A step towards RoHS compliance for perovskite devices by using a novel lead-capturing encapsulant

Despite the significant progress made in perovskite solar cells, device degradation under ambient conditions and the potentially hazardous release of toxic lead into the environment is a major concern. Packaging and encapsulation of solar cells and modules will address these issues to an extent. However, during leaching mobile lead ions can diffuse through most commercially used edge seal adhesives, making even standard encapsulation systems not appropriate for packaging perovskite solar cells. In this work, an ionomer of polyethylene co-methacrylic acid polymer film (Surlyn) modified with functional groups that interact with mobile lead ions is used to encapsulate perovskite films. The functionalization of the encapsulant was tailored by modifying the matrix polymer with Zeolitic imidazolium framework- 67 (ZIF-67) through polydopamine as the anchoring platform. This modified encapsulant exhibited a reduced lead leaching by more than ∼8 orders. The design of experiments was carried out to evaluate the modified encapsulant efficacy in preventing lead leaching through it. In addition, new experimental techniques were designed for understanding the characteristics and reliability for an extended period.