LiF in Inverted Perovskite Solar Cells: Dipole or Doping?

The functions and mechanisms of thermally evaporated lithium fluoride, widely acknowledged for its role in passivating the perovskite surface as a dipole interlayer, remain not fully elucidated. This work reveals the beneficial effects of LiF originating from interstitial incorporation of lithium cations in the underlying perovskite layer.