Reaction Tailoring for Synthesis of Phase‐Pure Nanocrystals of AgInSe2, Cu3SbSe3 and CuSbSe2

Present article highlights synthesis of phase pure I, III, VI2 and I, V, VI2 ternary selenides nanocrystals (NCs) using oleic acid and oleyl amine capping agents. The synthesis of AgInSe2 (AISe), Cu3SbSe3 and CuSbSe2 (CSSe) NCs was executed by employing cyclohexeno‐1,2,3‐selenadiazole (SDZ) as Se precursor. The current study is the first report describing use of thermally labile organoselenium compound for the synthesis of such technologically important ternary selenide NCs. Systematic study of the formation of AISe and CSSe NCs at different reaction time is carried out in order to confirm phase purity and stoichiometry. The spherical, stoichiometric and NIR active semiconductors showed formation of orthorhombic crystal structure as confirmed from XRD analysis. It was observed that formation of phase pure AISe NCs requires 5 hours (h) of constant heating at about 220οC irrespective of the capping agents however, CuSbSe2 was obtained within an hour in presence of oleyl amine at same reaction temperature. Nanocrystals were characterized by different analytical tools such as UV‐Visible spectroscopy, FTIR, XRD, SEM/EDS, TEM, particle size and XPS analysis. Based on the results, possible chemical reaction pathway for ternary chalcogenide is presented. First ever report on use of cyclohexeno‐1,2,3‐selenadiazole as source of Se for the synthesis of AgInSe2, Cu3SbSe3 and CuSbSe2 nanocrystals via chemical reaction tailoring. Formation of phase pure AISe and CSSe NCs proceeds via step‐wise growth with initial formation of Ag2Se and Cu2‐xSe followed by in‐situ insertion of In3+ or Sb3+ ions in their lattice. Phase purity and transformation is found to be time dependent.