Minimizing Ionic Losses in DMSO-Free Tin-Based Perovskite Solar Cells

Despite the exceptional optoelectronic properties of Pb-based perovskite solar cells, the concerns about their intrinsic instability due to the presence of mobile ions and their potential toxicity are two major obstacles for commercialization. Sn-based perovskites have been revealed as ecofriendly perovskite counterparts. Furthermore, they are believed to exhibit smaller ion-induced instabilities, although thorough investigations are missing. Herein, we investigate the nature of mobile species, quantify the ionic loss within Sn-based perovskite solar cells, and compare with those of Pb-based and mixed PbSn devices. We report over 10-fold lower ion densities with minimal ionic losses in DMSO-free processed Sn samples compared with Pb-based perovskites. The pure Sn-based samples also show the lowest associated ionic losses with sustained device and film stability during prolonged illumination. This study thus propels our understanding of ion migration phenomena in Sn-based devices and paves the way for the development of innovative, stable thin film solar cells with suppressed ion migration.