The big bang of halide perovskites: The starting point of crystallization

Hybrid halide perovskites (HHPs) are very promising absorber materials for solar cells due to their high power conversion efficiency and the low-cost solution-based processing methods. We applied small angle X-ray scattering to MAPbI 3 , FAPbI 3 and MAPbBr 3 precursor solutions in different solvents (GBL, DMF, and mixtures) to gain a deeper understanding of the building blocks during the early stage of HHP formation. We present a core–shell model where the core is formed by [PbX 6 ] octahedra surrounded by a shell of solvent molecules, which explains the arrangement of the precursors in solution and how the solvent and the halide influence such arrangement.