講座編號：jz-yjsb-2022-y012
講座題目：Band Engineering in Two-Dimensional Covalent Organic Frameworks
主 講 人：倪曉娟 博士 美國亞利桑那大學博士后
講座時間：2022年4月22日（星期五）上午11:00
講座地點：騰訊會議，會議ID：256 844 581
參加對象：人工智能學院師生、對報告感興趣的師生
主辦單位：人工智能學院、研究生院
主講人簡介：
倪曉娟博士于2020年在美國猶他大學獲得材料科學與工程專業博士學位，導師為猶他大學榮譽教授（distinguished professor）Prof. Liu Feng（2015-2021年Physical Review Letters期刊Divisional Associate Editor）。倪曉娟博士目前為美國亞利桑那大學博士后，合作導師為有機太陽能電池領域知名專家Jean-Luc Brédas教授。倪博士的研究方向是金屬-有機和共價-有機框架的電子、磁性和拓撲性質，以及用于電子和自旋電子應用的拓撲材料，迄今已在Materials Horizon、Chemistry Materials、Physical Review B等國際知名期刊上發表了20多篇同行評議的研究文章。獲得的獎項包括猶他大學工程學院最佳博士論文獎等，多次參加美國物理學會APS報告。
主講內容：
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)