A three-dimensional molecular synergistic passivated perovskite solar cell and a preparation method thereof

Abstract

This invention belongs to the field of perovskite solar cell technology, specifically disclosing a three-dimensional molecularly synergistic passivation perovskite solar cell and its fabrication method. The perovskite solar cell has a p-i-n structure, consisting of a transparent ITO conductive glass substrate, a hole transport layer, a buried passivation layer, a perovskite light-absorbing layer, an upper interface passivation layer, an electron transport layer, a physical isolation layer, and a metal electrode layer, from bottom to top. This invention introduces 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide (DMBI-I), 2-thiopheneethylamine ammonium iodide (TEAI), and 4-methoxyphenylethyl ammonium iodide (4-MeO-PEAI) to design a three-dimensional gradient passivation architecture of "buried interface-bulk phase-upper interface" in the vertical spatial dimension of the perovskite solar cell. This systematically and synergistically solves a series of interconnected bottleneck problems, from interfacial chemical instability and bulk defect recombination to poor surface charge extraction.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a three-dimensional molecularly co-passivated perovskite solar cell and its preparation method. Background Technology

[0002] Perovskite solar cells possess extremely high absorption coefficients, achieving efficient absorption of the entire visible light spectrum with a thickness of only a few hundred nanometers. Simultaneously, their carrier diffusion length can reach the micrometer level, significantly reducing recombination losses and driving rapid improvements in device efficiency. In terms of fabrication processes, perovskite can be prepared using techniques such as solution spin coating, inkjet printing, or vapor deposition, greatly reducing energy consumption and equipment costs. Device efficiencies on flexible substrates have also exceeded 22%, offering possibilities for wearable energy. However, phase separation caused by ion migration, instability under humid / light / thermal conditions, and the environmental risks posed by lead still constrain their commercialization. With their superior photoelectric conversion efficiency, perovskite solar cells have become highly promising competitors in the photovoltaic application field.

[0003] Studies have shown that the crystal quality and preferred orientation of perovskite thin films are closely related to their photoelectric properties. Large-size or long-chain ammonium salts play an important role in controlling crystal orientation and constructing effective 2D / 3D heterojunctions. However, while the two-dimensional perovskite passivation layer formed by organic cationic ammonium salts improves the oxygen resistance of devices, it also affects charge transport and recombination processes, leading to a decrease in open-circuit voltage and fill factor. Organic ammonium salt cations, especially aromatic alkyl ammonium salts represented by phenylethyl ammonium iodide (PEAI), play a multifunctional role in perovskite solar cells that far exceeds that of simple additives. Their core function stems from the ammonium ion (-NH3). + The size and charge matching of [A]-site cations in the perovskite lattice, and the additional chemical functions conferred by the organic framework, are key factors. From a physicochemical perspective, the introduction of these molecules directly addresses two core challenges of perovskite materials: those arising from lattice defects (such as lead vacancies V_Pb, iodine vacancies V_I, and uncoordinated lead ions Pb). 0 Non-radiative recombination losses caused by ions, as well as material degradation caused by ion migration and moisture erosion. Taking PEAI as an example, its mechanism of action is a multi-level synergistic process. At the most basic level of chemical passivation, the ammonium group (-NH3) in the PEA⁺ cation... + ) can interact with negatively charged halogen vacancies (such as V_I) on the surface / grain boundaries of perovskites. + Through electrostatic interactions, it effectively neutralizes its charge; simultaneously, the π electron cloud on its benzene ring can bind with exposed, Lewis acidic uncoordinated Pb. 2+Ions coordinate to form stable Pb-π complexes, thereby simultaneously passivating electronic and ionic defects. However, their molecular function is relatively singular, and the resulting two-dimensional phase may grow disorderly, presenting an inherent balance problem between passivation and charge transport.

[0004] Precursor doping can effectively construct bulk 2D / 3D heterojunctions and control orientation, but the passivation molecules are uniformly distributed in the bulk phase, which is not direct or effective enough for passivating defects at the upper interface, and may affect crystallization kinetics. Post-treatment or anti-solvent engineering routes can act directly on the surface, but are difficult to effectively improve the bulk grain orientation and may introduce the risk of solvent erosion. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a three-dimensional molecularly co-passivated perovskite solar cell and its fabrication method.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution: One objective of this invention is to provide a three-dimensional molecularly co-passivated perovskite solar cell, which is composed of a multilayer thin film structure. The perovskite solar cell has a pin structure and consists of, from bottom to top, a transparent ITO conductive glass substrate, a hole transport layer, a buried passivation layer, a perovskite light-absorbing layer, an upper interface passivation layer, an electron transport layer, a physical isolation layer, and a metal electrode layer. The buried passivation layer is a 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide DMBI-I thin film layer spin-coated on the surface of the hole transport layer. During the spin-coating of the perovskite light-absorbing layer, the perovskite precursor solution is doped with 2-thiophene ethyl ammonium iodide TEAI. The upper interface passivation layer is a 4-Meo-PEAI thin film layer spin-coated on the surface of the perovskite light-absorbing layer.

[0007] Preferably, the hole transport layer is a Me-4PACz thin film layer spin-coated on the surface of an ITO electrode on a transparent ITO conductive glass substrate, and the thickness of the hole transport layer is 4-6 nm.

[0008] Preferably, the thickness of the buried passivation layer is 1-2 nm.

[0009] Preferably, the thickness of the perovskite light-absorbing layer is 400-500 nm.

[0010] Preferably, the thickness of the upper interface passivation layer is 3-5 nm.

[0011] Preferably, the electron transport layer is a [6,6]-phenyl-C61-butyrate methyl PCBM thin film layer spin-coated on the surface of the upper interface passivation layer, and the thickness of the electron transport layer is 30-50 nm.

[0012] Preferably, the physical isolation layer is a dimethyl-4,7-diphenyl-1,10-phenanthroline BCP thin film layer spin-coated on the surface of the electron transport layer, and the thickness of the physical isolation layer is 1-2 nm.

[0013] Preferably, the metal electrode layer is a copper electrode deposited on the surface of the physical isolation layer, and the thickness of the metal electrode layer is 95-105 nm.

[0014] The second objective of this invention is to provide a method for preparing the above-mentioned three-dimensional molecularly co-passivated perovskite solar cell, comprising the following steps: S1. The transparent ITO conductive glass substrate is ultrasonically cleaned in ultrapure water, acetone, ethanol and isopropanol in sequence and then dried. S2. Dissolve MeO-4Pacz in anhydrous DMF to prepare a MeO-4Pacz solution with a concentration of 3.0 mg / mL. Spin-coat the MeO-4Pacz solution onto the surface of a dried transparent ITO conductive glass substrate in a glove box filled with nitrogen. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form a hole transport layer. S3. Dissolve 0.5 mg of 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide DMBI-I in 1 mL of anhydrous isopropanol to obtain a DMBI-I solution. Spin-coat the DMBI-I solution onto the surface of the hole transport layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form a buried passivation layer. S4. 615.24 mg of PbI2, 211.87 mg of FAI, 35.97 mg of PbBr2, 10.97 mg of MABr, 18.18 mg of CsI, 3.11 mg of PbCl2 and 2 mg of 2-thiopheneethylammonium iodide (TEAI) were dissolved in a mixed solvent of 800 μL DMF and 200 μL DMSO to obtain a perovskite precursor solution. The perovskite precursor solution was spin-coated onto the surface of the buried passivation layer in a nitrogen-filled glove box to form a perovskite film. The film was then annealed at 100 °C for 10 minutes and cooled to room temperature to form a perovskite light-absorbing layer. S5. Dissolve 1-3 mg of 4-Meo-PEAI in 1 mL of anhydrous isopropanol to obtain a MeO-4Pacz solution. Spin-coat the MeO-4Pacz solution onto the surface of the perovskite light-absorbing layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form an upper interface passivation layer. S6. Dissolve 20 mg of methyl [6,6]-phenyl-C61-butyrate PCBM in 1 mL of chlorobenzene to obtain a PCBM solution. Spin-coat 30 μL of the PCBM solution onto the surface of the upper interface passivation layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form an electron transport layer. S7. A 4 nm dimethyl-4,7-diphenyl-1,10-phenanthroline BCP film layer was deposited onto the surface of the electron transport layer by thermal evaporation under high vacuum to form a physical isolation layer. S8. Finally, a copper electrode is deposited on the upper surface of the physical isolation layer to form a metal electrode layer; thus, a perovskite solar cell is obtained.

[0015] Furthermore, in step S4, the perovskite precursor solution is spin-coated onto the surface of the buried passivation layer using a two-step method: the first step is to spin-coat at 2000 rpm for 10 seconds; the second step is to spin-coat at 4000 rpm for 30 seconds, and 20 seconds into the second step, 100 μL of chlorobenzene is dropped onto the rotating surface of the buried passivation layer as an antisolvent.

[0016] This invention introduces 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide (DMBI-I), 2-thiopheneethylamine ammonium iodide (TEAI), and 4-methoxyphenylethyl ammonium iodide (4-MeO-PEAI) to design a three-dimensional gradient passivation architecture of "buried interface-bulk phase-upper interface" in the vertical spatial dimension of perovskite solar cells. This system systematically and collaboratively solves a series of interrelated bottleneck problems, from interfacial chemical instability and bulk defect recombination to poor surface charge extraction.

[0017] The cationic moiety of DMBI-I is 1,3-dimethylbenzimidazole-onium, whose core is a planar π-conjugated benzimidazole ring. The two nitrogen atoms on this ring are quaternized with methyl groups, forming a positively charged electron-deficient center. Its structural essence is a stable N-heterocyclic carbene precursor salt. During the thermal annealing process of perovskite film post-treatment, a highly reactive carbene species can dissociate in situ at its C2 position, acting as a super-strong Lewis base, reacting with uncoordinated Pb on the perovskite surface or at grain boundaries. 2+The dangling bonds exhibit specific strong coordination interactions, forming stable coordination bonds that effectively passivate deep-level defects. Simultaneously, its planar rigid aromatic structure, through intermolecular π-π stacking interactions, can self-assemble into a dense, ordered, and highly covered two-dimensional ultrathin molecular layer on the perovskite surface. This molecular layer, on the one hand, constructs an effective physical barrier through its hydrophobic benzene rings and methyl groups, significantly inhibiting the erosion of the perovskite lattice by water and oxygen molecules in the environment, thus improving the environmental and phase stability of the device. On the other hand, this ordered two-dimensional structure and its molecular dipoles can optimize the interface energy level alignment between the perovskite and the upper charge transport layer, reducing energy loss at the interface and promoting the extraction and transport of photogenerated carriers while suppressing nonradiative recombination at the interface. Furthermore, its iodide anions can also participate in interfacial interactions, partially compensating for halogen vacancies. In summary, this synergistic effect, stemming from its unique functional group structure and properties, ultimately manifests in device performance as a significant increase in open-circuit voltage, an improvement in fill factor, and a reduction in hysteresis effect, thereby jointly promoting a comprehensive improvement in the photoelectric conversion efficiency and long-term operational stability of perovskite solar cells.

[0018] In the bulk region, TEAI plays the role of a highly efficient defect trapper, its molecular design cleverly integrating the sulfur (S) coordination site of the thiophene ring with the terminal ammonium ion (-NH3). + This achieves a two-site synergistic passivation mechanism: the sulfur atom on the thiophene ring acts as a strong Lewis base, which can react with uncoordinated Pb. 2+ A strong Pb-S coordination bond is formed, while the ammonium ion effectively neutralizes negatively charged halogen vacancies (such as V_I) through electrostatic interactions. + This dual effect of "chemical coordination" and "electrostatic neutralization" can significantly reduce the defect state density of the bulk phase and grain boundaries, suppress nonradiative recombination, and lay the foundation for improving the open-circuit voltage (V_oc) of the device.

[0019] At the top interface of perovskite solar cells, the introduction of 4-MeO-PEAI primarily optimizes surface crystallinity and energy level alignment. In 4-MeO-PEAI (p-methoxyphenylethyl ammonium iodide), the methoxy group (-OCH3) is a strong electron-donating group, significantly increasing the electron cloud density of the benzene ring through resonance and inductive effects. This enhances the benzene ring's ability to act as an electron donor, facilitating interaction with Lewis acidic sites on the perovskite surface (such as uncoordinated Pb). 2+The coordination effect of ) is more effective and stable, thus more effectively reducing the defect state density. This usually manifests as a higher open-circuit voltage (V_oc) in devices. The introduction of methoxy groups may affect the molecular alignment and self-assembly behavior at the crystallization front through weak intermolecular interactions (such as hydrogen bonds or dipole interactions). This helps guide perovskite grains to preferentially grow along specific directions (such as out-of-plane (001)), forming crystallographic orientations that are more conducive to vertical charge transport, thereby improving the fill factor (FF).

[0020] In summary, DMBI-I, TEAI, and 4-MeO-PEAI play irreplaceable roles in three key aspects: intrinsic stability of the interface, broad-spectrum passivation of bulk defects, and optimization of surface charge transport dynamics. They are not simply superimposed, but rather spatially gradient-distributed and functionally deeply coupled, together forming a synergistic system that transcends single or dual passivation strategies. This provides a complete, albeit non-obvious, solution with great potential for implementation, to simultaneously overcome the efficiency and long-term stability bottlenecks of perovskite solar cells. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the perovskite solar cell device structure of the present invention.

[0022] Figure 2 Scanning electron microscope images of the control sample and perovskite films treated with 1 mg, 2 mg, and 3 mg of 4-MeO-PEAI under imidazole / thiophene cation modification.

[0023] Figure 3 X-ray diffraction patterns of perovskite films on transparent ITO conductive glass substrates under imidazole / thiophene cation modification, control samples, and different concentrations of 4-MeO-PEAI treatment were analyzed.

[0024] Figure 4 The absorption spectra are those of the control sample and perovskite films treated with 1 mg, 2 mg, and 3 mg of 4-MeO-PEAI under imidazole / thiophene cation modification.

[0025] Figure 5 The steady-state fluorescence spectra are those of the control sample and perovskite films treated with 1 mg, 2 mg, and 3 mg of 4-MeO-PEAI under imidazole / thiophene cation modification.

[0026] Figure 6The current density-voltage characteristic curves of perovskite solar cell devices with three-dimensional synergistic modification of imidazole / thiophene / methoxy organic ammonium salt and unmodified perovskite solar cell devices are measured in the reverse and forward scanning directions: (a) Current density-voltage characteristic curve in the reverse scanning direction; (b) Current density-voltage characteristic curve in the forward scanning direction.

[0027] Figure 7 The water contact angle of different perovskite films changes with increasing organic ammonium salt concentration gradient. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0029] Example 1: As Figure 1 As shown in the figure, this embodiment exemplarily demonstrates a three-dimensional molecularly co-passivated perovskite solar cell, which is composed of a multilayer thin film structure. This perovskite solar cell has a pin structure, consisting of, from bottom to top, a transparent ITO conductive glass substrate 1, a hole transport layer 2, a buried passivation layer 3, a perovskite light-absorbing layer 4, an upper interface passivation layer 5, an electron transport layer 6, a physical isolation layer 7, and a metal electrode layer 8. The buried passivation layer is a 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide ammonium DMBI-I thin film layer spin-coated onto the surface of the hole transport layer. During spin-coating of the perovskite light-absorbing layer, the perovskite precursor solution is doped with 2-thiophene ethyl ammonium iodide TEAI. The upper interface passivation layer is a 4-Meo-PEAI thin film layer spin-coated onto the surface of the perovskite light-absorbing layer. Hole transport layer 2 is a Me-4PACz thin film layer spin-coated on the surface of the ITO electrode on a transparent ITO conductive glass substrate, with a hole transport layer thickness of 5 nm; the buried passivation layer has a thickness of 2 nm; the perovskite light-absorbing layer has a thickness of 450 nm; the upper interface passivation layer has a thickness of 4 nm; the electron transport layer is a [6,6]-phenyl-C61-butyrate methyl PCBM thin film layer spin-coated on the surface of the upper interface passivation layer, with an electron transport layer thickness of 40 nm; the physical isolation layer is a dimethyl-4,7-diphenyl-1,10-phenanthroline BCP thin film layer spin-coated on the surface of the electron transport layer, with a physical isolation layer thickness of 2 nm; the metal electrode layer is a copper electrode deposited on the surface of the physical isolation layer, with a metal electrode layer thickness of 100 nm.

[0030] Example 2: Based on the perovskite solar cell structure of Example 1, this example provides an exemplary method for fabricating a three-dimensional molecularly co-passivated perovskite solar cell, including the following steps: S1. The transparent ITO conductive glass substrate is ultrasonically cleaned in ultrapure water, acetone, ethanol and isopropanol in sequence and then dried. S2. Dissolve MeO-4Pacz in anhydrous DMF to prepare a MeO-4Pacz solution with a concentration of 3.0 mg / mL. Spin-coat the MeO-4Pacz solution onto the surface of a dried transparent ITO conductive glass substrate in a glove box filled with nitrogen. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form a hole transport layer. S3. Dissolve 0.5 mg of 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide DMBI-I in 1 mL of anhydrous isopropanol to obtain a DMBI-I solution. Spin-coat the DMBI-I solution onto the surface of the hole transport layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form a buried passivation layer. S4. Dissolve 615.24 mg of PbI2, 211.87 mg of FAI, 35.97 mg of PbBr2, 10.97 mg of MABr, 18.18 mg of CsI, 3.11 mg of PbCl2, and 2 mg of 2-thiopheneethylammonium iodide (TEAI) in a mixed solvent of 800 μL DMF and 200 μL DMSO to obtain a perovskite precursor solution. Drop 40 μL of the perovskite precursor solution onto the surface of the buried passivation layer and immediately start a spin-coating program using a two-step method: first, spin at 2000 rpm for 3 seconds, and second, spin at 4000 rpm for 30 seconds. About 20 seconds into the second step, drop 100 μL of chlorobenzene (as an antisolvent) onto the rotating surface of the buried passivation layer. After the second step is completed, a perovskite film is formed. The resulting film is annealed at 100 °C for 10 minutes and cooled to room temperature to form a perovskite light-absorbing layer. S5. Dissolve 1 mg, 2 mg, and 3 mg of 4-Meo-PEAI in 1 mL of anhydrous isopropanol to obtain MeO-4Pacz solution. Spin-coat the MeO-4Pacz solution onto the surface of the perovskite light-absorbing layer in a glove box filled with nitrogen. Then anneal the film at 100°C for 10 minutes and cool it to room temperature to form the upper interface passivation layer. S6. Dissolve 20 mg of methyl [6,6]-phenyl-C61-butyrate PCBM in 1 mL of chlorobenzene to obtain a PCBM solution. Spin-coat 30 μL of the PCBM solution onto the surface of the upper interface passivation layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form an electron transport layer. S7. A 4 nm dimethyl-4,7-diphenyl-1,10-phenanthroline BCP film layer was deposited onto the surface of the electron transport layer by thermal evaporation under high vacuum to form a physical isolation layer. S8. Finally, a copper electrode with a thickness of 100 nm is deposited on the upper surface of the physical isolation layer to form a metal electrode layer; the perovskite solar cell is finally obtained, with an effective area of ​​0.05 cm². 2 .

[0031] Comparative Example 1: S1, A transparent ITO conductive glass substrate was ultrasonically cleaned in ultrapure water, acetone, ethanol and isopropanol in sequence and then dried. S2. Dissolve MeO-4Pacz in anhydrous DMF to prepare a MeO-4Pacz solution with a concentration of 3.0 mg / mL. Spin-coat the MeO-4Pacz solution onto the surface of a dried transparent ITO conductive glass substrate in a nitrogen-filled glove box. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form a hole transport layer with a thickness of 5 nm. S3. Dissolve 615.24 mg of PbI2, 211.87 mg of FAI, 35.97 mg of PbBr2, 10.97 mg of MABr, 18.18 mg of CsI, and 3.11 mg of PbCl2 in a mixed solvent of 800 μL DMF and 200 μL DMSO to obtain a perovskite precursor solution. Drop 40 μL of the perovskite precursor solution onto the surface of the buried passivation layer and immediately start a spin-coating program using a two-step method: the first step is to spin at 2000 rpm for 3 seconds, and the second step is to spin at 4000 rpm for 30 seconds. About 20 seconds into the second step, drop 100 μL of chlorobenzene (as an antisolvent) onto the spinning surface of the buried passivation layer. After the second step is completed, a perovskite film is formed. The resulting film is annealed at 100 °C for 10 minutes and cooled to room temperature to form a perovskite light-absorbing layer with a thickness of 450 nm. S4. Dissolve 20 mg of methyl [6,6]-phenyl-C61-butyrate PCBM in 1 mL of chlorobenzene to obtain a PCBM solution. Spin-coat 30 μL of the PCBM solution onto the surface of the upper interface passivation layer in a nitrogen-filled glove box. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form an electron transport layer with a thickness of 40 nm. S5. A 4 nm dimethyl-4,7-diphenyl-1,10-phenanthroline BCP film layer was deposited onto the surface of the electron transport layer under high vacuum by thermal evaporation to form a 2 nm thick physical isolation layer. S6. Finally, a copper electrode with a thickness of 100 nm is deposited on the upper surface of the physical isolation layer to form a metal electrode layer; the perovskite solar cell is finally obtained, with an effective area of ​​0.05 cm². 2 .

[0032] To investigate the influence of ligand structure on the morphology of 2D / 3D perovskite films, scanning electron microscopy (SEM) was performed on the films before and after the deposition of the iodide spacer layer in this embodiment. Figure 2 The cross-sectional microstructure analysis of the 4-MeO-PEAI modified film and the baseline 3D structure under imidazole / thiophene cation dual passivation reveals the crystallization mode of the perovskite surface under different doping concentrations. Figure 2 As shown, the perovskite grains are tightly connected, indicating good film quality. It is clearly observed that with increasing doping concentration, the perovskite grain size slightly increases, and the grain boundary interstices become more compact. Simultaneously, the content of the white two-dimensional perovskite phase also increases – its organic layer acts as a protective barrier, effectively preventing moisture or ion erosion.

[0033] The XRD patterns of the control group and the perovskite film treated with 4-MeO-PEAI are as follows: Figure 3 As shown. From Figure 3 It can be observed that the control group film has obvious lead iodide and δ phase perovskite diffraction peaks; while after doping treatment, the intensity of the diffraction peaks of both phases is significantly reduced.

[0034] like Figure 4 As shown, the UV-Vis absorption spectra of the control group 3D film and the ligand-modified films with ligand concentrations of 1, 2, and 3 mg / mL indicate that all samples exhibit similar absorption characteristics. The results suggest that 4-MeO-PEAI passivation has a certain impact on the light absorption properties of perovskite films. The film with a ligand concentration of 2 mg / mL exhibits the highest light absorption efficiency, which to some extent confirms the experimental result that the device achieves optimal efficiency at this concentration.

[0035] To investigate the effect of 4-MeO-PEAI on the three-dimensional synergistic passivation with two other cations in perovskites, we performed steady-state photoluminescence (PL) measurements. Figure 5 As shown, compared with the control group films (all samples were spin-coated onto a glass substrate), the films doped with different masses of 4-MeO-PEAI at the perovskite upper interface exhibited significantly enhanced emission peak intensities. This indicates that the synergistic effect of the three-dimensional passivation of the buried interface / bulk phase / upper interface in the perovskite effectively suppresses nonradiative recombination in the perovskite, thereby improving the luminescence intensity of the material.

[0036] We conducted a systematic evaluation of the cell performance (including photovoltaic characteristics). The photovoltaic device was fabricated using a pin structure, specifically composed of: indium tin oxide (ITO) / MeO-4Pacz / perovskite / PCBM / BCP / Cu. The JV curves of the perovskite solar cell device under various conditions are shown below. Figure 6 As shown. The control group perovskite solar cell device achieved an optimal power conversion efficiency (PCE) of 24.7%, an open-circuit voltage (Voc) of 1.20 V, and a short-circuit current density (Jsc) of 25.07 mA / cm². 2 The fill factor (FF) is 82.1%.

[0037] As the ligand concentration increases, the higher content of the two-dimensional perovskite weakens the charge extraction capability, leading to a decrease in the device's PCE. The performance of perovskite solar cells with 4-MeO-PEAI-doped perovskite films peaks at a 4-MeO-PEAI ligand concentration of approximately 2 mg / mL. Generally, at lower organic ligand concentrations, incomplete coverage of the upper interface's two-dimensional capping layer and the phase transition of the 3D heterostructure limit the passivation effect; conversely, excessive ligands lead to the formation of a thick two-dimensional perovskite layer, adversely affecting the charge transport performance at the heterojunction interface and thus reducing device efficiency.

[0038] The highest PCE of the control group was 21.9%, while the 24.7% PCE value is one of the highest efficiencies reported to date for perovskite solar cells using 4-MeO-PEAI. Although the 2 mg / mL doped device achieved a high reverse scan efficiency of 24.7%, a slight bulge appeared at the end of its IV curve. This is because excessive organic ammonium salt doping promotes the formation of excessive two-dimensional perovskite on the upper surface, leading to charge transport instability. Therefore, for the 3 mg / mL doped device, not only was the bulge more pronounced, but the current density also decreased significantly, thus failing to obtain a high-efficiency device.

[0039] Finally, one advantage of introducing hydrophobic organic ligands is that they can enhance the water resistance of perovskite films; for this purpose, we conducted contact angle tests. For example... Figure 7 As shown, compared to the 61° water contact angle of the control film, the modified film exhibits a water contact angle improvement of 4.2°–7.8°. This improvement is primarily attributed to the more regular quantum well orientation and the introduction of organic ligand doping into the perovskite solution and at the upper interface. The hydrophobic two-dimensional perovskite phase distributed at the upper interface and within the perovskite crystal effectively blocks water penetration, delaying the undesirable phase transition from the α phase to the inactive δ phase in FA / MA-based perovskites. In contrast, the water contact angle of the control film is only 61°.

[0040] In summary, DMBI-I, TEAI, and 4-MeO-PEAI play irreplaceable roles in three key aspects: intrinsic stability of the interface, broad-spectrum passivation of bulk defects, and optimization of surface charge transport dynamics. They are not simply superimposed, but rather spatially gradient-distributed and functionally deeply coupled, together forming a synergistic system that transcends single or dual passivation strategies. This provides a complete, albeit non-obvious, solution with great potential for implementation, to simultaneously overcome the efficiency and long-term stability bottlenecks of perovskite solar cells.

[0041] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A three-dimensional molecularly co-passivated perovskite solar cell, composed of a multilayer thin film structure, characterized in that: The perovskite solar cell has a pin structure, consisting of a transparent ITO conductive glass substrate, a hole transport layer, a buried passivation layer, a perovskite light-absorbing layer, an upper interface passivation layer, an electron transport layer, a physical isolation layer, and a metal electrode layer from bottom to top. The buried passivation layer is a 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide DMBI-I thin film layer spin-coated on the surface of the hole transport layer. During the spin-coating of the perovskite light-absorbing layer, the perovskite precursor solution is doped with 2-thiophene ethyl ammonium iodide TEAI. The upper interface passivation layer is a 4-Meo-PEAI thin film layer spin-coated on the surface of the perovskite light-absorbing layer.

2. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The hole transport layer is a Me-4PACz thin film layer spin-coated on the surface of the ITO electrode on a transparent ITO conductive glass substrate, and the thickness of the hole transport layer is 4-6 nm.

3. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The thickness of the buried passivation layer is 1-2 nm.

4. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The thickness of the perovskite light-absorbing layer is 400-500 nm.

5. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The thickness of the passivation layer at the upper interface is 3-5 nm.

6. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The electron transport layer is a [6,6]-phenyl-C61-butyrate methyl PCBM thin film layer spin-coated on the surface of the upper interface passivation layer, and the thickness of the electron transport layer is 30-50 nm.

7. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The physical isolation layer is a dimethyl-4,7-diphenyl-1,10-phenanthroline BCP thin film layer spin-coated on the surface of the electron transport layer, and the thickness of the physical isolation layer is 1-2 nm.

8. The three-dimensional molecularly co-passivated perovskite solar cell according to claim 1, characterized in that: The metal electrode layer is a copper electrode deposited on the surface of the physical isolation layer, and the thickness of the metal electrode layer is 95-105 nm.

9. A method for preparing a three-dimensional molecularly co-passivated perovskite solar cell as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The transparent ITO conductive glass substrate is ultrasonically cleaned in ultrapure water, acetone, ethanol and isopropanol in sequence and then dried. S2. Dissolve MeO-4Pacz in anhydrous DMF to prepare a MeO-4Pacz solution with a concentration of 3.0 mg / mL. Spin-coat the MeO-4Pacz solution onto the surface of a dried transparent ITO conductive glass substrate in a glove box filled with nitrogen. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form a hole transport layer. S3. Dissolve 0.5 mg of 1,3-dimethyl-1H-benzo[d]imidazolium-3-iodide DMBI-I in 1 mL of anhydrous isopropanol to obtain a DMBI-I solution. Spin-coat the DMBI-I solution onto the surface of the hole transport layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form a buried passivation layer. S4. 615.24 mg of PbI2, 211.87 mg of FAI, 35.97 mg of PbBr2, 10.97 mg of MABr, 18.18 mg of CsI, 3.11 mg of PbCl2 and 2 mg of 2-thiopheneethylammonium iodide (TEAI) were dissolved in a mixed solvent of 800 μL DMF and 200 μL LDMSO to obtain a perovskite precursor solution. The perovskite precursor solution was spin-coated onto the surface of the buried passivation layer in a nitrogen-filled glove box to form a perovskite film. The film was then annealed at 100 °C for 10 minutes and cooled to room temperature to form a perovskite light-absorbing layer. S5. Dissolve 1-3 mg of 4-Meo-PEAI in 1 mL of anhydrous isopropanol to obtain a MeO-4Pacz solution. Spin-coat the MeO-4Pacz solution onto the surface of the perovskite light-absorbing layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 10 minutes and cool it to room temperature to form an upper interface passivation layer. S6. Dissolve 20 mg of methyl [6,6]-phenyl-C61-butyrate PCBM in 1 mL of chlorobenzene to obtain a PCBM solution. Spin-coat 30 μL of the PCBM solution onto the surface of the upper interface passivation layer in a glove box filled with nitrogen. Then anneal the film at 100 °C for 5 minutes and cool it to room temperature to form an electron transport layer. S7. A 4 nm dimethyl-4,7-diphenyl-1,10-phenanthroline BCP film layer was deposited onto the surface of the electron transport layer by thermal evaporation under high vacuum to form a physical isolation layer. S8. Finally, a copper electrode is deposited on the upper surface of the physical isolation layer to form a metal electrode layer; thus, a perovskite solar cell is obtained.

10. The method for preparing a three-dimensional molecularly co-passivated perovskite solar cell according to claim 9, characterized in that, In step S4, the perovskite precursor solution is spin-coated onto the surface of the buried passivation layer using a two-step method: Step 1: Spin-coat at 2000 rpm for 10 seconds; Step 2: Spin coat at 4000 rpm for 30 seconds, and 20 seconds into the second step, drop 100 μL of chlorobenzene as an antisolvent onto the surface of the spinning buried passivation layer.

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