Stable, Efficient, and Scalable Multicolor Lasing from Colloidal Quantum Dots in Liquids.

Liquid-state optical gain media are desired for high-power lasing applications due to their easier heat management than solid-state media, as well as for the emerging field of optofluidics. Colloidal quantum dots (QDs) are solution-processed materials that carry many attractive properties suitable for liquid lasing. To date, however, their lasing action is often achieved in close-packed films, as a high volume fraction of QDs is required for stimulated emission to outpace the ultrafast Auger decay of gain-active multiexciton states. Here we report liquid lasing from color-tunable (red, orange, and green) alloyed core/shell QDs with impeded Auger recombination. Lasing action is achieved by loading the QD-solutions into cavities under quasi-continuous-wave excitation. The light amplification behaviors of QD-solutions under ambient conditions are much more stable compared to those of both solid-state QD-films and dye solutions. Compatibility with aqueous solvents and ease of scalability are also demonstrated. An optimized optical power efficiency of 17.2% has been achieved. These results indicate that liquid lasing from colloidal QDs holds strong promise for real-world implementation.