Vitrification Transformation of Poly(Ethylene Oxide) Activating Interface Passivation for High‐Efficiency Perovskite Solar Cells

Interface engineering is critical for achieving high‐efficiency and high‐stability perovskite solar cells (PSCs). Herein, a new interface engineering approach—poly(ethylene oxide) (PEO) modification of SnO 2 quantum dot (QD) film—to improve electron transport is introduced. It is found that when the PEO film is annealed over its glass‐transition temperature, the ether‐oxygen unshared electron pair in the PEO film activates to form a crosslinking complex with metal ions at the SnO 2 QD and perovskite interface, which triggers heterogeneous nucleation over the perovskite precursor film and is beneficial for achieving uniform and dense perovskite films. PEO is also shown to passivate the bulk defects of perovskite films and the interface defects between SnO 2 QD and perovskite, which promotes electron‐transferring from the perovskite layer to cathode. PSCs based on SnO 2 QD with PEO treatment exhibit an enhanced efficiency, leading to a champion PCE of 20.23%, with good reproducibility and stability.