ABSTRACT The rational synthesis of 1D lead‐free perovskite nanostructures remains challenging due to complex precursor chemistry that defies classical crystal growth models. Here, we establish and experimentally validate a Complexation‐Mediated Diffusion‐Limited Growth (CMDLG) framework that integrates coordination chemistry with mass transport kinetics to direct the growth of Cs 3 Cu 2 I 5 nanowires (NWs). This framework transforms precursor complexation from a synthetic hurdle into a powerful tool for directing anisotropic growth. By engineering the solvent environment to stabilize bulky iodocuprate complexes, we restrict mass transport and introduce a kinetic barrier, complex dissociation, at the growth front, driving the system into a diffusion‐limited regime. This enables tunable synthesis of faceted microwires in polar solvents and ultralong, uniform NWs (aspect ratio > 10 3 ) in low‐polarity 2‐pentanone. In situ optical microscopy captures complex‐rich zones along NW sidewalls and depletion zones at growing tips, providing direct evidence for CMDLG. The resulting single‐crystalline Cs 3 Cu 2 I 5 NWs exhibit excellent structural and optical quality, forming lyotropic liquid crystals after surface passivation and self‐assembly. Shear‐aligned, photopolymerized NW‐polymer composite films show strong perpendicular polarized emission ( p = 0.31) and enhanced chemical stability. The CMDLG framework provides a unified paradigm for understanding and predicting anisotropic growth in complex perovskite and related inorganic systems.
Lee et al. (Mon,) studied this question.