Colloidal quantum well light-emitting diodes (CQW-LEDs) hold tremendous potential for next-generation display and lighting applications, owing to their high color purity, excellent efficiency, and low fabrication cost. However, efficiency roll-off at high current density makes it challenging to achieve high brightness and long lifetime. Here, we designed CdSe/ZnSe/ZnS core/shell/shell CQWs with near-unity photoluminescence quantum yield. The graded heterostructure promotes carrier injection, and the bottom-emission device based on CdSe/ZnSe/ZnS CQWs exhibits remarkably suppressed efficiency roll-off with a record-high J90 (current density for EQE to decrease to 90%) of 485 mA/cm2 and a long operational lifetime (T95 @ 100 cd/m2) over 47000 h. In addition, the top-emission device also shows low efficiency roll-off and high current efficiency of 36.5 cd/A. This study provides a compositionally graded approach to suppress efficiency roll-off in CQW-LEDs, demonstrating the strong potential of the newly developed CQWs for next-generation ultrabright and highly efficient optoelectronic devices.
Qiu et al. (2026) studied this question.