Chemical synthesis, characterization and theoretical investigations of stannite phase CuZn2AlS4 nanocrystals

Abstract

Stannite phase CuZn₂AlS₄ (CZAS) nanocrystals have been grown for the first time using hot injection and hydrothermal processes. As-synthesized nanocrystals in the shape of nanowires (from a hot injection process) and nanoplates (from a hydrothermal process) show band gaps of 1.64 eV and 1.69 eV, respectively, which is attractive for use as solar cell absorber materials. From first principles study, we find that CZAS exhibits direct band characteristics with a high absorption coefficient of >10⁴ cm⁻¹. Based on energy considerations the stannite structure is found to be more stable than the kesterite, wurtzite, orthorhombic and zinc blende type structures. The total and partial density of states (DOSs) indicate that hybridization between Zn-s and S-p like bands occurs near the Fermi level.