Bioinspired liquid-repelling sealing films for flexible perovskite solar cells

Abstract

Flexible perovskite solar cells (PSCs) (FPSCs) have great potential to be applied in cheap and portable applications, thanks to their solution processability at low temperatures. It is essential to prevent the devices from exposure to various liquids, as well as oxygen and water vapors, that degrade their performance. A sealing layer with a liquid-repelling property can be realized through finely tuning its solid surface energy. However, few attempts have been reported for use with flexible PSCs because the film should also be compatible with the processing and mechanical flexibility of the device. In this study, we develop a polydimethylsiloxane (PDMS)-based sealing layer comprising superomniphobic microstructures inspired by cuticles of springtails. Sealed with this layer, flexible PSCs showed liquid-repelling ability against various liquids, including rainwater, seawater, and organic solvents. The photovoltaic performance was maintained even after exposure to deionized water and gamma butyrolactone and after 10,000 repeated bending cycles with a bending radius of 4 mm, which indicates the excellent compatibility of the structures with flexible devices. As the first report on utilization for flexible PSCs, this work suggests that the springtail-inspired PDMS structures are a promising sealing technology for flexible outdoor optoelectronic applications.