TY - GEN A1 - Kot, Małgorzata A1 - Vorokhta, Mykhailo A1 - Wang, Zhiping A1 - Snaith, Henry J. A1 - Schmeißer, Dieter A1 - Flege, Jan Ingo T1 - Thermal stability of CH3NH3PbIxCl3-x versus [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films by X-ray photoelectron spectroscopy T2 - Applied Surface Science N2 - The thermal stability of CH3NH3PbIxCl3-x and [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 perovskite films was studied in-situ by X-ray photoelectron spectroscopy. It was found that below 85 °C both of them are relatively stable. After annealing above 85 °C, we observe a clear perovskite surface decomposition, i.e., a release of organic cations and creation of “metallic lead”. The mixed cation lead mixed halide perovskite, however, decomposes at a much lower rate. For both perovskite films, the metallic to the total lead ratio changes with the same rate for the same annealing temperatures. The release of A-site cations from the ABX3 crystal structure of perovskite and/or creation of “metallic lead” causes also a small shift of the valence band maximum towards the Fermi level. The release of [HC(NH2)2]± or Cs± is not as significant as the release of CH3NH3±; therefore, it may explain why [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 solar cells are thermally more stable. Therefore, as the stability of CH3NH3PbIxCl3-x is same as the stability of [HC(NH2)2]0.83Cs0.17PbI2.7Br0.3 below 85 °C, there must be more severe degradation pathways that are currently underappreciated on the solar cell level. KW - Hybrid organic inorganic perovskite solar cells KW - X-ray photoelectron spectroscopy KW - Film degradation KW - Thermal stability Y1 - 2020 U6 - https://doi.org/10.1016/j.apsusc.2020.145596 SN - 0169-4332 SN - 1873-5584 VL - 513 ER -