Epitaxial growth of CH3NH3PbI3 on rubrene single crystal

CH3NH3PbI3 perovskite films were grown epitaxially on rubrene single crystals using the laser deposition method for the supply of the source materials (PbI2 and CH3NH3I). An atomically smooth surface with step-and-terrace structures was observed. Several types of crystal orientation were observed, which were dependent on the growth temperature and deposition conditions. For room temperature growth, the crystal orientation was correlated with the orientation of PbI2, which was also found to be grown epitaxially on the rubrene single crystal. In contrast, for growth at elevated temperatures, the crystal orientation with the smallest mismatch between rubrene and perovskite is produced. The construction of atomically ordered ideal perovskite crystals was verified. Moreover, a novel phenomenon was revealed where the octahedral PbI6 unit of PbI2 rotates vertically while retaining its lateral orientation. This growth mechanism results in a layer-by-layer growth and the construction of epitaxial perovskite films with atomic-order flat surfaces.