Collaborative Research: Modular Design of Cross-Conjugated Organic Semiconductors

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Malika Jeffries-EL of Iowa State University is funded by the Macromolecular, Supramolecular and Nanochemistry Program for collaborative research involving a team of scientists from both Iowa State and North Georgia College. The team is developing new electronics materials that are organic, meaning they are made from carbon-based molecules rather than the more commonly used inorganic materials, such as those based on silicon or germanium. In addition to their relative abundance, these organic materials have much lower fabrication costs and provide a range of properties not found in the inorganic substances. In this project, a combination of synthesis, theoretical calculations and physical measurement studies are being combined to design and fabricate working electronic devices. This work is having a broad impact not only on the electronics industry, but also by providing an interdisciplinary research experience for both undergraduate and graduate students, which fosters an interest in chemistry through a creative outreach effort targeting female and underrepresented minority students at all educational levels.This project focuses on developing new cross-conjugated organic semiconductors for use in organic light emitting diodes and photovoltaic cells. In particular, novel cross-conjugated oligomers comprised of the robust benzobisoxazole (BBO) moiety are being studied. BBO is used as the electron-deficient building block since it is a unique cross-conjugated ring system that can be coupled either through the oxazole rings or through the central benzene ring, producing substances with different properties. The group is synthesizing materials with perpendicular conjugation axes because they have spatially segregated frontier molecular orbitals. This provides a means for semi-independent tuning of either the lowest unoccupied molecular orbital (LUMO) or highest occupied molecular orbital (HOMO). The benefits of the approach are that the cross-conjugated platform allows for the opportunity to optimize the material?s optical and electronic properties for specific applications. Various materials are being prepared and the most promising ones studied further by incorporation into working devices.