In-situ X-ray diffraction reveals the degradation of crystalline CH3NH3PbI3 by water-molecule collisions at room temperature

We have developed a vacuum-compatible chamber for in-situ X-ray diffraction ( XRD) studies and have used it to characterize the changing crystal structure of an inorganic-organic hybrid perovskite material, CH3NH3PbI3 ( MAPbI(3)), during interactions with water vapor at room temperature. In the XRD spectra, we have observed the degradation of MAPbI(3) and the creation of MAPbI(3) hydrates, which follow simple rate equations. The time constant for the degradation of MAPbI(3) during accelerated aging suggests that multiple collisions of water molecules with the MAPbI3 crystal trigger the degradation of the crystal. (C) 2018 The Japan Society of Applied Physics