Highly luminescent and stable green-emitting In(Zn,Ga)P/ZnSeS/ZnS small-core/thick-multishell quantum dots

Abstract

Fluorescent InP-based quantum dots (QDs) have attracted much attention as materials for display applications. Over the past few years, persistent effort has focused on improving photoluminescence (PL) quantum yields and narrowing PL bandwidths through synthesis; as a consequence, the PL properties of InP-based QDs are now comparable to of those of CdSe QDs. Unfortunately, the lack of PL stability in degradable environments has hindered investigations into the applications of these materials. Herein, we report the synthesis of green-emitting In(Zn,Ga)P/ZnSeS/ZnS small-core/thick-multishell QDs that exhibit 78% of the maximum PL quantum yield. Zn and Ga impurities in the InP-QD cores reduce the lattice constant of the InP QDs, which facilitates the growth of thick ZnSeS/ZnS shells. Due to protection of the QD exciton, which is spread away from the surface of the In(Zn,Ga)P/ZnSeS (core/shell) structure by the perfect passivating properties of the thick ZnS shell, the green-emitting In(Zn,Ga)P/ZnSeS/ZnS (core/multishell) QDs are significantly more photostable than In(Zn,Ga)P/ZnSeS QDs. A close-packed QD film displayed bright green (532 nm) emission with suppressed concentration quenching, which is useful for environmentally friendly QD-based displays.