Organic Molecule-Induced Charge Exchange in MoS ₂ FETs: Experimental and Theoretical Insights

This work investigates charge exchange dynamics in MoS 2 field-effect transistors (FETs) induced by organic molecule adsorption through both experimental and theoretical studies. Adsorption of various π-conjugated molecules such as copper phthalocyanine (CuPc), cobalt phthalocyanine (CoPc), phthalocyanine (H 2 Pc), and methylene blue (MB) on the MoS 2 channel significantly modulates its electrical characteristics, resulting in distinctive changes in transfer curves ( I d –V g ) and threshold voltages ( V th ). These variations are consistent with the direction of charge transfer, as controlled by the relative energy levels of the molecular HOMO–LUMO gaps and band edges of MoS 2 . Electronic calculations based on density functional theory (DFT) confirm that electron-rich molecules act as electron acceptors, which display p -type behavior, and donor-type molecules allow n -type behavior. Theoretical calculation of bandgap and density of states analyses involving pristine and molecule-adsorbed MoS 2 further supports interfacial interactions resulting in Fermi level tuning. These findings explain the molecular-level mechanisms governing charge modulation in MoS 2 -FETs, offering valuable insights for molecular sensing and nanoelectronic applications.