A perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, its fabrication method and application

Abstract

This invention relates to a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, its fabrication method, and its application. The perovskite solar cell comprises, from bottom to top, a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light-absorbing layer, an electron transport layer, a cathode modification layer, and a top electrode. The modification layer is obtained by using passivation molecules, which are nitrogen heterocyclic derivatives containing cyano and amino functional groups. Compared with existing technologies, this invention, based on this modification layer, can simultaneously optimize the defects of both the perovskite layer and the hole transport layer, effectively solving the energy level mismatch problem between the perovskite layer and the charge transport layer, achieving energy level optimization, and thus improving device performance. Furthermore, the perovskite / silicon tandem solar cell fabricated based on this invention exhibits excellent long-term operational stability.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic solar energy materials technology, and in particular to a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, its preparation method and application. Background Technology

[0002] Perovskite solar cells (PSCs) have become a research hotspot in the photovoltaic field due to their advantages such as high absorption coefficient, long carrier diffusion length, tunable bandgap, and solution processability. Currently, the photoelectric conversion efficiency (PCE) of single-junction perovskite cells has exceeded 27%, and the efficiency of perovskite / silicon tandem cells has reached 34.6%. In high-efficiency tandem devices, wide-bandgap (WBG, 1.65~1.70 eV) perovskite is often used as the top cell; however, its fabrication process faces many bottlenecks, restricting further improvements in device performance and commercial applications.

[0003] First, to obtain wide bandgap characteristics, it is usually necessary to introduce Br. - Replace part I - However, high Br content (>20%) leads to excessively rapid crystallization, forming fine grains and increasing the density of defects in the bulk and at the interface. Even with a trihalomethane strategy to reduce the Br content to below 15%, the defects and energy level mismatch between the perovskite and hole transport layers remain unresolved. Furthermore, the perovskite film surface itself contains defect states, and there is an energy level mismatch between the perovskite active layer and the charge transport layer. These issues induce carrier recombination (especially non-radiative recombination), significantly limiting the improvement of device optoelectronic performance and long-term operational stability.

[0004] Current mainstream solutions to the aforementioned problems include bulk passivation engineering, interface passivation engineering, and the fabrication of novel transport layers. Among these, interface passivation engineering has become a core strategy due to its significant effects and wide applicability, with its core application being the interface modification of hole transport layers (HTLs) / perovskite layers. However, in existing technologies, traditional passivating agents (such as SAM molecules) suffer from problems such as incomplete coverage and molecular aggregation, making it difficult to simultaneously achieve defect passivation and energy level optimization. This fails to meet the demand for high-performance passivation strategies in wide-bandgap perovskite devices. Developing doping / passivation strategies that combine efficient passivation, energy level modulation, and enhanced stability has become crucial for overcoming the performance bottleneck of WBG perovskite devices. Summary of the Invention

[0005] The purpose of this invention is to provide a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, its preparation method and application, which can simultaneously optimize the defects of the perovskite layer and the hole transport layer, effectively solve the energy level mismatch problem between the perovskite layer and the charge transport layer, and achieve energy level optimization.

[0006] The objective of this invention can be achieved through the following technical solutions: One objective of this invention is to provide a perovskite solar cell based on interface modification of nitrogen heterocyclic derivatives, comprising, from bottom to top, a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, a cathode modification layer, and a top electrode, wherein the modification layer is obtained by using passivation molecules, and the passivation molecules are nitrogen heterocyclic derivatives containing cyano and amino functional groups.

[0007] Preferably, the passivating molecule is selected from any one of the following nitrogen heterocyclic derivatives: 3-amino-2-cyanopyridine (Chemical Formula 1), 5-amino-2-cyanopyridine (Chemical Formula 2), 5,6-diamino-2-cyanopyridine (Chemical Formula 3), 5-amino-2,3-dicyanopyridine (Chemical Formula 4), 5,6-diamino-2,3-dicyanopyridine (Chemical Formula 5), ​​3-amino-2-cyanopyrazine (Chemical Formula 6), 5-amino-2-cyanopyrazine (Chemical Formula 7), 5-amino-2,3-dicyanopyrazine (Chemical Formula 8), 3,6-diamino-2,5-dicyanopyrazine (Chemical Formula 9), and 5,6-diamino-2,3-dicyanopyrazine (Chemical Formula 10).

[0008] More preferably, the chemical structural formulas of the passivation molecules described above are as follows: .

[0009] Preferably, the hole transport layer comprises nickel oxide (NiO). x It includes any one or more of the following: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphoric acid (Ph-4PACz).

[0010] More preferably, the hole transport layer is NiO. x / Ph-4PACz composite layer.

[0011] More preferably, the NiO x In the / Ph-4PACz composite layer, NiO x The thickness of the layer is 12~18 nm, and the thickness of the Ph-4PACz layer is 3~7 nm.

[0012] More preferably, the NiO x In the / Ph-4PACz composite layer, NiO x The thickness of the layer is 15 nm, and the thickness of the Ph-4PACz layer is 5 nm.

[0013] Preferably, the perovskite light-absorbing layer is a trihalomethane wide-bandgap perovskite, and also contains Cl.- ,Br - I - Three types of halide ions.

[0014] More preferably, the Br content in the trihalomethane wide-bandgap perovskite is ≤15%.

[0015] More preferably, the Br content refers to Br - The molar percentage of all halogen anion lattice sites in a trihalogen wide-bandgap perovskite.

[0016] More preferably, the band gap of the trihalomethane wide-bandgap perovskite is 1.65~1.70 eV.

[0017] More preferably, the trihalogen wide-bandgap perovskite is Cs. 0.22 FA 0.78 Pb (I 0.85 Br 0.15 )3 + 5%MAPbCl3.

[0018] More preferably, the 5% refers to the mole fraction of MAPbCl3 in a trihalomethane wide-bandgap perovskite.

[0019] Preferably, the transparent conductive substrate comprises any one of indium tin oxide (ITO), fluorine tin oxide (FTO), aluminum zinc oxide (AZO), or metal nanowire thin films.

[0020] Preferably, the electron transport layer comprises a fullerene (C0)2 60 [6,6]-phenyl-C 61 methyl butyrate (PC) 61 BM, tin dioxide (SnO2) or any one or more of these.

[0021] More preferably, the electron transport layer is C 60 / SnO2 composite layer.

[0022] More preferably, the C 60 In the / SnO2 composite layer, C 60 The thickness of the layer is 12~18 nm, and the thickness of the SnO2 layer is 12~18 nm.

[0023] More preferably, the C 60 In the / SnO2 composite layer, C 60 The thickness of the layer is 15 nm, and the thickness of the SnO2 layer is 15 nm.

[0024] Preferably, the cathode modification layer comprises either copper bath (BCP) or lithium fluoride (LiF).

[0025] Preferably, the top electrode comprises any one of a silver (Ag), copper (Cu), or gold (Au) electrode.

[0026] Preferably, the thickness of the transparent conductive substrate is 90-110 nm, the thickness of the hole transport layer is 15-20 nm, the thickness of the modification layer is 5-20 nm, the thickness of the perovskite light absorption layer is 400-800 nm, the thickness of the electron transport layer is 20-40 nm, the thickness of the cathode modification layer is 30-50 nm, and the thickness of the top electrode is 100-120 nm.

[0027] More preferably, the perovskite solar cell based on nitrogen heterocyclic derivative interface modification includes, from bottom to top, a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light-absorbing layer, an electron transport layer, a cathode modification layer, and a top electrode, wherein the hole transport layer is NiO. x / Ph-4PACz composite layer, and NiO x The Ph-4PACz layer is disposed on a transparent conductive substrate, and the Ph-4PACz layer is disposed on NiO. x The modified layer is obtained by using passivation molecules, which are nitrogen-containing heterocyclic derivatives containing cyano and amino functional groups; the perovskite used in the perovskite light-absorbing layer is Cs. 0.22 FA 0.78 Pb (I 0.85 Br 0.15 )3 +5% MAPbCl3; the electron transport layer is C 60 / SnO2 composite layer, and the C 60 The SnO2 layer is disposed on the perovskite light-absorbing layer, and the SnO2 layer is disposed on C 60 The cathode modification layer is a BCP layer, and the top electrode is a silver electrode.

[0028] Preferably, the passivating molecule interacts with uncoordinated Pb in the perovskite via a cyano group. 2+ The formation of Lewis acid-base pairs, with the amino group reacting with the I group of FAI in the perovskite. - Hydrogen bonds are formed, and the two work synergistically to achieve perovskite defect passivation and ion migration suppression; at the same time, the cyano group is ionized through electron attraction, regulating the hole transport layer NiO. x The defect state of NiO x Chinese Ni 4+ The proportion is reduced, Ni 3+ Increase the proportion and optimize NiO x The Fermi level position promotes p-type charge extraction and improves hole transport efficiency.

[0029] The second objective of this invention is to provide a method for preparing a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, comprising the following steps: S1: Prepare a hole transport layer on a pretreated transparent conductive substrate; S2: Prepare a modification layer on the hole transport layer; S3: Prepare a perovskite light-absorbing layer on the modified layer; S4: An electron transport layer and a cathode buffer layer are fabricated on the perovskite light-absorbing layer; S5: Deposit the top electrode on the electron transport layer to obtain the perovskite solar cell.

[0030] Preferably, in step S1, the pretreatment refers to: ultrasonically cleaning the transparent conductive substrate sequentially with deionized water, acetone, and isopropanol for 10-20 minutes each, drying it with nitrogen, and then treating it with ultraviolet ozone for 10-15 minutes.

[0031] Preferably, in step S1, the hole transport layer is prepared as follows: the material used for the hole transport layer is dissolved in a solvent to prepare a hole transport layer spin coating solution, which is then spin-coated onto a pretreated substrate and annealed at 80~120 °C for 10~30 min to obtain the hole transport layer.

[0032] More preferably, in step S1, the concentration of the hole transport layer spin coating solution is 15~25 mg / ml, the solvent is chlorobenzene or N,N-dimethylformamide, and the spin coating parameters are: spin coating at 3000~4000 rpm for 20~30 s, followed by annealing at 120~150 ℃ for 5~10 min.

[0033] More preferably, in step S1, the hole transport layer is prepared by: using NiO x Hole transport layer spin-coating solution was spin-coated onto a pretreated ITO substrate and annealed at 100°C for 20 min. Subsequently, Ph-4PACz solution was spin-coated onto NiO. x NiO is formed on the layer. x / Ph-4PACz composite hole transport layer.

[0034] Preferably, in step S2, the modification layer is prepared by solution coating, wherein the solution coating method includes any one of spin coating, blade coating, and spray coating.

[0035] Preferably, in step S2, when spin-coating is used, the preparation process of the modified layer is as follows: a nitrogen heterocyclic derivative containing cyano and amino functional groups is dissolved in chlorobenzene or N,N-dimethylformamide to prepare a solution of 1.5~3.0 mg / mL, which is then spin-coated onto the hole transport layer at a speed of 3000~4000 rpm for 20~30 s, and annealed at 80~100 ℃ for 5~10 min to obtain the modified layer.

[0036] Preferably, in step S3, the perovskite light-absorbing layer is prepared by a one-step spin-coating method. The specific process is as follows: the corresponding raw materials are weighed according to the molar ratio of each element in the chemical formula of the trihalomethane perovskite, dissolved in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to prepare a trihalomethane perovskite precursor solution, and then spin-coated onto the modification layer. The spin-coating parameters are: first spin-coating at 1000~1500 rpm for 10~15 s, then spin-coating at 4000~5000 rpm for 30~40 s, with 200~400 μL of anti-solvent added dropwise during the spin-coating process; after spin-coating, annealing is performed at 100~120°C for 20~30 min to form a perovskite light-absorbing layer with a thickness of 400~800 nm.

[0037] More preferably, in step S3, after preparing the perovskite light-absorbing layer, a passivation layer can be selectively spin-coated to protect the stability of the perovskite components.

[0038] More preferably, in step S3, the thickness of the passivation layer is 2~4 nm, and the passivation layer is a piperazine monoiodine passivation layer.

[0039] More preferably, in step S3, the passivation layer is prepared as follows: piperazine monoiodine solution is then spin-coated onto the perovskite substrate at a speed of 4000~5000 rpm for 30~45 s, and then annealed at 100~150℃ for 3~6 minutes to obtain the passivation layer.

[0040] More preferably, in step S3, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide in the mixed solvent is 3~5:1, and even more preferably 4:1.

[0041] More preferably, in step S3, the antisolvent is either anisole or chlorobenzene.

[0042] Preferably, in step S4, the electron transport layer is prepared by thermal evaporation or atomic layer deposition.

[0043] More preferably, in step S4, the electron transport layer is prepared by thermally depositing a 15-20 nm C2 layer. 60Then, 4~6 nm SnO2 is deposited at 100 °C using atomic layer deposition (ALD).

[0044] More preferably, in step S4, SnO2 and C 60 Together they serve as an electron transport layer, while SnO2 acts as a modification buffer layer.

[0045] More preferably, in step S5, the cathode modification layer and the top electrode are obtained by thermal evaporation deposition.

[0046] More preferably, in step S5, the parameters for depositing and preparing the top electrode are 0.5~1 Å·s. -1 A 100-120 nm silver electrode is thermally deposited at a rate of [missing information].

[0047] More preferably, the method for preparing the perovskite solar cell based on the interface modification of nitrogen heterocyclic derivatives includes the following steps: 1. Pretreatment of transparent conductive substrate: The transparent conductive substrate is ultrasonically cleaned with deionized water, acetone and isopropanol for 10-20 min in sequence, dried with nitrogen and then treated with ultraviolet ozone for 10-15 min. 2. Preparation of hole transport layer: Dissolve the hole transport layer material in a solvent, spin-coat it onto the pretreated substrate, and anneal at 80~120℃ for 10~30 min; 3. Preparation of the modified layer: Dissolve the nitrogen heterocyclic derivative in isopropanol to prepare a solution of 1.5~3.0 mg / mL, spin-coat it onto the hole transport layer at 3000~4000 rpm for 20~30 s, and anneal at 80~100℃ for 5~10 min; the modified layer and the uncoordinated Pb in the perovskite light-absorbing layer... 2+ It forms coordinate bonds and hydrogen bonds with formamidinium iodide (FAI); 4. Preparation of the perovskite light-absorbing layer: A one-step spin-coating method was used to spin-coat a trihalomethane perovskite precursor solution (a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1) onto the modification layer. During spin-coating, 200-400 μL of anti-solvent (anisole / chlorobenzene) was added dropwise. The spin-coating parameters were: first spin-coating at 1000-1500 rpm for 10-15 s, then spin-coating at 4000-5000 rpm for 30-40 s, followed by annealing at 100-120°C for 20-30 min to form a perovskite film with a thickness of 400-800 nm. A passivating agent was added, and a piperazine monoiodine (PI) solution was spin-coated onto the prepared perovskite substrate at 4000 rpm for 30 seconds, followed by annealing at 100°C for 5 minutes. 5. Preparation of electron transport layer: The electron transport layer was prepared by vacuum evaporation and atomic layer deposition; 6. Preparation of cathode modification layer and top electrode: The cathode modification layer and top electrode are deposited sequentially by thermal evaporation to obtain the perovskite solar cell.

[0048] The third objective of this invention is to provide a perovskite / silicon tandem solar cell, comprising a silicon bottom cell and a top cell disposed on the silicon bottom cell.

[0049] Preferably, the silicon-based solar cell includes an n-type solar-grade monocrystalline silicon wafer substrate. On one side surface of the monocrystalline silicon wafer substrate, from the direction closest to the surface to the direction furthest from the surface, an intrinsic hydrogenated amorphous silicon layer (ia-Si:H), a boron-doped hydrogenated microcrystalline silicon layer (p-μc-Si:H), and an indium zinc oxide thin film layer (IZO) are sequentially disposed. On the opposite side surface, from the direction closest to the surface to the direction furthest from the surface, an intrinsic hydrogenated amorphous silicon layer, a phosphorus-doped hydrogenated microcrystalline silicon oxide layer (n-μc-SiOx:H), an indium tin oxide thin film layer (ITO), and a silver electrode layer are sequentially disposed.

[0050] Preferably, the top battery comprises a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, an electrode layer, and an antireflection layer sequentially disposed on an indium zinc oxide thin film layer, wherein the modification layer uses the aforementioned passivation molecule, and the passivation molecule is a nitrogen heterocyclic derivative containing cyano and amine functional groups.

[0051] Preferably, the electrode layer comprises a silver gate layer, and the antireflective layer comprises lithium fluoride (LiF).

[0052] Preferably, the resistivity of the n-type solar-grade monocrystalline silicon wafer substrate is 0.8~1.2 Ω·cm, the thickness is 115~145 μm, the thickness of the intrinsic hydrogenated amorphous silicon layer is 3~5 nm, the thickness of the boron-doped hydrogenated microcrystalline silicon layer is 15~20 nm, the thickness of the indium zinc oxide thin film layer is 15~20 nm, the thickness of the phosphorus-doped hydrogenated microcrystalline silicon oxide layer is 15~20 nm, the thickness of the indium tin oxide thin film layer is 90~100 nm, the thickness of the electrode layer is 750~850 nm, and the thickness of the antireflection layer is 100~130 nm.

[0053] More preferably, the dimensions of the indium zinc oxide thin film layer and the indium tin oxide thin film layer are both 1.1 × 1.1 cm.

[0054] The fourth objective of this invention is to provide a method for preparing the perovskite / silicon tandem solar cell, comprising the following steps: A: On one side of an n-type solar-grade monocrystalline silicon wafer substrate that has undergone wet chemical texturing, an intrinsic hydrogenated amorphous silicon layer and a boron-doped hydrogenated microcrystalline silicon layer are sequentially prepared by plasma-enhanced chemical vapor deposition (PECVD). On the other side of the substrate, an intrinsic hydrogenated amorphous silicon layer and a phosphorus-doped hydrogenated microcrystalline silicon oxide layer are sequentially prepared by plasma-enhanced chemical vapor deposition, forming an n-μc-SiOx:H / ia-Si:H / c-Si / ia-Si:H / p-μc-Si:H structure. B: An indium zinc oxide thin film layer is prepared by sputtering deposition on a boron-doped hydrogenated microcrystalline silicon layer, and an indium tin oxide thin film layer and a silver electrode layer are prepared by sputtering deposition sequentially on a phosphorus-doped hydrogenated microcrystalline silicon oxide layer. Then, the sputtering damage is repaired by annealing treatment, and the silicon bottom battery is obtained by laser cutting. C: A hole transport layer, a modification layer, a perovskite light absorption layer, and an electron transport layer are sequentially prepared on an indium zinc oxide thin film layer of a silicon-based solar cell. D: An electrode layer is deposited on the electron transport layer by thermal evaporation using a mask, and finally an antireflection layer is deposited by thermal evaporation to obtain the perovskite / silicon tandem solar cell.

[0055] Preferably, in step B, the annealing treatment refers to annealing at 180~220 ℃ for 10~20 minutes.

[0056] Preferably, in step B, the silicon bottom cell obtained by laser cutting is 2.5 cm × 2.5 cm.

[0057] More preferably, the perovskite / silicon tandem solar cell is prepared as follows: Silicon-based solar cell fabrication: An n-type solar-grade monocrystalline silicon (c-Si) wafer with a resistivity of 1.0 Ω·cm and a thickness of 130 μm was used as the substrate. After wet chemical texturing, the wafer was transferred to a plasma-enhanced chemical vapor deposition (PECVD) chamber, where intrinsic hydrogenated amorphous silicon (ia-Si:H), phosphorus-doped hydrogenated microcrystalline silicon oxide (n-μc-SiOx:H), and boron-doped hydrogenated microcrystalline silicon (p-μc-Si:H) layers were deposited sequentially, forming an n-μc-SiOx:H / ia-Si:H / c-Si / ia-Si:H / p-μc-Si:H structure. An indium tin oxide (ITO) layer was sputtered onto the back side of the wafer, followed by a back silver electrode. A 15 nm thick indium zinc oxide (IZO) film was deposited on the front side (the dimensions of the front and back transparent conductive oxide (TCO) layers were both 1.1 × 1.1 cm). The wafer was annealed at 200 °C for 15 minutes to repair sputtering damage and then laser-cut to a 2.5 cm thickness. A substrate measuring 2.5 cm in diameter.

[0058] Top cell fabrication: The fabrication process of the perovskite cell described above was adopted with some modifications. A 50 nm thick layer of tin oxide (SnO) was deposited. x After using a transparent electrode made of indium tin oxide (ITO), a silver gate with a thickness of 800 nm is deposited by thermal evaporation using a high-precision shadow mask. Finally, a 115 nm thick lithium fluoride (LiF) layer is deposited by thermal evaporation as an antireflection layer. Combined with a silicon substrate cell, a perovskite / silicon tandem cell is obtained.

[0059] To address the issues of defects in the perovskite light-absorbing layer and low carrier transport efficiency between the perovskite and transport layers, current research strategies primarily rely on interface modification to passivate defects in both the perovskite and transport layers. However, most studies only target perovskite defects with these modification layers, neglecting the significant impact of the quality of the buried interface (perovskite / hole transport layer interface) on perovskite film formation. Therefore, utilizing the synergistic effects of multiple functional groups to simultaneously passivate trihalomethane wide-bandgap perovskites and hole transport layers, such as NiO, is crucial. x The strategy of improving the contact between the hole transport layer and the perovskite and suppressing nonradiative recombination of charge carriers by exploiting the defects of the hole transport layer is rarely reported.

[0060] Based on the aforementioned technological gaps, this invention combines functional group characteristics with battery interface mechanisms to propose a targeted technical concept: N atoms can interact with Pb in perovskites. 2+ Defect formation and coordination enable defect passivation; therefore, molecules containing cyano groups (-CN) are widely used as passivating agents to optimize perovskite grain size and improve film quality. Simultaneously, the -CN group readily ionizes through electron attraction, which can modulate the NiO group. x The defect states are identified and their Fermi level positions are optimized, thereby improving carrier transport capability. Furthermore, the amine group (-NH2) can react with the I group of FAI in the perovskite composition. - Hydrogen bonds are formed, effectively eliminating surface defects in perovskites and enhancing their stability. Based on this, this invention screened 10 nitrogen heterocyclic derivatives containing cyano (-CN) and amino (-NH2) functional groups as passivating agents, achieving multi-effect optimization through the synergistic effect of multiple functional groups.

[0061] The core technical concept of this invention is specifically embodied in the following three aspects: First, one of 10 target nitrogen heterocyclic derivatives was selected as a passivating agent, utilizing the -CN group to react with uncoordinated Pb in perovskite. 2+ The synergistic effect of forming Lewis acid-base pairs and hydrogen bonds between the -NH2 group and FAI simultaneously achieves perovskite defect passivation and ion migration suppression; compared to unmodified NiO X Thin film, NiO modified according to the present invention x Ni in thin films 4+ The proportion is reduced, Ni 3+ The proportion increases, while Ni3+ Increased content can promote p-type charge extraction, Ni 4+ The strong oxidizing properties of the material may have a negative impact on the perovskite layer. Therefore, the modified hole transport layer (HTL) is more conducive to hole transport, effectively solving the technical problem that traditional passivators cannot achieve multiple optimization effects.

[0062] Secondly, a battery structure consisting of "transparent conductive substrate, hole transport layer, modification layer, trihalomethane WBG perovskite light absorption layer, electron transport layer, cathode modification layer, and top electrode" was designed. The nitrogen heterocyclic derivative modification layer was precisely placed between the hole transport layer and the perovskite light absorption layer to specifically improve the interfacial energy level mismatch problem and enhance the carrier transport efficiency.

[0063] Third, by optimizing the composition and preparation process of trihalomethane wide-bandgap perovskite and combining it with the synergistic effect of the modification layer, the density of defects in the perovskite film and at the interface is effectively reduced under the condition that the Br content is ≤15%, avoiding the problem of poor crystallization caused by high Br content. Ultimately, the efficiency of the battery device is significantly improved compared with the perovskite solar cell without the modification layer of this invention.

[0064] In terms of process technology, this invention has overcome key technical difficulties: it has solved the problem of self-assembled monolayers (SAMs) in traditional hole transport layers (such as NiO). x Insufficient coverage on the perovskite layer leads to poor contact with the perovskite precursor solution during spin coating, and may erode the perovskite components after annealing, resulting in poor crystallinity and stability of the subsequently deposited perovskite film. By adding a modification layer, not only is the interfacial contact with the perovskite layer strengthened, but the interfacial energy level arrangement is also optimized, thereby improving the crystallinity of the perovskite film and further enhancing the stability and photoelectric performance of the battery.

[0065] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a perovskite solar cell based on interface modification of nitrogen heterocyclic derivatives. Its structure consists of a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, a cathode modification layer, and a top electrode from bottom to top. The passivation molecule used in the modification layer is a nitrogen heterocyclic derivative containing cyano and amino functional groups. Based on this modification layer, the defects of the perovskite layer and the hole transport layer can be optimized at the same time, reducing the non-radiative recombination efficiency in WBG perovskite, solving the energy level mismatch problem between the perovskite layer and the charge transport layer, realizing energy level optimization, and improving the separation and transport of charge carriers.

[0066] (2) Significant defect passivation effect: The cyano group of nitrogen heterocyclic derivatives and the uncoordinated Pb 2+Coordination occurs, with amino groups forming hydrogen bonds with FAI in the perovskite. This dual effect suppresses perovskite defects and ion migration, significantly reducing the defect state density of the perovskite film. Simultaneously, it can modulate the hole transport layer (such as NiO). x The defect states of NiO are reduced, its defect density is decreased, and the Fermi level position is optimized (so that NiO is reduced). x Chinese Ni 4+ The proportion is reduced, Ni 3+ The proportion of charge carrier non-radiative recombination loss is increased, effectively improving the photoelectric conversion efficiency of the device. Specifically, when one of the following is used as a passivation molecule to construct the modification layer, the current, voltage, fill factor and photoelectric conversion efficiency of the battery are significantly improved compared with the control group (without the modification layer): 3-amino-2-cyanopyridine, 5-amino-2-cyanopyridine, 5,6-diamino-2-cyanopyridine, 5-amino-2,3-dicyanopyridine, 5,6-diamino-2,3-dicyanopyridine, 3-amino-2-cyanopyrazine, 5-amino-2-cyanopyrazine, 5-amino-2,3-dicyanopyrazine, 3,6-diamino-2,5-dicyanopyrazine, and 5,6-diamino-2,3-dicyanopyrazine.

[0067] (3) Energy level matching optimization: Based on the dual defect passivation effect of the modification layer on the perovskite layer and the hole transport layer, the energy level shift between the hole transport layer and the perovskite is effectively reduced, promoting rapid hole extraction, significantly improving the battery fill factor (FF), further improving the carrier transport efficiency, and contributing to the improvement of device performance.

[0068] (4) Enhanced stability: The perovskite solar cells and perovskite / silicon tandem solar cells based on the present invention exhibit excellent long-term operational stability, solving the problem of poor stability of existing wide bandgap (WBG) perovskite devices, and laying the foundation for commercial application.

[0069] (5) Strong compatibility of preparation process: The modification layer is prepared by solution coating method, which is simple and low cost. It is compatible with the existing perovskite battery preparation process and is easy to scale up. Attached Figure Description

[0070] Figure 1 This is the chemical structural formula of the passivation molecule used in the modification layer of this invention; Figure 2 This is the device structure of the perovskite solar cell of the present invention; Figure 3 The diagram illustrates the principle of energy level optimization achieved by the modification layer of the present invention (in the figure, A is the energy level structure of the perovskite solar cell without the modification layer in Comparative Example 1, and B is the energy level structure of the perovskite solar cell with the modification layer in Example 1). Figure 4The following is a statistical chart of the photovoltaic performance of each group of perovskite solar cells prepared in Example 1 of the present invention (in the figure, A is the open-circuit voltage, B is the short-circuit current density, C is the fill factor, and D is the photoelectric conversion efficiency). Figure 5 The current-voltage curves of the perovskite solar cells prepared in Example 1 and Comparative Example 1 of this invention are shown. Figure 6 The graph shows the photoelectric conversion efficiency of the perovskite / silicon tandem solar cells prepared in Example 2 and Comparative Example 2 of this invention.

[0071] Figure 7 The graph shows the stability of photoelectric conversion efficiency of the perovskite / silicon tandem solar cells prepared in Example 2 and Comparative Example 2 of this invention. Detailed Implementation

[0072] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0073] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0074] This invention first provides a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, the structure of which is shown below. Figure 2 It includes, from bottom to top, a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, a cathode modification layer, and a top electrode. The modification layer is obtained by using passivation molecules, which are nitrogen heterocyclic derivatives containing cyano and amino functional groups.

[0075] The passivating molecule is selected from any one of the following nitrogen heterocyclic derivatives: 3-amino-2-cyanopyridine, 5-amino-2-cyanopyridine, 5,6-diamino-2-cyanopyridine, 5-amino-2,3-dicyanopyridine, 5,6-diamino-2,3-dicyanopyridine, 3-amino-2-cyanopyrazine, 5-amino-2-cyanopyrazine, 5-amino-2,3-dicyanopyrazine, 3,6-diamino-2,5-dicyanopyrazine, and 5,6-diamino-2,3-dicyanopyrazine; the chemical formula of each passivating molecule is shown in [reference needed]. Figure 1 ; The hole transport layer comprises one or more of nickel oxide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphoric acid; the perovskite light-absorbing layer is a trihalomethane wide-bandgap perovskite and also contains Cl. - ,Br - I - The three halide ions have a Br content ≤15% and a band gap of 1.65~1.70 eV. The transparent conductive substrate includes any one of indium tin oxide, fluorine tin oxide, aluminum zinc oxide, or metal nanowire thin films; the electron transport layer includes fullerene, [6,6]-phenyl-C 61 - Methyl butyrate, tin dioxide, or any one or more of the following; the cathode modification layer includes any one of copper bath or lithium fluoride; the top electrode includes any one of silver, copper, or gold electrodes. The thickness of the transparent conductive substrate is 90~110 nm, the thickness of the hole transport layer is 15~20 nm, the thickness of the modification layer is 5~20 nm, the thickness of the perovskite light absorption layer is 400~800 nm, the thickness of the electron transport layer is 20~40 nm, the thickness of the cathode modification layer is 30~50 nm, and the thickness of the top electrode is 100~120 nm.

[0076] The aforementioned method for preparing perovskite solar cells based on interface modification with nitrogen heterocyclic derivatives includes the following steps: S1: Prepare a hole transport layer on a pretreated transparent conductive substrate; the pretreatment refers to: ultrasonically cleaning the transparent conductive substrate with deionized water, acetone and isopropanol for 10-20 min each, drying it with nitrogen and then treating it with ultraviolet ozone for 10-15 min. S2: Preparation of a modification layer on the hole transport layer: The modification layer is prepared by a solution coating method, which includes any one of spin coating, blade coating, or spray coating. When spin coating is used, the preparation process of the modification layer is as follows: A nitrogen heterocyclic derivative containing cyano and amino functional groups is dissolved in isopropanol to prepare a solution of 1.5~3.0 mg / mL. The solution is then spin-coated onto the hole transport layer at a speed of 3000~4000 rpm for 20~30 s. The solution is then annealed at 80~100℃ for 5~10 min to obtain the modification layer.

[0077] S3: Prepare a perovskite light-absorbing layer on the modified layer; wherein, the perovskite light-absorbing layer is prepared by a one-step spin-coating method, the specific process of which is as follows: weigh the corresponding raw materials according to the molar ratio of each element in the chemical formula of trihalomethane perovskite, dissolve them in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide to prepare a trihalomethane perovskite precursor solution, and spin-coat it onto the modified layer. The spin-coating parameters are: first spin-coat at 1000~1500 rpm for 10~15 s, then spin-coat at 4000~5000 rpm for 30~40 s, adding 200~400 μL of anti-solvent during the spin-coating process; after spin-coating, anneal at 100~120℃ for 20~30 min to form a perovskite light-absorbing layer with a thickness of 400~800 nm; the N,N-dimethylformamide in the mixed solvent is added to the modified layer. The volume ratio of dimethylformamide to dimethyl sulfoxide is 3~5:1, and the antisolvent is anisole or chlorobenzene; after the perovskite light-absorbing layer is prepared, a passivation layer can be selectively spin-coated to protect the stability of the perovskite components. S4: Fabrication of an electron transport layer on a perovskite light-absorbing layer; S5: A cathode modification layer and a top electrode are sequentially fabricated on the electron transport layer to obtain a perovskite solar cell.

[0078] The present invention also provides a perovskite / silicon tandem solar cell, comprising a silicon base cell and a top cell disposed on the silicon base cell. The silicon base cell comprises an n-type solar-grade monocrystalline silicon wafer substrate. On one side surface of the monocrystalline silicon wafer substrate, from the direction near its surface to the direction away from its surface, an intrinsic hydrogenated amorphous silicon layer, a boron-doped hydrogenated microcrystalline silicon layer, and an indium zinc oxide thin film layer are sequentially disposed. On the opposite side surface, from the direction near its surface to the direction away from its surface, an intrinsic hydrogenated amorphous silicon layer, a phosphorus-doped hydrogenated microcrystalline silicon oxide layer, an indium tin oxide thin film layer, and a silver electrode layer are sequentially disposed on the indium zinc oxide thin film layer. The top cell comprises a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, an electrode layer, and an antireflection layer sequentially disposed on the indium zinc oxide thin film layer. The modification layer uses the aforementioned passivation molecule, which is a nitrogen heterocyclic derivative containing cyano and amine functional groups.

[0079] The fabrication method of this perovskite / silicon tandem solar cell includes the following steps: A: On one side of an n-type solar-grade monocrystalline silicon wafer substrate that has undergone wet chemical texturing, an intrinsic hydrogenated amorphous silicon layer and a boron-doped hydrogenated microcrystalline silicon layer are sequentially prepared by plasma-enhanced chemical vapor deposition. On the other side of the substrate, an intrinsic hydrogenated amorphous silicon layer and a phosphorus-doped hydrogenated microcrystalline silicon oxide layer are sequentially prepared by plasma-enhanced chemical vapor deposition. B: An indium zinc oxide thin film layer was prepared by sputtering deposition on a boron-doped hydrogenated microcrystalline silicon layer, and an indium tin oxide thin film layer and a silver electrode layer were prepared by sputtering deposition sequentially on a phosphorus-doped hydrogenated microcrystalline silicon oxide layer. Subsequently, the sputtering damage was repaired by annealing, and the silicon bottom cell was obtained by laser cutting. C: A hole transport layer, a modification layer, a perovskite light absorption layer, and an electron transport layer are sequentially prepared on an indium zinc oxide thin film layer of a silicon-based solar cell. D: Electrode layers are deposited on the electron transport layer by thermal evaporation using a mask, and finally an antireflection layer is deposited by thermal evaporation to obtain a perovskite / silicon tandem solar cell.

[0080] Example 1: Perovskite solar cell modified with a single passivator Experimental materials and equipment Materials: Transparent conductive substrate (ITO / FTO), hole transport layer material (NiO) x Ph-4PACz), nitrogen heterocyclic derivatives (3-amino-2-cyanopyridine, 5-amino-2-cyanopyridine, 5,6-diamino-2-cyanopyridine, 5-amino-2,3-dicyanopyridine, 5,6-diamino-2,3-dicyanopyridine, 3-amino-2-cyanopyrazine, 5-amino-2-cyanopyrazine, 5-amino-2,3-dicyanopyrazine, 3,6-diamino-2,5-dicyanopyrazine, 5,6-diamino-2,3-dicyanopyrazine, their chemical formulas are shown in [reference needed] Figure 1 Trihalomethane perovskite precursor materials (CsI, FAI, MAI, PbI2, PbBr2, PbCl2, etc.), electron transport layer materials (C 60 (SnO2), cathode modification layer material (BCP), top electrode material (Ag), solvent (DMF, DMSO, isopropanol, anisole, chlorobenzene, etc.).

[0081] Equipment: Ultrasonic cleaner, UV ozone cleaner, high-speed mixer, spin coater, annealing furnace, thermal evaporation equipment, laser cutting machine, photovoltaic performance testing system.

[0082] The specific preparation process is as follows: Substrate pretreatment: Take an ITO transparent conductive substrate, and ultrasonically clean it with deionized water, acetone and isopropanol for 15 min each, blow it dry with nitrogen and then treat it with ultraviolet ozone for 12 min.

[0083] Hole transport layer preparation: NiO x The material was dissolved in an appropriate amount of solvent, spin-coated onto a pretreated ITO substrate, and annealed at 100°C for 20 min. Subsequently, the Ph-4PACz solution was spin-coated onto NiO. x NiO is formed on the layer. x / Ph-4PACz composite hole transport layer, wherein NiO x The thickness of the layer is 15 nm, and the thickness of the Ph-4PACz layer is 5 nm.

[0084] Preparation of modified layers: Taking 3-amino-2-cyanopyridine (Chemical Formula 1), 5,6-diamino-2-cyanopyridine (Chemical Formula 3), 3-amino-2-cyanopyrazine (Chemical Formula 6), and 5-amino-2,3-dicyanopyrazine (Chemical Formula 8) as examples, the four corresponding small organic molecules were weighed and dissolved in chlorobenzene or N,N-dimethylformamide to prepare a 2.0 mg / mL solution. The solution was spin-coated onto the hole transport layer at 3500 rpm for 25 s and annealed at 90℃ for 8 min to obtain the substrates of four different modified layers.

[0085] Preparation of perovskite light-absorbing layer: according to Cs 0.22 FA 0.78 Pb (I 0.85 Br 0.15 The chemical formula of 3 + 5% MAPbCl3 was used to prepare a perovskite precursor solution by dissolving CsI, FAI, MAI, PbI2, PbBr2, and PbCl2 in a DMF / DMSO mixed solvent (volume ratio 4:1). The precursor solution was spin-coated onto the modification layer, with 300 μL of anisole antisolvent added dropwise during the spin-coating process. The spin-coating parameters were as follows: spin-coating at 1200 rpm for 12 s, then at 4500 rpm for 35 s, followed by annealing at 110℃-160℃ for 25 min to form a 500 nm perovskite film. Then, piperazine monoiodine solution was spin-coated at 4000 rpm for 30 s and annealed at 100℃ for 5 min. The thickness of the piperazine monoiodine layer was 3 nm.

[0086] Fabrication of electron transport layer and cathode modification layer: 15 nm C was deposited by thermal evaporation. 60 A 15nm SnO2 layer was deposited at 100 °C to form C. 60 / SnO2 composite electron transport layer.

[0087] Top electrode fabrication: A 120 nm thick silver (Ag) electrode was deposited by thermal evaporation at a rate of 0.5–1 Å / s.

[0088] Comparative Example 1: Perovskite solar cell without modification layer Following the above-described fabrication process, only the modification layer preparation step is omitted, while keeping the other process parameters consistent, to obtain a perovskite solar cell without a modification layer.

[0089] Figure 3Figure A is a schematic diagram illustrating the principle of energy level optimization achieved by the modification layer of the present invention. Figure A shows the energy level structure of the perovskite solar cell without the modification layer in Comparative Example 1, and Figure B shows the energy level structure of the perovskite solar cell with the modification layer in Example 1. As can be seen from the figures, in Comparative Example 1 without the modification layer, there is an energy level mismatch between the wide bandgap (WBG) perovskite and the hole transport layer. A significant energy level shift exists between the perovskite energy level (-5.32 eV) and the hole transport layer energy level, which hinders carrier transport at the interface and easily leads to non-radiative recombination, thus limiting the fill factor (FF) and photoelectric conversion efficiency of the cell. When the nitrogen heterocyclic derivative modification layer described in this invention is introduced between the hole transport layer and the perovskite light absorption layer, the overall energy level structure is significantly optimized. After the introduction of the modification layer, its energy level position (-5.45 eV) serves as a transition layer, effectively filling and regulating the energy level barrier between the perovskite and the hole transport layer, achieving interface energy level optimization and reducing carrier recombination losses at the interface.

[0090] The photovoltaic performance of the perovskite solar cells prepared in Example 1 and Comparative Example 1 was tested. The test results... Figure 4 It can be seen that, compared with Comparative Example 1 without modification, the perovskite solar cell using nitrogen heterocyclic derivatives as the modification layer shows improvements in open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency. Among these, the fill factor improvement is the most significant (approximately 2.2%), indicating an effective reduction in device carrier losses. The device's current-voltage diagram ( Figure 5 The modified device also demonstrated a significant improvement in current and voltage compared to the control group. The device comparison fully demonstrates the superior effectiveness of this invention in defect passivation, energy level optimization, and carrier transport improvement.

[0091] Example 2 According to the above-described perovskite / silicon tandem solar cell preparation method, the perovskite top cell (using chemical formula 3 as the modification layer) in Example 1 is combined with the silicon bottom cell to prepare a perovskite / silicon tandem solar cell containing the modification layer.

[0092] N-type solar-grade monocrystalline silicon (c-Si) wafers with a resistivity of 1.0 Ω·cm and a thickness of 130 μm were used as the substrate. First, these wafers were textured using a wet chemical process. Subsequently, the wafers were transferred to a plasma-enhanced chemical vapor deposition (PECVD) chamber, where intrinsic hydrogenated amorphous silicon (ia-Si:H), doped phosphohydrogenated microcrystalline silicon oxide (n-μc-SiOx:H), and boron-doped hydrogenated microcrystalline silicon (p-μc-S:H) layers were deposited sequentially, ultimately forming a structure of n-μc-SiOx:H / ia-Si:H / c-Si / ia-Si:H / p-μc-Si:H. To complete the fabrication of the silicon-based solar cell, an indium tin oxide (ITO) layer was sputtered onto the back of the wafer, followed by back mercury deposition. Then, a 15 nm thick IZO film was deposited on the front. The total area of ​​the front and back TCO layers was 1.1 × 1.1 cm². 2 To recover from sputtering damage, an annealing process was performed at 200 °C for 15 minutes. Afterward, the bottom cells of the SHJ were laser-cut to a 2.50 cm × 2.50 cm substrate for tandem fabrication.

[0093] The manufacturing process for the top-mounted cells is similar to that of single-junction perovskite solar cells, but with some modifications. SnO deposition... x Alternatively, after an ITO transparent electrode, a silver gate with a thickness of 800 nm is deposited by thermal evaporation using a high-precision shadow mask. Finally, a lithium fluoride (LiF) layer with a thickness of 115 nm is deposited by thermal evaporation as an antireflection layer. This is combined with a silicon substrate cell to obtain a perovskite / silicon tandem cell.

[0094] Comparative Example 2 Following the above-described method for preparing perovskite / silicon tandem solar cells, the perovskite top cell from Comparative Example 1 was combined with the silicon bottom cell to prepare a perovskite / silicon tandem solar cell.

[0095] Tests showed that the photoelectric conversion efficiency of this tandem battery was improved, such as... Figure 6 As shown, the highest-performing device has a PCE exceeding 31%, and exhibits excellent efficiency and stability after 600 hours of continuous illumination. Figure 7 As shown in the figure, this verifies the applicability of the technical solution in stacked batteries.

[0096] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives, characterized in that, The device comprises, from bottom to top, a transparent conductive substrate, a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, a cathode modification layer, and a top electrode. The modification layer is obtained by using passivation molecules, which are nitrogen heterocyclic derivatives containing cyano and amino functional groups.

2. The perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives according to claim 1, characterized in that, The passivating molecule is selected from any of the following nitrogen heterocyclic derivatives: 3-amino-2-cyanopyridine, 5-amino-2-cyanopyridine, 5,6-diamino-2-cyanopyridine, 5-amino-2,3-dicyanopyridine, 5,6-diamino-2,3-dicyanopyridine, 3-amino-2-cyanopyrazine, 5-amino-2-cyanopyrazine, 5-amino-2,3-dicyanopyrazine, 3,6-diamino-2,5-dicyanopyrazine, 5,6-diamino-2,3-dicyanopyrazine.

3. The perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives according to claim 1, characterized in that, The hole transport layer comprises one or more of nickel oxide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphoric acid; the perovskite light absorption layer is a trihalomethane wide-bandgap perovskite, and also contains Cl. - ,Br - I - The three halide ions have a Br content ≤15% and a band gap of 1.65~1.70 eV.

4. A perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives according to claim 1, characterized in that, The transparent conductive substrate comprises any one of indium tin oxide, fluorine tin oxide, aluminum zinc oxide, or metal nanowire thin films; the electron transport layer comprises fullerene, [6,6]-phenyl-C 61 1-Methyl butyrate, tin dioxide, or any one or more thereof; the cathode modification layer includes any one of copper bath or lithium fluoride; the top electrode includes any one of silver, copper, or gold electrodes.

5. A perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives according to claim 1, characterized in that, The thickness of the transparent conductive substrate is 90-110 nm, the thickness of the hole transport layer is 15-20 nm, the thickness of the modification layer is 5-20 nm, the thickness of the perovskite light absorption layer is 400-800 nm, the thickness of the electron transport layer is 20-40 nm, the thickness of the cathode modification layer is 30-50 nm, and the thickness of the top electrode is 100-120 nm.

6. A method for preparing a perovskite solar cell based on interface modification with nitrogen heterocyclic derivatives as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Prepare a hole transport layer on a pretreated transparent conductive substrate; S2: Prepare a modification layer on the hole transport layer; S3: Prepare a perovskite light-absorbing layer on the modified layer; S4: Fabrication of an electron transport layer on a perovskite light-absorbing layer; S5: A cathode modification layer and a top electrode are sequentially fabricated on the electron transport layer to obtain the perovskite solar cell.

7. The preparation method according to claim 6, characterized in that, In step S2, a modified layer is prepared using a solution coating method, which includes any one of spin coating, blade coating, or spray coating. When spin coating is used, the preparation process of the modified layer is as follows: a nitrogen heterocyclic derivative containing cyano and amino functional groups is dissolved in isopropanol to prepare a solution of 1.5~3.0 mg / mL, which is then spin-coated onto the hole transport layer at a speed of 3000~4000 rpm for 20~30 s, and annealed at 80~100℃ for 5~10 min to obtain the modified layer.

8. The preparation method according to claim 6, characterized in that, In step S3, the perovskite light-absorbing layer is prepared by a one-step spin-coating method. The specific process is as follows: the corresponding raw materials are weighed according to the molar ratio of each element in the chemical formula of the trihalomethane perovskite, dissolved in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide to prepare a trihalomethane perovskite precursor solution, and then spin-coated onto the modification layer. The spin-coating parameters are: first spin-coating at 1000~1500 rpm for 10~15 s, then spin-coating at 4000~5000 rpm for 30~40 s, with 200~400 μL of anti-solvent added dropwise during the spin-coating process; after spin-coating, annealing is performed at 100~120℃ for 20~30 min to form a perovskite light-absorbing layer with a thickness of 400~800 nm. The volume ratio of N,N-dimethylformamide to dimethyl sulfoxide in the mixed solvent is 3-5:1, and the antisolvent is anisole or chlorobenzene.

9. A perovskite / silicon tandem solar cell, characterized in that, The device includes a silicon-based solar cell and a top cell disposed on the silicon-based solar cell. The silicon-based solar cell includes an n-type solar-grade monocrystalline silicon wafer substrate. On one side surface of the monocrystalline silicon wafer substrate, from the direction closest to the surface to the direction furthest from the surface, an intrinsic hydrogenated amorphous silicon layer, a boron-doped hydrogenated microcrystalline silicon layer, and an indium zinc oxide thin film layer are sequentially disposed. On the opposite side surface, from the direction closest to the surface to the direction furthest from the surface, an intrinsic hydrogenated amorphous silicon layer, a phosphorus-doped hydrogenated microcrystalline silicon oxide layer, an indium tin oxide thin film layer, and a silver electrode layer are sequentially disposed. The top battery comprises a hole transport layer, a modification layer, a perovskite light absorption layer, an electron transport layer, an electrode layer, and an antireflection layer sequentially disposed on an indium zinc oxide thin film layer, wherein the modification layer adopts the passivation molecule as described in any one of claims 1 to 5, and the passivation molecule is a nitrogen heterocyclic derivative containing cyano and amino functional groups.

10. The method for preparing a perovskite / silicon tandem solar cell according to claim 9, characterized in that, Includes the following steps: A: On one side of an n-type solar-grade monocrystalline silicon wafer substrate that has undergone wet chemical texturing, an intrinsic hydrogenated amorphous silicon layer and a boron-doped hydrogenated microcrystalline silicon layer are sequentially prepared by plasma-enhanced chemical vapor deposition. On the other side of the substrate, an intrinsic hydrogenated amorphous silicon layer and a phosphorus-doped hydrogenated microcrystalline silicon oxide layer are sequentially prepared by plasma-enhanced chemical vapor deposition. B: An indium zinc oxide thin film layer is prepared by sputtering deposition on a boron-doped hydrogenated microcrystalline silicon layer, and an indium tin oxide thin film layer and a silver electrode layer are prepared by sputtering deposition sequentially on a phosphorus-doped hydrogenated microcrystalline silicon oxide layer. Then, the sputtering damage is repaired by annealing treatment, and the silicon bottom battery is obtained by laser cutting. C: A hole transport layer, a modification layer, a perovskite light absorption layer, and an electron transport layer are sequentially prepared on an indium zinc oxide thin film layer of a silicon-based solar cell. D: An electrode layer is deposited on the electron transport layer by thermal evaporation using a mask, and finally an antireflection layer is deposited by thermal evaporation to obtain the perovskite / silicon tandem solar cell.

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