Improving the performance of quantum dot light-emitting diodes through nanoscale engineering

Despite tremendous progress since the first demonstration of QDbased light-emitting diodes (QD-LEDs) there is substantial room for improvement in performance, particularly at high current densities. Here we analyze the role of Auger recombination in the performance of QD-LEDs by conducting a systematic characterization of device performance in conjunction with timeresolved spectroscopic studies of photoexcited carriers directly within the device structure. We use a series of structurally engineered core/shell QDs that exhibit very similar single-exciton properties, but distinctly different rates of non-radiative Auger recombination to show that both QD-LED efficiency and the onset for efficiency roll-off are strongly influenced by Auger recombination. Finally, we demonstrate that device efficiency can be improved by either reducing Auger recombination rates, or by improving charge-injection balance, both of which can be accomplished through engineering of the QD structure.