2015 New Investigator Grant
Mark Chen, Ph.D. Assistant Professor, Department of Chemistry, Lehigh University
Development of Molecular Biradicaloids for Organic Electronic Materials
As electronics have become ubiquitous in our daily lives, there is a drive to develop devices with higher energy efficiency and greater portability. Such development begins with the investigation of new electronic materials. Recently organic carbon-based compounds have emerged as a promising material in electronic devices like light-emitting diodes, transistors, and solar cells. Compared to inorganic silicon-based materials, organics rely on abundant carbon sources and are often lightweight, less energy-intensive to manufacture, and exhibit properties that are easily tailored through synthetic organic chemistry. However, current organic materials suffer from poor electronic device performance that often stems from meager charge transport efficiencies. Towards enhancing charge transport, our proposed work will take an approach towards molecular design that is fundamentally different from many current materials synthesis efforts that have focused on subtle structural derivatization. Here we propose a strategy for synthesizing molecular biradicaloids that can be explored for use as organic electronic materials. These molecules employ phenalenyl groups to achieve biradical character and greater charge delocalization for environmental stability. Unlike conventional organic semiconductors that display strong intramolecular pairing of electrons, biradicaloids exhibit weak intramolecular pairing, but significant intermolecular electronic coupling. This intermolecular spinspin coupling directly addresses the challenges in current organic electronic materials – where intermolecular charge hopping is rate-limiting. Despite these promising properties molecular biradicaloids have remained unexplored as semiconductors, likely because lengthy syntheses make such materials studies prohibitive. We will overcome this challenge by employing a synthetic strategy that requires half the number of steps as previous reports, and eases structural diversification for tuning electronic and solid-state properties. Our aim is to elucidate important structure-property relationships, especially regarding the materials’ stability and charge transport properties. If successful, our biradicaloids will demonstrate unprecedented efficiencies in charge transport and a fundamentally new design principle in the field of organic electronic materials.