ZnSeTe Quantum Dots as an Alternative to InP and Their High-Efficiency Electroluminescence

Abstract

Last decade witnessed great advancement in the photoluminescent (PL) quality of visible III–V InP quantum dots (QDs) toward bright, sharp emissivity. Now, InP QDs hold an unrivaled position in the field of next-generation display devices. In an effort to offer non-Cd green QDs as potential alternatives to InP counterparts, in this work, the first viable synthesis of II–VI ternary ZnSeTe QDs is explored. After successful growth of ZnSeTe alloy cores enabled by a balanced precursor reactivity of anions (i.e., Se and Te), sequential triple shells of ZnSe/ZnSeS/ZnS with stepwise type-I energetic potentials are formed. The resulting heterostructured ZnSeTe/ZnSe/ZnSeS/ZnS QDs produce tunable PL wavelengths of 495–532 nm along with high PL quantum yields (QY) of 68–83%, depending on a Te/Se feed molar ratio used for core synthesis. To further evaluate performance of the present ZnSeTe QDs as electroluminescent (EL) emitters, the first fabrication of a solution-processed, multilayered green QD-light-emitting diode (QLED) by adopting Te/Se = 0.28-based triple-shelled QDs with a PL peak of 520 nm and QY of 80% is demonstrated. This device produces promising EL outcomes up to 18 420 cd/m2 in luminance and 7.6% in external quantum efficiency, outperforming most of green InP QLEDs reported to date.