Synthesis of Cesium Copper Bromide Nanorods with Strong Linearly Polarized Emission

Semiconductor nanorods have often been observed to emit polarized light. This property can be useful for emission applications such as displays, optical communications, and biological labeling. Recently, many researchers have tried to replace nanocrystals containing toxic metals, such as Cd or Pb, with alternatives that can also demonstrate polarized emission. Here a low temperature injection (LTI) method with a relatively short chain octylammonium bromide ligand precursor is used to slow down the nanorod formation reaction and the controlled anisotropic growth of Cs3Cu2Br5 nanorods is realized, producing more uniform samples of nanorods with higher aspect ratios than those previously reported. Such nanorods exhibit a very high degree of polarization (DOP) of 0.88 +/- 0.04 for single rods, and a corresponding polarization anisotropy of 0.26 for the sample population, both the highest yet reported for any perovskite-like material. Further this method can be extended to produce Cs3Cu2Cl5 nanorods as well, allowing for broad tuning of their optical properties.