Light-Emitting Devices Based on Type-II InP/ZnO Quantum Dots

One of the major challenges for present-day quantum dot light-emitting diode (QLED) technology is the transition from toxic heavy metal to "green" material-based devices. This report proposes an alternative cadmium-free material of type-II InP/ZnO core/shell quantum dots (QDs) for QLEDs. In this study, InP/ZnO core/shell QDs are nanoengineered by adjusting the shell coverage for optimum in-film quantum efficiency, and device parameters are investigated to reach a maximum QLED performance. The fully solution processed QLEDs made of biocompatible and environmentally benign QDs presented in this study exhibit low turn on voltage of 2.8 V, external quantum efficiency of 0.53%, and current efficiency of 1 cd/A, with a saturated color emission in the yellow-orange spectral region. This study paves the way towards nontoxic and efficient LEDs using type-II QDs.