Hammarberg Susanna, Marçal Lucas Atila Bernardes, Lamers Nils, Zhang Zhaojun, Chen Huaiyu, Björling Alexander, Wallentin Jesper
Synchrotron Radiation Research and NanoLund, Lund University, Box 118, Lund 22100, Sweden.
MAX IV Laboratory, Lund University, Lund 22100, Sweden.
ACS Appl Nano Mater. 2023 Sep 21;6(19):17698-17705. doi: 10.1021/acsanm.3c02978. eCollection 2023 Oct 13.
Metal halide perovskites (MHPs) have garnered significant interest as promising candidates for nanoscale optoelectronic applications due to their excellent optical properties. Axially heterostructured CsPbBr-CsPb(BrCl) nanowires can be produced by localized anion exchange of pregrown CsPbBr nanowires. However, characterizing such heterostructures with sufficient strain and real space resolution is challenging. Here, we use nanofocused scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with a 60 nm beam to investigate a heterostructured MHP nanowire as well as a reference CsPbBr nanowire. The nano-XRD approach gives spatially resolved maps of composition, lattice spacing, and lattice tilt. Both the reference and exchanged nanowire show signs of diverse types of ferroelastic domains, as revealed by the tilt maps. The chlorinated segment shows an average Cl composition of = 66 and = 70% as measured by XRD and XRF, respectively. The XRD measurements give a much more consistent result than the XRF ones. These findings are consistent with photoluminescence measurements, showing = 73%. The nominally unexchanged segment also has a small concentration of Cl, as observed with all three methods, which we attribute to diffusion after processing. These results highlight the need to prevent such unwanted processes in order to fabricate optoelectronic devices based on MHP heterostructures.
金属卤化物钙钛矿（MHP）因其优异的光学性能，作为纳米级光电器件应用的有前途的候选材料而备受关注。通过对预生长的CsPbBr纳米线进行局部阴离子交换，可以制备轴向异质结构的CsPbBr-CsPb(BrCl)纳米线。然而，以足够的应变和实空间分辨率表征这种异质结构具有挑战性。在这里，我们使用纳米聚焦扫描X射线衍射（XRD）和60纳米束的X射线荧光（XRF）来研究异质结构的MHP纳米线以及参考CsPbBr纳米线。纳米XRD方法给出了成分、晶格间距和晶格倾斜的空间分辨图谱。如倾斜图谱所示，参考纳米线和交换后的纳米线都显示出不同类型的铁弹畴的迹象。通过XRD和XRF测量，氯化段的平均Cl组成分别为 = 66%和 = 70%。XRD测量结果比XRF测量结果更一致。这些发现与光致发光测量结果一致，显示为 = 73%。用所有三种方法观察到，名义上未交换的段也有少量的Cl，我们将其归因于加工后的扩散。这些结果强调了为了制造基于MHP异质结构的光电器件而防止此类不必要过程的必要性。
