Intramolecular Charge Polarization Dictates Intermolecular π-π Stacking Revealed in Single-Molecule junction

Abstract

A comprehensive understanding of intermolecular π-π stacking effect at the single-molecule scale is vital for advancing novel materials in fields such as organic semiconductors and optoelectronic devices. In this study, we engineered a series of molecular wires composed of pyridine, thiazole, and thiophene units arranged in various configurations. Using the scanning tunnelling microscopy-break junction (STM-BJ) technique, we investigated their single-molecule charge transport properties. Through detailed single-molecule conductance measurements, flick noise analysis, and current-voltage (I-V) studies, we demonstrated that the degree of intramolecular charge polarization is directly correlated with stacking capability. Additionally, by integrating theoretical analyses, we elucidated the mechanism for manipulating the intermolecular π-π stacking effect at single-molecule level. These insights into the fundamental principles of molecular-scale self-assembly provide a foundation for designing advanced materials based on weak intermolecular interactions.