Kazes Miri, Nakar Dekel, Cherniukh Ihor, Bodnarchuk Maryna I, Feld Leon G, Zhu Chenglian, Amgar Daniel, Rainò Gabriele, Kovalenko Maksym V, Oron Dan
Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel.
Laboratory for Thin Films and Photovoltaics, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
Nano Lett. 2024 Oct 23;24(42):13185-13191. doi: 10.1021/acs.nanolett.4c03096. Epub 2024 Oct 14.
Colloidal semiconductor nanocrystals have long been considered a promising source of time-correlated and entangled photons via the cascaded emission of multiexcitonic states. The spectroscopy of such cascaded emission, however, is hindered by efficient nonradiative Auger-Meitner decay, rendering multiexcitonic states nonemissive. Here we present room-temperature heralded spectroscopy of three-photon cascades from triexcitons in giant CsPbBr nanocrystals. We show that this system exhibits second- and third-order correlation function values, g(0) and g(0,0), close to unity, identifying very weak binding of both biexcitons and triexcitons. Combining fluorescence lifetime analysis, photon statistics, and spectroscopy, we can readily identify emission from higher multiexcitonic states. We use this to verify emission from a single emitter despite high emission quantum yields of multiply excited states and comparable emission lifetimes of singly and multiply excited states. Finally, we present potential pathways toward control of the photon number statistics of multiexcitonic emission cascades.
长期以来，胶体半导体纳米晶体一直被认为是通过多激子态的级联发射产生时间关联光子和纠缠光子的一个有前景的来源。然而，这种级联发射的光谱受到高效非辐射俄歇-迈特纳衰变的阻碍，使得多激子态不发光。在此，我们展示了在巨型CsPbBr纳米晶体中来自三激子的三光子级联的室温预示光谱。我们表明，该系统表现出接近1的二阶和三阶关联函数值g(0)和g(0,0)，这表明双激子和三激子的束缚都非常弱。结合荧光寿命分析、光子统计和光谱学，我们能够轻松识别来自更高多激子态的发射。尽管多激发态具有高发射量子产率且单激发态和多激发态具有相当的发射寿命，但我们仍利用此方法验证了单个发射体的发射。最后，我们展示了控制多激子发射级联的光子数统计的潜在途径。
