发表机构
Brigham Young University; University of Illinois at Urbana-Champaign; University of Iowa（杨百翰大学; 伊利诺伊大学厄巴纳-香槟分校; 爱荷华大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对层状HOIP化合物中激子约化质量与结构畸变的因果/关联问题，该研究利用群表示理论分解结构畸变的对称模式，结合密度泛函理论独立调控各模式振幅，明确了赤道/顶端卤原子横向位移对激子约化质量的相反调控作用，为激子工程提供新途径。
AI 中文摘要
近期研究报道，在一系列9种单层（二维）金属卤化物钙钛矿（HOIP）化合物中，激子约化质量（$\mu$）与框架畸变存在强相关性。具体而言，观察到$\mu$随PbI₄八面体绕面内轴的交替倾斜同步增大。本研究利用群表示理论，将观测到的框架畸变分解为常见高对称母体框架的位移对称模式。我们发现，这9种畸变框架均涉及相同6种对称模式的线性组合，据报道这些模式对大量HOIP化合物的框架畸变均有贡献。研究表明，这些模式对能带结构的影响高度相关。为区分因果关系与相关性，我们独立改变每种模式的振幅，并采用密度泛函理论确定所得电子能带结构，从中提取$\mu$。结果显示，赤道卤原子的键横向位移会增大$\mu$，而顶端卤原子的键横向位移会减小$\mu$；键轴向位移对$\mu$几乎无影响。本研究结果揭示了三种新的结构-性能关系，为层状钙钛矿材料的激子工程提供了极具前景的新途径。
英文摘要
Reduced exciton mass ($μ$) was recently reported to correlate strongly with a framework distortion in a series of nine single-layer (2D) metal-halide perovskite (HOIP) compounds. Specifically, $μ$ was observed to increase in tandem with an alternating PbI4 octahedral tilt about an in-plane axis. In this work, we use group representation theory to decompose the observed framework distortions into displacive symmetry modes of a common high-symmetry parent framework. We find that all nine distorted frameworks involve linear combinations of the same six symmetry modes, which have been reported to contribute to the framework distortions of a wide range of HOIP compounds. We show that these modes have highly correlated impacts on the band structure. To differentiate causation from correlation, we vary the amplitude of each mode independently and use density-functional theory to determine the resulting electronic band structures, from which $μ$ is extracted. We find that bond-transverse displacements of the equatorial halide atoms increase $μ$, while bond-transverse displacements of the apical halide atoms decrease it. Bond-axis displacements appear to have little or no effect on $μ$. Our results demonstrate three new structure-property relationships, revealing a promising new avenue for exciton engineering in layered perovskite materials.
Comments27 pages, 14 figures. For associated SI information, see DOI 10.5281/zenodo.22261753
