Intrinsic Defect Self-Compensation Enables Spectrum Narrowing of Uniform Alloyed Ag–In–Ga–S Quantum Dots

Eco-friendly Ag–In–Ga–S (AIGS) quantum dots (QDs) are promising alternatives to toxic Pb/Cd-containing QDs due to their tunable emission, high photoluminescence quantum yield (PLQY), and solution processability. However, their intrinsic defect-driven broad emission limits applications in high-resolution displays. Herein, we report a synthesis of uniform alloyed AIGS QDs with narrow emission via defect self-compensation, circumventing intricate shell growth. Benefiting from the defect compensation of interstitial Ag (Ag i ) to Ag vacancy (V Ag ) under thermal activation, structural defects are significantly suppressed, achieving tunable emission with remarkably narrow full width at half-maximum (fwhm = 30–38 nm) and high PLQYs. The resulting quantum dot light-emitting diodes (QLEDs) exhibit electroluminescence with fwhm < 40 nm, validating high-purity display compatibility. The simplified approach and mechanistic clarity advance the production of high-color-purity AIGS QLEDs, offering a paradigm for narrow emission in eco-friendly I–III–VI QDs.