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Good Vibrations: Locking of Octahedral Tilting in Mixed-Cation Iodide Perovskites for Solar Cells
ACS Energy Letters ( IF 22.0 ) Pub Date : 2017-09-20 00:00:00 , DOI: 10.1021/acsenergylett.7b00729
Dibyajyoti Ghosh 1 , Philip Walsh Atkins 2 , M. Saiful Islam 2 , Alison B. Walker 1 , Christopher Eames 2
Affiliation  

Metal halide perovskite solar cells have rapidly emerged as leading contenders in photovoltaic technology. Compositions with a mixture of cation species on the A-site show the best performance and have higher stability. However, the underlying fundamentals of such an enhancement are not fully understood. Here, we investigate the local structures and dynamics of mixed A-cation compositions. We show that substitution of low concentrations of smaller cations on the A-site in formamidimium lead iodide (CH(NH2)2PbI3) results in a global “locking” of the PbI6 octahedra tilting. In the locked structure the octahedra tilt at a larger angle but undergo a much reduced amplitude of rocking motion. A key impact of this feature is that the rotational or tumbling motion of the CH(NH2)2+ molecular ion in a locked cage is severely restricted. We discuss the impact of locking on the photovoltaic performance and stability.

中文翻译:

良好的振动:太阳能电池混合阳离子碘化物钙钛矿中八面体倾斜的锁定

金属卤化物钙钛矿太阳能电池已迅速成为光伏技术的主要竞争者。在A位置混合了阳离子物质的组合物表现出最佳性能,并具有更高的稳定性。但是,这种增强的基本原理尚未完全理解。在这里,我们研究了混合的A阳离子组成的局部结构和动力学。我们表明,在甲ami碘化铅(CH(NH 22 PbI 3)的A位上替换低浓度的较小浓度阳离子会导致PbI 6的整体“锁定”八面体倾斜。在锁定结构中,八面体以较大的角度倾斜,但摇摆运动的幅度大大降低。此功能的关键影响在于,锁定笼中的CH(NH 22 +分子离子的旋转或翻滚运动受到严格限制。我们讨论了锁定对光伏性能和稳定性的影响。
更新日期:2017-09-20
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