Accurate Prediction of the Color Properties of Au and Ag Nanoparticle Composites

This work is motivated by the possibility of generating films with tunable color by means of external stimuli. We study the color changes produced by varying the geometrical parameters and/or the materials involved in structures comprising regular arrangements of silver and/or gold nanospheres. Particular attention is paid to an accurate description of the dielectric function of the metallic nanoparticles within the visible spectrum, including size corrections. The Korringa-Kohn-Rostoker method is used to calculate the optical response of the investigated structures and the obtained spectra are then used to find the colors produced. The analysis of hybrid systems shows their potential to enlarge the achievable color palette. The effect of stretching a regular structure on the obtained color is also analyzed, which evidences the possibility of tuning the color by mechanical efforts. This study shows that a wide color palette can be obtained by changing the different parameters of the structure, and therefore it can be used as a model to manufacture tunable color films.