Monolayer methylammonium lead iodide films deposited on Au(111)

•Monolayer MAPbI3 films were deposited on Au(111) substrates by vapor deposition under ultrahigh vacuum conditions.•The atomic structure of the monolayer MAPbI3 films was characterized by high-resolution scanning tunneling microscopy (STM).•During STM scanning, three substructures of the monolayer MAPbI3 can convert into one another.