Understanding the Transformation of 2D Layered Perovskites to 3D Perovskites in the Sonochemical Synthesis
Modasser Hossain, Trupthi Devaiah Chonamada, Pralay K. Santra
Abstract
Two-dimensional (2D) layered Ruddlesden–Popper metal halide perovskites (MHPs) show enhanced stability compared to three-dimensional (3D) MHPs. The general formula of 2D layered perovskite is L2An–1MnX3n+1, where L is the large organic spacer and n is the number of metal octahedra. However, the syntheses of such 2D layered perovskites yield a mixture of 3D and 2D layered perovskites with different layers of the metal octahedra. In this work, we have synthesized 2D layered (MA)n+1PbnI3n+1 perovskite by the sonochemical method. We have shown that the dimensionality n can be controlled by the sonication time and reaction temperature. Using absorption and photoluminescence spectroscopy, we have probed the reaction and growth mechanisms of the 2D layered perovskites and their transformation to 3D MAPbI3 (MAPI). At both lower temperature and early stage of the reaction, 2D layered perovskites with lower dimensionality form and eventually covert to higher-dimensional layered perovskite before transforming to 3D perovskites. The dissimilarity in the solubility of the precursors (PbI2 and MAI) is responsible for such transformations. We show that these mixed (2D layered and 3D MAPI) perovskites can be used to fabricate a white light-emitting diode.