Controlling the shell growth mechanism and interfacial oxidation of InAs/ZnSe quantum dots for shortwave infrared...

Short-wave infrared (SWIR) emitters underpin applications in communication, imaging and sensing, yet efficient, scalable devices remain limited. Colloidal InAs quantum dots (InAs CQDs) offer a compelling, cost-effective alternative to conventional epitaxial SWIR light-emitting diodes (LEDs). However, developing heavy-metal-free InAs CQDs for emission beyond 1400 nm is hindered by lattice mismatch during core/shell growth, which degrades photoluminescence quantum yield (PLQY). Furthermore, integrating CQDs into LEDs often introduces severe interfacial quenching and intrinsic charge imbalances. Here we report a highly efficient heavy-metal-free SWIR LED operating at 1525 nm, enabled by tailored injection strategies and oxidation-induced interfacial engineering. Optimized high-temperature ZnCl₂ treatment and continuous precursor injection improve shell nucleation and growth, while controlled interfacial oxidation is associated with reduced shell-thickness-dependent strain signatures and improved PLQY retention during shell thickening. Together, these strategies yield measured PLQYs exceeding 55% for emission beyond 1400 nm. Moreover, we demonstrate that incorporating a semiconducting InAs CQD interlayer effectively suppresses interfacial quenching and regulates electron over-injection. Combined with a doped hole-transport layer to reduce series resistance, our optimized devices achieve a maximum external quantum efficiency of 3.5% and a record radiance of ~17 W sr^-1 m^-2, alongside a T50 operational lifetime of 16 h. Our findings suggest that integrating mechanism-driven shell growth with rational device engineering offers a strategy to overcome current bottlenecks in colloidal emitters, facilitating the transition toward short-wave infrared applications.