Self-assembly of Large-scale Two-dimensional Plasmonic Superlattices Based on Single-Crystal Au Nanospheres and the FDTD Simulation of Its Optical Properties

Large-scale ordered two-dimensional (2D) superlattices at oil/water interface were fabricated using single-crystal Au nanospheres (NSs) with different diameters as building blocks. A “drain-to-deposit” strategy was used to successfully transfer the ordered superlattices onto silicon wafer. Due to the ultra-smooth and highly spherical morphology of the monodisperse Au NSs, the UV-Vis extinction spectra of individual Au nanosphere (NS) obtained from theoretical calculations by finite-difference time-domain (FDTD) method could match well with the experimental test results. Moreover, the extinction spectra of the 2D superlattice based on the different diameters of Au NSs were also measured and calculated. Additionally, with R6G as probe molecules, the surface-enhanced Raman spectroscopy (SERS) performances of the prepared superlattices were evaluated. Through investigating the electromagnetic (EM) field distribution simulation results of 2D superlattices of Au NSs with different diameters, the two results reveal rather consistently. The large-scale 2D plasmonic superlattices possess precise and tunable localized surface plasmon resonance (LSPR) property, which enables them to have great application prospect in solar cells, SERS detection, and other fields.