Synthesis of Non-Spherical CdSe Quantum Dots

We describe the synthesis of non-spherical CdSe quantum dots (QDs) through high temperature reduction of cadmium and selenium in the presence of TOP (Tri-n-octylphosphine) and TOPO (Tri-n-octylphosphine oxide). High affinity of phosphine oxide to the surface of CdSe nanocrystals usually leads to formation of spherical particles with diameter between 1.5 and 10 nm. We have developed a method that leads to the formation of non spherical shapes of nanocrystals. We performed a two-step reaction. The first step was carried at 230 degrees C for 30 minutes. The second step was an increase of the temperature from 230 degrees C to 270 degrees C and the execution of the reaction at this temperature with varying times. Results indicate that performing the reaction at 230 degrees C led to the formation of CdSe QDs shapes of spheres, hexagons, triangle, etc., and that processing at 270 degrees C led to formation of QD squares.