Perovskite / Silicon Heterojunction Two-Terminal Tandem Solar Cell without ITO Electrode and Its Preparation Method

Abstract

The present invention provides a perovskite / silicon heterojunction tandem solar cell without an ITO electrode and a preparation method thereof. The anti-reflection thin film, the first electrode, the perovskite solar cell, the silicon heterojunction solar cell and the second electrode are sequentially arranged in the present invention. The anti-reflection layer provided by the present invention can reduce light reflection and increase light absorption; the first electrode provided is a metal grid silver nanowire electrode. By using the consistency of the metal grid and the good transmittance of the silver nanowires, more light can be incident and transmitted through the electrode, increasing the light absorption rate of the device. Secondly, in the perovskite solar cell, a double electron transport layer and a double hole transport layer are provided to optimize the parasitic light absorption caused by the introduction of the interface layer, improving the stability of the device. In addition, an optical microcavity structure is adopted in the silicon heterojunction solar cell. Under this structure, the solar cell can obtain a higher conversion efficiency and perform more excellently in terms of optoelectronic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly relates to a perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode and a preparation method thereof. Background Art

[0002] With the increasing depletion of non-renewable energy sources such as coal, oil, and natural gas, renewable energy has become a focus of scientific research at home and abroad. As an important part of renewable clean energy, solar energy has gradually attracted people's attention. Currently, the photovoltaic industry using solar power generation has attracted much attention. The photovoltaic technology based on solar cells is recognized as one of the technologies most likely to solve the problems of the continuous growth of energy demand and environmental issues faced by mankind today. In photovoltaic power generation, crystalline silicon cells dominate the photovoltaic market due to their high conversion efficiency, good stability, and mature preparation process. However, the theoretical limit of the efficiency of crystalline silicon solar cells is about 29.4%. In order to break through this efficiency limit, the most effective solution is to use several absorption materials with different bandgaps to form a multi-junction solar cell. Perovskite solar cells are an ideal choice for the top cell adapted to silicon cells because of their high absorption coefficient, adjustable bandgap, low cost, etc., and are expected to achieve higher conversion efficiency.

[0003] There are two common structures for perovskite / silicon heterojunction stacked devices. One is the two-terminal tandem structure of perovskite and silicon heterojunction cells, and the other is the four-terminal structure in which two sub-cells work independently. The two-terminal stacked solar cell has become a research hotspot for perovskite and crystalline silicon stacked cells due to its simple preparation process. The latest research report points out that the Swiss Federal Institute of Technology in Lausanne and the Swiss Center for Electronics and Microtechnology jointly created a new world record for the conversion rate of perovskite / silicon tandem solar cells of 31.3%.

[0004] Currently, in two-terminal stacked solar cells, the key problem lies in the current matching of the top and bottom cells, which poses more stringent requirements for the bandgaps of the top and bottom cells. Reasonably matching the bandgaps and distributing the spectrum are the prerequisites for achieving high conversion efficiency. The main parameters of perovskite / silicon heterojunction solar cells largely depend on the light transmittance of the transparent electrode of the perovskite solar cell. Currently, the most widely used transparent electrode materials are indium tin oxide (ITO), indium zinc oxide (IZO), etc. Among them, ITO is an element with toxicity, low conductivity, and high cost, and it also has a certain impact on the optical loss of the device. In addition, the main reason for parasitic absorption is the absorption of light by the transparent conductive layer and the interface layer. Improving the intermediate electrode and reducing the film thickness of the interface layer are also crucial in optical optimization. Therefore, it is particularly important to develop a new transparent electrode to replace ITO and enhance the light trapping in the device caused by the intermediate electrode, so as to obtain a higher conversion efficiency than conventional devices. Summary of the Invention

[0005] The object of the present invention is to overcome the above technical problems and provide a metal grid silver nanowire electrode to replace the ITO electrode. By utilizing the consistency of the metal grid and the good transmittance of silver nanowires, the conductivity of the electrode is made more excellent, achieving a balance of good optoelectronic comprehensive performance.

[0006] In order to overcome the problem of high parasitic light absorption in the interface layer of existing perovskite / silicon heterojunction tandem solar cells, the present invention provides a perovskite solar cell with a double electron transport layer and a double hole transport layer, improving the optical performance of the overall device and enhancing the stability of the device, thereby enabling a higher conversion efficiency to be obtained.

[0007] In order to achieve a higher conversion efficiency in perovskite / silicon heterojunction tandem solar cells, the present invention also provides a device structure of a silicon heterojunction solar cell including a microcavity structure. The cell with the microcavity structure can significantly increase the absorption efficiency of the incident light by the cell, achieve a higher conversion efficiency, and improve the comprehensive optoelectronic performance of the perovskite / silicon heterojunction solar cell.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A perovskite / silicon heterojunction tandem solar cell without an ITO electrode, with a perovskite cell having a wide bandgap (1.68 eV) as the top cell and a silicon heterojunction cell having a narrow bandgap (1.12 eV) as the bottom cell. The structure of this tandem cell is mainly reflected in: 1) A silicon heterojunction solar cell including a microcavity structure, where the microcavity structure is formed by introducing an ultrathin metal silver thin film layer as the top electrode and a dense metal silver thin film layer as the bottom electrode in the silicon heterojunction solar cell to jointly form an optical microcavity; 2) Adopting a double electron transport layer and a double hole transport layer in the perovskite solar cell to optimize the parasitic light absorption caused by the introduction of the interface layer, ensuring the high working efficiency of the device; 3) Using a metal grid silver nanowire electrode as the first electrode to replace the ITO electrode, which can allow more light to enter and pass through the electrode, increasing the light absorption rate of the device; 4) Adding an antireflection thin film on the surface of the first electrode to reduce the light reflection on the surface of the device and increase the light absorption.

[0010] The perovskite / silicon heterojunction tandem solar cell without an ITO electrode includes, from top to bottom in sequence, an antireflection thin film, a first electrode, a perovskite solar cell, a silicon heterojunction solar cell, and a second electrode;

[0011] The perovskite solar cell includes, from top to bottom in sequence, a first hole transport layer, a second hole transport layer, a perovskite absorption layer, a first electron transport layer, and a second electron transport layer;

[0012] The described silicon heterojunction solar cell includes, from top to bottom, a first transparent conductive thin film forming a microcavity structure, a P-type amorphous silicon layer, a first intrinsic amorphous silicon layer, a silicon wafer substrate, a second intrinsic amorphous silicon layer, an N-type amorphous silicon layer, and a second electrode forming a microcavity structure.

[0013] Preferably, the antireflection thin film material is one of LiF, MgF2, PDMS, or LM foil. Among them, in series-connected solar cells at both ends, reflection loss accounts for a large part of the optical loss, and setting an antireflection layer can reduce light reflection and increase light absorption.

[0014] The first electrode is a metal grid silver nanowire electrode to replace the conventional ITO electrode. Utilizing the uniformity of the metal grid and the good transmittance of silver nanowires, the conductivity of the electrode is more excellent, allowing more light to enter and pass through the electrode, increasing the light absorption rate of the device.

[0015] Preferably, the materials of the first hole transport layer and the second hole transport layer of the perovskite solar cell are one of the organic PTAA, CuI, Spiro-OMeTAD, or Spiro-TTB or the inorganic materials NiO, MnS, or MoO3; a CuI hole transport layer is inserted between the perovskite absorption layer and the Spiro-OMeTAD hole transport layer by solution spin coating; the CuI layer deposited on the perovskite film covers the surface defects of the perovskite and also reduces the roughness caused by the Spiro-OMeTAD layer. Using a double hole transport layer improves the stability of the device and also optimizes the problem of relatively high parasitic light absorption caused by the introduction of the Spiro-OMeTAD layer.

[0016] Preferably, the materials of the first electron transport layer and the second electron transport layer of the perovskite solar cell are one of the organic PCBM, C 60 or BCP or the inorganic materials SnO2, TiO2, or SrTiO3. Among them, the SnO2 electron transport layer prepared by the low-temperature solution method is spin-coated on the perovskite absorption layer, and the ultrathin SrTiO3 electron transport layer is covered on the SnO2 layer; by changing the thickness of the SrTiO3 layer, the charge collection efficiency of the device can be optimized; using a double-layer composite electron transport layer optimizes and improves the device in terms of surface appearance, energy level matching, and electrochemistry, ensuring the high working efficiency of the device and obtaining a short-circuit current density higher than that of conventional devices.

[0017] Preferably, the perovskite absorption layer is a wide-bandgap organic-inorganic hybrid perovskite material or an all-inorganic perovskite material.

[0018] Preferably, the perovskite absorption layer is prepared by a solution method of two-step sequential deposition or one-step anti-solvent deposition.

[0019] Preferably, the silicon heterojunction solar cell is a planar silicon cell with a narrow bandgap, and the silicon cell is an N-type silicon wafer, a P-type silicon wafer, or a CZ-type silicon wafer.

[0020] Preferably, the first transparent conductive thin film of the microcavity structure adopts a microcavity structure with a MoO3 / Ag / MoO3 transparent electrode; the second electrode constituting the microcavity structure is a dense metal silver thin film layer; the thickness of the dense metal silver thin film is 50 - 200 nm; the thickness of the silver thin film layer in the first transparent conductive thin film is 5 - 15 nm.

[0021] The silicon heterojunction solar cell adopts a microcavity structure with a MoO3 / Ag / MoO3 transparent electrode. The microcavity structure introduces an ultra-thin metal silver thin film layer as the top electrode and a dense metal silver thin film layer as the bottom electrode in the silicon heterojunction solar cell to jointly form an optical microcavity. In this structure, the ultra-thin metal silver thin film does not affect the incidence of incident light, while the dense metal silver thin film reflects most of the visible light, which can greatly improve the light absorption efficiency of the device for sunlight, thus improving the conversion efficiency of the solar cell. Among them, the ultra-thin metal silver thin film and MoO3 with better antireflection effect form a MoO3 / Ag / MoO3 three-layer structure. The thickness of the ultra-thin silver thin film layer is 5 - 15 nm, and the thickness of the dense metal silver thin film is 50 - 200 nm.

[0022] A preparation method of a perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode, and the preparation method specifically includes the following steps:

[0023] S1. Prepare a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the upper and lower surfaces of the silicon wafer substrate respectively, and the first surface and the second surface are opposite;

[0024] S2. Fabricate a P-type amorphous silicon layer on the first intrinsic amorphous silicon layer, and fabricate an N-type amorphous silicon layer on the second intrinsic amorphous silicon layer;

[0025] S3. Fabricate an intermediate connection layer of an optical microcavity composed of an ultra-thin metal silver thin film and MoO3 with strong antireflection effect on the P-type amorphous silicon layer, and fabricate the second electrode of the optical microcavity on the N-type amorphous silicon layer;

[0026] S4. Fabricate a second electron transport layer on the intermediate connection layer; fabricate a first electron transport layer on the second electron transport layer;

[0027] S5. Fabricate and form a perovskite light absorption layer on the first electron transport layer;

[0028] S6. Fabricate and form a second hole transport layer on the perovskite light absorption layer; fabricate and form a first hole transport layer on the second hole transport layer;

[0029] S7. Fabricate and form a first electrode of metal grid silver nanowires on the first hole transport layer; fabricate and form an antireflection film on the first electrode.

[0030] A preparation method of a perovskite / silicon heterojunction tandem solar cell without an ITO electrode, which specifically includes the following steps:

[0031] S1. Use plasma enhanced chemical vapor deposition method to fabricate a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the first surface and the second surface of a silicon wafer substrate respectively. The first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are opposite to each other, and the thicknesses of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are 5 - 10 nm;

[0032] S2. Use plasma enhanced chemical vapor deposition method to deposit a P-type amorphous silicon layer with a thickness of 5 - 10 nm on the first intrinsic amorphous silicon layer, and deposit an N-type amorphous silicon layer with a thickness of 5 - 10 nm on the second intrinsic amorphous silicon layer;

[0033] S3. Use vacuum distillation method to prepare an ultra-thin silver film with a thickness of 5 - 15 nm and a bilayer MoO3 with a thickness of 20 - 60 nm on the P-type amorphous silicon layer; use physical vapor deposition method to deposit a dense metal silver film with a thickness of 50 - 200 nm on the N-type amorphous silicon as the second electrode;

[0034] S4. Use low-power magnetron sputtering method to prepare a 100-nm-thick metal grid silver nanowire as the first electrode; use thermal evaporation method to prepare LiF as the antireflection film on the first electrode;

[0035] S5. Use two-step sequential deposition method to prepare a perovskite absorption layer; spin-coat Spiro-OMeTAD on the perovskite absorption layer, and insert a CuI hole transport layer between the perovskite absorption layer and the Spiro-OMeTAD hole transport layer by solution spin-coating method to form a double hole transport layer;

[0036] S6. Spin-coat SnO2 as an electron transport layer on the back surface of the perovskite absorption layer, and prepare a SrTiO3 electron transport layer by spin-coating method on the SnO2 to form a double electron transport layer.

[0037] The present invention has the following beneficial effects:

[0038] The first electrode provided by the present invention uses a metal mesh silver nanowire electrode to replace the conventional ITO electrode. Due to the good electrical conductivity and good transmittance of the silver nanowires themselves, more light can be incident on the transparent electrode, which is beneficial to improving the efficiency of the battery; and a layer of antireflection film is added on the surface of the first electrode to reduce the light reflection on the surface of the device and increase the light absorption. Secondly, in the perovskite solar cell, a double electron transport layer and a double hole transport layer are used to optimize the parasitic light absorption caused by the introduction of the interface layer, greatly improving the light absorption of the device and ensuring the high working efficiency of the device. In addition, a silicon heterojunction solar cell including a microcavity structure is provided in the bottom cell. In this structure, a transparent metal silver thin film layer and an opaque dense metal silver thin film layer are introduced together as an optical microcavity, so that the sunlight incident on the bottom cell can be fully absorbed by the silicon heterojunction solar cell, which can greatly increase the light absorption efficiency of the overall device for the incident light, and thus improve the photoelectric conversion efficiency of the overall device; compared with the perovskite / silicon heterojunction tandem solar cell with a traditional structure, the perovskite / silicon heterojunction tandem solar cell with an optical microcavity structure shows more excellent performance in terms of photoelectric conversion performance, especially in terms of output current. Brief Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of a perovskite / silicon heterojunction stacked solar cell with a microcavity structure according to the present invention. Detailed Embodiments

[0040] The technical solutions of the invention will be further specifically described below through specific embodiments in conjunction with the drawings.

[0041] In the present invention, unless otherwise specified, all descriptions of the implementation schemes in combination with the embodiments are only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. Without special declaration, they are all conventional methods in the art.

[0042] The perovskite / silicon heterojunction tandem solar cell with a microcavity structure provided by the present invention. In the prior art, the transparent electrode of the perovskite solar cell in the tandem perovskite solar cell generally uses an ITO electrode or other transparent oxide materials, which has problems such as brittleness, low conductivity, and high cost, restricting the development of the perovskite / silicon heterojunction tandem solar cell. Therefore, a metal grid silver nanowire is used as the first electrode on the front side of the top layer of the tandem perovskite solar cell, which can effectively reduce the manufacturing cost of the battery and improve the conversion efficiency of the battery. Secondly, considering the parasitic absorption problem caused by the light absorption of the interface layer in the top perovskite solar cell, a double electron transport layer and a double hole transport layer are provided in the perovskite solar cell to suppress the optical loss in the device and improve the short-circuit current density of the overall device. In addition, an optical microcavity that can improve the light collection efficiency of the silicon heterojunction solar cell is added inside the silicon heterojunction solar cell, enabling the bottom cell to fully utilize and absorb sunlight, and enhancing the overall photoelectric conversion efficiency of the battery.

[0043] The perovskite / silicon heterojunction tandem solar cell with a microcavity structure described in the present invention, and the specific tandem cell structure is as Figure 1 shown. The basic structure of the perovskite solar cell is: an antireflection thin film LiF, a transparent conductive thin film metal grid silver nanowire, a hole transport layer Spiro-OMeTAD and CuI, a perovskite absorption layer Perovskite, an electron transport layer SnO2 and SrTiO3. The basic structure of the silicon heterojunction solar cell including a microcavity structure is: a microcavity structure layer composed of a MoO3 / Ag / MoO3 transparent electrode, a hole transport layer p-a-Si:H, a passivation layer i-a-Si:H, a silicon absorption layer n-c-Si, a passivation layer i-a-Si:H, an electron transport layer n-a-Si:H, and a dense metal silver thin film.

[0044] The perovskite / silicon heterojunction tandem solar cell with a microcavity structure in this embodiment is prepared by the following method:

[0045] In the top perovskite solar cell, the perovskite absorption layer is prepared by directly spin-coating a precursor solution. During the preparation process, an antisolvent chlorobenzene is added dropwise to extract the organic solvent to rapidly crystallize the perovskite thin film. The precursor solution is composed of methylammonium iodide (MAI) and lead iodide (PbI2) dissolved in a mixed solvent at a molar ratio of 1:1. The film deposition is prepared by spin-coating. The mixed solvent is a mixed solvent of DMSO and DMF, and the volume ratio of DMSO and DMF is 1:4. Then, heating and stirring are carried out at a stirring temperature of 75 °C for a stirring time of 1 h to obtain a clear MAPbI3 precursor solution.

[0046] Spiro-OMeTAD is spin-coated on the perovskite absorption layer, and a CuI hole transport layer is inserted between the perovskite absorption layer and the Spiro-OMeTAD hole transport layer by solution spin-coating method to form a double hole transport layer.

[0047] A 100-nm-thick metal grid silver nanowire is prepared on the buffer layer by low-power magnetron sputtering. Compared with the transparent electrode formed by transparent conductive oxide, the metal grid silver nanowire has good ductility, low resistivity and high light transmittance, which is beneficial to enhancing the current collection effect and increasing the effective current.

[0048] A 100-nm-thick LiF is prepared on the metal grid silver nanowire by thermal evaporation as an antireflection film.

[0049] SnO2 is spin-coated on the rear surface of the perovskite absorption layer as an electron transport layer, and a SrTiO3 electron transport layer prepared by spin-coating method is formed on the SnO2 to form a double electron transport layer.

[0050] In a silicon heterojunction solar cell with a microcavity structure at the bottom, the N-type silicon wafer is cleaned by the RCA standard cleaning method, and then the substrate is placed in an RF-PEVCD system with a high vacuum degree. A first intrinsic amorphous silicon layer is formed on the first surface of the silicon wafer substrate, and a second intrinsic amorphous silicon layer is formed on the second surface.

[0051] A 10-nm-thick P-type amorphous silicon layer is deposited on the first intrinsic amorphous silicon layer by plasma-enhanced chemical vapor deposition method, and a 10-nm-thick N-type amorphous silicon layer is deposited on the second intrinsic amorphous silicon layer by plasma-enhanced chemical vapor deposition method.

[0052] A silver thin film layer is prepared on the P-type amorphous silicon layer by vacuum evaporation, where the thickness of the ultra-thin silver film is 8 nm, and it forms a metal electrode together with MoO with a high dielectric constant X and serves as the connection layer between the perovskite solar cell and the silicon heterojunction solar cell. The silver thin film layer has good light transmission performance and the reflection of light is diffuse reflection.

[0053] A dense metal silver electrode is used as the back electrode of the silicon heterojunction cell by electron beam thermal evaporation on the N-type amorphous silicon layer, where the thickness of the dense metal silver electrode is 150 nm. It forms a microcavity structure together with the ultra-thin silver film, and the dense metal silver thin film layer can also serve as a conductive electrode layer. The dense metal silver thin film has poor light transmission performance and specular reflection, but excellent conductivity, which can fully absorb sunlight and improve the overall photoelectric conversion efficiency of the cell.

[0054] In summary, a perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode and a preparation method thereof according to an embodiment of the present invention. The top front electrode of the stacked perovskite solar cell uses a metal grid silver nanowire electrode. Compared with an ITO electrode or other transparent conductive oxide electrodes, the metal grid silver nanowire electrode has the advantages of good ductility, good conductivity, high light transmittance, and low cost, which is beneficial to improving the overall conversion efficiency of the battery. A layer of antireflection film is added on the surface of the first electrode, which can effectively reduce light reflection and increase light absorption. Secondly, in the perovskite solar cell, a double electron transport layer and a double hole transport layer are used to optimize the parasitic light absorption caused by the introduction of the interface layer, so that the stability of the device is improved. In addition, a silicon heterojunction solar cell including a microcavity structure is also provided. The optical microcavity configuration is an optical strategy that can enhance light trapping in the device caused by the planar electrode. This structure is organically combined with the classical silicon heterojunction solar cell, increasing the collection efficiency of incident light without affecting other performances of the battery and improving the photoelectric conversion efficiency of the battery. Therefore, the perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode has good development prospects.

[0055] As described above, the above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. For those of ordinary skill in the art, the content of this specification can be easily modified and replaced. Moreover, without departing from the protection scope of the content of this specification, the defined general principles or structures can be applied to other variants and modifications. Therefore, the content of this specification is not limited to the examples and designs described herein, but is consistent with the broadest scope that conforms to the principles, structures, and novel features disclosed herein.

Claims

1. A perovskite / silicon heterojunction tandem solar cell without an ITO electrode, characterized in that: The perovskite / silicon heterojunction tandem solar cell without an ITO electrode includes an antireflection film, a first electrode, a perovskite solar cell, a silicon heterojunction solar cell, and a second electrode, which are sequentially arranged from top to bottom; The first electrode is a metal grid silver nanowire electrode to replace the conventional ITO electrode; The perovskite solar cell includes a first hole transport layer, a second hole transport layer, a perovskite absorption layer, a first electron transport layer, and a second electron transport layer, which are sequentially arranged from top to bottom; The silicon heterojunction solar cell includes a first transparent conductive film forming a microcavity structure, a P-type amorphous silicon layer, a first intrinsic amorphous silicon layer, a silicon wafer substrate, a second intrinsic amorphous silicon layer, an N-type amorphous silicon layer, and a second electrode forming a microcavity structure, which are sequentially arranged from top to bottom; The first transparent conductive film of the microcavity structure adopts a microcavity structure with a MoO3 / Ag / MoO3 transparent electrode, and the thickness of the silver thin film layer is 5-15 nm; the second electrode is a dense metal silver thin film layer with a thickness of 50-200 nm.

2. The perovskite / silicon heterojunction tandem solar cell without an ITO electrode according to claim 1, wherein: The material of the antireflection film is one of LiF, MgF2, PDMS, or LM foil.

3. The perovskite / silicon heterojunction tandem solar cell without an ITO electrode according to claim 1, wherein: The materials of the first hole transport layer and the second hole transport layer of the perovskite solar cell are one of organic PTAA, CuI, Spiro-OMeTAD, or Spiro-TTB, or inorganic materials NiO, MnS, or MoO3.

4. The perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 1, characterized in that: The materials of the first electron transport layer and the second electron transport layer of the perovskite solar cell are organic PCBM, C 60 or BCP, or one of inorganic materials SnO2, TiO2 or SrTiO3.

5. The perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 1, characterized in that: The perovskite absorption layer is a wide-bandgap organic-inorganic hybrid perovskite material or an all-inorganic perovskite material.

6. The perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 1, characterized in that: The perovskite absorption layer is prepared by a solution method of two-step sequential deposition or one-step antisolvent deposition.

7. The perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 1, characterized in that: The silicon heterojunction solar cell is a narrow-bandgap planar silicon cell, and the silicon cell is an N-type silicon wafer, a P-type silicon wafer, or a CZ-type silicon wafer.

8. The preparation method of the perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 1, characterized in that: The preparation method specifically includes the following steps: S1. Prepare a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the upper and lower surfaces of the silicon wafer substrate respectively, and the upper and lower surfaces of the silicon wafer substrate are opposite; S2. Fabricate a P-type amorphous silicon layer on the first intrinsic amorphous silicon layer and fabricate an N-type amorphous silicon layer on the second intrinsic amorphous silicon layer; S3. Fabricate an intermediate connection layer of an optical microcavity with a three-layer structure of MoO3 / Ag / MoO3 by making an ultrathin metal silver thin film and MoO3 with strong antireflection effect on the P-type amorphous silicon layer, and fabricate the second electrode of the optical microcavity on the N-type amorphous silicon layer; S4. Fabricate a second electron transport layer on the intermediate connection layer; fabricate a first electron transport layer on the second electron transport layer; S5. Fabricate a perovskite light absorption layer on the first electron transport layer; S6. Fabricate a second hole transport layer on the perovskite light absorption layer; fabricate a first hole transport layer on the second hole transport layer; S7. Fabricate a metal grid silver nanowire first electrode on the first hole transport layer; fabricate an antireflection film on the first electrode.

9. The method for preparing a perovskite / silicon heterojunction two-terminal tandem solar cell without an ITO electrode according to claim 8, wherein: The preparation method specifically includes the following steps: S1. The first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are fabricated on the first surface and the second surface of the silicon wafer substrate respectively by plasma enhanced chemical vapor deposition. The first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are opposite to each other, and the thickness of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer is 5 - 10 nm; S2. A P-type amorphous silicon layer with a thickness of 5 - 10 nm is deposited on the first intrinsic amorphous silicon layer by plasma enhanced chemical vapor deposition, and an N-type amorphous silicon layer with a thickness of 5 - 10 nm is deposited on the second intrinsic amorphous silicon layer; S3. An ultra-thin silver film with a thickness of 5 - 15 nm and a bilayer MoO3 with a thickness of 20 - 60 nm are prepared on the P-type amorphous silicon layer by vacuum distillation; A dense metallic silver film with a thickness of 50 - 200 nm is deposited on the N-type amorphous silicon by physical vapor deposition as the second electrode; S4. A 100-nm-thick metal grid silver nanowire is prepared as the first electrode by low-power magnetron sputtering; LiF is prepared as an antireflection film on the first electrode by thermal evaporation; S5. A perovskite absorption layer is prepared by a two-step sequential deposition method; Spiro-OMeTAD is spin-coated on the perovskite absorption layer, and a CuI hole transport layer is inserted between the perovskite absorption layer and the Spiro-OMeTAD hole transport layer by solution spin-coating to form a double hole transport layer; S6. SnO2 is spin-coated as an electron transport layer on the rear surface of the perovskite absorption layer, and an SrTiO3 electron transport layer prepared by spin-coating is formed on the SnO2 to form a double electron transport layer.

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