Seed-Mediated Anisotropic Growth of One-Dimensional Cs ₅ Cu ₃ Cl ₆ I ₂ Nanorods and Their Polarization-Dependent Optical Response

Low-dimensional Cu(I)-based metal halides have attracted considerable interest because of their low toxicity, stability, and unique self-trapped exciton (STE)-driven luminescence, with blue-emitting Cs5Cu3Cl6I2 demonstrating considerable potential for next-generation optoelectronics. In this article, we present a seed-mediated anisotropic growth method to synthesize one-dimensional (1D) Cs5Cu3Cl6I2 nanorods (NRs) and examine their polarization-dependent optical behaviors. We achieve NRs with aspect ratios (ARs) exceeding 50 by injecting highly reactive Cs5Cu3Cl6I2 seeds into a ligand solution with a skewed acid-to-amine ratio. These NRs exhibit a remarkable degree of polarization of 0.76 when aligned in thin films, demonstrating a significant anisotropic interaction with linearly polarized light. The effects of the ligand concentration and growth temperature on the NR morphology are explored, and density functional theory calculations are used to clarify the underlying anisotropic growth mechanism. The synthesized Cs5Cu3Cl6I2 NRs demonstrate the potential for optoelectronic applications requiring controlled polarization, such as advanced displays and photonic devices.