Blach Daria D, Lumsargis Victoria A, Clark Daniel E, Chuang Chern, Wang Kang, Dou Letian, Schaller Richard D, Cao Jianshu, Li Christina W, Huang Libai
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 1A4, Canada.
Nano Lett. 2022 Oct 12;22(19):7811-7818. doi: 10.1021/acs.nanolett.2c02427. Epub 2022 Sep 21.
Achieving superradiance in solids is challenging due to fast dephasing processes from inherent disorder and thermal fluctuations. Perovskite quantum dots (QDs) are an exciting class of exciton emitters with large oscillator strength and high quantum efficiency, making them promising for solid-state superradiance. However, a thorough understanding of the competition between coherence and dephasing from phonon scattering and energetic disorder is currently unavailable. Here, we present an investigation of exciton coherence in perovskite QD solids using temperature-dependent photoluminescence line width and lifetime measurements. Our results demonstrate that excitons are coherently delocalized over 3 QDs at 11 K in superlattices leading to superradiant emission. Scattering from optical phonons leads to the loss of coherence and exciton localization to a single QD at temperatures above 100 K. At low temperatures, static disorder and defects limit exciton coherence. These results highlight the promise and challenge in achieving coherence in perovskite QD solids.
由于固有无序和热涨落导致的快速退相过程，在固体中实现超辐射具有挑战性。钙钛矿量子点（QDs）是一类令人兴奋的激子发射体，具有大的振子强度和高量子效率，使其有望实现固态超辐射。然而，目前尚无法全面了解声子散射和能量无序导致的相干与退相之间的竞争关系。在此，我们通过依赖温度的光致发光线宽和寿命测量，对钙钛矿量子点固体中的激子相干性进行了研究。我们的结果表明，在超晶格中，激子在11 K时在3个量子点上相干离域，导致超辐射发射。在高于100 K的温度下，光学声子的散射导致相干性丧失，激子定域到单个量子点上。在低温下，静态无序和缺陷限制了激子相干性。这些结果凸显了在钙钛矿量子点固体中实现相干性的前景和挑战。
