Electrostatically Driven Vertical Combinatorial Patterning of Colloidal Nano-Objects

The hierarchically directed assembly of multiple types of colloidal nano-objects on surfaces is of interest for developing disruptive applications combining their original properties. We propose herein a versatile, electrostatically driven strategy to arrange various kinds of colloids vertically in the shape of 3D micropatterns by nanoxerography. We made the proof of concept of this vertical combinatorial nano-object patterning using two types of photoluminescent CdSe(S)/CdZnS core/shell nanoplatelets emitting in the red and green wavelengths as model colloidal nanoparticles. The key experimental parameters were investigated to tune the thickness of each independent level of nanoplatelets within the vertical stack. We finally applied such a concept to make dual-colored nanoplatelet patterns. Interestingly, we proved numerically that the relatively high index of the nanoplatelet level is responsible for the partially directed emissions observed in photoluminescence experiments.