The origin of the dissolution of methylammonium lead trihalide (MAPI) crystals in liquid water is clarified by finite-temperature molecular dynamics by developing a MYP-based force field (MYP1) for water-MAPI systems. A thermally activated process is found with an energy barrier of 0.36 eV consisting of a layer-by-layer degradation with generation of inorganic PbI2films and solvation of MA and I ions. We rationalize the effect of water on MAPI by identifying a transition from a reversible absorption and diffusion in the presence of vapor to the irreversible destruction of the crystal lattice in liquid due to a cooperative action of water molecules. A strong water-MAPI interaction is found with a binding energy of 0.41 eV/H2O and wetting energy of 0.23 N/m. The water vapor absorption is energetically favored (0.29 eV/H2O), and the infiltrated molecules can migrate within the crystal with a diffusion coefficient D = 1.7 Ã 10-8cm2/s and activation energy of 0.28 eV
Collective molecular mechanisms in the CH3NH3PbI3 dissolution by liquid water
Caddeo, Claudia;Meloni, Simone;Filippetti, Alessio;
2017-01-01
Abstract
The origin of the dissolution of methylammonium lead trihalide (MAPI) crystals in liquid water is clarified by finite-temperature molecular dynamics by developing a MYP-based force field (MYP1) for water-MAPI systems. A thermally activated process is found with an energy barrier of 0.36 eV consisting of a layer-by-layer degradation with generation of inorganic PbI2films and solvation of MA and I ions. We rationalize the effect of water on MAPI by identifying a transition from a reversible absorption and diffusion in the presence of vapor to the irreversible destruction of the crystal lattice in liquid due to a cooperative action of water molecules. A strong water-MAPI interaction is found with a binding energy of 0.41 eV/H2O and wetting energy of 0.23 N/m. The water vapor absorption is energetically favored (0.29 eV/H2O), and the infiltrated molecules can migrate within the crystal with a diffusion coefficient D = 1.7 Ã 10-8cm2/s and activation energy of 0.28 eVFile | Dimensione | Formato | |
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