Method for improving thermal stability of perovskite material through chemical competitive coordination

Abstract

The invention relates to a method for improving the thermal stability of a perovskite material through chemical competitive coordination, and belongs to the technical field of photoelectric materials and device stability. According to the invention, a two-site additive eperisone hydrochloride (EH) is introduced into a lead iodide precursor solution, and competitive coordination with a residual solvent DMSO is realized in the preparation process of the perovskite device, so that volatilization of DMSO is effectively promoted, and multiple degradation pathways caused by DMSO are inhibited. The residual DMSO is easy to cause the formation of a nano gap at a crystal boundary, so that ion migration and non-radiative recombination are intensified; the moisture absorption characteristic can also initiate moisture infiltration, so that Pb-I bonds are promoted to be hydrolyzed and converted into a non-photoactive delta phase; meanwhile, lattice stress generated by local degradation can further cause irreversible PbI2 segregation. According to the passivation strategy, DMSO removal and vacancy passivation are remarkably promoted, meanwhile, the interface moisture resistance is enhanced, and the stability of the perovskite phase is cooperatively improved.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of the thermal stability of solar cells, and particularly relates to a method for improving the thermal stability of perovskite materials by chemical competitive coordination. BACKGROUND

[0002] Perovskite solar cells (PSCs) have achieved certified power conversion efficiencies (PCEs) of over 26%, becoming a competitive candidate to the mature photovoltaic technologies. Their low-temperature solution processing performance brings significant advantages for manufacturing, however, the operational instability under thermal and humid conditions remains a fundamental barrier for commercialization. One key but less investigated failure mechanism lies in the persistent presence of coordinated solvents (especially dimethyl sulfoxide, DMSO) in the crystalline intermediates formed during perovskite nucleation.

[0003] DMSO is indispensable for directing the formation of photoactive alpha-phase perovskite by forming stable adducts such as PbI2·DMSO. However, its high boiling point (189℃) and strong Lewis basicity cause kinetic barriers for complete removal during annealing. Residual DMSO triggers a chain degradation pathway: (1) thermal evaporation generates nanoscale voids at grain boundaries, accelerating ion migration and non-radiative recombination; (2) hygroscopicity promotes water penetration, triggering Pb-I bond hydrolysis and phase transformation to the non-photoactive delta-phase δ-FAPbI3; (3) lattice strain caused by local decomposition leads to irreversible PbI2segregation. In-situ studies show that DMSO-PbI2intermediates rapidly hydrate at about 60% relative humidity, inhibiting the complete formation of alpha-FAPbI3, while producing delta-phase impurities that destroy the crystalline order.

[0004] To address the negative effects of residual DMSO, researchers have proposed various solutions. In terms of solvent engineering, the introduction of low-boiling co-solvents (such as diethyl ether) forms azeotropes with DMSO, which can significantly reduce the de-embedding energy barrier and promote the co-evaporation of residual solvents. In terms of additive regulation, functional molecules (such as ethyl acrylate, L-arginine hydrochloride) can form passivation layers through polymerization, not only passivating defects, but also blocking water and oxygen. Although solvent engineering and polymerizable additives partially solve individual degradation modes, they fail to achieve complete removal of DMSO, and also cannot balance defect inhibition and phase stability. SUMMARY

[0005] The present application adopts a double-site passivation strategy to introduce EH into perovskite precursors to prepare high-efficiency and stable PSCs. The results show that the carbonyl group of EH can coordinate with Pb 2+Strong coordination competitive substitution of DMSO promotes its removal and reduces vacancy defects; tertiary amine nitrogen guides ordered crystal growth through hydrogen bonding, and the hydrophobic piperidine ring migrates to the surface to form a molecular-level waterproof barrier; dissociated Cl⁻ fills iodine vacancies, inhibiting ion migration and passivating the interface. This strategy synergistically achieves efficient removal of DMSO residue, defect suppression, and interface stability, and retains 90% of the initial efficiency after 1000 hours of thermal aging at 85°C, providing a comprehensive and effective solution to overcome solvent-induced instability in perovskite solar cells.

[0006] This invention proposes a method to improve the thermal stability of perovskite materials through chemical competitive coordination. This method not only provides a practical technical path to overcome the efficiency bottleneck of PSCs, but also significantly enhances the stability of the device under high temperature conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for improving the thermal stability of perovskite materials through chemical competitive coordination, wherein EH solvent is added to the interior of the perovskite thin film.

[0008] Calculations of the electrostatic potential of EH show that the negatively charged carbonyl group in EH can react with the Pb group in PbI2. 2+ They interact to form Pb–O coordination bonds, which in turn cause DMSO to dissociate from the solvent coordination environment, thus achieving competitive coordination between ligands.

[0009] Next, the PbI2 thin film was observed using grazing incidence wide-angle X-ray scattering (GIWAXS). The results showed that the intensity of the DMSO-PbI2 diffraction ring was significantly reduced, indicating that EH played a significant role in the system and successfully displaced PbI2 from the DMSO-PbI2 complex.

[0010] To further investigate the interaction between FAI and EH, nuclear magnetic resonance (NMR) technology was used for characterization. The results showed that FAI approached EH significantly through hydrogen bonds, effectively promoting the formation of the perovskite structure.

[0011] Subsequently, the nucleation process of perovskite was observed using scanning electron microscopy (SEM), confirming that perovskite films can spontaneously form high-quality crystalline structures.

[0012] Subsequently, the output power of the perovskite device was characterized by current-voltage characteristic (JV) testing, and the results showed that the additive can effectively improve the photoelectric conversion efficiency of the perovskite device.

[0013] Finally, the change in PCE under different aging times was analyzed by normalized efficiency analysis, which verified the significant improvement in the thermal stability of the device.

[0014] A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following schemes: I. Cleaning and pretreatment of solar cell substrate: firstly, the glass substrate is sequentially cleaned in detergent, deionized water, acetone and ethanol by ultrasonic cleaning, then the cleaned glass substrate is dried, and finally the dried substrate is treated by ultraviolet plasma cleaning instrument to obtain sample ①; II. Preparation of electron transport layer: sample ① is fixed on the coating machine, SnO2 is deposited on the surface of sample ① by spin coating method to form the electron transport layer of solar cell, and then sample ② is obtained after annealing treatment; III. Preparation method of lead iodide solution: in an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl are accurately weighed and mixed according to the stoichiometric ratio, then dissolved in DMF and DMSO mixed solvent to form precursor solution, and stored after filtration treatment; IV. Preparation of additive solution: in an argon atmosphere glove box, EH is dissolved in DMF and stirred thoroughly, and then EH solution is obtained after filtration; V. Preparation of lead iodide solution containing additive: in the argon-filled glove box, different concentrations of EH solution are introduced into the PbI2 precursor solution, and the complete dissolution is promoted by stirring, then filtration treatment is carried out, and finally the PbI2 solution containing EH is obtained; VI. Preparation of organic salt solution: in an argon atmosphere glove box, 77 mg, 14 mg and 18 mg of formamidinium iodide (FAI), methylammonium iodide (MAI) and methylammonium chloride (MACl) are respectively weighed with a molar ratio of 5:1:3, dissolved in isopropanol (IPA) solvent, heated and stirred at 70°C for 3 hours to obtain a uniform organic salt precursor solution, and used; VII. Preparation of perovskite thin film: firstly, sample ② is transferred to the argon-filled glove box under vacuum condition, and the organic-inorganic hybrid perovskite thin film is prepared on the coating machine by spin coating method. The lead iodide solution containing additive in step V is added to the surface of sample ②, and then annealing is carried out after spin coating treatment to obtain sample ③. Then, sample ③ is placed on the coating machine again, and the organic salt solution is added quickly, then it is removed from the glove box for annealing treatment, and finally sample ④ is obtained; VIII. Preparation process of hole transport layer: the Spiro-OMeTAD solution is spin-coated on the surface of sample ④ to form sample ⑤; IX. Electrode preparation: silver (Ag) electrode is deposited on sample ⑤ by vacuum evaporation method, and the evaporation process is completed in the rotary evaporator to obtain a complete perovskite solar cell device.

[0015] In step one, the glass substrate used is ITO conductive glass sheet, which is cleaned by ultrasonic for 15 minutes, then dried in an oven at 80°C for 6 hours, and finally treated by UV plasma cleaning machine with a power of 60 W for 60 seconds.

[0016] In step two, the electron transport layer SnO2 is prepared by spin coating process at a rotation speed of 3000 rpm / min for 30 seconds on a film applicator in a fume hood with a relative humidity of 20% RH, and then annealed at 150°C for 30 minutes.

[0017] In step three, the lead iodide material is dissolved in a mixed solvent system composed of DMF and DMSO in a volume ratio of 960:40, the heating temperature during the reaction is set to 70-80°C, magnetic stirring is used for 10-12 hours, and a 0.45 μm organic phase filter head is used for solution filtration.

[0018] In step four, the mass fraction of EH solution is 10wt%, and magnetic stirring is used for 3-5 hours.

[0019] In step five, the mass fraction of EH solution is controlled between 0.1% and 0.5%.

[0020] In step six, the organic salt is dissolved in 1 mL IPA solution, the heating temperature is set to 70-80°C, and magnetic stirring is used for 1-3 hours.

[0021] In step seven, first, 50 μL of lead iodide solution containing additives is treated by static spin coating, the spin coating process parameters are set as follows: rotation speed 2000 rpm / min, duration 20 seconds; then annealed at 70°C for 1 minute. Next, 50 μL of organic salt solution is treated by dynamic spin coating, the rotation speed is kept at 2000 rpm / min during the spin coating process, and the solution is added at the 10th second; then annealed at 150°C for 30 minutes.

[0022] In step eight, the composition of Spiro-OMeTAD solution is 72.3 mg Spiro-OMeTAD, 17.5 μL Li-TFSI acetonitrile solution with a concentration of 520 mg mL⁻¹, and 28.8 μL t-BP (molar ratio of the three: 1:0.54:3.4, dissolved in 1 mL chlorobenzene), which is formed into a film by spin coating method, and the spin coating rotation speed is set to 4000 rpm for 30 seconds.

[0023] In step nine, the vacuum degree used for spin evaporation is not less than 1×10 -4 Pa, and the film deposition thickness is controlled to 80-100 nm.

[0024] The present invention has the following advantages: Through a clever EH multifunctional design, it achieves significant synergistic effects: carbonyl substitution of DMSO promotes the amine orientation of FA⁺, fills chloride ion vacancies, and encapsulates hydrophobic crystal boundaries. These combined effects not only significantly suppress defect formation, greatly reducing trap density, but also impart exceptional resistance to thermal degradation. As a result, the device achieves a power conversion efficiency of 26.06% and impressive stability: retaining over 90% of its initial efficiency after 1200 hours at 85 °C (ISOS - L⁻³). The strategic use of dual passivators as crystallization regulators reveals the enormous potential for molecular reuse to overcome the long-standing trade-off between efficiency and stability in solution-processed semiconductor materials. Specifically: To fundamentally solve the degradation problem caused by solvent residue. By introducing the EH molecule, its carbonyl group (C=O) reacts with Pb. 2+ Its coordination ability is significantly superior to that of DMSO, enabling it to efficiently and competitively replace DMSO molecules in the PbI2–DMSO intermediate, significantly reducing the insertion / extraction energy barrier and achieving complete removal of residual DMSO. This mechanism effectively blocks multiple degradation pathways caused by DMSO, including grain boundary nanopores caused by thermal evaporation, Pb-I bond hydrolysis induced by water infiltration, and the formation of δ-phase impurities, thereby significantly improving the intrinsic stability of the device.

[0025] Multifunctional collaborative passivation and protection mechanism EH possesses a unique four-fold synergistic effect: strong carbonyl coordination promotes DMSO removal and lead-related vacancy passivation; tertiary amine nitrogen guides the orderly arrangement of formamidinium iodide (FAI) through hydrogen bonding, improving crystal quality and inhibiting non-radiative recombination; the hydrophobic piperidine ring migrates to the surface after film formation, forming a dense molecular-level moisture barrier that effectively blocks environmental water and oxygen corrosion; and dissociated Cl⁻ ions precisely fill iodine vacancies (V⁻). I This significantly inhibits ion migration and improves interfacial charge transport efficiency.

[0026] It has strong process compatibility and potential for large-scale application. EH additives can be directly introduced into existing perovskite precursor solutions without complex process changes or additional equipment investment, and are compatible with large-area fabrication technologies such as large-scale coating and slot coating. This strategy uses readily available raw materials and is easy to operate, and is applicable not only to rigid substrates but also to flexible devices, showing significant potential for industrial application.

[0027] This provides a new approach to the stability study of perovskite solar cells. The double-site passivation mechanism disclosed in the research provides a new research direction for subsequent multifunctional molecular design, interface stabilization and defect coordination management, and has important scientific and practical significance for promoting the transition of perovskite solar cells from the laboratory to commercialization. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0029] Figure 1 Flow chart of a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 2 EH electrostatic potential in a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 3 GIWAXS of PbI2 thin films prepared in Comparative Example 1 and Example 1 in a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 4 NMR and mechanism diagram of FAI and PbI2-EH solution prepared in Comparative Example 2 and Example 2 in a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 5 In-situ SEM of the crystallization process of perovskite in Comparative Example 3 and Example 3 in a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 6 Efficiency comparison chart of devices of perovskite prepared in Comparative Example 4, Example 4, Example 5 and Example 6 in a method for improving the thermal stability of perovskite material by chemical competitive coordination; Figure 7 Influence of battery stability prepared in Comparative Example 4 and Example 5 in a method for improving the thermal stability of perovskite material by chemical competitive coordination. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] Example 1 A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following steps: I. Cleaning and pretreatment of solar cell substrate: The glass substrate is numbered using the initials of the person's name and loaded into the cleaning rack in order. Then, the glass substrate is ultrasonically cleaned with detergent, deionized water, acetone and ethanol in turn. After cleaning, the substrate is dried in an oven and then treated by a UV plasma cleaner to obtain sample ①; II. Sample ① is fixed on a spin coater, SnO2 is deposited on the surface of sample ① to form an electron transport layer of a solar cell by spin coating, and then sample ② is obtained after annealing treatment. The preparation of the electron transport layer SnO2 adopts spin coating process, rotates at a speed of 3000 rpm / min for 30 seconds on a spin coater in an environment of relative humidity 20% RH in a fume hood, and is annealed at 150°C for 30 minutes; III. Preparation method of lead iodide solution: In an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl are accurately weighed, mixed according to the stoichiometric ratio, dissolved in a mixed solvent of DMF and DMSO, fully dissolved to form a precursor solution, filtered and stored for use. The lead iodide material is dissolved in a mixed solvent system composed of DMF and DMSO in a volume ratio of 960:40; the heating temperature during the reaction is set to 70°C; magnetic stirring is used for 12 hours; a 0.45 μm organic phase filter head is used for solution filtration; IV. Preparation of lead iodide thin film: First, sample ② is transferred to an argon-filled glove box under vacuum conditions, and a lead iodide thin film is prepared on a spin coater. The specific operation is to drop the PbI2 solution onto the surface of sample ②, and then perform annealing after spin coating to obtain sample ③. First, 50 μL of lead iodide solution is spin-coated statically, and the spin coating process parameters are set to a speed of 2000 rpm / min and a duration of 20 seconds; then annealing is performed at 70°C for 1 minute.

[0032] Comparative Example 1 A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following steps: I. Cleaning and pretreatment of solar cell substrate: The glass substrate is numbered using the initials of the person's name and loaded into the cleaning rack in order. Then, the glass substrate is ultrasonically cleaned with detergent, deionized water, acetone and ethanol in turn. After cleaning, the substrate is dried in an oven and then treated by a UV plasma cleaner to obtain sample ①; II. The sample 1 is fixed in a spin coater, and SnO2 is deposited on the surface of the sample 1 by spin coating to form an electron transport layer of a solar cell, and then sample 2 is obtained after annealing treatment. The preparation of the electron transport layer SnO2 adopts a spin coating process, and the spin coater is rotated at a speed of 3000 rpm / min for 30 seconds in an environment of a ventilated cabinet with a relative humidity of 20% RH, and then annealing treatment is performed at 150°C for 30 minutes; III. Preparation method of lead iodide solution: in an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl are accurately weighed, mixed according to the stoichiometric ratio, dissolved in a DMF and DMSO mixed solvent to form a precursor solution, and stored after filtration treatment. The lead iodide material is dissolved in a mixed solvent system composed of DMF and DMSO with a volume ratio of 960:40; the heating temperature during the reaction is set to 70°C; magnetic stirring is used for 12 hours; and a 0.45 μm organic phase filter head is used for solution filtration; IV. Preparation of additive solution: in an argon atmosphere glove box, EH hydrochloride is dissolved in DMF and stirred thoroughly to obtain an EH solution. The mass fraction of the EH solution is 10wt%, and magnetic stirring is used for 5 hours; V. Preparation steps of lead iodide solution containing additives: in an argon-filled glove box, different concentrations of EH solution are introduced into the PbI2 precursor solution, and the complete dissolution is promoted by thorough stirring, followed by filtration treatment, to finally obtain a PbI2 solution containing EH. The mass fraction of the EH solution is controlled to be 0.3%; VI. Preparation of lead iodide thin film: first, the sample 2 is transferred to an argon-filled glove box under vacuum conditions, and a lead iodide thin film is prepared on a spin coater by spin coating. The specific operation is that the PbI2 solution containing EH is added to the surface of the sample 2, and then annealing is performed after spin coating treatment to obtain sample 3. First, 50 μL of lead iodide solution is treated by static spin coating, and the spin coating process parameters are set as a rotation speed of 2000 rpm / min and a duration of 20 seconds; then annealing treatment is performed at 70°C for 1 minute.

[0033] Comparative Example 2 A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following steps: I. Preparation of additive solution: in an argon atmosphere glove box, EH hydrochloride is dissolved in DMF and stirred thoroughly to obtain an EH solution. The mass fraction of the EH solution is 10wt%, and magnetic stirring is used for 5 hours; II. Preparation of the organic salt solution: In an argon atmosphere glove box, 77 mg, 14 mg and 18 mg of raw materials with a molar ratio of FAI, MAI and MACI were weighed and dissolved in IPA solvent. The solution was heated and stirred at 70°C for 3 hours to obtain a uniform organic salt precursor solution. The organic salt was dissolved in 1 mL of IPA solution. The heating temperature was set to 70°C, and the reaction was continued for 3 hours with magnetic stirring.

[0034] Example 2

[0035] A method for improving the thermal stability of perovskite materials by chemical competitive coordination, comprising the following steps: I. Preparation of the additive solution: In an argon atmosphere glove box, EH hydrochloride was dissolved in DMF and stirred thoroughly. After filtration, an EH solution was obtained. The mass fraction of the EH solution was 10wt%, and the reaction was continued for 5 hours with magnetic stirring. II. Preparation of the organic salt solution: In an argon atmosphere glove box, 77 mg, 14 mg and 18 mg of raw materials with a molar ratio of FAI, MAI and MACI were weighed and dissolved in IPA solvent. The solution was heated and stirred at 70°C for 3 hours to obtain a uniform organic salt precursor solution. The organic salt was dissolved in 1 mL of IPA solution. The heating temperature was set to 70°C, and the reaction was continued for 3 hours with magnetic stirring. III. Preparation of the organic salt solution containing the additive: In an argon-filled glove box, different concentrations of the EH solution were introduced into the FAI precursor solution to promote complete dissolution by thorough stirring. Subsequently, filtration was performed to obtain a FAI solution containing EH. The mass fraction of the EH solution was controlled at 0.3%.

[0036] Comparative Example 3 A method for improving the thermal stability of perovskite materials by chemical competitive coordination, comprising the following steps: I. Cleaning and pretreatment of the solar cell substrate: The glass substrates were numbered using the initials of the person's name and loaded into a cleaning rack in order. Then, the glass substrates were ultrasonically cleaned with detergent, deionized water, acetone and ethanol in sequence. After cleaning, the substrates were dried in an oven and then treated with a UV plasma cleaner to obtain sample ①. II. Sample ① was fixed in a spin coater, and SnO2 was deposited on the surface of sample ① to form an electron transport layer of the solar cell using the spin coating method. Subsequently, sample ② was obtained after annealing treatment. The electron transport layer SnO2 was prepared using the spin coating process, with a rotation speed of 3000 rpm / min for 30 seconds on the spin coater in a ventilated cabinet with a relative humidity of 20% RH, and annealing treatment at 150°C for 30 minutes. III. Preparation of PbI2 solution: In an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl were accurately weighed and mixed according to stoichiometric ratio, then dissolved in a mixed solvent of DMF and DMSO to form a precursor solution. The solution was filtered and stored for use. The PbI2 material was dissolved in a mixed solvent of DMF and DMSO with a volume ratio of 960:40; the heating temperature during the reaction was set to 70°C; magnetic stirring was used for 12 hours; a filter with a pore size of 0.45 μm was used for the solution filtration process; IV. Preparation of organic salt solution: In an argon atmosphere glove box, 77 mg of FAI, 14 mg of MAI and 18 mg of MACI were accurately weighed and dissolved in IPA solvent. The solution was heated and stirred at 70°C for 3 hours to obtain a uniform organic salt precursor solution. The organic salt was dissolved in 1 mL of IPA solution; the heating temperature was set to 70°C, and magnetic stirring was used for 3 hours; V. Preparation of perovskite film: First, sample ② was transferred to an argon-filled glove box under vacuum conditions, and an organic-inorganic hybrid perovskite film was prepared on a spin coater. Specifically, PbI2 solution was added to the surface of sample ②, and after spin coating, annealing was performed to obtain sample ③. Then, sample ③ was placed on the spin coater again, and organic salt solution was quickly added. Finally, sample ④ was obtained by removing it from the glove box and annealing. First, 50 μL of PbI2 solution was spin-coated statically, with a spin speed of 2000 rpm / min and a duration of 20 seconds. Then, annealing was performed at 70°C for 1 minute. Next, 50 μL of organic salt solution was spin-coated dynamically, with a spin speed of 2000 rpm / min and a solution drop time of 10 seconds. Finally, annealing was performed at 150°C for 30 minutes.

[0037] Example 3

[0038] A method for improving the thermal stability of perovskite materials through chemical competitive coordination, comprising the following steps: I. Cleaning and pretreatment of solar cell substrate: The glass substrate was numbered using the initials of the person's name and loaded into a cleaning rack in order. Then, the glass substrate was ultrasonically cleaned with detergent, deionized water, acetone and ethanol in turn. After cleaning, the substrate was dried in an oven and then treated with a UV plasma cleaner to obtain sample ①; II. The sample 1 is fixed in a spin coater, and SnO2 is deposited on the surface of the sample 1 by a spin coating method to form an electron transport layer of a solar cell, and then sample 2 is obtained after annealing treatment. The electron transport layer SnO2 is prepared by a spin coating process, and the spin coater is rotated at a speed of 3000 rpm / min for 30 seconds in a ventilated cabinet with a relative humidity of 20% RH, and annealing treatment is performed at 150°C for 30 minutes; III. Preparation method of lead iodide solution: In an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl are accurately weighed and mixed according to the stoichiometric ratio, and then dissolved in a mixed solvent of DMF and DMSO to form a precursor solution. After filtration treatment, it is stored for use. The lead iodide material is dissolved in a mixed solvent system composed of DMF and DMSO with a volume ratio of 960:40; the heating temperature during the reaction is set to 70°C; magnetic stirring is used for 12 hours; a filter head with a pore size of 0.45 μm is used for solution filtration; IV. Preparation of additive solution: In an argon atmosphere glove box, EH hydrochloride is dissolved in DMF and stirred thoroughly, and then filtered to obtain an EH solution. The mass fraction of the EH solution is 10wt%, and magnetic stirring is used for 5 hours; V. Preparation steps of lead iodide solution containing additives: In an argon-filled glove box, different concentrations of EH solution are introduced into the PbI2 precursor solution, and the complete dissolution is promoted by thorough stirring, followed by filtration treatment, and finally the PbI2 solution containing EH is obtained. The mass fraction of the EH solution is controlled to be 0.3%; VI. Preparation of organic salt solution: In an argon atmosphere glove box, 77 mg, 14 mg and 18 mg of raw materials with a molar ratio of FAI, MAI and MACl are weighed respectively, dissolved in IPA solvent, heated and stirred at 70°C for 3 hours, and a uniform organic salt precursor solution is obtained for use. The organic salt is dissolved in 1 mL of IPA solution; the heating temperature is set to 70°C, and magnetic stirring is used for 3 hours; V. Preparation of perovskite thin film: Firstly, sample ② was transferred into the glove box filled with argon under vacuum condition, and the organic-inorganic hybrid perovskite thin film was prepared on the spin coater. Specifically, the PbI2 solution containing EH was added to the surface of sample ②, and after spin coating treatment, sample ③ was obtained by annealing. Subsequently, sample ③ was placed on the spin coater again, and the organic salt solution was added quickly, and then sample ④ was obtained by annealing after being removed from the glove box. Firstly, 50 μL of lead iodide solution was treated by static spin coating, and the spin coating process parameters were set as follows: rotation speed 2000 rpm / min, and duration 20 seconds; then, annealing treatment was performed at 70°C for 1 minute. Next, 50 μL of organic salt solution was treated by dynamic spin coating, and the rotation speed was kept at 2000 rpm / min during the spin coating process, and the solution was added at the 10th second; then, annealing treatment was performed at 150°C for 30 minutes.

[0039] Comparative Example 4 A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following steps: I. Cleaning and pretreatment of solar cell substrate: The glass substrates were numbered using the initials of the person's name and were loaded into the cleaning rack in order. Then, the glass substrates were ultrasonically cleaned with detergent, deionized water, acetone and ethanol in turn. After cleaning, the substrates were dried in an oven and then treated by a UV plasma cleaner to obtain sample ①; II. Sample ① was fixed on the spin coater, and SnO2 was deposited on the surface of sample ① by spin coating to form the electron transport layer of the solar cell, and then sample ② was obtained by annealing treatment. The electron transport layer SnO2 was prepared by spin coating at a rotation speed of 3000 rpm / min for 30 seconds in a ventilated cabinet with a relative humidity of 20% RH, and then annealed at 150°C for 30 minutes; III. Preparation method of lead iodide solution: In the glove box filled with argon, 691.5 mg of PbI2 and 12.6 mg of CsCl were accurately weighed and mixed according to the stoichiometric ratio, and then dissolved in a mixed solvent of DMF and DMSO to form a precursor solution. After filtration treatment, the solution was stored for use. The lead iodide material was dissolved in a mixed solvent system composed of DMF and DMSO with a volume ratio of 960:40; the heating temperature during the reaction was set to 70°C; magnetic stirring was used for 12 hours; and a 0.45 μm organic phase filter head was used during the filtration of the solution; Four, preparation of organic salt solution: in the glove box under argon atmosphere, the raw materials of molar ratio of FAI, MAI and MACl were weighed as 77 mg, 14 mg and 18 mg respectively, dissolved in IPA solvent, heated and stirred at 70℃ for 3 hours to obtain a uniform organic salt precursor solution, ready for use. The organic salt was dissolved in 1 mL IPA solution; the heating temperature was set to 70℃, and the magnetic stirring was used for continuous reaction for 3 hours; Five, preparation of perovskite thin film: firstly, sample ② was transferred to the glove box filled with argon under vacuum condition, and the organic-inorganic hybrid perovskite thin film was prepared on the spin coater. The specific operation was that PbI2 solution was added to the surface of sample ②, and after spin coating treatment, sample ③ was obtained by annealing. Then, sample ③ was placed on the spin coater again, and the organic salt solution was added quickly, and then it was removed from the glove box for annealing treatment, finally sample ④ was obtained. Firstly, 50 μL of lead iodide solution was treated by static spin coating, and the spin coating process parameters were set as 2000 rpm / min, and the duration was 20 seconds; then it was annealed at 70℃ for 1 minute. Then, 50 μL of organic salt solution was treated by dynamic spin coating, and the rotation speed was kept at 2000 rpm / min during the spin coating process, and the solution was added at the 10th second; then it was annealed at 150℃ for 30 minutes; Six, preparation process of hole transport layer: the Spiro-OMeTAD solution was spin-coated on the surface of sample ④ to form sample ⑤. The composition of the Spiro-OMeTAD solution was 72.3 mg Spiro-OMeTAD, 17.5 μL of Li-TFSI acetonitrile solution with a concentration of 520 mg mL⁻¹ and 28.8 μL of t-BP (dissolved in 1 mL chlorobenzene), and the film was formed by spin coating, and the spin coating rotation speed was set to 4000 rpm, and the duration was 30 seconds; Seven, electrode preparation: the silver (Ag) electrode was deposited on sample ⑤ by vacuum evaporation, and then it was transferred to the rotary evaporator to complete the evaporation process, so as to obtain a complete perovskite solar cell device. The vacuum degree used in the spin evaporation was not less than 1×10 -4 Pa, and the film deposition thickness was controlled to be 80 nm.

[0040] Example 4

[0041] A method for improving the thermal stability of perovskite material by chemical competitive coordination, comprising the following steps: One, cleaning and pretreatment of solar cell substrate: the glass substrate was numbered using the initials of the person's name, and was loaded into the cleaning rack in order. Then, the glass substrate was ultrasonically cleaned with detergent, deionized water, acetone and ethanol in turn. After cleaning, the substrate was dried in an oven, and then treated by a UV plasma cleaner to obtain sample ①; II. The sample 1 was fixed in a spin coater, and SnO2 was deposited on the surface of the sample 1 by spin coating to form an electron transport layer of a solar cell, and then sample 2 was obtained after annealing treatment. The electron transport layer of SnO2 was prepared by spin coating at a speed of 3000 rpm / min for 30 seconds on a spin coater in a fume hood with a relative humidity of 20% RH, and annealing treatment was performed at 150°C for 30 minutes; III. Preparation method of lead iodide solution: In an argon atmosphere glove box, 691.5 mg of PbI2 and 12.6 mg of CsCl were accurately weighed and mixed according to the stoichiometric ratio, and then dissolved in a mixed solvent of DMF and DMSO to form a precursor solution. After filtration, the solution was stored for use. The lead iodide material was dissolved in a mixed solvent system composed of DMF and DMSO with a volume ratio of 960:40; the heating temperature during the reaction was set to 70°C; magnetic stirring was used for 12 hours; a 0.45 μm organic phase filter was used for solution filtration; IV. Preparation of additive solution: In an argon atmosphere glove box, EH was dissolved in DMF and stirred thoroughly, and then filtered to obtain an EH solution. The mass fraction of the EH solution was 10wt%, and magnetic stirring was used for 5 hours; V. Preparation of lead iodide solution containing additives: In an argon-filled glove box, different concentrations of EH solution were introduced into the PbI2 precursor solution, and the solution was stirred thoroughly to promote complete dissolution, and then filtered to obtain a PbI2 solution containing EH. The mass fraction of the EH solution was controlled at 0.1%; VI. Preparation of organic salt solution: In an argon atmosphere glove box, 77 mg of FAI, 14 mg of MAI, and 18 mg of MACl were weighed according to the molar ratio, and then dissolved in IPA solvent, heated and stirred at 70°C for 3 hours to obtain a uniform organic salt precursor solution. The organic salt was dissolved in 1 mL of IPA solution; the heating temperature was set to 70°C, and magnetic stirring was used for 3 hours; Seven, preparation of perovskite thin film: firstly, sample ② is transferred to the glove box filled with argon under vacuum conditions, and an organic-inorganic hybrid perovskite thin film is prepared on the spin coater. The specific operation is to drop PbI2 solution onto the surface of sample ②, and after spin coating treatment, annealing is performed to obtain sample ③. Then, sample ③ is placed on the spin coater again, and organic salt solution is quickly added, and then it is removed from the glove box for annealing treatment, and finally sample ④ is obtained. Firstly, 50 μL of lead iodide solution is treated by static spin coating, and the spin coating process parameters are set as follows: rotation speed 2000 rpm / min, duration 20 seconds; then annealing treatment is carried out at 70°C for 1 minute. Then, 50 μL of organic salt solution is treated by dynamic spin coating, and the rotation speed is kept at 2000 rpm / min during the spin coating process, and the solution is added at the 10th second; then annealing treatment is carried out at 150°C for 30 minutes; Eight, preparation process of hole transport layer: the Spiro-OMeTAD solution is spin-coated on the surface of sample ④ to form sample ⑤. The composition of the Spiro-OMeTAD solution is 72.3 mg Spiro-OMeTAD, 17.5 μL of Li-TFSI acetonitrile solution with a concentration of 520 mg mL⁻¹, and 28.8 μL of t-BP (dissolved in 1 mL of chlorobenzene), and the film is formed by spin coating, and the spin coating rotation speed is set to 4000 rpm, and the duration is 30 seconds; Nine, electrode preparation: silver (Ag) electrode is deposited on sample ⑤ by vacuum evaporation, and then it is transferred to the rotary evaporator to complete the evaporation process, so as to obtain a complete perovskite solar cell device. The vacuum degree used in spin evaporation is not less than 1×10 -4 Pa, and the film deposition thickness is controlled to be 80 nm.

[0042] Example 5

[0043] The difference between example 5 and example 4 is that the mass fraction of EH solution in step five is controlled to be 0.3%.

[0044] Example 6

[0045] The difference between example 5 and example 4 is that the mass fraction of EH solution in step five is controlled to be 0.5%.

[0046] The electrostatic potential of EH (see Figure 2 ), it can be seen that the negatively charged carbonyl group in EH combines with PbI2 to form a Pb–O coordination bond, thereby promoting the dissociation of DMSO from the solvent coordination environment and realizing the competitive coordination between ligands.

[0047] The crystallinity of lead iodide films prepared in comparative example 1 and example 1 is compared (see Figure 3), it can be seen that the EH in the preparation of Example 1 is modified to the PbI2 thin film, and the results show that the diffraction ring intensity of DMSO-PbI2 is significantly weakened, indicating that the EH plays a significant role in the system, and successfully replaces the PbI2 from the DMSO-PbI2 complex.

[0048] The NMR of the solutions prepared in Comparative Example 2 and Example 2 is compared (see Figure 4 ), it can be seen that the hydrogen bond of the EH-FAI solution in the preparation of Example 2 occurs, which proves that the FAI significantly approaches the EH through hydrogen bond, and effectively promotes the formation of the perovskite structure.

[0049] The perovskite thin film crystals prepared in Comparative Example 3 and Example 3 are compared (see Figure 5 ), it can be seen that the perovskite thin film prepared in Example 3 occurs high-quality crystallization, which confirms that the perovskite thin film can spontaneously form a high-quality crystalline structure.

[0050] The photoelectric conversion efficiency of the perovskite devices prepared in Comparative Example 4, Example 4, Example 5 and Example 6 is compared (see Figure 6 ), it can be seen that the EH in the preparation of Example 5 has a significant effect on the performance improvement of the perovskite device, and verifies the performance improvement of the perovskite device.

[0051] The perovskite devices prepared in Comparative Example 4 and Example 5 are normalized efficiency analysis of PCE change under different aging time, which verifies the significant improvement of the thermal stability of the device (see Figure 7 ).

[0052] The present application is applicable to a method for improving the thermal stability of perovskite material by chemical competitive coordination, which introduces competitive coordination chemistry as a universally applicable strategy to effectively eliminate solvent residues in perovskite photovoltaic devices. Through the ingenious multifunctional design of EH, a significant synergistic effect is achieved: the carbonyl group replaces DMSO, promotes the arrangement of FA⁺ guided by amine, fills the chloride vacancy, and wraps the hydrophobic grain boundary. These comprehensive effects not only significantly inhibit the formation of defects, reducing the trap density by 43.4%, but also impart excellent thermal degradation resistance. Therefore, the device achieves a power conversion efficiency of 26.06%, while having excellent stability: maintaining more than 90% of the initial efficiency at 85°C (ISOS-L-3) for 1200 hours. The strategic use of a two-site passivation agent as a crystallization regulator reveals the great potential of molecular reuse in overcoming the long-standing trade-off between efficiency and stability of solution-processed semiconductor materials.

[0053] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A method for improving the thermal stability of a perovskite material by chemical competitive coordination, characterized in that: The method comprises the following steps: I. cleaning and pretreating a solar cell substrate to obtain sample 1; II. preparing an electron transport layer: fixing the sample 1 on a spin coater, depositing SnO2 on the surface of the sample 1 by spin coating to form an electron transport layer of the solar cell, and then obtaining sample 2 through annealing treatment; III. a preparation method of a lead iodide solution: mixing PbI2 and CsCl in a stoichiometric ratio in an argon atmosphere glove box, dissolving them in a DMF and DMSO mixed solvent to form a precursor solution, and storing the precursor solution after filtration treatment; IV. preparation of an additive solution: dissolving ethylhexadimethylguanidine hydrochloride in DMF in an argon atmosphere glove box and stirring thoroughly, and obtaining an EH solution after filtration; V. preparation of a lead iodide solution containing an additive: introducing an EH solution with different concentrations into the PbI2 precursor solution in an argon-filled glove box, promoting complete dissolution by stirring thoroughly, and then performing filtration treatment to obtain a PbI2 solution containing the EH; VI. preparation of an organic salt solution: dissolving formamidinium iodide (FAI), methylammonium iodide (MAI) and methylammonium chloride (MACl) raw materials in isopropanol solvent in an argon atmosphere glove box, heating and stirring to obtain a uniform organic salt precursor solution; VII. preparation of a perovskite film: firstly, transferring the sample 2 to an argon-filled glove box under vacuum conditions, adding the additive-containing lead iodide solution of step V to the surface of the sample 2, performing spin coating treatment, and then annealing to obtain sample 3; then, placing the sample 3 on a spin coater again, quickly adding the organic salt solution, and then removing the sample 3 from the glove box for annealing treatment to obtain sample 4; VIII. preparation of a hole transport layer: spin coating a Spiro-OMeTAD solution on the surface of the sample 4 to form sample 5; IX. electrode preparation: depositing a silver electrode on the sample 5 by vacuum evaporation, transferring the sample 5 to a rotary evaporator to complete the evaporation process, and thus obtaining a complete perovskite solar cell device.

2. The method for improving the thermal stability of perovskite material by chemical competitive coordination according to claim 1, characterized in that: In step I, the glass substrate is first cleaned in a detergent, deionized water, acetone and ethanol by ultrasonic cleaning, then the cleaned glass substrate is dried, and finally the dried substrate is treated by a UV plasma cleaning instrument; the glass substrate used is an ITO conductive glass sheet.

3. The method for improving the thermal stability of perovskite material by chemical competitive coordination according to claim 1, characterized in that: In step II, the electron transport layer SnO2 is prepared by spin coating at a speed of 3000 rpm / min for 30 seconds on a spin coater in a ventilated cabinet with a relative humidity of 20% RH, and annealing at 150°C for 15-30 minutes.

4. The method for improving the thermal stability of perovskite material by chemical competitive coordination according to claim 1, characterized in that: In step III, the lead iodide material is dissolved in a mixed solvent system composed of DMF and DMSO in a volume ratio of 960:40; the heating temperature during the reaction is set to 70-80°C; magnetic stirring is used for 10-12 hours.

5. The method for improving the thermal stability of perovskite material by chemical competitive coordination of claim 1, characterized in that: In step IV, the mass fraction of the EH solution is 10wt%, and magnetic stirring is used for 3-5 hours.

6. The method for improving the thermal stability of perovskite material by chemical competitive coordination of claim 1, wherein: In step V, the mass fraction of the EH solution is controlled to be between 0.1% and 0.5%.

7. The method for improving the thermal stability of perovskite material by chemical competitive coordination of claim 1, wherein: In step six, formamidinium iodide (FAI), methylammonium iodide (MAI) and methylammonium chloride (MACI) are dissolved in IPA solution in a molar ratio of 5:1:3; the heating temperature is set to 70-80°C, and the reaction is continued for 1-3 hours with magnetic stirring.

8. The method for improving the thermal stability of perovskite materials through chemical competitive coordination according to claim 1, characterized in that: In step eight, the composition of the Spiro-OMeTAD solution is Spiro-OMeTAD, Li-TFSI acetonitrile solution and t-BP in a molar ratio of 1:0.54:3.4, and a spin coating method is used to form a film, with a spin coating speed of 4000 rpm and a duration of 30 seconds.

9. The method for improving the thermal stability of perovskite materials through chemical competitive coordination according to claim 1, characterized in that: In step nine, the vacuum degree used in spin evaporation is not less than 1 x 10 -4 Pa, and the thickness of the thin film deposition is controlled to be 80-100 nm.

Images