Preparation method and application of cross-linked polyionic liquid additive material for improving ultraviolet stability and self-repairing capability of perovskite solar cell

Abstract

The application discloses a kind of crosslinking polyionic liquid additive materials for promoting perovskite solar cell ultraviolet stability and self-repairing ability and preparation method and application thereof.The additive is a kind of dynamic crosslinking network polymer, and is formed by 1-vinyl-3-alkyl imidazolium monomer and multi-thiol or double bond crosslinking agent containing disulfide bond copolymerization.It is stabilized by anion, cation and perovskite interface synergistic "ion lock" effect, and passivation defect is significantly inhibited under ultraviolet light ion migration and material decomposition;Meanwhile, dynamic ion aggregate in polymer network and disulfide bond give material efficient self-repairing ability, so that perovskite film doped with the additive can be quickly repaired microcrack under heating of 60-100 DEG C.It is doped in perovskite precursor solution at 0.1-5.0 mg / mL, can simultaneously promote the ultraviolet stability, mechanical flexibility and long-term environmental storage stability of battery, and process compatibility is good, to provide effective solution for preparing high-efficiency, stable perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of polymer optoelectronic materials and new energy technology, specifically relating to a cross-linked polyionic liquid additive material for improving the ultraviolet stability and self-healing ability of perovskite solar cells, its preparation method and application. Background Technology

[0002] Perovskite solar cells have become a frontier in photovoltaic research due to their superior photoelectric conversion efficiency. However, their commercialization faces two major bottlenecks: ultraviolet light stability and mechanical brittleness. First, perovskite materials are extremely sensitive to ultraviolet light. Under ultraviolet photon energy excitation, halide ions (such as I⁻) in the perovskite lattice are easily excited and migrate, leading to the formation of halogen vacancies. These vacancies further react with organic cations (such as MA⁺ and FA⁺) to generate volatile products (such as CH₃NH₂ and HI), triggering irreversible material decomposition. This process severely limits the long-term operating life of devices under outdoor all-weather conditions. Second, the intrinsic weakness of perovskite as an ionic crystal makes it susceptible to microcracks and grain boundary damage under thermal stress, bending, or external pressure. These physical damages are not only a direct cause of efficiency degradation but also provide a rapid pathway for water and oxygen erosion and ion migration, accelerating the overall failure of the device.

[0003] To address these challenges, existing technologies largely employ a "divide and conquer" strategy: 1) using small-molecule UV-absorbing materials for defect passivation to improve UV stability, but these suffer from problems such as easy migration, volatility, and insufficient long-term stability; 2) introducing self-healing elastomers, utilizing their entanglement and toughness to dissipate stress, while simultaneously endowing perovskites with a certain degree of self-healing ability. However, most current research focuses on their single function (such as passivation or self-healing), and no work has yet systematically designed an additive material that can simultaneously and synergistically solve the dual problems of UV photochemical decomposition and physical-mechanical damage.

[0004] This invention focuses on the "ionic liquid lock effect" of synergistic anion-cation interaction in polyionic liquids to enhance UV stability and the multi-level dynamic self-healing mechanism mediated by ion aggregates. It proposes a cross-linked polyionic liquid additive material and its preparation method that can both suppress initial damage under UV excitation through molecular design and rapidly self-repair to restore function after mechanical damage. Based on this novel multifunctional additive material of cross-linked polyionic liquids, it can persistently passivate perovskite interface defects through strong interactions, accelerate the dynamic reversible disulfide bond self-healing ability by introducing polyionic liquids, and form a dense network to block water and oxygen erosion. This is of great significance for improving the stability of perovskite solar cells and promoting their practical application, providing a breakthrough solution for the practical application of perovskite solar cells. Summary of the Invention

[0005] To address the challenges of UV instability and mechanical brittleness in perovskite solar cells, this invention aims to provide a novel cross-linked polyionic liquid additive material and its preparation method. Through unique molecular design, this material simultaneously achieves the following functions within the perovskite active layer: ① "Ionic liquid locking effect": suppressing UV-induced ion migration and material decomposition, significantly improving photochemical stability. ② "Ion aggregate-mediated multi-level dynamic self-healing": rapidly and efficiently repairing microcracks in the thin film under mild thermal stimulation, restoring mechanical integrity and electrical properties.

[0006] The crosslinked polyionic liquid additive material provided by this invention is a dynamic crosslinked network polymer, whose basic structural unit is constructed by free radical polymerization of a polymerizable imidazole-based ionic liquid monomer and a multifunctional crosslinking agent. The cationic portion of the ionic liquid monomer is preferably 1-vinyl-3-alkylimidazolium, and the crosslinking agent is a compound containing multiple thiol groups or carbon-carbon double bonds. If the crosslinking agent [Core] has four thiol groups, it has the following general chemical structural formula (Ⅰ).

[0007]

[0008] General Formula (I)

[0009] In the formula: PIL =

[0010] R = -C a H (2a+1) In the formula, a is an integer from 1 to 18;

[0011] In the formula, X — Selected from F — Cl — ,Br — I — BF 4— PF 6— SCN — , Tf2N⁻, BPh4⁻, HSO4⁻, EtSO4 — TFSI — H2PO4 — CF3COO⁻, CH3COO⁻, OH — One of the amino acid anions;

[0012] [Core] is the crosslinking agent in in-situ crosslinked polymers, and can generally be divided into two types:

[0013] One type is a crosslinking agent containing two or more thiol functional groups, whose [Core] is usually a thiol ester derivative of a polyol (such as pentaerythritol tetrakis(3-mercaptopropionic acid) ester, trimethylolpropane tris(3-mercaptopropionate), glycerol tris(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), etc.); aliphatic dithiol thiol ester derivatives (such as 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1... The following are examples of thioglycolic acid derivatives: 6-hexanedithiol, 1,8-octanedithiol, 1,10-decanedithiol, etc.; thioglycolic acid derivatives of aromatic polythiols (such as 1,4-benzenedithiol, 1,3,5-tris(mercaptomethyl)benzene, tetramercaptobenzene, etc.); thioglycolic compounds containing ether bonds (such as bis(2-mercaptoethyl) ether, 2,2'-(ethylenedioxy)diethylthiol, etc.); and multi-arm polymeric thioglycolic acid derivatives (such as polyethylene glycol dithiol, tetra-arm polyethylene glycol thioglycolic acid, etc.). In this case, the cross-linked polyionic liquid needs to be blended with disulfide-containing thioctic acid as a self-healing additive for perovskite precursor solutions.

[0014] The second type of crosslinking agent is a multi-carbon double bond containing disulfide bonds, usually N,N'-bis(acryloyl)cysteine. In this case, the crosslinked polyionic liquid itself can serve as a self-healing additive for perovskite precursor solutions.

[0015] Furthermore, the preparation method of the above-mentioned ionic liquid crosslinked polymer material with self-healing function includes the following steps:

[0016] An imidazole ionic liquid with vinyl groups is mixed with a crosslinking agent with thiol or vinyl groups, an initiator is added, the mixture is stirred until homogeneous, and the reaction is carried out under heating conditions. After cooling at room temperature, a viscous crosslinked polyionic liquid additive material is obtained.

[0017] Furthermore, the ionic liquid is ethyl 1-vinyl-3-ethylimidazolium sulfate, and the initiator is AIBN.

[0018] Furthermore, when [Core] is a crosslinking agent containing thiol groups, the mass ratio of the ionic liquid to pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 4~5:1, the reaction temperature of the ionic liquid and pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 90°C~110°C, and the reaction time is 10 min~20 min.

[0019] Furthermore, when [Core] is a vinyl-containing crosslinking agent, the mass ratio of ionic liquid to N,N'-bis(acryloyl)cysteine ​​is 2.4~3:1, the reaction temperature of ionic liquid and N,N'-bis(acryloyl)cysteine ​​is 75°C~85°C, and the reaction time is 20min~30min.

[0020] Furthermore, a self-healing and reinforcing composition comprising dynamic disulfide bonds is composed of a cross-linked polyionic liquid additive material and thioctic acid; wherein the mass ratio of the cross-linked polyionic liquid additive material to thioctic acid is (6:5) to (1:1).

[0021] A perovskite solar cell includes a substrate, an electrode layer, a hole transport layer, a perovskite active layer, an electron transport layer, and another electrode, stacked sequentially. The perovskite layer of this invention comprises a cross-linked polyionic liquid additive or a self-healing reinforcing composition doped in a perovskite precursor solution at a doping concentration of 0.1 mg / mL to 5.0 mg / mL. The perovskite active layer possesses physical crack repair capability under heating conditions of 60-100°C. This improves the ultraviolet stability and mechanical durability of the perovskite solar cell.

[0022] The core innovative mechanism of this invention is as follows:

[0023] Mechanism 1: The synergistic "ionic liquid lock-in effect" of anions and cations enhances UV stability.

[0024] The UV stabilizing function of the material in this invention originates from the synergistic effect of its anions and cations:

[0025] Anion-dominant passivation: Anions in the material, especially BF4⁻, PF6⁻, TFSI⁻, and oxygen-containing anions (such as EtSO4⁻, CF3COO⁻), can form strong coordination interactions with uncoordinated Pb²⁺ on the perovskite surface / grain boundaries, directly passivating deep-level defects. Furthermore, the fluorine atoms of fluorine-containing anions (BF4⁻, PF6⁻, TFSI⁻) can also form weak hydrogen bonds with organic cations in the perovskite, physically preventing their migration and escape.

[0026] Synergistic stabilization of cations: Imidazole cations are anchored to the perovskite surface through electrostatic interactions, not only regulating crystallization and increasing grain size, but also forming a dynamic electrostatic barrier after polymerization, effectively inhibiting the migration of halide ions under UV excitation. The "ion pairs" formed by cations and anions enhance the overall stability of adsorption at the interface, achieving long-term passivation. This "lock-in effect" inhibits the UV-induced decomposition reaction chain at its source, which is key to improving the UV stability of the device.

[0027] Mechanism 2: Multilevel dynamic self-healing mechanism mediated by ion aggregates

[0028] The self-healing ability of this material does not rely on a single dynamic disulfide bond, but rather on a multi-level repair process initiated by ion aggregates and involving the synergistic action of multiple dynamic bonds:

[0029] Level 1: Ultra-fast startup (ion aggregate dissociation and recombination)

[0030] In polymer networks, dynamic ionic aggregates formed between imidazole cations and anions can reversibly dissociate and recombine under heat (60-100°C) or micro-stress. This endows polymer chain segments with extremely high mobility, driving the material to flow towards the crack within minutes, achieving initial physical closure of the crack.

[0031] Level 2: Robust recovery (dynamic covalent / coordinate bond exchange)

[0032] After the crack initially closes, the dynamic disulfide bonds (-SS-) in the network and the coordination bonds between the polyionic liquid and perovskite Pb²⁺ begin to undergo exchange reactions. These bonds have high energies and can effectively restore the mechanical strength of the cross-linked network and the electrical connectivity at the crack, ensuring complete recovery of performance after self-healing.

[0033] This multi-level mechanism combines "rapid initial repair" with "later strength recovery," which is the core of the material's efficient, tough, and self-healing capabilities.

[0034] The preparation method of this invention is briefly described as follows:

[0035] A 1-vinyl-3-alkylimidazolium ionic liquid monomer is mixed with a multi-thiol (or double-bond) crosslinking agent (such as PETMP) at a certain mass ratio (preferably 2:1 to 5:1), and a thermal initiator (such as AIBN) is added. The mixture is then reacted at 70-110°C for 10-30 minutes to obtain the target crosslinked polyionic liquid material. When using a multi-thiol crosslinking agent, to further enhance the self-healing properties, the above material can be compounded with thioctic acid containing dynamic disulfide bonds. As an additive for the perovskite layer, the above-mentioned crosslinked polyionic liquid material with self-healing function is incorporated into the perovskite precursor solution at a concentration typically of 0.1-5 mg / mL.

[0036] Beneficial effects

[0037] Compared with the prior art, the present invention has the following outstanding advantages:

[0038] 1. Excellent UV stability

[0039] The "ionic liquid locking effect" significantly suppressed UV-induced ion migration and material decomposition. This was achieved under a nitrogen atmosphere (UVA-365, 125.0 mW / cm²). 2 After continuous irradiation for 134 hours, the device efficiency retention rate can reach over 90%, far exceeding that of untreated devices.

[0040] 2. Highly efficient and robust self-healing ability

[0041] Based on the "multi-level dynamic self-healing mechanism", the microcracks in the perovskite thin film doped with this material can be completely repaired when heated at 60-100°C for 5-10 minutes. After 8000 bends, the efficiency of the flexible device drops to 84% of the initial value, and the efficiency recovery rate of the self-healed device exceeds 98%.

[0042] 3. Synergistically improve overall performance

[0043] While passivating defects and improving crystal quality, the material can also form a three-dimensional polymer network that serves as an internal encapsulation layer, significantly improving the hydrophobicity of the film (the water contact angle can be increased by more than 20°), thereby simultaneously improving the initial photoelectric conversion efficiency and long-term environmental stability of the device. After being stored in an inert atmosphere for 2000 hours, the efficiency retention rate is >90%.

[0044] 4. Good process compatibility

[0045] This material is soluble in common solvents used in perovskite precursors (such as DMF and DMSO) and can be introduced through a simple doping process without the need for complex additional preparation steps, making it suitable for large-scale production. Attached Figure Description

[0046] Figure 1 A schematic diagram of an inverted perovskite solar cell device;

[0047] Figure 2 The structural formula of the cross-linked polyionic liquid material;

[0048] Figure 3 The infrared spectrum of the PETMP-VEIMS material of this invention;

[0049] Figure 4 The JV curve test results are for the inverted perovskite solar cells in Examples 5, 10 and Comparative Example 1;

[0050] Figure 5 The graphs show the photoelectron conversion quantum efficiency and integral current of PerSCs in Examples 5, 10, and Comparative Example 1.

[0051] Figure 6 SEM images of the perovskite layers in Examples 5, 10, and Comparative Example 1;

[0052] Figure 7 Images of the self-healing materials in Examples 1 and 8;

[0053] Figure 8 Image of the self-healing perovskite layer in Example 12;

[0054] Figure 9 The images show the contact angles of the perovskite films in Examples 5, 10, and Comparative Example 1.

[0055] Figure 10 The images show the long-term stability of PerSCs in Examples 5, 10, and Comparative Example 1.

[0056] Figure 11 The JV curve test results are for the inverted perovskite solar cells in Examples 6, 7 and Comparative Example 1;

[0057] Figure 12 The JV curve test results are for the inverted perovskite solar cells in Examples 11, 12 and Comparative Example 1;

[0058] Figure 13 The JV curve test results are for the inverted perovskite solar cells in Examples 15, 16 and Comparative Example 1;

[0059] Figure 14 The JV curve test results are for the inverted perovskite solar cells in Examples 21, 22 and Comparative Example 1;

[0060] Figure 15 Image of the self-healing material film in Example 17;

[0061] Figure 16 Image of the self-healing perovskite film in Example 21;

[0062] Figure 17 Images showing the contact angles of the perovskite films in Example 21 and Comparative Example 1;

[0063] Figure 18 DSC charts of the materials from Example 1, polythiooctanoic acid, Example 8, and Example 17;

[0064] Figure 19 PCE recovery diagrams for Example 10 and Comparative Example 1;

[0065] Figure 20 The UV stability diagrams for Examples 5, 10, 21 and Comparative Example 1 under air atmosphere are shown.

[0066] Figure 21 The UV stability diagrams for Examples 5, 10, 21 and Comparative Example 1 under a nitrogen atmosphere are shown. Detailed Implementation

[0067] The present invention will now be described in detail with reference to the accompanying drawings.

[0068] Examples 1-4, 13, and 17-20 are examples of cross-linked polyionic liquid materials; Examples 8-9 and 14 are examples of self-healing and reinforcing compositions; Examples 5-7, 15, and 21-22 are examples of cross-linked polyionic liquid materials as perovskite layer additives; and Examples 10-12 and 16 are examples of self-healing and reinforcing compositions as perovskite layer additives.

[0069] Comparative Example 1

[0070] like Figure 1 This is a schematic diagram of an inverted perovskite solar cell. The fabrication steps for the inverted cell are as follows:

[0071] (1) ITO substrate treatment: The indium tin oxide (ITO) glass was ultrasonically cleaned in sequence with detergent, water, deionized water, acetone and isopropanol for 20 min, and then dried and treated with Plasma ozone for 10 min.

[0072] (2) Preparation of HTL: 0.5 mg MeO-2PACz was dissolved in 1 ml of anhydrous ethanol. The solution was spin-coated at 4000 rpm for 30 s and then annealed at 100 °C for 10 min under a nitrogen atmosphere.

[0073] (3) Preparation of perovskite layer: 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85 A PbI3 perovskite precursor solution was prepared, requiring an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0074] (4) Preparation of ETL: 0.1 vol% phenylnaphthalene was added to a chlorobenzene solution of 20 mg / ml PCBM and stirred, then spin-coated on PAL at 3000 rpm for 30 s. Then heated at 70 °C for 5 min.

[0075] (5) Preparation of the interface layer: Spin-coating a 0.5 mg / ml BCP isopropanol solution at 5000 rpm for 30 s, followed by heating at 70 ℃ for 5 min.

[0076] (6) Electrode preparation: at 7×10 -4 Ag electrodes were fabricated by vacuum evaporation deposition onto the top of the sample, with the deposition area defined by a mask at 4.00 mm. 2 The device area.

[0077] Device testing: The JV curve of the perovskite solar cell was tested under the San-Ei Electric CE solar simulator at a light intensity of 100 mW·cm. -2 The device performance was tested using a Keithley 2400 test setup. It was calibrated with a certified silicon solar cell prior to testing. Measurements were taken using both reverse scan (0.02 V → -1.2 V, 0.04 V step) and forward scan (-1.2 V → 0.02 V, 0.04 V step). Incident photon-electron conversion efficiency (IPCE) was determined using an IPCE system (Newport). The system was calibrated with a certified silicon solar cell prior to testing, and IPCE data was collected in DC mode.

[0078] Example 1

[0079] A 5:1 ratio of 1-vinyl-3-ethylimidazolium sulfate (VEIMS) to pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP) was used as a thermal initiator (AIBN). The thiol groups in PETMP underwent an alcohol-olefin crosslinking reaction. The reaction temperature was 110°C, and the reaction time was 10 minutes, yielding a viscous crosslinked polyionic liquid material, named PETMP-VEIMS. The structural formula of the crosslinked polyionic liquid material is shown below. Figure 2 As shown. Where a=2, R is ethyl, X — For EtSO4 — . Figure 3 This is the infrared spectrum of the PETMP-VEIMS material in this embodiment. As shown in the previous infrared spectral analysis of ionic liquid VEIMS, the wavelength at 1653 cm⁻¹... -1 This is the C=C stretching vibration of the vinyl group in the imidazole ring side chain, 961 cm⁻¹. -1 The out-of-plane bending vibration of -CH=CH2 in vinyl groups is observed at 1653 cm⁻¹. -1 and 961 cm -1 The characteristic peak almost disappeared, indicating that vinyl groups participated in the chemical reaction. The resulting PETMP-VEIMS ion-conductive elastomer contained almost no free vinyl groups, verifying the previous reaction equation that ionic liquid VEIMS can undergo self-addition polymerization. The raw material PETMP contained a peak at 2570 cm⁻¹. −1 There is a -SH vibration peak at 2570 cm⁻¹, while in PETMP-VEIMS, there is a peak at 2570 cm⁻¹. −1The disappearance of the -SH vibration peak indicates that the thiol group participated in the reaction, which verifies that the thiol group can undergo a thiol-ene click reaction with the vinyl group.

[0080] Example 2

[0081] With a VEIMS to PETMP ratio of 4:1 and 0.1 wt% thermal initiator AIBN, the thiol groups in pentaerythritol tetrakis(3-mercaptopropionic acid) (PETMP) undergo an alcohol-olefin crosslinking reaction. The reaction temperature is 110 °C and the reaction time is 10 minutes, yielding a viscous crosslinked polyionic material with self-healing properties.

[0082] Example 3

[0083] With a VEIMS to PETMP ratio of 5:1 and 0.1 wt% thermal initiator AIBN, the thiol groups in pentaerythritol tetrakis(3-mercaptopropionic acid) (PETMP) undergo an alcohol-olefin crosslinking reaction. The reaction temperature is 90 °C and the reaction time is 10 minutes, yielding a viscous crosslinked polyionic liquid.

[0084] Example 4

[0085] With a VEIMS to PETMP ratio of 5:1 and 0.1 wt% thermal initiator AIBN, the thiol groups in pentaerythritol tetrakis(3-mercaptopropionic acid) (PETMP) underwent an alcohol-olefin crosslinking reaction. The reaction temperature was 110 °C and the reaction time was 20 minutes, yielding a viscous crosslinked polyionic liquid.

[0086] Example 5

[0087] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. The PETMP-VEIMS prepared in Example 1 was added as an additive to the perovskite precursor solution.

[0088] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. For devices doped with PETMP-VEIMS, it was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a doping concentration of 0.6 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm and 5000 rpm / s for 10 s and 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0089] Example 6

[0090] The difference between this embodiment and Embodiment 5 lies in the different amount of PETMP-VEIMS doping in the perovskite layer.

[0091] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The PETMP-VEIMS prepared in Example 1 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a doping level of 0.3 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm / s for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100°C for 30 min.

[0092] Example 7

[0093] The difference between this embodiment and Embodiment 5 lies in the different amount of PETMP-VEIMS doping in the perovskite layer.

[0094] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The PETMP-VEIMS prepared in Example 1 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a doping level of 0.9 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm / s for 35 s, respectively. After the last 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100°C for 30 min.

[0095] Example 8

[0096] The cross-linked polyionic liquid material obtained in Example 1 was mixed with thioctic acid at a mass ratio of 6:5 and stirred until homogeneous to obtain a self-healing and reinforcing composition, which was named PTA-PETMP-VEIMS.

[0097] Example 9

[0098] The difference between this embodiment and Example 8 lies in the preparation of the self-healing and enhancing composition. The synthesis method steps are as follows:

[0099] The cross-linked polyionic liquid material obtained in Example 1 was mixed with thioctic acid at a mass ratio of 1:1 and stirred until homogeneous to obtain a self-healing and reinforcing composition.

[0100] Example 10

[0101] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. The PTA-PETMP-VEIMS prepared in Example 8 was added as an additive to the perovskite precursor solution.

[0102] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The PTA-PETMP-VEIMS prepared in Example 8 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 1.2 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm and 5000 rpm / s for 10 s and 35 s, respectively. After the last 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0103] Example 11

[0104] The difference between this embodiment and Embodiment 10 is that the amount of PTA-PETMP-VEIMS incorporated is different.

[0105] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The PTA-PETMP-VEIMS prepared in Example 8 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 0.8 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm and 5000 rpm / s for 10 s and 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0106] Example 12

[0107] The difference between this embodiment and Embodiment 10 is that the amount of PTA-PETMP-VEIMS incorporated is different.

[0108] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The PTA-PETMP-VEIMS prepared in Example 8 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 1.6 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm and 5000 rpm / s for 10 s and 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0109] Example 13

[0110] 0.1 mol of 1-vinylimidazolium was placed in a metal bath and heated. 0.11 mol of bromoethane was added dropwise to a single-necked flask using a constant-pressure funnel. The mixture was kept dry during the reaction. After the reaction was complete, the product was transferred to a separatory funnel, washed repeatedly, and separated. The lower layer of crude ionic liquid was collected, and excess solvent was removed by rotary evaporation under reduced pressure to finally obtain 1-vinyl-3-ethylimidazolium bromide ionic liquid. The ratio of 1-vinyl-3-ethylimidazolium bromide ionic liquid to PETMP was 5:1. Under the influence of 0.1 wt% thermal initiator AIBN, the thiol groups in pentaerythritol tetrakis(3-mercaptopropionic acid) (PETMP) underwent an alcohol-olefin crosslinking reaction. The reaction temperature was 110 °C, and the reaction time was 10 minutes, yielding a viscous crosslinked polyionic liquid, which was named PETMP-IL-2. Where a=2, R is ethyl, and X... — For Br — .

[0111] Example 14

[0112] The cross-linked polyionic liquid PETMP-IL-2 obtained in Example 13 was mixed with thioctic acid at a mass ratio of 6:5 and stirred until homogeneous to obtain a self-healing and reinforcing composition, which was named PTA-PETMP-IL-2.

[0113] Example 15

[0114] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. PETMP-IL-2 prepared in Example 13 was added as an additive to the perovskite precursor solution.

[0115] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. PETMP-IL-2 prepared in Example 13 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 0.6 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0116] Example 16

[0117] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. The self-healing and reinforcing composition prepared in Example 14 was added as an additive to the perovskite precursor solution.

[0118] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. PTA-PETMP-IL-2 prepared in Example 14 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 1.2 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0119] Example 17

[0120] The difference between this embodiment and Example 2 lies in the preparation of the cross-linked polyionic liquid material. The synthesis method steps are as follows:

[0121] VEIMS and N,N'-bis(acryloyl)cysteine ​​were dissolved in trifluoroethanol at a mass ratio of 2.4:1 and reacted with 0.1 wt% AIBN as a thermal initiator. The reaction temperature was 75°C and the reaction time was 20 min. This mixture was named BAC-VEIMS. Where a=2, R is ethyl, and X... — For EtSO4 — .

[0122] Example 18

[0123] The difference between this embodiment and Example 17 lies in the preparation of the cross-linked polyionic liquid material. The synthesis method steps are as follows:

[0124] VEIMS and N,N'-bis(acryloyl)cysteine ​​were dissolved in trifluoroethanol at a mass ratio of 3:1 and reacted with 0.1 wt% AIBN as a thermal initiator. The reaction temperature was 75°C and the reaction time was 20 min.

[0125] Example 19

[0126] The difference between this embodiment and Example 2 lies in the preparation of the cross-linked polyionic liquid material. The synthesis method steps are as follows:

[0127] VEIMS and N,N'-bis(acryloyl)cysteine ​​were mixed and dissolved in trifluoroethanol at a mass ratio of 2.4:1, and the reaction was carried out in the presence of 0.1 wt% thermal initiator AIBN. The reaction temperature was 85°C, and the reaction time was 20 min.

[0128] Example 20

[0129] The difference between this embodiment and Example 2 lies in the preparation of the cross-linked polyionic liquid material. The synthesis method steps are as follows:

[0130] VEIMS and N,N'-bis(acryloyl)cysteine ​​were dissolved in trifluoroethanol at a mass ratio of 2.4:1 and reacted with 0.1 wt% AIBN as a thermal initiator. The reaction temperature was 75°C and the reaction time was 30 min.

[0131] Example 21

[0132] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. The cross-linked polyionic liquid material BAC-VEIMS prepared in Example 17 was added as an additive to the perovskite precursor solution.

[0133] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. BAC-VEIMS prepared in Example 17 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 0.75 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0134] Example 22

[0135] The difference between this embodiment and Comparative Example 1 lies in the preparation of the perovskite layer. The cross-linked polyionic liquid material BAC-VEIMS prepared in Example 17 was added as an additive to the perovskite precursor solution.

[0136] Preparation of the perovskite layer: A 1.63 M perovskite layer with the chemical formula CsI was prepared by dissolving CsI, FAI, MAI, and PbI2 in a DMF / DMSO mixed solvent (v / v = 4 / 1). 0.05 MA 0.10 FA 0.85 The PbI3 perovskite precursor solution required an excess of 5 mol% PbI2 to improve device performance. Then, 15 mol% MACl was added to the perovskite precursor solution and stirred. The BAC-VEIMS prepared in Example 17 was dissolved in a DMF / DMSO mixed solvent (v / v = 4 / 1) and incorporated into the perovskite precursor solution at a concentration of 1.5 mg / ml. The perovskite precursor solution was dropped onto an ITO / MeO-2PACz substrate and spin-coated at 1000 rpm for 10 s and 5000 rpm / s for 35 s, respectively. After the countdown was 10 s, 300 μL of anisole was dropped onto the sample. The sample was then heated at 100 °C for 30 min.

[0137] Figure 4 The figures show the JV curve test results of the inverted perovskite solar cells in Examples 5, 10, and Comparative Example 1. As can be seen from the figures, after adding 0.6 mg / ml PETMP-VEIMS and 1.2 mg / ml PTA-PETMP-VEIMS, the VJ of the PSCs increased. OC Significantly increased, from 1.10 V to 1.103 V and 1.119 V respectively. Jsc increased from 25.18 mA cm⁻¹ of the control device.-2 Increased to 25.55 mA cm -2 and 26.17mA cm -2 The FF also increased from 79.01% in the control device to 82.06% and 82.65%. Improvements in various device parameters led to an increase in the device's PCE from 21.88% to 23.12% and 24.2%. Device V OC The increase in Jsc and FF indicates that the addition of this material improves the energy level matching between the functional layers of the perovskite solar cell. It may also be that the introduction of PETMP-VEIMS and PTA-PETMP-VEIMS passivates defects and reduces non-radiative recombination losses. The increase in Jsc and FF may be due to the fact that the introduction of PETMP-VEIMS and PTA-PETMP-VEIMS can regulate film formation, enhance perovskite crystallinity, thereby improving charge transport performance and enhancing the photoelectric performance of PSCs. The presence of carbonyl (C=O) and sulfonic acid (S=O) groups in PETMP-VEIMS can interact with Pb... + Coordination and passivation of perovskite defects regulate crystallization. The introduction of PTA-PETMP-VEIMS enables the perovskite layer to self-heal. The cross-linked network structure of both also serves as an internal encapsulation mechanism.

[0138] Figure 5 The graphs show the photoelectron conversion quantum efficiency and integrated current of PerSCs in Examples 5, 10, and Comparative Example 1. Compared to the blank device, the PTA-PETMP-VEIMS-based devices exhibit stronger photoelectric response. The short-circuit current curve is obtained by integrating the EQE curve, and the integrated short-circuit current value is basically consistent with the short-circuit current value obtained from the actual test current-voltage curve above. The integrated current of the blank device is 24.17 mA cm⁻¹. -2 The integrated currents of the devices modified with PETMP-VEIMS and PTA-PETMP-VEIMS were 24.74 mA cm⁻¹, respectively. -2 and 25.55 mAcm -2 This demonstrates that doping perovskites with PETMP-VEIMS and PTA-PETMP-VEIMS can improve the extraction and transport of photogenerated electrons, increase the short-circuit current of the device, and effectively promote the transfer and transport of interlayer charges.

[0139] Figure 6SEM images of the perovskite layers in Examples 5, 10, and Comparative Example 1 are shown. The morphological changes of the films before and after introducing PETMP-VEIMS and PTA-PETMP-VEIMS into the perovskite precursor solution were observed using SEM. All three perovskite films were dense and pinhole-free, but the samples with added PETMP-VEIMS and PTA-PETMP-VEIMS showed increased grain size, while the control sample had smaller grain size and a higher number of grain boundaries. Grain boundaries, as high-dimensional defects, not only lead to significant nonradiative recombination energy loss within the device but also act as channels for water-oxygen erosion and accelerate the degradation of PSC performance. This indicates that PETMP-VEIMS and PTA-PETMP-VEIMS, with their multifunctional groups, effectively modulate the crystallization process. It is worth noting that by statistically analyzing the grain size of different films, a corresponding perovskite grain size distribution chart was obtained. It was found that the grain size of most of the control films was 500 nm, while the grain size of the target perovskite films of PETMP-VEIMS and PTA-PETMP-VEIMS was slightly larger than that of the blank, both around 700 nm.

[0140] Figure 7 Images show the self-healing properties of the materials in Examples 1 and 8. Scratches on the PETMP-VEIMS membrane self-healed within 2 hours at room temperature. Scratches on the PTA-PETMP-VEIMS membrane self-healed within 20 minutes at room temperature.

[0141] Figure 8 This is an image of the self-healing perovskite layer in Example 10. The perovskite film doped with PTA-PETMP-VEIMS healed its scratches after heating at 100°C for 10 minutes, successfully realizing a self-healing perovskite. This is because the PTA-PETMP-VEIMS elastomer contains abundant dynamic bonds, such as disulfide bonds, ionic bonds, and hydrogen bonds.

[0142] Figure 9 Images show the contact angles of the perovskite thin films in Examples 5, 10, and Comparative Example 1. Hydrophilicity / hydrophobicity were tested using contact angle measurements on pure PVK films, PVK films doped with PETMP-VEIMS, and PVK films doped with PTA-PETMP-VEIMS. The water contact angle of the pure PVK film was 50°, while the water contact angles of the PVK films doped with PETMP-VEIMS and PTA-PETMP-VEIMS were 60° and 72.5°, respectively, significantly larger than those of the pure PVK film. This indicates that the perovskite solar devices prepared with PETMP-VEIMS and PTA-PETMP-VEIMS materials exhibit higher water stability.

[0143] Figure 10The images show the long-term stability of PerSCs in Examples 5, 10, and Comparative Example 1. Normalized efficiency plots were recorded for the unpackaged standard device, PETMP-VEIMS device, and PTA-PETMP-VEIMS device stored at an ambient temperature of 25°C in an N2 atmosphere. After 2000 hours of storage, the PCE of the standard perovskite solar cell had significantly decreased to 73.75% of its initial value, while the decrease in PCE for the PETMP-VEIMS and PTA-PETMP-VEIMS perovskite solar cells was significantly reduced. After 2000 hours, the PETMP-VEIMS and PTA-PETMP-VEIMS cells still maintained approximately 89.67% and 92.99% of their initial efficiencies, respectively. Crosslinking compounds such as PETMP-VEIMS and PTA-PETMP-VEIMS can effectively increase the environmental stability of perovskite films and improve the repeatability and long-term stability of PSCs. This is mainly because the polymers can not only improve the crystal quality of perovskite and passivate internal defects of perovskite, but also the three-dimensional polymer network they form can coat the perovskite grains, effectively improving the hydrophobicity of the perovskite film, thereby reducing the degradation of the perovskite film caused by water intrusion and improving the long-term stability of the device.

[0144] Figure 11 The JV curve test results are for the inverted perovskite solar cells in Examples 6, 7, and Comparative Example 1. After adding 0.3 mg / ml PETMP-VEIMS, the FF increased from 79.01% in the control device to 82.38%, resulting in an increase in the PCE from 21.88% to 22.71%. After adding 0.9 mg / ml PETMP-VEIMS, the FF also increased from 79.01% in the control device to 83.13%, resulting in an increase in the PCE from 21.88% to 22.16%.

[0145] Figure 12 The JV curve test results are for the inverted perovskite solar cells in Examples 11, 12, and Comparative Example 1. After adding 0.8 mg / ml of PTA-PETMP-VEIMS, the Vt of the PSCs... OC Almost unchanged. Jsc from 25.18 mAcm of the control device. -2 Increased to 25.24 mA cm -2 The FF also increased from 79.01% in the control device to 83.32%. Improvements in various device parameters led to an increase in the device's PCE from 21.88% to 23.13%. After adding 1.6 mg / ml of PTA-PETMP-VEIMS, the V of PSCs... OC Almost unchanged. Jsc from 25.18 mA cm⁻¹ of the control device.-2 Increased to 25.27 mA cm -2 The FF also increased from 79.01% in the control device to 82.19%. The improvement in various parameters of the device increased the PCE from 21.88% to 22.84%.

[0146] Figure 13 The JV curve test results are for the inverted perovskite solar cells in Examples 15, 16, and Comparative Example 1. After adding 0.6 mg / ml of PETMP-IL-2, the Vt of the PSCs... OC From 1.100V to 1.107V of the reference device, Jsc increased from 25.18 mA cm⁻¹ of the reference device. -2 Increased to 25.81 mA cm -2 The FF remained almost unchanged. Improvements in various device parameters increased the device's PCE from 21.88% to 22.52%. After adding 1.6 mg / ml of PTA-PETMP-IL-2, the V of the PSCs... OC The voltage was increased from 1.100V to 1.113V compared to the reference device. Jsc increased from 25.18 mA cm⁻¹ compared to the reference device. -2 Increased to 26.22 mA cm -2 The FF also increased from 79.01% in the control device to 80.48%. The improvement in various parameters of the device increased the PCE from 21.88% to 23.48%.

[0147] Figure 14 The JV curve test results are for the inverted perovskite solar cells in Examples 21, 22, and Comparative Example 1. After adding 0.75 mg / ml of BAC-VEIMS, the Vt of the PSCs... OC The voltage was increased from 1.100V to 1.118V compared to the reference device. Jsc increased from 25.18 mA cm⁻¹ compared to the reference device. -2 Increased to 26.22 mA cm -2 The FF also increased from 79.01% in the control device to 83.61%. Improvements in various device parameters led to an increase in the PCE from 21.88% to 24.52%. After adding 1.5 mg / ml of BAC-VEIMS, the Jsc of PSCs increased from 25.18 mA cm⁻¹ in the control device. -2 Increased to 25.97 mA cm -2 The FF also increased from 79.01% in the control device to 79.98%. The improvement in various parameters of the device increased the PCE from 21.88% to 22.84%.

[0148] Figure 15 This is an image of the self-healing BAC-VEIMS material in Example 17. The BAC-VEIMS film healed after being heated at 60°C for 5 minutes.

[0149] Figure 16 This is an image of the self-healing perovskite layer in Example 21. The BAC-VEIMS-doped perovskite film healed scratches after heating at 60°C for 5 minutes, successfully realizing a self-healing perovskite.

[0150] Figure 17 Images showing the contact angles of the perovskite thin films in Example 21 and Comparative Example 1. Hydrophilicity / hydrophobicity were tested using contact angle measurements on pure PVK films and PVK films doped with BAC-VEIMS. The water contact angle of the pure PVK film was 55.25°, while the water contact angle of the PVK film doped with BAC-VEIMS was 61.93°, which is greater than that of the pure PVK film. This indicates that the perovskite solar cell device prepared with BAC-VEIMS material has higher water stability.

[0151] Figure 18 The images show the DSC plots of the materials from Examples 1, 8, and 17. Differential scanning calorimetry (DSC) was used to measure the glass transition temperature (Tg) of the materials. It can be seen that the Tg onset point of PETMP-VEIMS is -35.11℃, and the midpoint is -25.73℃; the Tg onset point of PTA is -47.40℃, and the midpoint is -37.16℃; and the Tg onset point of PTA-PETMP-VEIMS is -40.55℃, and the midpoint is -49.53℃. Therefore, the Tg of PTA-PETMP-VEIMS is relatively low, indicating a lower healing temperature. The Tg onset point of BAC-VEIMS is -81.22℃, and the midpoint is -77.13℃, indicating that the healing conditions of this material are even lower.

[0152] Figure 19 The images show the PCE recovery diagrams for Example 10 and Comparative Example 1. After 4000 bending cycles, the efficiency of the flexible device decreased. Heating it at 100 degrees Celsius for 10 minutes resulted in some recovery of the device efficiency. After another 4000 bending cycles, the efficiency of the flexible device decreased to 84% of its initial value. The self-healing device showed an efficiency recovery rate exceeding 98%.

[0153] Figure 20 The UV stability graphs for Examples 5, 10, 21, and Comparative Example 1 are shown. Simulated solar ultraviolet light (UVA-365, 168.8 mW / cm²) in an air atmosphere were recorded. 2Stability under continuous irradiation. After 9 hours of storage, the PCE of the standard perovskite solar cell had decreased significantly to 69.06% of the initial value, while the efficiency decline of the PETMP-VEIMS, PTA-PETMP-VEIMS, and BAC-VEIMS devices was significantly reduced, and they were still able to maintain an initial efficiency of nearly 90.09%, 91.79%, and 91.00%, respectively.

[0154] Figure 21 The UV stability graphs for Examples 5, 10, 21, and Comparative Example 1 are shown. Simulated solar ultraviolet light (UVA-365, 125.0 mW / cm²) under a nitrogen atmosphere were recorded. 2 Stability under continuous irradiation. After 134 hours of storage, the PCE of the standard perovskite solar cell had decreased significantly to 74.72% of the initial value, while the efficiency decline of the PETMP-VEIMS, PTA-PETMP-VEIMS, and BAC-VEIMS devices was significantly reduced, and they were still able to maintain an initial efficiency of nearly 88.72%, 90.80%, and 91.76%, respectively.

Claims

1. A cross-linked polyionic liquid additive material for improving the ultraviolet stability and self-healing ability of perovskite solar cells, characterized in that, The additive is a dynamic cross-linked network polymer, and its general structural formula is shown in (Ⅰ): General Formula (I) In the formula: PIL = It is a polyionic liquid segment derived from a 1-vinyl-3-alkylimidazolium salt monomer, wherein the alkyl group R = - C a H (2a+1) In the formula, a is an integer from 1 to 18; X — Selected from F — Cl — ,Br — I — BF 4— PF 6— SCN — , Tf2N⁻, BPh4⁻, HSO4⁻, EtSO4 — TFSI — H2PO4 — CF3COO⁻, CH3COO⁻, OH — [Core] is an anion of amino acid anions; [Core] is a crosslinking agent in in-situ crosslinked polymers, containing thiol groups and double bonds.

2. The cross-linked polyionic liquid additive material according to claim 1, characterized in that, [Core] is the crosslinking agent in in-situ crosslinked polymers. It is divided into two types: crosslinking agents containing three or more thiol functional groups and crosslinking agents containing two or more carbon-carbon double bonds. Crosslinking agents containing three or more thiol functional groups are pentaerythritol tetrakis(3-mercaptopropionic acid) ester, trimethylolpropane tris(3-mercaptopropionic acid) ester, or polyethylene glycol dithiol. Crosslinking agents containing two or more carbon-carbon double bonds are N,N'-bis(acryloyl)cysteine. The number of thiol groups and double bonds in [Core] determines the degree of crosslinking.

3. The method for preparing the cross-linked polyionic liquid additive material as described in claim 1, characterized in that, The steps are as follows: Mix the imidazole ionic liquid with vinyl groups with the crosslinking agent with thiol or vinyl groups, add the initiator, stir evenly, react under heating conditions, cool at room temperature, and obtain a viscous crosslinked polyionic liquid additive material.

4. The preparation method according to claim 3, characterized in that, The ionic liquid is ethyl 1-vinyl-3-ethylimidazolium sulfate, and the initiator is AIBN.

5. The preparation method according to claim 3, characterized in that, The crosslinking agent with thiol groups is pentaerythritol tetrakis(3-mercaptopropionic acid) ester. The mass ratio of the ionic liquid to pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 4~5:

1. The reaction temperature of the ionic liquid and pentaerythritol tetrakis(3-mercaptopropionic acid) ester is 90°C~110°C, and the reaction time is 10 min~20 min.

6. The preparation method according to claim 3, characterized in that, The crosslinking agent with thiol or vinyl groups is N,N'-bis(acryloyl)cysteamine, the mass ratio of ionic liquid to N,N'-bis(acryloyl)cysteamine is 2.4~3:1, the reaction temperature of ionic liquid and N,N'-bis(acryloyl)cysteamine is 75°C~85°C, and the reaction time is 20 min~30 min.

7. A self-healing and reinforcing composition comprising dynamic disulfide bonds, characterized in that, It comprises: the cross-linked polyionic liquid additive material of claim 1 and thioctic acid; wherein the mass ratio of the cross-linked polyionic liquid additive material to thioctic acid is (6:5) to (1:1).

8. A perovskite solar cell, comprising a substrate, an electrode layer, a hole transport layer, a perovskite active layer, an electron transport layer, and another electrode layer stacked sequentially, characterized in that, The perovskite active layer contains an effective amount of the cross-linked polyionic liquid additive material as described in claim 1 or the self-healing reinforcing composition as described in claim 6.

9. The perovskite solar cell according to claim 8, characterized in that, The doping concentration of the cross-linked polyionic liquid additive or self-healing reinforcing composition in the perovskite precursor solution is 0.1-5.0 mg / mL.

10. A method for improving the ultraviolet stability and mechanical durability of perovskite solar cells, characterized in that, The cross-linked polyionic liquid additive material of claim 1 or the self-healing and reinforcing composition of claim 7 is doped into the perovskite precursor solution at a concentration of 0.1-5.0 mg / mL and used to prepare the active layer of a perovskite solar cell.

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