Nanoimprinting Sub-100 nm Features in a Photovoltaic Nanocomposite using Durable Bulk Metallic Glass Molds

The use of bulk metallic glass (BMG) for the nanoimprint of high-aspect-ratio (>3) features into functional polymers is investigated. To accomplish this, the most critical aspect is the successful demolding of the imprinted polymer. By fluorosilane functionalization of the BMG surface and optimization of processing temperature, high aspect pore features down to 45 nm diameters are introduced into the surface of two organic photovoltaic systems: poly(3-hexylthiophene-2,5-diyl) (P3HT) and 1:1 mixtures of P3HT with Phenyl-C61-butyric acid methyl ester (PCBM). The crystallinity of P3HT demands higher forming temperatures and pressures that are difficult to obtain with conventional soft nanoimprint lithography molds. The ability to accommodate a wide range of processing conditions and the low cost of fabricating molds with nanometer-scale features point to the large potential of nanotextured BMGs as an economical and scalable imprint material for high-resolution applications.