Optical characterizations of silver nanoprisms embedded in polymer thin film layers

Abstract

The study of the light matter interaction phenomena is driven by the use of metallic nanoparticles. In this context, our work is focused on optical characterization and modeling of polymer thin films layers with inclusions of previously chemically synthesized nanoparticles, resulting in tunable optical properties in the visible wavelength range. The nanoprisms are synthesized by a two-step seed based chemical synthesis in mild conditions, i.e. in water and at room temperature. The plasmonic resonance peaks of the resulting colloidal solutions range from 360 to 1300 nm. Poly vinyl pyrrolidone polymer matrix is chosen for its non-absorbing optical properties and NP-stabilizing properties. Knowledge on the size of the NPs embedded in the spin coated layers is obtained by transmission electron microscopy imaging. The optical properties measurements include spectrophotometry and spectroscopic ellipsometry to get the reflectance, the transmittance, the absorptance and the optical indices n and k of the heterogeneous layers. A redshift in absorption is measured between the colloidal solutions and the deposited layers. FDTD simulations allow calculation of far and near field properties. The visualization of the NP interactions and the electric field enhancement, on and around the NPs, are studied to improve the understanding of the far field properties.