Topological Modifications of Layered Materials Beyond 2D Morphology

Morphological control of layered materials has crucial implications on modern electronics and photonics. However, layered materials do not naturally grow beyond 2D morphologies due to their inherent in-plane symmetry. Organic-inorganic hybrid lattice, however, presents unique crystal structure to tackle this challenge. For insance, layered perovskites readily synergize chemical tunability and solution processability of organics with optical and electronic properties of traditional inorganic crystals. Using layered perovskite as a structural template, I'll present a few molecular templating approaches to manipulate the network topology in the organic sublattice and achieve exciting morphological control on layered materials beyond 2D morphologies.<br/> <br/>The first approach creates an 1D organic network in layered perovskites using robust and directional hydrogen bonding from aromatic carboxylic acids. This molecular templating method restricted the crystal growth along all directions except for a designed primary axis.<br/>and promoted 1D growth (1). Our approach is widely applicable to synthesize a range of high-quality layered perovskite nanowires with large aspect ratios and tunable chemical compositions, including the deterministic synthesis of longitudinal heterostructures. These nanowires form exceptionally well-defined and flexible cavities that exhibited a wide range of unusual optical properties beyond those of conventional perovskite nanowires. We observed anisotropic emission polarization, low-loss waveguiding and efficient low-threshold light amplification.<br/> <br/>The second approach exploits the asymmetric strain built in such an 1D network topology, which created a primary bending axis in layered materials to allow for the automatic generation of morphological chirality during crystal growth. Helicoids or helical ribbons can be synthesis in a scalable fashion. The underlying mechanism is proposed to be a type of "incompatible elasticity" in well resonance with the chiral opening of seed pods (2). Our ongoing efforts to elucidate this mechanism via molecular dynamics modeling and experimental single crystal analysis will be discussed.<br/> <br/>(1) Shao, W., et al. Science, 2024, 384(6669), 1000–1006. https://doi.org//10.1126/science.adl0920<br/>(2) Armon, S. et al. Science, 2011, 333(6050), 1726–1729. https://doi.org/10.1126/science.1203874