A facile and low-cost synthesis of Cu2ZnSn(SxSe1−x)4 nanocrystals with tunable composition and optical band gap.

Cu 2 ZnSn(S x Se 1− x ) 4 nanocrystals have been successfully synthesized by a novel two-step route involving a solvothermal reaction of Cu 2 ZnSnSe 4 and a sulfurization post-annealing. The Se 2− is gradually replaced by the S 2− to form the CZTSSe solid solutions with a tetragonal structure when increasing the sulfurization time. The A 1 Raman modes of CZTSSe display a typical two-mode behavior, revealing that S composition plays an important role on tuning the vibrating modes. The optical band gap becomes large gradually from 0.91 to 1.30 eV with increasing S content from 0 to 0.76. CZTSSe nanocrystals derived from this method can be used as low-cost absorber layer for photovoltaic applications. [ABSTRACT FROM AUTHOR]