Surface roughness boosts the SERS performance of imprinted plasmonic architectures

Abstract

The large-area low-cost rough plasmonic crystal (r-PC) SERS substrates introduced herein outperform smooth counterparts and rough films both in the magnitude of the enhancement factor (EF) and in the number of vibrational peaks displayed in the Raman spectrum. In r-PCs, the photonic modes launched by the lattice excite more intense and abundant localized resonances in the sharp edges and gaps present in the rough metal surface. 2D r-PCs are fabricated by nanoimprinting a nanocrystalline titania paste followed by silver coating, resulting in a highly reproducible rough photonic architecture. The SERS performance of these architectures is tested via the detection of two molecules: benzenethiol and 4-mercaptopyridine. The resulting EF values exceed 10⁷ in the case of benzenethiol and 10¹⁰ when 4-mercaptopyridine is used. The simple fabrication strategy and the high performance exhibited by these nanoimprinted substrates make rough plasmonic architectures one of the most promising candidates for inexpensive and efficient mass-produced SERS substrates.