Origin of Pressure-Induced Phase Transition and Metallization in Hybrid Halide Perovskites

ORAL

Abstract

Hybrid halide perovskites are promising optoelectronic materials due to their favorable electronic properties and low cost. Here we investigate the effects of high pressure on the structural and electronic properties of (MA)PbI3 (MA = CH3NH3+) using first-principles density functional theory (DFT) calculations. Our calculations predict that with increasing external pressure, the cubic high-pressure Im-3 phase becomes more energetically favorable for the MA cations than the orthorhombic low-pressure Fmmm phase, leading to a predicted phase transition at 0.22 GPa, in good agreement with the experiment (~0.3 GPa). With increasing pressure we also find severe octahedral tilting occurs at 6 GPa, introducing I 5p – I 5p* antibonding and Pb 6p – Pb 6p bonding character into the valence band maximum (VBM) and the conduction band minimum (CBM) states, respectively. This leads to a different trend in the VBM and CBM energies under compression compared to their behavior below 6 GPa. Our DFT calculations show that this trend eventually leads to metallization at significantly higher pressures.

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Presenters

  • Jung-Hoon Lee

    University of California, Berkeley

Authors

  • Jung-Hoon Lee

    University of California, Berkeley

  • Jeffrey B Neaton

    Molecular Foundry, Lawrence Berkeley National Lab, University of California, Berkeley, Lawrence Berkeley National Laboratory, Molecular Foundry, Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, UC Berkeley/Lawrence Berkeley Natl Lab, Lawrence Berkeley National Lab, Berkeley, CA, Physics, University of California, Berkeley, Molecular Foundry, LBNL; UC Berkeley; Kavli ENSI, Lawrence Berkeley National Laboratory, University of California - Berkeley, Kavli Energy NanoSciences Institute at Berkeley