Near-Infrared Quantum Dots for Electroluminescence: Balancing Performance and Sustainability

Near-infrared quantum dots (NIR QDs) show promise in the fields of biomedicine, public health, and optoelectronics. Significant progress has been made in the development of efficient NIR light-emitting diodes (LEDs) through understanding the correlation between QD size and photophysical properties, along with research into QD passivation and device structure optimization. However, challenges remain in achieving long operational lifetime and low environmental hazard, which must be addressed to meet restriction of hazardous substances (RoHS) standards. In this review, the research progress on the synthesis and passivation of NIR QDs, as well as the efficiency and stability of NIR-quantum dot light-emitting diodes (QLEDs) are summarized. This is started with the synthesis and passivation strategies for common toxic and RoHS-compliant nonhazardous NIR QDs, highlighting passivation approaches that enhance photoluminescence quantum yield. Then, the fabrication and performance aspects of NIR QLEDs are investigated and the efficiency and stability of devices using toxic and nontoxic NIR QDs are summarized. Finally, the latest advances are summarized by highlighting the necessary balance between conventional high-performance QDs and more environmentally friendly RoHS-compliant QDs, and the move of focus is discussed to the long-term challenge of combining device performance with environmental sustainability and what needs to do toward this goal.