Configurable plasmonic substrates from heat-driven imprint-transferred Ag nanopatterns for enhanced photoluminescence

Abstract

Despite substantial progress in metal nanopatterning, fabricating ultra-large-area plasmonic substrates with well-defined and well-controlled nanopatterned arrays remains a major technological challenge. Here, we describe a novel facile technology (i.e., configurable metal nanoimprint transfer based on geometric reconfiguration during thermal annealing) to fabricate ultra-large-area tunable plasmonic substrates. The simultaneous transfer and imprint of the metal layers from the patterned mold surface results in metal nanopatterns embedded in a partially cured photoresist, the shape of which can be modified systematically by optimized heat treatments. The plasmonic properties of the metal nanopattern array could be precisely tuned through the heat-driven shape reconfiguration of metal patterns. The shape transformation leads to sharp and blue-shifted extinction spectra and unusual strong excitation of the transverse mode of metal nanopatterns. Coarse tuning of the plasmon resonance wavelength is achieved by varying the diameter of the nanopatterned features, and fine tuning is accomplished by reconfiguring the geometry of the nanopatterned features via thermal annealing. Only three master patterns are required to cover the wavelength range 535–837 nm. By applying the plasmon substrates to photoluminescence (PL) measurements, an enhancement in the green photoluminescence (PL) intensity of a factor more than 9.4 is achieved due to the improved matching between the wavelengths for PL emission and plasmon resonance. The fabrication strategy described here enables us to achieve various plasmonic properties using a single master pattern, which provides both tailorable plasmonic properties and remarkable process flexibility.