Tuning configurations and orbitals of vanadyl phthalocyanine on transition metals via surface alloy effect.

This article focuses on the on-surface fabrication and characterization of vanadyl phthalocyanine (VOPc) molecular membranes on binary alloy monolayers Ag₂Sb/Ag(111) and Cu₂Sb/Cu(111). Using high-resolution scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, the study reveals that VOPc forms well-ordered membranes with distinct molecular configurations: an O-up configuration with a fourfold symmetric unit cell on Ag₂Sb/Ag(111), and an O-down configuration with uniform orientation on Cu₂Sb/Cu(111). Both membranes exhibit semiconducting behavior but differ in their highest occupied molecular orbital (HOMO) states, attributed to variations in molecule–substrate interactions and charge transfer effects inherent to the alloy surfaces. These findings demonstrate the potential of surface alloy engineering to tune the structural and electronic properties of organic semiconductor films, which may enhance the performance of organic electronic and optoelectronic devices.