Wang Shuli, Dyksik Mateusz, Lampe Carola, Gramlich Moritz, Maude Duncan K, Baranowski Michał, Urban Alexander S, Plochocka Paulina, Surrente Alessandro
Laboratoire National des Champs Magnétiques Intenses, EMFL, CNRS UPR 3228, Université Grenoble Alpes, Université Toulouse, Université Toulouse 3, INSA-T, 38042 Grenoble and 31400 Toulouse, France.
Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland.
Nano Lett. 2022 Sep 14;22(17):7011-7019. doi: 10.1021/acs.nanolett.2c01826. Epub 2022 Aug 29.
The optimized exploitation of perovskite nanocrystals and nanoplatelets as highly efficient light sources requires a detailed understanding of the energy spacing within the exciton manifold. Dark exciton states are particularly relevant because they represent a channel that reduces radiative efficiency. Here, we apply large in-plane magnetic fields to brighten optically inactive states of CsPbBr-based nanoplatelets for the first time. This approach allows us to access the dark states and directly determine the dark-bright splitting, which reaches 22 meV for the thinnest nanoplatelets. The splitting is significantly less for thicker nanoplatelets due to reduced exciton confinement. Additionally, the form of the magneto-PL spectrum suggests that dark and bright state populations are nonthermalized, which is indicative of a phonon bottleneck in the exciton relaxation process.
将钙钛矿纳米晶体和纳米片作为高效光源进行优化利用，需要详细了解激子多重态内的能量间距。暗激子态尤为重要，因为它们代表了降低辐射效率的一个通道。在此，我们首次施加面内强磁场来点亮基于CsPbBr的纳米片的光学非活性态。这种方法使我们能够进入暗态并直接确定暗 - 亮分裂，对于最薄的纳米片，该分裂达到22毫电子伏特。由于激子限制减弱，较厚纳米片的分裂明显更小。此外，磁光致发光光谱的形式表明暗态和亮态的布居是非热平衡的，这表明在激子弛豫过程中存在声子瓶颈。
