CAREER: Tracking Charge and Energy Transfer at Buried Organic Interfaces

在这个由化学结构，动力学和机制-A计划支持的项目中，德克萨斯大学奥斯汀分校的Sean Roberts教授和他的学生正在开发新的基于激光的光学工具，该工具能够研究在半导体有机分子组成的薄膜界面处发生的电荷转移过程。这项研究推进了我们对导电分子性质的认识，也可能推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的研究生和本科生的培训提供了一个工具。该项目的主要目标是建立结构-功能关系，以指导两种模型有机半导体（OSC）界面的界面电荷和能量转移：（1）方酸染料：富勒烯异质结，用于分离有机光致发光材料中的电荷，以及（2）硅和铟镓砷（InGaAs）表面，这些表面已被具有单线态裂变能力的并苯分子敏化。为了测量这些界面的电子结构和动力学，Roberts小组正在采用基于界面特定技术的稳态和时间分辨测量，电子和频产生（ESFG）。ESFG允许在OSC界面处选择性地观察能量和电子转移。通过使用这些光谱方法与传统的薄膜表征工具和材料加工方法相结合，可以改变异质结处的分子堆积，该项目允许研究小组建立结构-功能关系，可以提高掩埋OSC界面处的能量转移和电荷分离效率，并可能推进光伏技术。

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.