Enhanced quantum transport in all-carbon molecular junctions based on topologically tailored cyclocarbon nanostructures

The breakthrough synthesis of cyclo[18]carbon (C18) has ignited considerable interest in its structural topology and technological potential. The molecule's fully conjugated electronic structure positions it as an exceptional candidate for functional molecular electronics, while its inherent chemical versatility enables the design of tailored derivatives. Using first-principles calculations combining density functional theory with non-equilibrium Green's function formalism, we systematically investigate quantum transport in C18/C36-based molecular junctions interconnected via monatomic carbon chain electrodes. Our calculation results reveal distinct quantum transport behaviors across derivatives, including linear Ohmic conduction, pronounced negative differential resistance, and molecular switching characteristics. The mechanistic analysis demonstrates that the spatial delocalization and energy-level broadening of frontier molecular orbitals fundamentally dictate these transport regimes. This work establishes critical structure-transport correlations and provides a design framework for developing advanced all-carbon molecular devices based on topologically tailored cyclocarbon nanostructures.