Increased shell thickness in indium phosphide multishell quantum dots leading to efficiency and stability enhancement in light-emitting diodes

We report efficient indium phosphide (InP) quantum dot-based light-emitting diodes (QD-LEDs). The current efficiency and the device stability of QD-LEDs were enhanced by increasing the thickness of ZnS outer shell of InP/ZnSe/ZnS multishell QDs. Reversible luminance degradation was observed in operation of QD-LEDs, which was hypothesized to result from QD charging. QDs having thicker ZnS shell with strong confinement suppressed the luminescence quenching as well as QD charging. Our findings about the reversible QD charging and the developed performance by the thick ZnS outer shell would help to rationalize the luminance quenching issue in QD-LED operation.