Rigid CuInS₂/ZnS Core/Shell Quantum Dots\nfor High Performance Infrared Light-Emitting Diodes

Abstract

CuInS₂ (CIS) quantum dots (QDs) represent an important\nclass of colloidal materials with broad application potential, owing\nto their low toxicity and unique optical properties. Although coating\nwith a ZnS shell has been identified as a crucial method to enhance\noptical performance, the occurrence of cation exchange has historically\nresulted in the unintended formation of Cu–In–Zn–S\nalloyed QDs, causing detrimental blueshifts in both absorption and\nphotoluminescence (PL) spectral profiles. In this study, we present\na facile one-pot synthetic strategy aimed at impeding the cation exchange\nprocess and promoting ZnS shell growth on CIS core QDs. The suppression\nof both electron–phonon interaction and Auger recombination\nby the rigid ZnS shell results in CIS/ZnS core/shell QDs that exhibit\na wide near-infrared (NIR) emission coverage and a remarkable PL quantum\nyield of 92.1%. This effect boosts the fabrication of high-performance,\nQD-based NIR light-emitting diodes with the best stability of such\nmaterials so far.