Aebli Marcel, Piveteau Laura, Nazarenko Olga, Benin Bogdan M, Krieg Franziska, Verel René, Kovalenko Maksym V
Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, CH-8093, Switzerland.
Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse 129, CH-8600, Switzerland.
Sci Rep. 2020 May 19;10(1):8229. doi: 10.1038/s41598-020-65071-4.
Understanding the structure and dynamics of newcomer optoelectronic materials - lead halide perovskites APbX [A = Cs, methylammonium (CHNH, MA), formamidinium (CH(NH), FA); X = Cl, Br, I] - has been a major research thrust. In this work, new insights could be gained by using Pb solid-state nuclear magnetic resonance (NMR) spectroscopy at variable temperatures between 100 and 300 K. The existence of scalar couplings J of ca. 400 Hz and J of ca. 2.3 kHz could be confirmed for MAPbX and CsPbX. Diverse and fast structure dynamics, including rotations of A-cations, harmonic and anharmonic vibrations of the lead-halide framework and ionic mobility, affect the resolution of the coupling pattern. Pb NMR can therefore be used to detect the structural disorder and phase transitions. Furthermore, by comparing bulk and nanocrystalline CsPbBr a greater structural disorder of the PbBr-octahedra had been confirmed in a nanoscale counterpart, not readily captured by diffraction-based techniques.
理解新型光电子材料——卤化铅钙钛矿APbX[A = Cs、甲胺（CH₃NH₂，MA）、甲脒（CH(NH)₂，FA）；X = Cl、Br、I]的结构和动力学一直是主要研究方向。在这项工作中，通过在100至300 K的可变温度下使用铅固态核磁共振（NMR）光谱可以获得新的见解。对于MAPbX和CsPbX，可以确认约400 Hz的标量耦合J和约2.3 kHz的J的存在。多种快速的结构动力学，包括A阳离子的旋转、卤化铅框架的谐波和非谐波振动以及离子迁移率，都会影响耦合模式的分辨率。因此，Pb NMR可用于检测结构无序和相变。此外，通过比较块状和纳米晶CsPbBr，已证实在纳米级对应物中PbBr八面体的结构无序程度更大，这是基于衍射的技术难以捕捉到的。
