CAREER: Tracking Charge and Energy Transfer at Buried Organic Interfaces

University Of Texas At Austin, Austin TX

Investigators

Abstract

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.