Near-field electromagnetic effects in light-assisted growth of chalcogenide nanostructures

Light-assisted photoelectrodeposition allows the growth of highly anisotropic chalcogenide nanostructures, providing a promising strategy for precise control over nanoscale morphology with potential applications in optoelectronic and energy conversion devices. Despite extensive experimental and simulation studies, the optical contribution to morphology selection has not been fully isolated from electrochemical, mass transport, and reaction kinetics. Here, we focus exclusively on the optical component by performing finite-element electromagnetic simulations solving Maxwell's equations to analyze the near-field response of representative chalcogenide materials (tellurium and selenium). Idealized hemispherical, hemiellipsoidal, and nanorod-like geometries were employed to capture experimentally observed growth morphologies, and the effect of neighboring nanostructures on near-field interactions was systematically examined. The simulations reveal that near-field localization and spatial redistribution depend on the interplay between geometry, the optical constants of the material, interparticle coupling, and the polarization-dependent excitation of electromagnetic modes, suggesting the emergence of morphology- and material-specific optical responses that can bias directional growth under illumination. These results offer a quantitative perspective for understanding how optical near-field, including their polarization dependence, may contribute to directional morphology during light-assisted growth, providing insight into the formation of nanostructured materials under controlled optical excitation.