Primitive Ligands Drive 1D CsPbI₃ Nanostructures with Strongly Polarized Photoluminescence

Despite growing research efforts on inorganic lead halide perovskite nanocrystals, the mechanistic understanding of nucleation and growth kinetics remains insufficient for achieving precise morphology and crystal structure control. Herein, by simply modulating the concentrations of primitive ligands (e.g., I^- and oleylamine) into conventional synthetic strategies, CsPbI₃ perovskites, ranging from zero-dimensional quantum dots to unique one-dimensional nanowires/nanorods and ginkgo leaf-like architectures, can be realized. Mechanistic studies suggests that capping agents compete for adsorption on specific crystal facets, a finding further confirmed by density functional theory (DFT) calculations. Simultaneously, the crystal structures of the products undergo a phase transition from cubic to orthorhombic symmetry driven by lattice distortion that disrupts the crystal symmetry. In addition, temperature-dependent photoluminescence studies revealed that the electron-phonon coupling strengths of longitudinal optical (LO) phonons (γ_LO = 73.14 meV and $E_{LO}\left(\hslash {\omega }_{LO}\right)$ = 28.74 meV) of CsPbI₃ nanorods were much lower (γ_LO = 103.25 meV and E_LO = 33.62 meV) than those of ginkgo leaf-like CsPbI₃ superstructures, limiting multi-phonon-assisted non-radiative pathways. As a result, CsPbI₃ nanorods display a strong polarization dependence with a polarization degree of up to ∼0.49. These results not only demonstrates novel perovskite nanocrystals but also provide a versatile platform for tailoring perovskite NCs with combined morphological diversity and tunable optical properties.