Transparent electrode, preparation method thereof and solar cell

Abstract

The invention relates to the technical field of solar cells, in particular to a transparent electrode, a preparation method thereof and a solar cell. The first aspect of the embodiment of the invention provides a transparent electrode. The transparent electrode can comprise a three-dimensional conductive network formed by stacking SnO2 coated silver nanowires. Therefore, the composite material has the advantages of remarkably enhanced oxidation corrosion resistance, high conductivity and excellent mechanical flexibility.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to a transparent electrode, its preparation method, and a solar cell. Background Technology

[0002] Perovskite / crystalline silicon tandem solar cells represent a crucial technological path to overcome the Shockley-Quisser theoretical efficiency limit of single-junction cells. Electrodes, as the key functional layer of the device, not only undertake the tasks of carrier collection and transport but also need to possess high light transmittance to reduce optical losses; their performance directly affects the final efficiency and stability of the cell.

[0003] Currently, the use of metal nanowires (such as silver nanowires, Ag NWs) networks as transparent electrodes has been widely studied. However, Ag NWs electrodes have significant drawbacks: in air, especially under the combined effects of humidity, light, and electric field, silver readily reacts with sulfur and oxygen to form silver oxide (Ag₂O) or silver sulfide (Ag₂S), leading to the following problems: 1) Ag₂O is a high-resistivity semiconductor phase (~10⁻⁶). 8 1) The chemical reaction causes nanowires to form a continuous conductive network that can damage the nanowires, increasing the sheet resistance of the electrodes and the series resistance of the battery; 2) The chemical reaction causes nanowires to become porous, broken or fall off, damaging the integrity of the electrode structure and interrupting the carrier transport path; 3) The combined effects lead to rapid and irreversible degradation of battery efficiency, which seriously restricts battery life and commercial applications.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the Invention

[0005] This application provides a transparent electrode, a method for preparing the same, and a solar cell to solve or alleviate one or more of the technical problems mentioned above.

[0006] The first aspect of this application provides a transparent electrode. This transparent electrode may include a three-dimensional conductive network formed by stacked SnO2-coated silver nanowires. This results in significantly enhanced resistance to oxidation and corrosion, high conductivity, and excellent mechanical flexibility.

[0007] A second aspect of this application provides a method for preparing a transparent electrode, comprising the following operations: Provides a dispersion of SnO2-coated silver nanowires; The dispersion was prepared into a wet film using a wet process, and the transparent electrode was obtained after drying.

[0008] The preparation method of this application produces a transparent electrode with uniform composition and no thermal damage.

[0009] A third aspect of this application provides a solar cell, including a transparent electrode from the first aspect of this application or a transparent electrode prepared by the preparation method described in the second aspect of this application. Because this transparent electrode has good conductivity and light transmittance, and stable chemical properties, it is beneficial to improving the performance of the solar cell. Attached Figure Description

[0010] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0011] Figure 1 This is a schematic diagram of the structure of SnO2-coated silver nanowires provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the perovskite single-junction solar cell provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of the perovskite / crystalline silicon tandem solar cell provided in the embodiments of this application.

[0012] Explanation of reference numerals in the attached figures: 101-Top electrode; 102-Electron transport layer; 103-Perovskite light absorption layer; 104-Hole transport layer; 105-Back electrode; 201-Intermediate connection layer; 301-P-type amorphous silicon; 302-Intrinsic amorphous silicon; 303-Silicon substrate; 304-Intrinsic amorphous silicon; 305-N-type amorphous silicon; 306-Transparent conductive oxide layer; 307-Ag electrode. Detailed Implementation

[0013] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0014] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0015] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0016] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0018] The following provides a definition of the terminology used in this application.

[0019] The fill factor (FF) used in this article refers to the actual maximum available power (P). m or V mp *J mp The ratio of the theoretical (not practically available) power (Jsc*Voc) to the theoretical (not practically available) power (Jsc*Voc). Therefore, FF can be determined by the following formula: FF = (V mp *J mp ) / (J sc *V oc Jmp and Vmp represent the current density and voltage at the maximum power point (Pm), respectively, which is obtained by changing the resistance in the circuit until J*V reaches its maximum value; Jsc and Voc represent the short-circuit current and open-circuit voltage, respectively. The fill factor is a key parameter for evaluating solar cells. Commercial solar cells typically have a fill factor of approximately 60% or higher.

[0020] The open-circuit voltage (Voc) used in this paper is the potential difference between the anode and cathode of the device under conditions of no external load connection.

[0021] The short-circuit current (Isc) used in this article is the maximum current flowing through the output terminal of a photovoltaic cell or module when it is short-circuited (voltage V=0) under STC conditions.

[0022] The power conversion efficiency (PCE) of solar cells used in this article refers to the percentage of power converted from absorbed light into electrical energy. The PCE of a solar cell can be measured under standard test conditions (STC) based on incident light irradiance (E: W / m²). 2 ) and the surface area of ​​solar cells (Ac:m 2The STC is calculated by dividing by the point of maximum power (Pm). STC typically refers to the value at a temperature of 25°C and an irradiance of 1000 W / m². 2 The spectrum of air quality 1.5 (AM1.5).

[0023] To improve the stability of Ag NWs, existing technologies have proposed several solutions: 1) using carbon materials such as graphene and carbon nanotubes for coating or composite, utilizing their chemical inertness to achieve physical isolation. However, the contact resistance between carbon materials and silver is high, and absorption exists in the visible light region, which may introduce optical losses and is detrimental to the current matching of tandem batteries; 2) sputtering deposition of metal oxide coatings such as ITO and AZO can form a dense protective layer, but the process requires high vacuum and high temperature, resulting in high cost, and high-energy particles may damage the underlying perovskite active layer; 3) surface treatment or polymer coating, which is simple, but the insulation of polymers increases electrode resistance, and long-term encapsulation reliability also faces challenges in high-temperature and high-humidity environments. The common problem with the above solutions is that they fail to simultaneously achieve "dense and stable encapsulation" and "low-resistance ohmic contact." Often, electrical performance is sacrificed to protect silver from oxidation, or process compatibility and the safety of underlying devices are affected to maintain conductivity. Therefore, developing a new electrode structure that can block corrosive media, maintain or enhance conductivity, and is compatible with tandem battery processes has become an urgent technical challenge to be solved.

[0024] This application provides a transparent electrode, its fabrication method, and a solar cell technology solution. Based on this, it solves the problem of easy oxidation of silver nanowires when used as electrodes. Details are provided below.

[0025] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0026] The first aspect of this application provides a transparent electrode.

[0027] In some embodiments, see Figure 1This transparent electrode can include a three-dimensional conductive network formed by stacked silver nanowires coated with SnO2. This significantly enhances its resistance to oxidation and corrosion. The uniform and complete SnO2 encapsulation layer effectively blocks corrosive media such as oxygen and moisture in the air, preventing the silver nanowires from being oxidized into high-resistivity Ag2O. This maintains the inherent high conductivity of the silver core and the integrity of the network structure, giving the electrode excellent chemical stability and conductive durability in air. Furthermore, it combines high conductivity with excellent mechanical flexibility: the structure integrates the intrinsic flexibility of the silver nanowire network with the mechanical reinforcement of the SnO2 shell. The nanowire network is less prone to brittle fracture when bent, and the SnO2 coating further strengthens the node connections, allowing the electrode to maintain stable conductivity even after repeated bending, making it particularly suitable for flexible tandem batteries. Simultaneously, it enables efficient charge collection and optical matching: the one-dimensional core-shell nanowires form a highly transparent conductive network through overlapping, and SnO2, as a high-mobility N-type semiconductor, forms an ohmic contact with the silver core, synergistically improving carrier extraction efficiency.

[0028] The flexible tandem solar cell possesses bendable or foldable properties. Its tandem structure can be a perovskite / crystalline silicon tandem structure, comprising a perovskite top cell and a crystalline silicon bottom cell, wherein the thickness of the crystalline silicon bottom cell is less than 100 micrometers. Alternatively, the flexible tandem solar cell can be a perovskite / copper indium gallium selenide (CIGS) tandem structure, comprising a perovskite top cell, a CIGS bottom cell, and a flexible substrate. The flexible substrate material can be polyimide, polyethylene naphthalate, stainless steel foil, textile fibers, ultrathin polymer films, etc. This application does not limit the specific structure of the flexible tandem solar cell.

[0029] It should be noted that in the embodiments of this application, SnO2 is continuously and completely coated on the surface of the silver nanowires. This application provides a method for preparing SnO2-coated silver nanowires, including the following steps: Step 1: Mix silver nanowires with a dispersion medium to obtain a silver nanowire dispersion. The concentration of silver nanowires is 0.1~10 mg / mL, and the dispersion medium is at least one of water, ethanol, and acetone. Step 2: Add tin source to the silver-sodium nanowire dispersion, mix well and let stand to obtain SnO2-coated silver nanowire solution. For example, 300-1000 μL of T2E (stannous 2-ethylhexanoate) or SnF2 (stannous fluoride) is added to 40 mL of silver nanowire dispersion, gently shaken to ensure uniform dispersion, and allowed to stand at room temperature to obtain a SnO2-coated silver nanowire solution; during the standing process, Sn... 2+Adsorbed on the surface of silver nanowires, a dense SnO2 coating layer is formed by oxidation with oxygen, as shown in the following reaction formula: Sn 2+ +2H₂O + 0.5O₂ → SnO₂ + 4H + In this embodiment, the reaction at room temperature can avoid damaging the silver nanowire structure, and the system remains stable when left to stand, ensuring that SnO2 can be uniformly nucleated and grown on the surface of the silver nanowires to form a core-shell structured nanocomposite material.

[0030] Step 3: Centrifuge the SnO2-coated silver nanowire solution and wash twice with a dispersion medium. Collect the precipitate to obtain the SnO2-coated silver nanowires. Optionally, the thickness of the SnO2 coating layer is 5 nm to 30 nm. This thickness range ensures consistent coating and good stability and conductivity. If the coating layer thickness is less than 5 nm, it is too thin and provides insufficient protection; if the coating layer thickness is greater than 30 nm, it is too thick and increases resistance, affecting the contact between nanowires. For example, the thickness of the SnO2 coating layer can be 5 nm, 10 nm, 15 nm, 25 nm, 30 nm, etc.

[0031] Optionally, the diameter of the silver nanowires is 20 nm to 100 nm, and the length of the silver nanowires is 10 μm to 50 μm. This provides both light transmittance and conductivity. For example, the diameter of the silver nanowires can be 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, etc. Similarly, the length of the silver nanowires can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, etc.

[0032] In some embodiments, the thickness of the three-dimensional conductive network (i.e., the transparent electrode) is 100 nm to 2 μm. Thus, an ultra-thin electrode layer can achieve excellent conductivity while ensuring effective light transmission from the top cell to the bottom cell in a tandem solar cell, meeting current matching requirements, and achieving a balance between thinning, weight reduction, and efficiency improvement. For example, the thickness of the three-dimensional conductive network (i.e., the transparent electrode) can be 100 nm, 200 nm, 500 nm, 1 μm, 1.2 μm, 1.5 μm, 1.5 μm, 1.8 μm, 2 μm, etc. Preferably, the thickness of the three-dimensional conductive network (i.e., the transparent electrode) is 400 nm to 980 nm.

[0033] In some embodiments, the transparent electrode exhibits a visible light transmittance of over 85% at a wavelength of 550 nm and a sheet resistance of less than 30 Ω / sq. This results in a combination of high conductivity and high transmittance. For example, the transmittance can be 85%, 88%, 90%, 91%, etc., and the sheet resistance can be 24 Ω / sq, 28 Ω / sq, 30 Ω / sq, etc.

[0034] The second aspect of this application provides a method for preparing a transparent electrode.

[0035] The method for using transparent electrodes may include the following steps: S1 provides a dispersion of SnO2-coated silver nanowires; thereby, the SnO2-coated silver nanowires can be uniformly distributed.

[0036] Optionally, the dispersion includes a polar solvent. Further, the polar solvent is selected from one or more of water, ethanol, acetone, isopropanol, methanol, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). A dispersion of SnO2-coated silver nanowires is obtained by mixing SnO2-coated silver nanowires with a polar solvent and then ultrasonically treating the mixture.

[0037] Preferably, the concentration of SnO2-coated silver nanowires in the dispersion is 0.1 mg / mL to 10 mg / mL. This allows for the formation of a continuous and complete conductive network while maintaining good light transmittance. If the concentration exceeds 10 mg / mL, although conductivity may be better, light transmittance will be severely sacrificed (due to the high nanowire density). Simultaneously, the solution viscosity will be too high, hindering uniform coating (e.g., spin coating) and easily leading to excessively thick or uneven films, thus affecting its application in tandem batteries. For example, the concentration of SnO2-coated silver nanowires in the dispersion can be 0.1 mg / mL, 1.5 mg / mL, 2 mg / mL, 3 mg / mL, 5 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, or 10 mg / mL.

[0038] Preferably, the concentration of SnO2-coated silver nanowires in the dispersion is 3 mg / mL to 7 mg / mL. For example, the concentration of SnO2-coated silver nanowires in the dispersion can be 3 mg / mL, 5 mg / mL, 6 mg / mL, or 7 mg / mL. It is understood that the concentration of SnO2-coated silver nanowires in the dispersion refers to the mass concentration of the SnO2-coated silver nanowires, not the sum of the mass concentrations of the silver nanowires and SnO2.

[0039] S2. The dispersion is prepared into a wet film using a wet process, and then dried to obtain the transparent electrode. This results in a transparent electrode with uniform composition.

[0040] Optionally, the wet process may include spin coating, blade coating, spray coating, dip coating, screen printing, slot coating, or inkjet printing.

[0041] The drying process includes annealing at a temperature below 150°C. This avoids thermal damage to the substrate caused by high-temperature processing.

[0042] Preferably, annealing can be performed at 100°C to 150°C for 10 to 60 minutes. For example, the annealing temperature can be 100°C, 120°C, 130°C, 150°C, etc. Similarly, the annealing time can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, etc.

[0043] A third aspect of this application provides a solar cell, including a transparent electrode from the first aspect of this application or a transparent electrode prepared by the preparation method described in the second aspect of this application. Because this transparent electrode has good conductivity and light transmittance, and stable chemical properties, it is beneficial to improving the performance of the solar cell.

[0044] Optionally, the solar cell includes a perovskite single-junction cell or a perovskite tandem cell. Due to the presence of the SnO2 shell, silver ion migration can be effectively suppressed. The dense SnO2 shell acts as a chemically inert barrier, physically isolating the silver nucleus from the perovskite active layer, fundamentally blocking Ag... + The diffusion path to the perovskite layer avoids perovskite material contamination and leakage channel formation, significantly improving the long-term stability of the device under harsh conditions such as high temperature.

[0045] Optionally, the base cell can be a crystalline silicon solar cell, a CIGS thin-film solar cell, a cadmium telluride thin-film solar cell, a III-V thin-film solar cell, or a perovskite solar cell.

[0046] Furthermore, the transparent electrode can be a top electrode, an intermediate connecting layer, or a back electrode.

[0047] In some embodiments, see Figure 2 The solar cell is a perovskite single-junction cell, which includes a top electrode 101, an electron transport layer 102, a perovskite light absorption layer 103, a hole transport layer 104 and a back electrode 105 stacked sequentially; the top electrode 101 can be the transparent electrode described in the first aspect of the embodiments of this application.

[0048] Optionally, the material of the hole transport layer 104 includes nickel oxide (NiO). x Transition metal oxides such as copper oxide (CuO), organic small molecule materials, and polymers such as poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS).

[0049] Among them, small organic molecule materials are usually called SAM (self-assembled monolayer) materials. Common SAM materials include (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl]phosphonic acid (Me-2PACz), [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz), and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-2PACz). -4PACz), [4-(7H-dibenzocarbazole-7-yl)butyl]phosphonic acid (4PADCB), [4-(2,7-dibromo-9,9-dimethylacridin-10(9H)-yl)butyl]phosphonic acid (2Br-4DMAcPA), sodium 4-phenylbutyrate (4-PBA), and 2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanovinyl)phosphonic acid (MPA-CPA) are all small organic molecules. These small organic molecules generally consist of anchoring groups, linking groups, and terminal groups. They can form a monolayer on a substrate surface through self-assembly, thereby regulating interfacial properties, promoting charge transport, and reducing non-radiative recombination.

[0050] Optionally, the electron transport layer 102 can be made of materials including tin dioxide (SnO2), fullerenes (such as C), etc. 60 (and its derivatives PCBM) or specific organic N-type semiconductors. Among them, C 60 Films can be formed via thermal evaporation, while PCBMs are suitable for solution processing. In some specific embodiments, the electron transport layer 102 can be C 60 The stack of layers of C and SnO2, C 60 The layer is located on the side close to the perovskite light-absorbing layer 103.

[0051] Optionally, the perovskite light-absorbing layer 103 material has the general formula ABX3; wherein, the A-site is a monovalent cation selected from methylammonium ion (MA). + ), formamidinium ion (FA) + ), Rb + Cs + One or more combinations thereof; the B site is a divalent metal cation selected from Pb. 2+ Sn 2+ 、Ge 2+ One or more combinations thereof; the X-position is a halide anion selected from Cl. - ,Br - I - One or more combinations of the above.

[0052] Optionally, the back electrode 105 can be a conductive substrate. For example, it can be obtained by fabricating a transparent conductive oxide layer on glass.

[0053] Optionally, the back electrode 105 can be a flexible substrate, such as polyimide (PI), polyester (PET), polyethylene naphthalate (PEN), or metal foil, thus preparing a flexible solar cell.

[0054] In some embodiments, the transparent electrode is further provided with an anti-reflective layer.

[0055] Optionally, the antireflective layer may be made of at least one of magnesium fluoride (MgF2), lithium fluoride (LiF), titanium dioxide (TiO2), silicon dioxide (SiO2), polydimethylsiloxane (PDMS), or perfluoropolyether (PFPE).

[0056] In some embodiments, the solar cell is a perovskite tandem cell. An exemplary structure of a perovskite / heterojunction tandem cell is shown below. Figure 3 The perovskite / heterojunction tandem solar cell includes a top electrode 101, an electron transport layer 102, a perovskite light absorption layer 103, a hole transport layer 104, an intermediate connection layer 201, a P-type amorphous silicon 301, a first intrinsic amorphous silicon 302, a silicon substrate 303, a second intrinsic amorphous silicon 304, an N-type amorphous silicon 305, a transparent conductive oxide layer 306, and an Ag electrode 307, which are stacked sequentially.

[0057] Optionally, the top electrode 101 may be a transparent electrode of the first aspect of the present application embodiments or a transparent electrode obtained by the preparation method of the second aspect of the present application.

[0058] Optionally, the intermediate connecting layer 201 may be a transparent electrode of the first aspect of the present application embodiments or a transparent electrode obtained by the preparation method of the second aspect of the present application.

[0059] The following section will present the fabrication method of the junction perovskite solar cell provided in the embodiments of this application, along with related comparative examples, and will conduct performance tests.

[0060]

Example 1

[0061] Step 2: Load the cleaned substrate into the sputtered NiO plate. The mask, in a vacuum degree below 7×10 -4 Under the condition of Pa, with the radio frequency power set at 400 W and the argon flow rate at 60 sccm, sputtering was performed for 5 minutes to obtain a 20 nm thick NiO layer. Layer 104 serves as the hole transport layer.

[0062] Step 3: Use FA 0.85 MA 0.15 Pb(I 0.95 Br 0.05 As a light-absorbing material, the perovskite precursor material was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 in a nitrogen-atmospheric glove box, and stirred until homogeneous to obtain a precursor solution. A perovskite layer was deposited on the hole transport layer by a two-step spin-coating method. First, the spin-coating was performed at 2500 rpm for 25 seconds, followed by spin-coating at 5500 rpm for 12 seconds. In the second stage, 300 μL of anti-solvent was added dropwise, and then the layer was annealed on a hot stage at 100°C for 30 minutes to form a 450 nm thick perovskite light-absorbing layer 103.

[0063] Step 4: Deposit a 25 nm thick C layer on the perovskite light-absorbing layer 103 using vacuum evaporation. 60 The layer serves as the electron transport layer 102.

[0064] Step 5: Disperse silver nanowires with a diameter of 20 nm to 35 nm and a length of 15 μm to 25 μm in ethanol to prepare a dispersion with a concentration of 1 mg / mL. Take 40 mL of the dispersion, add 300 μL of 2-ethylhexanoate stannous, gently shake and let stand at room temperature to react, to obtain Ag@SnO2 core-shell structure solution, wash and dry to obtain core-shell structured Ag@SnO2, the thickness of SnO2 coating layer is 15 nm; Ag@SnO2 was dispersed in ethanol to prepare a 3 mg / mL dispersion; The dispersion was coated onto the electron transport layer 102 using a spin coating method. First, the spin coating was carried out at a speed of 800 rpm for 10 s, and then at a speed of 2000 rpm for 60 s. Annealing at 130℃ for 30 minutes yielded a transparent electrode with a thickness of 400 nm.

[0065]

Example 2

[0066] The SnO2 coating layer has a thickness of 15 nm; the transparent electrode has a sheet resistance of 18 Ω / sq and a transmittance of 91% at a wavelength of 550 nm.

[0067]

Example 3

[0068]

Example 4

[0069]

Example 5

[0070]

Example 6

[0071]

Example 7

[0072] Step 3: Use FA 0.85 MA 0.15 Pb(I 0.95 Br 0.05 As a light-absorbing material, the perovskite precursor material was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 in a nitrogen-atmospheric glove box, and stirred until homogeneous to obtain a precursor solution. A perovskite layer was deposited on the hole transport layer by a two-step spin-coating method. First, the spin-coating was performed at 2500 rpm for 25 seconds, followed by spin-coating at 5500 rpm for 12 seconds. In the second stage, 300 μL of anti-solvent was added dropwise, and then the layer was annealed on a hot stage at 100°C for 30 minutes to form a 450 nm thick perovskite light-absorbing layer 103.

[0073] Step 4: Deposit a 25 nm thick C layer on the perovskite light-absorbing layer 103 using vacuum evaporation. 60 The layer serves as the electron transport layer 102.

[0074] Step 5: Disperse silver nanowires with a diameter of 20 nm to 35 nm and a length of 15 μm to 25 μm in ethanol to prepare a dispersion with a concentration of 1 mg / mL. Step 6: Take 40 mL of the dispersion, add 300 μL of 2-ethylhexanoate stannous, gently shake and let stand at room temperature to react, to obtain Ag@SnO2 core-shell structure solution, wash and dry to obtain core-shell structured Ag@SnO2; Step 7: Disperse Ag@SnO2 in ethanol to prepare a 3 mg / mL dispersion; Step 8: Spin-coating the dispersion onto the electron transport layer 102. First, spin-coat at 800 rpm for 10 s; then spin at 2000 rpm for 60 s. Annealing at 130℃ for 30 minutes yielded a transparent electrode with a thickness of 400 nm.

[0075] Comparative Example 1 The other steps are the same as in Example 1, except that in step 5 the dispersion is a mixture of silver nanowires and SnO2, specifically: Step 5, Raw material preparation: Select silver nanowires with a diameter of 20 nm to 35 nm and a length of 15 μm to 25 μm as the conductive matrix; SnO2 sol preparation: 300 μL of stannous 2-ethylhexanoate precursor was added to 40 mL of ethanol, gently shaken to dissolve it completely, and allowed to stand at room temperature to form SnO2 sol. Preparation of mixed dispersion: Silver nanowires were added to the SnO2 sol above, and the mass ratio of silver nanowires to SnO2 was controlled to be 10:1. The material was fully dispersed by ultrasonic treatment, and a composite dispersion with a concentration of 3 mg / mL was prepared in ethanol solvent. Film formation process: The obtained composite dispersion was deposited on the surface of the electron transport layer by spin coating. The spin coating program was set as follows: first spin coating at 800 rpm for 10 s to achieve solution spreading, and then spin coating at 2000 rpm for 60 s to control the film thickness. The deposited sample was annealed on a hot plate at 130°C for 30 minutes to form a transparent electrode with a thickness of 400 nm.

[0076] Comparative Example 2 Step 1: A 1.1 mm thick glass substrate is used, on which a 150 nm thick indium tin oxide transparent conductive layer is prepared with a sheet resistance of 15 Ω / sq, which serves as the back electrode 105. Before depositing the functional layer, the substrate is ultrasonically cleaned in ethanol, detergent, ultrapure water, isopropanol and ethanol in sequence, using 500 ml of solvent each time, cleaning for 15 minutes, and finally dried with nitrogen gas for later use.

[0077] Step 2: Load the cleaned substrate into the sputtered NiO plate. The mask, in a vacuum degree below 7×10 -4 Under the condition of Pa, with the radio frequency power set at 400 W and the argon flow rate at 60 sccm, sputtering was performed for 5 minutes to obtain a 20 nm thick NiO layer. Layer 104 serves as the hole transport layer.

[0078] Step 3: Use FA 0.85 MA0.15 Pb(I 0.95 Br 0.05 As a light-absorbing material, the perovskite precursor material was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 in a nitrogen-atmospheric glove box, and stirred until homogeneous to obtain a precursor solution. A perovskite layer was deposited on the hole transport layer by a two-step spin-coating method. First, the spin-coating was performed at 2500 rpm for 25 seconds, followed by spin-coating at 5500 rpm for 12 seconds. In the second stage, 300 μL of anti-solvent was added dropwise, and then the layer was annealed on a hot stage at 100°C for 30 minutes to form a 450 nm thick perovskite light-absorbing layer 103.

[0079] Step 4: Deposit a 25 nm thick C layer on the perovskite light-absorbing layer 103 using vacuum evaporation. 60 The layer serves as the electron transport layer 102.

[0080] Step 5, in C 60 A 120 nm thick ITO transparent conductive layer and a 90 nm thick MgF2 layer were prepared on the layer, followed by printing silver grid lines and sintering to obtain a perovskite single-junction cell.

[0081] Comparative Example 3 The other steps are the same as in Example 7, except that in steps 5 to 8, the steps are directly performed on C. 60 A 120 nm thick ITO transparent conductive layer and a 90 nm thick MgF2 layer were fabricated on the perovskite layer, followed by printing silver grid lines and sintering to obtain a perovskite / crystalline silicon tandem solar cell, as detailed below: Step 1: Provide a crystalline silicon bottom cell, using N-type monocrystalline silicon as the silicon substrate 303. The front side of the silicon substrate 303 is sequentially stacked with a first intrinsic amorphous silicon 302 and a P-type amorphous silicon 301. The back side of the silicon substrate 303 is provided with a second intrinsic amorphous silicon 304, an N-type amorphous silicon 305, an ITO (transparent conductive oxide layer 306), and an Ag electrode 307. The thickness of the crystalline silicon bottom cell is approximately 40 micrometers, and it can be rolled up 360°. Step 2: Fabricate ITO as an intermediate linking layer 301 on P-type amorphous silicon 301; The cleaned substrate is then loaded into a sputtered NiO plate. Using a mask, under vacuum conditions below 7 × 10⁻⁴ Pa, with an RF power of 400 W and an argon flow rate of 60 sccm, sputtering for 5 minutes, a 20 nm thick NiO layer was formed on the intermediate connecting layer 301. Layer 104 serves as the hole transport layer.

[0082] Step 3: Use FA 0.85 MA 0.15 Pb(I 0.95 Br 0.05As a light-absorbing material, the perovskite precursor material was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 in a nitrogen-atmospheric glove box, and stirred until homogeneous to obtain a precursor solution. A perovskite layer was deposited on the hole transport layer by a two-step spin-coating method. First, the spin-coating was performed at 2500 rpm for 25 seconds, followed by spin-coating at 5500 rpm for 12 seconds. In the second stage, 300 μL of anti-solvent was added dropwise, and then the layer was annealed on a hot stage at 100°C for 30 minutes to form a 450 nm thick perovskite light-absorbing layer 103.

[0083] Step 4: A 25 nm thick C60 layer is deposited on the perovskite light-absorbing layer 103 using vacuum evaporation, serving as the electron transport layer 102. Step 5: On C... 60 A 120 nm thick ITO transparent conductive layer and a 90 nm thick MgF2 layer were prepared on the layer, followed by printing silver grid lines and sintering to obtain a perovskite / crystalline silicon tandem solar cell.

[0084] [Test Example] 1. In this application, the sheet resistance of the transparent electrodes of the embodiment and the comparative example was measured using the four-probe method. The average value was taken after measuring 5 different positions for each sample. The results are shown in Table 1.

[0085] 2. Using a UV-Vis spectrophotometer with a blank glass of the same specifications as a reference, the transmittance spectra of the transparent electrodes of the examples and comparative examples in the wavelength range of 300-1100 nm were measured, and the transmittance value at a wavelength of 550 nm was recorded. The results are shown in Table 1.

[0086] 3. The transparent electrodes of the examples and comparative examples were exposed to an indoor atmospheric environment (temperature 25°C ± 5°C, relative humidity 40% ± 10% RH) to simulate normal storage and use conditions. After 500 hours, the sheet resistance of the transparent electrodes was tested and the sheet resistance change rate was calculated. The results are shown in Table 1.

[0087] 4. The solar cells based on the examples and comparative examples were subjected to IV tests, and the results are shown in Table 1.

[0088] 5. The solar cells of Example 7 and Comparative Example 3 were rolled into cylindrical shapes with a bending radius of approximately 33 mm. IV tests were performed before and after rolling to determine the percentage point decrease in cell efficiency after bending compared to before bending. The results are shown in Table 1.

[0089] Table 1:

[0090] Continued from Table 1

[0091] Wherein, the sheet resistance variable rate = (aging sheet resistance - sheet resistance) / sheet resistance × 100%.

[0092] As shown in Table 1 above, the sheet resistance and transmittance of the transparent electrodes in Examples 1-7 are comparable to those of Comparative Example 1. However, the sheet resistance of the transparent electrode in Comparative Example 1 is significantly lower. This is because the Ag nanowires and SnO2 are mixed together without forming a coating on the Ag nanowires, and the Ag nanowires are exposed to air, which leads to oxidation over time, resulting in a significant increase in sheet resistance. This also demonstrates that the SnO2 coating on Ag nanowires in the embodiments of this application significantly improves the stability of the transparent electrode. The IV test data in Table 1 show that the photoelectric conversion efficiency is improved compared to the conventional electrode (Comparative Example 2) using the transparent electrode of the embodiments of this application.

[0093] As shown in Table 1 above, the battery efficiency of the stacked battery in Example 7 decreased by only 0.7 percentage points after being rolled up 360° compared to before rolling, while the battery efficiency of the stacked battery in Comparative Example 3 decreased by 18.2 percentage points after being rolled up 360° compared to before rolling. This shows that the stacked battery in Example 7 has excellent mechanical flexibility.

[0094] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The directional terms "inner" and "outer" refer to the inside or outside relative to the outline of the component itself. For example, if a device in the drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0095] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0096] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0097] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A transparent electrode, characterized in that, It includes a three-dimensional conductive network composed of stacked silver nanowires coated with SnO2.

2. The transparent electrode according to claim 1, characterized in that, The thickness of the SnO2 coating layer is 5 nm to 30 nm; and / or The diameter of the silver nanowire is 20 nm to 100 nm, and the length of the silver nanowire is 10 μm to 50 μm.

3. The transparent electrode according to claim 1, characterized in that, The thickness of the three-dimensional conductive network is 100 nm to 2 μm.

4. The transparent electrode according to claim 1, characterized in that, The transparent electrode has a visible light transmittance of over 85% at a wavelength of 550 nm and a sheet resistance of less than 30 Ω / sq.

5. A method for preparing a transparent electrode, characterized in that, Includes the following operations: Provides a dispersion of SnO2-coated silver nanowires; The dispersion was prepared into a wet film using a wet process, and the transparent electrode was obtained after drying.

6. The method for preparing a transparent electrode according to claim 5, characterized in that, The wet process includes at least one of spin coating, blade coating, spray coating, dip coating, screen printing, slot coating, and inkjet printing; and / or The drying process includes annealing at a temperature below 150°C.

7. The method for preparing a transparent electrode according to claim 5, characterized in that, The dispersion includes a polar solvent; and / or The concentration of SnO2-coated silver nanowires in the dispersion is 0.1 mg / mL to 10 mg / mL.

8. The method for preparing a transparent electrode according to claim 7, characterized in that, The polar solvent is selected from one or more of water, ethanol, acetone, isopropanol, methanol, N,N-dimethylformamide, and dimethyl sulfoxide; and / or The concentration of SnO2-coated silver nanowires in the dispersion is 3 mg / mL to 7 mg / mL.

9. A solar cell, characterized in that, The transparent electrode includes the transparent electrode described in any one of claims 1 to 4 or the transparent electrode prepared by the preparation method described in any one of claims 5 to 8.

10. The solar cell according to claim 9, characterized in that, The solar cells include perovskite single-junction cells or perovskite tandem cells. The transparent electrode is a top electrode, an intermediate connecting layer, or a back electrode.

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