Visible to infrared plasmonic absorption from silver nanostructures enabled by microreactor-assisted solution deposition

Abstract

The ability to control the morphology of silver films is critical since optical properties of silver films largely depend on their morphology. Due to their ability to precisely tailor the growth mechanism, vacuum-based processes have been widely used to control the morphology of silver films. In this study, we report the use of a continuous flow microreactor deposition process for the formation of silver films. Colloidal silver nanocrystals along with smaller reactive silver species are generated in the microreactor. These in situ silver reactants were delivered directly onto the glass substrate to form silver nanostructures at room temperature. The morphology of the silver nanostructure is transitioned from isolated irregular silver nanocrystals to a continuous silver nanocrystalline film as the deposition period increases. The UV-vis-NIR spectra of the resulting silver nanostructures vary correspondingly with their morphology. In particular, a broadband absorption from visible to near infrared is shown for the spectrum of the silver nanostructure close to the percolation threshold. Highly conductive silver films are also obtained as surface coverage was far beyond the percolation threshold. The utility of silver nanostructures with different morphologies is also demonstrated via surface enhanced Raman scattering (SERS) of Rhodamine B. This study demonstrates the capability of the continuous flow microreactor-assisted solution deposition process to fabricate silver nanostructures that can be useful in various applications.