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) andP42212 for (II). Both space groups are subgroups ofI4/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).