Method for passivating performance of perovskite solar cell
By introducing ionic liquid additives into perovskite solar cells for dual passivation of the bulk and interface, the defect problems of perovskite solar cells have been solved, the device performance and stability have been improved, and their commercialization process has been promoted.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI UNIV
- Filing Date
- 2026-04-16
- Publication Date
- 2026-05-19
AI Technical Summary
CH3NH3PbI3 perovskite solar cells suffer from numerous defects and are sensitive to humidity and thermal stress, resulting in low device performance and insufficient long-term stability, which hinders their commercialization.
By introducing ionic liquids as additives, the synergistic effect of cations and anions can achieve dual passivation of the bulk and interface of the perovskite light-absorbing layer, passivating grain boundaries and bulk defects, and enhancing the hydrophobicity of the film.
It significantly improves open-circuit voltage and photoelectric conversion efficiency, enhances long-term device stability, and is suitable for perovskite solar cells with both upright and inverted structures, thus promoting their commercialization.
Smart Images
Figure CN122069931A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar cell technology, and specifically to a method for using ionic liquids as modifying materials to perform bulk and interfacial passivation of the perovskite light-absorbing layer of perovskite solar cells. Background Technology
[0002] Organic-inorganic hybrid metal halide perovskite materials, especially CH3NH3PbI3 (methylamine lead iodide), have become a research hotspot in the photovoltaic field over the past decade due to their excellent photoelectric properties, such as high light absorption coefficient, long carrier diffusion length, low exciton binding energy, and bipolar charge transport characteristics. Perovskite solar cells (PSCs) based on CH3NH3PbI3 have developed rapidly, with their certified photoelectric conversion efficiency exceeding 25%, demonstrating enormous potential to surpass traditional crystalline silicon solar cells.
[0003] However, CH3NH3PbI3 perovskite solar cells still face several key challenges on their path to commercialization. First, polycrystalline CH3NH3PbI3 films prepared using solution methods contain numerous defects, including uncoordinated Pb²⁺, halogen vacancies, and dangling bonds at grain boundaries. These defects act as nonradiative recombination centers for photogenerated carriers, leading to an open-circuit voltage (V0). OC The loss and decrease in fill factor severely restrict further improvement in device efficiency. Secondly, CH3NH3PbI3 material is sensitive to humidity and thermal stress, and is prone to decomposition under environmental conditions, resulting in insufficient long-term operational stability of the device, which has become a major obstacle to its industrialization.
[0004] To overcome these bottlenecks, researchers have developed various strategies, among which additive engineering has attracted considerable attention due to its ease of operation and significant effects. Additives are introduced into perovskite precursor solutions to regulate the crystallization process, passivate defects, and improve film quality. Summary of the Invention
[0005] To overcome the problem of low device performance caused by numerous defects in existing CH3NH3PbI3 perovskite solar cells, this invention aims to provide a simple and effective method to improve their performance. This invention introduces an ionic liquid as an additive to the perovskite precursor solution, achieving dual passivation of the bulk and interface of the perovskite light-absorbing layer, significantly improving the device's open-circuit voltage, photoelectric conversion efficiency, and long-term stability.
[0006] This invention utilizes the synergistic effect of different functional groups in ionic liquids. The cations in the ionic liquid can regulate the crystallization process of perovskite, promoting the formation of PbI2 particles at the grain boundaries on the perovskite film surface. These PbI2 particles not only effectively passivate defects at the grain boundaries but also act as p-type semiconductors, enhancing hole transport capabilities. Simultaneously, the anions can interact with uncoordinated Pb²⁺, passivating cation defects within the perovskite bulk phase and reducing non-radiative recombination centers. Furthermore, the hydrophobic groups in the ionic liquid can improve the overall hydrophobicity of the perovskite film, thereby enhancing the device's humidity stability. This synergistic dual passivation strategy effectively reduces defect density, suppresses non-radiative recombination, improves carrier lifetime and mobility, ultimately achieving a significant increase in open-circuit voltage and fill factor, and greatly improving the long-term stability of the device.
[0007] The present invention discloses a method for passivating and modifying the performance of perovskite solar cells, which uses ionic liquids as additives to perform bulk and interfacial passivation modification on the perovskite light-absorbing layer, specifically including the following steps:
[0008] (1) Under a protective atmosphere, add the ionic liquid to the perovskite precursor solution, stir to dissolve, and filter after it is evenly mixed to obtain a perovskite solution containing additives.
[0009] (2) Under a protective atmosphere, the perovskite solution obtained in step 1 is coated onto the substrate, and an anti-solvent is added during spin coating to obtain a perovskite wet film.
[0010] (3) Under a protective atmosphere, the perovskite wet film prepared in step 2 is heated and annealed, and then naturally cooled to room temperature to obtain the perovskite light-absorbing layer of the perovskite solar cell modified by ionic liquid passivation.
[0011] The ionic liquid is 1-butyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, etc.
[0012] The perovskite is CH3NH3PbI3, and its precursor solution is prepared by dissolving CH3NH3I and PbI2 in an organic solvent at a molar ratio of 1:1, with a solution concentration of 1.0 mmol / mL to 1.8 mmol / mL. The organic solvent includes, but is not limited to, one or more of N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, and N-methylpyrrolidone.
[0013] In step (1), the concentration of the ionic liquid added to the perovskite precursor solution is 0.1-1 mmol / mL.
[0014] In step (2), the substrate is a conductive glass with an electron transport layer deposited on it; the electron transport layer is TiO2, SnO2, ZnO or WO3; the conductive glass is FTO conductive glass or ITO conductive glass.
[0015] In step (2), the antisolvent includes, but is not limited to, chlorobenzene, toluene, diethyl ether, methyl formate, methyl acetate, ethyl acetate, etc.; the spin coating of the perovskite solution is completed in one step; the spin coating rate is 3000-5000 rpm / min, and the spin coating time is 20-30 s.
[0016] In step (3), the annealing temperature is 100 ℃-130 ℃ and the annealing time is 10-25 min, preferably annealing at 130 ℃ for 10 min.
[0017] The present invention has the following advantages compared with existing methods:
[0018] (1) In this invention, ionic liquid is introduced as an additive into the perovskite precursor solution. By utilizing the synergistic effect of its cations and anions, dual passivation of bulk defects and interfacial grain boundary defects of perovskite films is achieved, which is an efficient modification strategy.
[0019] (2) This method can not only significantly improve the open-circuit voltage and photoelectric conversion efficiency of the battery, but also greatly improve the long-term stability of the device by enhancing the hydrophobicity of the thin film.
[0020] (3) This method is simple to operate, requiring only the addition of a small amount of additives to the precursor solution, without the need for additional process steps, and is easy to achieve large-scale industrial production. At the same time, this method can be widely applied to various types of MAPbI3 perovskite solar cells, such as upright, inverted, and carbon-based structures, and has broad application prospects, which is conducive to promoting the commercialization of perovskite solar cells. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of a carbon-based CH3NH3PbI3 perovskite solar cell prepared according to Example 1 of this invention;
[0022] Figure 2 The X-ray diffraction patterns are those of the control and the perovskite films treated with 1-butyl-3-methylimidazolium trifluoroacetate prepared according to Example 1.
[0023] Figure 3 The steady-state photoluminescence spectra of the control and the perovskite films treated with 1-butyl-3-methylimidazolium trifluoroacetate prepared according to Example 1 are shown.
[0024] Figure 4The JV curves are for the control and the champion device treated with 1-butyl-3-methylimidazolium trifluoroacetate according to Example 1. Detailed Implementation
[0025] To further understand the method of the present invention, preferred embodiments of the present invention are now provided, and detailed descriptions are given below with accompanying drawings.
[0026] Example 1:
[0027] Step 1, Substrate preparation: The etched FTO conductive glass is ultrasonically cleaned for 30 min each with detergent, deionized water, ethanol and isopropanol, then dried with nitrogen and treated with ultraviolet ozone for 20 min.
[0028] Step 2, Electron transport layer preparation: A SnO2 hydrocolloid dispersion (3 wt%) was spin-coated onto the treated FTO substrate at a spin speed of 5000 rpm / min for 30 s, and then annealed on a hot plate at 150 ℃ for 20 min to obtain the SnO2 electron transport layer. Subsequently, the substrate was treated again with UV ozone for 20 min and transferred to a nitrogen glove box.
[0029] Step 3: Preparation of the perovskite precursor solution containing additives: CH3NH3I and PbI2 were dissolved in a mixed solvent of DMF and DMSO (volume ratio 9:1) at a molar ratio of 1:1 to prepare a CH3NH3PbI3 precursor solution with a concentration of 1.4 mmol / mL. Then, 1-butyl-3-methylimidazolium trifluoroacetate additive with a concentration of 0.2 mmol / mL was added to the precursor solution and stirred until homogeneous.
[0030] Step 4, preparation of the perovskite absorbing layer: The precursor solution prepared in Step 3 is dropped onto the substrate prepared in Step 2 and spin-coated at 3000 rpm / min for 30 s. At the 10th second after spin-coating begins, 100 μL of chlorobenzene is rapidly added as an antisolvent. After spin-coating, the film is annealed on a 100 ℃ hot plate for 10 min. After cooling, the perovskite absorbing layer modified with 1-butyl-3-methylimidazolium trifluoroacetate is obtained.
[0031] Step 5, carbon electrode preparation: Commercial carbon paste is printed onto the perovskite light-absorbing layer obtained in step 4 by screen printing, and then heated at 110 °C for 5 min to solidify the carbon electrode, thus preparing the CH3NH3PbI3 perovskite solar cell modified with ionic liquid.
[0032] Example 2:
[0033] As described in Example 1, after the perovskite light-absorbing layer is prepared, a Spiro-OMeTAD hole transport layer is deposited by spin coating instead of a carbon electrode. The specific steps are as follows: Spiro-OMeTAD solution (72.3 mg / mL chlorobenzene solution, with 17.5 μL of 520 mg / mL LiTFSI acetonitrile solution and 28.8 μL of 4-TBP as an additive) is spin-coated onto a CH3NH3PbI3 perovskite film modified with 1-butyl-3-methylimidazolium trifluoroacetate at 4000 rpm / min for 30 s. Subsequently, the sample is placed in a vacuum evaporator, and a 100 nm thick gold electrode is deposited on the hole transport layer by thermal evaporation, thus preparing the ionic liquid-modified CH3NH3PbI3 perovskite solar cell.
[0034] Example 3:
[0035] First, ozone-treated ITO conductive glass was used as a substrate. A chlorobenzene solution (2 mg / mL, spin-coating speed 4000 rpm / min, 30 s) of PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), a hole transport layer material, was spin-coated onto the ITO and annealed at 150 °C for 15 min. Then, following the steps in Example 1, a CH3NH3PbI3 precursor solution containing 2.0 mmol / mL of 1-butyl-3-methylimidazolium trifluoroacetate additive was prepared, and a 1-butyl-3-methylimidazolium trifluoroacetate modified perovskite light-absorbing layer was spin-coated onto the PTAA layer using an anti-solvent method and annealed at 130 °C for 10 min. Subsequently, a chlorobenzene solution of PCBM ([6,6]-phenyl-C61-butyrate methyl ester) (20 mg / mL, spin coating speed 2000 rpm / min, 40 s) was spin-coated onto the perovskite layer as an electron transport layer, and annealed at 70 °C for 5 min. After cooling, an isopropanol solution of BCP (bath copper spirit) (0.5 mg / mL, spin coating speed 4000 rpm / min, 30 s) was further spin-coated onto the PCBM layer without annealing, serving as a cathode interface modification layer. Finally, a 100 nm silver electrode was deposited on the electron transport layer by thermal evaporation, thus preparing the ionic liquid-modified CH3NH3PbI3 inverted perovskite solar cell.
[0036] Example 4:
[0037] As described in Example 1, replacing 1-butyl-3-methylimidazolium trifluoroacetate with 1-ethyl-3-methylimidazolium diethyl phosphate can also yield a highly efficient CH3NH3PbI3 perovskite battery modified with ionic liquid.
[0038] Example 5:
[0039] As described in Example 1, replacing 1-butyl-3-methylimidazolium trifluoroacetate with 1-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imine can also yield a highly efficient CH3NH3PbI3 perovskite battery modified with ionic liquid.
[0040] The above content provides a detailed description of the present invention. Any similar implementations made without departing from the method of the present invention should fall within the protection scope of the present invention.
Claims
1. A method for passivating and modifying perovskite solar cells, characterized in that, This method uses ionic liquids as additives to perform dual passivation modification of the perovskite light-absorbing layer, involving both bulk and interfacial processes. The specific passivation steps are as follows: Step 1: Under a protective atmosphere, add the ionic liquid to the perovskite precursor solution, stir to dissolve, and filter after it is evenly mixed to obtain a perovskite solution containing additives. Step 2: Under a protective atmosphere, the perovskite solution obtained in Step 1 is coated onto the substrate to obtain a perovskite wet film. Step 3: Under a protective atmosphere, the perovskite wet film prepared in Step 2 is heated and annealed, and then naturally cooled to room temperature to obtain the perovskite light-absorbing layer of the perovskite solar cell passivated by ionic liquid.
2. The method according to claim 1, characterized in that, The ionic liquids include, but are not limited to, 1-butyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium diethyl phosphate, and 1-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.
3. The method according to claim 1, characterized in that, In step 1, the perovskite is CH3NH3PbI3, and its precursor solution is prepared by dissolving CH3NH3I and PbI2 in an organic solvent at a molar ratio of 1:1, with a solution concentration of 1.0 mmol / mL to 1.8 mmol / mL.
4. The method according to claim 3, characterized in that, The organic solvents include, but are not limited to, one or more of N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, and N-methylpyrrolidone.
5. The method according to claim 1, characterized in that, In step 1, the concentration of the ionic liquid added to the perovskite precursor solution is 0.1-1 mmol / mL.
6. The method according to claim 1, characterized in that, In step 2, the substrate is a conductive glass with an electron transport layer deposited on it; the electron transport layer is TiO2, SnO2, ZnO or WO3; the conductive glass is FTO conductive glass or ITO conductive glass.
7. The method according to claim 1, characterized in that, In step 2, the perovskite solution is coated by spin-coating the perovskite solution onto the substrate, with an anti-solvent added during the spin-coating process.
8. The method according to claim 8, characterized in that, The antisolvents include, but are not limited to, chlorobenzene, toluene, diethyl ether, methyl formate, methyl acetate, ethyl acetate, etc.; the spin coating of the perovskite solution is completed in one step; the spin coating rate is 3000~5000 rpm / min, and the spin coating time is 20~30 s.
9. The method according to claim 1, characterized in that, In step 3, the annealing temperature is 100~130℃ and the annealing time is 10~25 min.
10. The method according to claim 1, characterized in that, Steps 1 to 3 are all performed under a protective atmosphere; the atmosphere includes one or more of the following: air, nitrogen, argon, helium, neon, and carbon dioxide, with a relative humidity below 50%.
11. A perovskite light-absorbing layer for an ion liquid passivated and modified perovskite solar cell prepared by the method of any one of claims 1-10.
12. The ion liquid passivated modified perovskite light-absorbing layer according to claim 11, characterized in that, The perovskite light-absorbing layer is a polycrystalline thin film.
13. The ion liquid passivated modified perovskite light-absorbing layer according to claim 12, characterized in that, The anions in the ionic liquid can interact with uncoordinated Pb²⁺ ions in the perovskite, and the cations in the ionic liquid can induce the formation of PbI₂ grains, which are distributed on the surface and grain boundaries of the perovskite.