title: Clean, cleaved surfaces of the photovoltaic perovskite.
abstract: The surface of a material is not only a window into its bulk physical properties, but also hosts unique phenomena important for understanding the properties of a solid as a whole. Surface sensitive techniques, like ARPES (Angle-resolved photoemission spectroscopy), STM (Scanning tunneling microscopy), AFM (Atomic force microscopy), pump-probe optical measurements etc. require flat, clean surfaces. These can be obtained by cleaving, which is usually possible for layered materials. Such measurements have proven their worth by providing valuable information about cuprate superconductors, graphene, transition metal dichalcogenides, topological insulators and many other novel materials. Unfortunately, this was so far not the case for the cubic, organo-metallic photovoltaic perovskite which morsels during the cleavage. Here we show a method which results in flat, clean surfaces of CH3NH3PbBr3which allows surface sensitive measurements, badly needed for the understanding and further engineering of this material family.
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Márton
authors.initials: M
authors.lastname: Kollár
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Luka
authors.initials: L
authors.lastname: Ćirić
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland.
authors.forename: J Hugo
authors.initials: JH
authors.lastname: Dil
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland.
authors.forename: Andrew
authors.initials: A
authors.lastname: Weber
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institute, CH-5232, Villigen, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Muff
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Henrik M
authors.identifier: http://orcid.org/0000-0002-8832-8865
authors.initials: HM
authors.lastname: Ronnow
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Bálint
authors.initials: B
authors.lastname: Náfrádi
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Benjamin Pierre
authors.initials: BP
authors.lastname: Monnier
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Jeremy Scott
authors.initials: JS
authors.lastname: Luterbacher
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland. laszlo.forro@epfl.ch.
authors.forename: László
authors.initials: L
authors.lastname: Forró
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
authors.forename: Endre
authors.initials: E
authors.lastname: Horváth