Electron transport layer, perovskite silicon laminated solar cell and preparation method

Abstract

The invention discloses an electron transport layer, a perovskite silicon laminated solar cell and a preparation method, and belongs to the technical field of perovskite photovoltaics. The electron transport layer is used for the perovskite silicon laminated solar cell, the perovskite silicon laminated solar cell comprises a silicon bottom cell, and the electron transport layer comprises a lithium fluoride layer, a fullerene layer, a modification layer and a buffer layer which are sequentially laminated along the direction gradually away from the light receiving surface of the silicon bottom cell; and the material of the modification layer is polyethylene terephthalate, polymethyl methacrylate, polyoxyethylene, polyethyleneimine or branched polyethyleneimine. Based on the arrangement of the modification layer, the crystallinity of the buffer layer and the carrier transmission performance of the buffer layer are improved, water, oxygen and ion transmission channels in the buffer layer are reduced, and the fullerene layer and a buffer layer precursor are isolated; the problems that in the prior art, a low-temperature atomic layer deposition buffer layer is adopted, so that a perovskite light absorption layer is damaged, and the stability of the perovskite silicon laminated solar cell is affected are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite photovoltaic technology, and particularly relates to an electron transport layer, a perovskite / silicon tandem solar cell, and a preparation method thereof. Background Art

[0002] The electron transport layer is one of the important functional layers of the tandem perovskite / silicon solar cell, mainly including a lithium fluoride layer, a fullerene layer, and a buffer layer stacked in sequence along the direction gradually away from the silicon bottom cell. Among them, the lithium fluoride layer, as an interface passivation layer, is in direct contact with the perovskite light-absorbing layer; the fullerene layer has the functions of energy level matching and selective carrier transport; the buffer layer can not only avoid the damage of the magnetron sputtering process to the fullerene layer when depositing the conductive electrode, but also extend the life of the cell in environments such as humidity and heat.

[0003] Currently, in order to protect the perovskite light-absorbing layer with poor temperature tolerance, the buffer layer is usually prepared by a low-temperature atomic layer deposition (ALD) process.

[0004] However, on the one hand, due to the lack of nucleophilic functional groups such as hydroxyl, carbonyl, and amino groups, during the low-temperature atomic layer deposition process, the precursor of the buffer layer cannot be chemically adsorbed on the surface of the fullerene layer, resulting in the precursor of the buffer layer diffusing into the fullerene layer and forming island-like growth in its surface layer, so that a clear interface cannot be formed between the fullerene layer and the buffer layer. The buffer layer with poor crystallinity has poor carrier transport performance, and there are a large number of water oxygen and ion transport channels in the buffer layer, which will accelerate the decomposition of the perovskite light-absorbing layer and damage the perovskite light-absorbing layer; on the other hand, due to the poor compactness of the buffer layer, the buffer functionality is poor, which in turn affects the stability of the perovskite / silicon tandem solar cell; on the other hand, due to the low nucleation rate on the surface of the fullerene layer, the number of cycles of low-temperature atomic layer deposition is greatly increased, resulting in material waste and process time extension. At the same time, during the cycle, the perovskite light-absorbing layer is easily structurally damaged by repeated heating. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide an electron transport layer, a perovskite / silicon tandem solar cell, and a preparation method thereof, which solve the problems of damage to the perovskite light-absorbing layer and influence on the stability of the perovskite / silicon tandem solar cell caused by using low-temperature atomic layer deposition of the buffer layer in the prior art.

[0006] The object of the present invention is mainly achieved by the following technical solutions:

[0007] In a first aspect, the present invention provides an electron transport layer for a perovskite-silicon tandem solar cell. The perovskite-silicon tandem solar cell includes a silicon bottom cell. The electron transport layer includes a lithium fluoride layer, a fullerene layer, a modification layer, and a buffer layer that are sequentially stacked along the direction gradually away from the light-receiving surface of the silicon bottom cell. The material of the modification layer is polyethylene terephthalate, polymethyl methacrylate, polyethylene oxide, polyimide, or branched polyethyleneimine.

[0008] Further, the thickness of the modification layer is 1 to 5 nm.

[0009] Further, the thickness of the lithium fluoride layer is 1 to 3 nm; and / or, the thickness of the fullerene layer is 5 to 30 nm; and / or, the thickness of the buffer layer is 13 to 62 nm.

[0010] Further, the material of the fullerene layer is at least one or two or more of fullerene or fullerene derivatives; and / or, the material of the buffer layer is one of titanium dioxide, tin oxide, zinc oxide, or niobium oxide.

[0011] In a second aspect, the present invention provides a perovskite-silicon tandem solar cell, including a silicon bottom cell, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a front recombination layer, and a positive electrode that are sequentially stacked on the light-receiving surface of the silicon bottom cell, and a back electrode stacked on the backlight surface of the silicon bottom cell. The electron transport layer is the electron transport layer provided in the first aspect.

[0012] In a third aspect, the present invention provides a method for manufacturing a perovskite-silicon tandem solar cell, which is characterized in that it is used for manufacturing the perovskite-silicon tandem solar cell provided in the second aspect. The manufacturing method includes the following steps:

[0013] Step a: Provide a silicon bottom cell;

[0014] Step b: Sequentially form a hole transport layer, a perovskite light-absorbing layer, a lithium fluoride layer, a fullerene layer, a modification layer, a buffer layer, a front recombination layer, and a positive electrode on the light-receiving surface of the silicon bottom cell, and form a back electrode on the backlight surface of the silicon bottom cell.

[0015] Further, the formation method of the lithium fluoride layer adopts vacuum thermal evaporation deposition, and the evaporation rate of lithium fluoride is 0.01 to 0.02 nm / s.

[0016] Further, the formation method of the fullerene layer adopts vacuum thermal evaporation deposition, and the evaporation rate of fullerene is 0.02 to 0.03 nm / s.

[0017] Further, the method for forming the modification layer is spin coating; in a nitrogen or inert gas protective atmosphere, a mixed solution of a modification layer material and an organic solvent is spin coated on the fullerene layer, and the modification layer is formed after heating; the concentration of the modification layer material in the mixed solution is 0.05 - 0.1 mg / mL, the spin coating acceleration is 3000 - 4000 rad / s, the spin coating rate is 6000 - 8000 rad / min, the spin coating time is 25 - 35 s, the heating temperature is 90 - 100 °C, and the heating time is 1 - 5 min.

[0018] Further, the method for forming the buffer layer is low-temperature atomic layer deposition, the heating temperature is 90 - 100 °C, in each cycle, the feeding time of the buffer layer precursor is 0.1 - 0.2 seconds, the evacuation time is 3 - 6 seconds, the feeding time of water is 0.02 - 0.04 seconds, and the evacuation time is 4 - 6 seconds.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] A) For the electron transport layer provided by the present invention, on the basis of ensuring that the electron transport layer has energy levels matching the perovskite light-absorbing layer and the function of selectively transporting carriers, a modification layer is added between the fullerene layer and the buffer layer. The modification layer is formed by a polymer having nucleophilic functional groups such as hydroxyl, carbonyl, and amino groups. During the subsequent low-temperature atomic layer deposition process of the buffer layer, the buffer layer precursor can form chemisorption on the surface of the modification layer, which is equivalent to increasing the crystal nuclei for the crystallization of the buffer layer precursor, facilitating the uniform attachment and nucleation of the low-temperature atomic layer deposition buffer layer precursor on the surface of the modification layer. This can not only improve the crystallinity of the buffer layer and the carrier transport performance of the buffer layer, reduce the water oxygen and ion transport channels in the buffer layer, improve the photoelectric conversion efficiency and damp heat stability of the perovskite silicon tandem solar cell, but also reduce the number of cycles of low-temperature atomic layer deposition, reduce the usage amount of the buffer layer precursor, improve the formation efficiency of the buffer layer, and ensure the stability of the perovskite light-absorbing layer.

[0021] B) For the electron transport layer provided by the present invention, the setting of the modification layer isolates the fullerene layer and the buffer layer precursor, and the buffer layer precursor cannot diffuse into the fullerene layer, thereby ensuring a clear interface between the fullerene layer and the modification layer and improving the photoelectric conversion efficiency of the perovskite silicon tandem solar cell.

[0022] Other features and advantages of the present invention will be described in the subsequent specification, and some will become obvious from the specification or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings. Description of the Drawings

[0023] The accompanying drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference signs denote the same components.

[0024] Figure 1 It is a schematic structural diagram of the perovskite-silicon tandem solar cell provided by the present invention;

[0025] Figure 2 It is a scanning electron microscope of the fullerene layer, the modification layer and the buffer layer in the perovskite-silicon tandem solar cell of Example 2 provided by the present invention;

[0026] Figure 3 It is a scanning electron microscope of the fullerene layer, the modification layer and the buffer layer in the perovskite-silicon tandem solar cell of Comparative Example 1;

[0027] Figure 4 It is a physical photograph of Specimen 1 at different times;

[0028] Figure 5 It is a physical photograph of Specimen 2 at different times.

[0029] Reference signs:

[0030] 1 - back electrode; 2 - P-type amorphous silicon layer; 3 - first intrinsic amorphous silicon layer; 4 - N-type silicon substrate; 5 - second intrinsic amorphous silicon layer; 6 - N-type amorphous silicon layer; 7 - transparent conductive layer; 8 - hole transport layer; 9 - perovskite light-absorbing layer; 10 - lithium fluoride layer; 11 - fullerene layer; 12 - modification layer; 13 - buffer layer; 14 - front recombination layer; 15 - positive electrode. Detailed embodiments

[0031] The following will specifically describe the preferred embodiments of the present invention with reference to the accompanying drawings, in which the accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention.

[0032] In the first aspect of the present invention, an electron transport layer for a perovskite-silicon tandem solar cell is provided. The perovskite-silicon tandem solar cell includes a silicon bottom cell. The electron transport layer includes a lithium fluoride layer 10, a fullerene layer 11, a modification layer 12 and a buffer layer 13 that are sequentially stacked along the direction gradually away from the light-receiving surface of the silicon bottom cell. Among them, the material of the modification layer 12 is polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyethylene oxide (PEO), polyimide (PEI) or branched polyethyleneimine (PEIE), that is to say, the modification layer 12 is a polyethylene terephthalate layer, a polymethyl methacrylate layer, a polyethylene oxide layer, a polyimide layer or a branched polyethyleneimine layer.

[0033] Compared with the prior art, for the electron transport layer provided by the present invention, on the basis of ensuring that the electron transport layer has energy levels matching those of the perovskite light-absorbing layer 9 and the function of selectively transporting carriers, a modification layer 12 is added between the fullerene layer 11 and the buffer layer 13. On the one hand, the modification layer 12 is formed of a polymer having nucleophilic functional groups such as hydroxyl, carbonyl, and amino groups. During the subsequent low-temperature atomic layer deposition process of the buffer layer 13, the buffer layer precursor can form chemisorption on the surface of the modification layer 12, which is equivalent to increasing the crystal nuclei for the crystallization of the buffer layer precursor, facilitating the uniform attachment and nucleation of the low-temperature atomic layer deposited buffer layer precursor on the surface of the modification layer 12. This can not only improve the crystallinity of the buffer layer 13 and the carrier transport performance of the buffer layer 13, reduce the water oxygen and ion transport channels in the buffer layer 13, improve the photoelectric conversion efficiency and damp heat stability of the perovskite-silicon tandem solar cell, but also reduce the number of cycles of low-temperature atomic layer deposition, reduce the usage amount of the buffer layer precursor, improve the formation efficiency of the buffer layer 13, and ensure the stability of the perovskite light-absorbing layer 9.

[0034] On the other hand, the setting of the modification layer 12 isolates the fullerene layer 11 and the buffer layer precursor, and the buffer layer precursor cannot diffuse into the fullerene layer 11, thereby ensuring a clear interface between the fullerene layer 11 and the modification layer 12 and improving the photoelectric conversion efficiency of the perovskite-silicon tandem solar cell.

[0035] In order to form an effective modification layer 12 and fully isolate the fullerene layer 11 and the buffer layer precursor, exemplarily, the thickness of the above-mentioned modification layer 12 is 1 to 5 nm.

[0036] In order to further improve the stability of the electron transport layer, the purity of the material of the above-mentioned modification layer 12 is 95.0% or more (for example, 96.0%, 97.0%, 98.0% or 99.0%), and there is no need to additionally dope other substances.

[0037] In order to ensure the photoelectric conversion efficiency of the perovskite-silicon tandem solar cell, exemplarily, the thickness of the electron transport layer is 20 nm to 100 nm (for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm). This is because if the thickness of the electron transport layer is too small, island-like growth will occur, and if the thickness is too large, the transport resistance will increase, thereby affecting the photoelectric conversion efficiency of the perovskite-silicon tandem solar cell.

[0038] It should be noted that the material of the fullerene layer 11 is at least one or two or more of fullerenes or their derivatives. Preferably, from the perspective of cost, the fullerene is fullerene with 60 carbon atoms (C 60 fullerene) or fullerene with 70 carbon atoms (C 70 fullerene).

[0039] For the material of the buffer layer 13, exemplarily, one of titanium dioxide (TiO2), tin oxide (SnO2), zinc oxide (ZnO), or niobium oxide (Nb2O5) is adopted.

[0040] Among them, the conduction band minimum (CBM) of titanium dioxide is -4.1 eV, which is beneficial to electron injection.

[0041] Tin oxide has excellent electrical and optical properties. For example, it has appropriate energy levels, high carrier mobility, and good antireflection ability.

[0042] Zinc oxide is a direct bandgap II-VI group semiconductor material with a bandgap width of 3.3 eV. The conduction band minimum is -4.2 eV, and the exciton binding energy is 60 meV at room temperature. Zinc oxide matches the lowest unoccupied molecular orbital energy level (-3.6 eV) and the highest occupied molecular orbital energy level (-5.2 eV) of CH3NH3PbI3 in terms of energy levels, thereby ensuring the efficiency of electron extraction. Moreover, zinc oxide does not require high-temperature sintering, is easy to be prepared into a large-area thin film, and has a higher electron mobility compared with titanium dioxide.

[0043] As an n-type semiconductor, niobium oxide has an optical bandgap similar to that of common titanium dioxide, zinc oxide, etc., has good electron transport performance, has more advantages in energy level arrangement, and has better chemical stability.

[0044] In the second aspect of the present invention, a perovskite-silicon tandem solar cell is provided. Refer to Figure 1 , which includes a silicon bottom cell, a hole transport layer 8, a perovskite light-absorbing layer 9, an electron transport layer, a front surface recombination layer 14, and a positive electrode 15 that are sequentially stacked on the light-receiving surface of the silicon bottom cell, and a back electrode 1 that is stacked on the backlight surface of the silicon bottom cell. Among them, the electron transport layer is the electron transport layer provided in the first aspect of the present invention.

[0045] It can be understood that the above-mentioned perovskite-silicon tandem solar cell further includes a back conductive grid line electrically connected to the back electrode 1 and a front conductive grid line connected to the positive electrode 15.

[0046] Compared with the prior art, the beneficial effects of the perovskite-silicon tandem solar cell provided by the present invention are basically the same as those of the electron transport layer provided in the first aspect, and will not be elaborated here one by one.

[0047] Exemplarily, the above-mentioned silicon-based battery is a heterojunction type solar cell (HIT, SHJ, Heterojunction with Intrinsic Thinfilm), a passivated emitter and rear cell (PERC cell, Passivated Emitter and Rear Cell), an interdigitated back contact cell (IBC cell, Interdigitated Back Contact Cell), a metal wrap through cell (MWT cell, Metal Wrap Through Cell) or a tunnel oxide passivated contact solar cell (Top-con cell, Tunnel Oxide Passivated Contact Cell).

[0048] From the perspective of adaptability, the above-mentioned silicon-based battery is a heterojunction type solar cell, which can better cooperate with the perovskite light-absorbing layer 9. Correspondingly, the silicon-based battery includes a P-type amorphous silicon layer 2, a first intrinsic amorphous silicon layer 3 (used as the i-layer in the heterojunction type solar cell), an N-type silicon substrate 4, a second intrinsic amorphous silicon layer 5 (used as the i-layer in the heterojunction type solar cell), an N-type amorphous silicon layer 6 and a transparent conductive layer 7 stacked in sequence from the backlight side to the light-receiving side.

[0049] For the material of the hole transport layer 8, specifically, it is a nickel oxide layer modified with [2-(9H-carbazol-9-yl)ethyl]phosphonic acid on the surface, that is, the hole transport layer 8 includes a CuNiO layer and a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (i.e., 2PACz layer) stacked in sequence along the direction gradually away from the light-receiving surface of the silicon-based battery.

[0050] For the material of the perovskite light-absorbing layer 9, it is a material with an ABX3 structure, where A is the first cation, selected from Rb + 、Na + 、K + 、Cs + 、HN=CHNH3 + and CH3NH3 + and at least one of them; B is the second cation, selected from Pb 2+ 、Sr 2+ 、Sn 2 + or Cu 2+ and at least one of them; X is Cl - 、Br - and I - and at least one of them.

[0051] Exemplarily, the material with an ABX3 structure is CH3NH3PbI3, HN=CHNH3PbI3 or Cs0.05 MA 0.1 FA 0.85 Pb(I 0.85 Br 0.15 )3。

[0052] It should be noted that for the above perovskite-silicon tandem solar cell, the thickness parameters of each layer are as follows:

[0053] The thickness of the back electrode 1 is 80 - 120 nm, the thickness of the P-type amorphous silicon layer 2 is 8 - 15 nm, the thickness of the first intrinsic amorphous silicon layer 3 is 8 - 10 nm, the thickness of the N-type silicon substrate 4 is 200 - 250 μm, the thickness of the second intrinsic amorphous silicon layer 5 is 10 - 12 nm, the thickness of the N-type amorphous silicon layer 6 is 8 - 20 nm, the thickness of the transparent conductive layer 7 is 15 - 30 nm, the thickness of the hole transport layer 8 is 20 - 50 nm, the thickness of the perovskite light-absorbing layer 9 is 1 - 5 nm, the thickness of the lithium fluoride layer 10 is 1 - 3 nm, the thickness of the fullerene layer 11 is 5 - 30 nm, the thickness of the modification layer 12 is 1 - 5 nm, the thickness of the buffer layer 13 is 13 - 62 nm, the thickness of the front surface recombination layer 14 is 40 - 200 nm, and the thickness of the positive electrode 15 is 80 - 100 nm.

[0054] In the third aspect of the present invention, a method for preparing a perovskite-silicon tandem solar cell is provided, which is used for preparing the perovskite-silicon tandem solar cell provided in the second aspect. The preparation method includes the following steps:

[0055] Step a: Provide a silicon bottom cell;

[0056] Step b: Sequentially form a hole transport layer 8, a perovskite light-absorbing layer 9, a lithium fluoride layer 10, a fullerene layer 11, a modification layer 12, a buffer layer 13, a front surface recombination layer 14, and a positive electrode 15 on the light-receiving surface of the silicon bottom cell, and form a back electrode 1 on the backlight surface of the silicon bottom cell.

[0057] Compared with the prior art, the beneficial effects of the method for preparing a perovskite-silicon tandem solar cell provided by the present invention are basically the same as those of the perovskite-silicon tandem solar cell provided in the second aspect, and will not be elaborated here one by one.

[0058] Specifically, the formation methods of the above lithium fluoride layer 10, fullerene layer 11, modification layer 12, and buffer layer 13 are as follows:

[0059] The formation method of the lithium fluoride layer 10 adopts electron beam deposition or vacuum thermal evaporation deposition; exemplarily, the formation method of the lithium fluoride layer 10 adopts vacuum thermal evaporation deposition, and the lithium fluoride layer 10 is prepared by using powdered lithium fluoride, and the evaporation rate of lithium fluoride is 0.01 - 0.02 nm / s.

[0060] The formation method of the fullerene layer 11 adopts radio frequency magnetron sputtering, spin coating, spray pyrolysis, atomic layer deposition, thermal oxidation or vacuum thermal evaporation deposition; exemplarily, the formation method of the fullerene layer 11 adopts vacuum thermal evaporation deposition, and the powdered fullerene is used to prepare the fullerene layer 11, and the evaporation rate of the fullerene is 0.02 - 0.03 nm / s.

[0061] The formation method of the modification layer 12 adopts spin coating, spin coating, electrospinning or blade coating; exemplarily, the formation method of the modification layer 12 adopts spin coating. Under the protection atmosphere of nitrogen or inert gas, a mixed solution of a modification layer 12 material and an organic solvent is spin-coated on the fullerene layer 11. The concentration of the modification layer 12 material in the mixed solution is 0.05 - 0.1 mg / mL, the spin coating acceleration is 3000 - 4000 rad / s, the rotation rate is accelerated to 6000 - 8000 rad / min within 2 s, the spin coating time is 25 - 35 s, and after coating, it is heated on a hot stage at 90 - 100 °C for 1 - 5 min to form the modification layer 12.

[0062] The formation method of the buffer layer 13 adopts low-temperature atomic layer deposition, the heating temperature is 90 - 100 °C. In each cycle, the feeding time of the buffer layer precursor is 0.1 - 0.2 s, the evacuation time is 3 - 6 s, the feeding time of the oxygen source is 0.02 - 0.04 s, and the evacuation time is 4 - 6 s.

[0063] Example 1

[0064] In this example, the parameters of each layer of the perovskite-silicon tandem solar cell are as follows:

[0065] The back conductive grid line is a silver grid line, the height of the silver grid line is 20 μm, the width is 50 μm, and the distance between every two silver grid lines is 2 mm; the material of the back electrode is indium tin oxide (ITO), and the thickness is 100 nm; the thickness of the P-type amorphous silicon layer is 15 nm; the thickness of the first intrinsic amorphous silicon layer is 8 nm; the shape of the N-type silicon substrate is square, the planar size is 2 cm × 2 cm, the thickness is 250 μm, and the resistivity is 5 Ω·cm; the thickness of the second intrinsic amorphous silicon layer is 10 nm; the thickness of the N-type amorphous silicon layer is 20 nm; the material of the transparent conductive layer is indium tin oxide (ITO), and the thickness is 20 nm; the thickness of the hole transport layer is 30 nm; the material of the perovskite light-absorbing layer is Cs 0.05 MA 0.1 FA 0.85 Pb(I 0.85 Br 0.15 )3, the thickness is 1 nm; the thickness of the lithium fluoride layer is 1 nm; the material of the fullerene layer is C 60Fullerene, with a thickness of 10 nm; the material of the modification layer is polyimide (PEI), with a thickness of 1 nm; the material of the buffer layer is niobium oxide, with a thickness of 60 nm; the material of the front composite layer is indium zinc oxide (IZO), with a thickness of 50 nm; the material of the positive electrode is indium tin oxide (ITO), with a thickness of 85 nm; the front conductive grid line is a silver grid line, the height of the silver grid line is 20 μm, the width is 50 μm, and the distance between every two silver grid lines is 2 mm.

[0066] The preparation method of the above-mentioned perovskite-silicon tandem solar cell specifically includes the following steps:

[0067] Step 1: Provide a sheet-shaped N-type silicon substrate, place the N-type silicon substrate in a potassium hydroxide solution with a concentration of 2%, and etch it at 80 °C for 15 min to form texture.

[0068] Step 2: On the backlight side and the light-receiving side of the textured N-type silicon substrate, deposit a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer respectively by plasma-enhanced chemical vapor deposition. The flow rates of silane and phosphine are 200 sccm, the radio frequency is 1 MHz, the temperature is 200 °C, and the power is 45 W.

[0069] Step 3: Deposit a layer of P-type amorphous silicon on the first intrinsic amorphous silicon layer to form a P-type amorphous silicon layer, and deposit a layer of N-type amorphous silicon on the second intrinsic amorphous silicon layer to form an N-type amorphous silicon.

[0070] Step 4: Prepare indium tin oxide (ITO) on the N-type amorphous silicon layer by magnetron sputtering to form a transparent conductive layer, and the target material In:Sn = 90:10.

[0071] Step 5: Deposit a layer of CuNiO on the transparent conductive layer by magnetron sputtering to form a CuNiO layer. The target material Cu:Ni = 95:5. Spin-coat an ethanol solution of 2PACz on the surface of the CuNiO layer at a speed of 3000 rad / min. The concentration of the ethanol solution of 2PACz is 1 mg / mL, and anneal it at 100 °C for 1 min to form a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (2PACz layer).

[0072] Step 6: Evaporate and deposit lead iodide and cesium bromide on the surface of the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer at speeds of 0.105 nm / s and 0.015 nm / s respectively to form thin films of lead iodide and cesium bromide. Dissolve FAI and MABr in ethanol at a molar ratio of 10:1, with a total concentration of 1.5 mmol / mL. After complete dissolution, filter through a 0.45-μm polytetrafluoroethylene membrane, and then spin-coat it on the above-mentioned lead iodide and cesium bromide thin films at a speed of 4000 rad / min, maintaining rotation for 30 s. Then, heat it at a temperature of 150 °C and a relative humidity of 50% for 60 min to obtain a perovskite light-absorbing layer;

[0073] Step 7: Prepare a lithium fluoride layer on the perovskite light-absorbing layer by vacuum thermal evaporation deposition using powdered lithium fluoride, with a lithium fluoride evaporation rate of 0.01 nm / s;

[0074] Step 8: Prepare a fullerene layer on the lithium fluoride layer by vacuum thermal evaporation deposition using powdered fullerene, with a fullerene evaporation rate of 0.02 nm / s;

[0075] Step 9: Spin-coat an isopropanol solution of poly(ethylene imine) (PEI) on the fullerene layer in a nitrogen atmosphere. The concentration of the isopropanol solution of poly(ethylene imine) is 0.05 mg / mL; the spin-coating acceleration is 3000 rad / s, and it accelerates to a rotation rate of 6000 rad / min within 2 s. The spin-coating time is 30 s. After coating, heat it on a hot stage at 100 °C for 1 min to form a modification layer;

[0076] Step 10: Use tert-butylimido tris(diethylamino)niobium as the niobium source and pure water as the oxygen source to prepare a niobium oxide buffer layer by low-temperature atomic layer deposition (ALD). The heating temperature is 100 °C. In each cycle, the feeding time of the niobium source is 0.1 s, the evacuation time is 5 s, the feeding time of the oxygen source is 0.02 s, and the evacuation time is 5 s;

[0077] Step 11: Deposit a front composite layer on the surface of the buffer layer by magnetron sputtering process. Then, use reactive plasma deposition to prepare indium tin oxide layers on the surfaces of the p-type amorphous silicon layer and the front composite layer respectively as the back electrode and the front electrode.

[0078] Step 12: Prepare silver grid lines on the back electrode and the front electrode by screen printing.

[0079] Example 2

[0080] In this example, the parameters of each layer of the perovskite / silicon tandem solar cell are as follows:

[0081] The back conductive grid lines are silver grid lines. The height of the silver grid lines is 18 μm, the width is 51 μm, and the distance between every two silver grid lines is 2.5 mm. The material of the back electrode is indium tin oxide (ITO), and the thickness is 120 nm. The thickness of the P-type amorphous silicon layer is 10 nm. The thickness of the first intrinsic amorphous silicon layer is 10 nm. The shape of the N-type silicon substrate is square, the planar size is 2 cm × 2 cm, the thickness is 220 μm, and the resistivity is 4.8 Ω·cm. The thickness of the second intrinsic amorphous silicon layer is 12 nm. The thickness of the N-type amorphous silicon layer is 15 nm. The material of the transparent conductive layer is indium tin oxide (ITO), and the thickness is 30 nm. The thickness of the hole transport layer is 20 nm. The material of the perovskite light-absorbing layer is CH3NH3PbI3, and the thickness is 3.5 nm. The thickness of the lithium fluoride layer is 2 nm. The material of the fullerene layer is C 70 fullerene, and the thickness is 25 nm. The material of the modification layer is branched polyethyleneimine (PEIE), and the thickness is 3.5 nm. The material of the buffer layer is tin oxide, and the thickness is 30 nm. The material of the front composite layer is indium zinc oxide (IZO), and the thickness is 150 nm. The material of the positive electrode is indium tin oxide (ITO), and the thickness is 100 nm. The front conductive grid lines are silver grid lines. The height of the silver grid lines is 18 μm, the width is 51 μm, and the distance between every two silver grid lines is 2.5 mm.

[0082] The preparation method of the above perovskite-silicon tandem solar cell specifically includes the following steps:

[0083] Step 1: Provide a sheet-shaped N-type silicon substrate, place the N-type silicon substrate in a potassium hydroxide solution with a concentration of 2%, and etch it at 90 °C for 10 min to form texture.

[0084] Step 2: Deposit the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer on the backlight side and the light-receiving side of the textured N-type silicon substrate respectively by plasma-enhanced chemical vapor deposition. The flow rates of silane and phosphine are 220 sccm, the radio frequency is 10 MHz, the temperature is 185 °C, and the power is 40 W.

[0085] Step 3: Deposit a layer of P-type amorphous silicon on the first intrinsic amorphous silicon layer to form a P-type amorphous silicon layer, and deposit a layer of N-type amorphous silicon on the second intrinsic amorphous silicon layer to form an N-type amorphous silicon.

[0086] Step 4: Prepare indium tin oxide (ITO) by magnetron sputtering on the N-type amorphous silicon layer to form a transparent conductive layer. The target material In:Sn = 90:10.

[0087] Step 5: Deposit a layer of CuNiO on the transparent conductive layer by magnetron sputtering to form a CuNiO layer. The target material has a Cu:Ni ratio of 95:5. Spin-coat an ethanol solution of 2PACz on the surface of the CuNiO layer at a speed of 3500 rad / min. The concentration of the 2PACz ethanol solution is 1.2 mg / mL. Anneal at 110 °C for 0.5 min to form a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (2PACz layer);

[0088] Step 6: Thermally evaporate and deposit lead iodide and cesium bromide on the surface of the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer at speeds of 0.110 nm / s and 0.018 nm / s respectively to form thin films of lead iodide and cesium bromide. Dissolve FAI and MABr in ethanol at a molar ratio of 8:1 with a total concentration of 1.4 mmol / mL. After complete dissolution, filter through a 0.45 μm polytetrafluoroethylene membrane, and then spin-coat it on the above-mentioned lead iodide and cesium bromide thin films at a rotation speed of 3500 rad / min, maintaining rotation for 40 s. Then heat at a temperature of 160 °C and a relative humidity of 60% for 45 min to obtain a perovskite light-absorbing layer;

[0089] Step 7: Prepare a lithium fluoride layer on the perovskite light-absorbing layer by vacuum thermal evaporation deposition using powdered lithium fluoride. The evaporation rate of lithium fluoride is 0.02 nm / s;

[0090] Step 8: Prepare a fullerene layer on the lithium fluoride layer by vacuum thermal evaporation deposition using powdered fullerene. The evaporation rate of fullerene is 0.03 nm / s;

[0091] Step 9: Spin-coat an isopropanol solution of branched polyethyleneimine (PEIE) on the fullerene layer in a nitrogen atmosphere. The concentration of the branched polyethyleneimine isopropanol solution is 0.08 mg / mL; the spin-coating acceleration is 3500 rad / s, and it accelerates to a rotation speed of 7000 rad / min within 2 s. The spin-coating time is 35 s. After coating, heat on a hot stage at 90 °C for 5 min to form a modification layer;

[0092] Step 10: Use tetra(dimethylamino)tin as the tin source and pure water as the oxygen source to prepare a buffer layer of tin oxide by low-temperature atomic layer deposition (ALD). The heating temperature is 90 °C. In each cycle, the feeding time of the tin source is 0.2 s, the evacuation time is 3 s, the feeding time of the oxygen source is 0.04 s, and the evacuation time is 4 s;

[0093] Step 11: Deposit a front contact layer on the surface of the buffer layer by magnetron sputtering process. Then, use reactive plasma deposition to prepare indium tin oxide layers on the surfaces of the p-type amorphous silicon layer and the front contact layer as the back electrode and the front electrode respectively.

[0094] Step 12: Use screen printing to prepare silver grid lines on the back electrode and the front electrode.

[0095] Example 3

[0096] In this example, the parameters of each layer of the perovskite-silicon tandem solar cell are as follows:

[0097] The back conductive grid line is a silver grid line. The height of the silver grid line is 23 μm, the width is 49 μm, and the distance between every two silver grid lines is 1.9 mm; the material of the back electrode is indium tin oxide (ITO), and the thickness is 80 nm; the thickness of the P-type amorphous silicon layer is 8 nm; the thickness of the first intrinsic amorphous silicon layer is 9.5 nm; the shape of the N-type silicon substrate is square, the planar size is 2 cm × 2 cm, the thickness is 200 μm, and the resistivity is 4.5 Ω·cm; the thickness of the second intrinsic amorphous silicon layer is 10.5 nm; the thickness of the N-type amorphous silicon layer is 10 nm; the material of the transparent conductive layer is indium tin oxide (ITO), and the thickness is 25 nm; the thickness of the hole transport layer is 45 nm; the material of the perovskite light-absorbing layer is HN=CHNH3PbI3, and the thickness is 2.2 nm; the thickness of the lithium fluoride layer is 3 nm; the material of the fullerene layer is C 60 Fullerene, the thickness is 5 nm; the material of the modification layer is polymethyl methacrylate (PMMA), and the thickness is 3 nm; the material of the buffer layer is titanium dioxide (TiO2), and the thickness is 50 nm; the material of the front composite layer is indium zinc oxide (IZO), and the thickness is 180 nm; the material of the front electrode is indium tin oxide (ITO), and the thickness is 95 nm; the front conductive grid line is a silver grid line. The height of the silver grid line is 23 μm, the width is 49 μm, and the distance between every two silver grid lines is 1.9 mm.

[0098] The preparation method of the above perovskite-silicon tandem solar cell specifically includes the following steps:

[0099] Step 1: Provide a sheet-shaped N-type silicon substrate, place the N-type silicon substrate in a potassium hydroxide solution with a concentration of 2%, and etch it at 105 °C for 8 min to perform texturing;

[0100] Step 2: Deposit the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer on the backlight side and the light-receiving side of the textured N-type silicon substrate respectively by plasma-enhanced chemical vapor deposition. The flow rates of silane and phosphine are 205 sccm, the radio frequency is 6 MHz, the temperature is 175 °C, and the power is 44 W;

[0101] Step 3: Deposit a layer of P-type amorphous silicon on the first intrinsic amorphous silicon layer to form a P-type amorphous silicon layer, and deposit a layer of N-type amorphous silicon on the second intrinsic amorphous silicon layer to form an N-type amorphous silicon;

[0102] Step 4: Prepare indium tin oxide (ITO) by magnetron sputtering on the N-type amorphous silicon layer to form a transparent conductive layer, with the target material In:Sn = 90:10;

[0103] Step 5: Deposit a layer of CuNiO by magnetron sputtering on the transparent conductive layer to form a CuNiO layer, with the target material Cu:Ni = 95:5. Spin-coat an ethanol solution of 2PACz on the surface of the CuNiO layer at a speed of 3500 rad / min. The concentration of the ethanol solution of 2PACz is 1.5 mg / mL, and anneal at 105 °C for 1.2 min to form a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (2PACz layer);

[0104] Step 6: Thermally evaporate and deposit lead iodide and cesium bromide on the surface of the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer at speeds of 0.108 nm / s and 0.015 nm / s respectively to form a thin film of lead iodide and cesium bromide. Dissolve FAI and MABr in ethanol at a molar ratio of 8:1, with a total concentration of 1.5 mmol / mL. After complete dissolution, filter through a polytetrafluoroethylene membrane with a pore size of 0.45 μm, and then spin-coat it on the above-mentioned thin film of lead iodide and cesium bromide at a rotation speed of 3750 rad / min, keep rotating for 45 s, and then heat at a temperature of 175 °C and a relative humidity of 55% for 35 min to obtain a perovskite light-absorbing layer;

[0105] Step 7: Prepare a lithium fluoride layer by vacuum thermal evaporation deposition using powdered lithium fluoride on the perovskite light-absorbing layer, with a lithium fluoride evaporation rate of 0.02 nm / s;

[0106] Step 8: Prepare a fullerene layer by vacuum thermal evaporation deposition using powdered fullerene on the lithium fluoride layer, with a fullerene evaporation rate of 0.03 nm / s;

[0107] Step 9: Spin-coat an isopropanol solution of polymethyl methacrylate (PMMA) on the fullerene layer in a nitrogen atmosphere. The concentration of the isopropanol solution of polymethyl methacrylate is 0.10 mg / mL; the spin-coating acceleration is 4000 rad / s, accelerate to a rotation speed of 8000 rad / min within 2 s, and the spin-coating time is 25 s. After coating, heat on a hot stage at 95 °C for 3.5 min to form a modification layer;

[0108] Step 10: Use titanium isopropoxide as the titanium source and pure water as the oxygen source to prepare a titanium dioxide buffer layer by low-temperature atomic layer deposition (ALD). The heating temperature is 95 °C. In each cycle, the feeding time of the titanium source is 0.15 s, the evacuation time is 6 s, the feeding time of the oxygen source is 0.03 s, and the evacuation time is 6 s;

[0109] Step 11: Deposit a front recombination layer on the surface of the buffer layer by magnetron sputtering process. Then, use reactive plasma deposition to prepare indium tin oxide layers on the surfaces of the P-type amorphous silicon layer and the front recombination layer respectively as the back electrode and the front electrode.

[0110] Step 12: Prepare silver grid lines on the back electrode and the front electrode by screen printing.

[0111] Example 4

[0112] In this example, the parameters of each layer of the perovskite / silicon tandem solar cell are as follows:

[0113] The back conductive grid line is a silver grid line. The height of the silver grid line is 20 μm, the width is 45 μm, and the distance between every two silver grid lines is 2.0 mm; the material of the back electrode is indium tin oxide (ITO), and the thickness is 90 nm; the thickness of the P-type amorphous silicon layer is 12 nm; the thickness of the first intrinsic amorphous silicon layer is 10 nm; the shape of the N-type silicon substrate is square, the planar size is 2 cm × 2 cm, the thickness is 235 μm, and the resistivity is 4.9 Ω·cm; the thickness of the second intrinsic amorphous silicon layer is 10 nm; the thickness of the N-type amorphous silicon layer is 10 nm; the material of the transparent conductive layer is indium tin oxide (ITO), and the thickness is 15 nm; the thickness of the hole transport layer is 50 nm; the material of the perovskite light-absorbing layer is HN=CHNH3PbI3, and the thickness is 5 nm; the thickness of the lithium fluoride layer is 2.5 nm; the material of the fullerene layer is C 70 Fullerene, the thickness is 30 nm; the material of the modification layer is polyethylene terephthalate (PET), and the thickness is 5 nm; the material of the buffer layer is zinc oxide (ZnO), and the thickness is 20 nm; the material of the front recombination layer is indium zinc oxide (IZO), and the thickness is 200 nm; the material of the front electrode is indium tin oxide (ITO), and the thickness is 90 nm; the front conductive grid line is a silver grid line. The height of the silver grid line is 20 μm, the width is 45 μm, and the distance between every two silver grid lines is 2.0 mm.

[0114] The preparation method of the above perovskite / silicon tandem solar cell specifically includes the following steps:

[0115] Step 1: Provide a sheet-shaped N-type silicon substrate, place the N-type silicon substrate in a potassium hydroxide solution with a concentration of 2%, and etch it at 95 °C for 15 min for texturing.

[0116] Step 2: Deposit the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer on the backlight side and the light-receiving side of the textured N-type silicon substrate respectively by plasma-enhanced chemical vapor deposition. The flow rates of silane and phosphine are 205 sccm, the radio frequency is 6 MHz, the temperature is 175 °C, and the power is 44 W.

[0117] Step 3: Deposit a layer of p-type amorphous silicon on the first intrinsic amorphous silicon layer to form a p-type amorphous silicon layer, and deposit a layer of n-type amorphous silicon on the second intrinsic amorphous silicon layer to form an n-type amorphous silicon layer;

[0118] Step 4: Prepare indium tin oxide (ITO) by magnetron sputtering on the n-type amorphous silicon layer to form a transparent conductive layer, with the target material In:Sn = 90:10;

[0119] Step 5: Deposit a layer of CuNiO by magnetron sputtering on the transparent conductive layer to form a CuNiO layer, with the target material Cu:Ni = 95:5. Spin-coat an ethanol solution of 2PACz on the surface of the CuNiO layer at a speed of 4000 rad / min. The concentration of the ethanol solution of 2PACz is 1.8 mg / mL, and anneal at 110 °C for 1 min to form a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (2PACz layer);

[0120] Step 6: Thermally evaporate and deposit lead iodide and cesium bromide on the surface of the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer at speeds of 0.108 nm / s and 0.015 nm / s respectively to form thin films of lead iodide and cesium bromide. Dissolve FAI and MABr in ethanol at a molar ratio of 8:1, with a total concentration of 1.6 mmol / mL. After complete dissolution, filter through a polytetrafluoroethylene membrane with a pore size of 0.45 μm, and then spin-coat it on the above-mentioned thin films of lead iodide and cesium bromide at a rotation speed of 3500 rad / min, keep rotating for 50 s, and then heat at a temperature of 150 °C and a relative humidity of 50% for 60 min to obtain a perovskite light-absorbing layer;

[0121] Step 7: Prepare a lithium fluoride layer by vacuum thermal evaporation deposition using powdered lithium fluoride on the perovskite light-absorbing layer, with a lithium fluoride evaporation rate of 0.015 nm / s;

[0122] Step 8: Prepare a fullerene layer by vacuum thermal evaporation deposition using powdered fullerene on the lithium fluoride layer, with a fullerene evaporation rate of 0.025 nm / s;

[0123] Step 9: Spin-coat an isopropanol solution of polymethyl methacrylate (PMMA) on the fullerene layer in a nitrogen atmosphere. The concentration of the isopropanol solution of polymethyl methacrylate is 0.06 mg / mL; the spin-coating acceleration is 3500 rad / s, accelerate to a rotation speed of 7000 rad / min within 2 s, and the spin-coating time is 30 s. After coating, heat on a hot stage at 100 °C for 2 min to form a modification layer;

[0124] Step 10: Using diethylzinc as the zinc source and pure water as the oxygen source, a zinc oxide buffer layer is prepared by low-temperature atomic layer deposition (ALD). The heating temperature is 90 °C. In each cycle, the feeding time of the zinc source is 0.2 seconds, the evacuation time is 3 seconds, the feeding time of the oxygen source is 0.04 seconds, and the evacuation time is 4 seconds;

[0125] Step 11: A front composite layer is deposited on the surface of the buffer layer by magnetron sputtering. Then, indium tin oxide layers are respectively prepared on the surfaces of the p-type amorphous silicon layer and the front composite layer by reactive plasma deposition as the back electrode and the positive electrode.

[0126] Step 12: Silver grid lines are prepared on the back electrode and the positive electrode by screen printing.

[0127] Example 5

[0128] In this example, the parameters of each layer of the perovskite-silicon tandem solar cell are as follows:

[0129] The back conductive grid line is a silver grid line. The height of the silver grid line is 15 μm, the width is 40 μm, and the distance between every two silver grid lines is 1.5 mm; the material of the back electrode is indium tin oxide (ITO), and the thickness is 105 nm; the thickness of the p-type amorphous silicon layer is 13 nm; the thickness of the first intrinsic amorphous silicon layer is 8.5 nm; the shape of the n-type silicon substrate is square, the planar size is 2 cm × 2 cm, the thickness is 210 μm, and the resistivity is 4.6 Ω·cm; the thickness of the second intrinsic amorphous silicon layer is 11 nm; the thickness of the n-type amorphous silicon layer is 8 nm; the material of the transparent conductive layer is indium tin oxide (ITO), and the thickness is 28 nm; the thickness of the hole transport layer is 40 nm; the material of the perovskite light-absorbing layer is HN=CHNH3PbI3, and the thickness is 5 nm; the thickness of the lithium fluoride layer is 1.5 nm; the material of the fullerene layer is C 60 Fullerene, the thickness is 20 nm; the material of the modification layer is polyethylene oxide (PEO), and the thickness is 5 nm; the material of the buffer layer is tin oxide (SnO2), and the thickness is 15 nm; the material of the front composite layer is indium zinc oxide (IZO), and the thickness is 40 nm; the material of the positive electrode is indium tin oxide (ITO), and the thickness is 95 nm; the front conductive grid line is a silver grid line. The height of the silver grid line is 15 μm, the width is 40 μm, and the distance between every two silver grid lines is 1.5 mm.

[0130] The preparation method of the above perovskite-silicon tandem solar cell specifically includes the following steps:

[0131] Step 1: Provide a sheet-shaped n-type silicon substrate, place the n-type silicon substrate in a potassium hydroxide solution with a concentration of 2%, and etch it at 95 °C for 15 min to form texture;

[0132] Step 2: Deposit a first intrinsic amorphous silicon layer and a second intrinsic amorphous silicon layer on the backlight side and the light-receiving side of the textured N-type silicon substrate respectively by plasma-enhanced chemical vapor deposition. The flow rates of silane and phosphine are 205 sccm, the radio frequency is 6 MHz, the temperature is 175 °C, and the power is 44 W;

[0133] Step 3: Deposit a layer of P-type amorphous silicon on the first intrinsic amorphous silicon layer to form a P-type amorphous silicon layer, and deposit a layer of N-type amorphous silicon on the second intrinsic amorphous silicon layer to form an N-type amorphous silicon;

[0134] Step 4: Prepare indium tin oxide (ITO) on the N-type amorphous silicon layer by magnetron sputtering to form a transparent conductive layer, with the target material In:Sn = 90:10;

[0135] Step 5: Deposit a layer of CuNiO on the transparent conductive layer by magnetron sputtering to form a CuNiO layer, with the target material Cu:Ni = 95:5. Spin-coat an ethanol solution of 2PACz on the surface of the CuNiO layer at a speed of 4000 rad / min. The concentration of the ethanol solution of 2PACz is 1.8 mg / mL, and anneal it at 110 °C for 1 min to form a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer (2PACz layer);

[0136] Step 6: Thermally evaporate and deposit lead iodide and cesium bromide on the surface of the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid layer at speeds of 0.108 nm / s and 0.015 nm / s respectively to form thin films of lead iodide and cesium bromide. Dissolve FAI and MABr in ethanol at a molar ratio of 8:1, with a total concentration of 1.6 mmol / mL. After complete dissolution, filter it through a polytetrafluoroethylene membrane with a pore size of 0.45 μm, and then spin-coat it on the above-mentioned thin films of lead iodide and cesium bromide at a rotation speed of 3500 rad / min, keep rotating for 50 s, and then heat it at a temperature of 150 °C and a relative humidity of 50% for 60 min to obtain a perovskite light-absorbing layer;

[0137] Step 7: Prepare a lithium fluoride layer by vacuum thermal evaporation deposition using powdered lithium fluoride on the perovskite light-absorbing layer, with a lithium fluoride evaporation rate of 0.01 nm / s;

[0138] Step 8: Prepare a fullerene layer by vacuum thermal evaporation deposition using powdered fullerene on the lithium fluoride layer, with a fullerene evaporation rate of 0.02 nm / s;

[0139] Step 9: Spin-coat an isopropanol solution of polyethylene oxide (PEO) on the fullerene layer in a nitrogen atmosphere. The concentration of the polyethylene oxide isopropanol solution is 0.05 mg / mL; the spin-coating acceleration is 3500 rad / s, and it accelerates to a rotation rate of 7000 rad / min within 2 s. The spin-coating time is 30 s. After coating, heat it on a hot stage at 100 °C for 2 min to form a modification layer;

[0140] Step 10: Use tin tetrakis(dimethylamino) as the tin source and pure water as the oxygen source to prepare a buffer layer of tin oxide by low-temperature atomic layer deposition (ALD). The heating temperature is 100 °C. In each cycle, the feeding time of the tin source is 0.1 s, the evacuation time is 5 s, the feeding time of the oxygen source is 0.02 s, and the evacuation time is 5 s;

[0141] Step 11: Deposit a front composite layer on the surface of the buffer layer by magnetron sputtering process. Then, use reactive plasma deposition to prepare indium tin oxide layers on the surfaces of the p-type amorphous silicon layer and the front composite layer as the back electrode and the positive electrode respectively.

[0142] Step 12: Prepare silver grid lines on the back electrode and the positive electrode by screen printing.

[0143] Comparative Example 1

[0144] The preparation method of Comparative Example 1 is basically the same as that of Example 2, except that: Step 9 is not included, and a layer of tin oxide is directly prepared on the fullerene layer by atomic layer deposition (ALD) using tin tetrakis(dimethylamino) (TDMASn) as the tin source and pure water as the oxygen source.

[0145] Under standard test conditions (AM1.5, 25 °C, 1000 W / m 2 ), the electrical properties of the perovskite-silicon tandem solar cells prepared in Examples 1-5 and Comparative Example 1 are tested. For example, short-circuit current density (J sc ), open-circuit voltage (V oc ), conversion efficiency (Eff) and fill factor (FF). The test structure is shown in Table 1.

[0146] Table 1 Comparison table of electrical properties of Examples 1-5 and Comparative Example 1

[0147]

[0148]

[0149] As can be seen from Table 1, the electrical properties of the perovskite-silicon tandem solar cells prepared in Examples 1-5 are significantly better than those of Comparative Example 1. Specifically, the short-circuit current of the perovskite-silicon tandem solar cells prepared in the present invention is 20.10-20.50 mA / cm 2, the open-circuit voltage is 1.85 - 1.89 V, the fill factor is 80.83 - 81.05%, and the conversion efficiency is 30.00 - 31.00%.

[0150] The damp heat stability tracking test of the perovskite / silicon tandem solar cells prepared in Examples 1 - 5 and Comparative Example 1 was carried out for 100 hours. The test was carried out under standard test conditions, and the storage conditions were 85% RH and 50 °C. The ratio of the performance loss (attenuation ratio) of the perovskite / silicon tandem solar cells prepared in Examples 1 - 5 and Comparative Example 1 after 100 hours to the initial performance is shown in Table 2.

[0151] Table 2 Comparison table of attenuation ratios of Examples 1 - 5 and Comparative Example 1 after 100 hours

[0152] Attenuation ratio (%) Example 1 5.4 Example 2 5.8 Example 3 5.0 Example 4 5.5 Example 5 5.1 Comparative Example 1 31.1

[0153] It can be seen from Table 2 that the stability of the perovskite / silicon tandem solar cells prepared in Examples 1 - 5 under damp heat stress is significantly better than that of Comparative Example 1. Specifically, the attenuation ratio is 5.0 - 5.8%.

[0154] Figure 2 Scanning electron microscope images of the fullerene layer, modification layer, and buffer layer in the perovskite / silicon tandem solar cell of Example 2. Figure 3 Scanning electron microscope images of the fullerene layer and buffer layer in the perovskite / silicon tandem solar cell of Comparative Example 1 for comparison. Figure 2 and Figure 3 It can be clearly seen that the interfaces between the fullerene layer, modification layer, and buffer layer in Example 2 are clearly visible, while the interface between the fullerene layer and buffer layer in Comparative Example 1 is not clear.

[0155] In order to verify the water resistance of the electron transport layer, Specimen 1 was prepared according to Steps 1 to 10 of Example 2, and Specimen 2 was prepared according to Steps 1 to 10 of Comparative Example 1. Water droplets were dropped on the surfaces of Specimen 1 and Specimen 2 respectively for water resistance performance testing. Figure 4 Physical photos of Specimen 1 at different times. Figure 5 Physical photos of Specimen 2 at different times for comparison. Figure 4 and Figure 5 It can be clearly seen that from 0 min to 10 min, there is basically no color change in Specimen 1, indicating that water has not penetrated into the perovskite light-absorbing layer. The area of color change in Specimen 2 gradually increases, indicating that water has penetrated into the perovskite light-absorbing layer over a large area.

[0156] As described above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An electron transport layer for a perovskite silicon tandem solar cell, wherein the perovskite silicon tandem solar cell comprises a silicon bottom cell, characterized in that: The electron transport layer comprises a lithium fluoride layer, a fullerene layer, a modification layer and a buffer layer which are sequentially stacked along a direction gradually away from the light-receiving surface of the silicon bottom cell; The modification layer material is polyethylene terephthalate, polymethyl methacrylate, polyethylene oxide, polyacetimide or branched polyethyleneimine.

2. The electron transport layer according to claim 1, characterized in that The thickness of the modified layer is 1-5 nm.

3. The electron transport layer according to claim 1 or 2, characterized in that The thickness of the lithium fluoride layer is 1 to 3 nm; and / or, the thickness of the fullerene layer is 5 to 30 nm; And / or, the buffer layer has a thickness of 13-62 nm.

4. The electron transport layer according to claim 1, characterized in that The material of the fullerene layer is at least one or two or more of fullerene or fullerene derivatives; And / or, the material of the buffer layer is one of titanium dioxide, tin oxide, zinc oxide or niobium oxide.

5. A perovskite silicon tandem solar cell, comprising a silicon bottom cell, a hole transport layer, a perovskite light absorption layer, an electron transport layer, a front recombination layer and a positive electrode stacked in sequence on the light-receiving surface of the silicon bottom cell, and a back electrode stacked on the backlight surface of the silicon bottom cell, characterized in that: The electron transport layer is the electron transport layer according to any one of claims 1 to 4.

6. A method for preparing a perovskite silicon tandem solar cell, characterized in that: For the preparation of the perovskite silicon tandem solar cell according to claim 5, the preparation method comprises the following steps: Step a: providing a silicon bottom cell; Step b: forming a hole transport layer, a perovskite light absorption layer, a lithium fluoride layer, a fullerene layer, a modification layer, a buffer layer, a front composite layer and a positive electrode in sequence on the light-receiving side of the silicon bottom cell, and forming a back electrode on the backlight side of the silicon bottom cell.

7. The method for preparing a perovskite silicon tandem solar cell according to claim 6, characterized in that: The lithium fluoride layer is formed by vacuum thermal evaporation deposition, and the evaporation rate of the lithium fluoride is 0.01-0.02 nm / s.

8. The method for preparing a perovskite silicon tandem solar cell according to claim 6, characterized in that: The method for forming the fullerene layer adopts vacuum thermal evaporation deposition, and the evaporation rate of the fullerene is 0.02-0.03 nm / s.

9. The method for preparing a perovskite silicon tandem solar cell according to claim 6, characterized in that: The modification layer is formed by spin coating. In a nitrogen or inert gas protective atmosphere, a mixed solution of a modification layer material and an organic solvent is spin-coated on the fullerene layer, and a modification layer is formed after heating; The concentration of the modification layer material in the mixed solution is 0.05-0.1 mg / mL, the spin coating acceleration is 3000-4000 rad / s, the spin coating rate is 6000-8000 rad / min, the spin coating time is 25-35 s, the heating temperature is 90-100° C., and the heating time is 1-5 min.

10. The method for preparing a perovskite silicon tandem solar cell according to claim 6, characterized in that: The buffer layer formation method adopts low-temperature atomic layer deposition, the heating temperature is 90-100°C, in each cycle, the feeding time of the buffer layer precursor is 0.1-0.2 seconds, the emptying time is 3-6 seconds, the feeding time of water is 0.02-0.04 seconds, and the emptying time is 4-6 seconds.

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