An all-inorganic silicon-based perovskite solar tandem cell and its preparation method

Abstract

This invention discloses an all-inorganic silicon-based perovskite tandem solar cell and its fabrication method. The fabrication method includes: providing a heterojunction crystalline silicon substrate with a micro-pyramid structure for the light-absorbing surface; fabricating a hole transport layer on the light-absorbing surface of the heterojunction crystalline silicon substrate; coating the hole transport layer with a perovskite precursor solution, wherein the solute in the perovskite precursor solution includes an inorganic salt and an organic ammonium salt, which is used to form an all-inorganic perovskite light-absorbing layer by annealing; the solvent includes a main solvent and a coordination solvent; and sequentially fabricating an electron transport layer and an electrode on the all-inorganic perovskite light-absorbing layer. This invention, through a one-step solution method, introduces organic ammonium salts and coordination solvents into the all-inorganic perovskite precursor solution, significantly delaying the crystallization kinetics of CsPbI3. The resulting film has a uniform and dense morphology, achieving complete coverage of the rough textured heterojunction substrate, thereby fabricating a high-efficiency all-inorganic silicon-based perovskite tandem solar cell.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic devices and photovoltaic materials, specifically relating to an all-inorganic silicon-based perovskite solar tandem cell and its preparation method. Background Technology

[0002] In silicon-based perovskite tandem solar cells, a suitable wide-bandgap perovskite (bandgap between 1.65 and 1.70 eV) is needed for current matching between the silicon bottom and top cells, serving as the absorber layer for the top cell. To date, mixed-cation-mixed-halide hybrid perovskites have been widely used as the light-absorbing layer for the top cell, and the efficiency of this tandem cell structure has been recognized. However, its practical application is limited by unstable organic components and phase separation of halides under illumination or bias conditions, which restricts the operational reliability of silicon-based perovskite tandem solar cells.

[0003] CsPbI3 inorganic perovskite, with its ideal bandgap of ~1.70 eV and thermodynamic stability, and the absence of organic components and mixed halogens, is a competitive top-cell light-absorbing material for silicon-based perovskite tandem solar cells. However, realizing this prospect in a tandem structure remains challenging due to the difficulty of uniformly depositing CsPbI3 on ​​textured silicon heterojunction (SHJ) cells. Ammonium salts are widely used in existing technologies to improve device stability and efficiency.

[0004] For example, Reference 1 (Unveiling property of hydrolysis-derived DMAPbI3 forperovskite devices: composition engineering, defect mitigation, and stabilityoptimization, iScience (2019, 15, 165-172) The use of dimethylammonium hydroiodide (DMAI) additive can stabilize black phase CsPbI3, but it will slow down crystallization kinetics, resulting in delayed nucleation and growth of CsPbI3, which in turn causes problems such as uneven grain size, incomplete film coverage and interfacial voids.

[0005] For example, to ensure sufficient light transmittance without sacrificing conversion efficiency, the invention patent with publication number CN119744065A discloses a heterojunction perovskite tandem solar cell and a method for preparing the perovskite tandem solar cell, including: providing a crystalline silicon substrate, the crystalline silicon substrate including a front side and a back side; sequentially stacking an initial functional film layer and a metal halide film on the front side of the initial crystalline silicon substrate; spin-coating an organic ammonium salt solution onto the surface of the metal halide film to form an initial perovskite light-absorbing layer, wherein the solute of the organic ammonium salt solution includes an organic ammonium salt, and the solvent includes a first solvent and a second solvent in a set ratio, the polarity of the second solvent being greater than that of the first solvent, such that at least a portion of the metal halide film dissolves in the second solvent to form metal halide particles, the metal halide particles reacting with the organic ammonium salt solution to form perovskite microcrystal particles; annealing the initial perovskite light-absorbing layer to obtain the perovskite light-absorbing layer; and stacking multiple functional film layers on the perovskite light-absorbing layer to prepare the perovskite tandem solar cell. However, this scheme uses organic-inorganic hybrid perovskite (containing FA). + MA + Organic cations (such as organic cations) are prone to volatilization of organic components and separation of halide phases under actual light, humidity, heat and bias conditions, resulting in poor long-term reliability of the device and difficulty in meeting the stability requirements of industrialization.

[0006] Therefore, seeking an all-inorganic perovskite fabrication process compatible with industrial-grade textured silicon substrate solar cells will help realize high-efficiency silicon-based perovskite solar tandem cells and promote the industrialization of perovskite or silicon tandem devices. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, such as poor stability, complex processes, and insufficient controllability of crystallization in hybrid perovskite tandem solar cells, and the challenges faced by high-quality deposition of all-inorganic CsPbI3 on ​​textured silicon substrate solar cells (due to its rapid crystallization rate, low nucleation density, and tendency to form discontinuous, pinhole-filled films that cannot completely cover the micropyramidal structure), this invention provides an all-inorganic silicon-based perovskite solar tandem solar cell and its preparation method. This method forms a dense, pinhole-free, and completely textured black-phase all-inorganic perovskite film, thereby producing a high-efficiency all-inorganic silicon-based perovskite tandem solar cell.

[0008] A method for fabricating an all-inorganic silicon-based perovskite solar tandem cell includes the following steps: A heterogeneous crystalline silicon bottom cell with a micro-pyramid structure for the light-absorbing surface is provided; A hole transport layer is prepared on the light-absorbing surface of a heterocrystalline silicon substrate solar cell; A perovskite precursor solution is coated onto a hole transport layer. The solutes in the perovskite precursor solution include inorganic salts and organic ammonium salts, which are used to form an all-inorganic perovskite light-absorbing layer by annealing. The solvent includes a main solvent and a coordination solvent. An electron transport layer and an electrode were sequentially fabricated on an all-inorganic perovskite light-absorbing layer.

[0009] This invention introduces an organic ammonium salt and a coordination solvent into an all-inorganic perovskite precursor solution via a one-step solution method, utilizing the interaction between the coordination solvent and Pb. 2+ The strong coordination effect of the precursors forms a stable solvation intermediate, which facilitates the transformation of the uniformly distributed inorganic and organic salt intermediate phases into black CsPbI3 perovskite during the annealing process. This significantly slows down the crystallization kinetics of CsPbI3, allowing the precursor solution sufficient time to spread, wet, and penetrate to the valleys on the pyramid surface during spin coating and initial annealing, thus achieving complete conformal coverage without pinholes or interfacial voids. Studies have shown that the CsPbI3 films prepared by this method have a uniform and dense morphology, achieving complete coverage of rough textured heterojunction bottom solar cells.

[0010] Furthermore, the volatile organic ammonium salt used in this invention completely volatilizes during the annealing process, leaving no residue in the final perovskite lattice, resulting in a pure, entirely inorganic CsPbI3 black phase. From an intrinsic material perspective, CsPbI3 contains no volatile organic components and does not rely on mixed halogens to achieve the ideal band gap. Therefore, it fundamentally avoids the degradation of organic components and halide segregation, resulting in significantly better long-term operational reliability of the device compared to hybrid systems.

[0011] Preferably, the preparation method further includes: preparing a hole transport layer after preparing a first intermediate layer; preparing an electron transport layer after preparing a second intermediate layer; and preparing an electrode after preparing a third intermediate layer. The first intermediate layer is selected from one or more of the following: tunneling knot, modification material layer, and buffer layer; The second intermediate layer is selected from one or more of the modification material layer and the buffer layer; The third intermediate layer is selected from one or more of the following: the decorative material layer and the buffer layer.

[0012] More preferably, the first intermediate layer is an ITO tunneling junction; the second intermediate layer is an organic amine hydrochloride; and the third intermediate layer is a SnO2 buffer layer.

[0013] Preferably, the hole transport is selected from nickel oxide (NiO). x One or more of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz); The electron transport layer is a fullerene or its derivative; The electrodes are sequentially deposited transparent electrodes and metal electrodes.

[0014] More preferably, the transparent electrode is zinc-doped indium oxide (IZO), and the metal electrode is a silver electrode.

[0015] Preferably, the organic ammonium salt is methylamine hydroiodide (MAI); The molar ratio of organic ammonium salt to inorganic salt is: x :1, 0.8≤ x ≤1.5.

[0016] The above-mentioned organic ammonium salts are selected so that they can completely volatilize during subsequent annealing, ensuring complete conversion of inorganic salts.

[0017] More preferably, the inorganic salt is a mixture of PbI2 and CsI, with a molar ratio of 1:1.

[0018] Preferably, the main solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and 1,4-butyrolactone; The coordination solvent is N-methylpyrrolidone.

[0019] This invention differs from traditional mixed solvents in that the selected main solvent is a good solvent for the CsPbI3 precursor, which coordinates with Pb via Lewis acid-base coordination. 2+ Interactions; the introduced coordinating solvent has high coordination ability and interacts with Pb. 2+ The formation of stable adducts actively regulates crystallization kinetics, transforming rapid, uncontrollable crystallization into gradual, controllable crystallization. This allows the precursor solution sufficient time to fully wet the entire surface of the pyramid, including its steep sidewalls and deep valleys, under the combined effects of gravity, surface tension, and spin-coating centrifugal force. As the coordination solvent gradually evaporates, Pb... 2+ Only then can the CsPbI3 grains be transformed synchronously and uniformly in all parts of the pyramid, thus achieving complete conformal coverage.

[0020] More preferably, the volume ratio of the main solvent to the total volume of the coordinating solvent is 80% to 96%.

[0021] More preferably, the main solvent accounts for 93% of the volume.

[0022] Preferably, the concentration of the perovskite precursor solution in the step is 0.7~2.0 mol L. -1 .

[0023] Preferably, the all-inorganic perovskite light-absorbing layer is a black phase CsPbI3 with a band gap of 1.68~1.73 eV and a thickness of 400~600 nm.

[0024] Preferably, the coating method is one or more of spin coating, spray coating, or slot coating.

[0025] More preferably, the coating is applied using a spin coating process with a spin coating speed of 3000 rpm and a time of 30 s, and the spin coating is carried out in a dry air environment with a relative humidity of less than 10%.

[0026] Preferably, the annealing temperature is 130°C to 170°C, and the annealing time is 10 to 50 min.

[0027] On the other hand, the present invention also provides an all-inorganic silicon-based perovskite solar tandem cell prepared by the above-described preparation method.

[0028] This invention introduces volatile organic ammonium salts and coordination solvents into the perovskite precursor solution. The coordination solvent connects the organic and inorganic salts through hydrogen bonding and chemical coordination, slowing down crystallization kinetics and ensuring uniform distribution and interpenetration of inorganic and volatile organic salts in the mesophase wet film. The volatile organic ammonium salts completely volatilize during annealing and do not remain in the final film, but they play a role in regulating the mesophase and promoting uniform nucleation. This allows for the preparation of all-inorganic silicon-based perovskite tandem solar cells at a mild annealing temperature, solving the problems of organic component volatilization and halide phase segregation in hybrid perovskite-silicon tandem solar cells. This results in highly efficient all-inorganic silicon-based perovskite tandem solar cells with an energy conversion efficiency exceeding 30%.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention introduces a strong coordination solvent, N-methyl-pyrrolidone, and utilizes its interaction with Pb 2+ The formation of stable adducts significantly slows down the crystallization rate, allowing the precursor solution ample time to spread, wet, and penetrate to the valleys on the pyramid surface during spin coating and initial annealing. The resulting CsPbI3 film achieves complete conformal coverage on a rough, textured silicon substrate, free of pinholes and interfacial voids, thus solving the deposition challenge of all-inorganic perovskites on rough, textured surfaces.

[0030] (2) By synergistic regulation of volatile organic ammonium salts and coordination solvents, this invention completely avoids the risks of organic component degradation and halide segregation from the intrinsic nature of the material. Experimental results show that the energy conversion efficiency can reach more than 30%.

[0031] (3) The present invention adopts a one-step solution method, and high-quality all-inorganic perovskite thin film is obtained by spin coating and annealing once, which simplifies the process, reduces costs, and is conducive to industrialization. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the all-inorganic silicon-based perovskite tandem solar cell described in this invention.

[0033] Figure 2 The image shows the X-ray diffraction pattern of the thin film B obtained in Example 1.

[0034] Figure 3 This is a scanning electron microscope (SEM) image of the surface of thin film B obtained in Example 1.

[0035] Figure 4 This is a cross-sectional scanning electron microscope image of the thin film B obtained in Example 1.

[0036] Figure 5 The JV curve is shown for the stacked device C obtained in Example 1.

[0037] Figure 6 The image shows a scanning electron microscope (SEM) image of the surface of the thin film D obtained in Example 2.

[0038] Figure 7 This is a scanning electron microscope (SEM) image of the surface of the thin film E obtained in Example 3.

[0039] Figure 8 The image shown is a scanning electron microscope (SEM) image of the surface of the thin film F obtained in Example 4.

[0040] Figure 9 The image shows the X-ray diffraction pattern of the thin film G obtained in Comparative Example 1.

[0041] Figure 10 The image shows a scanning electron microscope (SEM) image of the surface of the thin film G obtained in Comparative Example 1.

[0042] Figure 11 This is a cross-sectional scanning electron microscope image of the thin film G obtained in Comparative Example 1.

[0043] Figure 12 The image shows the X-ray diffraction pattern of the thin film H obtained in Comparative Example 2.

[0044] Figure 13 This is a scanning electron microscope image of the surface of the thin film H obtained in Comparative Example 2.

[0045] Figure 14 This is a cross-sectional scanning electron microscope image of the thin film H obtained in Comparative Example 2.

[0046] Figure 15 The image shows the X-ray diffraction pattern of thin film I obtained in Comparative Example 3.

[0047] Figure 16 The image shows the X-ray diffraction pattern of the thin film J obtained in Comparative Example 4.

[0048] Figure 17 The image shows the X-ray diffraction pattern of the thin film K obtained in Comparative Example 5.

[0049] Figure 18 The image shows the X-ray diffraction pattern of the thin film L obtained in Comparative Example 6.

[0050] Figure 19 This is a scanning electron microscope image of the surface of the thin film L obtained in Comparative Example 6.

[0051] Figure 20 The JV curve is shown for the stacked device M obtained in Comparative Example 6. Detailed Implementation

[0052] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention.

[0053] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0054] The power conversion efficiency (PCE) of solar cells used in this article refers to the percentage of power converted from absorbed light into electrical energy. The PCE of a solar cell can be calculated by dividing the maximum power by the incident light irradiance and the surface area of ​​the solar cell under standard test conditions. Standard test conditions typically refer to a temperature of 25°C and an irradiance of 1000 W / m². 2 The spectrum of standard large-scale AM1.5G.

[0055] Example 1 In this embodiment, methylamine hydroiodide (MAI) and N-methylpyrrolidone (NMP) are introduced into the precursor solution of CsPbI3 all-inorganic perovskite, thereby obtaining a high-quality all-inorganic perovskite thin film at a relatively low annealing temperature. Based on this, an all-inorganic silicon-based perovskite tandem solar cell is prepared. The specific process is as follows: 1. Fabrication of all-inorganic silicon-based perovskite tandem solar cells Obtaining S01 silicon heterojunction (SHJ) bottom cells The SHJ bottom cell was purchased. The light-absorbing surface is textured, with a micro pyramid structure and a 15 nm ITO tunnel junction. The bottom cell was used after the light-absorbing surface was treated with ultraviolet ozone for 20 min.

[0056] SO2, Preparation of the hole transport layer (1) ~15 nm NiO was sputtered and deposited on the ITO tunnel junction surface of the light-absorbing surface of the SHJ bottom cell. x Hole transport layer, magnetron sputtering power of 90 W, working pressure of 0.3 Pa, argon flow rate of 100 sccm, deposition time of 500 s.

[0057] (2) Prepare a 0.7 mg / mL isopropanol solution of MeO-2PACz.

[0058] (3) Spin-coating the MeO-2PACz solution onto NiO x The surface was spin-coated at a rate of 5000 rpm for 30 s.

[0059] (4) Anneal MeO-2PACz at 100°C for 10 min to obtain NiO. x / MeO-2PACz composite hole transport layer.

[0060] Preparation of S03 and perovskite light-absorbing layer (1) 368.8 mg PbI2, 207.8 mg CsI, 127.2 mg MAI, and 77.2 μL NMP were dissolved in 1 mL of N,N-dimethylformamide (DMF) to obtain perovskite precursor solution A; the molar ratio of PbI2, CsI, MAI, and NMP was 1:1:1:1, and the amount of each solute or coordinating solvent was 0.8 mmol. The volume ratio of the main solvent was 93%.

[0061] (2) Spin-coating perovskite precursor solution A onto SHJ / NiO x The / MeO-2PACz surface was spin-coated at 3000 rpm for 30 s. The wet film after spin-coating was then heated on a hot plate at 160°C for 20 min to obtain silicon-based all-inorganic perovskite thin film B.

[0062] S04, Preparation of the Modification Layer (1) Preparation of modified layer solution: In this example, 3,5-bis(trifluoromethyl)benzylamine hydrochloride (bCF3-PMACl) and 4-fluorophenylethylamine hydrochloride (4F-PEACl) were used as examples to prepare solutions with a concentration of 5 mmol / L. -1 An isopropanol solution.

[0063] (2) The bCF3-PMACl and 4F-PEACl solutions were spin-coated onto silicon-based inorganic perovskite film B at a spin speed of 4000 rpm for 30 s, and then annealed on a hot plate at 100°C for 5 min.

[0064] S05, Fabrication of the electron transport layer C was evaporated using a physical vapor deposition device. 60 The material deposited a 20 nm electron transport layer on the surface of the modified layer at a deposition rate of 0.2 Å / s.

[0065] S06, Preparation of the buffer layer: A 20 nm thick SnO2 buffer layer was prepared using an atomic layer deposition (ALD) apparatus, with tetramethylaminotin and deionized water as the deposition source.

[0066] S07, Preparation of transparent electrodes Using a magnetron sputtering apparatus, 40 nm of IZO was sputtered onto SnO2 as a transparent electrode.

[0067] S08, Preparation of Metal Electrodes A 500 nm silver grid line was deposited as electrodes on both the positive and negative electrodes of the multilayer device using thermal evaporation, with a deposition rate of 0.2–1 Å / s. -1 The resulting stacked device C is shown in the schematic diagram below. Figure 1 As shown.

[0068] 2. Performance Characterization of All-Inorganic Silicon-Based Perovskite Thin Films and Tandem Solar Cells Figure 2 The image shows the X-ray diffraction (XRD) pattern of the silicon-based all-inorganic perovskite film B in Example 1, which shows that the CsPbI3 perovskite in Example 1 has good crystallinity.

[0069] Figure 3 The image shows a scanning electron microscope (SEM) image of the silicon-based all-inorganic perovskite thin film B in Example 1. It can be seen that the CsPbI3 perovskite thin film in Example 1 has a dense morphology, with no pinholes between grains, and completely covers the SHJ bottom cell.

[0070] Figure 4 The image shows a cross-sectional SEM image of the silicon-based all-inorganic perovskite film B in Example 1. It can be seen that the perovskite film obtained in Example 1 has good contact with the SHJ bottom cell interface, and the micro pyramid structure of the SHJ light-absorbing surface is completely covered by the CsPbI3 perovskite film, which provides a basis for the fabrication of high-efficiency stacked devices.

[0071] Figure 5 The JV curve of the stacked device C obtained in Example 1 has a PCE of 30.3%.

[0072] Example 2 The preparation process of Example 2 is the same as that of Example 1, except that the volume ratio of the main solvent DMF in the total volume of the main solvent and the coordination solvent is 80%.

[0073] Figure 6 The image shows a surface SEM image of the silicon-based all-inorganic perovskite film D in Example 2. The results show that a continuous and completely covered all-inorganic perovskite film can still be formed.

[0074] Example 3 The preparation process of Example 3 is the same as that of Example 1, except that the volume ratio of the main solvent DMF in the total volume of the main solvent and the coordination solvent is 96%.

[0075] Figure 7The image shows a surface SEM image of the silicon-based all-inorganic perovskite film E in Example 3. The results indicate that a completely covered all-inorganic perovskite film can still be formed, but the NMP volume fraction is low, resulting in pits on the perovskite film surface. When the NMP content is too low, it will lead to the formation of numerous surface pits.

[0076] Example 4 The preparation process in this embodiment is the same as in Example 1, except that the molar ratio of MAI to PbI2 is 1.5:1.

[0077] Figure 8 The image shows a surface SEM image of the silicon-based all-inorganic perovskite film F in Example 4. The results show that a continuous and completely covered all-inorganic perovskite film can still be formed.

[0078] Comparative Example 1 The preparation process of this comparative example is the same as that of Example 1, except that the organic ammonium salt in the perovskite precursor solution in step S03 is dimethylamine hydroiodate (DMAI), and no NMP coordination solvent is added.

[0079] The XRD pattern of the silicon-based perovskite thin film G obtained in Comparative Example 1 is shown in Figure 1. Figure 9 Although this method can obtain melanistic perovskite, Figures 10-11 SEM images show that the perovskite film in Comparative Example 1 cannot completely cover the micropyramid structure on the light-absorbing surface of the SHJ bottom cell. Partial exposure of the pyramid structure will cause a short circuit in the top cell, thus preventing the successful fabrication of the tandem cell.

[0080] Comparative Example 2 The preparation process of this comparative example is the same as that of Example 1, except that NMP coordination solvent was not added to the perovskite precursor solution in step S03.

[0081] The XRD pattern of the perovskite thin film H obtained in Comparative Example 2 is shown in Figure 2. Figure 12 This method can also obtain black-phase perovskite, but... Figures 13-14 SEM images show that the surface of the CsPbI3 perovskite film in Comparative Example 2 has a large number of pinholes, and there are voids at the interface between the CsPbI3 layer and the SHJ bottom cell, which will cause serious leakage current and efficiency loss.

[0082] Comparative Example 3 The preparation process of this comparative example is the same as that of Example 1, except that MAI is not added to the perovskite precursor solution (only PbI2 and CsI, molar ratio 1:1), and the volume ratio of the main solvent is still 93%.

[0083] The XRD pattern of thin film I obtained in Comparative Example 3 is shown in Figure 3. Figure 15 The spectrum does not contain the characteristic diffraction peaks of black phase CsPbI3, therefore this method cannot obtain pure black phase CsPbI3.

[0084] Comparative Example 4 The preparation process of this comparative example is the same as that of Example 1, except that the solvent is only the main solvent DMF (without NMP) and no MAI is added (only PbI2 and CsI, molar ratio 1:1).

[0085] The XRD pattern of thin film J obtained in Comparative Example 4 is shown in Figure 4. Figure 16 The spectrum does not contain the characteristic diffraction peaks of black phase CsPbI3, therefore this method cannot obtain pure black phase CsPbI3.

[0086] Comparative Example 5 The preparation process of this comparative example is the same as that of Example 1, except that the volume ratio of the main solvent DMF is changed to 70%.

[0087] The XRD pattern of the thin film K obtained in Comparative Example 4 is shown in Figure 4. Figure 17 Although the spectrum shows characteristic diffraction peaks of black phase CsPbI3, the intensity is low, so this method cannot obtain high-quality pure black phase CsPbI3.

[0088] Comparative Example 6 The preparation process of this comparative example is the same as that of Example 1, except that a polished flat silicon wafer (without texture) is used as the substrate for the bottom cell, and everything else is exactly the same.

[0089] The XRD pattern of the thin film L obtained in Comparative Example 6 is shown in Figure 6. Figure 18 The spectral analysis shows that this method can obtain high-quality CsPbI3 films. Surface SEM images are shown below. Figure 19 The results showed that this method can also form dense CsPbI3 films. Figure 20 The JV curve of the stacked device M obtained in Comparative Example 6 shows that the device efficiency is lower than that of Example 1 due to the decrease in light absorption (increased reflection) and the decrease in short-circuit current. Its PCE is 29.60%.

[0090] In summary, this invention introduces an organic ammonium salt and a coordination solvent into an all-inorganic perovskite precursor solution via a one-step solution method, utilizing the interaction between the coordination solvent and Pb. 2+The strong coordination effect of the micro-pyramid structure forms a stable solvation intermediate, enabling the uniformly distributed inorganic and organic salt intermediate phases to transform into black-phase CsPbI3 perovskite during the annealing process. This significantly slows down the crystallization kinetics of CsPbI3, allowing the precursor solution sufficient time to spread, wet, and penetrate to the valleys on the pyramid surface during spin coating and initial annealing, thus achieving complete conformal coverage without pinholes or interface voids. Studies show that the CsPbI3 films prepared by this method have a uniform and dense morphology, achieving complete coverage of rough textured heterojunction substrates. This indicates that the invention can also be implemented on planar substrates, but the light-trapping effect of the "micro-pyramid structure" is a necessary condition for achieving high efficiency. This invention solves the problem of preparing high-quality CsPbI3 perovskite films on textured silicon substrates, enabling the fabrication of high-efficiency all-inorganic silicon-based perovskite solar cells.

[0091] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an all-inorganic silicon-based perovskite solar tandem cell, characterized in that, Includes the following steps: A heterogeneous crystalline silicon bottom cell with a micro-pyramid structure for the light-absorbing surface is provided; A hole transport layer is prepared on the light-absorbing surface of a heterocrystalline silicon substrate solar cell; A perovskite precursor solution is coated onto a hole transport layer. The solutes in the perovskite precursor solution include inorganic salts and organic ammonium salts, which are used to form an all-inorganic perovskite light-absorbing layer by annealing. The solvent includes a main solvent and a coordination solvent. An electron transport layer and an electrode were sequentially fabricated on an all-inorganic perovskite light-absorbing layer.

2. The preparation method according to claim 1, characterized in that, The organic ammonium salt is selected from methylamine hydroiodate.

3. The preparation method according to claim 1, characterized in that, The molar ratio of organic ammonium salt to inorganic salt is 0.8:1 to 1.5:

1.

4. The preparation method according to claim 1, characterized in that, The main solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, and 1,4-butyrolactone; The coordination solvent is N-methylpyrrolidone.

5. The preparation method according to claim 4, characterized in that, In the total volume of the main solvent and the coordinating solvent, the main solvent accounts for 80% to 96% of the volume.

6. The preparation method according to claim 1, characterized in that, The aforementioned all-inorganic perovskite light-absorbing layer is a black phase CsPbI3 with a band gap of 1.68~1.73 eV and a thickness of 400~600 nm.

7. The preparation method according to claim 6, characterized in that, The annealing temperature is 130°C to 180°C, and the annealing time is 10 to 90 minutes.

8. The preparation method according to claim 1, characterized in that, The preparation method further includes: preparing a hole transport layer after preparing a first intermediate layer; preparing an electron transport layer after preparing a second intermediate layer; and preparing an electrode after preparing a third intermediate layer. The first intermediate layer is selected from one or more of the following: tunneling knot, modification material layer, and buffer layer; The second intermediate layer is selected from one or more of the modification material layer and the buffer layer; The third intermediate layer is selected from one or more of the following: the decorative material layer and the buffer layer.

9. The preparation method according to claim 1, characterized in that, The hole transport is selected from one or more of nickel oxide and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid; The electron transport layer is a fullerene or its derivative; The electrodes are sequentially deposited transparent electrodes and metal electrodes.

10. The all-inorganic silicon-based perovskite solar tandem cell prepared by the preparation method according to any one of claims 1-9.

Images