报告题目 (Title)：分子电子给体及受体：超越传统有机半导体掺杂调控
报告人 (Speaker)：Norbert Koch教授（柏林洪堡大学）
报告时间 (Time)：2026年4月16日（周四）下午3:00-5:00
报告地点 (Place)：校本部 G313
邀请人 (Inviter)：金腾宇、尹鑫茂
主办部门：理学院物理系
摘要 (Abstract)：
Strong molecular electron donors and acceptors enable the controlled n- and p-type doping of organic semiconductors. Fundamental processes involved in this doping will be introduced, including the phenomenon of “double doping”, where one dopant can generate even two charge carriers. Such molecular dopants have been suggested to also facilitate doping of inorganic two-dimensional (2D) semiconductors, such as monolayer MoS2. However, the charge transfer processes between the dopants and the 2D semiconductor depend markedly on the nature of the mechanical support (substrate) of the entire structure, and doping may only be mimicked. Based on these findings for monolayer MoS2 and by exploiting a substrate-to-molecule charge transfer mechanism, it will be shown by photoelectron spectroscopy how a giant Stark effect can be induced in bilayer MoS2, thus lifting the energy level degeneracy of the two layers. Eventually, this approach could allow the realization of an excitonic insulator state. Finally, the interfacial electronic energy level alignment between a metal halide perovskite and a molecular electron acceptor, as encountered in next-generation solar cells, will be investigated with operando photoelectron spectroscopy. In contrast to text-book knowledge, we find that the energy levels undergo a huge re-alignment between dark and visible light illumination conditions. This new phenomenon might thus relax the stringent materials selection criteria for improving solar cell performance.
