Perovskite / crystalline silicon laminated solar cell and preparation method thereof

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a perovskite / crystalline silicon laminated solar cell and a preparation method thereof. The perovskite / crystalline silicon laminated solar cell comprises a crystalline silicon bottom cell and a perovskite top cell, the surface of one side, close to the perovskite top cell, of the crystalline silicon bottom cell is provided with a suede structure, the suede structure comprises a fluctuating structure, and the average height of the fluctuating structure is 1-4 [mu] m; the perovskite top cell comprises a perovskite light absorption layer, and the molar ratio of Pb < 2 + > to Cs < + > in the perovskite light absorption layer is 2: 1-7: 1. The average thickness D of the perovskite light absorption layer and the average height h of the fluctuating structure meet the formula: D = (0.25-0.65) h. By controlling the height of the fluctuating structure, the molar ratio of Pb to Cs in perovskite and the ratio of the thickness of the perovskite layer to the height of the fluctuating structure, the inorganic framework layer with the porous and shape-preserving morphology is obtained, the inorganic framework layer can easily react with subsequently deposited organic salt, and the high-quality perovskite thin film is formed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photovoltaics, and particularly relates to a perovskite / crystalline silicon tandem solar cell and a preparation method thereof. BACKGROUND

[0002] Perovskite / crystalline silicon (PVK / Si) tandem cells are considered as a new type of high-efficiency photovoltaic technology due to their ultra-high conversion efficiency. The conformal preparation of a perovskite top cell on an industrialized textured crystalline silicon bottom cell has the advantages of high current density, process matching and compatibility.

[0003] Most of the existing technologies related to the morphology of the perovskite light-absorbing layer only study from the single factor angle of the composition (such as the element ratio) or structure (such as the thickness) of the perovskite light-absorbing layer, but this cannot guarantee the conformal morphology of the perovskite light-absorbing layer. In addition, relying on single-factor control cannot achieve uniform deposition of the organic layer, resulting in problems such as poor perovskite crystal quality and interface defects.

[0004] Therefore, there is a need in the art for a perovskite / crystalline silicon tandem solar cell with a perovskite light-absorbing layer having a conformal morphology and a preparation method thereof. SUMMARY

[0005] To solve the problems existing in the prior art, the present application prepares an inorganic framework layer with a specific lead / cesium molar ratio on a crystalline silicon bottom cell with a specific height textured structure, obtains a porous and conformal inorganic framework layer structure, and controls the ratio of the thickness of the perovskite light-absorbing layer to the height of the textured structure, thereby obtaining a perovskite / crystalline silicon tandem solar cell with a perovskite light-absorbing layer having a conformal morphology.

[0006] Specifically, the present application provides a perovskite / crystalline silicon tandem solar cell, which comprises a crystalline silicon bottom cell and a perovskite top cell.

[0007] The surface of the crystalline silicon bottom cell close to the perovskite top cell side has a textured structure, and the textured structure comprises a relief structure, and the average height of the relief structure is 1-4 μm.

[0008] The perovskite top cell comprises a perovskite light-absorbing layer, and the perovskite light-absorbing layer comprises a perovskite structure material, and the perovskite structure material comprises a first cation and a second cation, wherein the first cation comprises an organic cation and Cs + , and the second cation comprises Pb 2+ , and the molar ratio of Pb 2+ to Cs + in the perovskite light-absorbing layer is 2:1-7:1.

[0009] The average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure satisfy: D = (0.25-0.65)h.

[0010] In one or more embodiments, the molar ratio of Pb 2+ to Cs + is 4:1-5:1.

[0011] In one or more embodiments, the average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure satisfy: D = (0.4-0.6)h.

[0012] In one or more embodiments, the average height of the relief structure is 1.5-2.5 μm.

[0013] In one or more embodiments, the average height of the relief structure is obtained by a method comprising the following steps: selecting at least two regions with a width of 20 μm of the textured structure in a cross-sectional electron microscope image of the crystalline silicon bottom cell, and respectively counting the height of each relief structure in each selected region, and taking the average value.

[0014] In one or more embodiments, the average height of the relief structure is measured in at least 10 selected regions, and the average height of the relief structure in more than 80% of the selected regions falls within 1-4 μm or 1.5-2.5 μm, and the average height of the relief structure is considered to be within 1-4 μm or 1.5-2.5 μm.

[0015] In one or more embodiments, the average thickness of the perovskite light-absorbing layer is obtained by a method comprising the following steps: selecting at least two regions with a width of 20 μm of the textured structure in a cross-sectional electron microscope image of the perovskite / crystalline silicon stacked solar cell, and respectively counting the maximum thickness and the minimum thickness of the perovskite light-absorbing layer on each relief structure in each selected region, and taking the average value.

[0016] In one or more embodiments, the relief structure comprises one or both of a pyramid structure and a wave-shaped structure.

[0017] In one or more embodiments, the organic cation is selected from one or more of formamidinium ion, methylamine ion and dimethylamine ion.

[0018] In one or more embodiments, the perovskite light-absorbing layer has a conformal morphology.

[0019] In one or more embodiments, the maximum thickness D1 and the minimum thickness D2 of the perovskite light-absorbing layer on any one relief structure satisfy D2≥0.6D1.

[0020] In one or more embodiments, the perovskite structure material further comprises anions selected from one or more of halide ions, CN - , OCN - , SeCN - , SCN - , and BF4 - .

[0021] In one or more embodiments, the halide ions are selected from one or more of fluoride ions, chloride ions, bromide ions, and iodide ions.

[0022] The present application also provides a solar cell module comprising the perovskite / crystalline silicon tandem solar cell described in any one of the embodiments herein.

[0023] The present application also provides a method for preparing the perovskite / crystalline silicon tandem solar cell described in any one of the embodiments herein, the method comprising:

[0024] (1) using a crystalline silicon cell with a surface having a textured structure comprising a relief structure as a bottom cell;

[0025] (2) preparing a charge transport layer over the surface of the bottom cell having a textured structure;

[0026] (3) preparing an inorganic skeleton layer over the charge transport layer by an evaporation method, depositing an organic salt on the inorganic skeleton layer, and obtaining a perovskite light-absorbing layer through annealing.

[0027] In one or more embodiments, in step (3), the evaporation method of the inorganic skeleton layer is co-evaporation.

[0028] In one or more embodiments, in step (3), the deposition method of the organic salt is a solution method, an evaporation method, or a sublimation method, and the solution method comprises one or more of a spin coating method, a slot-die coating method, a doctor blade coating method, an ultrasonic spray method, and an inkjet printing method.

[0029] In one or more embodiments, in step (3), the deposition method of the organic salt is an evaporation method.

[0030] In one or more embodiments, in step (3), the annealing temperature is 80-200°C, and the annealing time is 1-30 min.

[0031] In one or more embodiments, step (2) comprises: first preparing a composite layer on the surface of the bottom cell having a textured structure, and then preparing a charge transport layer on the surface of the composite layer.

[0032] In one or more embodiments, in step (2), the charge transport layer is a hole transport layer.

[0033] The present application finds that the following three features play a synergistic role in obtaining a perovskite / crystalline silicon tandem solar cell with a perovskite light-absorbing layer having a conformal morphology: (1) the average height of the textured structure is 1-4 μm; (2) the molar ratio of Pb 2+ to Cs + is 2:1-7:1; and (3) the average thickness D of the perovskite light-absorbing layer and the average height h of the textured structure satisfy D=(0.25-0.65)h. The mechanism of the synergistic effect is as follows: first, the use of a textured structure with an average height of 1-4 μm retains a good light-trapping structure for the cell and is conducive to the deposition of a perovskite top cell with a suitable thickness on the surface of the silicon bottom cell, which meets the requirements of industrialization; maintaining a suitable molar ratio of Pb to Cs is conducive to the formation of an inorganic framework layer with a conformal morphology, which in turn facilitates the subsequent reaction of an organic salt with the inorganic framework layer to form a perovskite light-absorbing layer with a good conformal morphology; if the molar ratio of Pb to Cs is too high, the inorganic framework layer is prone to form a too loose structure, which cannot form a conformal morphology and affects the deposition of the organic salt layer on the inorganic salt layer, making it difficult to obtain a conformal perovskite light-absorbing layer; if the molar ratio of Pb to Cs is too low, the inorganic salt layer will form a too dense structure, which is not conducive to the subsequent diffusion reaction of the organic salt; on the basis of the molar ratio of Pb to Cs and within the range of the average height of the textured structure, the average thickness of the perovskite light-absorbing layer is controlled to maintain a good conformal morphology; if the thickness of the perovskite layer is too thick relative to the height of the textured pyramid, the perovskite layer will accumulate too thickly between the bottoms of the pyramids and be too thin at the tips of the pyramids, resulting in a poor conformal morphology; if the thickness of the perovskite layer is too thin relative to the height of the textured pyramid, the perovskite material is difficult to uniformly cover the textured pyramid, which also affects the conformal morphology. Therefore, the above three points synergistically form a perovskite layer with a conformal morphology on the textured pyramid of crystalline silicon. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 FIG. 1 is a schematic diagram of the conformal morphology structure of the perovskite light-absorbing layer in some embodiments.

[0035] Figure 2 FIG. 2 is an electron microscope image of the perovskite light-absorbing layer in Example 1, in which the maximum thickness D1 and the minimum thickness D2 of the perovskite light-absorbing layer on one side of a textured structure satisfy D2=0.88D1.

[0036] Figure 3 FIG. 4 is an electron microscope image of the inorganic framework layer in Example 2.

[0037] Figure 4 FIG. 5 is an electron microscope image of the inorganic framework layer of Comparative Example 4 (Pb:Cs=8:1), Example 11 (Pb:Cs=7:1), Example 2 (Pb:Cs=5:1), Example 3 (Pb:Cs=4:1), Example 10 (Pb:Cs=2:1), and Comparative Example 7 (Pb:Cs=1:1).

[0038] Figure 5 TEM image of perovskite light absorbing layer of Comparative Example 1.

[0039] Figure 6 TEM image of perovskite light absorbing layer of Comparative Example 2.

[0040] Figure 7 TEM image of perovskite light absorbing layer of Comparative Example 3.

[0041] Figure 8 TEM image of perovskite light absorbing layer of Comparative Example 7. DETAILED DESCRIPTION

[0042] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein are in the ordinary meaning understood by those skilled in the art of the present application, and in the event of conflict, the definition in the specification shall prevail.

[0043] Theories or mechanisms described and disclosed herein, whether or not correct, should not limit the scope of the present application in any way, i.e. the present application can be practiced without relying on any particular theory or mechanism.

[0044] Herein, "comprise", "include", "contain" and similar phrases encompass the meaning of "consist essentially of" and "consist of", e.g. when it is disclosed herein that "A comprises B and C", it should be considered that "A consists essentially of B and C" and "A consists of B and C" are disclosed herein.

[0045] Herein, all features defined by numerical ranges or percentage ranges, such as values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0046] Herein, unless otherwise specified, percentages refer to mass percentages and ratios refer to mass ratios.

[0047] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present application to these embodiments or examples. Rather, all alternatives, modifications, equivalents and equivalents of the methods and materials described herein are intended to be encompassed by the scope of the claims.

[0048] In this document, all possible combinations between features of the various embodiments or examples are not described, in order to avoid obscuring the presentation of the embodiments or examples. Therefore, any feature of the various embodiments or examples can be combined with any other feature of the various embodiments or examples, unless otherwise indicated or unless there are any conflicts or contradicts.

[0049] In the present application, "porous" refers to a material having holes disposed therein. For example, in a porous inorganic skeleton layer, the holes are portions within the porous skeleton layer that do not have skeleton material. Each hole can have the same size or different sizes. The size of a hole is defined as "pore size". For most phenomena involving a porous solid, the limiting size of a hole is the size of its smallest dimension, without any further precision, referring to the width of the hole (i.e. the width of a slit-shaped hole, the diameter of a cylindrical or spherical hole, etc.).

[0050] In the present application, "evaporation method" refers to a method in which a raw material is evaporated by high-temperature heating and then deposited onto a substrate surface.

[0051] In the present application, "solution method" refers to a method in which a raw material is dissolved in a solvent and then deposited onto a substrate surface.

[0052] In the present application, "relief structure" refers to a structure in which a surface of a textured structure is uneven. In the present application, a relief structure refers to a structure between two adjacent highest points on a textured structure.

[0053] In the present application, "wavy structure" refers to a structure in which the top and / or bottom of a pyramid structure is changed from a sharp shape to a circular arc shape.

[0054] In the present application, the height of a relief structure refers to the distance between the highest point and the lowest point of a relief structure in the vertical direction, as shown by h in Figure 1 In the present application, the average height of a relief structure is measured as follows: in a cross-sectional electron microscope image of a crystalline silicon bottom cell, a region with a textured structure width of 20 μm is selected, and the heights of the relief structures (e.g. pyramid structures, wavy structures) in this region are counted and averaged. In the present application, the average height of the relief structures in at least 10 regions is measured, and if the average height of the relief structures in more than 80% of the regions falls within a certain range (e.g. 1-4 μm or 1.5-2.5 μm), the average height of the relief structures is considered to be within the range (e.g. 1-4 μm or 1.5-2.5 μm). When selecting the regions, regions with stable textured structure size of the crystalline silicon cell should be selected, and the edge regions of the crystalline silicon cell should be avoided.

[0055] In the present application, the thickness of the perovskite light-absorbing layer refers to the size of the perovskite light-absorbing layer in the direction perpendicular to the surface of the relief structure, as shown by t in Figure 1D in the formula. In the present application, the average thickness of the perovskite light-absorbing layer is measured as follows: a region with a width of 20 μm of the textured structure is taken in a cross-sectional electron microscope photo of the perovskite / crystalline silicon stacked solar cell, the maximum thickness and the minimum thickness of the perovskite light-absorbing layer on each relief structure in the region are counted, and the average value thereof is taken.

[0056] The present application provides a perovskite / crystalline silicon stacked solar cell, comprising a crystalline silicon bottom cell and a perovskite top cell.

[0057] The perovskite / crystalline silicon stacked solar cell of the present application can be a two-terminal stacked cell or a three-terminal stacked cell.

[0058] In the present application, the crystalline silicon bottom cell can be a PERC cell, a TOPCon cell, an HJT cell or a BC cell.

[0059] In the present application, the crystalline silicon bottom cell has a textured structure, and the textured structure comprises a relief structure. The average height of the relief structure is 1-4 μm, for example, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, and preferably 1.5-2.5 μm. The present application controls the average height of the relief structure in the range of 1-4 μm, preferably 1.5-2.5 μm, which can not only ensure good light trapping capability of the device, but also facilitate the regular growth of the subsequent perovskite thin film.

[0060] In the present application, the perovskite top cell comprises a perovskite light-absorbing layer with a structural formula of ABX3. In the formula, A is a first cation, B is a second cation, and X is an anion. X is selected from one or more of halogen ions, CN - , OCN - , SeCN - , SCN - and BF4 - , A comprises an organic cation and Cs + , and B comprises Pb 2+ . In the present application, the molar ratio of Pb 2+ to Cs + is 2:1-7:1, for example, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, and preferably 4:1-5:1. The present application controls the molar ratio of Pb 2+ to Cs + in the range of 2:1-7:1, preferably 4:1-5:1, which is conducive to the formation of a porous and conformal inorganic skeleton layer morphology. The porous inorganic skeleton layer is conducive to the diffusion and reaction of inorganic salts into the inorganic skeleton layer, forming a high-quality perovskite thin film.

[0061] In some embodiments, the organic cations in the perovskite light-absorbing layer comprise one or more of formamidinium ions, methylamine ions and dimethylamine ions. In some embodiments, X in the perovskite light-absorbing layer is selected from halide ions, preferably one or more of fluoride ions, chloride ions, bromide ions and iodide ions.

[0062] In the present application, the average thickness of the perovskite light-absorbing layer is 250-2600 nm, for example 300 nm, 350 nm, 375 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1625 nm, 1650 nm, 1700 nm, 1800 nm, 1900 nm, 2000 nm, 2100 nm, 2200 nm, 2300 nm, 2400 nm, 2500 nm, preferably 375-1625 nm. In the present application, the average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure satisfy: D = (0.25-0.65)h. If the thickness of the perovskite light-absorbing layer is too thin relative to the height of the relief structure, the perovskite will not be able to absorb enough light, resulting in a low current density of the perovskite / crystalline silicon stacked cell. If the thickness of the perovskite light-absorbing layer is too thick relative to the height of the relief structure, the perovskite will accumulate on the relief structure, failing to obtain a conformal morphology and insufficient reaction at the bottom interface, thereby resulting in poor device performance. In some preferred embodiments, the average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure preferably satisfy: D = (0.4-0.6)h, which is conducive to obtaining a perovskite light-absorbing layer with a better conformal morphology.

[0063] In the present application, the average height of the relief structure is controlled in 1-4 μm, which ensures the minimum thickness of the perovskite that can be deposited, and also ensures the better light trapping effect of the device. At the same time, in the process of preparing the perovskite thin film, the present application also controls the molar ratio of Pb / Cs in the inorganic salt layer to satisfy 2:1-7:1 and the average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure satisfy D=(0.25-0.65)h, so as to obtain the conformal perovskite light-absorbing layer morphology. When the molar ratio of Pb / Cs is higher than 7:1, the content of lead salt in the inorganic skeleton layer is high, the thin film lacks monovalent cations and becomes amorphous inorganic thin film, which presents a too loose and non-conformal morphology, affecting the conformal growth of the subsequent perovskite thin film; when the molar ratio of Pb / Cs is lower than 2:1, the content of lead salt and monovalent cations in the inorganic skeleton layer is close to the stoichiometric ratio, which tends to form a quasi-inorganic perovskite layer, which presents a too dense polycrystalline thin film layer morphology, which makes the diffusion reaction of the subsequent organic salt difficult, and it is impossible to obtain a high-quality perovskite thin film with a conformal morphology. If the average thickness D of the perovskite light-absorbing layer is too thin relative to the average height of the relief structure (D<0.25h), it will be difficult for the perovskite light-absorbing layer to completely cover the relief structure, and it is impossible to obtain a perovskite light-absorbing layer with a conformal morphology; if the average thickness D of the perovskite light-absorbing layer is too thick relative to the average height of the relief structure (D>0.65h), the perovskite will accumulate on the relief structure, and it is also impossible to obtain a perovskite light-absorbing layer with a conformal morphology. The better conformal morphology can obtain a high-quality perovskite thin film on the complex crystalline silicon surface morphology, and can also enhance the light trapping ability of the perovskite / crystalline silicon stacked cell and improve the current of the device. In some preferred embodiments, the average height of the relief structure is controlled in 1.5-2.5 μm.

[0064] In the present application, "conformal" refers to an object that is substantially the same in form or shape as another object. In other words, the morphology of the conformal morphology is such that the thickness between a layer and the surface on which the layer is formed is approximately constant. More specifically, the conformal morphology of the present application can be defined as: the maximum thickness of the perovskite light-absorbing layer on any one relief structure is D1 and the minimum thickness is D2, which satisfy D2≥0.6D1. This case is observed by cross-sectional SEM test, and any one relief structure in the visible range of any one SEM picture satisfies D2≥0.6D1. In some preferred embodiments, the maximum thickness of the perovskite light-absorbing layer on any one relief structure is D1 and the minimum thickness is D2, which satisfy D2≥0.65D1, for example, D2≥0.7D1, D2≥0.75D1, D2≥0.8D1, D2≥0.85D1, D2≥0.9D1.

[0065] In some embodiments, the perovskite light-absorbing layer is formed by depositing an organic salt on the inorganic skeleton layer, and the inorganic skeleton layer comprises Cs +, Pb 2+ and anions (e.g. one or more selected from halide ions, CN - , OCN - , SeCN - , SCN - and BF4 - ), the organic salt comprising anions (e.g. one or more selected from halide ions, CN - , OCN - , SeCN - , SCN - and BF4 - ) and organic cations (e.g. one or more selected from formamidinium ions, methylamine ions and dimethylamine ions).

[0066] In some embodiments, the average thickness of the inorganic framework layer is 125-1300 nm, for example 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm.

[0067] In some preferred embodiments, the average thickness d of the inorganic framework layer and the average height h of the relief structure satisfy: d = (0.125-0.325)h, controlling d and h within the above relationship facilitates the formation of a conformal structure, ensuring the conformal morphology of the perovskite light-absorbing layer, and further improving the quality of the perovskite thin film of the perovskite light-absorbing layer.

[0068] The present application also provides a preparation method of a perovskite / crystalline silicon stacked solar cell, to improve the quality of the perovskite thin film of the perovskite light-absorbing layer, and further improve the performance of the device. The preparation method of the perovskite / crystalline silicon stacked solar cell of the present application comprises:

[0069] (1) using a crystalline silicon cell with a surface having a textured structure as a bottom cell, the textured structure comprising a relief structure, the average height of the relief structure being 1-4 μm, preferably 1.5-2.5 μm;

[0070] (2) preparing a first charge transport layer on the surface of the bottom cell having the textured structure; the first charge transport layer is a hole transport layer or an electron transport layer, preferably a hole transport layer;

[0071] (3) preparing an inorganic framework layer on the first charge transport layer by an evaporation method; the inorganic framework layer comprises Cs + , Pb 2+ and halide ions, Pb 2+The molar ratio of Cs + is 2:1-7:1 (for example, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, preferably 4:1-5:1); the organic salt is deposited on the inorganic skeleton layer, and a perovskite light-absorbing layer is obtained by annealing.

[0072] In some embodiments, step (2) comprises: first preparing a composite layer on the surface of the bottom cell having a textured structure, and then preparing a first charge transport layer on the surface of the composite layer.

[0073] In some embodiments, the method for preparing the perovskite / crystalline silicon tandem solar cell of the present application further comprises:

[0074] (4) preparing a second charge transport layer above the perovskite light-absorbing layer; the second charge transport layer is a hole transport layer or an electron transport layer, preferably an electron transport layer; the second charge transport layer and the first charge transport layer are not simultaneously a hole transport layer or an electron transport layer.

[0075] (5) preparing a transparent electrode and a metal electrode on the side of the second charge transport layer away from the perovskite light-absorbing layer, or first preparing a buffer layer on the side of the second charge transport layer away from the perovskite light-absorbing layer, and then preparing a transparent electrode and a metal electrode, to obtain the perovskite / crystalline silicon tandem solar cell.

[0076] In step (3), the inorganic skeleton layer refers to a compound comprising an inorganic salt of a divalent inorganic cation, a monovalent inorganic cation and a monovalent anion as the main substance. The divalent inorganic cation includes Pb 2+ , and optionally can further include one or more of Sn 2+ , Cu 2+ , Ge 2+ , etc. The monovalent inorganic cation includes Cs + , and optionally can further include one or more of Li + , Na + , K + , Rb + , etc. The monovalent anion can be selected from one or more of halogen ions, CN - , OCN - , SeCN - , SCN - and BF4 - . For example, the inorganic skeleton layer can include a compound formed by one or more of lead iodide PbI2, lead bromide PbBr2, lead chloride PbCl2, etc. and one or more of cesium iodide CsI, cesium bromide CsBr, cesium chloride CsCl, etc.

[0077] In the present application, the inorganic skeleton layer has a porous morphology. The evaporation method of the inorganic skeleton layer can be co-evaporation. In some embodiments, the inorganic skeleton layer is obtained by co-evaporation of inorganic salts including a lead source and a cesium source. In the present application, the lead source of the inorganic skeleton layer can be selected from one or more of lead iodide, lead bromide and lead chloride, and the cesium source of the inorganic skeleton layer can be selected from one or more of cesium iodide, cesium bromide and cesium chloride.

[0078] The average thickness of the inorganic skeleton layer can be 125-1300 nm, preferably 187.5-812.5 nm.

[0079] In step (3), the organic salt refers to a compound in which monovalent organic cations and monovalent anions are the main substances. The monovalent organic cation can be selected from formamidinium ion, methylamine ion and dimethylamine ion. The monovalent anion can be selected from one or more of halogen ion, CN - , OCN - , SeCN - , SCN - and BF4 - . For example, the organic salt can include one or more of iodomethylformamidinium, bromomethylformamidinium, chloromethylformamidinium, iodomethylamine, bromomethylamine, chloromethylamine, iododimethylamine, bromodimethylamine, chlorodimethylamine, etc.

[0080] In some embodiments, the organic salt includes one or more of iodomethylformamidinium, bromomethylformamidinium, chloromethylformamidinium, iodomethylamine, bromomethylamine and chloromethylamine.

[0081] In the present application, the method of depositing the organic salt can be a solution method, an evaporation method or a sublimation method, and the solution method can be a spin coating method, a slot coating method, a doctor blade coating method, an ultrasonic spray method or an inkjet printing method. In some embodiments, the evaporation method is used to deposit the organic salt.

[0082] In step (3), the annealing temperature can be 80-200℃, for example 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃.

[0083] In step (3), the annealing time can be 1-30 min, for example 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min.

[0084] In some embodiments, in step (5), a buffer layer is first prepared on the electron transport layer, and then a transparent electrode is prepared on the buffer layer.

[0085] In the present application, the perovskite structure material has a chemical formula of ABX3. The A ion comprises cesium ion, and can further comprise one or more selected from methylamine ion (MA + ), formamidinium ion (FA + ), dimethylamine ion and rubidium ion. The B ion comprises lead ion, and can further comprise one or more selected from stannum ion, copper ion, zinc ion, gallium ion and calcium ion. The X ion can be one or more selected from F - , I - , Br - , Cl - , CN - , OCN - , SeCN - , BF4 - and SCN - . In some embodiments, the perovskite structure material has a chemical formula of Cs 0.22 FA 0.8 Pb(I 0.8 Br 0.2 )3.

[0086] The relationship between the average thickness d of the inorganic skeleton layer and the average height h of the relief structure is preferably controlled as d = (0.125-0.325)h. Controlling d and h within the above relationship is beneficial to the design of the conformal morphology of the inorganic skeleton layer, thereby facilitating the reaction of the organic salt layer to generate a higher-quality perovskite thin film. When the average height of the relief structure in step (1) is 1-4 μm, the average thickness of the inorganic skeleton layer in step (3) is preferably controlled as 125-1300 nm. When the average height of the relief structure in step (1) is 1.5-2.5 μm, the average thickness of the inorganic skeleton layer in step (3) is 187.5-812.5 nm.

[0087] In the present application, the relationship between the average thickness D of the perovskite light-absorbing layer and the average height h of the relief structure is controlled as D = (0.25-0.65)h, the molar ratio of Pb 2+ to Cs + is controlled as 2:1-7:1, and the average height of the relief structure is controlled as 1-4 μm. The synergistic effect of the three is beneficial to achieve a porous conformal morphology suitable for reaction with the organic salt, thereby preparing a perovskite / crystalline silicon stacked solar cell assembly with excellent performance and high efficiency.

[0088] The thickness of the hole transport layer of the present application is preferably 1-20 nm, such as 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm.

[0089] The thickness of the electron transport layer of the present application is preferably 1-30 nm, for example 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm.

[0090] The thickness of the buffer layer of the present application is preferably 3-30 nm, for example 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm.

[0091] The thickness of the composite layer of the present application is preferably 2-20 nm, for example 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm.

[0092] The perovskite top cell of the present application can be divided into formal and reverse perovskite solar cells according to the positions of the hole transport layer and the electron transport layer. Specifically, the perovskite / crystalline silicon tandem cell of the present application can be a formal tandem perovskite solar cell or a reverse tandem perovskite solar cell.

[0093] In the present application, the formal tandem perovskite solar cell can sequentially include a bottom cell and a formal perovskite top cell, and the formal perovskite top cell can sequentially include an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a top electrode. In the present application, the reverse tandem perovskite solar cell can sequentially include a bottom cell and a reverse perovskite top cell, and the reverse perovskite top cell can sequentially include a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a top electrode.

[0094] In the present application, the hole transport layer can be nickel oxide (NiOx) and / or a self-assembled material, and the self-assembled material includes but is not limited to one or more of [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [4-(7H-dibenzo-carbazol-7-yl)butyl]phosphonic acid (4PADCB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)benzenamine] (TAPC).

[0095] The electron transport layer of the present application can be one or more selected from TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnOx, SnZnOx, fullerene (e.g. C60 and C70) and fullerene derivative (e.g. PCBM, ICBA). Preferably, the electron transport layer is selected from one or more of fullerene and fullerene derivative, the fullerene is preferably selected from one or both of C60 and C70, and the fullerene derivative is preferably selected from one or both of PCBM and ICBA.

[0096] The top electrode material of the present application can be one or more selected from Au, Ag, Al, Cu, graphene, TCO material and nanocrystalline silicon, and the electrode preparation method can include one or more of spin coating, blade coating, evaporation, printing, spraying, spray pyrolysis and slot coating, and the top electrode of the present application can be a transparent electrode and / or a gate line electrode.

[0097] In some embodiments, the top electrode includes a transparent electrode and a metal electrode. The material of the transparent electrode can be a transparent conductive oxide. The transparent conductive oxide is preferably selected from one or more of indium tin oxide, indium zinc oxide, tungsten-doped indium oxide, cerium-doped indium oxide and aluminum-doped zinc oxide. The material of the metal electrode can be selected from one or more of silver, copper, gold and aluminum.

[0098] In some embodiments, the perovskite top cell includes, in sequence, a hole transport layer, a perovskite light absorbing layer, an electron transport layer, a transparent electrode and a metal electrode, wherein the hole transport layer of the perovskite top cell is adjacent to the crystalline silicon bottom cell.

[0099] In some embodiments, the perovskite top cell further includes a buffer layer between the electron transport layer and the transparent electrode. The material of the buffer layer is preferably selected from one or both of bathocuproine and tin dioxide.

[0100] In some embodiments, the perovskite top cell further includes a composite layer between the hole transport layer and the crystalline silicon bottom cell. The material of the composite layer is preferably selected from one or more of indium tin oxide, indium zinc oxide, tungsten-doped indium oxide, cerium-doped indium oxide and aluminum-doped zinc oxide.

[0101] The present application will be described in detail below with specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present application. The methods, reagents and materials used in the examples are conventional in the art unless otherwise specified. The starting compounds in the examples can be purchased through commercial channels.

[0102] In the examples and comparative examples, the average height of the silicon wafer cell pyramid structure and the average thickness of the perovskite light-absorbing layer are obtained by measuring the height value or thickness value by the method described above and then mathematically processing the value, with two decimal places retained. It can be understood that even for the same batch of silicon wafer cells of the same specification, the average height of the pyramid structure measured in different areas may be slightly different. In the examples and comparative examples, the average height of the pyramid structure has an error of within 1%, and can be considered as the same value, and the error calculation method is: (average height 1-average height 2) / average height 2*100%, wherein average height 1 is greater than or equal to average height 2; the average thickness of the perovskite light-absorbing layer has an error of within 1%, and can be considered as the same value, and the error calculation method is: (average thickness 1-average thickness 2) / average thickness 2*100%, wherein average thickness 1 is greater than or equal to average thickness 2. For example, as shown in Table 1, the average height of the pyramid structure in Examples 1 and 2 is 2.02 μm and 2.01 μm, respectively, which can be considered as the same average height of the pyramid structure in Examples 1 and 2. Similarly, as shown in Table 1, the average thickness of the perovskite light-absorbing layer in Examples 1 and 2 is 800.25 nm and 800.17 nm, respectively, which can be considered as the same average thickness of the perovskite light-absorbing layer in Examples 1 and 2.

[0103] Example 1

[0104] The present embodiment provides a perovskite / silicon stacked solar cell, and the specific preparation method is as follows:

[0105] (1) A silicon wafer cell is selected as a bottom cell, the surface of the silicon wafer cell has a textured structure, the textured structure comprises a plurality of pyramid structures, the average height of the pyramid structure is 2.02 μm, the silicon wafer cell is an HJT cell, and the total thickness of the silicon wafer cell is 150 μm;

[0106] (2) A composite layer is prepared on the surface of the silicon wafer cell having the textured structure: a 10 nm thick IZO composite layer is prepared by sputtering deposition;

[0107] (3) A hole transport layer is prepared: a 0.3 mmol / mL 4-(3,6-dimethyl-9H-carbazole-9-yl) butyl phosphate (Me-4PACz) ethanol solution is prepared, and a hole transport layer with a composition of Me-4PACz and a thickness of 1 nm is prepared on the composite layer by slot coating;

[0108] (4) The perovskite light-absorbing layer is prepared by a two-step method:

[0109] PbI2, CsBr and PbBr2 are co-evaporated on the surface of the hole transport layer by an evaporation method, wherein the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic framework layer with an average thickness of 400.15 nm and a molar ratio of lead element to cesium element of Pb:Cs = 4.5:1;

[0110] An iodofuramide (FAI) is deposited on the surface of the inorganic framework layer by an evaporation method to obtain an organic salt layer with an average thickness of 450.32 nm, and the evaporation rate of the FAI is / s, and the inorganic framework layer and the organic salt layer together constitute a perovskite pre-deposition layer.

[0111] The perovskite pre-deposition layer is subjected to annealing treatment, the annealing environment humidity is 50% RH, the annealing temperature is 170°C, and the annealing time is 40 min, to obtain a perovskite light-absorbing layer with a component of Cs 0.22 FA 0.8 Pb(I 0.8 Br 0.2 )3, an average thickness of 800.25 nm, and a band gap of about 1.68 eV.

[0112] (5) An electron transport layer is prepared: a C 60 is evaporated on the surface of the perovskite by an evaporation method to obtain an electron transport layer with a thickness of 20 nm;

[0113] (6) A buffer layer is prepared: SnO2 with a thickness of 15 nm is deposited on the surface of the electron transport layer as a buffer layer by an atomic layer deposition method;

[0114] (7) A transparent electrode layer is prepared: an IZO transparent conductive thin film with a thickness of 80 nm is deposited on the surface of the buffer layer as a transparent electrode layer by a sputtering deposition method;

[0115] (8) A back electrode is prepared: a metal silver grid line is prepared by a thermal evaporation method, and a perovskite / crystalline silicon stacked solar cell is obtained.

[0116] Example 2

[0117] A solar cell assembly similar to that of Example 1 is prepared in this example, but the difference is that:

[0118] In step (4), when the perovskite layer is prepared by a two-step method, PbI2, CsBr and PbBr2 are co-evaporated on the surface of the hole transport layer by an evaporation method, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic framework layer with an average thickness of 400.17 nm and a molar ratio of lead element to cesium element of Pb:Cs = 5:1.

[0119] Example 3

[0120] The embodiment prepares a solar cell module similar to that of Example 1, but different in that:

[0121] In the two-step method for preparing the perovskite layer in step (4), when co-evaporating PbI2, CsBr and PbBr2 on the surface of the hole transport layer, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic framework layer with an average thickness of 400.23 nm and a molar ratio of lead element to cesium element of Pb:Cs = 4:1.

[0122] Example 4

[0123] The embodiment prepares a solar cell module similar to that of Example 1, but different in that:

[0124] In the textured structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 1.51 μm;

[0125] In step (4), the average thickness of the inorganic framework layer is 350.24 nm, the average thickness of the organic salt layer is 400.31 nm, and the average thickness of the perovskite light-absorbing layer is 700.28 nm.

[0126] Example 5

[0127] The embodiment prepares a solar cell module similar to that of Example 1, but different in that:

[0128] In the textured structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 2.52 μm;

[0129] In step (4), the average thickness of the inorganic framework layer is 500.31 nm, the average thickness of the organic salt layer is 550.28 nm, and the average thickness of the perovskite light-absorbing layer is 950.37 nm.

[0130] Example 6

[0131] The embodiment prepares a solar cell module similar to that of Example 1, but different in that:

[0132] In step (4), the average thickness of the inorganic framework layer is 250.26 nm, the average thickness of the organic salt layer is 300.31 nm, and the average thickness of the perovskite light-absorbing layer is 500.38 nm.

[0133] Example 7

[0134] The embodiment prepares a solar cell module similar to that of Example 1, but different in that:

[0135] In step (4), the average thickness of the inorganic skeleton layer is 650.37 nm, the average thickness of the organic salt layer is 700.28 nm, and the average thickness of the perovskite light-absorbing layer is 1300.39 nm.

[0136] Example 8

[0137] This example prepared a solar cell module similar to that of Example 1, except that:

[0138] In the texturing structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 1.00 μm;

[0139] In step (4), the average thickness of the inorganic skeleton layer is 300.31 nm, the average thickness of the organic salt layer is 350.37 nm, and the average thickness of the perovskite light-absorbing layer is 600.25 nm.

[0140] Example 9

[0141] This example prepared a solar cell module similar to that of Example 1, except that:

[0142] In the texturing structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 4.02 μm;

[0143] In step (4), the average thickness of the inorganic skeleton layer is 700.21 nm, the average thickness of the organic salt layer is 780.32 nm, and the average thickness of the perovskite light-absorbing layer is 1400.38 nm.

[0144] Example 10

[0145] This example prepared a solar cell module similar to that of Example 1, except that:

[0146] In step (4), when the perovskite layer is prepared by a two-step method, when PbI2, CsBr and PbBr2 are co-evaporated on the surface of the hole transport layer by an evaporation method, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic skeleton layer with an average thickness of 400.37 nm and a molar ratio of lead element to cesium element of Pb:Cs = 2:1.

[0147] Example 11

[0148] This example prepared a solar cell module similar to that of Example 1, except that:

[0149] In the two-step method for preparing the perovskite layer, when PbI2, CsBr and PbBr2 are co-evaporated on the surface of the hole transport layer, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, the evaporation rate of PbBr2 is / s, and an inorganic framework layer with an average thickness of 400.23 nm and a molar ratio of lead element to cesium element of Pb:Cs = 7:1 is obtained.

[0150] Example 12

[0151] In this example, a solar cell module similar to that of Example 1 is prepared, except that:

[0152] In the textured structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 1.01 μm.

[0153] In step (4), the average thickness of the inorganic framework layer is 150.13 nm, the average thickness of the organic salt layer is 200.20 nm, and the average thickness of the perovskite light-absorbing layer is 250.23 nm.

[0154] Example 13

[0155] In this example, a solar cell module similar to that of Example 1 is prepared, except that:

[0156] In the textured structure of the crystalline silicon cell used in step (1), the average height of the pyramid structure is 4.02 μm.

[0157] In step (4), the average thickness of the inorganic framework layer is 1300.13 nm, the average thickness of the organic salt layer is 1400.15 nm, and the average thickness of the perovskite light-absorbing layer is 2600.27 nm.

[0158] Comparative Example 1

[0159] The other conditions of this comparative example are the same as those of Example 1, except that:

[0160] In step (4), the average thickness of the inorganic framework layer is 800.32 nm, the average thickness of the organic salt layer is 900.17 nm, and the average thickness of the perovskite light-absorbing layer is 1600.36 nm.

[0161] Comparative Example 2

[0162] The other conditions of this comparative example are the same as those of Example 1, except that:

[0163] In step (4), the average thickness of the inorganic framework layer is 200.19 nm, the average thickness of the organic salt layer is 250.24 nm, and the average thickness of the perovskite light-absorbing layer is 400.38 nm.

[0164] Comparative Example 3

[0165] The other conditions of the present comparative example are the same as those of Example 1, except that:

[0166] In step (4), when the perovskite layer is prepared by a two-step method, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic framework layer having a molar ratio of lead element to cesium element of Pb:Cs = 1.5:1 and an average thickness of 400.32 nm.

[0167] Comparative Example 4

[0168] The other conditions of the present comparative example are the same as those of Example 1, except that:

[0169] In step (4), when the perovskite layer is prepared by a two-step method, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, and the evaporation rate of PbBr2 is / s, to obtain an inorganic framework layer having a molar ratio of lead element to cesium element of Pb:Cs = 8:1 and an average thickness of 400.28 nm.

[0170] Comparative Example 5

[0171] The other conditions of the present comparative example are the same as those of Example 1, except that:

[0172] In step (1), the average height of the pyramid structure in the textured structure of the crystalline silicon cell used is 0.71 μm.

[0173] Comparative Example 6

[0174] The other conditions of the present comparative example are the same as those of Example 1, except that:

[0175] In step (1), the average height of the pyramid structure in the textured structure of the crystalline silicon cell used is 5.03 μm.

[0176] Comparative Example 7

[0177] The other conditions of the present comparative example are the same as those of Example 1, except that:

[0178] In the two-step method for preparing the perovskite layer, when PbI2, CsBr and PbBr2 are co-evaporated on the surface of the hole transport layer, the evaporation rate of PbI2 is / s, the evaporation rate of CsBr is / s, the evaporation rate of PbBr2 is / s, and an inorganic framework layer with a molar ratio of lead element to cesium element of Pb:Cs = 1:1 and an average thickness of 400.39 nm is obtained.

[0179] Some parameters in the preparation process of the examples and comparative examples are shown in Table 1.

[0180] Table 1: Some preparation parameters of examples and comparative examples

[0181]

[0182]

[0183] Test Example

[0184] At 25°C, under AM 1.5G standard solar spectrum, light intensity of 100 mW / cm 2 Using a solar simulator, the voltage range was set to -0.5-2V, and the performance (open-circuit voltage, short-circuit current density, fill factor and photoelectric conversion efficiency) of the solar cell module in the examples and comparative examples was measured, and the specific results are shown in Table 2.

[0185] (1) Open-circuit voltage (Voc): the voltage value corresponding to the current equal to zero.

[0186] (2) Short-circuit current density (Jsc): the current value when the voltage is zero is the short-circuit current (Isc), and the current size on the unit cell surface area is the short-circuit current density.

[0187] (3) Fill factor (FF): the ratio of the maximum output power (Pmax) of the battery to the product of the open-circuit voltage and the short-circuit current, the calculation formula is (Pmax / Voc*Isc), and the maximum power point is the point at which the battery output power reaches the maximum value.

[0188] (4) Photoelectric conversion efficiency (PCE): photoelectric conversion efficiency refers to the ratio of the maximum output power to the incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0189] Table 2: Photovoltaic performance test results of solar cell modules of examples and comparative examples

[0190]

[0191]

[0192] From the experimental results of Table 1, it can be seen that by controlling the Pb:Cs molar ratio in the perovskite inorganic framework layer, the average height of the pyramid structure of the crystalline silicon cell texturing structure, and the ratio of the average thickness of the perovskite light-absorbing layer to the average height of the pyramid structure within the ranges of the present application, a perovskite light-absorbing layer with a conformal morphology can be obtained, and further better device performance can be obtained.

[0193] Specifically, the open-circuit voltage and the photoelectric conversion efficiency of the perovskite crystalline silicon tandem cells of Examples 1-13, in which the average height of the pyramid structure is 1-4 μm, the Pb / Cs molar ratio is 2:1-7:1, and the average thickness D of the perovskite light-absorbing layer to the average height h of the pyramid structure satisfies D=(0.25-0.65)h, are both higher than those of Comparative Examples 1-7 in which at least one of the aforementioned parameters does not meet the requirements.

[0194] Further, by comparing Examples 1, 2, 3, 10, and 11, it can be seen that the perovskite crystalline silicon tandem cells of Examples 1-3 in which the Pb / Cs molar ratio in the inorganic framework layer is controlled within the preferred range of 4:1-5:1 have higher short-circuit current density, fill factor, and photoelectric conversion efficiency than the perovskite crystalline silicon tandem cells of Example 10 in which the Pb / Cs molar ratio is 2:1 and the perovskite crystalline silicon tandem cells of Example 11 in which the Pb / Cs molar ratio is 7:1.

[0195] Figure 4 The electron micrographs of the inorganic framework layers of Comparative Example 4 (Pb:Cs=8:1), Example 11 (Pb:Cs=7:1), Example 2 (Pb:Cs=5:1), Example 3 (Pb:Cs=4:1), Example 10 (Pb:Cs=2:1), and Comparative Example 7 (Pb:Cs=1:1) with different Pb:Cs molar ratios are shown. Figure 4 Of the six inorganic framework layers shown, only the Pb:Cs molar ratio is a variable, and the other parameters are kept constant. It can be seen that when the Pb:Cs molar ratio is 8:1 (Comparative Example 4), the inorganic framework layer is loose and porous and does not have a conformal morphology; when the Pb:Cs molar ratio is 7:1 (Example 11), 5:1 (Example 2), 4:1 (Example 3), or 2:1 (Example 10), the inorganic framework layer is porous and has a conformal morphology; and when the Pb:Cs molar ratio is 1:1 (Comparative Example 7), the inorganic framework layer has a conformal morphology but is dense.

[0196] Figure 5 and Figure 6 The electron micrographs of the perovskite light-absorbing layers of Comparative Example 1 and Comparative Example 2 are shown, respectively. From the electron micrographs of the perovskite light-absorbing layers of Comparative Example 1 and Comparative Example 2, it can be seen that the perovskite light-absorbing layer of Comparative Example 1 has a conformal morphology, but is dense, and the perovskite light-absorbing layer of Comparative Example 2 has a conformal morphology and is porous. Figure 5It can be seen from the above that, since the ratio of the average thickness D of the perovskite light-absorbing layer of Comparative Example 1 to the average height h of the pyramid structure is 0.8, D=(0.25-0.65)h is not satisfied, the perovskite light-absorbing layer is relatively too thick, which causes the perovskite material to accumulate at the bottom of the pyramid, so that the perovskite light-absorbing layer does not have a conformal morphology. Figure 6 It can be seen from the above that, since the ratio of the average thickness D of the perovskite light-absorbing layer of Comparative Example 2 to the average height h of the pyramid structure is 0.2, D=(0.25-0.65)h is not satisfied, the perovskite light-absorbing layer is relatively too thin, which causes the perovskite material to be difficult to uniformly cover on the pyramid structure, so that the perovskite light-absorbing layer does not have a conformal morphology. Figure 7 and Figure 8 The electron micrographs of the perovskite light-absorbing layers of Comparative Example 3 and Comparative Example 7 are given respectively, since the molar ratio of Pb:Cs in the inorganic skeleton layer is less than 2:1, which does not meet the requirements of the present application, causing the inorganic salt layer to be too dense, and the subsequently deposited organic salt layer cannot fully react therewith, the perovskite light-absorbing layer formed at the bottom is not fully reacted, which affects the performance of the device.

Claims

1. A perovskite / crystalline silicon tandem solar cell, characterized in that, The perovskite / crystalline silicon tandem solar cell comprises a crystalline silicon bottom cell and a perovskite top cell; The surface of the crystalline silicon bottom cell near the perovskite top cell has a textured structure, the textured structure including an undulating structure, the average height of the undulating structure being 1-4 μm. The perovskite top solar cell includes a perovskite light-absorbing layer, which comprises a perovskite structural material. The perovskite structural material includes a first cation and a second cation, wherein the first cation comprises an organic cation and Cs. + The second cation contains Pb 2+ Pb in the perovskite light-absorbing layer 2+ With Cs + The molar ratio is 2:1-7:1; The average thickness D of the perovskite light-absorbing layer and the average height h of the undulating structure satisfy the following condition: D = (0.25 ~ 0.65)h.

2. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, Pb in the perovskite light-absorbing layer 2+ With Cs + The molar ratio is 4:1-5:

1.

3. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The average thickness D of the perovskite light-absorbing layer and the average height h of the undulating structure satisfy the following condition: D = (0.4 ~ 0.6)h.

4. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The average height of the undulating structure is 1.5-2.5 μm.

5. The perovskite / crystalline silicon tandem solar cell as described in claim 1 or 4, characterized in that, The average height of the undulating structure is obtained by a method including the following steps: in the cross-sectional electron microscope image of the crystalline silicon bottom cell, at least two regions with a textured structure width of 20 μm are selected, and the height of each undulating structure in each selected region is counted and the average value is taken.

6. The perovskite / crystalline silicon tandem solar cell as described in claim 5, characterized in that, If the average height of the undulating structure is measured in at least 10 selected areas, and the average height of the undulating structure in more than 80% of the selected areas falls within the range of 1-4 μm or 1.5-2.5 μm, then the average height of the undulating structure is considered to be within the range of 1-4 μm or 1.5-2.5 μm.

7. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The average thickness of the perovskite light-absorbing layer is obtained by a method including the following steps: in the cross-sectional electron microscope image of the perovskite / crystalline silicon tandem solar cell, at least two regions with a textured structure width of 20 μm are selected, and the maximum and minimum thicknesses of the perovskite light-absorbing layer on each undulating structure in each selected region are counted, and the average value is taken.

8. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The undulating structure includes one or both of the following: a pyramid structure and a wave-shaped structure.

9. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The organic cation is selected from one or more of formamidinium ions, methylamine ions, and dimethylamine ions.

10. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The perovskite light-absorbing layer has a shape-preserving morphology.

11. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The maximum thickness of the perovskite light-absorbing layer on any undulating structure is D1 and the minimum thickness is D2, satisfying D2≥0.6D1.

12. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The perovskite structural material also includes anions, which are selected from halide ions, CN ions, etc. - OCN - SeCN - SCN - and BF4 - One or more of them.

13. The perovskite / crystalline silicon tandem solar cell as described in claim 1, characterized in that, The halide ion is selected from one or more of fluoride ions, chloride ions, bromide ions, and iodide ions.

14. A solar cell module, characterized in that, The solar cell module includes any one of claims 1-13 perovskite / crystalline silicon tandem solar cells.

15. A method for preparing a perovskite / crystalline silicon tandem solar cell according to any one of claims 1-13, characterized in that, The method includes: (1) A crystalline silicon cell with a textured surface is used as the bottom cell, wherein the textured surface includes an undulating structure; (2) A charge transport layer is prepared above the surface of the bottom battery with a textured surface; (3) An inorganic framework layer is prepared above the charge transport layer by evaporation, an organic salt is deposited on the inorganic framework layer, and a perovskite light-absorbing layer is obtained by annealing.

16. The method as described in claim 15, characterized in that, In step (3), the evaporation method of the inorganic framework layer is co-evaporation.

17. The method as described in claim 15, characterized in that, In step (3), the organic salt is deposited by solution method, evaporation method or sublimation method. The solution method includes one or more of spin coating method, slot coating method, blade coating method, ultrasonic spraying method and inkjet printing method.

18. The method as described in claim 15, characterized in that, In step (3), the organic salt is deposited by evaporation.

19. The method as described in claim 15, characterized in that, In step (3), the annealing temperature is 80-200℃ and the annealing time is 1-30min.

20. The method as described in claim 15, characterized in that, Step (2) includes: firstly, preparing a composite layer on the surface of the bottom battery with a textured structure, and then preparing a charge transport layer on the surface of the composite layer.

21. The method as described in claim 15, characterized in that, In step (2), the charge transport layer is a hole transport layer.

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