Journal Article 2D materials 2D semiconductors transition metal dichalcogenides 2D layered materials PtSe2 Schottky barrier charge injection charge transport electrochemically switchable transistors electronic structure energy-level phototuning functional devices interlayer interactions low-frequency Raman mobility molecular switches multifunctional field-effect transistors neuromorphic devices neuronal oscillations photochromic molecules photoluminescence platinum disulfide rare-earth ions rectification self-assembled monolayer single-transistor neurons substitution doping subthreshold swing top-contact bottom-gate