Tunable Electronic and Optoelectronic Properties of MoS ₂ Through Molecular Coverage‐Controlled Polyoxometalate Doping

ABSTRACT We investigated the functionalization of pristine and post‐deposition‐annealed atomic layer deposition (ALD)‐grown MoS 2 films on silicon wafers with the polyoxometalate (POM) ( n Bu 4 N) 3 [HV 12 O 32 Cl(DyPc)] (referred to as V 12 ‐ DyPc ) and its impact on the optical and electronic properties of 2D semiconductor layers. Thin‐film analysis confirms the formation of high‐quality, polycrystalline MoS 2 after annealing. The deposition of V 12 ‐ DyPc induces a concentration‐dependent reduction in A exciton emission and the emergence of negatively charged trion (A – ) photoluminescence (PL), evidencing systematic charge transfer. Studies on thinner MoS 2 layers grown by metal‐organic chemical vapor deposition (MOCVD) corroborate this effect. Short‐range surface ordering of POMs is detected on pristine, amorphous MoS 2 . Notably, V 12 ‐ DyPc exhibits identical multilevel switching behavior on both amorphous and polycrystalline, annealed MoS 2 . On MoS 2 , V 12 ‐ DyPc shows a significantly reduced lateral electronic density distribution (3 nm compared to 7 nm on highly oriented pyrolytic graphite (HOPG)) and a more positive first reduction potential (3.1 V vs. 2.1 V, respectively). These changes are due to the substantially increased surface roughness of MoS 2 relative to the atomically flat HOPG substrate, and to the impact of a modified chemical environment on MoS 2 . Density functional theory (DFT) and molecular mechanics simulations reveal face‐on bonding geometries, altered redox energetics, and substrate‐dependent shifts in electronic states.