Emission Enhancement of Cu-Doped InP Quantum Dots through Double Shelling Scheme.

The doping of transition metal ions, such as Cu+ and Mn2+ into a quantum dot (QD) host is one of the useful strategies in tuning its photoluminescence (PL). This study reports on a two-step synthesis of Cu-doped InP QDs double-shelled with ZnSe inner shell/ZnS outer shell. As a consequence of the double shelling-associated effective surface passivation along with optimal doping concentrations, Cu-doped InP/ZnSe/ZnS (InP:Cu/ZnSe/ZnS) QDs yield single Cu dopant-related emissions with high PL quantum yields of 57-58%. This study further attempted to tune PL of Cu-doped QDs through the variation of InP core size, which was implemented by adopting different types of Zn halide used in core synthesis. As the first application of doped InP QDs as electroluminescent (EL) emitters, two representative InP:Cu/ZnSe/ZnS QDs with different Cu concentrations were then employed as active emitting layers of all-solution-processed, multilayered QD-light-emitting diodes (QLEDs) with the state-of-the-art hybrid combination of organic hole transport layer plus inorganic electron transport layers. The EL performances, such as luminance and efficiencies of the resulting QLEDs with different Cu doping concentrations, were compared and discussed.

Electroluminescence from two I-III-VI quantum dots of A-Ga-S (A=Cu, Ag).

Together with III-V InP, chalcopyrite I-III-VI metal chalcogenides particularly with the compositions of A-B-S (A=Cu+, Ag+, B=In3+, Ga3+) are regarded as an emerging non-Cd class for synthesis of visible-emitting colloidal quantum dots (QDs) and the following fabrication of QD-light-emitting diodes (QLEDs). To date, the composition of I-III-VI QDs which were exploited for QLED fabrication remains highly limited, with most devices demonstrated from Cu-In-S-based ones. Herein, we explore the synthesis of two Ga-based I-III-VI QDs of Ag-Ga-S (AGS) and Cu-Ga-S (CGS) QDs and their application to QLED fabrication. Using cyan AGS/ZnS and azure CGS/ZnS core/shell QDs, all-solution-processed, multilayered QLEDs with a hybrid combination of organic hole transport layer and inorganic electron transport layer are fabricated and compared. We observe that CGS QLED by far outperforms in luminance and efficiency its AGS counterpart, which is ascribable to the differences in both electronic band structure and core/shell structure between two comparative QDs.