Redox-Tuned Three-Color Emission in Double (Mn and Cu) Doped Zinc Sulfide Quantum Dots
Raihana Begum1, Arun Chattopadhyay1
1†Department of Chemistry and ‡Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781 039, India.
Abstract:
The photoluminescence characteristics of colloidal Mn(2+) and Cu(2+) (double) doped zinc sulfide (ZnS) quantum dots (Qdots) could be drastically influenced by reactions with redox reagents. Importantly, experiments revealed Cu(+) in ZnS nanocrystals rather than Cu(2+), in conjunction with Mn(2+), as the emitting dopant. Thus, as-synthesized aqueous Qdots emitted orange (with peaks at 460 and 592 nm) due to the host and Mn(2+) dopant emissions. However, upon treatment with a reducing agent, the color changed to yellow with dual peaks positioned at 520 and 590 nm due to Cu(+) and Mn(2+) dopant emissions. The characteristics could be changed reversibly with appropriate redox reagents. Further, treatment with excess of an oxidizing agent led to blue emission with a single peak at 450 nm.
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