Water-Soluble Alumina-Coated Indium Phosphide Core-Shell Quantum Dots with Efficient Deep-Red Emission Beyond 700 nm

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Cadmium-based quantum dots (QDs) face environmental concerns.
• Indium Phosphide (InP) QDs are promising alternatives but struggle with deep-red emission.
• Achieving narrow linewidths in deep-red emission remains a challenge for optoelectronic applications.

Purpose of the Study:

• To develop novel InP/ZnSe/ZnS core-shell-shell quantum dots (QDs) for emission in the first biological transparency window.
• To enhance the biocompatibility and stability of QDs for advanced applications.
• To create environmentally friendly alternatives to Cadmium-based QDs.

Main Methods:

• Synthesis of InP/ZnSe/ZnS core-shell-shell QDs.
• Surface passivation with amorphous alumina (Al2O3) to form InP/ZnSe/ZnS/Al2O3 heterostructures.
• Aqueous phase transfer using mercaptopropionic acid (MPA) ligand exchange.

Main Results:

• Achieved deep-red emission up to 725 nm with narrow peak full width at half maximum (FWHM) down to 107 meV (45 nm).
• Alumina capping enhanced environmental and photostability, improving photoluminescence quantum yield (PLQY).
• Maintained quantum yield after aqueous phase transfer.

Conclusions:

• The novel InP/ZnSe/ZnS/Al2O3 QDs are suitable for the first biological transparency window.
• These QDs offer a stable, bright, and environmentally friendly alternative for optoelectronics and bio-applications.
• The developed QDs show potential for next-generation technologies.