Symmetry, Dynamics, and Defects in Methylammonium Lead Halide Perovskites
Symmetry, Dynamics, and Defects in Methylammonium Lead Halide Perovskites
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DOI：
10.1021/acs.jpclett.6b02542
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发表时间：
2017-01-05
影响因子：
5.7
通讯作者：
Kentgens, Arno P. M.
中科院分区：
文献类型：
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作者：
Franssen, Wouter M. J.;van Es, Sverre G. D.;Kentgens, Arno P. M.
为了更好地理解甲基铵卤化铅钙钛矿的结构和动力学，我们对CH 3 NH3 PbI 3在四方相和立方相中进行了NMR、NQR和DFT研究。结果表明，四方相的空间群为非极性I4/mcm。高度动态的甲基铵部分没有显示出在接近立方相的温度下靠近c轴的C-N键的额外取向的发生的迹象。晶体质量的影响被证明是影响的N-14 NMR和I-127 NQR光谱，和高温退火的缺陷的影响，可以观察到。发现冷却时Pb-202 NMR信号的T-2弛豫时间的强烈增加，并且是在室温下PbI 6八面体中的慢运动的指示。这些结果有助于了解甲基铵铅卤化物的结构，并使这些材料中的缺陷的进一步研究。
In order to better understand the structure and dynamics of methylammonium lead halide perovskites, we performed NMR, NQR, and DFT studies of CH3NH3PbI3 in the tetragonal and cubic phase. Our results indicate that the space group of the tetragonal phase is the nonpolar I4/mcm. The highly dynamic methylammonium moiety shows no indication of the occurrence of additional orientations of the C-N bond close to the c-axis at temperatures approaching the cubic phase. Crystal quality effects are shown to influence the N-14 NMR and I-127 NQR spectra, and the effects of high-temperature annealing on defects can be observed. A strong increase in T-2 relaxation time of the Pb-202 NMR signal on cooling is found, and is an indication of slow motions in the PbI6 octahedra at room temperature. These results aid in the understanding of the structure of methylammonium lead halides and enable further studies of defects in these materials.