Quantifying and optimizing photocurrent via optical modeling of gold nanostar-, nanorod-, and dimer-decorated MoS₂ and MoTe₂

Finite element simulations through COMSOL Multiphysics were used to optically model systems composed of Mo dichalcogenide layers (MoTe₂ and MoS₂) and Au nanoparticles (spherical dimers, nanorods, and nanostars) to understand how their fundamental material properties as well as their interactions affect the photocurrent response. The absorption cross sections of the various Au nanoparticles linearly increase with respect to their increasing dimensions, hence being ideal tunable systems for the enhancement of the electric field in the dichalcogenide layers under visible and near infrared. The photocurrent through the MoTe₂ and MoS₂ substrates was enhanced by the addition of Au nanoparticles when the plasmonic response was localized in the area of the particle in contact with the substrate. Based on these findings, the use of Au nanoparticles can greatly improve the unique photocurrent properties of Mo dichalcogenides; however, nanoparticle orientation and size must be considered to tune the enhancement at the specific wavelengths. This computational work provides useful design rules for the use of plasmonic nanomaterials in photocatalytic and photocurrent enhancement of transition metal dichalcogenides.