Complexation-Mediated Diffusion-Limited Crystal Growth: A General Framework for Anisotropic Crystal Growth in Cu-Based Perovskites

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 Cs3Cu2I5 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 > 103) 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 Cs3Cu2I5 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.