光致振动驱动卤化铅超导体的超快结构畸变
Photoinduced Vibrations Drive Ultrafast Structural Distortion in Lead Halide Perovskite
摘要：
有机-无机钙钛矿在光电子学领域的应用前景广阔。这类材料的成功取决于各种潜在微观现象之间的复杂相互作用。假设光激发后的有机阳离子和无机亚晶格的结构动力学对材料性质具有直接影响，从而影响整体器件性能。在这里，我们使用二维（2D）电子光谱来揭示脉冲激发振动模式的甲基铵（MA）碘化铅钙钛矿，驱动光激发后的结构畸变。对测量数据的振动分析使我们能够直接监测MA阳离子的振动运动的时间演化以及无机亚晶格的振动凝聚。小波分析所观察到的振动相干揭示了这两种类型的声子之间的相互作用。它揭示了在~300 fs内MA阳离子的自由振动运动的相干产生，这是由无机亚晶格的骨架运动的相干演化所补充的。我们采用含时密度泛函理论（TDDFT）研究了MA阳离子和无机亚晶格在光激发过程中的原子运动。的TDDFT计算支持我们的实验观测的相干产生的librational运动的MA阳离子和突出的重要性的MA阳离子和无机亚晶格之间的非谐相互作用。我们的计算预测转移的光致振动相干从MA阳离子的无机亚晶格，这驱动骨架运动，形成一个极化态，导致长寿命的载流子。这项工作可能会为下一代太阳能电池材料带来新的设计原理。
英文摘要：
Organic-inorganic perovskites have shown great promise towards their application in optoelectronics. The success of this class of material is dictated by the complex interplay between various underlying microscopic phenomena. The structural dynamics of organic cations and the inorganic sublattice after photoexcitation is hypothesized to have a direct effect on the material properties, thereby affecting the overall device performance. Here, we use two-dimensional (2D) electronic spectroscopy to reveal impulsively excited vibrational modes of methylammonium (MA) lead iodide perovskite, which drive the structural distortion after photoexcitation. The vibrational analysis of the measured data allows us to directly monitor the time evolution of the librational motion of the MA cation along with the vibrational coherences of inorganic sublattice. Wavelet analysis of the observed vibrational coherences uncovers the interplay between these two types of phonons. It reveals the coherent generation of the librational motion of the MA cation within ~300 fs, which is complemented by the coherent evolution of the skeletal motion of the inorganic sublattice. We have employed time-dependent density functional theory (TDDFT) to study the atomic motion of the MA cation and the inorganic sublattice during the process of photoexcitation. The TDDFT calculations support our experimental observations of the coherent generation of librational motions in the MA cation and highlight the importance of the anharmonic interaction between the MA cation and the inorganic sublattice. Our calculations predict the transfer of the photoinduced vibrational coherence from the MA cation to the inorganic sublattice, which drives the skeleton motion to form a polaronic state leading to long lifetimes of the charge carriers. This work may lead to novel design principles for next generation of solar cell materials.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
