Proceedings of nanoGe September Meeting 2017 (NFM17)
Publication date: 20th June 2016
Colloidal CdSe nanoplatelets (NPLs), which are also known as colloidal quantum wells, have recently received much attention due to their atomic precession of thickness, outstanding optical properties such as tunable, very sharp (full-width at half-maximum ~8 nm) emission, faster carrier recombination than that of quantum dots and rods, and low-threshold lasing properties and higher stability in ambient atmosphere. Here we demonstrate a simple strategy to induce the self-assembly of two different type of CdSe NPLs into micron-long threads by adding small amounts of oleic acid (OA) to a NPL dispersion, followed by controlled drying. These structures are flexible since they are composed of a single platelet in their lateral dimension and continuously break and reform in solution similar to ‘living polymers’ formed by some surfactants. Optical fluorescence microscopy, transmission electron microscopy provide detailed structural characterization and show that threads can be composed by highly organized 100 to 1000 NPLs.1 By changing the shape of the NPLs we 1st time produce helicoidal chiral ribbon with micrometers length and constant pitch of ~400 nm by assembly of NPLs under the effect of the addition of excess ligand. We demonstrated that the chirality originates from surface strain caused by the ligand since isolated NPLs in dilute solution undergo a transition from a flat to twisted shape as ligand coverage increases. When the NPLs are closely stacked within ribbons, the individual twist propagates over the whole ribbon length and forming helicoidal chiral ribbon.
1. S. Jana, P. Davidson, B. Ab¦cassis. Angew.Chem. Int.Ed. 2016, 55,9371–9374
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