Cascade Bridge Interfacial Design for Stable and Sustainable Flexible Perovskite Solar Cells

Abstract

Constructing an interlayer between perovskite and zinc oxide (ZnO) electron transporting layer to passivate the implacable interfacial defects for upgrading the efficiency and stability of flexible perovskite solar cells (f-PSC) is a daunting challenge and remains under explored. Herein, we present a cascade bridge interlayer strategy of zeolitic imidazole framework-8 (ZIF-8) at the ZnO/perovskite interface. The ZIF-8 interlayer uplifts the work function, creating a cascade pathway and bridges through nitrogen bonding with Pb²⁺ ions of perovskite, thereby facilitating electron transport and reducing interfacial charge recombination. Consequently, the ZnO surface defects are passivated by alleviating the OH^‒ species, and thus the device stability is significantly improved. The f-PSC with ZIF-8 interlayer delivers a stable conversion efficiency of 17.10% with minimal hysteresis. By utilizing the piezo-phototronic effect and subjecting the f-PSC to a tensile strain of 1.6%, a stable efficiency of 18.47% was achieved, representing one of the highest reported efficiencies for ZnO nanorods-based f-PSC. Furthermore, the ZnO‒ZIF-8 exhibits high adsorption capacity toward lead and traps the mobile Pb²⁺ ions at the ZnO/perovskite interface, preventing the negative impact of lead leaching on environmental sustainability.

Keywords

cascade bridge interlayer / lead-leakage control / piezo-phototronic effect / zeolitic imidazole framework-8 / zinc oxide

References

[1] J. Park, J. Kim, H.-S. Yun, et al., “Controlled Growth of Perovskite Layers With Volatile Alkylammonium Chlorides,” Nature 616, no. 7958 (2023): 724-730.

[2] C. Liu, Y. Yang, H. Chen, et al., “Bimolecularly Passivated Interface Enables Efficient and Stable Inverted Perovskite Solar Cells,” Science 382, no. 6672 (2023): 810-815.

[3] M. Pitaro, E. K. Tekelenburg, S. Shao, and M. A. Loi, “Tin Halide Perovskites: From Fundamental Properties to Solar Cells,” Advanced Materials 34, no. 1 (2022): 2105844.

[4] S. Seong, Y. Liu, and X. Gong, “Mechanical Study of Perovskite Solar Cells: Opportunities and Challenges for Wearable Power Source,” Optical Materials Express 12, no. 2 (2022): 772-787.

[5] Y.-Y. Zhang, S. Chen, P. Xu, et al., “Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor CH₃NH₃PbI₃,” Chinese Physics Letters 35, no. 3 (2018): 036104.

[6] Y. Cheng and L. Ding, “Perovskite/Si Tandem Solar Cells: Fundamentals, Advances, Challenges, and Novel Applications,” SusMat 1, no. 3 (2021): 324-344.

[7] J. Zayed and S. Philippe, “Acute Oral and Inhalation Toxicities in Rats With Cadmium Telluride,” International Journal of Toxicology 28, no. 4 (2009): 259-265.

[8] H. Zhang, J.-W. Lee, G. Nasti, et al., “Lead Immobilization for Environmentally Sustainable Perovskite Solar Cells,” Nature 617, no. 7962 (2023): 687-695.

[9] G. Fu, D.-K. Lee, C. Ma, and N.-G. Park, “Disulfidation Interfacial Engineering Toward Stable, Lead-Immobilizable Perovskite Solar Cells,” ACS Energy Letters 8, no. 11 (2023): 4563-4571.

[10] Y. Jiang, L. Qiu, E. J. Juarez-Perez, et al., “Reduction of Lead Leakage From Damaged Lead Halide Perovskite Solar Modules Using Self-Healing Polymer-Based Encapsulation,” Nature Energy 4, no. 7 (2019): 585-593.

[11] Z. Li, X. Wu, S. Wu, et al., “An Effective and Economical Encapsulation Method for Trapping Lead Leakage in Rigid and Flexible Perovskite Photovoltaics,” Nano Energy 93 (2022): 106853.

[12] M. Yang, T. Tian, Y. Fang, et al., “Reducing Lead Toxicity of Perovskite Solar Cells With a Built-In Supramolecular Complex,” Nature Sustainability 6, no. 11 (2023): 1455-1464.

[13] Z. Li, C. Jia, Z. Wan, et al., “Hyperbranched Polymer Functionalized Flexible Perovskite Solar Cells With Mechanical Robustness and Reduced Lead Leakage,” Nature Communications 14, no. 1 (2023): 6451.

[14] H. Furukawa, K. E. Cordova, M. O'Keeffe, and O. M. Yaghi, “The Chemistry and Applications of Metal‒Organic Frameworks,” Science 341, no. 6149 (2013): 1230444.

[15] P. A. Kobielska, A. J. Howarth, O. K. Farha, and S. Nayak, “Metal‒organic Frameworks for Heavy Metal Removal From Water,” Coordination Chemistry Reviews 358 (2018): 92-107.

[16] X. Liang, X. Zhou, C. Ge, et al., “Advance and Prospect of Metal‒Organic Frameworks for Perovskite Photovoltaic Devices,” Organic Electronics 106 (2022): 106546.

[17] Y. Ye, Y. Yin, Y. Chen, S. Li, L. Li, and Y. Yamauchi, “Metal‒Organic Framework Materials in Perovskite Solar Cells: Recent Advancements and Perspectives,” Small 19, no. 25 (2023): 2208119.

[18] J. Dou, C. Zhu, H. Wang, et al., “Synergistic Effects of Eu-MOF on Perovskite Solar Cells With Improved Stability,” Advanced Materials 33, no. 39 (2021): 2102947.

[19] U. Ryu, S. Jee, J.-S. Park, et al., “Nanocrystalline Titanium Metal‒Organic Frameworks for Highly Efficient and Flexible Perovskite Solar Cells,” ACS Nano 12, no. 5 (2018): 4968-4975.

[20] S. Wu, Z. Li, M.-Q. Li, et al., “2D Metal‒Organic Framework for Stable Perovskite Solar Cells With Minimized Lead Leakage,” Nature Nanotechnology 15, no. 11 (2020): 934-940.

[21] J. Cao, C.-K. Liu, V. Piradi, et al., “Ultrathin Self-Assembly Two-Dimensional Metal‒Organic Framework Films as Hole Transport Layers in Ideal-Bandgap Perovskite Solar Cells,” ACS Energy Letters 7, no. 10 (2022): 3362-3369.

[22] M. Shen, Y. Zhang, H. Xu, and H. Ma, “MOFs Based on the Application and Challenges of Perovskite Solar Cells,” Iscience 24, no. 9 (2021): 103069.

[23] M. Li, D. Xia, Y. Yang, et al., “Doping of [In₂(phen)₃Cl₆]·CH₃CN·2H₂O Indium-Based Metal‒Organic Framework Into Hole Transport Layer for Enhancing Perovskite Solar Cell Efficiencies,” Advanced Energy Materials 8, no. 10 (2018): 1702052.

[24] C.-K. Liu, K.-H. Wu, Y.-A. Lu, et al., “Introducing Postmetalation Metal‒Organic Framework to Control Perovskite Crystal Growth for Efficient Perovskite Solar Cells,” ACS Applied Materials & Interfaces 13, no. 50 (2021): 60125-60134.

[25] Z. Qin, Y. Chen, X. Wang, et al., “Zwitterion-Functionalized SnO₂ Substrate Induced Sequential Deposition of Black-Phase FAPbI₃ With Rearranged PbI₂ Residue,” Advanced Materials 34, no. 32 (2022): 2203143.

[26] N. K. Noel, S. N. Habisreutinger, B. Wenger, et al., “Elucidating the Role of a Tetrafluoroborate-Based Ionic Liquid at the n-Type Oxide/Perovskite Interface,” Advanced Energy Materials 10, no. 4 (2020): 1903231.

[27] S. Yang, S. Chen, E. Mosconi, et al., “Stabilizing Halide Perovskite Surfaces for Solar Cell Operation With Wide-Bandgap Lead Oxysalts,” Science 365, no. 6452 (2019): 473-478.

[28] Q. Jiang, Y. Zhao, X. Zhang, et al., “Surface Passivation of Perovskite Film for Efficient Solar Cells,” Nature Photonics 13, no. 7 (2019): 460-466.

[29] H. Wang, C. Guo, F. Li, et al., “Push‒Pull Substituent Design of Fullerene Dimer at the Buried Interface Toward Stable and Efficient Perovskite Solar Cells,” Science China Materials 67, no. 1 (2024): 58-66.

[30] H. Wang, F. Li, P. Wang, et al., “Chlorinated Fullerene Dimers for Interfacial Engineering Toward Stable Planar Perovskite Solar Cells With 22.3% Efficiency,” Advanced Energy Materials 10, no. 21 (2020): 2000615.

[31] M.-R. Ahmadian-Yazdi, N. Gholampour, and M. Eslamian, “Interface Engineering by Employing Zeolitic Imidazolate Framework-8 (ZIF-8) as the Only Scaffold in the Architecture of Perovskite Solar Cells,” ACS Applied Energy Materials 3, no. 4 (2020): 3134-3143.

[32] Z. Jin, B. Li, Y. Xu, et al., “Confinement of MACl Guest in 2D ZIF-8 Triggers Interface and Bulk Passivation for Efficient and UV-Stable Perovskite Solar Cells,” Journal of Materials Chemistry C 11, no. 20 (2023): 6730-6740.

[33] W. Sheng, J. He, J. Yang, et al., “Multifunctional Metal‒Organic Frameworks Capsules Modulate Reactivity of Lead Iodide Toward Efficient Perovskite Solar Cells With UV Resistance,” Advanced Materials 35, no. 33 (2023): 2301852.

[34] C. Qiu, Y. Wu, J. Song, W. Wang, and Z. Li, “Efficient Planar Perovskite Solar Cells With ZnO Electron Transport Layer,” Coatings 12, no. 12 (2022): 1981.

[35] W.-W. Zhan, Q. Kuang, J.-Z. Zhou, X.-J. Kong, Z.-X. Xie, and L.-S. Zheng, “Semiconductor@Metal‒Organic Framework Core‒Shell Heterostructures: A Case of ZnO@ZIF-8 Nanorods With Selective Photoelectrochemical Response,” Journal of the American Chemical Society 135, no. 5 (2013): 1926-1933.

[36] J. Yang, B. D. Siempelkamp, E. Mosconi, F. De Angelis, and T. L. Kelly, “Origin of the Thermal Instability in CH₃NH₃PbI₃ Thin Films Deposited on ZnO,” Chemistry of Materials 27, no. 12 (2015): 4229-4236.

[37] Y. Cheng, Q.-D. Yang, J. Xiao, et al., “Decomposition of Organometal Halide Perovskite Films on Zinc Oxide Nanoparticles,” ACS Applied Materials & Interfaces 7, no. 36 (2015): 19986-19993.

[38] G. S. Han, H. W. Shim, S. Lee, M. L. Duff, and J. K. Lee, “Low-Temperature Modification of ZnO Nanoparticles Film for Electron-Transport Layers in Perovskite Solar Cells,” Chemsuschem 10, no. 11 (2017): 2425-2430.

[39] J. Cao, B. Wu, R. Chen, et al., “Efficient, Hysteresis-Free, and Stable Perovskite Solar Cells With ZnO as Electron-Transport Layer: Effect of Surface Passivation,” Advanced Materials 30, no. 11 (2018): 1705596.

[40] A. Soultati, A. Fakharuddin, E. Polydorou, et al., “Lithium Doping of ZnO for High Efficiency and Stability Fullerene and Non-Fullerene Organic Solar Cells,” ACS Applied Energy Materials 2, no. 3 (2019): 1663-1675.

[41] J. Zhang, C. H. Tan, T. Du, et al., “ZnO‒PCBM Bilayers as Electron Transport Layers in Low-Temperature Processed Perovskite Solar Cells,” Science Bulletin 63, no. 6 (2018): 343-348.

[42] X. Zhao, H. Shen, Y. Zhang, et al., “Aluminum-Doped Zinc Oxide as Highly Stable Electron Collection Layer for Perovskite Solar Cells,” ACS Applied Materials & Interfaces 8, no. 12 (2016): 7826-7833.

[43] G. Liu, Y. Zhong, H. Mao, et al., “Highly Efficient and Stable ZnO-Based MA-Free Perovskite Solar Cells via Overcoming Interfacial Mismatch and Deprotonation Reaction,” Chemical Engineering Journal 431 (2022): 134235.

[44] R. Chen, J. Cao, Y. Duan, et al., “High-Efficiency, Hysteresis-Less, UV-Stable Perovskite Solar Cells With Cascade ZnO‒ZnS Electron Transport Layer,” Journal of the American Chemical Society 141, no. 1 (2018): 541-547.

[45] J. W. Lim, H. Wang, C. H. Choi, et al., “Polyethylenimine Ethoxylated Interlayer-Mediated ZnO Interfacial Engineering for High-Performance and Low-Temperature Processed Flexible Perovskite Solar Cells: A Simple and Viable Route for One-Step Processed CH₃NH₃PbI₃,” Journal of Power Sources 438 (2019): 226956.

[46] M. Fahim, I. Firdous, W. Zhang, and W. A. Daoud, “Bifunctional Interfacial Engineering for Piezo-Phototronic Enhanced Photovoltaic Performance of Wearable Perovskite Solar Cells,” Nano Energy 86 (2021): 106127.

[47] X. C. Huang, Y. Y. Lin, J. P. Zhang, and X. M. Chen, “Ligand-Directed Strategy for Zeolite-Type Metal‒Organic Frameworks: Zinc (II) Imidazolates With Unusual Zeolitic Topologies,” Angewandte Chemie International Edition 45, no. 10 (2006): 1557-1559.

[48] S.-H. Yi, S.-K. Choi, J.-M. Jang, J.-A. Kim, and W.-G. Jung, “Low-Temperature Growth of ZnO Nanorods by Chemical Bath Deposition,” Journal of Colloid and Interface Science 313, no. 2 (2007): 705-710.

[49] K. Yao, S. Leng, Z. Liu, et al., “Fullerene-Anchored Core‒Shell ZnO Nanoparticles for Efficient and Stable Dual-Sensitized Perovskite Solar Cells,” Joule 3, no. 2 (2019): 417-431.

[50] S. Feng, X. Jia, J. Yang, Y. Li, S. Wang, and H. Song, “One-Pot Synthesis of Core‒Shell ZIF-8@ ZnO Porous Nanospheres With Improved Ethanol Gas Sensing,” Journal of Materials Science: Materials in Electronics 31 (2020): 22534-22545.

[51] J. Park, J.-B. Ju, W. Choi, and S.-O. Kim, “Highly Reversible ZnO@ ZIF-8-Derived Nitrogen-Doped Carbon in the Presence of Fluoroethylene Carbonate for High-Performance Lithium-Ion Battery Anode,” Journal of Alloys and Compounds 773 (2019): 960-969.

[52] Y. Dkhissi, S. Meyer, D. Chen, et al., “Stability Comparison of Perovskite Solar Cells Based on Zinc Oxide and Titania on Polymer Substrates,” Chemsuschem 9, no. 7 (2016): 687-695.

[53] K. Schutt, P. K. Nayak, A. J. Ramadan, B. Wenger, Y. H. Lin, and H. J. Snaith, “Overcoming Zinc Oxide Interface Instability With a Methylammonium-Free Perovskite for High-Performance Solar Cells,” Advanced Functional Materials 29, no. 47 (2019): 1900466.

[54] J. Liu, Y. Chen, Y. Hu, et al., “A Novel Metal‒Organic Framework-Derived ZnO@ZIF-8 Adsorbent With High Efficiency for Pb(II) From Solution: Performance and Mechanisms,” Journal of Molecular Liquids 356 (2022): 119057.

[55] S. Leontiev, S. Koshcheev, V. Devyatov, A. Cherkashin, and É. P. Mikheeva, “Detailed XPS and UPS Studies of the Band Structure of Zinc Oxide,” Journal of Structural Chemistry 38, no. 5 (1997): 725-731.

[56] S. Park, W. Jang, and D. H. Wang, “Alignment of Cascaded Band-Gap via PCBM/ZnO Hybrid Interlayers for Efficient Perovskite Photovoltaic Cells,” Macromolecular Research 26, no. 5 (2018): 472-476.

[57] J. Bisquert, I. Mora-Sero, and F. Fabregat-Santiago, “Diffusion-Recombination Impedance Model for Solar Cells With Disorder and Nonlinear Recombination,” ChemElectroChem 1, no. 1 (2014): 289-296.

[58] E. J. Juarez-Perez, M. Wuβler, F. Fabregat-Santiago, et al., “Role of the Selective Contacts in the Performance of Lead Halide Perovskite Solar Cells,” The Journal of Physical Chemistry Letters 5, no. 4 (2014): 680-685.

[59] N. Chai, X. Chen, Z. Zeng, et al., “Photoexcitation-Induced Passivation of SnO₂ Thin Film for Efficient Perovskite Solar Cells,” National Science Review 10, no. 11 (2023).

[60] Q. Dong, C. Zhu, M. Chen, et al., “Interpenetrating Interfaces for Efficient Perovskite Solar Cells With High Operational Stability and Mechanical Robustness,” Nature Communications 12, no. 1 (2021): 973.

[61] J. Sun, Q. Hua, R. Zhou, et al., “Piezo-Phototronic Effect Enhanced Efficient Flexible Perovskite Solar Cells,” ACS Nano 13, no. 4 (2019): 4507-4513.

[62] X. Wen, W. Wu, and Z. L. Wang, “Effective Piezo-Phototronic Enhancement of Solar Cell Performance by Tuning Material Properties,” Nano Energy 2, no. 6 (2013): 1093-1100.

[63] B. Sharma and R. Purohit, Semiconductor Heterojunctions, Vol 5. (Elsevier, 2015).

[64] K. T. Butler, C. H. Hendon, and A. Walsh, “Designing Porous Electronic Thin-Film Devices: Band Offsets and Heteroepitaxy,” Faraday Discussions 201 (2017): 207-219.

[65] E. J. Juarez-Perez and M. Haro, “Perovskite Solar Cells Take a Step Forward,” Science 368, no. 6497 (2020): 1309.

[66] L. Shi, M. P. Bucknall, T. L. Young, et al., “Gas Chromatography‒Mass Spectrometry Analyses of Encapsulated Stable Perovskite Solar Cells,” Science 368, no. 6497 (2020): eaba2412.

[67] M.-W. Liu, G. Liu, Y.-F. Wang, B.-X. Lei, and W.-Q. Wu, “Applications of Multifunctional Metal‒Organic Frameworks in Perovskite Photovoltaics: Roles, Advantages and Prospects,” Materials Chemistry Frontiers 8, no. 4 (2024): 869-879.

[68] S. N. Raja, Y. Bekenstein, M. A. Koc, et al., “Encapsulation of Perovskite Nanocrystals Into Macroscale Polymer Matrices: Enhanced Stability and Polarization,” ACS Applied Materials & Interfaces 8, no. 51 (2016): 35523-35533.

[69] J. Wu, Y. Cui, B. Yu, et al., “A Simple Way to Simultaneously Release the Interface Stress and Realize the Inner Encapsulation for Highly Efficient and Stable Perovskite Solar Cells,” Advanced Functional Materials 29, no. 49 (2019): 1905336.

[70] Y. Zhang, Y. Han, Y. Xu, et al., “Enhancing Efficiency and Stability of Perovskite Solar Cells via in Situ Incorporation of Lead Sulfide Layer,” Sustainable Energy & Fuels 5, no. 14 (2021): 3700-3704.

[71] J. Wang, R. Zhang, H. Xu, Y. Chen, H. Zhang, and N.-G. Park, “Polyacrylic Acid Grafted Carbon Nanotubes for Immobilization of Lead (II) in Perovskite Solar Cell,” ACS Energy Letters 7, no. 5 (2022): 1577-1585.

[72] S. Chen, Y. Deng, X. Xiao, S. Xu, P. N. Rudd, and J. Huang, “Preventing Lead Leakage With Built-In Resin Layers for Sustainable Perovskite Solar Cells,” Nature Sustainability 4, no. 7 (2021): 636-643.

[73] X. Wei, M. Xiao, B. Wang, et al., “Avoiding Structural Collapse to Reduce Lead Leakage in Perovskite Photovoltaics,” Angewandte Chemie International Edition 61, no. 27 (2022): e202204314.

[74] B. Niu, H. Wu, J. Yin, et al., “Mitigating the Lead Leakage of High-performance Perovskite Solar Cells via In Situ Polymerized Networks,” ACS Energy Letters 6, no. 10 (2021): 3443-3449.

[75] Y. Liu, T. Chen, Z. Jin, et al., “Tough, Stable and Self-Healing Luminescent Perovskite‒Polymer Matrix Applicable to all Harsh Aquatic Environments,” Nature Communications 13, no. 1 (2022): 1338.

[76] X. Li, F. Zhang, H. He, J. J. Berry, K. Zhu, and T. Xu, “On-Device Lead Sequestration for Perovskite Solar Cells,” Nature 578, no. 7796 (2020): 555-558.

[77] X. Xiao, M. Wang, S. Chen, et al., “Lead-Adsorbing Ionogel-Based Encapsulation for Impact-Resistant, Stable, and Lead-Safe Perovskite Modules,” Science Advances 7, no. 44 (2021): eabi8249.

[78] Z. Li, X. Wu, B. Li, et al., “Sulfonated Graphene Aerogels Enable Safe-to-Use Flexible Perovskite Solar Modules,” Advanced Energy Materials 12, no. 5 (2022): 2103236.

[79] L. R. D. Mendez, B. N. Breen, and D. Cahen, “Lead Sequestration From Halide Perovskite Solar Cells With a Low-Cost Thiol-Containing Encapsulant,” ACS Applied Materials & Interfaces 14, no. 26 (2022): 29766-29772.

[80] H. Luo, P. Li, J. Ma, L. Han, Y. Zhang, and Y. Song, “Sustainable Pb Management in Perovskite Solar Cells Toward Eco-Friendly Development,” Advanced Energy Materials 12, no. 30 (2022): 2201242.

[81] K. Ahmad, H.-u.-R. Shah, M. Ashfaq, et al., “Effect of Metal Atom in Zeolitic Imidazolate Frameworks (ZIF-8 & 67) for Removal of Pb²⁺ & Hg²⁺ From Water,” Food and Chemical Toxicology 149 (2021): 112008.

RIGHTS & PERMISSIONS

2025 The Author(s). SusMat published by Sichuan University and John Wiley & Sons Australia, Ltd.