Colloidal Second Near‐Infrared‐Emitting Mn‐Doped Ag2S Quantum Dots

Abstract Incorporation of transition metal dopants within a semiconductor nanocrystal has a tremendous effect on the optical and magnetic properties of the semiconductor nanocrystals. Herein, we report on a novel synthesis of second near‐infrared‐emitting photoluminescent Mn 2+ ‐doped Ag 2 S quantum dots via co‐pyrolysis of silver and manganese single‐source precursors. The Mn 2+ doping level was flexibly tuned in Ag 2 S quantum dots, which was confirmed by elemental analysis and electron paramagnetic resonance spectroscopy. The Mn 2+ doping induced negligible change in the pristine monoclinic acanthite Ag 2 S crystal structure but significantly decreased the photoluminescent intensity. Mn 2+ ‐doped Ag 2 S QDs exhibit second near‐infrared emission and ferromagnetic ordering, which show the potential applicability for multimodal fluorescence/MRI probes.