Electronic and Transport Properties of Covalent Functionalized Monolayer MoS2 by Ferrocene Derivatives

Electronic Properties of Electroactive Ferrocenyl-Functionalized MoS2

“…This feature indicates a good healing of the S-vacancy defects by the thiol-terminated molecules, in agreement with our Raman spectroscopy and PL measurements (vide supra), and is also indirectly concluded from the reported characteristic modification of the molecularly functionalized MoS 2 transistor parameters. , However, no conclusions can be drawn about the energy position of the molecular orbitals of the ferrocenyl moiety. From data reported in the literature on metal/alkyl-ferrocene/metal molecular junctions, the highest occupied molecular orbital (HOMO) of ferrocene is expected to be at ≈0.3–0.4 eV below the Au Fermi energy (HOMO of ferrocene at −5.1 eV from the vacuum level and the Au work function at −4.7/–4.8 eV). , For a ferrocene chemically grafted to MoS 2 (via a short alkyl chain (CH 2 ) 2 ), DFT calculations predict the HOMO at ∼0.6 eV above the VB of MoS 2 . Thus, we can expect to detect a contribution of the HOMO of ferrocene to the electron transfer properties if it is energetically located in the band gap of MoS 2 .…”

“…93,94 For a ferrocene chemically grafted to MoS 2 (via a short alkyl chain (CH 2 ) 2 ), DFT calculations predict the HOMO at ∼0.6 eV above the VB of MoS 2 . 34 Thus, we can expect to detect a contribution of the HOMO of ferrocene to the electron transfer properties if it is energetically located in the band gap of MoS 2 . The lowest unoccupied molecular orbital (LUMO) of ferrocene is higher (≈−0.5 V vs vacuum) and does not contribute to electron transport.…”

“…Recent theoretical calculations have validated such an approach by supporting that the transport in MoS 2 can be electrically and reversibly switched from an ON to OFF state, attributed to the grafted ferrocene. 34 Although ferrocene has been used by other groups to probe and modulate the charge transfer kinetics of MoS 2 , 35−37 to the best of our knowledge, the Samori and co-workers' study 33 constitutes the only experimental example of redox functionalization of MoS 2 .…”