讲座编号：jz-yjsb-2022-y012

讲座题目：Band Engineering in Two-Dimensional Covalent Organic Frameworks

主 讲 人：倪晓娟 博士 美国亚利桑那大学博士后

讲座时间：2022年4月22日（星期五）上午11:00

讲座地点：腾讯会议，会议ID：256 844 581

参加对象：人工智能学院师生、对报告感兴趣的师生

主办单位：人工智能学院、研究生院

主讲人简介：

倪晓娟博士于2020年在美国犹他大学获得材料科学与工程专业博士学位，导师为犹他大学荣誉教授（distinguished professor）Prof. Liu Feng（2015-2021年Physical Review Letters期刊Divisional Associate Editor）。倪晓娟博士目前为美国亚利桑那大学博士后，合作导师为有机太阳能电池领域知名专家Jean-Luc Brédas教授。倪博士的研究方向是金属-有机和共价-有机框架的电子、磁性和拓扑性质，以及用于电子和自旋电子应用的拓扑材料，迄今已在Materials Horizon、Chemistry Materials、Physical Review B等国际知名期刊上发表了20多篇同行评议的研究文章。获得的奖项包括犹他大学工程学院最佳博士论文奖等，多次参加美国物理学会APS报告。

主讲内容：

Two-dimensional covalent organic frameworks (2D-COFs), also referred to as 2D polymer networks, display unusual electronic-structure characteristics, which can significantly enrich and broaden the fields of electronics and spintronics. In this presentation, my objective is to lay the groundwork for the conceptual description of the fundamental relationships among the COF electronic structures, the symmetries of their 2D lattices, and the frontier molecular orbitals (MOs) of their core and linker components. We focus on monolayers of hexagonal COFs and use tight-binding model analyses to highlight the critical role of the frontier-MO symmetry, in addition to lattice symmetry, in determining the nature of the electronic bands near the Fermi level. We rationalize the intriguing feature that, when the core unit has degenerate highest occupied MOs [or lowest unoccupied MOs], the COF highest valence band [or lowest conduction band] is flat but degenerate with a dispersive band at a high-symmetry point of the Brillouin zone; the consequences of having such band characteristics are briefly described. Multi-layer and bulk 2D COFs are found to maintain the salient features of the monolayer electronic structures albeit with a reduced bandgap due to the interlayer coupling. This study is thus meant to provide an effective framework for the engineering of flat and Dirac bands in 2D polymer networks. (Materials Horizons 9, 88-98, 2022)