Optical Gain from Biexcitons in CsPbBr3 Nanocrystals Revealed by Two-dimensional Electronic Spectroscopy,The Journal of Physical Chemistry Letters

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Optical Gain from Biexcitons in CsPbBr3 Nanocrystals Revealed by Two-dimensional Electronic Spectroscopy
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2019-02-27 00:00:00 , DOI: 10.1021/acs.jpclett.9b00524
Wei Zhao _{1,

2} , Zhengyuan Qin ₂ , Chunfeng Zhang ₂ , Guodong Wang ₂ , Xinyu Huang ₂ , Bin Li ₂ , Xingcan Dai ₁ , Min Xiao _{2,

3}

Affiliation

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 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 evidence 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.

中文翻译：

二维电子光谱显示的CsPbBr ₃纳米晶体中双激子的光学增益

钙钛矿半导体纳米晶体（NCs）表现出高效的光学增益，这对于激光应用是有前途的。但是，钙钛矿型NC的光学增益的内在机制，尤其是每个NC是否需要一个以上的激子，仍然知之甚少。在这里，我们使用二维电子光谱来共振探测CsPbBr ₃ NC中光学增益建立过程中近带边缘跃迁之间的相互作用。我们发现有力的证据可以得出结论，CsPbBr _3的光学增益NCs是通过强烈相互作用的双激子的受激发射产生的。该阈值主要由双激子的激发发射与单激子到双激子态的激发态吸收之间的竞争决定。这项工作中的发现可能会指导未来具有低阈值光学增益的NC材料的探索。

更新日期：2019-02-27

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