Efficient Perovskite Solar Cells Based on Dual-Interface "Green" Lead Management

Perovskite solar cells (PSCs) offer strong potential for sustainable energy conversion, yet their reliance on toxic-lead (Pb) continues to restrict environmental compatibility and large-scale deployment. To address this challenge, a dual-interface Pb-management approach enabled by custom-designed chelating molecules is introduced. These tailored chelators are engineered with high Pb²⁺ affinity and controlled coordination geometry, allowing them to suppress Pb-related defect formation, promote vertical grain growth, and release residual lattice stress. When synergistically forming an internal encapsulation layer on both sides of the perovskite film with chitosan (CS), it supports efficient charge transport and enhances structural integrity. This configuration reduces Pb leakage to 0.86 ppm after 9 h immersion in pure water, which is below wastewater discharge limits, and efficiently mitigates Pb-induced biotoxicity. Adopting this strategy p-i-n devices maintain 96% of initial performance after 3000 h of exposure and reach a champion efficiency of 26.91% (third-party certified efficiency 26.60%). The unverified efficiency of n-i-p devices reached 25.60%. The strategy is applicable to both p-i-n and n-i-p device architectures and may be extendable to other Pb-based perovskite systems.