Synthesis of Water-Soluble CuInS2 Quantum Dots by a Hydrothermal Method and Their Optical Properties

Water-soluble CuInS2 (CIS) quantum dots (QDs) were hydrothermally prepared in the presence of N-acetyl-l-cysteine (NAC) as a stabilizer, and the optimal hydrothermal synthetic conditions for NAC-capped CIS QDs were investigated. The photoluminescence (PL) quantum yield (QY) of the CIS QDs synthesized under optimal conditions was 4%, which was comparable with the highest QY reported for water-soluble CIS core QDs. The introduction of a ZnS shell produced CIS/ZnS core/shell QDs and further increased the PL QY to 30%. Furthermore, bilayer structures consisting of Au nanoparticles and CIS/ZnS QDs were fabricated using a layer-by-layer method to enhance the PL of the CIS/ZnS QDs on the basis of the localized surface plasmon resonance of Au nanoparticles.