Faculté des sciences et de médecine

Tunable 2D binary colloidal alloys for soft nanotemplating

Fernández-Rodríguez, Miguel Ángel ; Elnathan, Roey ; Ditcovski, Ran ; Grillo, Fabio ; Conley, Gaurasundar Marc ; Timpu, Flavia ; Rauh, Astrid ; Geisel, Karen ; Ellenbogen, Tal ; Grange, Rachel ; Scheffold, Frank ; Karg, Matthias ; Richtering, Walter ; Voelcker, Nicolas H. ; Isa, Lucio

In: Nanoscale, 2018, vol. 10, no. 47, p. 22189–22195

The realization of non-close-packed nanoscale patterns with multiple feature sizes and length scales via colloidal self-assembly is a highly challenging task. We demonstrate here the creation of a variety of tunable particle arrays by harnessing the sequential self-assembly and deposition of two differently sized microgel particles at the fluid–fluid interface. The two-step process is... Plus

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    Summary
    The realization of non-close-packed nanoscale patterns with multiple feature sizes and length scales via colloidal self-assembly is a highly challenging task. We demonstrate here the creation of a variety of tunable particle arrays by harnessing the sequential self-assembly and deposition of two differently sized microgel particles at the fluid–fluid interface. The two-step process is essential to achieve a library of 2D binary colloidal alloys, which are kinetically inaccessible by direct co-assembly. These versatile binary patterns can be exploited for a range of end-uses. Here we show that they can for instance be transferred to silicon substrates, where they act as masks for the metal-assisted chemical etching of binary arrays of vertically aligned silicon nanowires (VA-SiNWs) with fine geometrical control. In particular, continuous binary gradients in both NW spacing and height can be achieved. Notably, these binary VA- SiNW platforms exhibit interesting anti-reflective properties in the visible range, in agreement with simulations. The proposed strategy can also be used for the precise placement of metallic nanoparticles in non-close-packed arrays. Sequential depositions of soft particles enable therefore the exploration of complex binary patterns, e.g. for the future development of substrates for biointerfaces, catalysis and controlled wetting.