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

Fabrication of well-ordered molecular films and further tuning their structural and electronic properties is crucial in enhancing the performance of the on-based organic devices. Herein, by high-resolution scanning tunneling microscopy and density functional theory calculation, we demonstrate the on-surface fabrication of well-organized vanadyl phthalocyanine (VOPc) membranes with diverse characteristics on the binary alloy monolayer. The molecular configurations, structures, and orbitals are clearly clarified in the submolecular level. On Ag2Sb/Ag(111), the VOPc membrane exhibits the fourfold symmetric unit cell comprising one centered and four cornered O-up molecules with two distinct stacking orientations. On the contrary, on Cu2Sb/Cu(111), all VOPc molecules adopt the O-down configuration and uniform orientations. The tunneling conductance spectra unveil a semiconductor signature but with different occupied orbitals for both VOPc membranes. These contrasting features are resulted from the diverse molecule-substrate interaction relating to the different charge transfer of alloy surfaces. Our study may open up a new route for modifying the structures and electronic states of the molecular films by applying surface alloy effects.