Plasmonic three-dimensional dimpled array from highly ordered self-assembled liquid crystal defects

Abstract

Various lithography techniques have been developed to fabricate well-defined and small feature sized metallic patterned structures, to utilize the plasmonic property or hot spot effect. In this study, a dimple-shaped plasmonic array was prepared from a self-assembled liquid crystal (LC) defect structure, the so-called toric focal conic domains (TFCDs). This uniform and well-ordered micro-dimple array was replicated by a UV-curable photopolymer (NOA63) and polydimethylsiloxane (PDMS) which resulted in conical and dimpled arrays on the polymer molds, respectively. A thin gold (Au) layer (40 nm) was deposited on the polymer replica molds (NOA63 and PDMS) and the Au dimpled array showed a good field enhancement phenomenon from QD fluorescence signal observation. Also, FDTD simulation analysis was carried out to support electromagnetic field behavior near each geometry (conical and dimpled structures). The dimple-shaped TFCD array is advantageous as a plasmonic template due to the geometrical effect. Also this self-assembly approach is a cost-effective, fast, and simple process. Furthermore, the dimpled configuration has the potential to be applied for collecting nano-or microsized materials, which might be useful for enhanced plasmonic sensing in the biological and chemical field of studies.