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Energy Landscape of Molecular Motion in Cubic Methylammonium Lead Iodide from First-Principles
- Bechtel, Jonathon S., Seshadri, Ram, Van der Ven, Anton
- The Journal of Physical Chemistry C 2016 v.120 no.23 pp. 12403-12410
- cations, energy, iodides, physical chemistry
- Molecular A-cation dynamics are known to play a role in the electronic properties and structure of hybrid organic–inorganic ABX₃ perovskites such as CH₃NH₃PbI₃. We calculate the full energy landscape for rigid-body rotations and translations of the methylammonium cation in the cubic phase of CH₃NH₃PbI₃. Energy barriers are calculated for combinations of molecular reorientation, on-axis rotation, and molecular translation within the unit cell. Allowing molecular translations significantly stabilizes orientations along  which we attribute to strong N–H···I interactions between CH₃NH₃⁺ and the inorganic Pb–I host lattice.