Metal Halide Perovskite Surfaces with Mixed A‐Site Cations: Atomic Structure and Device Stability

This is the authors' abstract. We don't add key points for this paper.

Mixing cations in the perovskite structure has been shown to improve optoelectronic device performance and stability. In particular, Cs x MA 1‐x PbBr 3 (MA = CH 3 NH 3 ) has been used to build high‐efficiency light‐emitting diodes. Despite those advantages, little is known about the exact location of the cations in the mixed perovskite film, and how cation distribution affects device properties and stability. By using scanning tunneling microscopy , the exact atomic structure of the mixed cation Cs x MA 1‐x PbBr 3 perovskite interface is revealed. In addition, X‐ray photoelectron spectroscopy, ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy are used to study the stability and electronic properties of the Cs x MA 1‐x PbBr 3 perovskite film. Partial substitution of MA + by Cs + induces a modification of the perovskite surface structure, leading to improved device stability is shown. These results provide a better understanding of the key parameters involved in the stability of mixed cation perovskite solar cells.