title: CH3NH3PbI3: precise structural consequences of water absorption at ambient conditions.
abstract: The crystal structure of the pristine (I) and aged (II) crystals of CH3NH3PbI3(hereafter MAPbI3) hybrid organic-inorganic lead iodide has been studied at 293 K with high-precision single-crystal X-ray diffraction using a synchrotron light source. We show that (I) and (II) are characterized by an identical tetragonal unit cell but different space groups: I422 for (I) and P42212 for (II). Both space groups are subgroups of I4/mcm, which is widely used for MAPbI3. The main difference between (I) and (II) comes from the difference in hydrogen bonds between the MA+cation and the PbI3framework which is the direct consequence of H2O insertion in the aged crystal (II).
authors.affiliation: Laboratory of Physics of Complex Matter, Ecole polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Alla
authors.initials: A
authors.lastname: Arakcheeva
authors.affiliation: SNBL, ESRF, 71 Avenue des Martyrs, 38043 Grenoble CEDEX 9, France.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Chernyshov
authors.affiliation: Laboratory of Physics of Complex Matter, Ecole polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Massimo
authors.initials: M
authors.lastname: Spina
authors.affiliation: Laboratory of Physics of Complex Matter, Ecole polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: László
authors.initials: L
authors.lastname: Forró
authors.affiliation: Laboratory of Physics of Complex Matter, Ecole polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Endre
authors.initials: E
authors.lastname: Horváth
keywords: aged MAPbI3; hybrid organic–inorganic lead iodide; hydrogen bonding; perovskite; solar cells