Room temperature atomic layer deposited Al2O3 on CH3NH3PbI3 characterized by synchrotron-based X-ray photoelectron spectroscopy

An ultrathin Al2O3 film deposited on methylammonium lead triiodide (CH3NH3PbI3) perovskite has the capability to suppress the carrier recombination process and improve the perovskite solar cells efficiency and stability. However, annealing at temperatures higher than 85 °C degrades the CH3NH3PbI3 perovskite film. The X-ray photoelectron spectroscopy study performed in this work indicates that it is possible to grow Al2O3 by atomic layer deposition on the perovskite at room temperature, however, besides pure Al2O3 some OH groups are found and the creation of lead and iodine oxides at the Al2O3/CH3NH3PbI3 interface takes place.