Self-assembly of tetraphenylethene monolayer on Ag(111) surface

Abstract We investigate the self-assembly behavior of the prototypical aggregation induced emission (AIE) luminogen tetraphenylethene (TPE) on the Ag(111) surface. Thermally evaporated TPE molecules form a highly ordered, close-packed monolayer, as resolved by scanning tunneling microscopy (STM). The symmetric, non-planar conformation of TPE facilitates molecule-substrate interactions and intermolecular π-π stacking. Annealing at 60 °C preserved the structural integrity and molecular composition but induced a ∼15° tilt in the assembly orientation, attributed to thermally activated reorganization of interfacial bonds on substrate interactions. STM imaging combined with ball-and-stick modeling elucidated the molecular arrangement and identified localized bright spots as electronic signatures of the phenyl ring orientation. These results demonstrate substrate-directed assembly mechanisms relevant to designing AIE materials.