Record-Breaking Far-Red Silicon Quantum Dots LEDs Enabled by Solvent Engineering: Toward Superseding Perovskite...

Most quantum dots (QDs) contain either toxic elements, which are health and environmental hazards, or costly precious metals. In contrast, as nanocrystals consisting mainly of an earth-abundant, light element, silicon QDs (SiQDs) have attracted attention as cost-effective biomedical, display, and solid-state lighting materials. However, unlike heavy-metal or perovskite QDs, SiQDs have not yet been used to create high-performance optoelectronics or long-lifetime light-emitting diodes (LEDs). Herein, the fabrication via solvent engineering of SiQD LEDs with record-breaking external quantum efficiency (16.5%) and lifetimes up to 733 times longer than the previous record is reported. Furthermore, the far-red (750 nm) luminance is comparable to that of state-of-the-art perovskite QD LEDs. Dispersing the SiQDs in octane yields particularly efficient LEDs owing to negligible SiQD aggregation, and Joule heating minimization realizes long-term stability (lifetime >200 h). Thus, solvent engineering is harnessed to break four QD LED performance records-for efficiency, luminance, voltage, and operational lifetime-using a more sustainable QD material, and the mechanisms underlying these performance improvements are unveiled. Thus, a new solvent-engineering approach for developing efficient, stable, and sustainable far-red SiQD LEDs, which are valuable light sources for applications including plant growth acceleration and photodynamic therapy, is highlighted.