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Alloying Ag2S Quantum Dots with Gold: Controlling NIR-I Emission with Material Modification.
Kanik Chelani1, Thomas W Price1, Victor Gonçalves2
1Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, 4th Floor Lambeth Wing, London, SE1 7EH, UK.
Small (Weinheim an Der Bergstrasse, Germany)
|September 1, 2025
Summary
This study details the creation of tunable near-infrared-I (NIR-I) emitting gold-alloyed silver sulfide quantum dots (QDs). Adjusting the gold to silver ratio precisely controls their emission color and enhances their photoluminescence quantum yields and lifetimes.
Area of Science:
- Materials Science
- Nanotechnology
- Optoelectronics
Background:
- Silver sulfide quantum dots (Ag2S QDs) are promising for near-infrared (NIR) applications.
- Tuning the optoelectronic properties of Ag2S QDs remains a challenge.
Purpose of the Study:
- To prepare tunable NIR-I emitting Au-alloyed Ag2S QDs.
- To elucidate the relationship between structural evolution and optoelectronic properties.
- To develop QDs compatible with biological imaging.
Main Methods:
- Controlled synthesis of Au-alloyed Ag2S QDs via Au:Ag stoichiometry.
- Structural characterization using advanced techniques.
- Ligand exchange for aqueous media transfer.
- Evaluation of photoluminescence properties (PLQY, lifetime).
Main Results:
- Tunable NIR-I emission (715-1180 nm) achieved by varying Au:Ag ratio.
- Enhanced photoluminescence quantum yields (up to 26.7%) and prolonged lifetimes (up to 4.57 µs).
- Formation of new crystalline phases (Ag3AuS2, AgAuS, AgAu3) and cation exchange observed.
- Aqueous stable AgAuS QDs with emission at 845 nm were successfully prepared.
Conclusions:
- Au-alloying provides a robust method for tuning the optoelectronic properties of Ag2S QDs.
- The structural evolution directly correlates with the observed optical property changes.
- The developed QDs show potential for NIR-I bioimaging applications.
