Suppression of Auger Recombination by Gradient Alloying in InAs/CdSe/CdS QDs
Laxmi Kishore Sagar, Golam Bappi, Andrew Johnston, Bin Chen, Petar Todorović́, Larissa Levina, Makhsud I. Saidaminov, F. Pelayo Garcı́a de Arquer, Dae‐Hyun Nam, Min‐Jae Choi, Sjoerd Hoogland, Oleksandr Voznyy, Edward H. Sargent
Abstract
Colloidal quantum dots are promising for low-cost optoelectronic devices such as solar cells, light-emitting diodes (LEDs), lasers, and photodetectors. InAs-based quantum dots (QDs) are well suited for near-infrared (NIR) applications; however, to date, the highest-QY InAs QDs have exhibited short biexciton Auger lifetimes of ∼<50 ps. Here, we report a band engineering strategy that doubles the Auger lifetime in InAs CQDs. By developing a continuously graded thick CdSexS1–x shell, we synthesize InAs/CdSexS1–x/CdS CQDs that enable a smooth progression from the core to the outer shell, slowing the Auger process. We report a biexciton Auger lifetime of ∼105 ps compared to 17 ps for control InAs/CdSe/CdS CQDs. This represents a 2× increase of the Auger lifetime relative to the best value reported for InAs CQDs in prior literature.