Abstract:

Anisotropy across different length scales can be harnessed to direct the crystallization of nanoscale solids with controlled size, shape, and faceting, giving rise to emergent optical and electronic states. In two-dimensional (2D) van der Waals (vdW) phases, strong in-plane covalent bonding enables the preparation of stable, atomically flat monolayers at the 2D limit. By contrast, the rational synthesis of one-dimensional (1D) vdW solids – composed of 1D units with strong intrachain covalent bonding held together by weak interchain vdW forces – remains considerably less developed. Establishing chemical methods to control both the interchain and intrachain interactions provides a pathway to assemble 1D vdW solids into nanowire, nanoribbon, and nanosheet morphologies that support properties ranging from higher-order topological modes to confined excitonic states. This dissertation describes bottom-up synthetic strategies for the synthesis of nanostructures from 1D and quasi-1D vdW solids. First, we develop a route to synthesize Bi4I4 nanosheets with controlled size and orientation, enabling experimental access to the predicted quantum states on the (001) surface. Building on this framework, we demonstrate the deterministic synthesis of the quasi-2D vdW phase, GaTe, producing luminescent nanoscale and mesoscale structures. Finally, we establish a growth strategy for ultra-long Bi2S3 nanowires, resulting in strain-induced indirect-to-direct-gap enhancement and increased luminescence intensity. Together, these results advance the methodologies for directing the synthesis of low-dimensional vdW phases with 1D-like substructures. By coupling structural anisotropy with synthetic control, this work establishes design principles for accessing emergent physical states and lays the foundation for their integration into next-generation optical, electronic, and quantum devices.