Design, Synthesis, and Properties of Open-Shell Organic Semiconductors

William Marsh Rice University, Houston TX

Investigators

Abstract

Professor Eilaf Egap of Emory University is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry to develop strategies for the preparation and investigation of open-shell conjugated oligomers and polymers. The chemical and physiochemical properties of these materials and the way they respond upon interactions with light are investigated. The goal is to understand and be able to manipulate the factors that influence their organic semiconducting properties. Organic semiconductors are used in a range of technologies such as light-emitting diodes, sensors, photovoltaics and integrated electronic circuits. The results of this research project are expected to directly impact these technologies by reducing power consumption, improving sensitivity, and enhancing data and energy storage. During the course of conducting this project, students from underrepresented minorities and undergraduate students from local historically-black colleges and universities are involved in science research activities related to this project. This is accomplished through an eight-week summer research and mentoring program and a joint seminar series in the areas of physical and materials chemistry. The students are actively involved in research and in planning the seminar series as a motivation to keep them interested and fully engaged in STEM areas. This research program advances strategies for the synthesis and characterization of organic open-shell conjugated oligomeric and polymeric semiconductor materials based on polythiophene and quinoidal backbones, and including stable long-lived radicals as spin resources. The chemical and photophysical properties of these materials, including molecular packing and the dynamics and kinetics of electron spins, are investigated. The materials are characterized using a variety of techniques, including ultrafast transient spectroscopy and scanning probe microscopy. An important goal of this project is to understand the structural and physical factors that control photo-induced spin-alignment and spin-polarization and to determine the molecular packing, structural orientation and topology factors which influence hybrid states and spin-exchange in organic oligomer/polymer semiconductors. Another goal is to understand and establish design rules for modulating and predicting excited-states energy levels. Theoretical calculations and computational modelling are used to help guide the choice of targets and to support the spin polarization and the excited states studies.