Malgorzata Kot (Sowinska)

Interfaces between hybrid perovskite absorber and its adjacent charge‐transporting layers are of high importance for solar cells performance. Understanding their chemical and electronic properties is a key step in designing efficient and stable perovskite solar cells. In this work, the tapered cross‐section photoemission spectroscopy (TCS‐PES) method is used to study the methylammonium lead iodide (CH 3 NH 3 PbI 3 ) (MAPI)‐based solar cells in two configurations, that is, in an inverted p –i–n and in a classical n–i–p architecture. It is revealed in the results that the MAPI film deposited once on the n‐type TiO 2 and once on the p ‐type NiO x substrates is neither an intrinsic semiconductor nor adapts to the dopant nature of the substrate underneath, but it is heavily n‐type doped on both substrates. In addition to that, the TCS‐PES results identify that the band bending between the MAPI film and the hole transporting layer (HTL) layer depends on the perovskite solar cells architecture. In particular, a band bending on the HTL side in the n–i–p and at the MAPI in the p –i–n architecture is found. The flat band of NiO x at the NiO x /MAPI interface can be explained by the Fermi level pinning of the NiO x at the interface.