(775a) Investigating the Role of Lewis Acid-Base Interactions in Halide Perovskite Solutions
AIChE Annual Meeting
2021 Annual Meeting
Computational Molecular Science and Engineering Forum
Practical Applications of Computational Chemistry and Molecular Simulation III
Tuesday, November 16, 2021 - 1:50pm to 2:10pm
- Quantify the binding affinity of Lewis bases (solvents) towards Lewis acids (perovskite salts and cations) â over 600 combinations were explored.
- Identify metrics towards selecting ideal solvent candidates for perovskite processing without the need for additional computation (rules of thumb and simple linear models).
- Uncover their impact on the solution precursors and solid-state intermediate structures preceding the final perovskite film.
A key result from this study is that no single metric can describe solvent interactions towards A-site cations (e.g., Cs+) and B-site cation species (PbI2). For example, the Gutmann donor number (DN), a Lewis affinity scale metric that has gained popularity in recent years, adequately describes solvent interactions with isolated B-cation salt complexes (BXn). Here B represents B-site cations of group 14 and 15 elements (Pb, Sn, Ge, Bi, and Sb) and X represents the perovskite halide ions (Cl-, Br- and I-). On the other hand, the lithium cation affinity (LCA) scale best describes solvent interactions towards group 1 A-site cations (Cs+ and Rb+), while the methyl ammonium cation affinity (MACA) approximates the affinity of solvents to the methylammonium cation (MA+) in perovskite solutions. Using computation, we elucidate how the affinity of solvents towards these Lewis acids can impact the formation of higher order iodoplumbate complexes and the intercalation of A-site cation species into the perovskite framework â two key reactions occurring in solution that are essential to the nucleation and growth of the final perovskite film. Finally, through leveraging our generated metrics, one could design processing protocols that optimize the quality of the final perovskite film via judicious solvent selection.