2012年7月6日 Xi Lin （Assistant Professor，Department of Mechanical Engineering Division of Materials Science and Engineering，Boston University)作学术报告。
时间：7月6日上午10:30 地点：卢嘉锡楼202报告厅
摘要：The structural-property relationship of materials systems such that specific materials properties may be achieved via molecular design. Emergence of fascinating applications using pi-conjugated oligomers and polymers in light-emitting devices and photovoltaics requires precise control and flexible tuning of optical bandgaps to effectively cover the visible and other parts of the solar spectrum. In this talk, we report the predicted optical bandgaps for nearly 200 pi-conjugated systems using our recently developed adapted Su-Schrieffer-Heeger Hamiltonian that incorporates the many-body correlations into universal electron-phonon coupling constants.
Our predicted optical bandgaps contain an average systematic error of -0.043 eV with the standard deviation being 0.16 eV as compared to the corresponding experimental measurements, far exceeding the accuracy of the time-dependent density functional theory. A few fundamental insights are extracted from these calculations and applied to guide the optical bandgap design, against ambiguous chemical intuitions or misconceptions widely assumed in the community. New pi-conjugated structures of the targeted 1.2 eV optical bandgap are identified, which are suitable for the polymer solar cells and small-molecule crystalline electronics.
Short Bio: Xi Lin received his B.S. degree at Peking University and Ph.D. degree at Massachusetts Institute of Technology, both in Chemistry. Lin is currently an Assistant Professor in Mechanical Engineering and Materials Science and Engineering at Boston University. His research interest is focused on the soliton theory of conducting polymers and the glass transition theory.
