The controllable synthesis of semiconductor nanocrystals is important for exploiting their size-dependent properties in a variety of applications. The important wide-bandgap semiconductors ZnS and ZnSe crystallize in both the zincblende (ZB) and wurtzite (WZ) structures. While the ZB polymorphs are most stable, methods exist for synthesizing the WZ-type nanocrystals. However, because of the subtle structural differences between the ZB and WZ structures, subtle synthetic differences can favor one polymorph over the other. It is therefore challenging to predictably generate the WZ polymorphs and understand the factors that play a key role in their formation. Through careful mechanistic studies, we show that ZnO nanoparticles, which adopt the WZ structure, form as intermediates in typical reactions that generate WZ-ZnS. This implies that ZnO nanoparticles can serve as structural templates for the preferential formation of WZ-ZnS nanoparticles, and this is confirmed experimentally. Similar chemistry can be used to preferentially form WZ-ZnSe and ZB-ZnSe.

Efficient multiphoton radical generation chemistry has been developed for use in aqueous media. Through a combination of multiphoton absorption polymerisation (MAP) and optical tweezers, this chemistry has been applied to the fabrication, manipulation, and assembly of 3D polymeric and biomolecular structures. Combining MAP and optical tweezers allows for the direct assembly of 3D structures from microscale objects as well as for the realisation of structures, such as tape-like and ropelike microthreads, that can be used for unconventional microfabrication techniques including microbraiding and microweaving. These capabilities significantly expand the toolbox of methods available for the creation of functional microstructures in aqueous media.

Dip-pen nanolithography (DPN) is used to precisely position core/thick-shell ("giant") quantum dots (gQDs; ≥10 nm in diameter) exclusively on top of silicon nanodisk antennas (≈500 nm diameter pillars with a height of ≈200 nm), resulting in periodic arrays of hybrid nanostructures and demonstrating a facile integration strategy toward next-generation quantum light sources. A three-step reading-inking-writing approach is employed, where atomic force microscopy (AFM) images of the pre-patterned substrate topography are used as maps to direct accurate placement of nanocrystals. The DPN "ink" comprises gQDs suspended in a non-aqueous carrier solvent, o-dichlorobenzene. Systematic analyses of factors influencing deposition rate for this non-conventional DPN ink are described for flat substrates and used to establish the conditions required to achieve small (sub-500 nm) feature sizes, namely: dwell time, ink-substrate contact angle and ink volume. Finally, it is shown that the rate of solvent transport controls the feature size in which gQDs are found on the substrate, but also that the number and consistency of nanocrystals deposited depends on the stability of the gQD suspension. Overall, the results lay the groundwork for expanded use of nanocrystal liquid inks and DPN for fabrication of multi-component nanostructures that are challenging to create using traditional lithographic techniques.