Sub-single exciton optical gain threshold in colloidal semiconductor quantum wells with gradient alloy shelling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32620749.
- Also identified by DOI 10.1038/s41467-020-17032-8 and PMC identifier 7335098.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Colloidal semiconductor quantum wells have emerged as a promising material platform for use in solution-processable lasers. However, applications relying on their optical gain suffer from nonradiative Auger decay due to multi-excitonic nature of light amplification in II-VI semiconductor nanocrystals. Here, we show sub-single exciton level of optical gain threshold in specially engineered CdSe/CdS@CdZnS core/crown@gradient-alloyed shell quantum wells. This sub-single exciton ensemble-averaged gain threshold of (N<sub>g</sub>)≈ 0.84 (per particle) resulting from impeded Auger recombination, along with a large absorption cross-section of quantum wells, enables us to observe the amplified spontaneous emission starting at an ultralow pump fluence of ~ 800 nJ cm<sup>-2</sup>, at least three-folds better than previously reported values among all colloidal nanocrystals. Finally, using these gradient shelled quantum wells, we demonstrate a vertical cavity surface-emitting laser operating at a low lasing threshold of 7.5 μJ cm<sup>-2</sup>. These results represent a significant step towards the realization of solution-processable electrically-driven colloidal lasers.