Background: In the last decades, the enormous interest in 2/3D nanocrystal (NC) architectures boosted the development of many and diverse techniques which allowed to precisely positioning the nanoparticles on substrates. The tremendous importance of such NC organizations is due to the novel collective properties arising from inter-particle interactions that emerge in these articial materials, with promising application in opto-electronics, photonics and biomedicines.
Methods: Properly synthesized luminescent colloidal CdSe@ZnS NCs, coated by a silica shell, have been functionalized introducing specific chargeable moieties at their surface. At the same time, a patterned substrate has been fabricated by NanoImprint Lithography (NIL) on a polymer film deposited on a silicon substrate, resulting in polymeric structures alternating to bare silicon regions. Such “polymer-free” area have been further functionalized with charged bifunctional molecules to form a self-assembled monolayer (SAM), able to attract, by electrostatic interactions, the silanized NCs.
Results: The directed self-assembly of the luminescent silica coated CdSe@ZnS NCs, onto a patterned substrate, has been shown. The functionalized NCs are organized onto appropriately functionalized and patterned substrates, by means of electrostatic interactions. The driven assembly of the NCs allows to obtain the formation of geometrically defined luminescent patterns on silicon substrates.
Conclusion: The presented procedure ingeniously combine a top-down fabrication technique, NIL, with a bottom-up electrostatic self-assembly approach, achieving a versatile tool for fabricating original functional superstructures. Importantly, the surface functionalization, both of NCs and template substrate, has been shown to play a crucial role in the fabrication of the NC patterns, thus providing promptly integrable and versatile functional platforms, potentially useful for photonic and biosensing applications.