engleski

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

While the constraints on the choice of organic cations are greatly relaxed for layered two- dimensional perovskites compared to three- dimensional perovskites, the shape of the spacer cation is still subject to limitations due to the size of the inorganic pocket between four adjacent corner-sharing octahedra. To investigate the effect of the spacer cation branching on the formation of Ruddlesden–Popper (RP) structures, we performed a comprehensive investigation of structures formed using tert-butyl ammonium (t- BA). We demonstrate that in contrast to pure bromides and pure iodides, the use of mixed halides enables the formation of the t-BA2PbBr2I2 RP perovskite structure with the specific ordering of the bromide and iodide anions. The t-BA spacer, despite its branched and bulky shape that prevents its deeper penetration, is able to form significant H-bonds that lead to the stabilization of the RP assembly if the inorganic pocket is designed in such a way that the bromide anions occupy terminal axial positions, while the iodides occupy equatorial positions. We obtain excellent agreement between experimentally determined and theoretically predicted structures using global optimization via a minima hopping algorithm for layered perovskites, illustrating the ability to predict the structure of RP perovskites and to manipulate the perovskite structure by the rational design of the inorganic pocket.

Ruddlesden–Popper

nije evidentirano