Tuning the Interfacial Electronic Structure of MoS₂ by Adsorption of Cobalt Phthalocyanine Derivatives

We investigate the interfacial electronic structure of n-type bulk MoS2 upon the adsorption of CoPc and CoPcF16 monolayers and few layers using advanced spectroscopic techniques. These include X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), angle-resolved photoelectron spectroscopy (ARPES), and ultraviolet photoelectron spectroscopy (UPS). Our findings indicate that the adsorption of CoPc enhances the degree of n-doping at the interface with MoS2. In contrast, CoPcF16 acts as an electron acceptor and results in a nearly intrinsic position of the Fermi level of MoS2. Furthermore, we note the formation of an induced gap state near the valence band maximum for monolayer CoPcF16 on MoS2. These observations underscore the potential to fine-tune the interfacial electronic properties of transition metal dichalcogenides through molecular functionalization for application in optoelectronic devices.