Mixed Halide Ordering as a Tool for the Stabilization of Ruddlesden- Popper Structures

J Ovcar and TL Leung and L Grisanti and Z Skoko and M Vrankic and KH Low and SX Wang and PY You and H Ahn and I Loncaric and AB Djurisic and J Popovic, CHEMISTRY OF MATERIALS, 34, 4286-4297 (2022).

DOI: 10.1021/acs.chemmater.1c03815

While the constraints on the choice of organic cations are greatly relaxedfor layered two-dimensional perovskites compared to three- dimensional perovskites, theshape of the spacer cation is still subject to limitations due to the size of the inorganicpocket between four adjacent corner-sharing octahedra. To investigate the effect of thespacer cation branching on the formation of Ruddlesden-Popper (RP) structures, weperformed a comprehensive investigation of structures formed usingtert-butyl ammonium(t-BA). We demonstrate that in contrast to pure bromides and pure iodides, the use ofmixed halides enables the formation of thet-BA2PbBr2I2RP perovskite structure with thespecific ordering of the bromide and iodide anions. Thet-BA spacer, despite its branchedand bulky shape that prevents its deeper penetration, is able to form significant H-bonds that lead to the stabilization of the RPassembly if the inorganic pocket is designed in such a way that the bromide anions occupy terminal axial positions, while the iodidesoccupy equatorial positions. We obtain excellent agreement between experimentally determined and theoretically predictedstructures using global optimizationviaa minima hopping algorithm for layered perovskites, illustrating the ability to predict thestructure of RP perovskites and to manipulate the perovskite structure by the rational design of the inorganic pocket

Return to Publications page