Hybrid perovskites have been the object of intense research in recent years due to the exceptional photovoltaic properties of methylammonium lead trihalide (MAPI) solar cells. The large lead and halide ions are at the origin of the MAPI softness and the need of organic MA cations to meet the tolerance factor requirement of a stable perovskite structure. In addition, the ionic character of the crystal favors the migration of ions (in particular iodines) with effects on conductivity, mass transport and unconventional hysteretic current-voltage transients. MAPI is accordingly a "dynamical hybrid crystal" in which finite-temperature dynamics, molecular entropy and defects-related phenomena are crucially important[4,5].
Here, we show that, despite the complexity of MAPI, their main properties are successfully reproduced by a simple classical interatomic potential (MYP)[1,3,6] and we review a number of recent applications related to molecular ordering,vibrational properties, point-defects diffusivity, thermal transport.
In particular, we discuss the possibility to extend the models to include the interactions of MAPI with water. It is possible in this way to study the fast degradation in water and to rationalize the transition from a reversible transformation in presence of vapor to an irreversible dissociation into insoluble lead iodide and MAI in presence of liquid water.
- A. Mattoni, A. Filippetti, C Caddeo, J. Phys. Condens. Matter 2017, 29, 43001.
- P. Delugas, C. Caddeo, A. Filippetti, and A. Mattoni, J. Phys. Chem. Lett. (2016), 7, 2356.
- A. Mattoni, A. Filippetti, M.I. Saba, and P. Delugas, J. Phys. Chem. C (2015),119, 17421.
- A. Mattoni, A. Filippetti, M.I. Saba, C. Caddeo, and P. Delugas, J. Phys. Chem. Lett. (2016), 7, 529.
- M. I. Dar, G. Jacopin, S. Meloni, A. Mattoni, et al. Sci. Adv. (2016), e1601156
- T . Hata, G.Giorgi, K. Yamashita, C. Caddeo, and A. Mattoni, J. Phys. Chem. C (2017), 121, 3724.
- C. Caddeo, C. Melis, M.I. Saba, A. Filippetti, L. Colombo and A. Mattoni, Phys. Chem. Chem. Phys. (2016), 18, 24318–24324.
- C. Caddeo, M.I. Saba, S. Meloni, A. Filippetti, and A. Mattoni, submitted (2017)