论文标题
通过依赖能量的光激发卤化物钙壶的可调照片小写
Tunable photostriction of halide perovskites through energy dependent photoexcitation
论文作者
论文摘要
卤化物钙钛矿表现出巨大的照片编写，即照明时的体积或形状变化。然而，这种现象的微观起源尚不清楚，并且有有关光诱导的晶格扩张和收缩的实验报道。在本文中，我们基于第一原理计算和分子轨道理论建立了一种通用方法，该方法基于其电子带的轨道特征在Fermi级别附近提供了绝缘子中的光述微观图片。对于高途径钙钛矿，我们发现不同的价状态具有不同的键合特征，从而导致键的增强或削弱，具体取决于光激发能量。总体趋势是，在低激发能量下，光引起晶格收缩，而巨型晶格的扩张发生在高激发能，从而使实验报告合理化。
Halide perovskites exhibit giant photostriction, that is, volume or shape changes upon illumination. However, the microscopic origin of this phenomenon remains unclear and there are experimental reports of both light-induced lattice expansion and contraction. In this paper we establish a general method, based on first-principles calculations and molecular orbital theory, which provides a microscopic picture of photostriction in insulators based on the orbital characters of their electronic bands near the Fermi level. For lead-halide perovskites, we find that different valence states have different bonding characters, leading to opposing strengthening or weakening of bonds depending on the photoexcitation energy. The overall trend is that light induces lattice contraction at low excitation energies, while giant lattice expansion occurs at high excitation energies, rationalizing experimental reports.
