| 초록 |
Type-I core/shell heterostructures have been widely adopted for colloidal quantum dots (QDs) for high quantum yield (QY) emitters. While a neutral exciton QY has been a major metric for efficient QD-based light-emitting diodes, continuing study suggests the importance of multicarrier exciton species such as negative trion or biexcitons. However, satisfying both metrics is still challenging; complicated fabrication processes for high multiexciton QYs necessarily leave defect states in the QDs, so degrade neutral exciton QYs. Here, we suggest a novel approach utilizing the lattice strain to achieve high QYs for any exciton species. We exclude internal defects introduced during the shell growth by utilizing compressive strain by shell phase. Spectroscopic probes disclose that compressive ZnSeS shell lifts the core state with respect to the defect states, so thus, prevents trap-assisted nonradiative pathways. Our strain-engineered QDs exhibit near unity PL QYs and ＞50% biexciton QY. |
