Quantum Transport through Asymmetrical Molecular channel Azulene: Role of Orbital Interference

Abstract

We investigate electron transport through azulene molecule with four distinct electrode contact geometries using the non-equilibrium Green's function formalism within the tight-binding Hamiltonian. Employing the Q-matrix approach, we analyze quantum interference (QI) among the molecular orbitals in each contact configuration. Our results reveal distinct transmission profiles and varying current responses among configurations, with the configuration 1-3 displaying the highest conductivity at higher bias due to strong constructive interference of the Highest Occupied Molecular Orbital (HOMO). Conversely, configuration 5-7 exhibit weak conductance and antiresonance at the Fermi energy, attributed to dominant destructive interference among the frontier molecular orbitals. Configuration 2-6 is found to exhibit asymmetric I-V characteristics, due to the dipolar nature of the azulene molecule. These findings underscore the significance of QI effects in shaping the transport properties of azulene, and molecule-based devices in general.