Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals

A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH 3 NH 3 PbX 3 , X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX 2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH 3 NH 3 PbBr 3 nanowires with low pumping thresholds of 3 μJ cm −2 . A novel synthesis of colloidal CH 3 NH 3 PbX 3 , (X = Br or I) nanocrystals that does not involve the use of polar solvents is presented.