Light-Responsive Plasmonic Arrays Consisting of Silver Nanocubes and a Photoisomerizable Matrix

• Published in: ACS applied materials & interfaces 2015-03, Vol.7 (8), p.4902-4912
• Main Authors: Ledin, Petr A, Russell, Michael, Geldmeier, Jeffrey A, Tkachenko, Ihor M, Mahmoud, Mahmoud A, Shevchenko, Valery, El-Sayed, Mostafa A, Tsukruk, Vladimir V
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am508993z

We report on the synthesis of novel branched organic–inorganic azo-polyhedral oligomeric silsesquioxane (POSS) conjugates (Azo-POSS) and their use as a stable active medium to induce reversible plasmonic modulations of embedded metal nanostructures. A dense monolayer of silver nanocubes was deposited on a quartz substrate using the Langmuir–Blodgett technique and subsequently coated with an ultrathin Azo-POSS layer. The reversible light-induced photoisomerization between the trans and cis states of the azobenzene-terminated branched POSS material results in significant changes in the refractive index (up to 0.17) at a wavelength of 380 nm. We observed that the pronounced and reversible change in the surrounding refractive index results in a corresponding hypsochromic plasmonic shift of 6 nm in the plasmonic band of the embedded silver nanocubes. The reversible tuning of the plasmonic modes of noble-metal nanostructures using a variable-refractive-index medium opens up the possibility of fabricating photoactive, hybrid, ultrathin coatings with robust, real-time, photoinitiated responses for prospective applications in photoactive materials that can be reversibly tuned by light illumination.