Blocking Ion Migration with Spiro Compounds for Stable Perovskite Solar Cells

Perovskite solar cells (PSCs) have experienced impressive development toward commercialization in the past few years. However, the intrinsic hydrophilic nature of perovskites and the severe ion migration within the device prevent additional enhancement of the long-term stability of PSCs. Here we develop two Spiro-structured molecules, S1 and S2, as interlayers in n-i-p PSCs, effectively blocking ion migration between the Spiro-OMeTAD and perovskite layers. The S2-based PSCs show excellent long-term stability, remaining 95% of its initial efficiency after storage in ambient (around 40% humidity) for more than 3980 h, considerably more stable than the pristine PSCs.