Molecular charge transfer complexes are an interesting class of materials due to their promising applications in molecular electronic devices. Understanding the charge transfer between donor and acceptor molecules at the nanoscale is crucial for the ongoing development and optimization of those devices. In this thesis, we investigate charge-transfer processes within prototype mixed molecular systems on the singlelayer molybdenum disulfide (SL-MoS2) on Ag(111). The characterization of molecules on SL-MoS2 is motivated by the fact that SL-MoS2 electronically decouples molecules from the metal substrate and enables us to resolve the electronic properties (vibronic states and charge transfer processes) of an almost isolated molecule. Spectroscopic measurements of SL-MoS2 on Ag(111) reveal the semiconducting bandgap. We also observe a moiré pattern due to the lattice mismatch between SL-MoS2 and Ag(111).
