Film formation mechanisms in mixed-dimensional 2D/3D halide perovskite films revealed by in situ grazing-incidence wide-angle X-ray scattering

Mixed-dimensional 2D/3D hybrid halide perovskites retain the stability of 2D perovskites (formula (A')2(A)(n-1)PbnI3n+1) and long diffusion lengths of the 3D materials (AMX3), thereby affording devices with extended stability as well as state-of-the art efficiencies approaching those of the 3D materials. These films are made by spin-coating precursor solutions with an arbitrarily large average layer thickness n ((n) > 7) to give films with both 2D and 3D phases. Although the 2D and 3D perovskite film formation mechanisms have been studied, little is understood about composite 2D/3D film formation. We used in-situ grazing-incidence wideangle scattering with synchrotron radiation to characterize the films fabricated from precursor solutions with stoichiometries of (BA)(2)(MA)(n-1)PbnI(3n+1) ((n) = 3, 4, 5, 7, 12, 50, and infinity N (MAPbI(3))). Four different mechanisms are seen depending on the stoichiometry in the precursor solution. Kinetic analysis shows faster and earlier growth of the solvate with increasing < n >.

Automated summary

Mixed-dimensional 2D/3D hybrid halide perovskites combine the stability of 2D perovskites with the long diffusion lengths of 3D materials, showing four different formation mechanisms depending on the stoichiometry in the precursor solution. Kinetic analysis reveals faster and earlier growth of the solvate with increasing <n>.