Phase-selective synthesis of lead-free CsMnBr3 and Cs3MnBr5 nanocrystals dependent on solvent concentration

We demonstrate the crystal phase-selective synthesis for lead-free cesium manganese bromine perovskite nanocrystals synthesized by the modified hot-injection method due to changing the concentration of solvent (trioctylphosphine; TOP). The compositions synthesized were determined by the amount of TOP solvent, and the structure phase of the nanocrystals was selected from hexagonal CsMnBr 3 to tetragonal Cs 3 MnBr 5 as the amount of TOP solvent increased. The emission peaks of CsMnBr 3 and Cs 3 MnBr 5 nanocrystals were observed at 650 nm (red) and 520 nm (green), respectively. After a durability test at 85°C and 85% humidity for 24 h, the lead-free perovskite CsMnBr 3 nanocrystal powder maintained its initial emission intensity, and the metal halide Cs 3 MnBr 5 nanocrystal powder exhibited an increase in red emission due to the post-synthesis of CsMnBr 3 nanocrystals.