A high efficient photoluminescence Zn–Cu–In–S/ZnS quantum dots with long lifetime

Abstract

Highly Cu-rich copper indium sulfide (CuInS2, CIS) quantum dots were synthesized utilizing copper chloride (CuCl) and indium acetate (In(Ac)3) as metal cation precursors, combined with n-dodecanethiol (DDT) as a coordinating sulfur source and solvent. With excess of In(Ac)3, i.e. with Cu/In ratios of 1/4, together with Zn2+ ions post-treatment, a relatively high photoluminescence quantum yield (QY) of ∼73% with long average lifetime of ∼359ns has been obtained, which is proposed to be attributed to the Cu-rich defect states in the CIS nanocrystals (NCs) nuclei. Meanwhile, the formation of In-rich CIS–ZnS alloy, i.e. Zn–Cu–In–S (ZCIS) with high density of Cu vacancies, combined with the surface passivation of ZnS overlay resulted in a high QY. Finally, the formation mechanism of the ZCIS/ZnS with Cu-rich nuclei has been proposed.