有机阳离子在碘化甲脒铅钙钛矿中的旋转动力学。
Rotational Dynamics of Organic Cations in Formamidinium Lead Iodide Perovskites.
机构信息
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble cedex 9, France.
出版信息
J Phys Chem Lett. 2023 Mar 23;14(11):2784-2791. doi: 10.1021/acs.jpclett.3c00185. Epub 2023 Mar 10.
We report results from quasi-elastic neutron scattering studies on the rotational dynamics of formamidinium (HC[NH], FA) and methylammonium (CHNH, MA) cations in FAMAPbI with = 0 and 0.4 and compare it to the dynamics in MAPbI. For FAPbI, the FA cation dynamics evolve from nearly isotropic rotations in the high-temperature ( > 285 K) cubic phase through reorientations between preferred orientations in the intermediate-temperature tetragonal phase (140 K < ⩽ 285 K) to an even more complex dynamics, due to a disordered arrangement of the FA cations, in the low-temperature tetragonal phase ( ⩽ 140 K). For FAMAPbI, the dynamics of the respective organic cations evolve from a relatively similar behavior to FAPbI and MAPbI at room temperature to a different behavior in the lower-temperature phases where the MA cation dynamics are a factor of 50 faster as compared to those of MAPbI. This insight suggests that tuning the MA/FA cation ratio may be a promising approach to tailoring the dynamics and, in effect, optical properties of FAMAPbI.
我们报告了准弹性中子散射研究的结果，该研究针对的是在 = 0 和 0.4 时，FAMAPbI 中 formamidinium（HC[NH]，FA）和 methylammonium（CHNH，MA）阳离子的旋转动力学，并将其与 MAPbI 的动力学进行了比较。对于 FAPbI，FA 阳离子的动力学从高温（ > 285 K）立方相的近各向同性旋转通过中间温度四方相（140 K < ⩽ 285 K）中的优先取向重定向演变，再到由于 FA 阳离子的无序排列，在低温四方相（ ⩽ 140 K）中甚至更复杂的动力学。对于 FAMAPbI，各有机阳离子的动力学从室温下与 FAPbI 和 MAPbI 相对相似的行为演变为低温相中的不同行为，其中 MA 阳离子的动力学比 MAPbI 快 50 倍。这一见解表明，调整 MA/FA 阳离子比例可能是一种有前途的方法，可以调整 FAMAPbI 的动力学，从而调整其光学性质。
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