Facile preparation of metal telluride nanocrystals using di-n-octylphosphine oxide (DOPO) as an air-stable and less toxic alternative to the common tri-alkylphosphines

Abstract

In this paper, we have developed a “green” method for the synthesis of metal telluride nanocrystals. In this method, di-n-octylphosphine oxide (DOPO) has been used to disperse Te and form Te–DOPO precursor. This new Te precursor was found to be highly reactive and suitable for the synthesis of metal telluride nanocrystals in various monodispersity, size, and shape. Dot-/tetrapod-shaped CdTe, dot-shaped ZnTe, dot-/cubic-shaped PbTe, dot-/rod-shaped Ag₂Te, cubic-shaped Cu_2−xTe, ternary alloyed CuInTe₂, and quaternary alloyed Cu₂ZnSnTe₄ semiconductor nanocrystals all have been well-controlled synthesized. The photoluminescence emission of as-synthesized CdTe nanocrystals covered a wide range (570–735 nm) and the quality of as-synthesized metal telluride nanocrystals were reached or exceed the level compared with the traditional method using phosphine–Te precursor. The possible dissolving molecular mechanism of Te in DOPO in this synthesis was specially studied and illustrated that intramolecular proton transfer from the phosphorus (formation of DOPO–Te complex) was essential in the synthesis of metal telluride nanocrystals. This method provided a greener and less expensive route to large-scale synthesis of all kinds of high quality metal telluride nanocrystals.