Solution-based straight and branched CdSe nanowires

Confined straight and branched CdSe nanowires (NWs) are synthesized using a solution-based approach which leverages advances in the synthesis of colloidal CdSe quantum dots (QDs) with incipient approaches for the seeded (solution) synthesis of semiconductor NWs. The resulting straight and branched NWs have typical diameters below 10 nm with accompanying lengths between 1 and 10 mum. In the case of branched NWs, tripod, v-shaped, and y-shaped morphologies are observed. Variations in this preparation lead to higher order structures with multiple arms. The branching transition is discussed, and a possible mechanism based upon geminate NW nucleation is proposed. Such solution-grown straight, branched, and higher-order NWs exhibit potentially interesting optical, electrical, and transport properties due to their narrow radii below the corresponding bulk exciton Bohr radius of CdSe. Furthermore, this transition from straight to branched morphologies opens up avenues for investigating not only size- but also shape-dependent optical/electrical properties of one-dimensional (1D) and quasi-1D materials.