Optical Gain from Biexcitons in CsPbBr3 Nanocrystals Revealed by Two-dimensional Electronic Spectroscopy
- 27 February 2019
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry Letters
- Vol. 10 (6), 1251-1258
- https://doi.org/10.1021/acs.jpclett.9b00524
Abstract
Perovskite semiconductor nanocrystals (NCs) exhibit highly efficient optical gain which is promising for laser applications. However, the intrinsic mechanism of optical gain in perovskite NCs, particularly whether more than one exciton per NCs is required, remains to be poorly understood. Here, we use two-dimensional electronic spectroscopy to resonantly probe the interplay between near-band-edge transitions during the buildup of optical gain in CsPbBr3 NCs. We find compelling evidences to conclude that optical gain in CsPbBr3 NCs is generated through stimulated emission from strongly-interacting biexcitons. The threshold is largely determined by the competition between stimulated emission from biexcitons and excited-state absorption from single exciton to biexciton states. The findings in this work may guide future explorations of NC materials with low-threshold optical gain.Keywords
Funding Information
- National Natural Science Foundation of China (21873047, 91850105, 11574140, 91833305, 11621091,)
- National Key R&D Program of China (2018YFA0209100 and 2017YFA0303703)
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