the band mismatch at the CdTe / metal interface and lower the contact barrier's obstruction of hole transport, thereby significantly improving hole extraction efficiency. Specifically, magnetron sputtering is currently the main method used to prepare copper-doped zinc telluride, mercury telluride, or antimony telluride semiconductor materials. These materials are mostly compound semiconductors, which are relatively expensive and require vacuum magnetron sputtering equipment, resulting in a large investment and thus a high cost for cadmium telluride thin-film solar cells. In addition, because copper diffuses rapidly in cadmium telluride, when copper accumulates at the cadmium telluride-sulfide interface, it forms a large number of defect energy levels, which can easily cause cell degradation and thus affect the stability of the cell.

[0006] Therefore, developing new back contact layer materials is of great significance for reducing costs and improving reliability. Summary of the Invention

[0007] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes the application of silver nanowires in the preparation of the back contact layer of cadmium telluride solar cells.

[0008] The present invention also proposes a back contact layer material for cadmium telluride solar cells.

[0009] This invention also proposes a method for preparing a back contact layer material for cadmium telluride solar cells.

[0010] The present invention also proposes a cadmium telluride solar cell.

[0011] According to one aspect of the present invention, the application of silver nanowires in the preparation of the back contact layer of cadmium telluride solar cells is proposed.

[0012] According to the embodiments of the present invention, at least the following beneficial effects are achieved: The present invention proposes a cadmium telluride (CdTe) solar cell technology based on silver nanowires as the back contact layer. The core advantage of this solution lies in the high work function of silver nanowires, which allows them to form a low-resistance, stable ohmic contact with the p-type CdTe absorber layer, effectively reducing the interfacial barrier for carrier transport. Compared with traditional back contact materials, it eliminates the need for expensive magnetron sputtering equipment, significantly reducing costs. Simultaneously, the one-dimensional nanostructure avoids excessive diffusion of copper atoms within the CdTe layer, thereby preventing problems such as battery performance degradation, low solar cell conversion efficiency, and poor stability caused by uncontrolled copper doping. The back contact layer material prepared using silver nanowires significantly improves the photoelectric conversion efficiency and long-term stability of CdTe solar cells.

[0013] According to some embodiments of the present invention, the silver nanowires have a diameter of 25–100 nm and a length of 10 μm or more. The silver nanowires used in this invention refer to one-dimensional silver metal materials with lengths in the micrometer scale and diameters in the nanometer scale. They can be prepared by chemical growth. Using silver nanowires to form conductive films as back contact materials not only provides excellent photoelectric properties but also features a simple preparation process, easily achieving large-area film formation; furthermore, it requires no complex operations or expensive equipment, thus possessing promising prospects for industrial applications.

[0014] According to some embodiments of the present invention, the preparation method of the silver nanowires includes at least one of the following: polyol method, hydrothermal method, microwave-assisted method, ultraviolet reduction method, hard template method, or electrochemical deposition method. Conventional preparation methods can be used.

[0015] According to some embodiments of the present invention, the raw materials for preparing the back contact layer of the cadmium telluride solar cell also include molybdate.

[0016] According to some embodiments of the present invention, the molybdate comprises ammonium molybdate.

[0017] According to another aspect of the present invention, a back contact layer material for cadmium telluride solar cells is provided, wherein the raw materials for preparing the material include silver nanowires and molybdate.

[0018] According to some embodiments of the present invention, the molybdate includes at least one of ammonium molybdate or sodium molybdate.

[0019] According to some embodiments of the present invention, the material comprises silver, a complex of silver oxide and silver molybdate.

[0020] According to some embodiments of the present invention, the work function of the back contact layer material is 5.1 to 5.7 eV.

[0021] According to another aspect of the present invention, a method for preparing a back contact layer material for a cadmium telluride solar cell is provided, comprising the following steps:

[0022] A silver nanowire conductive film is prepared by coating the silver nanowire conductive film with an aqueous solution of molybdate; the film is then reacted under an inert atmosphere (nitrogen or an inert gas atmosphere) to obtain the final product.

[0023] According to some embodiments of the present invention, the molar concentration of molybdate ions in the aqueous molybdate solution is 0.04 to 0.16 mol / L.

[0024] According to some embodiments of the present invention, the molar concentration of molybdate ions in the aqueous molybdate solution is 0.1 to 0.15 mol / L.

[0025] According to some embodiments of the present invention, the molybdate includes at least one of ammonium molybdate or sodium molybdate.

[0026] According to some embodiments of the present invention, the reaction conditions include: a reaction temperature of 100–200°C and a reaction time of 0.25–4 h.

[0027] According to some embodiments of the present invention, the reaction conditions include: a reaction temperature of 140–180°C and a reaction time of 0.5–3 h.

[0028] According to some embodiments of the present invention, the reaction conditions include: a reaction temperature of 140–160°C and a reaction time of 0.5–2 h.

[0029] According to some embodiments of the present invention, the reaction conditions further include the addition of a catalyst to the reaction system, said catalyst including a platinum-containing catalyst. Adding a catalyst can shorten the reaction time and improve production efficiency.

[0030] According to some embodiments of the present invention, the catalyst comprises at least one of chloroplatinic acid or chloroauric acid.

[0031] According to some embodiments of the present invention, the preparation method further includes a silver nanowire preparation step, specifically including:

[0032] A surfactant and silver nitrate were mixed and dissolved in a polyol to obtain a solution; a chloride salt was weighed and dissolved in the above solution to obtain a mixed solution; a metal oxide was added to the above mixed solution and reacted to obtain a silver nanowire dispersion.

[0033] Controllable synthesis of silver nanostructures can be achieved in a polyol medium (such as ethylene glycol or glycerol) by reducing a metal salt precursor (such as silver nitrate). This process first utilizes the reducing properties of the polyol to reduce Ag... +Ions are reduced to zero-valent silver atoms, which then nucleate to form initial crystal nuclei with a cubic morphology. These nuclei act as seeds for anisotropic growth, dispersed throughout the reaction system. Their anisotropic surface energy lays the structural foundation for subsequent directional growth. Then, with the help of surfactant molecules (such as polyvinylpyrrolidone, PVP), the nanoparticles grow along a specific direction, resulting in oriented nanomaterials. In the above reaction, commonly used polyvinylpyrrolidone is chosen as the surfactant because it also has selective passivation properties, exhibiting strong coating effects on the {100} crystal planes of silver nanoparticles, while its coating effect on the {111} crystal planes is very weak. This allows silver nanoparticles with added polyvinylpyrrolidone to continue growing along the {111} crystal planes.

[0034] According to some embodiments of the present invention, the surfactant includes polyvinylpyrrolidone (PVP), such as PVP K60.

[0035] Using polyols (such as ethylene glycol and glycerol) as solvents, metal salts (such as silver nitrate) are added, and the reducing properties of the polyols are relied upon to reduce them to elemental nanoparticles. During the precipitation of these nanoparticles, supersymmetric cubic unit cells are generated. These unit cells act as seeds for the growth of silver nanowires, dispersed in the solution. Then, with the help of surfactants, they grow along a specific direction, thus obtaining oriented nanomaterials. For example, polyvinylpyrrolidone is often added as a surfactant in the above reaction. It has a selective passivation effect, strongly coating the {100} crystal planes of silver nanoparticles, but only weakly coating the {111} crystal planes. This allows silver nanoparticles with added polyvinylpyrrolidone to continue growing along the {111} crystal planes, ultimately forming a one-dimensional nanowire structure.

[0036] According to some embodiments of the present invention, the polyol includes at least one of ethylene glycol or glycerol.

[0037] According to some embodiments of the present invention, the metal oxide includes at least one selected from CaO, zinc oxide, nickel oxide, copper oxide, and iron oxide. The addition of the metal oxide prevents the formation of silver particles, which is detrimental to the growth of silver wires.

[0038] According to some embodiments of the present invention, the metal oxide and Ag + The molar ratio is 5 to 15:1. For example, 10:1, etc.

[0039] According to some embodiments of the present invention, the mixed solution contains Cl - With Ag + The molar ratio is 1:50 to 150.

[0040] According to some embodiments of the present invention, the mixed solution contains Cl - With Ag + The molar ratio is 1:90 to 110. For example, 1:100, etc.

[0041] According to another aspect of the present invention, a cadmium telluride solar cell is provided, comprising, in sequence, a substrate layer, a front electrode layer, a window layer, an absorber layer, a back contact layer, and a back electrode layer, wherein the back contact layer is prepared using the aforementioned cadmium telluride solar cell back contact layer material or the cadmium telluride solar cell back contact layer material prepared by the aforementioned method.

[0042] According to some embodiments of the present invention, the front electrode layer is a transparent conductive oxide layer.

[0043] According to some embodiments of the present invention, the transparent conductive oxide layer is an FTO (fluorine-doped SnO2) layer or an ITO (indium tin oxide) layer.

[0044] According to some embodiments of the present invention, the window layer is CdS or CdTe. 1-x Se x layer.

[0045] According to some embodiments of the present invention, the absorption layer is a CdTe layer.

[0046] According to some embodiments of the present invention, the back electrode layer is a metal conductive layer.

[0047] According to some embodiments of the present invention, the metal conductive layer may be a stacked structure formed from one or more of molybdenum, titanium, aluminum, chromium or silver.

[0048] According to some embodiments of the present invention, the cadmium telluride solar cell is further provided with laser trenches.

[0049] According to some embodiments of the present invention, the laser trench includes a P1 laser trench, a P2 laser trench, and a P3 laser trench.

[0050] According to some embodiments of the present invention, the P1 laser trench is formed by cutting the front electrode layer, window layer, absorption layer and back contact layer, and the trench is filled with photoresist.

[0051] According to some embodiments of the present invention, the P1 laser groove is mainly etched using a 355nm ultraviolet laser.

[0052] According to some embodiments of the present invention, the P2 laser trench is formed by cutting the window layer, the absorption layer and the back contact layer, but the front electrode layer is not damaged, and the back electrode layer is filled in the trench.

[0053] According to some embodiments of the present invention, the P2 laser groove is located after the P1 laser groove, with a distance controlled to be 20-80 μm.

[0054] According to some embodiments of the present invention, the P2 laser groove is mainly etched using a green wavelength 532nm laser.

[0055] According to some embodiments of the present invention, the P3 laser trench is mainly formed by cutting the back electrode layer.

[0056] According to some embodiments of the present invention, the P3 laser groove is located after the P2 laser groove, with a distance controlled to be 20-80 μm.

[0057] According to some embodiments of the present invention, the P3 laser groove is to be etched using a green wavelength 532nm laser.

[0058] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of a traditional cadmium telluride thin-film solar cell (the arrows in the diagram indicate the direction of light irradiation).

[0060] Figure 2 This is a schematic diagram of the structure of a new type of cadmium telluride thin-film solar cell in recent years (the arrows in the diagram indicate the direction of light irradiation).

[0061] Figure 3 This is a scanning electron microscope (SEM) image of the silver nanowires prepared in Example 2 of this invention.

[0062] Figure 4 This is a schematic diagram of the structure of the solar cell obtained in Embodiment 6 of the present invention.

[0063] Figure 5 This is a cross-sectional structural diagram of the solar cell chip obtained in Embodiment 7 of the present invention.

[0064] Explanation of reference numerals in the attached figures: 110, substrate layer; 1101, transparent substrate layer;

[0065] 120, front electrode layer; 1201, transparent conductive oxide front electrode layer;

[0066] 130, window layer; 1301, cadmium sulfide window layer; 1302, CdTe 1-x Se x Window layer;

[0067] 140. Absorbing layer; 1401. Cadmium telluride absorbing layer;

[0068] 150, back electrode layer; 1501, metal back electrode layer;

[0069] 160. Back contact layer;

[0070] 1701, P1 laser grooves; 1702, P2 laser grooves; 1703, P3 laser grooves. Detailed Implementation

[0071] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0072] In the description of this invention, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0073] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0074] Example 1

[0075] This example provides a method for fabricating a high work function back contact layer for a cadmium telluride solar cell, including the following steps:

[0076] Step 1: Take the completed cadmium telluride coated chip substrate and clean it. After cleaning, dry the substrate to obtain the cleaned substrate.

[0077] The second step is to perform UV-O3 treatment on the cleaned substrate to obtain a hydrophilic substrate.

[0078] Step 3: Dissolve polyvinylpyrrolidone K60 (PVP K60) and silver nitrate in ethylene glycol at a molar ratio of 1:100, resulting in a silver ion concentration of 0.15 mol / L, to obtain a colorless and transparent solution; then weigh out NaCl and dissolve it in the above solution. + With Ag + The molar ratio of ions is 1:100, resulting in a mixed solution; then, weigh out CaO and add it to the above mixed solution, Ca... 2+ With Ag + A silver nanowire dispersion was prepared with a molar ratio of 10:1.

[0079] Step 4: The silver nanowire dispersion is coated onto the hydrophilicated substrate and dried at 150°C for 2 hours under a nitrogen atmosphere to obtain a silver nanowire conductive film with a thickness of 500 nm.

[0080] Step 5: Take 50-200 mg / ml ammonium molybdate aqueous solution and coat it onto the above-mentioned transparent conductive film of silver nanowires. Dry it at 150°C for 30 min to 3 h under a nitrogen atmosphere to obtain a high-function silver nanowire conductive film with a thickness of 550 nm.

[0081] Example 2

[0082] This example provides a method for fabricating a high work function back contact layer for cadmium telluride solar cells. The back contact layer (silver nanowires) is fabricated after the CdTe absorber layer, primarily to address the issue of poor ohmic contact between the high work function of cadmium telluride and the metal back electrode. The back contact layer material is silver nanowires coated onto the CdTe absorber layer using a chemical solution method. Specifically, the fabrication process is as follows:

[0083] Step 1: Take the completed cadmium telluride coated chip substrate and clean it. After cleaning, dry the substrate to obtain the cleaned substrate.

[0084] The second step is to perform UV-O3 treatment on the cleaned substrate to obtain a hydrophilic substrate.

[0085] Step 3: Dissolve polyvinylpyrrolidone K60 (PVP K60) and silver nitrate in ethylene glycol at a molar ratio of 1:100, resulting in a silver ion concentration of 0.15 mol / L, to obtain a colorless and transparent solution; then weigh out NaCl and dissolve it in the above solution. + With Ag + The molar ratio of ions is 1:100, resulting in a mixed solution; then, weigh out CaO and add it to the above mixed solution, Ca... 2+ With Ag + A silver nanowire dispersion was prepared with a molar ratio of 10:1. (A small amount of the silver nanowire dispersion was coated onto a support, dried at 150℃, and its morphology was observed by scanning electron microscopy. The results are as follows.) Figure 3(as shown);

[0086] Step 4: The silver nanowire dispersion was coated onto a hydrophilized substrate and dried at 150°C for 5 hours under a nitrogen atmosphere to obtain a 500 nm thick conductive silver nanowire film. The work function of the conductive silver nanowire film was measured to be 4.7 eV.

[0087] Step 5: Spin-coat a 50 mg / mL ammonium molybdate aqueous solution onto the above-mentioned transparent conductive silver nanowire film at a spin-coating speed of 3000 r / min and a spin-coating time of 30 s. After drying at 150 °C for 1.5 h under a nitrogen atmosphere, a high work function silver nanowire composite conductive film with a thickness of 550 nm is obtained. The work function of the composite conductive film is measured to be 5.1 eV, which is close to that of cadmium telluride.

[0088] Example 3

[0089] This example provides a method for preparing a high work function back contact layer for a cadmium telluride solar cell. The difference between this method and Example 2 is that the concentration of molybdic acid used in the aqueous solution is 100 mg / mL; the rest is the same as in Example 1.

[0090] The work function of the composite conductive film was measured to be 5.5 eV, which is close to that of cadmium telluride.

[0091] Example 4

[0092] This example provides a method for preparing a high work function back contact layer for a cadmium telluride solar cell. The difference between this method and Example 2 is that the concentration of molybdic acid used in the aqueous solution is 150 mg / mL; the rest is the same as in Example 1.

[0093] The work function of the composite conductive film was measured to be 5.7 eV, which is consistent with that of cadmium telluride.

[0094] Example 5

[0095] This example provides a method for preparing a high work function back contact layer for a cadmium telluride solar cell. The difference between this method and Example 4 is that chloroplatinic acid (concentration 50 mg / mL, addition amount about 60 mL per square meter) is added in the fifth step, and the heat preservation time is 0.5 h; the rest is the same as in Example 1.

[0096] The work function of the composite conductive film was measured to be comparable to that of Example 4.

[0097] Example 6

[0098] This example provides a cadmium telluride solar cell, the structure of which is as follows: Figure 4 As shown, it sequentially includes a substrate layer 110, a front electrode layer 120, a window layer 130, an absorption layer 140, a back contact layer 160, and a back electrode layer 150, wherein the back contact layer is prepared according to the methods of Examples 1 to 5.

[0099] The front electrode layer is a transparent conductive oxide layer, specifically an FTO (fluorine-doped SnO2) layer or an ITO (indium tin oxide) layer.

[0100] The window layer is CdS or CdTe 1-x Se x layer.

[0101] The absorption layer is a CdTe layer.

[0102] The back electrode layer is a metallic conductive layer, which can be a stacked structure formed by one or more of molybdenum, titanium, aluminum, chromium or silver.

[0103] The back contact layer fabricated using the method of this invention has a high work function, which better matches the band structure of the CdTe absorber layer, reduces interfacial band bending, and lowers the hole transport barrier, thereby significantly reducing carrier recombination losses at the back contact. The Voc of the cadmium telluride solar cell with this back contact layer is significantly higher than that of cadmium telluride solar cells with conventional back contact layers. Furthermore, the absence of Cu in this back contact layer reduces problems such as light-induced degradation caused by Cu, improving the long-term stability of the solar cell.

[0104] Example 7

[0105] This example provides a cadmium telluride solar cell chip, the structure of which is as follows: Figure 5 As shown, it sequentially includes a substrate layer 110, a front electrode layer 120, a window layer 130, an absorption layer 140, a back contact layer 160, and a back electrode layer 150, wherein the back contact layer is prepared according to the methods of Examples 1 to 5.

[0106] The cadmium telluride solar cell chip also has two sets of laser grooves on its left and right sides through laser cutting. Each set of laser grooves includes P1 laser groove 1701, P2 laser groove 1702 and P3 laser groove 1703.

[0107] The P1 laser trench is formed by cutting the front electrode layer, window layer, absorption layer and back contact layer, and then filling the trench with photoresist.

[0108] P1 laser trenching is mainly etched using a 355nm ultraviolet laser.

[0109] P2 laser trenching mainly involves cutting the window layer, absorption layer, and back contact layer to form P2 laser trenches, but without damaging the front electrode layer, and filling the trench with the back electrode layer.

[0110] The P2 laser trench follows the P1 laser trench, with a distance control of 20-80 μm.

[0111] P2 laser trenching is mainly etched using a green wavelength 532nm laser.

[0112] P3 laser trenching is mainly formed by cutting the back electrode layer. However, in practice, it is difficult to cut only the back electrode layer without damaging other structural layers. Often in applications, P3 will form laser trenches on the window layer, absorption layer, and back contact layer, and will also damage the front electrode layer, causing perforations.

[0113] The P3 laser trench follows the P2 laser trench, with a distance control of 20-80 μm.

[0114] P3 laser trenches are to be etched using a green wavelength 532nm laser.

[0115] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. Application of silver nanowires in the preparation of the back contact layer of cadmium telluride solar cells.

2. The application according to claim 1, characterized in that: The silver nanowires have a diameter of 25–100 nm and a length of more than 10 μm.

3. The application according to claim 1, characterized in that: The raw materials for preparing the back contact layer of the cadmium telluride solar cell also include molybdate.

4. A cadmium telluride solar cell back contact layer material, characterized in that: The raw materials for preparing the material include silver nanowires and molybdate.

5. The cadmium telluride solar cell back contact layer material according to claim 4, characterized in that: The material contains a complex of silver, silver oxide, and silver molybdate.

6. The cadmium telluride solar cell back contact layer material according to claim 4, characterized in that: The work function of the back contact layer material is 5.1–5.7 eV.

7. A method for preparing a back contact layer material for a cadmium telluride solar cell, characterized in that: Includes the following steps: A silver nanowire conductive film was prepared by coating the silver nanowire conductive film with an aqueous solution of molybdate; the film was then reacted under an inert atmosphere to obtain the final product.

8. The method for preparing the back contact layer material of a cadmium telluride solar cell according to claim 7, characterized in that: The molar concentration of molybdate ions in the aqueous molybdate solution is 0.04–0.16 mol / L.

9. The method for preparing the back contact layer material of a cadmium telluride solar cell according to claim 7, characterized in that: The reaction conditions include: a reaction temperature of 100–200°C and a reaction time of 0.25–4 h.

10. A cadmium telluride solar cell, characterized in that: The material comprises, in sequence, a substrate layer, a front electrode layer, a window layer, an absorber layer, a back contact layer, and a back electrode layer. The back contact layer is prepared using the cadmium telluride solar cell back contact layer material as described in any one of claims 4 to 6 or the cadmium telluride solar cell back contact layer material prepared by the preparation method as described in any one of claims 7 to 9.

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