Tracking single charges in organic semiconductors by surface enhanced Raman scattering

在国家科学基金会化学部分析和表面化学项目的支持下，Lupton教授和他在犹他大学的团队将开发和利用超灵敏光谱技术来揭示有机半导体功能背后的结构和电子性质。将拉曼光谱应用于单个半导体有机分子，可以通过特征振动指纹揭示分子内电荷密度的高度局域变化，从而影响原子间的分离。该项目试图通过振动频率的变化来识别分子电荷的特征。表面增强拉曼散射(SERS)效应大大提高了拉曼光谱的选择性。这种放大应该能够识别出有机发光二极管(OLED)等工作设备中的单个充电事件，从而能够直接跟踪电荷迁移。该项目的独特性源于有机半导体和SERS这两个领域的协同作用。虽然表面增强拉曼光谱是有机半导体研究中的一种新的分析工具，但特别是共轭聚合物最近已被证明是研究表面增强拉曼光谱本身的基本物理的优秀材料。因此，预计该项目将进一步提高SERS的重现性、稳定性、选择性和灵敏度。这项研究的高度跨学科性质需要校内外的一系列合作，为参与该项目的学生提供多才多艺的培训背景。

Prof. Lupton and his group at the University of Utah, with the support of the Analytical and Surface Chemistry Program in the Chemistry Division of the National Science Foundation, will develop and utilize ultra-sensitive spectroscopic techniques to unravel the structural and electronic properties underlying the function of organic semiconductors. By applying Raman spectroscopy to single semiconducting organic molecules, highly local changes in the intramolecular charge density which affects the interatomic separation can be revealed through the characteristic vibrational fingerprints. The project seeks to identify signatures of molecular charging through a change in vibrational frequency. The surface enhanced Raman scattering (SERS) effect dramatically amplifies the selectivity of Raman spectroscopy. This amplification should make it possible to pick out individual charging events within a working device such as an organic light-emitting diode (OLED), enabling a direct tracking of charge migration.The project's uniqueness stems from a synergy between the two fields of organic semiconductors and SERS. While SERS is new as an analytical tool in the study of organic semiconductors, conjugated polymers in particular have recently proven to be excellent materials for the investigation of the underlying physics of SERS itself. Further improvements to the reproducibility, stability, selectivity and sensitivity of SERS are therefore anticipated to come out of this project. The highly interdisciplinary nature of the research necessitates a range of collaborations on and off campus, providing a versatile training background for the students engaged with the venture.