Schrenker Nadine J, Braeckevelt Tom, De Backer Annick, Livakas Nikolaos, Yu Chu-Ping, Friedrich Thomas, Roeffaers Maarten B J, Hofkens Johan, Verbeeck Johan, Manna Liberato, Van Speybroeck Veronique, Van Aert Sandra, Bals Sara
Electron Microscopy for Materials Science (EMAT), University of Antwerp, 2020 Antwerp, Belgium.
NANOlab Center of Excellence, University of Antwerp, 2020 Antwerp, Belgium.
Nano Lett. 2024 Sep 4;24(35):10936-10942. doi: 10.1021/acs.nanolett.4c02811. Epub 2024 Aug 20.
Metal halide perovskites (MHP) are highly promising semiconductors. In this study, we focus on FAPbBr nanocrystals, which are of great interest for green light-emitting diodes. Structural parameters significantly impact the properties of MHPs and are linked to phase instability, which hampers long-term applications. Clearly, there is a need for local and precise characterization techniques at the atomic scale, such as transmission electron microscopy. Because of the high electron beam sensitivity of MHPs, these investigations are extremely challenging. Here, we applied a low-dose method based on four-dimensional scanning transmission electron microscopy. We quantified the observed elongation of the projections of the Br atomic columns, suggesting an alternation in the position of the Br atoms perpendicular to the Pb-Br-Pb bonds. Together with molecular dynamics simulations, these results remarkably reveal local distortions in an on-average cubic structure. Additionally, this study provides an approach to prospectively investigating the fundamental degradation mechanisms of MHPs.
金属卤化物钙钛矿（MHP）是极具前景的半导体。在本研究中，我们聚焦于对绿色发光二极管极具吸引力的FAPbBr纳米晶体。结构参数对MHP的性质有显著影响，且与相不稳定性相关，这阻碍了其长期应用。显然，需要在原子尺度上采用局部和精确的表征技术，如透射电子显微镜。由于MHP对电子束的高灵敏度，这些研究极具挑战性。在此，我们应用了基于四维扫描透射电子显微镜的低剂量方法。我们对观察到的Br原子列投影的伸长进行了量化，表明Br原子在垂直于Pb - Br - Pb键的位置发生了交替变化。结合分子动力学模拟，这些结果显著揭示了平均立方结构中的局部畸变。此外，本研究提供了一种前瞻性研究MHP基本降解机制的方法。
