Synthesis and surface composition study of CdSe nanoclusters prepared using solvent systems containing primary, secondary, and tertiary amines

A series of primary, secondary, and tertiary amines have been examined as cosolvents with trioctylphosphine oxide (TOPO) for the synthesis of CdSe nanoclusters. Syntheses were conducted in 66 mol % hexadecylamine (HDA), dodecylamine (DDA), dioctylamine (DOA), or trioctylamine (TOA) in TOPO and the growth rates and size distributions of the resulting products compared with those obtained from the same reaction conducted in pure TOPO. DOA was found to advantageously slow the growth rate of the nanoclusters and produce material with a narrow size distribution and moderate fluorescence quantum yield. Thermal gravimetric analysis (TGA) of the products has been used to quantify the ratio of TOPO to amine on the nanocluster surface and shows that the primary amines attain the highest packing densities. STM imaging of materials synthesized in the presence of HDA or DOA and then self-assembled on nonanedithiol SAMs shows improved surface stability for the DOA synthesized products.