Environmental-Friendly Polymer for Efficient and Stable Inverted Perovskite Solar Cells with Mitigating Lead Leakage

Although perovskite solar cells (PSCs) are on the road to industrialization, the operational stability under high efficiency still needs to be improved, and the water solubility of lead ions (Pb²⁺) will cause environmental pollution problems. Herein, it is successfully implanted an environment-friendly (biodegradability) poly(butylene adipate-coterephthalate) polymer (PBAT) into the perovskite film, which can passivate the uncoordinated Pb²⁺ and neutral iodine defects of the perovskite material because of the adequate carbonyl groups and benzene rings in PBAT polymer, thereby regulating the crystallization of perovskite film with lower trap density, inhibiting the nonradiative recombination and improving charge carrier transport. As a result, the polymer-incorporated inverted PSCs achieve optimal conversion efficiencies of 22.07% (0.1 cm²) and 20.31% (1 cm²). Meanwhile, the incorporated device, after being encapsulated, exhibits a prominent improvement in operational stability of high-efficiency device under maximum power point tracking and continuous one sunlight illumination, maintaining the initial efficiency of 80% for 3249 h. More importantly, the polymer network can protect Pb²⁺ from being dissolved by water and prevent nearly 98% of Pb²⁺ from leaking by directly immersing the polymer-coated perovskite film in water. Environmental-friendly molecules provide new hope for solving lead poisoning and improving device operational stability under high efficiency.