A comprehensive analysis of hexagonal nanoprism for broad band tunability.

In the present paper, we have explored the broadband plasmonic effect in hexagonal nanoprism (HNP) in context of cost effective thin multi-junction photovoltaic devices for broad spectral response along with the surface enhanced Raman scattering (SERS) application. Optical properties have been investigated as a function of explicit sets of realistic parameters in terms of hexagonal side (10-50 nm), prism height (20-80 nm), surrounding environment (SiO2, TiO2 and Si) and material composition (Au, Ag and Al) by using discrete dipole approximation. Structural anisotropy allows us to observe in plane and out of plane resonances, which is quite interesting. The presence of in-plane dipole, in-plane quadrupole, out-of-plane dipole and out-of-plane quadrupole resonance peak at 1375 nm, 1057 nm, ~ 832 nm and ~ 621 nm respectively affirms the broadband tunability for Au HNP embedded in Si matrix with hexagonal side and prism height both 50 nm. Our simulations open a wide range of opportunities for a variety of applications such as, biological and communication windows-matched plasmonic resonance that shall be helpful for photothermal therapy and detection enhancement of NIR photodetectors. In addition, prodigious value of field intensity of each excitation mode provides selective tunability for SERS. A remarkable electric field enhancement up to 159-fold in TiO2, suggesting strong potential for photocatalysis and SERS applications.