  Solar to power conversion certified efficiencies of formamidinium lead iodide
based single-junction perovskite solar cell is now 26%, all
perovskite-perovskite tandem $\sim$28%, and the perovskite-silicon tandem solar
cell is $\sim$34% going beyond gallium arsenide solar cells. Therefore, it is
now one of the most promising materials for generating cheaper sunlight-based
electricity. This material has two commonly known polymorphs; one is a
thermodynamically stable yellow hexagonal phase. The other one is a metastable
black perovskite phase: a powerful photo-active material. Thousands of
experiments have been performed to produce the highly crystalline photoactive
phase of formamidinium lead iodide. Despite that, PSCs often suffer from poor
reproducibility and stability. One of the root cause is the lack of control
over their synthesis, i.e. crystallization process, where one of the main
quests is to synthesize and stabilize corner-sharing defects-free photoactive
perovskite form of pure or doped black perovskite form of formamidinium lead
iodide and prevent the formation of hexagonal phases. Thus, for the rapid
industrialization of perovskite based solar farms to combat global rising
temperatures: it is all-important to understand the polymorph selective
nucleation of formamidinium lead iodide from its precursors. Towards this
ultimate goal, here we perform molecular simulations of the nucleation of
formamidinium lead iodide from solution. This study aims to take the primary
steps for the all-atoms simulations of the polymorph selective crystallization
of halide perovskites.
