Interfacing C60 fullerene monolayer and Bi2Se3 topological insulator: From orientational ordering to prospective advanced electronic and transport properties

Integration of fullerene molecules into ultimately thin films gives rise to various fascinating effects, such as superconductivity, topology and quantum transport, however, strong substrate-mediated interaction in many hybrid molecular systems often suppresses the emergent electronic effects. In the present work, we interfaced the C₆₀ fullerene molecular film and a 3D topological insulator Bi₂Se₃ and investigated the ordering and electronic properties of the system using various experimental techniques combined with the state-of-the-art first-principles calculations. We synthesized the highly-ordered epitaxial fullerene monolayer and found it to be electronically decoupled from the substrate, due to the negligible molecule-substrate interaction, which brings it to the nearly free-standing state. We showed that electron doping and atomic intercalation enrich its functionalities, since they boost carrier concentration and effectively shift the Fermi level to the vicinity of molecular flat bands, which may enable the high-electron correlation regime and reveal a great potential of C₆₀/Bi₂Se₃ interface, as an advanced hybrid molecular 2D material.