Colored ink dip-pen nanolithography

Colored ink dip-pen nanolithography (DPN) is demonstrated by the direct patterning of organic dyes on substrates to generate optically active and arbitrarily shaped nanostructures with dimensions well below 200 nm in a straightforward manner. The dye nanopatterns are indeed optically active as confirmed by fluorescence emission under external pumping. The efficiency of patterning organic materials on bare and chemically modified ${\mathrm{Si/SiO}}_x$ substrates reaffirms that DPN patterning of organic molecules can be done without covalent linkages, and points to importance of noncovalent interactions in DPN. The method can be extended to direct patterning of many colored/colorless organic molecules, and should open many opportunities for miniaturized optical devices and site-specific biological staining.