Modulating the Switching Performance of Fulgimide-Based Molecular Junctions through Atomic Substituents

The development of molecular switches with high stability and performance continues to be a focal point in the field of molecular electronics. Among these, fulgimide, a representative photochromic molecule, holds significant promise as a photoswitch due to its capability to undergo reversible conformational changes. In this study, the nonequilibrium Green’s function (NEGF) method, combined with density functional theory (DFT), is employed to investigate the transport properties of fulgimide-based molecular junctions derived from the furan (O), thiophene (S), and indole (N) classes. Key calculations, including current–voltage (I–V) characteristics, transmission spectra, and switching ratios, demonstrate that fulgimide-based molecular junctions exhibit pronounced switching behavior and negative differential resistance effects. The observed switching ratio (O > S > N) suggests that modifying the central molecular unit enables effective tuning of the junction’s properties. Furthermore, detailed analyses using the molecular projected self-consistent Hamiltonian (MPSH) and real-space eigenchannels provide valuable insights into the underlying mechanisms driving the observed transport phenomena.