CuInS2/ZnS core/shell quantum dots by cation exchange and their blue-shifted photoluminescence

Abstract

Highly luminescent CuInS₂/ZnS (CIS/ZnS) core/shell quantum dots with a quantum yield of 65% were synthesized by a cation exchange reaction. Similar sized CIS cores and CIS/ZnS core/shells, which were confirmed by TEM, showed that cation exchange occurred inside the core, which reduced the core size and increased the blue-shift in their emission. ICP revealed the CIS cores to have a gradient composition that is richer in indium close to the surface of the core, which explains the broad emission spectrum. This cation exchange reaction could be applied to AgInS₂ (AIS) QDs, which showed a blue shift of 70 nm in the emission spectrum. The PXRD pattern also showed a peak shift as evidence of a core/shell structure.