Kahn, AntoineHaverstick, Quinn L.2025-08-122025-08-122025-04-14https://theses-dissertations.princeton.edu/handle/88435/dsp01q237hw400Layered transition metal dichalcogenides are an emerging class of atomically-thin, layered materials for use in solar cells, transistors, LEDs, and other optoelectronic devices. These materials are flexible and durable, with bandgaps that shift from indirect as a bulk film to direct as a monolayer, allowing for finely tunable devices. Two of these materials, WSe2 and WS2, have bandgaps around 2 eV, making them more versatile than other 2D materials such as graphene, which lacks a bandgap. This project focused on mono- and multilayer WSe2 and WS2 films, and determined their conductivity, established the position of the Fermi level, and introduced [RuCp*Mes]2, an air stable dimer, as an n-type dopant to determine shifts in Fermi level and changes in conductivity with doping. The introduction of the Ru dimer increased the conductivity of monolayer WSe2 films by 3 orders of magnitude and increased the conductivity of monolayer WS2 films by 4 orders of magnitude, indicating successful doping. The Fermi level of undoped monolayer WSe2 was found to be close to the conduction band minimum and the Fermi level of monolayer WS2 was found to be slightly below the conduction band minimum. After doping with [RuCp*Mes]2, the Fermi level of monolayer WSe2 did not shift significantly due to its proximity to the valence band minimum, but the Fermi level of monolayer WS2 shifted upward. Due to charges on the surface, the work function of both monolayer films decreased with doping, with a greater change in monolayer WS2.en-USPrinceton University Senior Theses