Multiple plasmon couplings in 3D hybrid Au-nanoparticles- decorated Ag nanocone arrays boosting highly sensitive surface enhanced Raman scattering

Plasmon coupling is an essential strategy to realize strong local electromagnetic (EM) field which is crucial for high-performance plasmonic devices. In this work, multiple plasmon couplings are demonstrated in three-dimensional (3D) hybrid plasmonic systems composed of polydimethylsiloxane-supported ordered silver nanocone (AgNC) arrays decorated with high-density gold nanoparticles (AuNPs) which are fabricated by a template-assisted physical vapor deposition process. Strong interparticle coupling, particle-film coupling, inter-cone coupling, and particle-cone coupling are revealed by numerical simulations in such composite nanostructures, which produce intense and high-density EM hot spots, boosting highly sensitive and reproducible surface enhanced Raman scattering (SERS) detection with an enhancement factor of ~ 1.74 × 10⁸. Furthermore, a linear correlation between logarithmic Raman intensity and logarithmic concentration of probe molecules is observed in a large concentration range. These results offer new ideas to develop novel plasmonic devices, and provide alternative strategy to realize flexible and high-performance SERS sensors for trace molecule detection and quantitative analysis.