Immobilizing Lead Ions via Supramolecular Sequestration Enables Efficient and Eco-Friendly Perovskite Solar Cells

Abstract

Solution processing renders perovskite solar cells low-cost and scalable, yet defect formation and lead-induced environmental toxicity hinder their practical application to date. Herein, we propose a synergistic strategy that mitigates the above issues. We introduce a ring-shaped supermolecule, containing functional groups that interact with lead ions in the perovskite lattice, into perovskite precursors. Particularly, we find that excessive unreacted PbI₂ is minimized due to the insertion of this molecule during two-step fabrication. Additionally, the multisite interaction between this molecule and perovskites renders defect passivation and improved film morphology. More importantly, the ring-shaped supramolecular structure immobilizes Pb ions in the perovskite lattice via host–guest sequestration, leading to substantially reduced ion leakage of the device in an aqueous immersion test. Eventually, this process yielded an inverted device with a high power conversion efficiency (25.13%) and excellent stability (>90% retention after 1000 h of continuous illumination). Such results reflect the successful multifunctionality of our supermolecule and shed light on strategies for designing efficient additives toward environmentally friendly perovskite solar cells.