Red Ag-Based I–III–VI Quantum Dots as Competitive Alternatives to InP Emitters

Heavy metal-free I–III–VI quantum dots (QDs), particularly those incorporating Ag and Cu, are promising ecofriendly alternatives to Cd- and Pb-based QDs. Yet, achieving both high photoluminescence quantum yield (PL QY) and narrow emission in red-emissive I–III–VI QDs remains a significant challenge. Herein, we systematically synthesize red-emitting Ag-based ternary, quaternary, and quinary I–III–VI QDs via core size tuning, compositional engineering, and GaSx shelling. Optimizing the Se/S ratio and introducing Ga3+ into the core yield Ag–In–Ga–S–Se (AIGSSe) QDs with an outstanding PL QY of 82% and a narrow bandwidth of 46 nm. These QDs surpass conventional Ag-based QDs in optical quality and outperform red InP QDs in light absorption and blue-to-QD color conversion efficiency. The AIGSSe QDs thus present a compelling alternative for next-generation QD display applications, offering a unique combination of high emissivity, narrow bandwidth, and strong absorption.