Low temperature synthesis of highly bright green emission CuInS2/ZnS quantum dots and its application in light-emitting diodes

Abstract

In this study, an efficient green light-emitting CuInS2/ZnS core/shell quantum dots were synthesized using a low temperature (130 °C) hot injection methods combined with multi-layers ZnS coating strategy. S-OAm (S powder dissolved in oleylamine) was used as sulfur source instead of conventional dodecanethiol, which supplied high concentration of H2S at low temperature and led to explosive nucleation of CuInS2 and hence high concentration small size of CIS cores. Meanwhile, this method could supply enough sulfur sources for the ZnS coating process, resulting in high quality ZnCuInS2 alloyed interface and ZnS surface coating layers, which led to excellent lattice match between the CuInS2 core and ZnS shells, and better surface passivation. As the consequence, a maximum photoluminescence quantum yields of ∼85% at peak wavelength of ∼530 nm has been achieved. Based on this, the light emitting diodes with a maximum luminance of 4450 cd m−2, luminous efficiency of 3.52 cd A−1 and an external quantum efficiency of 1.44% has been obtained, which is the best result so far for the green emission light emitting diodes based on the CuInS2 quantum dots.