Water repellent room temperature vulcanized silicone for enhancing the long-term stability of perovskite solar cells

[Display omitted] •A new structure is explained for enhancing the stability of perovskite solar cells.•More than 80% retention at harsh conditions is obtained for encapsulated solar cells.•The proposed encapsulating layer is feasible to apply for commercial applications.•The encapsulated layer has no needs for common post heat-treatments or UV curing. A key direction toward enhancing the long term and outdoor stability of the perovskite solar cells is encapsulation. As a result, a suitable encapsulation package is required to prevent moisture and oxygen penetration toward the perovskite solar cells. In this work, a low-cost commercially available bilayer structure of poly (methyl methacrylate)/ room-temperature vulcanizing silicone rubber (RTV) encapsulation package for enhancing the long term stability of the perovskite solar cells has been investigated. Encapsulated cells retained more than 80% of the initial efficiency at the environmental condition of 50% moisture, and room temperature after 1000 h, however reference cell efficiency decrease severely. The origin of enhanced stability in encapsulated cells under harsh environmental condition was investigated and explained by electrochemical impedance spectroscopy measurements. Our study, in general, introduces a novel encapsulating layer which is feasible to apply without any needs for further common post heat-treatments or UV curing.