LP2N, Université de Bordeaux , Talence F-33405, France.
LP2N, Institut d'Optique and CNRS , Talence F-33405, France.
Nano Lett. 2017 May 10;17(5):2895-2901. doi: 10.1021/acs.nanolett.7b00064. Epub 2017 Apr 24.
Revealing the crystal structure of lead halide perovskite nanocrystals is essential for the optimization of stability of these emerging materials in applications such as solar cells, photodetectors, and light-emitting devices. We use magneto-photoluminescence spectroscopy of individual perovskite CsPbBr nanocrystals as a unique tool to determine their crystal structure, which imprints distinct signatures in the excitonic sublevels of charge complexes at low temperatures. At zero magnetic field, the identification of two classes of photoluminescence spectra, displaying either two or three sublevels in their exciton fine structure, shows evidence for the existence of two crystalline structures, namely tetragonal D and orthorhombic D phases. Magnetic field shifts, splitting, and coupling of the sublevels provide a determination of the diamagnetic coefficient and valuable information on the exciton g-factor and its anisotropic character. Moreover, this spectroscopic study reveals the optical properties of charged excitons and allows the extraction of the electron and hole g-factors for perovskite systems.
揭示卤化铅钙钛矿纳米晶体的晶体结构对于优化这些新兴材料在太阳能电池、光电探测器和发光器件等应用中的稳定性至关重要。我们使用单个钙钛矿 CsPbBr 纳米晶体的磁光荧光光谱作为一种独特的工具来确定它们的晶体结构，这种晶体结构在低温下的电荷复合物的激子亚能级中留下了明显的特征。在零磁场下，两种类别的光致发光光谱的识别，它们在激子精细结构中显示出两个或三个亚能级，这表明存在两种晶体结构，即四方 D 和正交 D 相。亚能级的磁场位移、分裂和耦合提供了对反磁性系数的确定，并提供了关于激子 g 因子及其各向异性特征的有价值的信息。此外，这项光谱研究揭示了带电激子的光学性质，并允许提取钙钛矿体系的电子和空穴 g 因子。
