Temperature-dependent photoluminescence of CuInS2 quantum dots

Temperature-dependent photoluminescence (PL) spectroscopy of CuInS2 core and CuInS2/ZnS core–shell quantum dots (QDs) was studied for understanding the influence of a ZnS shell on the PL mechanism. The PL quantum yield and lifetime of CuInS2 core QDs were significantly enhanced after the QD surface was coated with the ZnS shell. The temperature dependences of the PL energy, linewidth, and intensity for the core and core–shell QDs were studied in the temperature range from 92 to 287 K. The temperature-dependent shifts of 98 meV and 35 meV for the PL energies of the QDs were much larger than those of the excitons in their bulk semiconductors. It was surprisingly found that the core and core–shell QDs exhibited a similar temperature dependence of the PL intensity. The PL in the CuInS2/ZnS core–shell QDs was suggested to originate from recombination of many kinds of defect-related emission centers in the interior of the cores.