Quasi-Shell-Growth Strategy Achieves Stable and Efficient Green InP Quantum Dot Light-Emitting Diodes.

ABSTRACT

Indium phosphide (InP) based quantum dots (QDs) have been known as an ideal alternative to heavy metals including QDs light emitters, such as cadmium selenium (CdSe) QDs, and show great promise in the next-generation solid-state lighting and displays. However, the electroluminescence performance of green InP QDs is still inferior to their red counterparts, due to the higher density of surface defects and the wider particle size distribution. Here, a quasi-shell-growth strategy for the growth of highly luminescent green InP/ZnSe/ZnS QDs is reported, in which the zinc and selenium monomers are added at the initial nucleation of InP stage to adsorb on the surface of InP cores that create a quasi-ZnSe shell rather than a bulk ZnSe shell. The quasi-ZnSe shell reduces the surface defects of InP core by passivating In-terminated vacancies, and suppresses the Ostwald ripening of InP core at high temperatures, leading to a photoluminescence quantum yield of 91% with a narrow emission linewidth of 36 nm for the synthesized InP/ZnSe/ZnS QDs. Consequently, the light-emitting diodes based on the green QDs realize a maximum luminance of 15606 cd m-2 , a peak external quantum efficiency of 10.6%, and a long half lifetime of > 5000 h.