  Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto
substrates is a core requirement and a promising alternative to top down
lithography to create functional nanostructures and nanodevices with intriguing
optical, electrical, and catalytic features. Capillary-assisted particle
assembly (CAPA) has emerged as an attractive technique to this end, as it
allows controlled and selective assembly of a wide variety of NPs onto
predefined topographical templates using capillary forces. One critical issue
with CAPA, however, lies in its final printing step, where high printing yields
are possible only with the use of an adhesive polymer film. To address this
problem, we have developed a template dissolution interfacial patterning (TDIP)
technique to assemble and print single colloidal AuNP arrays onto various
dielectric and conductive substrates in the absence of any adhesion layer, with
printing yields higher than 98%. The TDIP approach grants direct access to the
interface between the AuNP and the target surface, enabling the use of
colloidal AuNPs as building blocks for practical applications. The versatile
applicability of TDIP is demonstrated by the creation of direct electrical
junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror
geometries for single particle molecular sensing.
