Decoupled Electronic Structure and Raman Spectroscopy of Few-Layer C₆₀ on a Supramolecular Spacer Layer

Large-scale supramolecular networks based on a 1:1 cyanuric acid and melamine (CA·M) complex were successfully fabricated on reconstructed Au(100) surfaces under ambient conditions. When employed as a spacer layer in ultrahigh vacuum environments, these networks facilitated the investigation of electronic decoupling effects in overlying fullerene layers. The geometric and electronic structures of self-assembled C₆₀ layers on CA·M/Au (100) were systematically characterized using scanning tunneling microscopy/spectroscopy (STM/STS). STM/STS measurements revealed a large HOMO-LUMO energy gap of 4.1 eV within the C₆₀ domains. These observations were further supported by X-ray photoelectron spectroscopy, which confirmed the electronic decoupling effect induced by the spacer layer. Notably, this macroscopic decoupling enables the detection of Raman scattering signals from few-layer C₆₀ films deposited on CA·M precoated single-crystal gold substrates─a result that would otherwise be obscured by strong substrate interactions. These findings highlight the potential of the CA·M supramolecular network as an effective decoupling layer for future applications in molecular electronics.