Localized transport channels through nanoscale phase separation for efficient inverted perovskite solar cells

Interfacial recombination at the perovskite/PCBM interface is a critical factor for efficiency loss in inverted perovskite solar cells (PSCs). Different from the commonly used fully covered PCBM transport layer, we developed a localized electron transport channel to reduce the perovskite/PCBM direct contact area by introducing nanoscale separated PM6:PCBM. In this structure, electrons cannot be transported throughout PM6. However, these electrons can effectively circumvent PM6 and be extracted by PCBM due to the bi-continuous and nanoscale phase separation in PM6:PCBM, which will effectively reduce the contact area between perovskite and PCBM, thus inhibiting interfacial recombination. The resulting PSCs exhibited a high efficiency of 25.60% with good stability, retaining 93.1% of the initial efficiency after 65 °C aging for 2000 h.