The role of solvents in the formation of methylammonium lead triiodide perovskite

Metal halide perovskites (MHPs) are gaining increasing attention as low-cost, high-performance semiconductors for optoelectronics. In particular, their solution processing is compatible with the large-scale manufacturing of thin-film devices, including solar cells and light-emitting diodes. Understanding coordination chemistry in precursor-solvent atomistic mechanisms film formation great importance optimizing optoelectronic properties final films. Using methylammonium lead triiodide (MAPbI3) an example, we study complex evolution molecular species from to initial stage crystallization by using a combination density functional theory (DFT) calculations ab-initio dynamics (AIMD) simulations. We focus on widely employed solvents DMSO DMF, analyze structures energies iodoplumbate complexes form simple [PbImLn]2−m polymeric iodoplumbates ([PbImLn]2−m)x. Based calculated enthalpies, propose reaction schemes MAPbI3 DMSO, DMF DMF-DMSO binary solvent explain advantages solvent. highlight important role NH…O hydrogen bonds monomers. Our indicate unbalanced at several elementary steps either (formation [PbI4Ln]2− being highly favourable) or [PbI5Ln]3− retarded). Mixing small amount gives rise better balance and, therefore, potentially equilibria overall process quality perovskite