Selective Electrophoretic Deposition of CdSe Nanoplatelets

In the fields of nanoparticle synthesis and application, the control of the particle size, shape and composition is crucial. The tuning of these different parameters can be performed during the synthesis, but often, additional selection steps to improve the purity of a given nanoparticles’ population are necessary. These additional postsynthesis selection steps, that can include size selective precipitation, ultracentrifugation or liquid chromatography, are usually long and not well suited for a large quantity of materials. Here, we demonstrate that electrophoresis performed directly in organic solvent can be used to select and/or separate semiconductor nanoparticles according to their size and shape. In particular, we show that 2D nanoplatelets (NPL) can be very efficiently separated from spherical nanoparticles as the side product obtained during the NPL synthesis. The selectivity of the electrophoretic deposition we observe is mostly related to the nanoparticle surface charge. We show that centimeter scale, uniform film of nanoplatelets can be obtained even on nonconducting substrates. Compared to other methods this technique is fast, easy to implement and scalable, and should find various uses both in the fields of the nanoparticle synthesis and their applications.