The impact of spiro-OMeTAD photodoping on the reversible light-induced transients of perovskite solar cells

Hole transporting materials (HTMs) play essential roles in facilitating hole extraction and suppressing recombination lead halide perovskite solar cells (PSCs). High levels of p-doping HTMs is necessary for achieving high device performance, attributed to an increased electrical conductivity. In this work, we provide evidences that the poor performance PSCs with low doping (i.e., 4 mol% spiro-OMeTAD+) spiro-OMeTAD mainly caused by presence a Schottky barrier at perovskite/spiro-OMeTAD interface, hampering injection. Under continuous illumination open-circuit condition, gradually diminishes, increasing PSC power conversion efficiency 70-fold after 7 h. This process completely reversible, returning initial dark storage. We attribute improvement gradual photodoping spiro-OMeTAD, triggered transfer photogenerated holes mediated slow migration anions from compensate newly formed spiro-OMeTAD+. In-situ parallel analyses impedance spectroscopy (IS) photoluminescence are employed gain insights into charge dynamics along light soaking. find resistance overlays signal frequency arc IS, having important implications IS data analysis PSCs. The work elucidates major mechanism causing variations during light/dark cycling, commonly observed PSCs, which complicates determination long-term stability.