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Temperature-Induced Phase Transition in 2D Alkylammonium Lead Halide Perovskites: A Molecular Dynamics Study
ACS Nano ( IF 15.8 ) Pub Date : 2024-08-13 , DOI: 10.1021/acsnano.4c03903 Reza Namakian 1 , Maria Alejandra Garzon 1 , Qing Tu 2 , Ali Erdemir 1, 2 , Wei Gao 1, 2
ACS Nano ( IF 15.8 ) Pub Date : 2024-08-13 , DOI: 10.1021/acsnano.4c03903 Reza Namakian 1 , Maria Alejandra Garzon 1 , Qing Tu 2 , Ali Erdemir 1, 2 , Wei Gao 1, 2
Affiliation
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Molecular dynamics simulations are utilized to unravel the temperature-driven phase transition in double-layered butylammonium (BA) methylammonium (MA) lead halide perovskite (BA)2(MA)Pb2I7, which holds great promise for a wide range of optoelectronics and sensor applications. The simulations successfully capture the structural transition from low to high symmetry phases with rising temperatures, consistent with experimental observations. The phase transition is initiated at two critical interfaces: the first is between the inorganic and organic layers, where the melting of N–H bonds in BA leads to a significant reduction in hydrogen bonding between BA and iodides, and the second is at the interface between the top and bottom organic layers, where the melting of the tail bonds in BA triggers the phase transition. Following this, BA cations exhibit a patterned and synchronized motion reminiscent of a conical pendulum, displaying a mix of ordered and disordered behaviors prior to evolving into a completely molten and disordered state. While the melting of BA cations is the primary driver of the phase transition, the rotational dynamics of MA cations also plays a critical role in determining the phase transition temperature, influenced by the BA–MA interaction. Such an interaction alters the polarization patterns of MA cations across the phase transition. In particular, an antiparallel polarization pattern is observed in the low-temperature phase. Additionally, displacive elements of the phase transition are identified in the simulations, characterized by the shear and distortion of the inorganic octahedra. Notably, at lower temperatures, the octahedral distortion follows a bimodal distribution, reflecting significant variations in distortion among octahedra. This variation is attributed to an anisotropic hydrogen bonding network between iodides and BA cations. Our study reveals the phenomena and mechanisms extending beyond the order–disorder transition mechanism, suggesting potential phase engineering through strategic tuning of organic and inorganic components.
中文翻译：
二维烷基铵卤化铅钙钛矿中温度诱导的相变：分子动力学研究
利用分子动力学模拟来揭示双层丁基铵 (BA) 甲基铵 (MA) 卤化铅钙钛矿 (BA) 2 (MA)Pb 2 I 7中温度驱动的相变，这为广泛的光电子学领域带来了巨大的前景和传感器应用。模拟成功地捕获了随着温度升高从低对称性相到高对称性相的结构转变，这与实验观察结果一致。相变在两个关键界面处开始：第一个是无机层和有机层之间，BA 中 N-H 键的熔化导致 BA 和碘化物之间的氢键显着减少，第二个是在界面处顶部和底部有机层之间，BA 尾部键的熔化触发相变。此后，BA 阳离子表现出一种让人想起圆锥摆的图案化和同步运动，在演变成完全熔融和无序状态之前，表现出有序和无序行为的混合。虽然 BA 阳离子的熔化是相变的主要驱动力，但受 BA-MA 相互作用的影响，MA 阳离子的旋转动力学在确定相变温度方面也起着关键作用。这种相互作用改变了 MA 阳离子在相变过程中的极化模式。特别是，在低温相中观察到反平行偏振图案。此外，在模拟中还确定了相变的位移元素，其特征是无机八面体的剪切和变形。 值得注意的是，在较低温度下，八面体畸变遵循双峰分布，反映了八面体之间畸变的显着变化。这种变化归因于碘化物和 BA 阳离子之间的各向异性氢键网络。我们的研究揭示了超越有序-无序转变机制的现象和机制，表明通过有机和无机成分的战略调整来进行潜在的相工程。
更新日期：2024-08-13
中文翻译：
二维烷基铵卤化铅钙钛矿中温度诱导的相变：分子动力学研究
利用分子动力学模拟来揭示双层丁基铵 (BA) 甲基铵 (MA) 卤化铅钙钛矿 (BA) 2 (MA)Pb 2 I 7中温度驱动的相变，这为广泛的光电子学领域带来了巨大的前景和传感器应用。模拟成功地捕获了随着温度升高从低对称性相到高对称性相的结构转变，这与实验观察结果一致。相变在两个关键界面处开始：第一个是无机层和有机层之间，BA 中 N-H 键的熔化导致 BA 和碘化物之间的氢键显着减少，第二个是在界面处顶部和底部有机层之间，BA 尾部键的熔化触发相变。此后，BA 阳离子表现出一种让人想起圆锥摆的图案化和同步运动，在演变成完全熔融和无序状态之前，表现出有序和无序行为的混合。虽然 BA 阳离子的熔化是相变的主要驱动力，但受 BA-MA 相互作用的影响，MA 阳离子的旋转动力学在确定相变温度方面也起着关键作用。这种相互作用改变了 MA 阳离子在相变过程中的极化模式。特别是，在低温相中观察到反平行偏振图案。此外，在模拟中还确定了相变的位移元素，其特征是无机八面体的剪切和变形。 值得注意的是，在较低温度下，八面体畸变遵循双峰分布，反映了八面体之间畸变的显着变化。这种变化归因于碘化物和 BA 阳离子之间的各向异性氢键网络。我们的研究揭示了超越有序-无序转变机制的现象和机制，表明通过有机和无机成分的战略调整来进行潜在的相工程。
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