Perovskite material for improving water stability based on bidentate ligand covalent passivation and preparation method and application thereof
By passivating MAPbI3 with bidentate ligands of mercaptocarboxylic acid, the problem of easy decomposition of MAPbI3 in humid environments is solved, significantly improving its photoelectric properties and water stability, and broadening its application in humid environments and aqueous solutions.
Patent Information
- Application Number
- CN202511062396.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-11-21
AI Technical Summary
MAPbI3 perovskite materials are prone to decomposition in humid environments, and existing passivation strategies cannot effectively improve their water stability, resulting in a decrease in photoelectric conversion efficiency and failing to meet long-term application requirements.
Using mercaptocarboxylic acid as a bidentate ligand, Pb-S covalent bonds are formed between the mercapto group and Pb2+, and amide bonds are formed using the EDC/NHS catalytic system, thereby achieving two-site covalent passivation of the MAPbI3 lattice and enhancing the water stability of the material.
It significantly improves the photoelectric properties and water stability of MAPbI3, and extends its service life in aqueous solution. The photoelectric properties are improved by more than 75%, and the water stability is such that it does not decompose after continuous storage in aqueous solution for 7 days.
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Figure CN120987774A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optoelectronic functional materials technology, specifically relating to a perovskite material with improved water stability based on bidentate ligand covalent passivation, its preparation method, and its application. Background Technology
[0002] In recent years, the organic-inorganic hybrid perovskite material MAPbI3 has shown broad application prospects in fields such as solar cells, photodetectors, light-emitting diodes, and photoelectrochemical biosensors due to its excellent photoelectric conversion efficiency (PCE>23%), high carrier mobility, tunable bandgap, and low-cost fabrication process. However, the A-site cation MA in MAPbI3... + Its high water solubility causes the material to rapidly decompose into MAI and PbI2 in humid environments, severely limiting its practical applications. Experiments show that at 25°C and 30-50% relative humidity, the photoelectric conversion efficiency of perovskite solar cells (PSCs) can drop by nearly 90% within a few days.
[0003] Currently, common strategies for improving the water stability of MAPbI3 include encapsulation technology and hydrophobic material coating. However, these methods only reduce water contact and cannot fundamentally solve the hydrolysis problem of the material. Furthermore, they may hinder carrier transport or lead to leakage and contamination due to incomplete encapsulation. In recent years, surface ligand passivation technology has gradually attracted attention. For example, small molecules such as amino acids are used to modify the perovskite surface, passivating X-site defects through carboxyl groups and supplementing A-site defects through hydrogen bonds with amino groups, thereby improving stability. In addition, studies have reported the use of bidentate ligands (such as 2-aminoethanethiol) to interact with Pb via thiol groups (-SH). 2+ Hydrogen bonds are formed between the amino group (-NH2) and MAI, stabilizing MAPbI3 in aqueous solution for 10 minutes. However, the hydrogen bonding is weak, resulting in limited passivation; the perovskite material still decomposes after 10 minutes, indicating that existing passivation strategies cannot meet the requirements for long-term water stability. Therefore, improving the intrinsic stability of MAPbI3 in aqueous solution has become a key research challenge.
[0004] To address the aforementioned problems, this invention proposes a novel method for passivating MAPbI3 perovskite based on bidentate ligands of thiocarboxylic acids using covalent bonds. This method utilizes thiocarboxylic acids, small molecules possessing both thiol (-SH) and carboxyl (-COOH) groups, as passivating agents, through the interaction of -SH and Pb... 2+ The combination forms Pb-S bonds, as well as -COOH and methylammonium ions (MA). +Acid bonds are formed between 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to stabilize MAPbI3 perovskite. Compared to traditional hydrogen bond passivation, the covalent bond energy is higher, which significantly enhances the intrinsic stability of perovskite in aqueous solutions, extends its lifespan, and improves its photoelectric properties. This technology provides a breakthrough solution for the application of perovskite materials in humid environments or liquid-phase sensing. Summary of the Invention
[0005] To improve the water stability of MAPbI3 perovskite, this invention uses mercaptocarboxylic acid to passivate MAPbI3, developing a perovskite material and its preparation method based on bidentate ligand covalent passivation to enhance water stability. The bidentate ligand of mercaptocarboxylic acid is introduced into the MAPbI3 perovskite lattice, and the mercapto group interacts with Pb... 2+ The proposed method involves forming Pb-S covalent bonds and simultaneously using an EDC / NHS catalytic system to react the carboxyl groups with ammonium carboxyl ions to form amide bonds. This simultaneously immobilizes the A and X sites of MAPbI3, achieving dual-site covalent bond passivation of the perovskite lattice and significantly enhancing the material's stability in aqueous solutions, thus forming a water-stable mercaptocarboxylic acid-MAPbI3 perovskite material. Furthermore, the proposed preparation method can significantly improve the photoelectric properties of the perovskite material.
[0006] The method for preparing perovskite materials based on bidentate ligand covalent passivation to improve water stability according to the present invention includes the following steps:
[0007] Step 1: Weigh 0.01-0.05 mmol of PbI2 powder, disperse it in 10 mL of N,N-dimethylformamide (DMF), stir for 10-60 min to form a uniform 1-5 mM light yellow PbI2 solution, heat it in a water bath to 30-70 °C to obtain solution A;
[0008] Step 2: Weigh 0.01-0.05 mmol of methylamine iodide (MAI) crystals and add them to solution A. Continue stirring at 30-70°C for 10-60 min to obtain the precursor solution of MAPbI3.
[0009] Step 3: Prepare a DMF solution containing 0.1M EDC and 0.1M NHS as dispersant A;
[0010] Step 4: Weigh 0.01-0.06 mmol of mercaptocarboxylic acids (2-11 carbons, such as mercaptoacetic acid (TGA), mercaptopropionic acid (MPA), mercaptobutyric acid (MBA), mercaptovalerate (MAA), mercaptohexanoic acid (MHA), etc.) and dissolve them in 10 mL of dispersant A, and activate at room temperature for 10-60 min.
[0011] Step 5: Add the activated thiocarboxylic acid to the MAPbI3 precursor solution and stir continuously at 30–70°C for 1–4 hours to allow the thiol (-SH) to react with Pb. 2+ Formation of Pb-S bonds, carboxyl groups (-COOH), and MA + An amide bond is formed; the molar ratio of thiocarboxylic acid to MAPbI3 is (1-4):1;
[0012] Step 6: After the reaction is complete, allow it to cool naturally to room temperature. The resulting solution is a MAPbI3 solution passivated with thiocarboxylic acid (thiocarboxylic acid-MAPbI3 solution).
[0013] Step 7: Add diethyl ether dropwise as an antisolvent to the mercaptocarboxylic acid-MAPbI3 solution. A large amount of white precipitate is observed to form. After centrifugation at 4000-8000 rpm for 3-30 min, dry in a vacuum drying oven at 20-60℃ for 2-12 h to obtain black mercaptocarboxylic acid-MAPbI3 solid.
[0014] The beneficial effects of this invention are:
[0015] 1) This invention performs simultaneous covalent passivation of MAPbI3 at two sites using bidentate ligand mercaptocarboxylic acid, which significantly reduces defects on the surface of MAPbI3 and greatly increases the photocurrent value of MAPbI3, improving its photoelectric performance by at least 75%.
[0016] 2) The thiol carboxylic acid-MAPbI3 synthesized in this invention significantly improves the water stability of MAPbI3. It can be stored in aqueous solution for 7 days without decomposition, and the photoelectric properties remain at more than 90% of the original sample. This broadens the photoelectric applications of MAPbI3 in humid environments and aqueous solutions, such as solar cells, photoelectrochemical sensors and other optoelectronic devices.
[0017] 3) The synthesis method of this invention is simple and easy to introduce bidentate ligand mercaptocarboxylic acid into the preparation method, so that mercaptocarboxylic acid can enter the crystal lattice of MAPbI3 and passivate MAPbI3 through a bicovalent bond strategy. The synthesis cost is low and it is easy to prepare on a large scale. Attached Figure Description
[0018] Figure 1 Schematic diagram of MAPbI3 perovskite passivated by thiocarboxylic acid covalent bonds;
[0019] Figure 2 SEM images of the original MAPbI3 and Examples 1-5;
[0020] Figure 3 Photocurrent response diagrams of the original MAPbI3 and Examples 1-5 under continuous illumination over 10 minutes;
[0021] Figure 4 The image shows a comparison of the XRD patterns of the original MAPbI3 and Examples 1-5 before and after soaking in aqueous solution for 7 days.
[0022] Figure 5 Photocurrent response diagrams of the original MAPbI3 and Examples 1-5 before and after soaking in aqueous solution for 7 days; Detailed Implementation
[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0024] Example 1
[0025] A method for preparing water-stable TGA-MAPbI3 perovskite:
[0026] The molar ratio of thioglycolic acid to MAPbI3 is 1.2:1, and the specific steps include:
[0027] (1) Weigh 0.005 mmol of PbI2 powder, disperse it in 10 mL of DMF, stir for 10 min to form a uniform light yellow solution, heat it in a water bath to 70 °C, add 0.005 mmol of MAI crystals, and continue stirring at 70 °C for 30 min to obtain the precursor solution of MAPbI3.
[0028] (2) Weigh 0.006 mmol of TGA, dissolve it in 10 mL of DMF solution containing 0.1 M EDC and 0.1 M NHS, and activate it at room temperature for 30 min;
[0029] (3) The activated TGA solution was added to the precursor solution of MAPbI3 and stirred continuously at 70°C for 4 hours. After cooling to room temperature, TGA-MAPbI3 solution was obtained.
[0030] Example 2
[0031] A method for preparing water-stable MPA-MAPbI3 perovskite:
[0032] Mercaptopropionic acid:MAPbI3 = 1.2:1 (molar ratio), specifically including the following steps:
[0033] The difference from Example 1 is that MPA is used in step (2). The remaining process steps and parameters are the same as in Example 1.
[0034] Example 3
[0035] A method for preparing water-stable MBA-MAPbI3 perovskite:
[0036] Mercaptobutyric acid:MAPbI3 = 1.2:1 (molar ratio), specifically including the following steps:
[0037] The difference from Example 1 is that MBA is used in step (2). The remaining process steps and parameters are the same as in Example 1.
[0038] Example 4
[0039] A method for preparing water-stable MAA-MAPbI3 perovskite:
[0040] Mercaptovalerate:MAPbI3 = 1.2:1 (molar ratio), specifically including the following steps:
[0041] The difference from Example 1 is that MAA is used in step (2). The remaining process steps and parameters are the same as in Example 1.
[0042] Example 5
[0043] A method for preparing water-stable MHA-MAPbI3 perovskite:
[0044] The molar ratio of mercaptohexanoic acid to MAPbI3 is 1.2:1, and the specific steps include:
[0045] The difference from Example 1 is that MHA is used in step (2). The remaining process steps and parameters are the same as in Example 1.
[0046] Comparative Example 1
[0047] The original MAPbI3 perovskite differs from that in Example 1 only in that EDC and NHS-activated mercaptocarboxylic acid are not added, i.e., steps (2) and (3) are not performed. All other process steps and parameters are the same as in Example 1.
[0048] Example 6
[0049] Photoelectric performance testing:
[0050] Based on the MAPbI3 perovskite materials modified with different thiocarboxylic acids (TGA, MPA, MBA, MAA, MHA) prepared in Examples 1 to 5, 20 μL of MAPbI3 solutions modified with different thiocarboxylic acids were dropped onto a clean ITO electrode surface, followed by the addition of 20 μL of diethyl ether. The electrodes were then dried under an infrared lamp to obtain MAPbI3 electrodes modified with different thiocarboxylic acids (TGA-MAPbI3 film / ITO electrode, MPA-MAPbI3 film / ITO electrode, MBA-MAPbI3 film / ITO electrode, MAA-MAPbI3 film / ITO electrode, MHA-MAPbI3 film / ITO electrode). The photoelectric properties were studied using a 300W xenon lamp equipped with a 420 nm UV filter in 0.1 M Tris-HCl buffer (pH = 7.4) on an electrochemical workstation (CHI 660D, Shanghai Chenhua).
[0051] Technical effects:
[0052] Figure 2 Comparison of SEM morphologies of pristine MAPbI3 and MAPbI3 modified with different thiol carboxylic acids (TGA, MPA, MBA, MAA, MHA). Figure 2 A) It has a fibrous structure with pinholes on the surface (illustration), which easily allows water molecules to penetrate; TGA-MAPbI3 ( Figure 2 B) transforms into a granular morphology, but pinholes and cracks still exist; MPA-MAPbI3 ( Figure 2 C) Exhibits a dense, smooth granular surface with no obvious defects, exhibiting the best resistance to water intrusion. With increasing carbon chain length (MBA, MAA, MHA), Figure 2 The morphology of D-2F gradually changes to a mixture of fibers and particles, the particle size decreases, and the number of pinholes and cracks increases.
[0053] Figure 3The photocurrent response of pristine MAPbI3 and MAPbI3 modified with different thiol carboxylic acids (TGA, MPA, MBA, MAA, MHA) under 10 min continuous illumination is shown. Compared with pristine MAPbI3 (-10.2 μA, curve a), the initial photocurrent of TGA-MAPbI3 increased by 2.1 times (21.1 μA, curve b), MPA-MAPbI3 by 2.5 times (25.6 μA, curve c), MBA-MAPbI3 by 2.2 times (22.3 μA, curve d), MAA-MAPbI3 by 1.9 times (19.3 μA, curve e), and MHA-MAPbI3 by 1.8 times (17.9 μA, curve f). In terms of the attenuation of photocurrent, compared with the original MAPbI3 (29.5%, curve a), TGA-MAPbI3 retained 63.3% of its initial photocurrent after 10 min of continuous illumination in aqueous solution (curve b), MPA-MAPbI3 retained 95.6% (curve c), MBA-MAPbI3 retained 80.3% (curve d), MAA-MAPbI3 retained 76.2% (curve e), and MHA-MAPbI3 retained 66.5% (curve f). It can be seen that passivation of MAPbI3 using mercaptocarboxylic acid significantly improves both photocurrent and stability.
[0054] Figure 4 The XRD patterns of pristine MAPbI3 and MAPbI3 modified with different thiol carboxylic acids (TGA, MPA, MBA, MAA, MHA) after immersion in aqueous solution for 7 days are compared with those before immersion. It can be seen that pristine MAPbI3 is almost completely decomposed into PbI2 after 7 days of immersion. TGA-MAPbI3 shows characteristic peaks of PbI2 at 12.7°, 25.9°, 34.3°, and 39.5°. MPA-MAPbI3 shows a characteristic peak of PbI2 only at 25.9°. MBA-MAPbI3 shows characteristic peaks of PbI2 at both 12.7° and 25.9°. MAA-MAPbI3 and MHA-MAPbI3 show characteristic peaks of PbI2 at 12.7°, 25.9°, 34.3°, and 39.5°, with an increasing trend. It can be seen that compared with pristine MAPbI3, the degree of decomposition of thiol carboxylic acid-MAPbI3 is significantly reduced, and its water stability is significantly improved.
[0055] Figure 5This chart compares the initial photocurrent of pristine MAPbI3 and MAPbI3 modified with different thiol carboxylic acids (TGA, MPA, MBA, MAA, and MHA) before and after immersion in aqueous solution for 7 days. After immersion in aqueous solution for 7 days, the initial photocurrent of pristine MAPbI3 decreased to 50.5% of its original value, TGA-MAPbI3 decreased to 68.7%, MPA-MAPbI3 decreased to 93.0%, MBA-MAPbI3 decreased to 71.3%, MAA-MAPbI3 decreased to 62.2%, and MHA-MAPbI3 decreased to 40.8%. It can be seen that compared to pristine MAPbI3, thiol carboxylic acid-modified MAPbI3 maintains better stability after 7 days of storage in aqueous solution.
[0056] This invention utilizes the bidentate ligand thiol carboxylic acid to simultaneously covalently passivate the two sites of MAPbI3 perovskite, significantly improving the insufficient water stability of MAPbI3 perovskite. Furthermore, simultaneous covalent passivation promotes a more complete MAPbI3 structure, significantly enhancing its photoelectric properties.
[0057] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A perovskite material with enhanced water stability based on bidentate ligand covalent passivation, characterized in that: Thiocarboxylic acids were selected to passivate MAPbI3.
2. The perovskite material with improved water stability based on bidentate ligand covalent passivation as described in claim 1, characterized in that: Introducing a bidentate ligand of mercaptocarboxylic acid into the MAPbI3 perovskite lattice allows for interaction between the mercapto (-SH) group and Pb. 2+ Pb-S covalent bonds are formed, and simultaneously, the carboxyl group (-COOH) reacts with the methylammonium ion (MA) via a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) / N-hydroxysuccinimide (NHS) catalytic system. + The reaction forms amide bonds, achieving two-site covalent passivation of the perovskite lattice, forming a water-stable mercaptocarboxylic acid-MAPbI3 perovskite material.
3. A method for preparing perovskite materials with enhanced water stability based on bidentate ligand covalent passivation as described in any one of claims 1 to 2, characterized in that, The method includes the following steps: Step 1: Weigh 0.01-0.05 mmol of PbI2 powder, disperse it in 10 mL of N,N-dimethylformamide (DMF), stir for 10-60 min to form a uniform 1-5 mM light yellow PbI2 solution, heat it in a water bath to 30-70 °C to obtain solution A; Step 2: Weigh 0.01-0.05 mmol of methylamine iodide (MAI) crystals and add them to solution A. Continue stirring at 30-70°C for 10-60 min to obtain the precursor solution of MAPbI3. Step 3: Prepare a DMF solution containing 0.1M EDC and 0.1M NHS as dispersant A; Step 4: Weigh 0.01-0.06 mmol of mercaptocarboxylic acids (2-11 carbons, such as mercaptoacetic acid (TGA), mercaptopropionic acid (MPA), mercaptobutyric acid (MBA), mercaptovalerate (MAA), mercaptohexanoic acid (MHA), etc.) and dissolve them in 10 mL of dispersant A, and activate at room temperature for 10-60 min. Step 5: Add the activated thiocarboxylic acid to the MAPbI3 precursor solution and stir continuously at 30–70°C for 1–4 hours to allow the thiol (-SH) to react with Pb. 2+ Formation of Pb-S bonds, carboxyl groups (-COOH), and MA + An amide bond is formed; the molar ratio of the thiocarboxylic acid to MAPbI3 is (1-4):1; Step 6: After the reaction is complete, allow it to cool naturally to room temperature. The resulting solution is a MAPbI3 solution passivated with thiocarboxylic acid (thiocarboxylic acid-MAPbI3 solution). Step 7: Add diethyl ether solution dropwise to the mercaptocarboxylic acid-MAPbI3 solution. A large amount of white precipitate is observed to form. After centrifugation at 4000-8000 rpm for 3-30 min, dry in a vacuum drying oven at 20-60℃ for 2-12 h to obtain black mercaptocarboxylic acid-MAPbI3 solid.
4. The application of a perovskite material based on bidentate ligand covalent passivation to enhance water stability as described in any one of claims 1 to 2, or the perovskite material based on bidentate ligand covalent passivation to enhance water stability prepared by the preparation method described in claim 3, in optoelectronic devices, photocatalysis, and photoelectrochemical sensing.