Controlled electrophoretic deposition of smooth and robust films of CdSe nanocrystals

Controlled purification of the CdSe nanocrystal primitive solution critically affects the electrophoretic deposition of these nanocrystals. Film morphology is optimized after two precipitation steps with no TOPO/TOP added in either step. This suggests the need to minimize impurities in the solution or to remove a controlled, small fraction of the ligands on the nanocrystal surface. The smoothness of electrophoretically deposited nanocrystal films is excellent (<3 nm rms roughness) and the appearance of particulates of nanocrystals due to homogeneous nucleation is minimized, even during patterned deposition. Treating the films with cross-linker molecules makes the electrophoretically deposited films very resistant to dissolution and flaking in many solvents.