Amara Mohamed-Raouf, Said Zakaria, Huo Caixia, Pierret Aurélie, Voisin Christophe, Gao Weibo, Xiong Qihua, Diederichs Carole
Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, F-75005 Paris, France.
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
Nano Lett. 2023 Apr 26;23(8):3607-3613. doi: 10.1021/acs.nanolett.3c00793. Epub 2023 Apr 4.
Lead halide perovskite nanocrystals are promising materials for classical and quantum light emission. To understand these outstanding properties, a thorough analysis of the band-edge exciton emission is needed, which is not reachable in ensemble and room-temperature studies because of broadening effects. Here, we report on a cryogenic-temperature study of the photoluminescence of single CsPbBr nanocrystals in the intermediate quantum confinement regime. We reveal the size-dependence of the spectral features observed: the bright triplet exciton energy splittings, the trion and biexciton binding energies, and the optical phonon replica spectrum. In addition, we show that bright triplet energy splittings are consistent with a pure exchange model and that the variety of polarization properties and spectra recorded can be rationalized simply by considering the orientation of the emitting dipoles and the populations of the emitting states.
卤化铅钙钛矿纳米晶体是用于经典和量子发光的有前途的材料。为了理解这些优异的性质，需要对带边激子发射进行深入分析，而在室温下对整体样品的研究中，由于展宽效应，这是无法实现的。在此，我们报道了在中间量子限域 regime 下对单个 CsPbBr 纳米晶体光致发光的低温研究。我们揭示了所观察到的光谱特征的尺寸依赖性：明亮的三重态激子能量分裂、三重子和双激子结合能以及光学声子复制光谱。此外，我们表明明亮的三重态能量分裂与纯交换模型一致，并且通过考虑发射偶极子的取向和发射态的布居数，可以简单地解释所记录的各种偏振性质和光谱。
