CAREER: Tracking Charge and Energy Transfer at Buried Organic Interfaces

在化学结构、动力学和机制计划的支持下，德克萨斯大学奥斯汀分校的肖恩·罗伯茨教授和他的学生正在开发新的基于激光的光学工具，使研究发生在半导体有机分子组成的薄膜界面上的电荷转移过程成为可能。这项研究促进了我们对导电分子性质的认识，也可能促进这类分子在太阳能技术中的应用。该项目为化学、光学物理和材料科学方面的研究生和本科生提供了一种培训工具。这个项目的主要目标是建立结构-功能关系来指导两个有机半导体(OSC)模型界面上的电荷和能量转移：(1)方酸染料：用于在有机光伏中分离电荷的富勒烯异质结，以及(2)已被单态裂变可裂变烯分子敏化的硅和铟-镓-砷(InGaAs)表面。为了测量这些界面的电子结构和动态，Roberts团队采用了基于特定界面技术的稳态和时间分辨测量，即电子和频产生(ESFG)。ESFG允许选择性地观察OSC界面上的能量和电子转移。通过将这些光谱方法与可以改变异质结分子堆积的传统薄膜表征工具和材料处理方法结合使用，该项目使研究小组能够建立结构-功能关系，从而提高埋入OSC界面的能量转移和电荷分离的效率，并潜在地促进光伏技术的发展。

In this project supported by the Chemical Structure, Dynamics and Mechanisms-A Program, Professor Sean Roberts and his students at the University of Texas at Austin are developing new laser-based optical tools which enable the study of electric charge transfer processes occurring at the interfaces of films composed of semiconducting organic molecules. The research advances our knowledge about the properties of electrically conductive molecules, and may also advance the application of this class of molecules in solar energy technology. The project provides a vehicle for the training of graduate and undergraduate students in chemistry, optical physics, and materials science. A significant part of the undergraduates' involvement occurs through a collaboration with Austin Community College.The primary goal of this project is to establish the structure-function relationships that guide interfacial charge and energy transfer at two model organic semiconducting (OSC) interfaces: (1) squaraine dye:fullerene heterojunctions used to separate charge in organic photovoltaics, and (2) silicon and Indium-Gallium-Arsenic (InGaAs) surfaces that have been sensitized with singlet fission-capable acene molecules. To measure the electronic structure and dynamics of these interfaces, the Roberts groups is employing steady-state and time-resolved measurements based on an interface-specific technique, Electronic Sum Frequency Generation (ESFG). ESFG allows for selective viewing of energy and electron transfer at OSC interfaces. By using these spectroscopic methods in conjunction with conventional thin film characterization tools and material processing methods that can alter molecular packing at heterojunctions, the project allows the research group to establish structure-function relationships that can improve the efficiency of energy transfer and charge separation at buried OSC interfaces and potentially advances photovoltaic technologies.