In situ ligand exchange of thiol-capped CuInS2/ZnS quantum dots at growth stage without affecting luminescent characteristics

Abstract

An aliphatic thiol ligand of CuInS2/ZnS core/shell quantum dots is replaced with a hydroxyl-terminated thiol ligand by utilizing 'on-off state' of ligands during growth stage of the quantum dots. After the ligand-exchange, negligible differences were observed on both photoluminescence spectrum and luminescent quantum efficiency. The reason for the high retention of luminescent efficiency comes from no local agglomeration and no surface deterioration of QDs. It is also observed that 70% of initial ligands are exchanged by the replacing ligand, determined by FT-IR and H-1 NMR. The proposed method provides the quantum dots with an excellent dispersibility in polar solvents, supported by identical luminescence decay characteristics of the QDs. (C) 2011 Elsevier Inc. All rights reserved.