Perovskite solar cell and preparation method thereof

Abstract

The application relates to the technical field of solar cells, in particular to a perovskite solar cell and a preparation method thereof. The cell is a planar reverse structure, and comprises a substrate, a hole transport layer, a perovskite active layer, a passivation layer, an electron transport layer and an electrode which are sequentially stacked. The passivation layer comprises a first passivation molecule 4,4',4"-phosphoryltriphenylcarboxylic acid (TCPPO) and a second passivation molecule 1,3-propylenediamine dihydroiodide (PDAI2). The two passivation molecules realize comprehensive passivation and energy level adjustment of the interface defects of the perovskite active layer through synergistic effect of chemical passivation and field effect passivation. The preparation method adopts a one-step anti-solvent method to prepare the perovskite active layer, and a double-molecule passivation solution is spin-coated on the perovskite active layer to form the passivation layer. Through the double-molecule synergistic passivation strategy, the application effectively reduces the interface non-radiative recombination loss, optimizes the carrier transport efficiency, and thus obtains a high-efficiency and stable reverse perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a perovskite solar cell and its fabrication method. Background Technology

[0002] Energy is the core support for human social development. The non-renewable nature of traditional fossil fuels and the greenhouse gases and pollutants generated during their use not only lead to the depletion of energy reserves but also trigger a series of problems such as global climate imbalance and increased public health burden. Developing and utilizing clean and renewable energy has become crucial for achieving sustainable development. Solar energy, due to its inexhaustible availability, wide distribution, and low maintenance costs, has become an important choice for clean energy. Photovoltaic power generation, as the core form of solar energy utilization, has broad application prospects in various fields.

[0003] Solar cell technology has undergone three generations of development. The first generation of crystalline silicon solar cells dominated the market, but had shortcomings such as high investment costs, complex production processes, high energy consumption in raw material processing, and heavy pollution. The second generation of multi-component compound thin-film photovoltaic devices was limited by rare metal materials, resulting in high costs, difficulty in mass production, and insufficient stability. The third generation of perovskite solar cells has become a research hotspot in the photovoltaic field due to its advantages such as rapidly improving photoelectric conversion efficiency (reaching 27.3% in more than ten years) and flexible fabrication processes. Its crystal structure with the general chemical formula ABX3 has rich diversity and tunability, making it a highly promising semiconductor material.

[0004] Perovskite solar cells are classified into mesoporous and planar structures. Among them, the planar inverted structure (pin) is more suitable for industrialization due to its advantages such as high efficiency, good stability, low-temperature processing capability, and compatibility with tandem cell fabrication. However, the current research and development of inverted perovskite solar cells still faces key scientific challenges: there is significant energy loss at the interface between the perovskite and the electron transport layer, and existing passivation methods have obvious defects—organohaloammonium salts easily induce two-dimensional perovskite phases when passivating defects; while field-effect passivation with short-chain amine ligands can improve electron extraction efficiency, it cannot comprehensively solve the interface defect problem; traditional single passivation molecules rely solely on group coordination to achieve defect passivation, resulting in incomplete defect coverage, especially with limited passivation effect on iodine vacancy defects. This leads to poor crystallinity of the perovskite film and a high probability of nonradiative recombination of interfacial carriers, ultimately affecting the photoelectric conversion efficiency and long-term operational stability of the device.

[0005] The purpose of this invention is to design a novel passivation molecule, 4,4',4"-phosphoryltribenzoic acid (TCPPO), and combine it with 1,3-propanediamine dihydroiodate (PDAI2) to construct a bimolecular passivation system. This system addresses the technical problems of incomplete passivation of interface defects and large energy loss in existing invert perovskite solar cells. Through synergistic chemical passivation and field-effect passivation, the crystal quality and interface performance of the perovskite film are comprehensively optimized, and the carrier transport and extraction efficiency is improved, thereby preparing a highly efficient and stable invert perovskite solar cell. The invention also provides a corresponding preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a perovskite solar cell and its preparation method, which uses TCPPO and PDAI2 to construct a bimolecular passivation layer, and improves the device efficiency and stability through the synergistic effect of chemical passivation and field-effect passivation.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A perovskite solar cell, wherein the perovskite solar cell has a planar inverted structure, comprising, in sequence, a substrate, a hole transport layer, a perovskite active layer, a passivation layer, an electron transport layer, and an electrode; The passivation layer comprises a first passivation molecule and a second passivation molecule. The first passivation molecule and the second passivation molecule work synergistically through chemical passivation and field-effect passivation to passivate defects and regulate energy levels in the perovskite active layer.

[0008] Furthermore, the first passivation molecule is an organic small molecule with a phosphorus-oxygen double bond group and at least two carboxyl groups, used to coordinate and bind to various defect sites in the perovskite material; the second passivation molecule is an organic diamine hydrohalate, used to adjust the energy level matching between the perovskite active layer and the electron transport layer.

[0009] Furthermore, the first passivating molecule is 4,4',4"-phosphoryltribenzoic acid, and the second passivating molecule is 1,3-propanediamine dihydroiodate.

[0010] Furthermore, the hole transport layer is an inorganic metal oxide hole transport layer; and / or The material of the inorganic metal oxide hole transport layer is nickel oxide.

[0011] Furthermore, an interface modification layer is disposed between the hole transport layer and the perovskite active layer; the interface modification layer is an organic small molecule self-assembled monolayer material; and / or The organic small molecule self-assembled monolayer material is MeO-2PACz.

[0012] Furthermore, the material of the perovskite active layer is ABX3 type perovskite material, wherein the A site is an organic cation, an inorganic cation, or a combination of both, the B site is a divalent metal cation, and the X site is a halide anion.

[0013] On the other hand, the present invention proposes a method for preparing the above-mentioned perovskite solar cell, comprising the following steps: A hole transport layer is formed on the substrate; A perovskite precursor solution is applied to the hole transport layer, and an antisolvent is introduced during the film formation process to regulate the crystallization process. After annealing, a perovskite active layer is formed. A passivation solution containing a first passivation molecule and a second passivation molecule is prepared, wherein the mass ratio of the first passivation molecule to the second passivation molecule is 1:10, and the solvent of the passivation solution is an organic alcohol solvent. The passivation solution is applied to the perovskite active layer, and the passivation layer is formed by annealing. An electron transport layer is deposited on the passivation layer; Electrodes are formed on the electron transport layer.

[0014] Furthermore, the antisolvent is chlorobenzene; and / or The solvent for the perovskite precursor solution is a mixture of dimethylformamide and dimethyl sulfoxide.

[0015] Furthermore, the electron transport layer includes a first electron transport layer and a second electron transport layer; the material of the first electron transport layer is fullerene or its derivative, and the material of the second electron transport layer is copper bath.

[0016] Furthermore, the thickness of the first electron transport layer is 20-30 nanometers, and the thickness of the second electron transport layer is 5-10 nanometers.

[0017] The beneficial effects of this invention are: This invention employs a passivation layer constructed by compounding 4,4',4"-phosphoryltribenzoic acid (TCPPO) and 1,3-propanediamine dihydroiodate (PDAI2) in a 1:10 mass ratio. The TCPPO molecule contains both a phosphorus-oxygen double bond (P=O) and three carboxyl groups (-COOH), both of which are strong Lewis base coordination groups. These groups can form stable coordination bonds with uncoordinated lead ions and deep-level defects such as iodine vacancies in the perovskite lattice, transforming these recombination centers into relatively inert shallow-level defect states. Simultaneously, PDAI2, as an organic diamine hydrohalide, has positively charged ammonium ions that form a dipole layer on the perovskite surface, inducing band bending at the interface. Figure 7The energy level test results further indicate that the combined effect of TCPPO and PDAI2 shifts the semiconductor properties of the perovskite film towards the N-type direction, confirming that the introduction of TCPPO not only enhances the chemical passivation effect but also participates in the rearrangement of interface energy levels. The two passivation mechanisms complement each other at the molecular level: TCPPO achieves broad-spectrum chemical end-capping of various defect sites, while PDAI2 optimizes energy level matching through field effects. Their synergistic effect significantly reduces the density of deep-level defect states at the interface and effectively suppresses the nonradiative recombination probability.

[0018] In this invention, a passivation solution composed of TCPPO and PDAI2 is spin-coated onto the pre-formed perovskite active layer, allowing the passivation molecules to penetrate to the grain boundaries on the perovskite surface. The carboxyl groups in the TCPPO molecules form an intermediate coordination structure with lead ions, inducing secondary recrystallization of the surface grains during annealing, promoting the fusion of small grains and eliminating grain boundaries. Figure 2 and Figure 3 Scanning electron microscopy comparisons showed that the perovskite thin films treated with the TCPPO-PDAI2 bimolecular system exhibited significantly increased grain size and markedly improved film density. Figure 5 The X-ray diffraction pattern further confirms that the characteristic diffraction peaks of the film treated with the bimolecular system are significantly enhanced in intensity and narrowed at half maximum width at half maximum (FWHM), indicating improved crystallinity and more consistent crystal orientation. The improved crystallinity reduces the density of bulk defects within the film and decreases dangling bonds at grain boundaries caused by structural distortion, providing a lower-loss channel for the transport of photogenerated carriers within the perovskite layer.

[0019] Figure 6 Conductivity tests show that the PDAI2 film doped with TCPPO has higher conductivity than the single PDAI2 film. The large conjugated aromatic framework of TCPPO can interact with perovskite and electron transport layer (C 60 This forms an effective electronic coupling, creating a continuous electronic transport channel at the interface. Figure 7 Energy level testing results show that the perovskite film treated with the TCPPO-PDAI2 bimolecular system exhibits more significant N-type semiconductor characteristics. Its Fermi level shifts towards the conduction band, reducing the energy barrier height between the perovskite layer and the electron transport layer, and decreasing the depletion layer width. The optimization of the band structure and the improvement of interface conductivity create a synergistic effect, enabling photogenerated electrons to be efficiently extracted and rapidly injected into the electron transport layer upon reaching the perovskite / electron transport layer interface, avoiding electron accumulation and recombination at the interface. These electrical performance optimizations translate into improved device performance. Figure 4 The simultaneous improvement of short-circuit current density, open-circuit voltage, and fill factor shown ultimately leads to a breakthrough in photoelectric conversion efficiency.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The diagram shows the molecular formula of TCPPO and the structural schematic of the perovskite solar cell of this invention.

[0023] Figure 2 Scanning electron microscope image of a perovskite layer prepared by a conventional method.

[0024] Figure 3 This is a scanning electron microscope image of the perovskite layer containing the TCPPO-PDAI2 bimolecular passivation system of the present invention.

[0025] Figure 4 This is a comparison chart of the JV curves of the perovskite solar cell of the present invention and the conventional perovskite solar cell.

[0026] Figure 5 This is an X-ray diffraction pattern of the perovskite layer containing the TCPPO-PDAI2 bimolecular passivation system of the present invention.

[0027] Figure 6 This invention provides a comparison of the conductivity of the TCPPO-PDAI2 bimolecular passivation system and the single PDAI2 system.

[0028] Figure 7 This diagram shows the positions of the valence and conduction bands of perovskite layers with and without the TCPPO-PDAI2 bimolecular passivation system. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The perovskite solar cell described in this invention is specifically a planar inverted (pin) structure, such as... Figure 1 As shown, from the substrate to the electrode, it includes: an FTO conductive substrate, a NiO electrode, and so on. XHole transport layer, MeO-2PACz modified layer, perovskite active layer, TCPPO-PDAI2 bimolecular passivation layer, C 60 Electron transport layer, BCP electron transport modification layer, Ag metal electrode.

[0031] The perovskite active layer is made of ABX3 type perovskite material, with methylamine ions (MA) at the A-site. + ), formamidinium ion (FA) + ), cesium ions (Cs) + One or more combinations of cations such as lead (Pb) are present at the B site. 2+ ), tin ions (Sn) 2+ The perovskite active layer contains metal cations such as chlorine, bromine, and iodine at the X-position; the core functional layer is the TCPPO-PDAI2 bimolecular passivation layer, which is composed of novel passivation molecule TCPPO and field passivation molecule PDAI2 to achieve comprehensive defect passivation of the perovskite active layer. Example 1

[0032] The present invention provides a method for fabricating inverted perovskite solar cells, which relies on a one-step antisolvent method to prepare high-quality perovskite thin films and combines a bimolecular passivation strategy to optimize interface performance. The specific steps are as follows: FTO conductive substrate pretreatment: The FTO conductive glass was ultrasonically cleaned sequentially with deionized water, acetone and anhydrous ethanol to remove surface impurities, and then subjected to ultraviolet ozone treatment for 20 minutes to improve the hydrophilicity of the substrate surface.

[0033] NiO X Hole transport layer preparation: NiO was prepared by solution spin coating. X The precursor solution was spin-coated onto the pretreated FTO substrate at a spin speed of 2000 rpm for 25 seconds, followed by a spin coating at 120°C. o Annealing at C for 20 minutes forms a dense NiO. X Hole transport layer.

[0034] Preparation of MeO-2PACz modified layer: A MeO-2PACz ethanol solution with a concentration of 0.5 mg / mL was spin-coated onto NiO. X On the hole transport layer, the spin coating speed was 4000 rpm, the spin coating time was 25 seconds, and then it was applied at 100... o Annealing at C for 10 minutes forms a MeO-2PACz modified layer.

[0035] Preparation of the perovskite active layer: Taking a quaternary cationic perovskite component as an example, the perovskite precursor solution is a 1.5M Rb solution. 0.03 Cs 0.05 FA 0.9 MA 0.05PbI3, where FA is NH2CHNH2 + MA is CH3NH3 + The solvent was a mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), with a volume ratio of DMF to DMSO of 4:1. The mixture was stirred for 6 hours. The precursor solution was spin-coated onto the MeO-2PACz modified layer. During the spin-coating process, the antisolvent chlorobenzene was added dropwise to regulate the crystallization process. o Annealing at C for 1 hour forms a perovskite light-absorbing layer.

[0036] Preparation of TCPPO-PDAI2 bimolecular passivation layer: TCPPO and PDAI2 were dissolved in isopropanol at a ratio of 1:10 to prepare a 1 mg / mL bimolecular passivation solution. This solution was then spin-coated onto the perovskite active layer at a spin speed of 4500 rpm for 25 seconds, followed by a 100°C spin coating. o Annealing at C for 10 minutes forms a TCPPO-PDAI2 bimolecular passivation layer.

[0037] C 60 Electron transport layer fabrication: C was deposited on the bimolecular passivation layer using a vacuum thermal evaporation method. 60 The electron transport layer has a thickness controlled at 25 nanometers.

[0038] Preparation of BCP electron transport modification layer: in C 60 A BCP modification layer is then vacuum-deposited onto the electron transport layer, with a thickness controlled at 6 nanometers.

[0039] Ag electrode fabrication: Ag electrodes were deposited on the BCP-modified layer using a vacuum thermal evaporation method, with a thickness controlled at 120 nanometers, thus completing the fabrication of the entire inverted perovskite solar cell.

[0040] Comparative Example The bimolecular passivation layer preparation step was removed, and the remaining preparation steps and process parameters were completely consistent with those in Example 1.

[0041] like Figure 2 and Figure 3 As shown, scanning electron microscopy (SEM) tests revealed that the perovskite film based on the TCPPO-PDAI2 bimolecular passivation system has a larger grain size and a denser morphology.

[0042] Under standard test conditions (AM1.5G illumination), the open-circuit voltage, short-circuit current density, fill factor, photoelectric conversion efficiency, and current-voltage curves of the perovskite solar cells prepared in Example 1 and the comparative example are shown below. Figure 4As shown in the figure, the open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency of the perovskite solar cell prepared by the method of the present invention are significantly higher than those of the comparative perovskite solar cell without the TCPPO-PDAI2 bimolecular passivation system.

[0043] like Figure 5 As shown, perovskite films with different passivation systems were characterized by X-ray diffraction (XRD). The results showed that, compared with the comparative example, the perovskite film prepared by the TCPPO-PDAI2 bimolecular passivation system had significantly improved characteristic diffraction peak intensity, sharper peak shape, and narrower half-width at half-maximum. This indicates that the bimolecular synergistic passivation strategy can effectively promote perovskite grain growth, improve the crystallinity and crystallinity of the film, and is beneficial to obtaining perovskite films with lower defect density and more regular structure.

[0044] like Figure 6 As shown in the IV image, the PDAI2 film with TCPPO doping has higher conductivity.

[0045] like Figure 7 As shown, the perovskite thin film based on the TCPPO-PDAI2 bimolecular passivation system exhibits more significant N-type semiconductor characteristics. This characteristic can effectively enhance the electron transport capability of the thin film and significantly reduce the energy loss at the interface of the perovskite solar cell.

[0046] In summary, this invention proposes a perovskite solar cell and its fabrication method. The cell has a planar inverted structure, comprising a substrate, a hole transport layer, a perovskite active layer, a passivation layer, an electron transport layer, and electrodes stacked sequentially. The passivation layer contains a first passivation molecule, 4,4',4"-phosphoryltribenzoic acid (TCPPO), and a second passivation molecule, 1,3-propanediamine dihydroiodate (PDAI2). Through the synergistic effect of chemical passivation and field-effect passivation, they achieve comprehensive passivation of interface defects in the perovskite active layer and energy level modulation. The fabrication method employs a one-step anti-solvent method to prepare the perovskite active layer, and then spin-coates a bimolecular passivation solution onto it to form the passivation layer. This invention, through a bimolecular synergistic passivation strategy, effectively reduces interfacial nonradiative recombination losses and optimizes carrier transport efficiency, thereby obtaining a highly efficient and stable inverted perovskite solar cell.

[0047] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A perovskite solar cell, characterized in that, The perovskite solar cell has a planar inverted structure, comprising, in sequence, a substrate, a hole transport layer, a perovskite active layer, a passivation layer, an electron transport layer, and an electrode. The passivation layer comprises a first passivation molecule and a second passivation molecule. The first passivation molecule and the second passivation molecule work synergistically through chemical passivation and field-effect passivation to passivate defects and regulate energy levels in the perovskite active layer.

2. The perovskite solar cell as described in claim 1, characterized in that, The first passivation molecule is an organic small molecule with a phosphorus-oxygen double bond group and at least two carboxyl groups, used to coordinate and bind to various defect sites in the perovskite material; the second passivation molecule is an organic diamine hydrohalate, used to adjust the energy level matching between the perovskite active layer and the electron transport layer.

3. The perovskite solar cell as described in claim 2, characterized in that, The first passivating molecule is 4,4',4"-phosphoryltribenzoic acid, and the second passivating molecule is 1,3-propanediamine dihydroiodate.

4. The perovskite solar cell according to claim 1, characterized in that, The hole transport layer is an inorganic metal oxide hole transport layer; and / or The material of the inorganic metal oxide hole transport layer is nickel oxide.

5. The perovskite solar cell according to claim 1, characterized in that, An interface modification layer is further disposed between the hole transport layer and the perovskite active layer; the interface modification layer is a self-assembled monolayer material of small organic molecules; and / or The organic small molecule self-assembled monolayer material is MeO-2PACz.

6. The perovskite solar cell according to claim 1, characterized in that, The perovskite active layer is made of ABX3 type perovskite material, wherein the A site is an organic cation, an inorganic cation, or a combination of both, the B site is a divalent metal cation, and the X site is a halide anion.

7. A method for preparing a perovskite solar cell according to any one of claims 1-6, characterized in that, include: A hole transport layer is formed on the substrate; A perovskite precursor solution is applied to the hole transport layer, and an antisolvent is introduced during the film formation process to regulate the crystallization process. After annealing, a perovskite active layer is formed. A passivation solution containing a first passivation molecule and a second passivation molecule is prepared, wherein the mass ratio of the first passivation molecule to the second passivation molecule is 1:10, and the solvent of the passivation solution is an organic alcohol solvent. The passivation solution is applied to the perovskite active layer, and the passivation layer is formed by annealing. An electron transport layer is deposited on the passivation layer; Electrodes are formed on the electron transport layer.

8. The preparation method according to claim 7, characterized in that, The antisolvent is chlorobenzene; and / or The solvent for the perovskite precursor solution is a mixture of dimethylformamide and dimethyl sulfoxide.

9. The preparation method according to claim 7, characterized in that, The electron transport layer includes a first electron transport layer and a second electron transport layer; the material of the first electron transport layer is fullerene or its derivative, and the material of the second electron transport layer is copper bath.

10. The preparation method according to claim 9, characterized in that, The thickness of the first electron transport layer is 20-30 nanometers, and the thickness of the second electron transport layer is 5-10 nanometers.

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