Tamarat Philippe, Hou Lei, Trebbia Jean-Baptiste, Swarnkar Abhishek, Biadala Louis, Louyer Yann, Bodnarchuk Maryna I, Kovalenko Maksym V, Even Jacky, Lounis Brahim
Université de Bordeaux, LP2N, F-33405, Talence, France.
Institut d'Optique and CNRS, LP2N, F-33405, Talence, France.
Nat Commun. 2020 Nov 26;11(1):6001. doi: 10.1038/s41467-020-19740-7.
Cesium lead halide perovskites exhibit outstanding optical and electronic properties for a wide range of applications in optoelectronics and for light-emitting devices. Yet, the physics of the band-edge exciton, whose recombination is at the origin of the photoluminescence, is not elucidated. Here, we unveil the exciton fine structure of individual cesium lead iodide perovskite nanocrystals and demonstrate that it is governed by the electron-hole exchange interaction and nanocrystal shape anisotropy. The lowest-energy exciton state is a long-lived dark singlet state, which promotes the creation of biexcitons at low temperatures and thus correlated photon pairs. These bright quantum emitters in the near-infrared have a photon statistics that can readily be tuned from bunching to antibunching, using magnetic or thermal coupling between dark and bright exciton sublevels.
卤化铯铅钙钛矿在光电子学的广泛应用以及发光器件中展现出卓越的光学和电子特性。然而，作为光致发光起源的带边激子的物理性质尚未阐明。在此，我们揭示了单个碘化铯铅钙钛矿纳米晶体的激子精细结构，并证明其受电子 - 空穴交换相互作用和纳米晶体形状各向异性的支配。能量最低的激子态是一个长寿命的暗单重态，它在低温下促进双激子的产生，从而产生关联光子对。利用暗激子和亮激子子能级之间的磁耦合或热耦合，这些近红外的明亮量子发射器的光子统计特性能够很容易地从聚束调谐到反聚束。
