Fig. 4

SEM images observed for elemental analysis of A₃B₂X₉ films [(CH₃NH₃)₃Bi₂I₉: (a, b); (CH₃NH₃)₃Sb₂I₉: (c, d); (CH₃NH₃)₃SbBiI₉: (e, f)] grown on different substrates [TiO₂: (a, c, e); NiO: (b, d, f)]. The marked spots indicate the positions of elemental analysis, which are related to the results shown in Tables 1, 2, 3, 4, 5, and 6