Université de Bordeaux, LP2N, Talence, F-33405, France.
Institut d'Optique and CNRS, LP2N, Talence, F-33405, France.
Nat Commun. 2023 Jan 16;14(1):229. doi: 10.1038/s41467-023-35842-4.
Lead halide perovskites open great prospects for optoelectronics and a wealth of potential applications in quantum optical and spin-based technologies. Precise knowledge of the fundamental optical and spin properties of charge-carrier complexes at the origin of their luminescence is crucial in view of the development of these applications. On nearly bulk Cesium-Lead-Bromide single perovskite nanocrystals, which are the test bench materials for next-generation devices as well as theoretical modeling, we perform low temperature magneto-optical spectroscopy to reveal their entire band-edge exciton fine structure and charge-complex binding energies. We demonstrate that the ground exciton state is dark and lays several millielectronvolts below the lowest bright exciton sublevels, which settles the debate on the bright-dark exciton level ordering in these materials. More importantly, combining these results with spectroscopic measurements on various perovskite nanocrystal compounds, we show evidence for universal scaling laws relating the exciton fine structure splitting, the trion and biexciton binding energies to the band-edge exciton energy in lead-halide perovskite nanostructures, regardless of their chemical composition. These scaling laws solely based on quantum confinement effects and dimensionless energies offer a general predictive picture for the interaction energies within charge-carrier complexes photo-generated in these emerging semiconductor nanostructures.
卤铅钙钛矿在光电领域展现出广阔的前景，在量子光学和基于自旋的技术中有大量潜在的应用。鉴于这些应用的发展，精确了解电荷载流子复合物发光的基本光学和自旋特性至关重要。我们在近乎块状的铯铅溴单钙钛矿纳米晶体上进行低温磁光光谱测量，以揭示其整个带边激子精细结构和电荷复合物结合能。我们证明基态激子是暗态的，位于最低亮激子亚能级以下几个毫电子伏特，这解决了关于这些材料中亮暗激子能级序的争论。更重要的是，将这些结果与各种钙钛矿纳米晶化合物的光谱测量相结合，我们证明了在卤铅钙钛矿纳米结构中，激子精细结构分裂、三电子和双电子复合物结合能与带边激子能量之间存在普遍的标度定律的证据，无论其化学成分如何。这些仅基于量子限制效应和无量纲能量的标度定律为在这些新兴半导体纳米结构中光生电荷载流子复合物内的相互作用能量提供了一个通用的预测图景。
