Effects of ligand and chemical affinity of S and Se precursors on the shape, structure and optical properties of ternary CdS1−xSex alloy nanocrystals

•Spherical and tetrapodal CdS1-xSex NCs were synthesized by using TOP and changing x.•Structure, shape and optical properties of these NCs were controlled by varying reaction conditions.•The research results contribute to the knowledge of kinetic evolution and fabricating alloy NCs. Colloidal ternary CdS1−xSex (0 ≤ x ≤ 1) alloy semiconductor nanocrystals (NCs) with spherical and tetrapodal shapes were synthesized successfully by wet chemical method using cadmium oxide (CdO), selenium (Se), and sulfur (S) as precursors and oleic acid (OA), tri-n-octylphosphine (TOP) as ligands in 1-octadecene (ODE) solvent. For the first time, by using TOP and changing Se content, the shape of ternary CdS1−xSex alloy NCs could be tuned from spheres to tetrapods and the crystal structure could be transformed from zincblende (ZB) to wurtzite (WZ). The photoluminescence (PL) spectra of CdS1−xSex alloy NCs synthesized with and without TOP were also completely different, corresponding to one and two excitonic emission peaks. The causes of these interesting results have been discussed.