Colloidal quantum dots have attracted a lot of attention as prototype light emitting devices, not only due to their high quantum yield but also the ease of controlling their emission properties. Lasing from colloidal quantum dot films has already been reported, limited to nanoseconds. Ted Sargent and collaborators now report lasing, sustained for microseconds. Contrary to previous reports that linked poor lasing behaviour to Auger recombination, the team focused on the role of heating of the samples. The researchers studied very thin films of CdSe–CdS–ZnS core–shell–shell dots, integrated with highly conductive substrates and succeeded in observing lasing on a microsecond timescale. Their findings underline the role of poor thermal management on the quest for lasing, coming from heating from the pump source. The authors believe that a further decrease in the lasing threshold, combined with a highly thermally conductive substrate that also supports low-loss optical propagation, will allow for the observation of continuous-wave lasing.
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Maragkou, M. Long-lived lasing. Nature Mater 14, 1186 (2015). https://doi.org/10.1038/nmat4504