Synthesis of water-dispersible, plate-like perovskites and their core-shell nanocrystals.

Shape-controlled halide perovskite nanocrystals are attractive as an emerging functional material; however, these nanocrystals are prepared using organic solvents containing alkylamines and there are few reports on the synthesis of water-dispersible halide perovskite nanocrystals. We report a simple method to prepare water-dispersible, plate-like perovskite nanocrystals by mixing a long-chain amidoamine derivative (C18AA) and potassium tetrachloropalladate (K 2 PdCl 4 ) in water. The obtained nanocrystals have a 2D layered perovskite structure represented by the chemical formula (C18AAH 2 )PdCl 4 . Furthermore, because seed-mediated growth is useful for preparing shape-controlled nanocrystals, such as rods, plates, wires and cubes, we used the water-dispersible (C18AAH 2 )PdCl 4 nanocrystals as seeds to grow (C18AAH 2 )PdCl 4 @Pt core-shell nanocrystals. The core-shell nanocrystals have rough surfaces due to the deposition of Pt on the (C18AAH 2 )PdCl 4 seeds. In addition, plate-like (C18AAH 2 )PdCl 4 @Au core-shell nanocrystals were easily obtained using this seed-mediated growth method.