An All‐Colloidal and Eco‐Friendly Quantum‐Dot Laser

Abstract Colloidal zinc‐chalcogenide quantum dots (QDs) are emerging as the promising heavy‐metal‐free light–emitters, however, the development of light amplification and lasing therein remains challenging. Here, corroborated by comprehensive in situ and transient spectroscopy, it is unraveled that the ultrafast photooxidization‐induced trapping process (≈2 ps) and the sub‐bandgap photoinduced absorption under intense excitation are the main hindrances to light amplification in ZnSeTe QDs. Upon tackling the hurdle by heterostructure engineering, this study demonstrates that the ZnSeTe QDs exhibit intrinsically superior gain performance, including the high gain cross‐section (5.6 × 10 −16 cm 2 ), long gain lifetime (615 ps), low pump threshold (≈25.9 µJ cm −2 ) and high fatigue resistance. On this basis, a microfluidic channel is designed to mass‐produce the micellar cavities whose surfaces are treated to combine with the ZnSeTe QDs. The active QD‐micelle hybrids show state‐of‐the‐art lasing performance and allow the fiber‐based micro‐manipulation toward the single‐mode lasers. These findings not only provide essential knowledge on the gain physics in ZnSeTe QDs, but also open a new avenue to develop high‐performance eco‐friendly lasers.