Engineering metal-dielectric nanostructures involving silver decorated Halloysite for augmented surface plasmon-coupled directional emission

Abstract Metal-dielectric hybrid nanostructures have recently drawn interest because of their direct coupling between metal surface plasmon resonance and dielectric electric dipoles leading to hybridized modes resulting in low losses and high field enhancements. Surface plasmon-coupled emission is a similar phenomenon that exploits the surface plasmon polaritons generated at the junction of dielectric and metal planar boundary. In this regard, we propose and demonstrate the use of dielectric nanotubes – Halloysite (HS) as spacer materials on metallic silver thin film. In this work, we selectively modified HS by acid or base treatment. Further they were loaded with silver nanoparticles (AgNPs) by solution deposition (in-situ method), thereby creating a metal-dielectric hybrid material. Selective acid and base treatment of HS nanotubes affected the surface charge distribution and aggregation of the nanotubes. Better dispersion ability and higher electronegativity behaviour was observed in base-treated HS that aided in higher loading of AgNPs. Enhanced interparticle plasmon coupling and better transmission of plasmon mediating energy was observed in base-treated HS-Ag that augmented dipole emission. The enhanced plasmon-coupled emission of HS-Ag nanostructures were also explored using a low-cost mobile phone as a detector to simplify the process of fluorescence detection.