Development and evaluation of force fields for studying the formation of metal halide perovskites from solution.

Metal halide perovskites have rapidly evolved into an efficient, low-cost alternative to conventional photovoltaic materials. Devices with power conversion efficiencies over 20% have been made within only a decade of their first application. Solution processability, earth-abundant precursors, a high absorption coefficient and tuneable bandgap make hybrid perovskites even more attractive. However, further development is necessary before perovskite solar cells can be widely adopted by industry. For instance, they cannot currently be printed at scale and degrade in the presence of water. Even though many experimental studies have attempted to overcome these challenges, a molecular level understanding of how they form from solution and degrade is still lacking.

Molecular modelling is a useful technique to explore experimentally inaccessible atomic level phenomena.  A couple of attempts have been made recently to parameterise force fields for the study of metal halide perovskites, with some success at reproducing solid-state properties. However, a transferable force field that can accurately describe both solution- and solid-state properties is still lacking.

This seminar will describe the development of a robust polarisable force field for studying the formation and degradation of lead halide perovskites and provide insight into the thermodynamics of the precursor ions in solution and the mechanism of growth of MAPbI₃.