Solution processed multilayer cadmium-free blue/violet emitting quantum dots light emitting diodes

We demonstrate blue/violet emitting devices based on cadmium-free zinc selenide/zinc sulfide core/shell quantum dots. Using poly(N-vinylcarbazole) with a low lying highest occupied molecular orbital energy for the hole transporting layer, enhanced hole injection was observed, resulting in efficient blue/violet emitting devices. The device charge balance was further enhanced by tuning the thicknesses of the hole transporting layer and quantum dot emitting layer.