Synthesis of silver nanoplate based two-dimension plasmonic platform from 25 nm to 40 μm: growth mechanism and optical characteristic investigation in situ

Abstract

Silver nanoplates (SNPs) with single-crystalline structures are highly expected building blocks for the construction of a two-dimensional (2D) plasmonic platform regarded as an advanced tool for the development of subwavelength light management technologies. One barrier for SNP fabrication is how to achieve structures with a lateral size large enough and a thickness thin enough for large-scale light manipulation. Here we propose a multistep chemical synthesis strategy which overcomes this bottleneck and greatly enriches the morphological features of SNPs by deliberately enhancing the behaviors of selective etching and self-assembly during a dynamic crystal growth process. Growth mechanisms were comprehensively studied with the help of real-time microscopic monitoring in situ. Three types of SNP with different morphology features including 100% yield small SNPs with a controllable surface plasmon resonance band, large SNPs decorated with hot spots and giant SNPs (up to ∼40 μm) with an ultra-high aspect ratio (over 1000 : 1) and ultrathin thickness were successfully achieved. Using such an engineered 2D platform combining waveguiding and nanoantenna effects, we demonstrated that plasmon enhanced optical information in deep subwavelength volumes can be remotely excited, transferred and scattered into free space directionally. Subwavelength light transmission with multiple excitation wavelengths and tunable one-dimensional (1D) and zero-dimensional (0D) light scattering as well as photoluminescence enhancement of light emitters was exhibited. It represents significant advances in in situ light manipulation which are useful in various applications for nanophotonics and remote sensing.