Patterning of quantum dots by dip-pen and polymer pen nanolithography

We present a direct way of patterning CdSe/ZnS quantum dots by dip-pen nanolithography and polymer pen lithography. Mixtures of cholesterol and phospholipid 1,2-dioleoyl-sn-glycero-3 phosphocholine serve as biocompatible carrier inks to facilitate the transfer of quantum dots from the tips to the surface during lithography. While dip-pen nanolithography of quantum dots can be used to achieve higher resolution and smaller pattern features (approximately 1 μm), polymer pen lithography is able to address intermediate pattern scales in the low micrometre range. This allows us to combine the advantages of micro contact printing in large area and massive parallel patterning, with the added flexibility in pattern design inherent in the DPN technique.