In/Ga Stoichiometry Locking toward Narrow-Bandwidth Red AgInGaS QLEDs via Aluminum Anchoring

Ag–In–Ga–S (AIGS) quantum dots (QDs) are promising candidates for optoelectronics due to their tunable emission and eco-friendly components. However, obtaining narrow-bandwidth red emission at 630–650 nm remains challenging, mainly due to the difficulty in achieving a high In/Ga stoichiometric ratio caused by interface cation diffusion during synthesis. Herein, we develop an Al3+-anchoring strategy to lock In3+ and promotes In/Ga stoichiometric ratio. First-principles calculations confirm that In vacancies are preferentially generated, lowering the effective In/Ga ratio. Al incorporation effectively suppresses In vacancies and blocks cation interdiffusion, as evidenced by XPS depth-profiling and EDS. Consequently, the photoluminescence red-shifts from 597 to 635 nm without broadening the fwhm, with a 20% increase in PLQY. Al-anchored QLEDs achieve a luminance of ∼500 cd m–2, a narrow fwhm of 36 nm, and a peak EQE of 2.4%, offering an effective route to regulate cation stoichiometry and suppress defect states for cadmium-free pure-red emitters.