Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study

We investigate the variable temperature (100-450 K) and highpressure (p = ambient -0.74 GPa) crystal chemistry of the black perovskite formamidinium lead iodide, [(NH2)(2)CH] PbI3, using single crystal X-ray diffraction. In both cases we find a phase transition to a tetragonal phase. Our experimental results are combined with first principles calculations, providing information about the electronic properties of [(NH2) 2CH] PbI3 aswell as themost probable orientation of the [(NH2) 2CH](+) cations.