Laminated solar cell and preparation method thereof, power generation device and power utilization device

Abstract

The invention relates to the technical field of photoelectricity, in particular to a laminated solar cell and a preparation method thereof, a power generation device and a power utilization device. The laminated solar cell comprises a top cell, a bottom cell and a middle connecting layer arranged between the top cell and the bottom cell, the middle connecting layer comprises a transparent conductive oxide layer and a doped conductive oxide layer which are stacked, the transparent conductive oxide layer is arranged close to the bottom cell, and the doped conductive oxide layer is arranged close to the top cell; the doped conductive oxide layer is doped with a rare earth element.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, and in particular to a tandem solar cell and its preparation method, power generation device, and power consumption device. Background Technology

[0002] Tandem solar cells can achieve segmented absorption and utilization of the solar spectrum, breaking through the photoelectric conversion efficiency limit of single-junction cells. Therefore, they have become the core technology path to solve the efficiency bottleneck of traditional single-junction solar cells and promote the development of the photovoltaic industry towards high power generation efficiency and low cost.

[0003] In tandem solar cells, transparent conductive oxide layers or tunneling structures are typically used as charge transport and connection bridges between the top and bottom cells. However, the carrier transport layer in the top cell, such as the hole transport layer, needs to be fabricated on the surface of the transparent conductive oxide layer or tunneling structure. Since the transparent conductive oxide layer or tunneling structure surface cannot adequately anchor the carrier transport layer, it can cause the carrier transport layer to gradually diffuse into the perovskite layer during long-term operation. This can damage the integrity of the perovskite crystal and lead to problems such as increased interfacial charge recombination rate, thereby causing a decrease in device efficiency. Summary of the Invention

[0004] Based on this, this application provides a tandem solar cell and its fabrication method, power generation device, and power consumption device. In the tandem solar cell of this application, the anchoring effect formed between the intermediate connecting layer and the top cell can improve the compactness of the carrier transport layer in the top cell, thereby improving the long-term stability of the cell.

[0005] A first aspect of this application provides a tandem solar cell, comprising: a top cell and a bottom cell, and an intermediate connecting layer disposed between the top cell and the bottom cell.

[0006] The intermediate interconnect layer comprises a transparent conductive oxide layer and a doped conductive oxide layer stacked together. The transparent conductive oxide layer is disposed near the bottom cell. The doped conductive oxide layer is disposed near the top cell.

[0007] The doped conductive oxide layer is doped with rare earth elements.

[0008] In some embodiments, the thickness of the doped conductive oxide layer is 1 nm to 10 nm.

[0009] In some embodiments, the sheet resistance of the doped conductive oxide layer is 3000 Ω / sq to 30000 Ω / sq.

[0010] In some embodiments, the carrier mobility of the doped conductive oxide layer is 20 cm⁻¹. 2 / (V·s)~35cm2 / (V·s).

[0011] In some embodiments, the conductive oxide in the doped conductive oxide layer includes one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. The rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium.

[0012] Furthermore, the conductive oxide includes indium tin oxide. The rare earth element includes one or more of cerium and antimony.

[0013] In some embodiments, the mass fraction of the rare earth element in the doped conductive oxide layer is 0.5% to 5%, with the sum of the mass fractions of the rare earth element and the conductive oxide being 100%.

[0014] Furthermore, in the doped conductive oxide layer, with the sum of the mass fractions of the rare earth elements and the conductive oxides being 100%, the mass fraction of the rare earth elements is 3% to 4.5%.

[0015] In some embodiments, the doped conductive oxide layer is a hydrogenated doped conductive oxide layer.

[0016] In some embodiments, the material of the transparent conductive oxide layer includes one or more of indium oxide, indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, and indium gallium zinc oxide.

[0017] In some embodiments, the thickness of the transparent conductive oxide layer is 1 nm to 10 nm.

[0018] In some embodiments, the top cell includes a hole transport layer disposed on the surface of the doped conductive oxide layer, a perovskite layer and an electron transport layer disposed sequentially on the surface of the hole transport layer away from the doped conductive oxide layer.

[0019] In some embodiments, the hole transport layer comprises a self-assembled monolayer. The self-assembled monolayer comprises a self-assembled monomolecular material. The self-assembled monomolecular material comprises one or more of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

[0020] In some embodiments, the bottom battery includes one or more of HJT batteries, TOPCon batteries, and IBC batteries.

[0021] A second aspect of this application provides a method for fabricating a tandem solar cell, comprising the following steps:

[0022] A bottom cell is provided, and a transparent conductive oxide layer and a doped conductive oxide layer are sequentially formed on the surface of the bottom cell to prepare an intermediate connection layer;

[0023] A top battery is formed on the surface of the intermediate connecting layer.

[0024] The doped conductive oxide layer is doped with rare earth elements.

[0025] In some embodiments, the method for preparing the doped conductive oxide layer includes: selecting a rare earth element-doped conductive oxide target and performing physical vapor deposition at a temperature of 55°C to 200°C.

[0026] In some embodiments, the rare earth element-doped conductive oxide target includes one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. The rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium.

[0027] Furthermore, the conductive oxide includes indium tin oxide.

[0028] Furthermore, the rare earth element includes one or more of cerium and antimony.

[0029] In some embodiments, the mass fraction of the rare earth element in the rare earth element-doped conductive oxide target is 0.5% to 5%.

[0030] Furthermore, in the rare earth element-doped conductive oxide target, the mass fraction of the rare earth element is 3% to 4.5%.

[0031] In some embodiments, physical vapor deposition is performed during the preparation of the doped conductive oxide layer in a mixture of inert gas, oxygen, and hydrogen. During the preparation of the doped conductive oxide layer, the volume fraction of hydrogen in the mixture of inert gas, oxygen, and hydrogen is 0.2% to 3%.

[0032] In some embodiments, the sputtering power of the rare earth element-doped conductive oxide target is 2kW to 4kW.

[0033] In some embodiments, the physical vapor deposition temperature is 120°C to 200°C during the preparation of the doped conductive oxide layer.

[0034] In some embodiments, the method for preparing the transparent conductive oxide layer includes: selecting a TCO target and performing physical vapor deposition under conditions of an inert gas, a mixture of oxygen and hydrogen, and a deposition temperature ≤80°C.

[0035] In some embodiments, when preparing the transparent conductive oxide layer, the sputtering power of the TCO target is 2kW~4kW.

[0036] In some embodiments, when preparing the transparent conductive oxide layer, the volume fraction of hydrogen in the mixture of the inert gas, the oxygen, and the hydrogen is 0.2% to 3%.

[0037] In some embodiments, after the step of forming the transparent conductive oxide layer on the surface of the bottom battery and before the step of forming the doped conductive oxide layer, the method further includes: performing ultraviolet ozone pretreatment or plasma pretreatment on the transparent conductive oxide layer.

[0038] The step of performing ultraviolet ozone pretreatment on the transparent conductive oxide layer includes: irradiating the transparent conductive oxide layer with ultraviolet light of 150W~200W, and the ozone concentration in the ultraviolet ozone pretreatment step is 500ppm~3000ppm.

[0039] The step of plasma pretreatment of the transparent conductive oxide layer includes: pretreatment under the conditions of plasma generator power of 250W~1000W, working gas pressure of 10Pa~20Pa, and bias voltage of 50V~100V.

[0040] In some embodiments, the step of forming a top cell on the surface of the intermediate interconnect layer includes:

[0041] A hole transport layer is prepared on the surface of the doped conductive oxide layer in the intermediate interconnect layer;

[0042] A perovskite layer and an electron transport layer are sequentially prepared on the surface of the hole transport layer away from the doped conductive oxide layer.

[0043] In some embodiments, the hole transport layer comprises a self-assembled monolayer, which comprises a self-assembled monomolecule material.

[0044] The method for preparing the self-assembled monolayer includes: dissolving the self-assembled monomolecule material in a solvent to prepare a mixture; coating the mixture onto the surface of the doped conductive oxide layer in the intermediate connecting layer; and performing a solvent removal treatment to prepare the self-assembled monolayer. Optionally, the coating method includes one or more of coating, spin coating, blade coating, and dip-coating.

[0045] A third aspect of this application provides a photovoltaic module, including a tandem solar cell as described in any one of the first aspects of this application or a tandem solar cell prepared by any one of the preparation methods of the second aspect of this application.

[0046] A fourth aspect of this application provides a power generation device, including a tandem solar cell as described in any one of the first aspects of this application or a tandem solar cell prepared by any one of the preparation methods of the second aspect of this application.

[0047] A fifth aspect of this application provides an electrical device comprising a tandem solar cell as described in any one of the first aspects of this application or comprising a tandem solar cell prepared by any one of the preparation methods of the second aspect of this application.

[0048] The beneficial effects of the above-mentioned tandem solar cells are as follows:

[0049] In the tandem solar cell provided in this application, a transparent conductive oxide layer disposed near the bottom cell and a rare-earth-doped conductive oxide layer disposed near the top cell form a compositionally matched intermediate connecting layer structure. The transparent conductive oxide layer not only prevents carrier recombination at the bottom cell interface but also buffers the stress difference between the doped conductive oxide layer and the bottom cell. The doped conductive oxide layer can construct numerous active anchoring sites at the contact interface between the doped conductive oxide layer and the top cell. Therefore, the gradient structure in the intermediate connecting layer provided in this application achieves functional complementarity at the composition level. The active anchoring sites of the doped conductive oxide layer can form a dual effect of chemical bonding and physical adsorption with the precursor molecules of the carrier transport layer in the top cell, guiding the orderly formation of molecules, inhibiting particle aggregation and pore defects, thereby improving the compactness of the carrier transport layer of the top cell and providing structural support for the long-term stability of the cell. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of a tandem solar cell provided as an example of this application.

[0051] Figure 2 This is an XRD pattern of the doped conductive oxide layer obtained in Example 1 of this application.

[0052] Figure 3 This is an XRD pattern of the doped conductive oxide layer obtained in Example 2 of this application.

[0053] Explanation of reference numerals in the attached figures

[0054] 1. Tandem solar cell; 10. Top cell; 110. Hole transport layer; 120. Perovskite layer; 130. Electron transport layer; 140. First TCO layer; 150. First electrode layer; 20. Bottom cell; 210. Silicon substrate; 220. First intrinsic amorphous silicon layer; 230. Second intrinsic amorphous silicon layer; 240. N-type silicon layer; 250. P-type silicon layer; 260. Second TCO layer; 270. Second electrode layer; 30. Intermediate connecting layer; 310. Transparent conductive oxide layer; 320. Doped conductive oxide layer. Detailed Implementation

[0055] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0056] In this article, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "options" in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "option" is independent.

[0057] In this document, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0059] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0060] In this article, "at least one" means one or more, such as one, two or more. "Multiple" or "several" means at least two, such as two, three, etc.

[0061] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that 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 herein should be understood to include any and all subranges included therein. The "numerical value" in this 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, and other numerical interval types.

[0062] Unless otherwise specified, all percentage concentrations mentioned in this article refer to the final concentration. The final concentration refers to the proportion of the added ingredient in the system after the addition of that ingredient.

[0063] The fill factor (FF) used in this paper refers to the ratio of the actual maximum obtainable power (Pm or Vmp * Jmp) to the theoretical (not actually obtainable) power (Jsc * Voc). Therefore, FF can be determined by the following formula:

[0064] FF = (Vmp * Jmp) / (Jsc * Voc).

[0065] Where 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.

[0066] 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.

[0067] 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 2 The 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).

[0068] In this document, for methods involving multiple steps, unless otherwise explicitly stated herein, there is no strict order constraint on the execution of these steps; they may be executed in any order other than those described. Moreover, any step may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed in turn, alternately, or simultaneously with other steps or parts of the sub-steps or stages of other steps.

[0069] Among various tandem solar cell systems, perovskite / crystalline silicon tandem solar cells, using perovskite materials as the top cell, have attracted significant attention due to the unique advantages of perovskite top cells. Perovskite top cells possess a suitable bandgap width (1.5~1.7 eV), enabling efficient absorption of the ultraviolet-visible portion of the solar spectrum, which complements the near-infrared absorption of crystalline silicon bottom cells, achieving efficient utilization of the entire spectrum. Furthermore, perovskite materials offer advantages such as simple fabrication processes, low film-forming temperatures, high carrier mobility, and large optical absorption coefficients. These advantages not only reduce the fabrication cost of tandem solar cells but also allow for large-area fabrication on flexible substrates, expanding the application scenarios of solar cells.

[0070] However, the structural design of tandem solar cells still has significant flaws, limiting the long-term stable operation of the devices. Specifically, the carrier transport layer (such as the hole transport layer) of the top cell needs to be directly deposited on the surface of a transparent conductive oxide layer or a tunnel junction structure. However, the surface of traditional transparent conductive oxide layers or tunnel junction structures lacks effective active anchoring sites, making it impossible to form stable bonds with the precursor molecules of the carrier transport layer. This makes it difficult to effectively anchor and constrain the film formation process and subsequent service state of the carrier transport layer. Under these circumstances, during long-term operation of the perovskite top cell, the molecules in the carrier transport layer will gradually diffuse, eventually forming a non-dense layer, thus causing a decrease in device efficiency.

[0071] Based on this, the first aspect of this application, as Figure 1 As shown, a tandem solar cell 1 is provided, including: a top cell 10 and a bottom cell 20, and an intermediate connecting layer 30 disposed between the top cell 10 and the bottom cell 20.

[0072] The intermediate connection layer 30 includes a transparent conductive oxide layer 310 and a doped conductive oxide layer 320 stacked together. The transparent conductive oxide layer 310 is disposed near the bottom cell 20. The doped conductive oxide layer 320 is disposed near the top cell 10. In other words, the transparent conductive oxide layer 310 is located between the bottom cell 20 and the doped conductive oxide layer 320.

[0073] In some of these examples, the doped conductive oxide layer 320 is doped with rare earth elements. In other words, the doped conductive oxide layer 320 comprises a conductive oxide doped with rare earth elements.

[0074] The doped conductive oxide layer 320 in this application differs from the transparent conductive oxide layer 310. The "transparent conductive oxide layer 310" in this application does not include rare earth elements.

[0075] In the tandem solar cell 1 provided in this application, a transparent conductive oxide layer 310 disposed near the bottom cell 20 and a rare-earth-doped conductive oxide layer 320 disposed near the top cell 10 form an intermediate connecting layer 30 structure with a composition gradient matching. The transparent conductive oxide layer 310 prevents carrier recombination at the interface with the bottom cell, and its flexible interface buffers the interfacial stress caused by lattice parameter differences between the doped conductive oxide layer 320 and the bottom cell, preventing interface cracking or peeling and ensuring the structural bonding stability of the intermediate connecting layer 30 and the bottom cell.

[0076] In some examples, the doped conductive oxide layer 320 is a rare earth element-doped conductive oxide. In this case, the active hydrogen groups and rare earth element dopant in the doped conductive oxide layer 320 can jointly regulate the lattice arrangement of the doped conductive oxide layer 320, promoting the formation of numerous active sites in the lattice. Simultaneously, the active hydrogen groups can undergo a controllable reaction with oxygen atoms in the metal oxide lattice to generate hydroxyl groups. The regulatory effect of rare earth element doping on the lattice arrangement, as well as the difference in distribution between the crystalline and amorphous regions of the doped conductive oxide layer 320 itself, restricts the continuous attachment of hydroxyl groups across the entire surface, causing them to selectively bond only at the active sites in the lattice. This introduces discontinuous active regions rich in covalently bonded hydroxyl groups into the doped conductive oxide layer 320. These discontinuous hydroxyl active regions can enhance the coverage and bonding strength of the carrier transport layer molecules at the interface in the perovskite top cell, ultimately constructing numerous active anchoring points at the contact interface between the doped conductive oxide layer 320 and the top cell.

[0077] Therefore, the gradient structure in the intermediate connection layer 30 provided in this application achieves functional complementarity. The active anchoring sites of the doped conductive oxide layer 320 can form a dual effect of chemical bonding and physical adsorption with the precursor molecules of the charge carrier transport layer in the top cell 10, guiding the precursor molecules to arrange and grow in an orderly manner at the interface, inhibiting particle aggregation and pore defects during film formation, thereby improving the compactness of the charge carrier transport layer of the top cell.

[0078] In some examples, the conductive oxide layer 320 includes one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. Optionally, rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium. Further, the conductive oxide includes indium tin oxide. Rare earth elements include one or more of cerium and antimony.

[0079] As an example, assuming the sum of the mass fractions of rare earth elements and conductive oxides is 100%, the mass fraction of rare earth elements is 0.5% to 5%. That is, in the doped conductive oxide layer 320, rare earth elements account for 0.5% to 5% of the total mass of rare earth elements and conductive oxides. Since the target material used in the doped conductive oxide layer 320 is composed of rare earth elements and conductive oxides, the mass fraction of rare earth elements in the target material is 0.5% to 5%. Therefore, in the doped conductive oxide layer 320 obtained in this way, assuming the sum of the mass fractions of rare earth elements and conductive oxides is 100%, the mass fraction of rare earth elements is 0.5% to 5%.

[0080] As an example, in the doped conductive oxide layer 320, the mass fraction of rare earth elements in the total mass of rare earth elements and conductive oxides includes, but is not limited to, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.2%, 3.5%, 4%, 4.5%, or 5%, or any two of the above values ​​as endpoints. Further, in the doped conductive oxide layer 320, rare earth elements account for 1.5% to 5% of the total mass of rare earth elements and conductive oxides. Even further, in the doped conductive oxide layer 320, rare earth elements account for 3% to 4.5% of the total mass of rare earth elements and conductive oxides. That is, with the sum of the mass fractions of rare earth elements and conductive oxides being 100%, the mass fraction of rare earth elements is 3% to 4.5%.

[0081] The aforementioned doped conductive oxide layer 320 uses high-performance transparent conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO) as substrates and is doped with rare earth elements. It has high light transmittance, excellent carrier transport capability and stable interface anchoring activity, and can efficiently adapt to the functional requirements of the intermediate connection layer 30 of perovskite / crystalline silicon tandem solar cells.

[0082] In some examples, the sheet resistance of the doped conductive oxide layer 320 is 3000 Ω / sq to 30000 Ω / sq. The carrier mobility of the doped conductive oxide layer is 20 cm⁻¹. 2 / (V·s)~35cm 2 / (V·s).

[0083] In this application, "sheet resistance" refers to the sheet resistance, which is the resistance value per unit area of ​​the doped conductive oxide layer 320, and its unit is Ω / sq (ohms per square). This value reflects the conductivity and carrier transport characteristics of the thin film. As an example, "sheet resistance" can be measured by the four-point probe method.

[0084] In this application, "carrier mobility" refers to the ratio of the drift velocity of the doped conductive oxide layer 320 under electric field driving to the electric field strength, with units of cm. 2 / (V·s). As an example, "carrier mobility" can be obtained by using a Hall effect tester and the van der Berg method at room temperature.

[0085] The sheet resistance and carrier mobility of the doped conductive oxide layer 320 provided in this application are similar to those of the transparent conductive oxide layer 310. The two work together to construct an intermediate connecting layer with a smooth transition in electrical performance, effectively reducing the risk of carrier recombination at the interface and buffering the stress difference between layers. At the same time, the active anchoring points provided by rare earth doping can optimize the film quality of the carrier transport layer of the top cell, providing support for the high-efficiency photoelectric conversion and long-term stability of the tandem solar cell.

[0086] To balance interface anchoring activity, carrier transport efficiency, and light transmittance, and to avoid light loss and increased resistance due to a slightly thicker doped conductive oxide layer 320, or insufficient anchoring points and decreased interface stability due to a slightly thinner doped conductive oxide layer 320, the thickness of the doped conductive oxide layer 320 is 1 nm to 10 nm in some examples. For example, the thickness of the doped conductive oxide layer 320 includes, but is not limited to, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 10 nm, or any two of the above values ​​as endpoints.

[0087] In some of these examples, the material of the transparent conductive oxide layer 310 includes one or more of indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and indium gallium zinc oxide (IGZO).

[0088] In some of these examples, the thickness of the transparent conductive oxide layer 310 is 1 nm to 10 nm.

[0089] The following description, in conjunction with the preparation method, further illustrates the differences between the transparent conductive oxide layer 310 and the doped conductive oxide layer 320, as well as preferred examples of the doped conductive oxide layer 320.

[0090] In some examples, the method for preparing the doped conductive oxide layer 320 includes: selecting a rare-earth element-doped conductive oxide target and performing physical vapor deposition at a temperature of 55°C to 200°C. Furthermore, to obtain a hydrogenated doped conductive oxide layer, the physical vapor deposition is further performed in a mixture of inert gas, oxygen, and hydrogen during the preparation of the doped conductive oxide layer 320.

[0091] Further, the sputtering power of the rare earth element-doped conductive oxide target is 2kW~4kW. The mass fraction of rare earth elements in the rare earth element-doped conductive oxide target is 0.5%~5%. Further, the mass fraction of rare earth elements in the rare earth element-doped conductive oxide target is 3%~4.5%. When preparing the doped conductive oxide layer 320, the volume fraction of hydrogen in the mixture of inert gas, oxygen, and hydrogen is 0.2%~3%. More further, the volume fraction of inert gas in the mixture is 90%~95%, the volume fraction of oxygen is 3%~7%, and the volume fraction of hydrogen is 0.2%~3%. In this example, the conductive oxide target includes, but is not limited to, one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. Rare earth elements include, but are not limited to, one or more of cerium, antimony, yttrium, and gadolinium. Further, the conductive oxide target includes, but is not limited to, indium tin oxide. Rare earth elements include, but are not limited to, one or more of cerium and antimony.

[0092] In this example, the physical vapor deposition temperature includes, but is not limited to, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any two of the above values ​​as endpoints. The mass fraction of rare earth elements in the rare earth-doped conductive oxide target includes, but is not limited to, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.2%, 3.5%, 4%, 4.5%, or 5%, or any two of the above values ​​as endpoints. The volume fraction of inert gas in the mixed gas includes, but is not limited to, 90%, 91%, 92%, 92.3%, 92.34%, 92.35%, 92.4%, 93%, 94%, or 95%. The volume fraction of oxygen includes, but is not limited to, 3%, 4%, 5%, 6%, or 7%. The volume fraction of hydrogen includes, but is not limited to, 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 2.6%, 2.65%, 2.66%, 2.7% or 3%.

[0093] Understandably, the preparation of the doped conductive oxide layer 320 involves physical vapor deposition at high temperatures without the need for an additional annealing step. This application discovers that, compared to annealing after deposition, the in-situ high-temperature deposition process of this application can simultaneously complete crystal growth and defect repair during film formation. This avoids the accumulation of film stress, interface diffusion, and damage to the interlayer structure of the device caused by high-temperature annealing, while simplifying the preparation process and shortening the production cycle. Simultaneously, it ensures that the doped conductive oxide layer possesses high crystal integrity and stable electrical properties, providing a guarantee for the efficient carrier transport and long-term reliability of tandem solar cells.

[0094] Furthermore, the physical vapor deposition temperature is 120℃~200℃. This application has found that if the physical vapor deposition temperature is below 120℃, although the sheet resistance and carrier mobility of the doped conductive oxide layer 320 do not change significantly after deposition, the microstructure of the doped conductive oxide layer 320 obtained by low-temperature deposition, such as crystallinity and grain order, is inferior to that obtained by physical vapor deposition at 120℃~200℃.

[0095] Understandably, in the preparation process of the doped conductive oxide layer in this application, the deposition process is carried out at a temperature of 120°C to 200°C, and no annealing is required after physical vapor deposition. This application has found that when the doped conductive oxide layer is deposited at a temperature of 120°C to 200°C, the doped conductive oxide layer prepared at this temperature tends to promote the formation of microcrystals in some areas, without excessive growth or lattice distortion, while simultaneously achieving improved carrier mobility and reduced film roughness. Furthermore, this step avoids the thermal desorption of hydroxyl groups caused by additional annealing. At this time, active hydrogen groups can be released by relying on the relatively high hydrogen content in the doped conductive oxide layer 320. These active hydrogen groups, together with the rare earth element doping components and the specific crystallinity of the doped conductive oxide layer 320, control the lattice arrangement, which promotes the formation of a large number of active sites in the lattice. Moreover, the active hydrogen groups react with oxygen atoms in the metal oxide lattice in a controllable manner to generate hydroxyl groups, thereby introducing discontinuous active regions rich in covalently bonded hydroxyl groups into the doped conductive oxide layer 320. This enhances the coverage and binding strength of the carrier transport layer molecules to the interface in the perovskite top cell, and finally constructs a large number of active anchoring points at the contact interface between the doped conductive oxide layer 320 and the top cell.

[0096] Furthermore, during the preparation of the doped conductive oxide layer 320, the physical vapor deposition temperature is 120℃~180℃.

[0097] In some examples, the preparation steps of the transparent conductive oxide layer 310 include: selecting a TCO target and performing physical vapor deposition under a mixed atmosphere of inert gas, oxygen, and hydrogen, and a deposition temperature ≤80°C. During the physical vapor deposition of the transparent conductive oxide layer, the sputtering power of the TCO target is 2kW~4kW. In this example, the volume fraction of hydrogen in the mixed atmosphere of inert gas, oxygen, and hydrogen is 0.2%~3%. Further, in this example, the volume fraction of inert gas in the mixed atmosphere is 95.5%~98%, the volume fraction of oxygen is 0.5%~2.5%, and the volume fraction of hydrogen is 0.2%~3%. In this example, the TCO target includes, but is not limited to, one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. In this example, the deposition temperature includes, but is not limited to, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C, or any two of the above values ​​as endpoints. In this example gas mixture, the volume fraction of the inert gas includes, but is not limited to, 95.5%, 96%, 96.1%, 96.2%, 96.5%, 97%, 97.5%, or 98%. The volume fraction of oxygen includes, but is not limited to, 0.5%, 0.8%, 1%, 1.5%, 1.8%, 1.9%, 2%, 2.1%, or 2.5%. The volume fraction of hydrogen includes, but is not limited to, 0.2%, 0.5%, 1%, 1.5%, 1.8%, 2%, 2.5%, or 3%.

[0098] Understandably, the main differences between the preparation steps of the transparent conductive oxide layer 310 and the doped conductive oxide layer 320 lie in the presence or absence of rare earth element doping and the different deposition temperatures during the deposition process. Furthermore, the proportions of inert gas and oxygen gas differ during deposition. Through differentiated control of these process parameters, the two layers exhibit different properties in terms of crystallinity and surface active sites.

[0099] The different setup of the preparation steps of the transparent conductive oxide layer 310 and the doped conductive oxide layer 320 allows for precise matching of the interface requirements of the bottom cell side and the top cell side, enabling the two conductive oxide layers to form a gradient complementary structure in terms of crystallinity and surface active sites. This ensures low interfacial recombination and stress buffering on the bottom cell side, while achieving high film quality and carrier transport stability on the top cell side, ultimately improving the overall photoelectric conversion efficiency and long-term operational reliability of the tandem solar cell.

[0100] In some examples, the top cell 10 includes a hole transport layer 110 disposed on the surface of the doped conductive oxide layer 320, and a perovskite layer 120 and an electron transport layer 130 disposed on the hole transport layer 110 away from the surface of the doped conductive oxide layer 320.

[0101] Optionally, the hole transport layer 110 includes a self-assembled monolayer. The self-assembled monolayer includes a self-assembled monomolecular material. The self-assembled monomolecular material includes one or more of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

[0102] When the hole transport layer 110 is disposed on the surface of the doped conductive oxide layer 320, it can form a strong covalent bond with the discontinuous hydroxyl active regions on the surface of the doped conductive oxide layer 320. The active sites on the surface of the doped conductive oxide layer 320 can also enhance the interfacial bonding strength between the hole transport layer 110 and the doped conductive oxide layer 320, preventing interfacial peeling or detachment during long-term service. At the same time, this composite structure can further optimize the film formation orientation of the carrier transport layer precursor molecules in the top cell, guide the orderly growth of molecules, and suppress particle aggregation and pore defects, thereby synergistically improving the photoelectric conversion efficiency and long-term stability of the tandem cell.

[0103] In some examples, the perovskite material included in the perovskite layer 120 has the structural formula ABX3. Here, A includes one or more of methylamine ions, dimethylamine ions, formamidinium ions, acetamidine ions, cesium ions, rubidium ions, and guanidine ions. B includes one or more of lead ions, tin ions, and germanium ions. X includes one or more of bromide ions, iodide ions, chloride ions, thiocyanate ions, tetrafluoroborate ions, and hexafluoroborate ions. Further, the thickness of the perovskite layer 120 is 10 nm to 100 nm.

[0104] In some examples, the electron transport layer 130 is made of one or more of tin oxide, titanium oxide, zinc oxide, zirconium oxide, magnesium oxide, zinc gallium oxide, indium zinc oxide, fluorine-doped tin oxide, and indium tin oxide. Further, the thickness of the electron transport layer 130 is 3 nm to 50 nm.

[0105] In some examples, the top cell 10 further includes a first TCO layer 140. The first TCO layer 140 is disposed on the side surface of the electron transport layer 130 opposite to the perovskite layer 120.

[0106] As a further example, the material of the first TCO layer 140 includes one or more of ITO, IZO, IWO, FTO, ICO, AZO, ATO, and GZO. As an even further example, the thickness of the first TCO layer 140 is 20 nm to 100 nm.

[0107] The primary function of the first TCO layer 140 is to serve as the top electrode of the top cell 10. It allows sunlight to penetrate to the perovskite layer 120 for absorption and rapidly collects and leads outward photogenerated carriers generated by the top cell. Furthermore, the first TCO layer 140 exhibits an average transmittance ≥90% and a haze ≤2% in the 300nm~800nm ​​range. Understandably, this application does not limit the hydrogen doping amount or crystallinity of the first TCO layer 140, as long as the average transmittance and haze are within the aforementioned ranges.

[0108] In some examples, the top cell 10 further includes a first electrode layer 150. The first electrode layer 150 is disposed on the surface of the first TCO layer 140 facing away from the electron transport layer 130. The material of the first electrode layer 150 includes, but is not limited to, one or more of copper (Cu), aluminum (Al), silver (Ag), nickel (Ni), cobalt (Co), gold (Au), molybdenum (Mo), or chromium (Cr). Further, the thickness of the first electrode layer 150 is 100 nm to 20 μm.

[0109] In some of these examples, the bottom battery 20 includes one or more of HJT batteries, TOPCon batteries, and IBC batteries.

[0110] As an example, the bottom cell 20 includes: a silicon substrate 210 having a first surface and a second surface disposed opposite to each other; an intrinsic amorphous silicon layer including a first intrinsic amorphous silicon layer 220 and a second intrinsic amorphous silicon layer 230, the first intrinsic amorphous silicon layer 220 being disposed on the first surface and the second intrinsic amorphous silicon layer 230 being disposed on the second surface; an N-type silicon layer 240 disposed on the surface of the first intrinsic amorphous silicon layer 220 opposite to the silicon substrate 210; and a P-type silicon layer 250 disposed on the surface of the second intrinsic amorphous silicon layer 230 opposite to the silicon substrate 210.

[0111] In some examples, the bottom cell 20 further includes a second TCO layer 260. The second TCO layer 260 is disposed on the surface of the p-type silicon layer 250 opposite to the second intrinsic amorphous silicon layer 230. Further, the material of the second TCO layer 260 includes one or more of ITO, IZO, IWO, FTO, ICO, AZO, ATO, and GZO. Even further, the thickness of the second TCO layer 260 is 20 nm to 100 nm.

[0112] The primary function of the second TCO layer 260 is to serve as the back electrode of the bottom cell 20. It reflects long-wavelength sunlight penetrating the top cell back to the crystalline silicon active layer of the bottom cell to improve light absorption efficiency, and also efficiently collects photogenerated carriers generated by the bottom cell and leads them outwards. Furthermore, the second TCO layer 260 exhibits an infrared reflectivity ≥85% and a sheet resistance ≤10Ω / sq in the 800nm~1200nm range. Understandably, this application does not limit the type of doped elements or surface morphology of the second TCO layer 260, as long as the infrared reflectivity and sheet resistance are within the aforementioned ranges.

[0113] In some examples, the bottom cell 20 further includes a second electrode layer 270. The second electrode layer 270 is disposed on the surface of the second TCO layer 260 opposite to the p-type silicon layer 250. The material of the second electrode layer 270 includes, but is not limited to, one or more of copper (Cu), aluminum (Al), silver (Ag), nickel (Ni), cobalt (Co), gold (Au), molybdenum (Mo), or chromium (Cr). Further, the thickness of the second electrode layer 270 is 100 nm to 20 μm.

[0114] A second aspect of this application provides a method for fabricating a tandem solar cell 1, comprising the following steps:

[0115] S10: Provides a bottom battery 20.

[0116] S20: A transparent conductive oxide layer 310 and a doped conductive oxide layer 320 are sequentially formed on the surface of the bottom cell 20 to prepare an intermediate connection layer 30. The doped conductive oxide layer 320 is doped with rare earth elements.

[0117] S30: A top cell 10 is formed on the surface of the intermediate connecting layer 30.

[0118] In some of these examples, in step S10, the bottom battery 20 includes one or more of HJT batteries, TOPCon batteries, and IBC batteries.

[0119] As an example, the bottom cell 20 includes: a silicon substrate 210 having a first surface and a second surface disposed opposite to each other; an intrinsic amorphous silicon layer including a first intrinsic amorphous silicon layer 220 and a second intrinsic amorphous silicon layer 230, the first intrinsic amorphous silicon layer 220 being disposed on the first surface and the second intrinsic amorphous silicon layer 230 being disposed on the second surface; an N-type silicon layer 240 disposed on the side of the first intrinsic amorphous silicon layer 220 opposite to the silicon substrate 210; and a P-type silicon layer 250 disposed on the side of the second intrinsic amorphous silicon layer 230 opposite to the silicon substrate 210. Further, in step S20, a transparent conductive oxide layer 310 and a doped conductive oxide layer 320 are sequentially formed on the surface of the N-type silicon layer 240 in the bottom cell 20.

[0120] In some examples, in step S10, the bottom cell 20 further includes a second TCO layer 260. The second TCO layer 260 is disposed on the surface of the p-type silicon layer 250 opposite to the second intrinsic amorphous silicon layer 230. Further, the preparation method of the second TCO layer 260 includes: selecting a TCO target material, using an argon flow rate of 100 sccm to 500 sccm, an oxygen flow rate of 5 sccm to 20 sccm, and a power of 1.5 kW to 2.5 kW. The selected TCO target material includes, but is not limited to, one or more of indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and indium gallium zinc oxide (IGZO).

[0121] In some examples, in step S10, the bottom cell 20 further includes a second electrode layer 270. The second electrode layer 270 is disposed on the surface of the second TCO layer 260 facing away from the P-type silicon layer 250.

[0122] The materials, thicknesses, etc. of each functional layer in the bottom battery 20 of the second aspect of this application are the same as those in the first aspect of this application, so they will not be repeated here.

[0123] In some examples, the method for preparing the doped conductive oxide layer 320 includes: selecting a rare-earth element-doped conductive oxide target and performing physical vapor deposition at a temperature of 55°C to 200°C. Furthermore, to obtain a hydrogenated doped conductive oxide layer, the physical vapor deposition is further performed in a mixture of inert gas, oxygen, and hydrogen during the preparation of the doped conductive oxide layer 320.

[0124] Further, the sputtering power of the rare earth element-doped conductive oxide target is 2kW~4kW. The mass fraction of rare earth elements in the rare earth element-doped conductive oxide target is 0.5%~5%. Further, the mass fraction of rare earth elements in the rare earth element-doped conductive oxide target is 3%~4.5%. When preparing the doped conductive oxide layer 320, the volume fraction of hydrogen in the mixture of inert gas, oxygen, and hydrogen is 0.2%~3%. More further, the volume fraction of inert gas in the mixture is 90%~95%, the volume fraction of oxygen is 3%~7%, and the volume fraction of hydrogen is 0.2%~3%. The rare earth element-doped conductive oxide target includes rare earth elements and conductive oxides. Rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium. In this example, the conductive oxide target includes, but is not limited to, one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. Further, rare earth elements include, but are not limited to, one or more of cerium and antimony. Conductive oxide targets include, but are not limited to, indium tin oxide.

[0125] In this example, the physical vapor deposition temperature includes, but is not limited to, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any two of the above values ​​as endpoints. The mass fraction of rare earth elements in the rare earth-doped conductive oxide target includes, but is not limited to, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.2%, 3.5%, 4%, 4.5%, or 5%, or any two of the above values ​​as endpoints. The volume fraction of inert gas in the mixed gas includes, but is not limited to, 90%, 91%, 92%, 92.3%, 92.34%, 92.35%, 92.4%, 93%, 94%, or 95%. The volume fraction of oxygen includes, but is not limited to, 3%, 4%, 5%, 6%, or 7%. The volume fraction of hydrogen includes, but is not limited to, 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 2.6%, 2.65%, 2.66%, 2.7% or 3%.

[0126] Understandably, the preparation of the doped conductive oxide layer 320 involves physical vapor deposition at high temperatures without the need for an additional annealing step. This application discovers that, compared to annealing after deposition, the in-situ high-temperature deposition process of this application can simultaneously complete crystal growth and defect repair during film formation. This avoids the accumulation of film stress, interface diffusion, and damage to the interlayer structure of the device caused by high-temperature annealing, while simplifying the preparation process and shortening the production cycle. Simultaneously, it ensures that the doped conductive oxide layer possesses high crystal integrity and stable electrical properties, providing a guarantee for the efficient carrier transport and long-term reliability of tandem solar cells.

[0127] Furthermore, during the preparation of the doped conductive oxide layer 320, the physical vapor deposition temperature is 120℃~200℃. This application has found that if the physical vapor deposition temperature is lower than 120℃, although the sheet resistance and carrier mobility of the doped conductive oxide layer 320 do not change significantly after deposition, the microstructure of the doped conductive oxide layer 320 obtained by low-temperature deposition, such as crystallinity and grain order, is inferior to that obtained by physical vapor deposition at 120℃~200℃.

[0128] Understandably, in the preparation process of the doped conductive oxide layer in this application, the deposition process is carried out at a temperature of 120°C to 200°C, and no annealing is required after physical vapor deposition. This application has found that when the doped conductive oxide layer is deposited at a temperature of 120°C to 200°C, the doped conductive oxide layer prepared at this temperature tends to promote the formation of microcrystals in some areas, without excessive growth or lattice distortion, while simultaneously achieving improved carrier mobility and reduced film roughness. Furthermore, this step avoids the thermal desorption of hydroxyl groups caused by additional annealing. At this time, active hydrogen groups can be released by relying on the relatively high hydrogen content in the doped conductive oxide layer 320. These active hydrogen groups, together with the rare earth element doping components and the specific crystallinity of the doped conductive oxide layer 320, control the lattice arrangement, which promotes the formation of a large number of active sites in the lattice. Moreover, the active hydrogen groups react with oxygen atoms in the metal oxide lattice in a controllable manner to generate hydroxyl groups, thereby introducing discontinuous active regions rich in covalently bonded hydroxyl groups into the doped conductive oxide layer 320. This enhances the coverage and binding strength of the carrier transport layer molecules to the interface in the perovskite top cell, and finally constructs a large number of active anchoring points at the contact interface between the doped conductive oxide layer 320 and the top cell.

[0129] Furthermore, during the preparation of the doped conductive oxide layer 320, the physical vapor deposition temperature is 120℃~180℃.

[0130] In some examples, the preparation steps of the transparent conductive oxide layer 310 include: using a TCO target, performing physical vapor deposition under a mixed atmosphere of inert gas, oxygen, and hydrogen, and a deposition temperature ≤80°C. During the physical vapor deposition of the transparent conductive oxide layer, the sputtering power of the TCO target is 2kW~4kW. In this example, the volume fraction of hydrogen in the mixed atmosphere of inert gas, oxygen, and hydrogen is 0.2%~3%. More specifically, in this example, the volume fraction of inert gas in the mixed atmosphere is 95.5%~98%, the volume fraction of oxygen is 0.5%~2.5%, and the volume fraction of hydrogen is 0.2%~3%. In this example, the TCO target includes, but is not limited to, one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide. In this example, the deposition temperature includes, but is not limited to, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C. In this example gas mixture, the volume fraction of the inert gas includes, but is not limited to, 95.5%, 96%, 96.1%, 96.2%, 96.5%, 97%, 97.5%, or 98%. The volume fraction of oxygen includes, but is not limited to, 0.5%, 0.8%, 1%, 1.5%, 1.8%, 1.9%, 2%, 2.1%, or 2.5%. The volume fraction of hydrogen includes, but is not limited to, 0.2%, 0.5%, 1%, 1.5%, 1.8%, 2%, 2.5%, or 3%.

[0131] Understandably, the main differences between the preparation steps of the transparent conductive oxide layer 310 and the doped conductive oxide layer 320 lie in the presence or absence of rare earth element doping and the different deposition temperatures during the deposition process. Furthermore, the proportions of inert gas and oxygen gas differ during deposition. Through differentiated control of these process parameters, the two layers exhibit different properties in terms of crystallinity and surface active sites.

[0132] The different setup of the preparation steps of the transparent conductive oxide layer 310 and the doped conductive oxide layer 320 allows for precise matching of the interface requirements of the bottom cell side and the top cell side, enabling the two conductive oxide layers to form a gradient complementary structure in terms of crystallinity and surface active sites. This ensures low interfacial recombination and stress buffering on the bottom cell side, while achieving high film quality and carrier transport stability on the top cell side, ultimately improving the overall photoelectric conversion efficiency and long-term operational reliability of the tandem solar cell.

[0133] In some examples, after the step of forming the transparent conductive oxide layer 310 on the surface of the bottom cell and before the step of forming the doped conductive oxide layer 320, the method further includes:

[0134] Step a: Perform ultraviolet ozone pretreatment or plasma pretreatment on the transparent conductive oxide layer 310.

[0135] Optionally, the step of performing ultraviolet ozone pretreatment on the transparent conductive oxide layer 310 includes: irradiating the transparent conductive oxide layer 310 with ultraviolet light of 150W~200W, wherein the ozone concentration in the ultraviolet ozone pretreatment step is 500ppm~3000ppm. Further, the step of performing ultraviolet ozone pretreatment on the transparent conductive oxide layer 310 includes: irradiating the transparent conductive oxide layer 310 with ultraviolet light of 185nm and 254nm dual wavelengths, a power of 150W~200W, and an ozone concentration of 500ppm~3000ppm.

[0136] Optionally, the plasma pretreatment step of the transparent conductive oxide layer 310 includes: performing pretreatment under the conditions of a plasma generator power of 250W~1000W, a working gas pressure of 10Pa~20Pa, and a bias voltage of 50V~100V. Further, the plasma pretreatment step of the transparent conductive oxide layer 310 includes: using CDA or nitrogen plasma, a plasma generator power of 250W~1000W, a working gas pressure of 10Pa~20Pa, and a bias voltage of 50V~100V.

[0137] The surface of the transparent conductive oxide layer 310 is rich in hydroxyl groups existing in the form of covalent bonds and surface hydroxyl groups that are physically or chemically adsorbed. Among them, surface hydroxyl groups easily adsorb impurities such as small organic molecules, water, and dust. After UV ozone pretreatment or plasma pretreatment of the transparent conductive oxide layer 310, the surface adsorbed impurities can be efficiently removed and the proportion of covalent hydroxyl groups can be increased, thereby reducing the problem of increased carrier recombination probability caused by interface impurities. At the same time, combined with the crystal structure and active anchoring sites of the doped conductive oxide layer, it can alleviate the surface damage of the transparent conductive oxide layer 310 after UV ozone pretreatment or plasma pretreatment, thereby maintaining the carrier transport capability of the intermediate connection layer 30, and laying a stable interface foundation for the dense and orderly growth of subsequent carrier transport layers such as the hole transport layer 110.

[0138] In some of these examples, step S30, which involves forming a top cell 10 on the surface of the intermediate interconnect layer 30, includes: preparing a hole transport layer 110 on the surface of a conductive oxide layer 320 doped in the intermediate interconnect layer 30.

[0139] A perovskite layer 120 and an electron transport layer 130 are sequentially prepared on the surface of the hole transport layer 110 away from the doped conductive oxide layer 320.

[0140] The hole transport layer 110 comprises a self-assembled monolayer. The preparation method of the self-assembled monolayer includes: dissolving the self-assembled monomolecular material in a solvent to prepare a mixture; coating the mixture onto the surface of the doped conductive oxide layer 320 in the intermediate linking layer 30; and performing a solvent removal treatment to prepare the hole transport layer 110. Optionally, the coating method includes one or more of coating, spin coating, blade coating, and dip-coating. The self-assembled monomolecular material includes one or more of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

[0141] In some examples, step S30, which involves forming the top cell 10 on the surface of the intermediate connection layer 30, further includes:

[0142] A first TCO layer 140 is prepared on the side of the electron transport layer 130 opposite to the perovskite layer 120; a first electrode layer 150 is prepared on the side of the first TCO layer 140 opposite to the electron transport layer 130.

[0143] Furthermore, the preparation method of the first TCO layer 140 includes: selecting a TCO target material, using an argon flow rate of 100 sccm to 500 sccm, an oxygen flow rate of 5 sccm to 20 sccm, and a power of 1.5 kW to 3.5 kW. The selected TCO target material includes, but is not limited to, one or more of indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and indium gallium zinc oxide (IGZO).

[0144] The materials, thicknesses, etc. of each functional layer in the top battery 10 of the first aspect of this application are the same as those in the first aspect of this application, so they will not be repeated here.

[0145] A third aspect of this application provides a photovoltaic module, including a tandem solar cell 1 as exemplified by any of the examples in the first aspect of this application, or a tandem solar cell 1 prepared by any of the preparation methods in the second aspect of this application.

[0146] A fourth aspect of this application provides a power generation device, including a tandem solar cell 1 as described in any one of the first aspects of this application or including a tandem solar cell 1 prepared by any one of the preparation methods of the second aspect of this application.

[0147] A fifth aspect of this application provides an electrical device comprising a tandem solar cell 1 as described in any one of the first aspects of this application, or comprising a tandem solar cell 1 prepared by any one of the preparation methods of the second aspect of this application. As an example, the electrical device may be a lighting device, an energy storage device, etc. For instance, the electrical device may be a solar water heater, a solar street light, a solar photovoltaic generator, etc.

[0148] In order to objectively evaluate the technical effects of the embodiments of this application, this application will be described in detail by way of example through the following embodiments and comparative examples.

[0149] In the following examples and comparative examples, all raw materials were commercially available, and to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples had the same physical and chemical parameters or were prepared by the same processing method.

[0150] Example 1

[0151] Example 1 provides a tandem solar cell 1 and its preparation method, the preparation method being as follows:

[0152] (1) A bottom cell 20 is provided, the bottom cell 20 including an N-type silicon layer 240, a first intrinsic amorphous silicon layer 220, a silicon substrate 210, a second intrinsic amorphous silicon layer 230, a P-type silicon layer 250 and a second TCO layer 260 stacked sequentially.

[0153] The fabrication steps of the bottom cell 20 are as follows: a silicon substrate 210 (280 μm thick) is provided, the silicon substrate 210 having a first surface and a second surface arranged opposite to each other; the first surface and the second surface are texturized using a cleaning and texturing device; then a first intrinsic amorphous silicon layer 220 (1 nm thick) and a second intrinsic amorphous silicon layer 230 (1 nm thick) are formed on the first surface and the second surface, respectively; a 50 nm N-type microcrystalline silicon layer is fabricated on the side of the first intrinsic amorphous silicon layer 220 opposite to the first surface. A 50nm P-type microcrystalline silicon layer is prepared on the side of the second intrinsic amorphous silicon layer 230 away from the second surface as the P-type silicon layer 250. An 80nm ITO layer is deposited on the surface of the P-type silicon layer 250 away from the second intrinsic amorphous silicon layer 230 as the second TCO layer 260 using magnetron sputtering deposition. The parameters of the magnetron sputtering deposition are as follows: ITO target material is selected, argon flow rate is 320sccm, oxygen flow rate is 15sccm, and power is 2.4kW.

[0154] (2) Preparation of transparent conductive oxide layer 310

[0155] A transparent conductive oxide layer 310 is prepared on the surface of the N-type silicon layer 240 in the bottom cell 20 away from the first intrinsic amorphous silicon layer 220. The preparation steps of the transparent conductive oxide layer 310 are as follows: ITO target material is selected, the deposition temperature is 80℃, the power is 2.4kW, and the volume fraction of argon gas in the mixed gas is 96.1%, the volume fraction of hydrogen gas is 2%, and the volume fraction of oxygen gas is 1.9%, so as to prepare a 10nm transparent conductive oxide layer 310.

[0156] (3) Perform ultraviolet ozone pretreatment on the transparent conductive oxide layer 310.

[0157] The transparent conductive oxide layer 310 was irradiated with ultraviolet light (185nm and 254nm dual wavelengths) with a power of 180W, and the ozone concentration was 1000ppm in the ultraviolet ozone pretreatment step for 5 minutes.

[0158] (4) Preparation of doped conductive oxide layer 320

[0159] After ultraviolet ozone pretreatment, a doped conductive oxide layer 320 is prepared on the surface of the transparent conductive oxide layer 310 on the side opposite to the bottom cell 20. The doped conductive oxide layer 320 is a cerium hydride-doped indium oxide layer with a thickness of 5 nm. The preparation steps of the cerium hydride-doped indium oxide layer are as follows: a cerium-doped ITO target is selected, and the volume fractions of argon, hydrogen, and oxygen in the mixed gas are 92.34%, 2.66%, and 5%, respectively; the power is 3kW, the deposition temperature is 60℃, and the mass fraction of cerium in the cerium-doped ITO target is 3.2%.

[0160] (5) Preparation of hole transport layer 110

[0161] [2-(9H-carbazole-9-yl)ethyl]phosphonic acid 2PACz was dissolved in water to prepare a mixture; the mass fraction of 2PACz in the mixture was 0.5 mg / ml; the mixture was coated on the side of the doped conductive oxide layer 320 opposite to the transparent conductive oxide layer 310, and after drying, a hole transport layer 110 with a thickness of 15 nm was prepared.

[0162] (6) Preparation of perovskite layer 120, electron transport layer 130, and first TCO layer 140

[0163] Cs with a mole fraction of 1.6 mol / L 0.2 FA 0.8 Pb(I 0.8 Br 0.2 3. A perovskite precursor solution was coated on the surface of hole transport layer 110. After solvent removal, it was annealed at 150℃ for 20 min to prepare a perovskite layer 120 with a thickness of 700 nm. A 15 nm C60 layer was prepared on the surface of perovskite layer 120 as an electron transport layer 130 using thermal evaporation. A 50 nm thick ITO layer was prepared on the surface of electron transport layer 130 as the first TCO layer 140 using magnetron sputtering. The preparation parameters of the first TCO layer 140 were: ITO target material, argon flow rate of 320 sccm, oxygen flow rate of 15 sccm, and power of 2.4 kW.

[0164] (7) Fabrication of the first electrode layer 150 and the second electrode layer 270

[0165] Using a screen printing apparatus, a first electrode layer 150 with a thickness of 500 nm is prepared on the surface of the first TCO layer 140 away from the electron transport layer 130, and a second electrode layer 270 with a thickness of 800 nm is prepared on the surface of the second TCO layer 260 away from the P-type silicon layer 250.

[0166] Example 2

[0167] The preparation method of the tandem solar cell 1 in Example 2 is basically the same as that in Example 1. The main difference is that step (4) is different. Step (4) in Example 2 is as follows:

[0168] (4) Preparation of doped conductive oxide layer 320

[0169] After ultraviolet ozone pretreatment, a doped conductive oxide layer 320 is prepared on the side of the transparent conductive oxide layer 310 facing away from the bottom cell 20. The doped conductive oxide layer 320 is a cerium hydride-doped indium oxide layer with a thickness of 5 nm. The preparation steps of the cerium hydride-doped indium oxide layer are as follows: a cerium-doped ITO target is selected, with the volume fractions of argon, hydrogen, and oxygen being 92.34%, 2.66%, and 5%, respectively; the power is 3 kW, the deposition temperature is 180 °C, and the mass fraction of cerium in the cerium-doped ITO target is 3.2%.

[0170] Example 3

[0171] The preparation method of the tandem solar cell 1 in Example 3 is basically the same as that in Example 1. The main difference is that step (4) is different. Step (4) in Example 3 is as follows:

[0172] (4) Preparation of doped conductive oxide layer 320

[0173] After ultraviolet ozone pretreatment, a doped conductive oxide layer 320 is prepared on the side of the transparent conductive oxide layer 310 facing away from the bottom cell 20. The doped conductive oxide layer 320 is a cerium hydride-doped indium oxide layer with a thickness of 5 nm. The preparation steps of the cerium hydride-doped indium oxide layer are as follows: a cerium-doped IZO target is selected, with the volume fractions of argon, hydrogen, and oxygen being 92.34%, 2.66%, and 5%, respectively; the power is 3 kW, the deposition temperature is 180 °C, and the mass fraction of cerium in the cerium-doped IZO target is 3.2%.

[0174] Example 4

[0175] The preparation method of the tandem solar cell 1 in Example 4 is basically the same as that in Example 2. The main difference is that in step (4) of Example 4, the mass fraction of cerium in the cerium-doped ITO target is 2.0%.

[0176] Example 5

[0177] The preparation method of the tandem solar cell 1 in Example 5 is basically the same as that in Example 2. The main difference is that in step (4) of Example 5, the mass fraction of cerium in the cerium-doped ITO target is 4.5%.

[0178] Example 6

[0179] The fabrication method of the tandem solar cell 1 in Example 6 is basically the same as that in Example 1. The main difference is that in step (4) of Example 6, the doped conductive oxide layer 320 is a 5nm thick antimony hydride-doped indium oxide layer. The antimony hydride-doped indium oxide layer is prepared using an antimony-doped ITO target. The preparation steps are as follows: an antimony-doped ITO target is selected, and the volume fractions of argon, hydrogen, and oxygen in the mixed gas are 92.34%, 2.66%, and 5%, respectively; the power is 3kW, the deposition temperature is 180℃, and the mass fraction of cerium in the antimony-doped ITO target is 3.2%.

[0180] Example 7

[0181] The fabrication method of the tandem solar cell 1 in Example 7 is basically the same as that in Example 1. The main difference is that in step (4) of Example 7, the doped conductive oxide layer 320 is a yttrium-doped indium oxide layer with a thickness of 5 nm. The yttrium-doped indium oxide layer is fabricated using a yttrium-doped ITO target. The fabrication steps are as follows: a yttrium-doped ITO target is selected, and the volume fractions of argon, hydrogen, and oxygen in the mixed gas are 92.34%, 2.66%, and 5%, respectively; the power is 3kW, the deposition temperature is 180℃, and the mass fraction of cerium in the yttrium-doped ITO target is 3.2%.

[0182] Example 8

[0183] The preparation method of the tandem solar cell 1 in Example 8 is basically the same as that in Example 2. The main difference is that in step (4) of Example 8, the deposition temperature is 120°C.

[0184] Example 9

[0185] The preparation method of the tandem solar cell 1 in Example 9 is basically the same as that in Example 2. The main difference is that in step (4) of Example 9, the deposition temperature is 90°C.

[0186] Example 10

[0187] The preparation method of the tandem solar cell 1 in Example 10 is basically the same as that in Example 1, the main difference being that step (4) in Example 10 is:

[0188] (4) Preparation of doped conductive oxide layer

[0189] After ultraviolet ozone pretreatment, a doped conductive oxide layer is prepared on the surface of the transparent conductive oxide layer 310 on the side opposite to the bottom cell 20. The doped conductive oxide layer is a cerium-doped indium oxide layer with a thickness of 5 nm. The preparation steps of the cerium-doped indium oxide layer are as follows: a cerium-doped ITO target is selected, the argon-oxygen flow rate ratio is 95%:5%; the power is 3kW, the deposition temperature is 60℃, and the mass fraction of cerium in the cerium-doped ITO target is 3.2%.

[0190] Example 11

[0191] The preparation method of the tandem solar cell 1 in Example 11 is basically the same as that in Example 1, the main difference being that step (4) in Example 11 is:

[0192] (4) Preparation of doped conductive oxide layer

[0193] After ultraviolet ozone pretreatment, a doped conductive oxide layer is prepared on the surface of the transparent conductive oxide layer 310 on the side opposite to the bottom cell 20. The doped conductive oxide layer is a cerium-doped indium oxide layer with a thickness of 5 nm. The preparation steps of the cerium-doped indium oxide layer are as follows: a cerium-doped IZO target is selected, the argon-oxygen flow rate ratio is 95%:5%, the power is 3kW, the deposition temperature is 60℃, and the mass fraction of cerium in the cerium-doped indium oxide target is 3.2%.

[0194] Comparative Example 1

[0195] The preparation method of the tandem solar cell 1 in Comparative Example 1 is basically the same as that in Example 1, the main difference being that step (4) in Comparative Example 1 is:

[0196] (4) Preparation of doped conductive oxide layer 320

[0197] After ultraviolet ozone pretreatment, a hydrogenated conductive oxide layer is prepared on the surface of the transparent conductive oxide layer 310 on the side opposite to the bottom cell 20. The hydrogenated conductive oxide layer is a 5 nm thick indium hydrogen oxide layer. The preparation steps of the indium hydrogen oxide layer are as follows: a rare earth-doped ITO target is selected, and the volume fractions of argon, hydrogen, and oxygen are 92.34%, 2.66%, and 5%, respectively; the power is 3 kW, and the deposition temperature is 60 °C.

[0198] The photoelectric performance of the tandem solar cell 1 in the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0199] Table 1

[0200]

[0201] The carrier mobility and sheet resistance of the doped conductive oxide layer 320 in the examples and comparative examples were tested, and the corresponding test results are shown in Table 2.

[0202] Table 2

[0203]

[0204] As can be seen from Tables 1 and 2, Comparative Example 1 was not doped with rare earth elements, which resulted in the photoelectric performance of each comparative example being worse than that of Examples 1 to 11.

[0205] Examples 1, 2, 8, and 9 are basically the same, with the main difference being the different process temperatures in the physical vapor deposition (PVD) step for preparing the doped conductive oxide layer. Table 1 shows that examples 2 and 8, which prepare the doped conductive oxide layer at 120℃~180℃, are more conducive to improving the photoelectric performance of the solar cell.

[0206] Example 2 and Example 3 are basically the same, the main difference being that the target material in the doped conductive oxide layer is different. As can be seen from the comparison between the two, ITO is used as the target material in Example 2, and the solar cell produced in this case has better performance.

[0207] Examples 2, 4, and 5 are basically the same, with the main difference being the different doping ratios of rare earth elements. As can be seen from the comparison of the three, the rare earth element content is between 3% and 4.5%, which is more conducive to improving the photoelectric performance of solar cells.

[0208] Examples 2, 6, and 7 are essentially the same, the main difference being the type of rare earth element used for doping. A comparison of the three shows that the solar cells exhibit superior photoelectric performance when doped with cerium or antimony.

[0209] Furthermore, the XRD pattern of the doped conductive oxide layer obtained in Example 1 is shown below. Figure 2 As shown. The XRD pattern of the doped conductive oxide layer obtained in Example 2 of this application is shown below. Figure 3 As shown. By Figure 2 and Figure 3 As can be seen from the comparison, Figure 2 In this process, the temperature is relatively low, at which point... Figure 2 The wider peak shape, lower intensity, and greater baseline fluctuation indicate that its crystallinity is relatively poor, and it is closer to microcrystalline or partially amorphous state. Figure 3 The main peak is sharper and has higher intensity, which indicates that the increase in deposition temperature significantly improves the crystallinity and grain order of the doped conductive oxide layer.

[0210] Examples 10 and 11 did not undergo hydrogenation treatment on the doped conductive oxide layer. Compared with the doped conductive oxide layers prepared by hydrogenation treatment in Examples 1 to 9, the technical effects of Examples 10 and 11 were slightly inferior.

[0211] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0212] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A tandem solar cell, characterized in that, include: A top battery and a bottom battery, and an intermediate connecting layer disposed between the top battery and the bottom battery; The intermediate connection layer includes a transparent conductive oxide layer and a doped conductive oxide layer stacked together. The transparent conductive oxide layer is disposed near the bottom cell, and the doped conductive oxide layer is disposed near the top cell. The doped conductive oxide layer is doped with rare earth elements.

2. The tandem solar cell according to claim 1, characterized in that, The thickness of the doped conductive oxide layer is 1 nm to 10 nm; and / or, The sheet resistance of the doped conductive oxide layer is 3000 Ω / sq to 30000 Ω / sq; and / or, The carrier mobility of the doped conductive oxide layer is 20 cm⁻¹ 2 / (V·s)~35cm 2 / (V·s).

3. The tandem solar cell according to claim 1, characterized in that, The conductive oxide layer includes one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide; the rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium.

4. The tandem solar cell according to claim 3, characterized in that, The conductive oxide includes indium tin oxide; and / or, The rare earth elements include one or more of cerium and antimony.

5. The tandem solar cell according to claim 3, characterized in that, In the doped conductive oxide layer, the mass fraction of the rare earth element is 0.5% to 5%, with the sum of the mass fractions of the rare earth element and the conductive oxide being 100%.

6. The tandem solar cell according to claim 5, characterized in that, In the doped conductive oxide layer, the mass fraction of the rare earth element is 3% to 4.5%, with the sum of the mass fractions of the rare earth element and the conductive oxide being 100%.

7. The tandem solar cell according to claim 1, characterized in that, The doped conductive oxide layer is a hydrogenated doped conductive oxide layer.

8. The tandem solar cell according to claim 1, characterized in that, The material of the transparent conductive oxide layer includes one or more of indium oxide, indium tin oxide, indium zinc oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, and indium gallium zinc oxide; and / or, The thickness of the transparent conductive oxide layer is 1 nm to 10 nm.

9. The tandem solar cell according to any one of claims 1 to 8, characterized in that, The top cell includes a hole transport layer disposed on the surface of the doped conductive oxide layer, a perovskite layer and an electron transport layer disposed sequentially on the surface of the hole transport layer away from the doped conductive oxide layer.

10. The tandem solar cell according to claim 9, characterized in that, The hole transport layer comprises a self-assembled monolayer, which comprises a self-assembled monomolecule material, including one or more of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

11. The tandem solar cell according to any one of claims 1 to 8, characterized in that, The base battery includes one or more of HJT batteries, TOPCon batteries, and IBC batteries.

12. A method for fabricating a tandem solar cell, characterized in that, Includes the following steps: A bottom cell is provided, and a transparent conductive oxide layer and a doped conductive oxide layer are sequentially formed on the surface of the bottom cell to prepare an intermediate connection layer; A top battery is formed on the surface of the intermediate connecting layer; The doped conductive oxide layer is doped with rare earth elements.

13. The method for preparing a tandem solar cell according to claim 12, characterized in that, The method for preparing the doped conductive oxide layer includes: selecting a rare earth element-doped conductive oxide target and performing physical vapor deposition at a temperature of 55℃~200℃.

14. The method for preparing a tandem solar cell according to claim 13, characterized in that, The rare earth element-doped conductive oxide target includes one or more of indium tin oxide, indium zinc oxide, indium oxide, zinc oxide, and tin oxide; and the rare earth elements include one or more of erbium, cerium, antimony, yttrium, and gadolinium.

15. The method for preparing a tandem solar cell according to claim 14, characterized in that, The conductive oxide includes indium tin oxide; and / or, The rare earth elements include one or more of cerium and antimony.

16. The method for preparing a tandem solar cell according to claim 14, characterized in that, In the rare earth element-doped conductive oxide target, the mass fraction of the rare earth element is 0.5% to 5%.

17. The method for preparing a tandem solar cell according to claim 16, characterized in that, In the rare earth element-doped conductive oxide target, the mass fraction of the rare earth element is 3% to 4.5%.

18. The method for preparing a tandem solar cell according to any one of claims 13 to 17, characterized in that, When preparing the doped conductive oxide layer, physical vapor deposition is performed under a mixture of inert gas, oxygen, and hydrogen. When preparing the doped conductive oxide layer, the volume fraction of hydrogen in the mixture of the inert gas, the oxygen gas, and the hydrogen gas is 0.2% to 3%.

19. The method for preparing a tandem solar cell according to any one of claims 13 to 17, characterized in that, The sputtering power using the rare earth element-doped conductive oxide target is 2kW~4kW; and / or, During the preparation of the doped conductive oxide layer, the physical vapor deposition temperature is 120℃~200℃.

20. The method for preparing a tandem solar cell according to any one of claims 12 to 17, characterized in that, The method for preparing the transparent conductive oxide layer includes: selecting a TCO target material and performing physical vapor deposition under conditions of an inert gas, a mixture of oxygen and hydrogen, and a deposition temperature ≤80℃.

21. The method for preparing a tandem solar cell according to claim 20, characterized in that, When preparing the transparent conductive oxide layer, the sputtering power of the TCO target is 2kW~4kW; and / or, When preparing the transparent conductive oxide layer, the volume fraction of hydrogen in the mixture of the inert gas, the oxygen gas, and the hydrogen gas is 0.2% to 3%.

22. The method for preparing a tandem solar cell according to any one of claims 12 to 17, characterized in that, After the step of forming the transparent conductive oxide layer on the surface of the bottom cell and before the step of forming the doped conductive oxide layer, the method further includes: The transparent conductive oxide layer is pretreated with ultraviolet ozone or plasma. The step of performing ultraviolet ozone pretreatment on the transparent conductive oxide layer includes: irradiating the transparent conductive oxide layer with ultraviolet light of 150W~200W, and the ozone concentration in the ultraviolet ozone pretreatment step is 500ppm~3000ppm. The step of plasma pretreatment of the transparent conductive oxide layer includes: pretreatment under the conditions of plasma generator power of 250W~1000W, working gas pressure of 10Pa~20Pa, and bias voltage of 50V~100V.

23. The method for preparing a tandem solar cell according to any one of claims 12 to 17, characterized in that, The step of forming a top cell on the surface of the intermediate interconnect layer includes: A hole transport layer is prepared on the surface of the doped conductive oxide layer in the intermediate interconnect layer; A perovskite layer and an electron transport layer are sequentially prepared on the surface of the hole transport layer away from the doped conductive oxide layer.

24. The method for preparing a tandem solar cell according to claim 23, characterized in that, The hole transport layer includes a self-assembled monolayer, and the self-assembled monolayer includes a self-assembled monomolecule material. The method for preparing the self-assembled monolayer includes: dissolving the self-assembled monomolecule material in a solvent to prepare a mixture; coating the mixture onto the surface of the doped conductive oxide layer in the intermediate connecting layer, and then performing a solvent removal treatment to prepare the self-assembled monolayer; wherein the coating method includes one or more of coating, spin coating, blade coating, and dip-coating.

25. A photovoltaic module, characterized in that, It includes the tandem solar cell according to any one of claims 1 to 11 or the tandem solar cell prepared by any one of claims 12 to 24.

26. A power generation device, characterized in that, It includes the tandem solar cell according to any one of claims 1 to 11 or the tandem solar cell prepared by any one of claims 12 to 24.

27. An electrical appliance, characterized in that, It includes the tandem solar cell according to any one of claims 1 to 11 or the tandem solar cell prepared by any one of claims 12 to 24.

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