Molecular to Mesoscopic Design of Novel Plasmonic Materials—Combining First-Principles Approach with Electromagnetic Modelling

To date, due to the rapid progress in science and technology, the efforts for reaching new plasmonic materials are extensively growing. Although the most often used noble metals, such as Au and Ag, demonstrate a strong optical response in plasmonics and metamaterials, some of their inherent features make them less suitable for real-world applications. In this work, we aim to seek new alternative plasmonic materials by proposing a novel and reliable method via manipulating the characteristic response of candidate compounds such as Al/Ga doped Zinc Oxide (A/GZO), ZrN, TiN and Silicon allotropes. This method merges two powerful computational approaches, namely, density functional theory (DFT) and electromagnetic (EM) simulations by the finite-element method (FEM) and more rigorous methods (e.g. TMM, RCWA). We first perform a series of DFT calculations, including the structural relaxation of plasmonic material candidates, to find the crystal structure with minimum energy, for different exchange-correlation functionals such as GGA, LDA. In a second step, we analyse the simulated material’s electronic and optical properties to illustrate potential metallic behaviour, from the viewpoint of material science, via electronic density of states (DOS), band structure and optical dispersion functions (real and imaginary parts). To evaluate the found material’s performance in a semi-real plasmonic system, we subsequently extract the optical dispersion parameters, such as refractive index data as well as Drude-Lorentz parameters of complex dielectric permittivity from our calculated DFT. We finally feed the generated optical dispersion data into an EM-solver for optical simulations of any desired optical system and investigate its efficiency for suitability in plasmonic applications. Our method comprises the possibility for verification with experimental data on each level. From there on, we can optimize digitally the molecular structure, paving the way to predict the proposed compounds’ plasmonic functionality, overcoming the persistent hurdles introduced by pure experimental works.