Ethanol induced structure reorganization of 2D layered perovskites (OA)2(MA)n-1PbnI3n+1

Abstract 2D perovskite materials have attracted increasing attention in the last few years due to their optical tunability. However, how to control the structure of these materials is still one of the key challenges. In this work, by using photoluminescence microscopy and XRD characterization, we found that ethanol treatment can induce the reorganization of the crystal structure of 2D perovskite materials. The ethanol molecules can insert into (OA)2(MA)Pb2I7 (OA = CH3(CH2)7NH3; MA = CH3NH3) crystal lattice and preferentially dissolve MA ions reducing the MA/OA ratio. During the recrystallization, new (OA)2PbI4 phase forms due to the low MA/OA ratio. On the other hand, adsorption of ethanol can induce the photoluminescence (PL) enhancement by passivation of the surface defects. Consequently, PL intensity increases and decreases as the activation/deactivation of the quenching defects. These results provide a possible way to optimize the crystal structure of 2D perovskite under mild condition.