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

Abstract

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.

Origin of photoluminescence of water-soluble CuInS2 quantum dots prepared via a hydrothermal method

“…In this study, CIS QDs were prepared using hydrothermal method following the procedure described in ref. 32 . First, a precursor solution was prepared by mixing CuCl 2 ·2H 2 O, InCl 3 ·4H 2 O, and Na 2 S·9H 2 O as the Cu, In, and S ion sources, respectively, with the ligand N -acetyl- l -cysteine (NAC) in ultrapure water as a solvent with a molar ratio of 1 : 2 : 2.4 : 18.…”

“…Therefore, in our previous study, we directly synthesized water-soluble CIS QDs and CIS/ZnS core/shell QDs using the hydrothermal method. 31,32 We optimized the synthesis conditions such as the Cu:In:S ratio, reaction temperature, and reaction time and successfully fabricated CIS QDs exhibiting a PLQY of 4%. Furthermore, an increase of 30% was observed in the PLQY of the synthesized CIS/ZnS core/shell QDs.…”

“…Furthermore, an increase of 30% was observed in the PLQY of the synthesized CIS/ZnS core/shell QDs. 32 Majority of the previously reported studies on CIS QDs revolved around the synthesis of CIS QDs with high PL efficiency; however, recently, several studies have been performed to investigate the origin of the PL of CIS QDs. Zhong et al reported that the PL characteristics of CIS QDs originates from "donor-acceptor pair" (DAP) emission, based on experimental time-resolved PL spectroscopy and PL decay prole results.…”

“…Furthermore, an increase of 30% was observed in the PLQY of the synthesized CIS/ZnS core/shell QDs. 32 …”

Nanoarchitectonics for Hierarchical Fullerene Nanomaterials

“…Accordingly, nanoscale materials sciences have been paid much attention. Nanoscale materials in various dimensions such as quantum dots [ 31 , 32 , 33 ], nanoparticles [ 34 , 35 , 36 ], nanocrystals [ 37 , 38 , 39 ], nanotubes [ 40 , 41 , 42 ], nanorods/nanowires [ 42 , 43 , 44 , 45 ], nanosheets [ 46 , 47 , 48 ], graphene [ 49 , 50 , 51 ], and other two-dimensional materials [ 52 , 53 , 54 ] have been extensively investigated. Similarly, materials with internal nanostructures including mesoporous materials [ 55 , 56 , 57 ], zeolites [ 58 , 59 , 60 ], metal–organic frameworks [ 61 , 62 , 63 ], other coordination polymers [ 64 , 65 , 66 ], and covalent organic frameworks [ 67 , 68 , 69 ] have been actively explored.…”