Formation of layered perovskite structure by folding monolayer during compression.

The morphology and layered structure of an alkyl ammonium bromide ultrathin film prepared on an aqueous solution of lead bromide were investigated on the basis of surface pressure-area curve measurements, reflection spectrum measurements, X-ray reflectivity measurements and atomic force microscopic observations. It became apparent that the layered structure sandwiched a two-dimensional inorganic layer between two organic monolayers was formed by folding the monolayer by compression on an aqueous PbBr2 solution.